Emergy evaluations of and limits to forest production

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Emergy evaluations of and limits to forest production
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xv, 215 leaves : ill. ; 29 cm.
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Doherty, Steven James, 1962-
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Forest ecology -- Mathematical models   ( lcsh )
Biomass energy   ( lcsh )
Forest biomass   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

Notes

Thesis:
Thesis (Ph. D.)--University of Florida, 1995.
Bibliography:
Includes bibliographical references (leaves 205-214).
General Note:
Typescript.
General Note:
Vita.
Statement of Responsibility:
by Steven James Doherty.

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University of Florida
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EMERGY EVALUATIONS OF AND LIMITS TO FOREST PRODUCTION












By

STEVEN JAMES DOHERTY


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY


UNIVERSITY OF FLORIDA


























are the sum of all the


moments of our lives--all that is ours is in them:


we cannot escape or conceal it.


Thomas Wolfe


, Look Homeward Angel


You can feel the anger in water behind a dam.


Barry Lopez, River Notes:


The Dance of Herons












ACKNOWLEDGEMENTS


I am grateful to my committee members, Drs. H.T.


Kiker, B L.


Odum, J.J. Delfino, C.F.


Capehart, and M.T. Brown for their support and encouragement throughout


my graduate studies.


Dr. F.N. Scatena, research hydrologist with the International


Institute of Tropical Forestry was an adjunct faculty member and oversaw my studies


in Puerto Rico.


Professor Per Olof Nilsson, professor with the Swedish University of


Agricultural Sciences in Garpenberg,


as an unofficial member, supervised my studies


in Sweden.


My chairperson, Dr.


Odum, reintroduced the physical and biological world


around me with his energy systems approach,

my role as a scientist and planner. Dr. Brow


widening my world view and redirecting


n has been an advisor, collaborator and


friend, a combination never too common in universities.

Funding in Sweden was provided by the Swedish University of Agricultural


Sciences, Garpenberg, on a grant from


Vattenfall, the Swedish State Power Board,


Project no. 5719-65-312, Energy Evaluation of Forest Systems, P.O. Nilsson,


supervisor

support.


r.


The Swedish Royal Academy of Sciences also provided direct and indirect


Studies in Puerto Rico were funded by a contract between the Institute of


Tropical Forestry, Southern Forest Experiment Station, USDA Forest Service and the


Center for Environmental Policy at the University of Florida, H.T.

Investigator, project 19-93-023. Forest Product Value and Energy.


Odum, Principal

Work in Puerto






Project of the National Science Foundation, Robert Waide and Ariel Lugo, Principal

Investigators.

Many aides and courtesies were provided by staff of the International Institute


of Tropical Forestry:

Parrotta, Elizabeth T


Dr. Ariel Lugo, Samuel Moya, Dr.


revino, and Sylvia DeCastro.


Whendee Silver, Dr. John


Ulf Sundberg, B-O Danielsson, Jan


Erik Mattsson, Jorgen Marks and Kerstin


Efficiency in Garpenberg,


Tordmar of the Department of Operational


Torbjorn Rydberg from the Department of Crop Production


Science in Uppsala, and A-M Jansson, Carl Folke and Monica Hammer with the

Systems Ecology Group at Stockholm University provided valuable input and


participated in discussions and seminars.


Opportunity to continue energy studies was


provided by Dr. R.H. Richardson, Professor with the Department of Zoology, during

my two years with the University of Texas at Austin.

Bo Hektor participated in initial evaluations of electricity options for Thailand.


Naser Altibi and Berdell Knoles


from Gainesville Regional Utilities provided input for


evaluations of electric generating stations in Gainesville, Florida.


I acknowledge the


help of students and staff in the Systems Ecology program, Department of

Environmental Engineering Sciences, and Center for Environmental Policy, especially


Robert Woithe and Joan Breeze.


Finally I would like to acknowledge Sandra, Ulanda,


and Alikai for providing joy and purpose for the completion of this dissertation.













TABLE OF CONTENTS


ABSTRACT ... ........... .


INTRODUCTION . . . 4 . . . ..


Issues and Research Objectives .
Energy Systems Language ....
Concepts and Definitions . .
General Systems Principles .


. . . 2
. . . . 5


. . . . . 6


Indices of Resource Use, Efficiency and Exchange .
Review of Literature on Energy Analyses and Biomass Yields


Limits to Biomass Production


A Short History of Net Energy Analysis


Previous Net Energy Studies of Biomass and Fuels


Forest Systems Evaluated in This Study


Dissertation Plan


* 4 9 9
. .


. 9 . . . 2 6


* 9 4 9
* 9 4I 9 9


Energy Systems Evaluations .
Energy Systems Diagramming
Emergy Evaluation Tables .
Resource Indices and Synthesis .


. . . 3 8
. . . 3 9
. . . 4 1
. . . 4 4


Computer Simulation


RESULTS . . . . . . .. . .. . . .. 46


Emergy Evaluation of Forest Productivity and Extraction


S. . .. . 46


Forests of Southern Sweden
Forests of Southern Illinois
Slash Pine Forests of Florida


- ........... ........... ... 9 9 9 9 9 4 9 4


* 9 4 4 9 9 9 4 4 4 9
* 9 4 9 9 9 4 9 9 9 9 4
* 4 9 4 4 4 4 9 4 9 4 9


METHODS


ACKNOWLEDGEMENTS ......

LIST O F TA BLES .. .. .. .. .. ..................................


LIST O F FIG U RES ...................................... .. .....








Emergy Evaluation of Plantation Productivity ..
Salix Plantations in Sweden . . . .
Melaleuca Plantations in South Florida . .


. . .66


* 9 4 9 9 .* I *
* 4 9 4 9 4 9 4 9 4. 9 9


Siris
Emergy
Carb
Refo
Regi
Emergy
Woo
Pulp
Tour
Emergy
Gain


Plan
Eval
onS
resta
onal
Eval
d Fn


oitat n s i n Puerto Rico


4 - o


uation of
equestrati
tion .
Water Su
uation of
SlCo


Non-market Forest Services
on . . . . .


* 9 I 9 4 4 9
* 4 4 4 9 9
4 9 4 4 4 4 4
* 4 9 4 4 9


Lpply . ...
Forest Economic U


and Paper Products . . .
ism and Recreation . . .
Evaluation of Electricity Generation
esville Regional Utilities . .


Electricity Production in Thailand
Wood-fired Electricity Generation


* 9 4 9 9 4
* 9 4 4 4


* 9 4 4 9
* 9 4 9 I


DISCUSSION


Comparison of Forest Production Systems . ..
Solar Transformities of Agroforest Systems .
Emergy Yield Ratio as a Function of Economic
Optimal Investment for Production and Harvest
Thermodynamic Minimum Transformities for Bi
Emergy Yield and Investments as Functions of (
Comparison of Electric Power Transformation ..
Solar Transformities for Primary Fuels and Eleci
Emergy Yield Ratio as a Function of Economic
Optimal Investments for Primary Fuels and Elec
Thermodynamic Minimum Transformities for Ft
Comparison of Yield and Cycle Time from Forest A
Emergy Yield and Investment as Functions of Fi
Energy Yield and Quality as Functions of Cycle
Relationship of Area and Tme in Biomass Produ


A


9 4 9 4 4 4 9
* 4 4 9 4 9 4 4

Feedback .
of Biomass
omass .
Cycle Time


tricity .
Feedback .
tricity .
els and Ele


* 9 4 9 9 9 4 9 9 9


4 4 4 4 4 4 4 4 4
* 4 9 4 4 4 9 9 9 9I
* 9 4 4 4 9 4 4 9 4

* 4 9 4 4 9 9 *
* 9 9 4 9 9 9 .9
* 4 9 4 4 4 9 4 4 4


Ictri


9 9 *


ltemrnatives . . .
uelwood Transformation
Time and Processing .
action . . .


Computer Models of
Simulation of Em


Systems Principles .
grov Yield and (Cvrcl


y a a -


Mathematical Relationship of
Regional Values . . .
Forest Production and Carbon
Regional Water Supply ....
Summary and Conclusions .


Time


Eme d d investment Rati s *
Emergy Yield and Investment Ratios


Sequestration
. .. .


APPENDIX A.........


* 4 4 4 4


* 9 4 9
* 9 1 9
* 9 4 9


_1_~_~_~











LIST OF TABLES


Definitions of central concepts and units


Solar transformities (sej/J), solar energy per unit mass (sej/g), and solar
emergy-use per gross economic product (sej/$) used in this study to


convert resources


into common units of solar emergy


Summary of data characterizing agroforest ecosystems evaluated in this


study


Emergy evaluation of boreal spruce and pine silvicultural forest production
and timber extraction under 80 year rotation schedules in southern Sweden .

Emergy evaluations of typical loblolly pine and mixed hardwood forest
production and timber extraction under different rotation schedules in


Shawnee National Forest, southern Illinois


Emergy evaluation of slash pine silvicultural production and timber


extraction under


25 year rotation schedules in north Florida


Emergy evaluation of secondary rainforest production and timber


extraction in New Britain, Papua New Guinea


Emergy evaluation of willow plantation production and fuelwood harvest


under 4 year rotation schedules


in southern Sweden


Emergy evaluation of eucalyptus and melaleuca plantation production and


fuelwood harvest under


10. Emergy evaluation of siris
schedules in Puerto Rico


year rotation schedules in south Florida


planation production under 11 year rotation


11. Emergy evaluation of above ground production and biomass storage in
five natural tropical forest ecosystems in Puerto Rico . . .


12. Emergy evaluation of possible reforestation in Puerto Rico using







Emergy evaluation of possible reforestation in Puerto Rico with initial
seeding from exotics facilitating natural succession toward a
secondary forest . . . . . . . . .


Annual volume runoff, energy and solar empower for surface water in
four forested watersheds of Luquillo Experimental Forest, Puerto Rico


15. Emergy evaluation of wood chip production and use as an alternative


biomass fuel for a 10 MW


district heating facility Sweden


Emergy evaluation of wood powder production and use as an alternative


biomass fuel for a 10 MW


Emergy evaluation of recreation


district heating facility in Sweden


n Luquillo Experimental Forest,


Puerto Rico


Emergy evaluation of natural gas-fired electricity production at a
capacity plant in Gainesville, Florida. . . . . .


9.5 MW


Emergy evaluation of natural gas-fired electricity production at a 44 MW


capacity plant in Gainesville, Florida.


Emergy evaluation of natural gas-fired electricity production at an 81 MW


capacity plant in Gainesville, Florida.


Emergy evaluation of coal-fired electricity production at a


18 MW


capacity plant in Gainesville, Florida.


22. Emergy evaluation of natural gas-fired electricity production in Thailand .

23. Emergy evaluation of coal-fired electricity production in Thailand .. .. ...

24. Emergy evaluation of oil-fired electricity production in Thailand ........

25. Emergy evaluation of lignite-fired electricity production in Thailand .


26. Emergy evaluation of eucalyptus plantation production, fuelwood


development and electricity production at a proposed 25 MW


capacity


plant in Thailand .


27. Emergy evaluation of wood-fired electricity production in Jari


Brazi


S .


Summary of measurements calculated from evaluations of







Summary of measurements calculated from evaluations of electricity


generation


30. Comparisons of measurements for three agroforest ecosystems under
different rotation schedules in Sweden . . . . . .


Pathway variables, initial conditions, and calibration of transfer
coefficients for computer simulation model of biomass production and


emergy yield ratio as a function of cycle time


Emdollar (em$) values for forest production and biomass storage in


agroforest


ecosy


stems evaluated


n this study


Emdollar (em$) values for surface water runoff from four forested


watersheds in the


Luquillo Experimental Forest, Puerto Rico












LIST OF FIGURES


Systems diagram relating principles of self-organization, maximum power,
thermodynamic efficiency and net yield for two paradigms of resource-use:
(a) natural, unmanaged ecoystems; (b) managed agroforestry systems .


Symbols and definitions of energy language diagramming used to
represent system s . . . . . . .....


Energy transformations and hierarchical ordering of ecosystems illustrating
the concept of solar emergy: (a) spatial pattern; (b) system network;
(c) network aggregation by hierarchical levels; (d) sequential energy flows;
and (e) solar transformities . . . . . . . . .


Calculation of measurements made for resource-conversion systems:
(a) solar transformity; (b) emergy ratios of yield and investments;
(c) emergy exchange ratio of an economic transaction . . . ..

Overview diagram for comparing benefits of a proposed resource-use
system with the current one it would replace or with other sectors
typical of a region . . . . . . ...........


Allocation of gross production in different agro-forest systems


. 4 *.


The time-information-energy triangle identifying an output as a trade
off between three parameters . . . . . . .


Systems diagram of boreal spruce/pine silvicultural forest production and
timber extraction under 80 year rotation schedules in southern Sweden .

Systems diagram of unmanaged forest production in northern
coniferous ecosystems of southern Sweden: (a) self-thinned, natural
mixed coniferous forest regeneration,100 years old; (b) old growth
spruce forest, 200 years old . . . . . . . .


Systems diagrams of typical loblolly pine and mixed hardwood silvicultural
forest production and timber extraction under different rotation schedules
* .^L --a*k a T.. ,. a a -. I ". 4 nR.^.a^I4L s.-ant.. ^.4A.,, Tlan i .n, aw&,







Systems diagram of secondary tropical rainforest production, above
ground biomass storage and timber extraction in New Britain,


Papua New Guinea


Systems diagram of willow plantation production and fuelwood harvest
under 4 year rotation schedules in southern Sweden . . . .


Systems diagram of eucalyptus and melaleuca plantation production and


fuelwood harvest under


year rotation schedules in south Florida


15. Systems


diagram of siris plantation production and possible


fuelwood


harvest under 11 year rotation schedules in Puerto Rico


16. Systems diagram of above ground production and biomass storage in four
natural tropical forest ecosystems in the Luquillo Experimental Forest,


Puerto Rico


Systems diagrams of possible reforestation of degraded agricultural lands


to secondary forests in Puerto Rico:


(a) assisted reforestation using


plantations as foster ecosystems; (b) natural reforestation through
successional organization of native and introduced species . .

18. Systems diagrams of water cycles in four forested watersheds of the


Luquillo Experimental Forest, Puerto Rico:


(a) overview diagram of


energy flows and transformations of water; (b) solar empower of incident


rainfall, forest evapotranspiration and surface water runoff


Systems diagram of wood chip production and use as an alternative biomass
fuel for district heating in Sweden . . . . . . . .


Systems diagram of wood powder production and use as an alternative
biomass fuel for district heating in Sweden . . . . .


Systems diagram of chemical production of one ton of wood pulp ......

Systems diagram of mechanical production of one ton of wood pulp .


Systems diagram of production of one ton of paper


Systems diagram of annual environmental production and economic
services supporting multiple-uses in Luquillo Experimental Forest,


Puerto Rico






26. Aggregate systems diagrams for electricity production (1 MWh) using


four non-renewable fuel sources in


Thailand:


(a) natural gas; (b) coal;


(c) oil; (d) lignite


Systems diagrams of theoretical wood-fired electricity production in
Sweden: (a) wood chips; (b) wood powder . . ... .


Systems diagram


MW


of wood-fired electricity production:


(a) proposed


capacity plant in Thailand; (b) 53 MW plant in Jari,


Brazil


Environmental and economic components of solar transformities


evaluated agro-forest ecosystems:


(a) above ground production; and


(b) harvested biomass, rank ordered by cycle time


Emergy yield ratio as a function of economic feedback for evaluated


agro-forest ecosystems:
(b) harvested biomass


(a) silvicultural forest production; and


Solar transformity as a function of emergy investment ratio for evaluated


agro-forest ecosystems:
(b) harvested biomass


(a) above ground production


Emergy yield ratio as a function of cycle time for evaluated agro-


forest ecosystems:


(a) above ground production; and


(b) harvested biomass


Emergy investment ratio as a function of cycle time for evaluated


agro-forest ecosystems:
(b) harvested biomass


(a) above ground production; and


Environmental and economic components of solar transformities for


evaluated systems of electricity generation:


(a) primary fuel source;


and (b) electricity


Emergy yield ratio as a function of economic feedback for evaluated


systems of electricity generation:
(b) electricity . . . .


(a) primary fuel source; and


Solar transformity as a function of emergy investment ratio for evaluated


systems of electricity generation.


: (a) primary fuel source; and


(b) electricity


Effect of of increasing electric generating capacity on


(a) solar transformity


. . 1






Systems diagrams of biomass production, storage, fuelwood development
and heat generation from agroforest systems under three different


management schedules in southern Sweden:


(a) natural, old growth spruce;


(b) managed spruce/pine; (c) plantation willow


39. Comparisons of measurements for three agroforest systems under
different rotation schedules for the development of fuelwood for possible


heating and electricity generation:


(a) solar transformity; (b) emergy


yield ratio; and (c) energy investment ratio


S . 1


40. Comparisons of measurements for three agroforest systems under
different rotation schedules for the development of fuelwood for


possible heating and electricity generation:


(a) emergy per ton fuelwood


(b) annual available energy yield; (c) equivalent land area requirements

41. Systems diagram and equations for simulation model determining
biomass production and emergy yield ratio as a function of cycle time


for agro-forest systems


Computer simulation of forest development as a function of cycle time:
(a) gross and net production; and (b) above ground biomass
accum ulation . . . . . . . . . .


43. Computer simulation of emergy yield ratio as a function of cycle


(a) net above ground production


time:


and (b) harvested biomass


44. Emergy yield ratio as a function of emergy
evaluated agro-forest ecosystems: (a) abov
(b) harvested biomass . . . .


investment ratio for


e ground production; and


Systems diagram and equations for minimodel of general production relating


indices of energy yield and investment


46. Computer derivation of the relationship between (a) emergy yield and investment
ratios; and (b) solar transformity and investment ratio for minimodel of general


production


Solar transformity as a function of biomass production and storage for
evaluated agro-forest ecosystems: (a) empower of above ground
production; and (b) emergy stored in above ground biomass . .


Solar transformity of surface water runoff as a function of empower
for elevational forest watersheds of Luquillo Experimental Forest,








Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy


ENERGY EVALUATIONS OF


AND LIMITS TO FOREST PRODUCTION


By

Steven James Doherty


December 1995


Chairman:


Howard T.


Odum


Major Department:


Environmental Engineering Sciences


Temperate and tropical forest systems in Sweden, Puerto Rico and other areas,


ranging in age from


and 300 years, were evaluated with energy systems methods to


investigate net yields, economic requirements, and limits of biomass production from


solar energy.


Inputs and products were measured on a common basis in units of solar


emergy (solar emjoules--the solar energy required directly and indirectly to produce a


product or service).


Forest growth and harvested biomass,


were compared along with


water supply, reforestation, pulp, paper, and recreational use.

Net emergy yields increased with length of growth cycle, ranging from 1.5 for

plantations to more than 12 for unmanaged forests with economic investments as much


as ten times greater for managed systems.


Preparing biomass for conversion to


electricity required greater emergy inputs than was required for processing fossil fuels.







Emergy yield ratios for natural gas and coal-fired were between 3 and 6 and less than


for wood-fired electricity.


Solar transformity, a measure of emergy used per unit energy produced, for

above ground biomass production was less than 10,000 sej/J (i.e., solar emjoules per


joule) and between


100,000-200,000 sej/J for electricity.


The lowest value in each


category may approach the most efficient conversions thermodynamically possible


consistent with operation at maximum production.


In Puerto Rico, reforestation using


plantations (34 years) and exotic invasions (50 years) minimized economic

requirements and increased net yields.

Emergy yield is inherently dependent upon growth time for biomass systems.

Sustainable long-run forests which rely on flow limited, renewable emergy often

exhibited greater net production than managed short rotation forests, yet net biomass

production is often smaller because more is reinvested to design and maintain diverse


structure and autogenic pathways.


Although technology may increase energy


conversion efficiencies, additional investments reduce net yields below currently

available primary sources.

Because of energy conversion and temporal limits to biomass production,

agroforest systems cannot currently compete with fossil-carbon fuels, until

nonrenewable sources become limiting, lowering net yields for all existing fuels.

Human carrying capacity would be less than half its current size and a general slowing

of global economies would be necessary if only renewable fuel sources were available.











INTRODUCTION



To replace the nonrenewable sources of fuel and electricity as their availability


decline


research continues for renewable alternatives.


One of the main possibilities


is solar-based, organic biomass from agriculture and forestry.


practical questions include:


Major theoretical and


1) what are the best possible net yields from biomass;


2) are there biophysical limits to biomass production; and 3) how is time related to net


resource yield?


In this


dissertation, energy systems methods are used to evaluate


production and multiple-use of a wide range of agroforest systems under different


management schedules


from temperate and tropical latitudes.


Net emergy measures


are used to compare biomass fuels with current alternatives in the generation of heat


and electric'

products.


city


. Energy-based measures are compared with market values for forest


An effort is made to determine the thermodynamic maximum production of


biomass.


By considering full cycles of growth, harvest and regrowth,


related to the rotation period.


net yields are


Computer simulation is used to relate inputs, cyc


time,


and yield.


The discussion considers the implications of biomass limits for world


reforestation, human carrying


capacity


and global environmental-energy policy


Forest systems worldwide are increasingly being reorganized by human


interactions.


Old growth forests are cleared and replaced with managed ones;


silvicultural practices are reducing the turnover time of forest biomass; forests are





2

exploitation, now global in scale, new and old systems of utilization are needed that


are both productive and sustainable.


Further, as the availability of fossil fuels


decreases, the controversy increases over what is the maximum sustainable conversion


of biomass and fuels from renewable solar energy.


Recognition and quantification of


the full range of values forests provide, including those outside the market economy,


are needed in order to determine best uses of forest ecosystems worldwide.


Issues


such as these require new and comprehensive assessments if scientists, land managers

and ultimately policy makers are to make sound decisions regarding our forest

resources and their roles in future questions of energy supply and global processes.



Issues and Research Objectives



Sustainable, long-run natural forest systems which rely on renewable

environmental energies, often exhibit greater gross production than managed


plantations, yet generally have smaller net yields.


This is because more of their


production is re-invested to design and maintain diverse structure and cooperative


pathways (Figure la).


In agriculture and forest plantations, feedbacks in the form of


fossil fuels, irrigation, pest management, planting and thinning direct more of the gross

production into extractable biomass producing greater yields per unit time (Figure lb).

Agro-ecosystems which are reliant on purchased subsidies often increase yields, but


because of large investment requirements, may deliver little "net"


contribution,


possibly with required inputs being diverted from more competitive or efficient
















Natural
capital


Recycle,
diversity


Ecosystem
production


Resources


Ecosystem
services


i -- -I


;- --


Silviculture,
management


Environmental
sources


Agro-forestry
production


Crop yield


c- -^


Main
economy


-a---


Fimure 1


Systems diagram relating orincioles of self-organization, maximum power,


Harvest





4

Silviculturally managed forests shorten the rotation time between harvestable


yields of forest biomass.


from


Managed forest stands are clear-cut on rotations ranging


years for pine in the southeastern U.S. to 80 years or more for northern mixed


coniferous forests in Sweden.


Plantations harvest fuelwood as often as every 4 years.


Cleared land is often scarified; seedlings are planted; the stands are thinned; access


roads and drainage ditches are built and maintained.


Thinning operations act to reduce


competition for resources, increasing available sunlight, precipitation and soil nutrients


for the remaining trees, generally increasing productivity.


Fuelwood and pulpwood


yields may be delivered from thinning operations, and the remaining trees have greater

stemwood volume and wood density making the trees of the final harvest more


commercially valuable.


All of these attributes require economic inputs, reducing the


net yields of delivered products.

All resources and ecosystem processes require a minimum amount of energy


for production and maintenance.


Ecosystems, through processes of self-design, may


maximize gross production based on flow limited, renewable resources.


Natural


systems may be more efficient systems than managed agro-ecosystems, although their


turnover times, and thus their rates of delivery are slower.


This postulate and limits to


the conversion of biomass from solar energy suggest a thermodynamic minimum

transformation of total resources supporting production.

Thus, there is a trade off between management resources and rate of delivery of


forest products.


The tradeoff lies in the increased investments required for shortened


rotations and increased fields


Traditional economic accounts of forestry systems





5

often support increased management initiatives; biophysical accounts of forest

operations often argue for less investment, slower returns but greater net yields.

Often, only forest products with current market value are recognized, and non-

market services such as carbon storage, watershed protection and wildlife habitat are


not considered in conventional benefit/cost studies.


If these other "co-product" or non-


target services are considered, the net benefits derived from forests may be


the price of forest products.


arger than


Growing forests for wood ignores the other contributions


that a well-organized ecosystem proffers.


Finally, renewab


fuels


are increasingly being reconsidered as alternatives to


fossi


and nuclear fuels as supplies of these fuels diminish and concern for the


environment increases.


alternatives


Biomass fuels


are being promoted as competitive and viable


since carbon emissions are abetted by forest production.


However, these


assessments do not consider indirect carbon emissions from activities necessary to


develop the resource nor do they consider the important role


of time in developing


high net yields.


Primary fuel


with high net yields may emit lower carbon dioxide


levels per unit output.


These issues suggest that forests offer multiple services, and


that single-use management may not properly


assess


whole


stem benefits.


Ener.y


stems Language


Ecosystem concepts, system configurations, and computer models


renrecarnted in this dipsertatinn with enermv circuit


1


an uage (Odum 1971


- 1983.







represent system components including storage, flows and sources.


The symbols have


specific mathematical and energetic relationships when drawn in ordered fashion into


energy systems diagrams.


These symbols are defined in Figure


diagramming


conventions are given in the Methods section of this study.


graphical inventories and impact statements.


Systems diagrams are like


Energy circuit language helps recognize


and represent networks, organization and order within systems.



Concepts and Definitions


General Systems Principles


Systems theory arose from the observation that models describing and


predicting diverse "systems"


often have certain common or similar principles which


influence the design and outcome of the models.


In Figure 3, principles of self-


organization, hierarchical ordering and energy transformation are illustrated as


thermodynamic principles common to all systems.


Table


lists definitions of terms


and central concepts used in this study.


Below are further discussions of general


principles.

Using concepts from ecology, an energy hierarchy is identified in Figure 3a

(Odum 1987) in which many small components with short life spans (rapid turnover)

and small territories are required to support few large individuals with greater life


longevity and larger territories.


Common to all levels or systems shown here is an


...... ..- .- .. 1 ,_ 1._ ..----.--- --- J.L ..----- ^.... -..... ... .. .A.. -- .. a.&l,- -. t "









Energy circuit.


A pathway whose flow


is proportional to the


quantity in the storage or source upstream.
Source. Outside source of energy delivering forces according to a
program controlled from outside; a forcing function.

Tank. A compartment of energy storage within the system storing a
quantity as the balance of inflows and outflows; a state variable.

Heat sink. Dispersion of potential energy into heat that accompanies
all real transformation processes and storage; loss of potential
energy from further use by the system.

Interaction. Interactive intersection of two pathways coupled to
produce an outflow in proportion to a function of both; control
action of one flow on another; limiting factor action; work gate.

Consumer. Unit that transforms energy quality, stores it, and feeds it
back autocatalytically to improve inflow.



Switching action. A symbol that indicates one or more switching
actions.


Producer. Unit that collects and transforms low-quality energy
under control interactions of high-quality flows.

Self-limiting energy receiver. A unit that has a self-limiting output
when input drives are high because there is a limiting constant
quality of material reacting on a circular pathway within.


Box. Miscellaneous symbol to use for whatever unit or function is
labeled.

Constant-gain amplifier. A unit that delivers an output in
proportion to the input I but changed by a constant factor as long as
the energy source S is sufficient.



Transaction. A unit that indicates a sale of goods or services (solid
line) in exchange for payment of money (dashed line). Price is
shown as an external source.















Solor
Crmergy Flow:




Solor










Aggreqated:







Solor EMERGY I

~** -*
a


a
i
9
I-
Se


SE9 Solor nljou/lu/TIrme
*e -
I, "" '" I ""-" "S

I a I
I I I
o
I a I
I i i
t 6E7 s I i i


I
I
I

* 10,000


100,000


0 I 2 3 4


Tronsformoctn Steps


Figure 3.


Energy transformations and hierarchical ordering of ecosystems illustrating


*1/ a rnran n enjorrn (o'Ic ol nt~ (\ etSr^-arn na*,tmnrb


* @0.@00* *
**0 **
e**. **
e O O0
.* ***.*
*** *,

** **
OO0
O00.0O


p ..
* *
^_-


*


+ha trnnrtf n, ctnlir lnrirrr r-







Table 1


Definitions of central concepts and units used throughout this study.


1st law of thermodynamics: Also termed the law of conservation of energy, this principle
states that energy is neither created nor destroyed, thus energy entering a system must be
accounted for as either stored or outflowing.


2nd law of thermodynamics:


This principle states that all energy transformation processes


degrade energy


-- that available energy loses its ability to do useful work.


Energy lost


to a system is identified as degraded heat with an overall entropy increase.


Energy:


A property of all things which can be turned into heat, energy is measured in


heat units [British thermal units (BTU), kilocalories (kcal), or joules (J)].


Available energy:


process.


Used energy:


Potential energy capable of doing work and being degraded in the


This is also termed exergy.


Energy whose availability has been used up in a transformation process


according to the second law and no longer able to accomplish useful work.


Renewable energy:


Energy flows, such as sunlight, rainfall and wind, generally recurring


and which ultimately drive the bio-chemical processes of the earth and contribute to


geologic processes.


Renewable sources are ultimately limited by their flow rates


systems cannot draw from these sources any faster than they are delivered.


Nonrenewable energv:


replacement.


Energy and material storage that are used up at rates faster than


Examples include fossil fuels, mineral ores and soils.


Gross photosvnthetic production:


Energy transformed through photosynthesis, often


measured as total carbon sequestered in plant biomass or as oxygen produced.


Net production:


Available energy flow or storage remaining after one or more flows


subtracted.


Efficiency:


The ratio of useful energy output to total energy input to a production system.


Net storage turnover time:


The time required for the replacement of a quantity, obtained


by dividing the quantity by the difference between the inflow and outflow rates.


Cycle time:


The period of time lapsed between the beginning and end of an oscillation.


It is used here to quantify forest rotations of growth, harvest and regrowth.


Market value:


The price, assigned a commodity or activity addressing the human services


rendered in recovery, production and delivery (i.e., market supply) and subject to demands


of the consumer.


It is an assessment of opportunities forgone from using resources in the


present and thus lost to the future.








Table 1--continued.


Emergy:


Available energy of one kind previously used up, directly and indirectly, to


make a product or service.


Solar emergv:


The solar energy used up directly and indirectly through transformations


to make a product or service.


Solar emioule:


Empower:


The unit of measure of solar emergy, abbreviated sej.


The flow of emergy per unit time.


Solar transformitv: The ratio of solar emergy used up in a transformation process divided


by the available energy yielded, measured


sej/J (Figure 4a).


Energy transformation


hierarchy:


Systems self-organize such that energy


flows


hierarchical with many joules of kind of energy required in trasnformations to produce


the next kind.


Transformities measure position within energy hierarchies.


Maximum empower principle:


effective advantage of available emerge.


this by:


Systems that tend to prevail are those that take the most


Systems, economic or ecological, accomplish


reinforcing productive processes, drawing more resources, and overcoming more


limitations through effective system self-organization.


Feedbacks:


Consumer pathways


that reinforce


productive flows


and help


develop


optimum efficiencies.

Emdollar (em$): The portion of gross economic product attributed to an emergy-use.
The em$ is obtained by dividing an emergy flow or storage by the sej/money index for
a region/nation.


Emerev/money ratio:


A measure of emergy-use supporting economic activity, generally


calculated by dividing the gross economic product of a region into the area's annual
emergy use, measured in units of sej/S.


Net emerev yield:


Emergy derived from a productive process minus emergy fedback


from economic sources (Figure 4b).

Emergy yield ratio: (YR) The emergy output from a productive process divided by the


emergy fed back


from economic sources (Figure 4b).


Emerev


investment


ratio:


energy


economic


sources


divided


environmental emergy sources (Figure 4b)


Emerev exchange ratio:


The ratio of emerev received to emerev delivered in a trade or







losses occur according to the second law (Figure 3b).


Therefore very little available


energy remains after several transformations of the original energy.


Because each of


these steps is required, the total influx of independent energies (in this example there


is only one--sunlight) is required to support each transformation step (Figure 3c).


takes increasingly more solar energy to support a given unit of energy going from left

to right along the energy hierarchy (Figure 3d).

The solar transformity estimates the amount of available energy of one type

(i.e., solar) required through transformations to produce the available energy of another


type (Odum 1983,


1988; Scienceman


1987).


It is a measure of position and influence


within a system.


The work that potential energy can do is then dependent upon its


position in the hierarchical web of energy transformations.


A list of the solar


transformities and indices of solar energy per unit mass and solar emergy per gross

economic product, used to convert environmental flows, purchased fuels, commodities,


and human services to solar emergy in this study, is given in


Table


The method of


calculating solar transformities in this study is given in Figure 4a.


Since human


services are calculated separately as inputs to production, to reduce the error of double

counting, transformities for primary fuels and electricity used as system inputs in this


study (items 9-13,


Table 2) were considered lower conversion limits without economic


services.

Solar emerge is defined as the product of the available energy and its solar


transformity (Odum 1983, 1988).

commensurate to its requirements.


It may be a measure of real contributions

Solar emergy is the common unit of measure used






12

Table 2. Solar transformities (sej/J), emergy per unit mass (sej/g) and emergy/money
ratios (sej/$) used in this study to convert resource measures into units of


solar emergy.


Calculations for additional conversion values are given as


footnotes accompanying emergy evaluation tables.


Solar transformities


derived from evaluations in this study are denoted ST,.


Solar emergy
per unit


Note


Solar energy
Wind, kinetic


energy


Rain, gravitational potential energy
Rain, chemical potential energy
Physical stream energy
Chemical stream energy
Soil organic matter


Lignite


Natural gas
Crude oil


Refined petroleum
Electricity
Irrigation water

Concrete
Machinery, steel prod.


Fertilizer, general


Potassium
Nitrogen
Phosphorus


10,500
18,200
27,800
48,450
74,000
37,000
29,000
34,800
40,200
47,900
1.25E+5
2.55E+5

1.5E+06
6.7E+09
4.8E+09
2.0E+09
4.2E+09
2.0E+10


Human services:


Sweden


Puerto Rico


Thailand


Brazil


Papua New Guinea


1.53E+12
1.60E+12
1.64E+12
3.69E+12
6.09E+12
4.80E+13


Notes.


Solar energy by definition


sej/J (Odum 1988,


1995a)


Wind n ped at cnirfann nf thp anrtlh pctimrntd nc 1 (/ nnf tntal f1hiv nf wind pnirarVl


1 O1+4-17 kiW







Table 2--continued.


Physical energy of rainfall on elevated land: world's rain over land


elevation of land


= 875 m;


(1.05E+5 km3) (IE+12 kg/km3) (9.8 m/si


105,000 km3/yr; average
ec2) (875 m) = 9.0E+20 J/yr;


= (9.44E+24 sej/yr, global emergy flow)


(9.0E+20 J/yr)


= 10488 sej/J


Chemical potential energy of rain: world's rain over land


= (1.05E+14 m3/yr) (1E+15 g/km3) (4.95


J/g Gibbs free energy)
J/yr) = 18199 sej/J


Physical energy in stream flow:
m, average world elevation) =


.187E+20 J/yr; ST


= (9.44E+24 sej/yr, global energy flow) / (5.187E+20


(3.96E+4 kmn/yr global runoff) (IE+1


3.395E+20 J/yr; ST


kg/km3) (9.8 m/sec') (875


= (9.44E+24 sej/yr, global emergy flow) /


= 27806 sej/J


Chemical potential energy in streams: (3.96E+4 km3/y
Gibbs free energy at 150 ppm typical dissolved solids)
global emergy flow) / (1.948E+20 J/yr) = 48460 sej/J


r, global runoff) (IE+15 g/km3) (4.92 J/g,
= 1.948E+20 J/yr; ST = (9.44E+24 sej/yr,


. Odum et al. (1983); updated in Odum (1995a)


Odum et al. (1987)


Sedimentary coal, in situ; ST


Natural gas


= 29,000 sej/J;


39800 sej/J for processed coal (Odum 1995a)


= 20% more efficient in boilers than coal (Cook 1976);


est. ST (without services)


= (1.2) (29000 sej/J; item 7)


Crude oil:


= 34800 sej/J; 48000 sej/J for processed nat. gas (Odum 1995a)


Refinement and transport of refined fuels uses 19% crude petroleum (Cook 1976)


est. ST (without


services


= (47850 sej/J; item


11 below) / (1.19)


= 40200 sej/J; 53,000 sej/J for


processed, delivered crude oil (Odum 1995a)


Refined fuel oils:


1.65 coal-J/oil-J (Slesser 1978);


est. ST (without services)


= (1.65) (29000


sej/J)


= 47850


sej/J; 66000 sej/J for processed, delivered oil (Odum 1995a)


Electricity:


= (2.6) (47850 sej/J)


fuel-J/electricity-J (Swedish Power Assoc.


= 124,500 sej/J; Odum (1995a) uses


1981);
2.0E+5


est. ST (without


services)


Odum et al. (1987)
Brown and McClanahan (1992)
Odum and Odum (1983)
Fertilizer estimated from weighted average of items 18, 19, 20 below, assuming typical forestry
N:P:K ratio of 30:3:10
Odum and Odum (1983); updated in Odum (1995a)
Odum and Odum (1983); updated in Odum (1995a)
Odumn and Odum (1983); updated in Odum (1995a)
Doherty et al. (1993)
Odum (1995a) for 1990 (U.S. sej/$ ratios for other years are identified as footnotes to tables)
Doherty et al. (1994)
Brown and McClanahan (1992)
Comar (1993)
Dohertv and Brown (1992)


(3.395E+20 J/yr)










Source
F


Source
F2


Measured in units of
solar emergy (sej)


output (y)
Measured as
available energy (J)


Degraded energy


Solar transformity for output


emergy of inputs (sej)
energy of output (J)


(l1+ FF)


C
- - -


Environ-
mental
sources


4- --- - -


(sej/unit/time)


Emergy yield ratio


Emergy investment ratio


Y. / F.
S *II


Fi /


Payment


Resource
conversion


Regional
economy


- 1 1 r


~I) 1




15

As available energy dissipates and is used up through transformations (Figure 3), the

solar emergy remains unchanged, because at each step all previous energy


transformations are required, going back to the original source at the


eft, solar power.


A general hypothesis emerges from an understanding of thermodynamic laws,


energy transformations and hierarchical ordering:


systems organize over time to


develop structures and cooperative pathways that stimulate productive processes which


capture and use effectively the available energy.


Components and processes at the top


of the hierarchy,


requiring a lot of source energy,


contribute to lower level processes


through feed back mechanisms which amplify lower


evel actions.


These include


autocatalytic processes to insure and increase the


influx of energy from available


sources and optimize efficiency that is compatible with maximum use.


This principle of maximum empower (Odum 1988,


995a) states that the


system design (i


.e., production system or development alternative) that will prevail in


competition with others is the one that develops designs with reinforcement actions,


that yield the most useful work using inflowing emergy sources.


Energy dissipation


without "useful" contributions does not reinforce and thus cannot compete with

systems that use inflowing emergy in self-reinforcing ways.

The thermodynamic minimum transformitv is defined here as the lowest


possible amount of emergy necessary to produce a quantity or sustain a process.


argued here that reforestation and forest rotation systems that require more than the

thermodynamic minimum are inferior as measured by the deviation from the best value

of net emergy per cycle time.







Another theorem investigated here is that the area receiving the more solar


emergy due to the market transaction has its economy stimulated more.


Previous


studies have indicated that raw products such as minerals, rural products from

agriculture, fisheries, and forestry generally tend to have high net emergy benefits to


purchaser when sold at market price (Odum 1984, Odum and Arding


1991, Doherty


and Brown


1992).


This is a result of money being paid for human services and not


for the extensive work of nature that went into these products.



Indices of Resource Use, Efficiencies, and Exchange


By keeping track of the origins of resources in production systems, whether

from they are economic sources or from environmental sources, renewable or non-

renewable, indices of yield, investment and exchange can be calculated to synthesize


analyses and make comparisons between systems.


In the indices that follow, resources


required to produce a yield (Y,) are identified as either environmental in origin (I,) or

economic (F,).

The emerge yield ratio is the emergy of an output (Y,) divided by the emergy

of those inputs to the process that are purchased from the economy (F,) (Figure 4b).

This ratio indicates whether the process can compete in supplying a primary energy


source for an economy.


Typical, competitive fuel sources on world markets have been


between 3 and 15, but are usually about 4 or 6, though these favorable ratios are

declining as fossil reserves decline and extraction and processing costs increase (Odum


1995a).


Since fuels can be substituted, processes with yield ratios less than available






The emerge investment ratio is the ratio of energy derived from the economy


(F,) to the emergy delivered "free" from environmental sources (I,) (Figure 4b).


ratio indicates if the process is competitive as a utilize of the economy's


in comparison with alternatives.


This


investments


To be competitive, the process should have a similar


ratio to its competitors.


If it receives


from the economy, the ratio is lower and its


prices are lower so that it will tend to compete in the market place.


Prices are lower


when a production process is receiving a higher percentage of its useful work from


environmental inputs than its competitors.


The investment ratio can also be considered


an environmental loading ratio, a measure of potential impact or "loading" a particular

development activity can have on its environment.

The emergy exchange ratio is the ratio of solar emergy received to solar


emergy delivered in a sales transaction.


It is calculated as the solar emergy of the


product sold divided by the solar emergy that could be purchased with the earned


revenue (Figure 4c).


Dollar revenues are converted to solar emergy using the


emergy/money ratio (defined next) for the purchasing region.

An index of annual emergy-use and gross economic product of a region

(emergy-use/GP) is considered an estimate of the solar emergy supporting each unit of


currency circulating in the economy for a particular year.


In general,


rural countries


tend to have higher emergy/money ratios because more of their economy involves


direct environmental resource inputs that are not paid for (Odum and Odum


1983,


Odum and Arding 1991


Doherty and Brown


1992).


The term emdollar (abbreviated em$) refers to the total amount of dollar flow






from a production sector.


It is calculated by dividing the solar emergy of a product or


process by the emergy/dollar ratio for the economy to which it contributes.


This is a


method of putting a monetary value on services and storage not traditionally

accounted for in economics such as transpired rainfall, photosynthetic production,


forest biomass, and information.


This is not a market value, but instead a value for


public policy inferences and directives.

Resource development projects can be evaluated and compared among

alternatives and net contributions of sectors typical for a region so that decisions can


be made in advance of implementation (Figure 5).


In this study, proposed forest-uses


are compared with alternatives and with current sectors using the resource indices


defined above.


Best uses are considered those that maximize emergy flow for the


region and draw the highest net energy.

Usually questions of development policy and resource-use involve


environmental impacts that must be weighed against economic gains.


Often impacts


and benefits are quantified in different units resulting in a paralysis of the decision-

making process because there is not a common means of evaluating the tradeoffs


between environment and development.


The systems analysis procedure is designed to


evaluate the flows of energy, information, materials and money in common units that

enable one to compare environmental and economic aspects of systems.

Measurements in this study were organized to evaluate thermodynamic properties

common to all systems; each component of a self-organized system is coupled to

lower and higher levels and all components contribute to system performance





19










F1


SProposed e
project .......----- -




F
SP___ _, _(Pce)
I2
12 Current 2
resource-use 4---------- --
Main
economy
Environmental

SO/O - - -^- -(Pi e
FF
3 \ -

33
Alternatives -. --- ---- -





FM


Typical '4 ,
sectors --- -- -- -- -







ilre S fvser darm fnr rnmnnno reolnnl heneft f- nrnnn-e renre-le


Fionrp 5 f^\/rv/iw c>i liaorfl~ for rnmnarnnn racional hanpfitQ off nrnannaft rftsource-ulse







Review of Literature on Energy


Analyses and Biomass Yields


Limits to Biomass Production


Biomass production for fuel-use is limited by a number of factors including

conversion efficiencies, amenable and available land area, energy content and

concentration of wood, delivery rates, and reductions in net yields due to management


Investments.


Net photosynthetic conversion efficiencies range from less than 1% for


trees and most agricultural crops (Slesser 1984) to


3.5%


for some C3 plants and up to


5% for C4 plants (Keeton and Gould 1993).

thus are considered upper conversion limits.


These values are daily maximums and

A general, mean photosynthetic


efficiency for woody biomass systems would likely be below 1%.


The sun's energy is


flow limited, delivering on average 58E+12 J/ha/yr in the U.S. after albedo and

atmospheric absorption are subtracted (Boyles 1984), limiting maximum possible

biomass production.

In a discussion of limits to biomass energy supply, Smil (1983) argues that


even with very optimistic assessments of biomass conversion of solar radiation,


all productive lands (including agriculture) in the United States cultivated for fuelwood

production, biomass energy could still only account for 5-10% of the country's annual


energy consumption.


Pimentel et al. (1978) present a similar example:


the maximum


amount of sunlight fixed by all biomass in the U


was only about 70% of the total


annual use of fossil fuels in 1978; and biomass from agriculture and forestry together


was less than 30%.


Renewable energy sources are flow-limited (Odum


1983) meaning





21

These figures are illustrative of the difficulties that could arise if the global economy

tried to switch from using non-renewable storage of fossil carbon fuels to renewable

sources without down scaling.

Older ecosystems channel more of their productivity into maintenance and


diversity, producing very small net annual yields (Figure 6).


stating concepts outlined in Figure 1.

develop toward maximum biomass pro


is another way of


Margalef (1963) proposed that ecosystems

duction. In late seral stages of succession, the


quotient of production/biomass drops suggesting that more biomass can be maintained


for less net production -- a measure of system efficiency.


Odum (1970) proposed that


ecosystems maximize power not biomass, and only build the amount of biomass that is


necessary for maximum


gross


production.


By considering gross production


as a function of biomass instead of the other


way around as Margalef (1963) interprets the relationship, a diminishing return on

biomass affecting gross production is realized and maintaining biomass levels beyond


an optimum level for maximum power is wasteful.


There is a point when energy


required for maintenance is equal to gross ecosystem production (when net production


approaches zero).


When the metabolic costs of maintaining structure exceed gross


production, mature systems may turnover in order to produce configurations in space


and time that maximize empower.


This suggests there are optimal rotation periods


based on production and stored biomass capacity of ecosystems.

The concept that power is maximized in systems was put forth by Boltzmann


(19051 and Lotka (1922ttbased on earlier ideas from the previous century.


Odum and
















Old growth forests,
rainforests


Medium aged,
managed forests


Short-rotation
tree plantations


Annual


leguminous crops


I
50%


ED


Figure 6.


I
100 %


Autotrophic respiration

Heterotrophic respiration


I Net community production





Allocation of gross production in different agro-forest ecosystems.
Although gross photosynthesis in natural forests is large, more is used up in
community respiration maintaining diverse structure and cooperative
nathwave Net nrndiietivitv is nAften a small nercentaoe nfthe arnss rate







maximizes power in an energy storing process.


regulator."


This was termed "time's speed


This important relationship identified maximum power (i.e., maximum


energy flow per unit time) as a function of the loading ratio and showed how time of


storage has thermodynamic limits.


empower (Odum


These early theories are now restated as maximum


1983, 1988) defined in the concepts section of this dissertation.


Spreng (1978, 1988) also introduced the concept of time into energy analysis.


He proposed a time-energy-information triad (Figure


affected by these three parameters. Usin

biomass increases with available energy,


growth.


7) in which the product is


lg forests as an example, net storage of

with useful information and with time of


Any point inside the triangle is a combination of all three parameters, and


each can be generally substituted for another with all three inputs necessary to produce


an output.


Perhaps if each parameter was evaluated in emergy units, the sum of all


three inputs (100%) along triangular coordinates would equal that of the process


output.


The author restates the principle that energy conservation measures are time


dependent; that efficiency is ultimately related to power output.

Net emergy delivered from resources is a function of resource concentration.

Sources of dispersed energy requiring processing to be useful, have low net emergy


yields.

energy.


Processes of concentration and transformation require inputs of time and

Renewable, solar-based energy sources are both flow-limited, requiring time


to deliver, and dispersed, requiring energy for concentration.


temporal dimension to net energy (termed


Sedlik (1978) proposed a


'gain function') suggesting that technological


^j..-,,^^.n^-r. n ;.,...-n,,a na+ .,1A0o .1,h; lnl rrcanirra hnnlatoinn artc tn Inwer net vields






































Information = 0


Maximum
available time


Energy= 0


Figure 7


The time-information-energy triangle identifying an output (Y) as a trade
off between three parameters (from Spreng 1988). Energy efficiency is
identified as a function of power output, which requires information about
the system.







A Short History of Energy Analysis


Since the oil crises of the 1970s, the concept of "net energy analysis" has been


used to


assess


the energy requirements of energy systems.


Odum (1967


1971)


introduced "net energy" as a new and important concept with his book Environment,


During this period, new studies and workshops were set up such


as the international program coordinated by


Malcolm Slesser (IFIAS 1974) to


standardize methods and bring together common research (Gilliland 1978).


In 1974,


the U.S. Congress passed a public law requiring net energy analysis to be a


consideration in the evaluation of federal project proposals.


There have been many


and often divergent schools of net energy analysis, some measuring only direct uses

(process analysis) and others measuring both direct and indirect sources or the


"embodied energy" supporting production.


Spreng (1988) reviews the different


approaches.

Two prominent approaches are contrasted by Brown and Herendeen (1995).

Embodied energy analysis, using input-output matrix techniques (Hannon 1973,

Herendeen and Bullard 1974), assigns resource flows from outside a system to

pathways inside according to carrier data such as materials or energy, but more often


money.


This method assumes that embodied energy is a conservative quantity


(Costanza 1980).


Odum (1983, 1995a) argues that the assumption of conservation


violates the second law since embodied energy disappears when the availability of the

transformed products is used up, and that materials, money, energy and embodied

Ansrovr ha AiWffArpnt dictrihitinnc rseciltino frnm different nrincinles: of circulation


Power and Society.





26

The method used in this dissertation, net emergy analysis, recognizes that

systems have interconnected and interdependent pathways that couple energy inflows


from outside (Odum 1995a).


Here, co-products are assigned the emergy input to that


subsystem or pathway before it "diverges."


Pathways are partitioned only if the same


product or flow is divided such as electricity going to individual users or sunlight


being captured by different canopy layers of a forest.


Emergy assigned to co-products


can not be added if the co-products converge elsewhere in the system or when


pathways feed back to amplify original sources (Odum


1995).


1995a; Brown and Herendeen


Because of the differences in theoretical underpinnings and methodology,


results from the procedures cannot be directly compared.


Examples are given next.


Previous Net Energy Studies of Biomass and Fuels


There is a large and growing body of literature on net energy studies of


biomass.


Slesser (1987) outlines a general procedure.


Smil (1983) and Boyles (1984)


review earlier studies.


Critics are as numerous as the myriad of different approaches


(Leach 1975; Reaven


1986; Jones 1989; Odum 1995a).


Most studies of net energy of


biomass systems are currently either process analyses of specific systems or some

version of input-output analysis for estimating embodied energy using regional or


national statistical data (Slesser 1985).


The quality of energy inputs is both ignored


(Boyles 1984) and addressed using various conversion factors, such as energy


intensities (Bullard et al.

1 OR0 FJ'l,'l at ol 1 QQ'n


1978; Herendeen 1981) and energy coefficients (Pimentel


iirhirh *actmata inm irt aMnarnioc A1i-rntlxr AotnrrniaAo kr fh







Environmental and climatic energy sources are generally not included (Slesser 1985),


and labor is variously measured (Fluck 1981) or not at all (Stanhill


1983).


The first


international workshop on energy analysis (IFIA


1974) recommended not evaluating


labor for industrial applications.


Ratios of net energy include


gross


energy requirement (GER) per unit


production (Leach and Slesser 1976); energy return on investment (EROI; Hall et al.


1986);


and net/gross


energy ratio (N/G; Herendeen and Brown 1987).


Currently there


is no convention and indices are variously defined, some including inputs others

ignore; some using conversion factors to address indirect sources that others leave out.

Some examples follow.

The FEA/USDA (1976) published a database of agricultural production and


(direct) energy consumption for each of the 50 states. Efficiency o

production was studied by Herendeen (1973). Fluck et al. (1992) a

consumption model for 60 agricultural systems in Florida. Other r

agricultural energy studies have been published (reviewed in Smil

Peters et al. (1981) reported an output/input energy ratio of


from forest residues in Canada.


)f energy use in crop


developed an energy

regional and national

1990).


6 for electricity


This ratio increased to 6.9 when generated electricity


used in the co-generation power plant was subtracted as inputs.


Marks (1990) reported


favorable economic and energy returns on investment for using wood powder as a fuel


in district heating plants in Sweden.


Hetz and Sonesson (1993) reported an


output/input ratio of 7.4 for grass production and 2.9 for biogas.


Detailed studies of


cbnrt.-r/atinr n wnillrnrw nlantainnc fr fuualiartn nrrthl-tnn rlruInlntsa ftl nritnt/innut







ratio of 19.3 (Sonesson


1993).


This study is compared with an emergy analysis of


willow production undertaken in this dissertation.

Herendeen and Brown (1987) summarize four earlier net energy studies of


woody biomass production.


Output/input ratios for harvested biomass increased from


12 to


as rotation


ages


increased from 6 (Eucalyptus spp.) to


5 years (Populus


spp).


When fertilization and artificial drying of the woodfuel was included, the


respective ratios declined to 2.5 to 3.4.


and 2


The author's analyses of 3 mixed hardwood


pine forests under rotations between 30 and 120 years in southern Illinois


calculated energy output/input ratios from 36.9 (for

43.4 (30 year old pine), declining with rotation age.


120 year old mixed hardwoods) to

Comparing the two sets of


analyses, however, Herendeen and Brown (1987) concluded that their calculation of

energy ratio (i.e., output/input ratio) increases with rotation age (this study is re-

evaluated using emergy analysis and the results are compared in the discussion section

of this dissertation).

Hall et al. (1986) document declining energy return on investment (EROI) for


domestic and imported natural gas and liquid petroleum during this century.


Using


input-output techniques, Cleveland and Costanza (1984) report net energy yield ratios


and lower for recovered geo-pressured gas in the Gulf Coast region of the U.S.


Much higher net yields were measured for natural gas and from gasification of coal.



Previous Net Emergy Studies of Biomass and Fuels


Orlim In1( QRIA\ n/rupnulxxluc amirav tnalaci vc 2rnnlii' fn nornfnr ct cucftmc


Flarlv





29

Swaney's (1978) evaluation of climatic inputs to agriculture; a study of agricultural and


natural systems in Gotland, Sweden (Jansson and Zucchetto

plantation pine in New Zealand (Odum and Odum 1979) an


1978); and evaluations of


id ethanol from sugar cane


in Brazil (Odum and Odum 1984).

Studies of agricultural production systems generally indicate high emergy


investments and low emergy yield ratios.


Brown and McClanahan (1992) documented


a reduction in the emergy yield ratio of Thailand rice from 3.9 to 1.5 with increasing


industrialization.


King (1991) calculated an emergy yield ratio of 1.1 for industrial


corn and commented that the ratio would be reduced if aquifer recharge were


accounted for.


Odum (1984) argued that agricultural crops have lower net emergy,


more similar to industrial and manufactured products, and cannot replace current fossil

fuels or woody biomass fuels which have higher emergy yield ratios.


Wood fuels and forests have been variously studied to date.


(1991) calculated an emergy yield ratio of


from wood.


Sundberg et al.


for 18th century charcoal production


Comar (1993) tracked emergy requirements for logging and wood


products industries in the central Amazon.


An earlier study of the Amazon and a


wood-fueled electricity plant in Jari (Odum et al. 1986) calculated an emergy yield


ratio of 12 for old growth logs.

studied by Keller (1992). Hool


industry in the U


Alternative treatments for pulp mill effluent were


kous (1995) evaluated the lumber and construction


Odum (1995b) reported emergy-based options for tropical forests.


Brown et al. (1995) evaluated alternative energy options for primary use and


transportation for Florida.


Emergy yield ratios for non-renewable fossil fuels range







shale oil in Colorado (Gardner


1977


Odum


1995a).


Brown et al (1993) calculated an


emergy yield ratio of 11 for Alaskan oil.


King and Schmandt (1991) reported yield


ratios of 10.3 for onshore natural gas, 6.8 for offshore gas,


3.2 for crude oil in


4.7 for coal methanol and


Texas.


Since electric power requires more transformation than most fuels, net emergy


yield of electric power is usually less than that for fuels.


For example, an emergy


yield ratio for lignite-fired electricity measured


(Odum et al.


1987).


Electricity


from solar voltaic power had a yield ratio less than unity (King and Schmandt 1991).



Forest Systems Evaluated in This Study



Physical and environmental measurements of the agroforest ecosystems


evaluated in this study are given in


Table


ordered by rotation age (i.e., cycle time).


Production and stored biomass are given as well as mean quantities harvested per


hectare per rotation period.


Energy content and specific density for woody biomass


are used to convert mass and volume biomass estimates to energy units.


These


parameters along with rainfall and estimates of evapotranspiration form the database


for evaluations of forest production and storage.


Other site specific management and


resource-use data are detailed individually for each system evaluation.

Systems range latitudinally from boreal forests in Sweden to tropical forests in


Papua New Guinea.


Cycle times range from 4 and 6 year rotation schedules for


fuelwood plantations to 200 and 300 year old growth forests under natural rotations.



















NO
S0-
0 00


-e (


1 rC i c 00c en 0
- --o- oNoo s


. ^
'0 0


N
00 0 0r


-O
Oa n
o N ^


00
Sn


-In


7
"*
M amat C ha L.s La R As 7


1-h


sumd 572 M






32

placed on forests of Sweden and Puerto Rico, the systems visited and studied in detail.

Other evaluations are drawn from current literature with citations given for each agro-


forest system.


Item numbers refer to


Table 3.


In Puerto Rico, five tropical forest ecosystems were studied:


four forest types


in the Luquillo mountains of eastern Puerto Rico (reviewed in Lugo and Scatena

1995); and the dry forest of Guanica on the southwestern coast (reviewed by Murphy


et al.


1995).


Physical, environmental and production data are summarized in Doherty


et al. (1994).


Generally, as elevation increases, cloud cover, cloud water interception,


annual precipitation and runoff increase while solar insolation, evapotranspiration and


above ground biomass decreases.


Mean age of the forest, used here as cycle time and


estimated from the quotient of stored biomass to annual accumulation rates (Weaver


and Murphy


1990; Doherty et al.


1994), also increases with elevation from 50 years in


low elevation systems to


170 years in montane forests.


The ecosystems of Luquillo Experimental Forest, a national forest managed for


research and recreation, were categorized


as 4 forest types (Brown et al.


1983).


elfin cloud forest (item 18), occurring above 900 m, receives water from both rainfall


and cloud interception.


production.


It has high runoff, low evapotranspiration and low annual


The colorado forest (item 11), a premontane forest dominated by Cyrilla


racemiflora, occupies mid-elevational areas (600-900 m).


The ubiquitous palm forest


(item 6), dominated by mountain palm, Prestoea montana, occurring in poorly drained

areas at both mid and low elevations, has the highest recorded production rate among





33

Dacryodes excelsa, has high production, rapid turnover and high forest


evapotranspiration rates.


The Guanica dry forest (item 8), lying in the rain shadow of


the island's central cordillera, receives mean seasonal rainfall of less than 860 mm


annually.


This forest type has lower net productivity, above ground biomass and


diversity than the other forest types receiving higher rainfall.


These systems are used


in this study as examples of mature forests under natural rotations and ones not

managed for timber extraction.

In Sweden, the most common trees species are spruce (Picea aibes) and pine


(Pinus silvestris) both occurring almost all over the country.


Birch (Betula spp.) a mid


successional species, is the most common deciduous tree in the country, commonly

to 20 percent of the standing stock in spruce/pine complexes (Kempe and von


Segebaden 1990).


Together, these dominant tree species compose the northern


coniferous forests studied here.


Above ground, annual growth ranges with increasing


rainfall, mean temperature and longer growing seasons from less than


ton/ha/yr in


northern and mountainous areas to 3-4 tons/ha/yr in southern Sweden (Eriksson and


Odin


1990).


Standing stock varies with location and management prescription and can


range from


25 tons/ha in the far north above the Arctic Circle to


180 tons/ha in old


growth stands of spruce in the south (Kempe and von Segebaden 1990).


Nilsson


(1990) gives a thorough overview of Sweden's forests, environmental conditions

affecting production, growing stock estimates, historical and current uses, industries,

and future projections.

Mnrth.rkn, narCirntur ,c fnrnctc in ertiithom Crnrlpn umnrAr I rliffsrsnt manaogrmnnt







type, managed spruce/pine stands (item


12) are harvested on average every 80 years


and routinely thinned during the growth cycle.


Silviculturall


managed forests yield


on average 3.82 tons/ha/yr above ground biomass with average standing stock just


over 100 tons/ha/yr.


About


of production is harvested.


Unmanaged mixed


coniferous forests (item 15), naturally self-thinned and reseeded with a higher

percentage of deciduous birch, were estimated to require an additional 20 years to

reach a mature steady state. Net production estimates were lower (3.19 tons/ha/yr)


since more gross production is channeled into maintenance and there is lower volume


of usable wood.


An old growth stand of spruce (item


19; Lundmark


1990) was


estimated at 200 years old with a mean biomass accrual rate, estimated as the quotient


of standing stock to age, of less than


ton/ha/yr.


These forest systems were evaluated


for silvicultural and harvest requirements, and form the basis for woodfuel, pulp and

paper evaluations.

Evaluations of forest rotations in the Shawnee National Forest in southern

Illinois were based on an earlier analysis by Herendeen and Brown (1987).


Silviculture, harvest, and production data based on yield tables,


each of five forest management schemes from U.S.


were complied for


Forest Service data (1982).


Loblolly pine (Pinus taeda) forests under 30 and 90 year rotation schedules (items


and 14, respectively) were compared with mixed hardwood forests (oak-hickory) under


60, 80 and 120 year rotation schedules (items 10,


13, and 16).


Net productivity of pine forests is greater than that of mixed hardwoods, and


nrnlirLttii't1r rrinrallir inprrACPC inth 0 Atraf


Anrnial n~r/\/ti ntirn ratC ActimatP f'rtm


I





35

averages 3.5 tons/ha/yr for mixed hardwoods and 7.3 tons/ha/yr for pine forests. Mean

biomass harvested, including volume from thinning schedules, increases for each forest

type with increasing rotation age and averaged 67% of production for both pines and


mixed hardwoods.


under


A slash pine (Pinus elliottii) plantation in north Florida (item 5)


25 year rotations had higher annual production than the 30 year old stand of


loblolly pine in Illinois, but a lower percentage of biomass was harvested (38% of

production; Gholz et al 1986).


Two tropical forest systems were evaluated:


a 140 year old lowland tropical


rainforest in New Britain, Papua New Guinea (Doherty and Brown 1992) and a 300


year old rainforest in Jari,


Brazil (revised from Odum et al.


1986).


These systems


recorded the highest rate of average annual production and


largest volume of stored


above ground biomass, estimated from published literature on tropical forests.


Forest


data in Papua New Guinea (item 17) were collected from a 20,000 ha logging

operation, removing 48,000 tons of lumber quality wood per annum (Tickell personal

communication 1990), averaging 148 tons/ha or just 39% of standing stock, due to


difficulty of terrain and a low percentage of marketable timber (Davidson


1984).


Brazil, a 2300 ha rainforest was cleared to produce 0.61 million tons of chipped


fuelwood to supply a 53 MW capacity electric plant.


This amounted to


262 tons/ha


woody biomass removed; an estimated


75%


of standing biomass (item 20).


Four short rotation fuelwood plantations were analyzed:


plantation in southern Sweden (Doherty et al.


a willow (Salix spp.)


1993; item 1); a mixed fuelwood


nlnntattin flunnalvntuv cnn and AMlalPniorn cnn l in nconth Florida (WanQ et nal


1981:





36

(NEA/FEP 1990; item 3); and an experimental siris plantation in Puerto Rico (item 4)


used to foster reforestation.


Plantations were harvested on 4 to


year schedules


yielding on average from 88-95% of above ground production.


Each plantation had


intensive silvicultural management including planting, fertilization, mechanical or


chemical weeding, and irrigation.


Plantation productivity and fuelwood yields are


higher than their counter part older growth forests of the same region.



Dissertation Plan


A central theorem investigated in this dissertation is the general thermodynamic

concept that net resource yield or net contribution of a production process is inherently


dependent upon time of growth.


Quantitative theory and assembled data from different


agro-forest production systems were evaluated to determine, among other postulates,


the net resource yield per cycle time of the product.


Data from forest production and


utilization systems in Puerto Rico, Sweden and other areas were evaluated and


compared using emergy analysis techniques.


General relationships of emergy yield


ratio, investment ratio, maximum empower and thermodynamic minimum

transformities were explored using systems evaluations and computer simulation.

Forest systems evaluated for production and harvest yields are presented first.

These include northern coniferous forests in Sweden; loblolly pine and mixed

hardwood forests of Illinois; slash pine stands in Florida; a secondary rainforest in


Pna7nrra\liiairtnnc eFiialixun/Al nlntatlQnnc in xvwwln r1lnri;a canA


T^QTilQ MOIIr T /^lllMOO







for biomass production and storage.


are presented.


Evaluations of forest multiple-uses and services


Analyses of non-market services of carbon sequestration, regional water


supply and reforestation are followed by analyses of woodfuel development for district

heating in Sweden, of pulp and paper industries, and of tourism in a national forest of


Puerto Rico.


Electricity evaluations are next.


Electricity generation using


conventional primary fuels (4 substation generator plants in Gainesville, Florida, and 4


existing operations in


Thailand) are followed by 4 examples of wood-fueled electricity


production.

Computer models are presented to simulate concepts of net yield and cycle

time, thermodynamic minimum transformities for forest production, and maximum


empower.


Emergy-based measures of value are presented to place the multiple roles


of forests into the regional economy and compare with market values.


The results of


these analyses were then used to address public policy questions concerning energy


delivery systems, sustainable uses of forest resources, and forest values.


The capacity


of biomass fuels to compete with existing non-renewable sources and limits for

civilization after the decline of fossil fuels are discussed.











METHODS



General methods are given for evaluation of agroforest production and

utilization systems, for deriving indices of comparison, and for computer simulation of

a general production and yield models.



Emerev Systems Evaluations


In general, all systems were studied with similar methodology (steps A-C) each

described in overview below followed by more detailed descriptions.


Energy systems diagrams for each of the agroforestry and resource-use
sectors studied were computer drawn as a way to gain an initial network
overview, combine information of collaborators, organize data-gathering
efforts, and better understand concepts, ecosystem functions and system
configurations.


Resource evaluation tables were set up to facilitate calculations of main


sources and contributions to each system studied.


Resource inputs and


production yields are reported in each table in physical accounting units (tons,
joules, $, etc.) and then converted to common units of solar emergy (solar
emjoules) to facilitate comparisons between systems.

Ratios identifying resource origins and system efficiencies, and indices
relating solar emergy measurements to market economic values were


calculated for each system.


summarized in


All measurements and resultant indices were


systems diagrams accompanying each emergy evaluation


table.







Energy Systems Diagramming


Using energy circuit language (Odum


1971, 1988) systems diagrams were


drawn for all resource production, storage and utilization systems studied in this


dissertation.


The diagramming steps followed for each system are given below:


1. The boundary of the system was defined.

2. A list of important sources (external causes, energy and material factors, forcing
functions) was made.

3. Considering the scale of the defined system, a list was made of principal
component parts believed important.

4. A list was made of processes (flows, relationships, interactions, production and


consumption processes, etc.).


Both resource flows and monetary transactions


were included.

5. Energy systems diagrams and models were developed using the following


conventions of energy language diagramming (from Odum


Symbols:
(Figure 2).


System Frame:


, 1988):


The symbols each have rigorous energetic and mathematical meanings


A rectangular box is drawn to represent the boundaries that were


selected.


Arrangement of Sources:


Any input that crossed a boundary was


identified as a


source, including pure energy flows, materials, information, human services, as


well as inputs that were destructive.


symbol.


All source inputs were given a circular


Sources were arranged around the outside border from left to right in


order of their solar transformities starting with sunlight on the left and
information and human services on the right.


Pathway Line:


information.


Flows were represented by lines including energy, materials and


Money was identified with dashed lines flowing in opposite


direction of energy flows.


Outflows: Any outflow which still had available potential energy, material more
concentrated than the environment, or usable information was identified as a







Degraded Energy:


Energy that had lost its ability to do work according to the


second law of thermodynamics was represented as pathways converging to a heat


sink at the bottom center of the diagram.


Included was heat energy as


byproducts of processes and the dispersed energy from depreciation of storage.


Adding Pathways:


Pathways added their flows when they joined or when they


went into the


same the storage tank.


Every flow in or out of a tank must be the


same type of flow and measured in the same units.


Interactions:


Two or more flows that were different, but were both required for a


process were drawn to an interaction symbol.


The flows to an interaction were


connected from left to right in order of their solar transformity.


The lower


transformity flow was connected to the notched left margin of the symbol.


Counterclockwise Feedbacks:


High-quality outputs from consumers such as


information, controls, and scarce materials were identified as reinforcement


pathways fed back from right to left in the diagram.


Feedbacks from right to left


represented a loss of concentration because of divergence.


Material Balances:


Since all inflowing materials either accumulate in system


storage or flow out, each inflowing material such as water or money had


outflow pathway


identified and drawn.


The diagrams were then simplified through aggregation of important categories


that were quantified in the emergy evaluations.


A systems diagram accompanied each


evaluation summarizing the computations, identifying emergy values and certain

physical values for sources and resource yields and listing resource indices for each


transformation step.


Generally diagrams included source inputs (cross boundary flows)


to be evaluated including environmental inflows (sun,


wind, rain, rivers, and geological


processes, etc.); economically derived resources (fuels, minerals, electricity, foods,


fiber,


wood); human labor and indirect services; monetary exchanges; and information


flows.

includes


Export flows were also drawn.


Components inside the system boundary


the main land use areas; large storage of fuel,


water, and soil; the main


1:





41

circulation of money was not drawn, but all the major flows of money in and out of

systems were included.



Emerev Evaluation Tables


All systems studied were analyzed using emerge evaluation tables with


calculations of inputs and summaries of solar emergy indices given as footnotes.


table was presented similarly, with


Each


columns, each with the following headings:


Resource


Solar emergy


Solar


Footnote


units


(J, g, $)


per unit
(sej/J, sej/g, sej/$)


emergy


Column One is the line item number identifying the footnote at the end of the table
where the source of the raw data was cited and calculations shown.


Column Two is the


name of the item being evaluated,


which was also identified on


the accompanying systems diagram.


Column Three contains flows or storage, given in physical units (joules, grams, or
dollars) reported by industry accounting or obtained from published literature and


statistical abstracts.


These are reported either as average annual flows per unit


volume or area or per unit output.


footnotes (column 1).


References and calculations are identified as


For example, forest production was reported as tons or solid


cubic meters per unit area per unit time (tons/ha/yr or m'/ha/yr).


were reported as (liters/ha/yr).


Inputs such as fuel


Inputs for other systems were evaluated per unit


output such as per MWh electricity produced (J-fuel/MWh-electricity) or labor cost


per ton of woodfuel produced ($/ton-wood powder).


Evaluations of storage were


reported per unit stored (J/ha or J/ton).

Column Four lists the solar emergy per unit for each line item used to convert


physical units in column 2 to units of solar emergy.


These include solar emjoules


per joule, sej/J (i.e., solar transformity) or sej/gram or sej/dollar.


These were


-\ I .. .1 f





42

Column Five is the solar emergy of the resource input, product or storage, measured
in solar emjoules per time (sej/ha/yr) for emergy flows, emergy per unit output
(sej/ton, sej/MWh), and emergy per unit area or volume (sej/ha, sej/ton) for


storage.


It is the product of columns 3 and 4.


Emergy values were reported in


tables and figures as either E+12 or E+1 8 sej/unit to facilitate computations and
comparisons between systems.


Inputs and yields for evaluated sectors were identified on each emergy

evaluation table and in the text and footnotes using a similar notation (refer to Figure


Aggregations of environmental inputs were identified as (I); each set of


purchased inputs associated with a particular process step (i) was summed and labeled

as (F1); yields or outputs for each transformation step (i.e. total contributions, defined

as the sum of all inputs) were identified as (Y1) for annual flows or (Q1) for stored


quantities for each transformation step.


In general for all agro-forestry systems


evaluated, above ground forest production was denoted (Y1); harvested biomass

(process step 2) was identified (Y2).

Solar transformities derived from these evaluations were indexed in the tables


by ST,.


This was done in order to separate referenced solar transformities derived


from other studies and those that were calculated from evaluations in this study.


Process step summations (Ii, F


Y,) and computations of transformities (ST,) were


listed as corresponding footnotes below each table.

Renewable environmental energy sources supporting biomass production (R)

were estimated from the chemical potential energy of incident rainfall, measured as


Gibbs free energy of the portion of rainfall that is evapotranspired.


This was a


surrogate input measured to include all other renewable energies including solar






sources.


Because the calculation of transformities for these coupled sources are all


based on the global budget of available solar emergy, adding together their calculated


emergy values would double count source inputs.


Evapotranspired rainfall for all


evaluated agroforest systems had the largest calculated emergy value and was used to


account for all coupled environmental sources.


Surface water supply, split from


incident rainfall as runoff, was included in the analyses of other ecosystem services.

Nonrenewable environmental sources (N) of top soil and minerals were evaluated

separately.

An estimate of the emergy support base of human services was made using the

emergy/money ratio for the region and year of production, multiplied by the market


cost or value of a commodity or service.


The money paid for machinery, fuels and


other goods necessary in a production sector pays for the human services involved in


the refinement, manufacture and delivery of the commodity.


The emergy/money ratio


was used to assign an emergy value to human services in proportion to the money paid

for the service, assuming that each dollar paid for a product or service represents a

proportional amount of emergy supporting the direct and indirect human labor

requirements.


An average emergy base for


wages


earned was considered an estimate of the


lifestyle support requirements of both the laborers as well


as the associated human


services that produce and deliver the commodities used in production.


If only labor


hours were known for a production sector, a solar transformity for human ergonomic

work was estimated (documented in footnotes) and multiplied by metabolic





44

Resource Indices and Synthesis


From the emergy evaluation tables, comparative indices of resource origins,

allocations, exchange, and relations to macro-economic valuation were calculated to

draw inferences and cross-system comparisons which were used as tools for making


decisions regarding energy policy and public and ecosystem welfare.


included:


These measures


net emergy yield, emergy yield ratio (YR), emergy investment ratio (IR),


emergy exchange ratio (ER), environmental loading ratio, emergy/monetary cost ratio


(i.e., emergy/dollar ratio) and the emdollar value of resources


(refer to


Table


Figure 4 for definitions).

The emdollar values (em$) for current year of production for resources or

ecosystem services were calculated as a biophysical estimate of macro-economic


(public policy) value.


This measure is an estimate of the portion of gross economic


product for a region attributed to the resource or service (Table 1).


The emdollar


value was compared with market values of forest products and with other estimates of

marco-economic value for non-market forest commodities and services.

Relationships and trends of production rates, investments, net yields,

transformities and replacement time derived from the emergy evaluations were graphed


as simple regressions addressing hypotheses.


Together, resource indices, emergy


summations, and graphical analyses were used to synthesize evaluations and discuss

alternatives regarding forest resource-use and energy policy.





45

Computer Simulation



Computer models were developed to investigate general ecosystem principles

regarding the relationship of forest turnover rates and indices of net emergy yield and


investment.


Empirical data from emergy evaluations of forest systems and from


literature sources were used to test hypotheses and verify thermodynamic relationships


evidenced from the analyses.


Energy circuit language and the resulting system


diagrams were mathematically defined with differential equations drawn from the

model configuration, orientation of components and the relationships identified in the


diagrams (Odum


1983).


Conceptual models were drawn, state variables were identified, and


mathematical expressions were written for interactions and processes.


Models were


calibrated using data from the analysis of silviculturally grown spruce/pine forests.

Using spreadsheet iterations, steady state values were determined for above ground

biomass of a mature forest and coefficients were calculated for each interactive

pathway (i.e., mathematical expressions identifying relationships of two or more state

variables over time).

Equations were then written into BASIC computer language and simulated to

investigate changes over time with changes in inputs or state variables using the


constructed computer program.


By first identifying the baseline calibration at steady


state, the effects of changes in system configuration could be investigated by changing


one variable at a time in the program.


Graphs were obtained from the computer











RESULTS



Emergy systems evaluation of forests and their utilization are given next


including carbon sequestration, biomass storage,


water supply, recreation, and


production of market commodities of lumber, pulp, paper and fuelwood.


Net emergy


evaluations of electricity generation alternatives follow.



Emerev Evaluation of Forest Productivity and Extraction


Forests of Southern Sweden


Boreal spruce/pine forests in southern Sweden were evaluated for silvicultural


production and timber harvest (Table 4).


Under 80 year rotation schedules, about


of average above ground production (3.82 tons/ha/yr) is harvested annually.


Environmental sources accounted for


92%


of inputs to silvicultural production.


Economic sources (F, and F2) measured 40% of inputs to harvested biomass.


A solar


transformity for silviculturally managed forest production (ST,) measured 4930 sej/J,


more than doubling for harvested biomass (Figure 8). The emergy yield ratio declined

80% from standing crop (YR,) to harvested biomass (YR4). An emergy investment


ratio for harvested biomass (IR) measured 7 times greater than standing crop (IR1).

Analyses were also made of 100 and 200 year old unmanaged boreal forests,





47

Table 4. Emergy evaluation of boreal spruce (Picea aibes) and pine (Pinus silvestris)
silvicultural production and timber extraction under 80 year rotation schedules


in southern Sweden.


" Analysis is summarized in Figure 8.


Resource
units/ha/yr
(3, g, $)


energy
per unit


Solar energy
flow
(E+12 sej/ha/yr)


Environmental sources:


Sunlight
Wind, kinetic


Evapo-transpired rain


.57E+13


8.73E+10 J
1.95E+10 J


18200


130.9
355.1


Silviculture:
4. Motor fuel


5.59E+07 J


Tractors, trucks
Human services


18.70 $


47900


6.7E+09
1.5E+12


,Above ground production


(3.82 tons/ha/yr)

Harvesting:


Motor fuel


7.84E+10 J


5.97E+08 J


, 386.3


47900


Feller, forwarder


9. Human services
10. Capital investment


101.26 $
14.44 $


6.7E+09
1.5E+12
1.5E+12


151.9
21.7


Harvested biomass
(2.85 tons/ha/yr)


5.85E+10 J


589.7


Summary of measurements:

Solar transformitv:


Above ground production


Harvested biom ass


Emergy yield ratio:
YR, Above ground production


10,083


12.39


Harvested biomass


Emergy investment ratio:
IR1 Above ground production
IR, Harvested biomass








Table 4--continued; notes.
a. Analysis based on an average spruce/pine forest production of 8.989 m3/ha/yr, harvesting 74.6% of
production (6.704 m3/ha/yr) in southern Sweden (based on an 80 year, steady state rotation)
(Doherty et al. 1993).

b. Inputs calculated as available energy are multiplied by solar transformities (sej/J) to obtain solar
emergy; inputs reported as mass use sej/g;, monetary inputs use sej/$ for regional economy and year
of production (Table 2 unless cited otherwise in footnotes).

1 Environmental inputs:


Solar energy


= (area) (avg insolation) (1-albedo)


cm2/m2) (4186 J/kcal) (1


- 0.28)


= (10,000 m2/ha) (85.4 kcal/cm2/yr) (10,000


= 2.57E+13 J/ha/yr


Wind, kinetic energy


= (Vertical gradient of wind)2 (hgt of atmospheric boundary) (density of


air) (eddy diffussion coefficient)


(1 ha) (sec/yr)


= [(3.0 m/s)


(1000 m)]


(1000 m) (1.23


kg/m')


m2/sec) (10,000 m /ha) (3.154E+7 sec/yr)


= 8.73E+10 J/ha/vr


Rain, chemical potential energy


= (area) (rainfall) (% evapotrans) (Gibbs free energy)


(10,000m2/ha) (0.80m) (0.49) (1000 kg/m') (4.94E+3 J/kg)


= 1.95E+10 J/ha/vr


Inputs to silvicultural management:
scarification:
planting:
stand regulation:
ditching:
roads:


fuel (liters/ha/yr)


machines


(g/ha/yr)


Total:


Motor fuel


1/ha/yr


= (1.57 liters/ha/yr) (35.6E+6 J/l)


g/ha/yr


= 5.59E+7 J/ha/yr


Machinery depreciation [given as %wgt (g)]


= (0.1 operating hrs/ha/yr)


(15,000 hrs useful


life) (10 ton trucks, tractors) (IE+6 g/ton)


= 66.4 g/ha/yr


Human services


(total


cost of production)


= (13.5


SEK/m')


(8.989


m'/ha/vr)


(6.50 SEK/$US,


1988)


= 18.70 $/ha/yr


, Above ground production


= (9.0 m3/ha/yr) (0.425E+6 g/m3) (2.052E+4 J/g)


= 7.84E+10 J/ha/yr


Harvesting:
7. Motor fuels


= (2.5


liters/m3) (6.704 m'/ha/yr) (35.6E+6 J/liter)


= 5.97E+08 J/ha/vr


Feller and forwarder depreciation [given as %wgt. (g)


0.07 operating hrs/m')


15,000 hrs


useful life) (6 tons) (1E+6 g/ton) (6.704 m'/ha/yr)


= 187.71 g/ha/yr


Human services = [(Direct


costs


SEK/m3)


costs 12.1 SEK/m3) + (depreciation 14.0 SEK/m3)


- (silv. prod.


= (98.2


costs 13.5


SEK/m3


SEK/m')] + (indirect
Sm'/ha/yr) / (6.50


SEK/$US, 1988)


= 101.26 $/ha/vr


10. Capital cost of machines = (6.7 mi/ha/yr harvest) (0.07 hrs/m3) (0.47 hrs/ha/yr) (200.0 SEK/hr


capital costs)


= (93.9 SEK/ha/vr)


(6.50 SEK/$US. 1988)


= 14.44 $/ha/vr


#







Table 4--continued.

Summary of measurements:


Item 1 = 355
Items 4+5+6


.14E+12 sej/ha/yr
= 31.17E+12 sej/ha/yr


Items 7+8+9+10


= 203.50E+12


/ha/yr


= 386.30E+12 sej/ha/yr


I+F1+F


= 589.70E+12 sej/ha/yr


Solar transformities


= Y, (sej/ha/yr) / Y,


J/ha/yr):


Above ground production


= (3.86E+14 sej/ha/yr) / (7.84E+10 J/ha/yr)


= 4928 sej/J


Harvested biomass


= (5.65E+14


sej/ha/yr) / (5.85E+10 J/ha/yr)


= 10,083 sej/J


Emergy yield ratio


= Y / (F,+... F,):


YR, Above ground production


= (386.30E+12 sej/ha/yr) / (31.17E+12 sej/ha/yr)


= 12.39


Harvested biomass


= (589


.70E+12


sej/ha/yr) / (31.17 +179.07)E+12 sej/ha/yr


= 2.51


Emergy investment ratio


= (F,+... F,) / I:


Above ground production


= (31.17E+12 sej/ha/yr) / (


355.1E+12 sej/ha/yr)


= 0.09


Harvested biomass = (31.17 + 203.50)E+12 sej/ha/yr / (355.1E+12 sej/ha/yr)


= 0.66
































Environ-
mental
sources


Boreal
forest


386.3


(3.82 tons/ha/yr)


151.9


21.7


589.7


85 tons/ha/yr)


E+12


Above ground
production


sej/ha/yr


Harvested
biomass


Solar transformity
Emergy yield ratio


4928
12.39


10,083


Emergy investment ratio


S4 ** I *4 4 4 *


Harvest


( Goods,
vServices/


__,1





51

be necessary for forests in southern Sweden to mature after clear cutting if no planting


or silviculture was applied (Figure 9a).


While approximately


75% of annual above


ground production is harvested in managed forests, only 67% of stored biomass (Q1


120 tons/ha) is harvested (Q, = 80.6 tons/ha) in natural forests due to a higher

percentage of dead and diseased wood. Solar transformities for stored and harvested


biomass were both higher in unmanaged forests than in managed stands due to 20

additional years of environmental emergy sequestered through production (Figure 9a).


Harvest emergy,


71.4E+12 sej/ton, measured 3% of total inputs.


An emergy yield


ratio of 4.1


for harvested biomass was 1.6 times greater than the emergy yield ratio for


harvested biomass from managed stands.

Two-hundred year old growth spruce ecosystems with 188.0 tons/ha above

ground biomass had the largest solar transformity measuring 9573 sej/J, almost twice


that for biomass production in managed stands (Figure 9b).


It was assumed that


usable wood from old growth averaged ten percent lower (60% compared with 67%


for younger forests) yielding 112.8 tons/ha stemwood.


Higher emergy yield ratios and


lower investment ratios indicate the surplus of environmental sources used in storing

biomass under longer turnover periods.



Forests of Southern Illinois


Five forest ecosystems in southern Illinois under different management

schedules were compared for annual production rates, silviculture and harvest emergy


expenditures (Table 5).


Using data from Herendeen and Brown (1987), loblolly pine










Economic


Natural forest
regeneration,


sources


Environ-
mental
sources


Boreal forest
(100 yrs)


(80.6 tons/ha)


E+15


Harvested


Above ground
biomass


mass


Solar transformity


7188 sej/J


14,243 sej/J


Emergy yield ratio

Emergy investment ratio


Biomass
(1880
tons/ha)


Old growth
ecosystem
(2O0 yrs)


(112.8 tons/ha)


Above ground
biomass


Harvested
biomass


Solar transformity


9200 sej/J


18,778 sej/J


Emergy yield ratio

Emergy investment ratio


*


r .. .---


Harvest


Economic
\sources


_ I i .. J _F -_ -


h







Figure 9--continued; notes.

Naturally regenerated forests:
Q, Above ground biomass of mature forest


= 283 m'/ha (mean stand volume in southern Sweden;


Nilsson personal communication):


(283 m'/ha) (0.425 tons/m3)


120.3 tons/ha (IE+6 g/ton)


(2.052E+4 J/g) = 2.47E+12 J/ha

Harvested biomass: utilized wood volume in self-thinned, unmanaged forests is about 89% of


silviculturally managed stands (Vikinge 1991) of which


of standing crop is harvested (Table


4), therefore 67% of production is est. harvested; (120.3 tons/ha; Q, above) (67%)


(1E+6 g/ton) (2.052E+4 J/g)

Environmental sources = (35
1.78E+16 sej/ha


= 80.6 tons/ha


= 1.65E+12 J/ha


>5.1E+12 sej/ha/yr; Table 4) (100 yr. rotation) (est. 50% used) =


Harvest subsidies


= (203.5E+12 sej/hayr) / (


2.85 tons/ha/yr harvested; Table 4)


= 71.42E+12 sej/ton (80.6 tons/ha harvested)


76E+15 sej/ha


Solar transformity for Q1


= (1.78E+16 sej/ha) / (2.47E+12 J/ha)


= 7188 sej/J


Solar transformity for Q2

Emergy yield ratio for Q2


= [(17.8 +

= (I + F,)


5.76)E+15 sej/ha]


/F


= F, / 12


Emergy investment ratio for Q2


(1.65E+12 J/ha)


= 14,243 sej/J


36E+16 sej/ha) / (5.76E+15 sej/ha)

76E+15 sej/ha) / (1.78E+16 sej/ha)


= 4.09

= 0.32


Old growth forests:
Q, Above ground biomass for old growth forest
tons/m3; Danielsson personal communication)
= 3.86E+12 J/ha


Harvested biomass:


= 400 m/ha (Lundmark 1990):


(400 m3/ha) (0.470


= 188.0 tons/ha (1E+6 g/tons) (2.052E+4 J/g)


(60% harvested; est. 10% lower than percent vol. harvested in 100 year old


stand); (188.0 tons/ha) (60%)


112.8 tons/ha (1E+6 g/ton) (2.052E+4 J/g)


= 2.32E+12 J/ha


Environmental sources


used)


= (355.1E+12 sej/ha/yr; Table R-l) (200 yr. turnover time) (est. 50%


= 3.55E+16 sej/ha


Harvest subsidies


= (71.42E+12 sej/ton) (112.8 tons/ha harvested)


= 8.06E+15


sej/ha


Solar transformity for old growth biomass (Q,)


= (3.55E+16 sej/ha)


(3.86E+1


= 9200 sej/J


Solar transformity for harvested old growth (Q4)
= 18,778 sej/J


= [(35.51 + 8.06)E+15 sej/ha


/ (2.32E+12 J/ha)


Emergy yield ratio for Q2


= (4.36E+16 sej/ha) / (8.06E+15


sej/ha)


= 5.41


Emergy investment ratio for Q2


= (8.06E+15 sej/ha) / (3.55E+16 sej/ha)


= 0.23


1


= (2.


= (I + F) / F,


= F, / I,







5. Emergy evaluations of typical loblolly pine and mixed hardwood forest
production and timber extraction under different rotation schedules in


Shawnee National Forest, southern Illinois.
in parentheses are average tons/ha/yr. Res4


calculations are given as footnotes for each rotation.


Values are E+12 sej/ha/yr; values


source units and emergy


Analyses are


summarized in Figure


Loblolly pine Mixed hardwoods
Note Item 30 years 90 years 60 years 80 years 120 years


I Environmental sources: 614.0 614.0 614.0 614.0 614.0

Fi Silviculture, management:
1. Minimum level mgt. 24.4 24.4 24.4 24.4 24.4
2. Road maintenance 14.8 14.8 14.8 14.8 14.8
3. Site preparation fuels 16.3 5.4 5.4 4.0 2.7
4. Site preparation services 44.1 14.7 14.6 10.9 7.3
5. Fertilization 7.5 0 0 0 0
6. Commercial thinning 0 11.4 2.1 3.5 2.8

Y1 Above ground production 721.0 685.0 675.0 671.0 666.0
(tons/ha/yr) (8.83) (5.83) (3.77) (3.55) (3.12)

F2 Harvesting:
7. Fuels 24.0 25.3 12.1 13.1 11.3
8. Machinery 3.7 3.9 1.5 1.7 1.4
9. Labor 249.0 262.0 125.0 136.0 117.0
10. Harvest preparation 8.0 8.0 8.0 8.0 8.0

Y2 Harvested biomass 1010.0 983.0 822.0 830.0 803.0
(tons/ha/yr) (4.55) (4.78) (2.29) (2.48) (2.14)


Summary of measurements:

Solar transformity (sej/J):
ST, Above ground production 4,075 5,863 9,834 10,399 11,740
ST, Harvested biomass 11,043 10,272 19,697 18,383 20,645

Emergy yield ratio:
YR, Above ground production 6.74 9.68 11.03 11.65 12.81
YR2 Harvested biomass 2.57 2.66 3.95 3.84 4.24

Emergy investment ratio:


Table





55

Table 5--continued; notes.

Data compiled from Herendeen and Brown (1987) unless cited otherwise in footnote calculations.


Wood characteristics


and production quantities are reported


as follows:


Forest


Rotation
period
(years)


Wood


density
(tons/m3)


Energy
content


(E+6 kcal/ton)


Above ground


Harvest


Thinning


biomass


(tons/ha/rotation)


(tons/ha/rot.)


(tons/ha/rot.)


Loblolly pine


Loblolly pine
Mixed hardwood
Mixed hardwood
Mixed hardwood


Evapo-transpired rain [assumed same for all forest rotations


136.5
279.9


150.7


in/yr; NOAA 1977) (64% ET;


est. using DeAngelis et al. 1981) (25.4 mm/in) / (1000 mm/m) (IE+4 m2/ha) (1000 kg/m3)


(4.94E+3 J/kg)


= 3.37E+10 J/ha/yr (18200 sej/J)


= 6.14E+14 sej/ha/yr


Silviculture:


Minimum level management, maintenance


reported same for all forest rotations]:


6.09 $/ha/yr


(4.0E+12 sej/$, U.S. 1978; Odum 1994)


= 2.44E+13 sej/ha/yr


Road maintenance [reported same for all forest rotations
= 1.48E+13 sej/ha/yr

Site preparation fuels:


3.71 $/ha/yr (4.0E+12 sej/$, U.S. 1978)


(2.43E+6 kcal/ha/rotation) (4186 J/kcal)
= 1.63E+12 sej/ha/yr
(2.43E+6 kcal/ha/rotation) (4186 J/kcal)


(30 yr. rotation)


(90 yr. rotation)


= 3.40E+08 J/ha/yr (47900 sej/J)


= 1.13E+08 J/ha/yr (47900 sej/J)


= 5.42E+12 sej/ha/yr


(1.16E+6 kcal/ha/rotation) (4186 J/kcal)


(60 yr. rotation)


= 1.12E+08 J/ha/yr (47900 sej/J)


= 5.38E+12 sej/ha/yr


(1.16E+6 kcal/ha/rotation) (4186 J/kcal)
= 4.04E+12 sej/ha/yr
(1.16E+6 kcal/ha/rotation) (4186 J/kcal)


(80 yr. rotation)


(120 yr. rotation)


= 8.42E+07 J/ha/yr (47900 sej/J)


= 5.62E+07 J/ha/yr (47900 sej/J)


= 2.69E+12 sej/ha/yr

Site preparation services:
a. (330.91 S/ha/rotation)
= 4.41E+13 sej/ha/yr


(330.9


18.88
18.88


(30 yrs)


S/ha/rotation) / (90


$/ha/rotation)
S/ha/rotation)


1.03 $/ha/yr (4.0E+12 sej/$,


= 3.68 S/ha/


yr (4.0E+12


sej/$)


= 3.65 $/ha/yr (4.0E+12 sej/$)
= 2.74 $/ha/yr (4.0E+12 sej/$)


U.S. 1978; Odum 1995)


= 1.47E+13 sej/ha/yr
= 1.46E+13 sej/ha/yr
= 1.09E+13 sej/ha/yr


(218.88 S/ha/rotation) / (120 yrs)


= 1.82 $/ha/yr (4.0E+1


sej/$)


.30E+13 sej/ha/yr


Fertilization [only applied on loblolly pine forests of 30 year rotations]:


(2.72E+06 J/ha/rotation)


(30 yrs) / (


83E+04 J/kg) (1000 g/kg)


1.55E+3 g/ha/yr


(4.8E+9


= 7.45E+12 sej/ha/yr








Table 5--continued.


(1.60E+04 kcal/ms) (4186 J/kcal) (320.60 m'/ha/rotation)


(90 yrs)


= 2.39E+08 J/ha/vr


(47900 sej/J)


= 1.14E+13 sej/ha/yr


(1.70E+04 kcal/m3) (4186 J/kcal) (36.40 m'/ha/rotation)


(60 yrs)


= 4.32E+07 J/ha


(47900


/J) = 2.07E+12 sej/ha/yr


(1.70E+04 kcal/m3) (4186 J/kcal) (81.20 m3/ha/rotation)


(80 yrs)


= 7.22E+07 J/ha/yr


(47900 sej/J)


= 3.46E+12 sej/ha/yr


(1.70E+04 kcal/m') (4186 J/kcal) (98.70 m'/ha/rotation) /


(120 yrs)


= 5.85E+07 J/ha/yr


(47900 sej/J)


= 2.80E+12 sej/ha/yr


Above ground production [estimates by Herendeen and Brown (1987) using known ratios of above


ground biomass to harvested wood


as follows: 1.94 (harvested biomass, Y, below) for rotations


30-60 yrs; and 1.88 for rotations > 90 yrs]:


(1.94) (136.5 tons/ha/rotation)


= 265 tons/ha/rotation


(30 yrs)


= 8.83 tons/ha/yr (4.78E+06


kcal/ton) (4186 J/kcal) =


1.77E+11 J/ha/vr


(1.88) (279.9 tons/ha/rotation) =


525 tons/ha/rotation /


90 yrs)


= 5.83 tons/ha/yr (4.78E+06


kcal/ton) (4186 J/kcal) =


.17E+11 J/ha/yr


(1.94) (116.4 tons/ha/rotation) =


226 tons/ha/rotation /


(60 yrs)


= 3.77 tons/ha/vr (4.35E+06


kcal/ton) (4186 J/kcal)


.86E+10 J/ha/yr


(1.88) (151.2 tons/ha/rotation)


= 284 tons/ha/rotation


(80 yrs)


= 3.55 tons/ha/yr (4.35E+06


kcal/ton) (4186 J/kcal)


.86E+10 J/ha/yr


(1.88) (199.


tons/ha/rotation)


= 374 tons/ha/rotation


(120 yrs)


= 3.12 tons/ha/yr (4.35E+06


kcal/ton) (4186 J/kcal)


= 5.67E+10 J/ha/yr


Harvesting:


Medium skidder, 17,158


kcal/ton + Chain


saw, 9167 kcal/ton


= 26,325


kcal/ton


(26,325 kcal/ton) (4.55
= 2.40E+13 sej/ha/yr


tons/ha/yr) (418


J/kcal)


.01E+08 J/ha/yr (47900 sej/J)


(26,325


kcal/ton) (4.78 tons/ha/yr) (4186 J/kcal)


= 5.27E+08 J/ha/vr (47900 sej/J)


= 2.53E+13 sej/ha/yr
(26,325 kcal/ton) (229 tons/ha/yr) (4186 J/kcal)
= 1.21E+13 sej/ha/yr
(26,325 kcal/ton) (2.48 tons/ha/yr) (4186 J/kcal)


= 2.53E+08 J/ha/yr (47900 sej/J)


= 2.73E+08 J/ha/yr (47900 sej/J)


= 1.31E+13 sej/ha/yr


(26,325 kcal/ton) (2.14 tons/ha/yr) (4186 J/kcal)
= 1.13E+13 sej/ha/yr


Machinery depreciation [given as


= 2.35E+08 J/ha/vr (47900 sej/J)


% wt. (g)]:


Tractor: (
Chainsaw:


Tractor:


Chainsaw:


0.08 hrs/m3)


(0.33 hrs/m')
(53.3 g/m3)


(3.37 g/m3)


(12,000 hr. life expectancy) (8


(2000 hr. life expectancy) (4


(0.47 tons/mr, wood density) (4.55
/ (0.47 tons/m3) (4.55 tons/ha/yr)


ton) (1E+6 g/ton)


Ibs, est. wt.) (453.6


tons/ha/yr, harvest)


= 53.33E+4 g/m'


I = 3.37 g/m3
= 524 g/ha/yr


= 33 g/ha/yr


Total depreciation


= (524 + 33) g/ha/yr


= 556


/ha/yr (6.7E+9 sej/J)


= 3.73E+12 sej/ha/yr


Tractor: (
Chainsaw:


53.3 g/m3)


(0.47 tons/m') (4.78 tons/ha/yr)


(3.37 g/m3) / (0.47 tons/m3) (4.78


Total depreciation


Tractor:


= (551 + 34) g/ha/yr


(53.3 g/m3) / (0.58 tons/m3) (2


tons/ha/y


= 551 g/ha/yr
r) = 34 g/ha/yr


= 585 g/ha/yr (6.7E+9 sej/J)


29 tons/ha/yr)


= 3.92E+12 sej/ha/yr


= 214 g/ha/yr


Chainsaw:


(3.37 g/m3)


tons/m3) (2.29 tons/ha/yr) = 13 g/ha/yr


Tntl Al4 n nroto fhnn = lilA 4- 1 2\ nIn I. -- 11 nt L O auT = 1


use:


- "'7" -,/I,/,, t'K "?T:-LQ /l,/


-1~ C1? <->Cl;- ^;/loA







Table 5--continued.


Tractor: (
Chainsaw:


g/m3) / (0.58 tons/m3) (2.14 tons/ha/yr)


(3.37 g/m3) / (0.58 tons/m3) (2.14 tons/ha/yr)


199 g/ha/yr
= 13 g/ha/yr


Total depreciation


= (199 + 13) g/ha/yr


= 212 g/ha/yr (6.7E+9 sej/J)


1.42E+12 sej/ha/yr


Harvest labor:


2.98 labor-hrs/ton, est. (Table 6, note 7):


Solar transformity for U.S. labor estimated


(8.11E+24 sej/yr, U.S.


1978; Odum 1995) /


(2.06E+08 people; est. population; WRI 1994) / (64.3% population between 15 and 65) / (365 d/yr)


/ (3200 kcal/day metabolism)/ (4186J/kcal)


.25E+07 sej/J


(2.98 hrs/ton) (4.55 tons/ha/yr; avg. harvest, Y2 below) (350 kcal/labor-hr, energy expenditure;


Sundberg and Silversides 1988) (4186 J/kcal)


= 1.99E+07 J/ha/yr (1.25E+07 sej/J)


= 2.49E+14 sej/ha/yr


(2.98 hrs/ton) (4.78 tons/ha


/yr) (350 kcal/labor-hr) (4186 J/kcal)


= 2.09E+07 J/ha/yr


(1.25E+07


= 2.62E+14 sej/ha/yr


(2.98 hrs/ton) (2.29


(1.25E+07


tons/ha/yr) (350 kcal/labor-hr) (4186 J/kcal)


= 1.25E+14


= 1.00E+07 J/ha


sej/ha/yr


(2.98 hrs/ton) (2.48 tons/ha/yr) (350 kcal/labor-hr) (4186 J/kcal)


= 1.08E+07 J/ha/vr


(1.25E+07 sej/J)


= 1.36E+14


i/ha/yr


(2.98 hrs/ton) (2.14 tons/ha/yr) (350 kcal/labor-hr) (4186 J/kcal)


= 9.33E+06 J/ha/yr


(1.25E+07 sej/J)


10. Harvest preparation
1978; Odum 1995)


= 1.17E+14


sej/ha/yr


[ reported same for all forest rotations]:
= 8.00E+12 sej/ha/yr


2.00 $/ha/yr (4.0E+12 sej/$, U.S.


Harvested biomass:


Final harvest:
Thinning yield:
Final harvest:


4.55 dry tons/ha/vyr (4.78E+06 kcal/ton) (4186 Jikcal)


(150.7 tons/ha/rotation)


yrs) =


(279.9 tons/ha/rotation) / (90 yrs)


Total biomass harvested:


(1.67 + 3.11) tons/ha/v


= 9.10E+10 J/ha/yr


1.67 tons/ha/yr


= 3.11 tons/ha/vr
r = 4.78 tons/ha/yr


(4.78E+06 kcal/ton) (4186 J/kcal)


= 9.57E+10 J/ha/yr


Thinning yield:
Final harvest:


(21.1 tons/ha/rotation)
(116.4 tons/ha/rotation)


(60 vrs)


= 0.35 tons/ha/yr
= 1.94 tons/ha/vr


Total biomass harvested: (0.35 + 1.94) tons/ha/yr = 2.29 tons/ha/yr
(4.35E+06 kcal/ton) (4186 J/kcal) = 4.17E+10 J/ha/yr


Thinning yield:
Final harvest:


(47.1 tons/ha/rotation) / (80 yrs)
(151.2 tons/ha/rotation) / (80 yrs)


Total biomass harvested:


(0.59 + 1.89) tons/ha/y


= 0.59 tons/ha/yr
= 1.89 tons/ha/yr
r = 2.48 tons/ha/yr


(4.35E+06 kcal/ton) (4186 J/kcal)


= 4.51E+10 J/ha/yr


Thinning yield:
Final harvest:


(57.2 tons/ha/rotation)


(199.2


Total biomass harvested:


(120 yrs)


tons/ha/rotation) / (120 yrs)


(0.48 + 1.66) tons/ha/yr


= 0.48 tons/ha/yr
= 1.66 tons/ha/yr
= 2.14 tons/ha/vr


(4.35E+06 kcal/ton) (4186 J/kcal)


9E+10 J/ha/yr


Summary of measurements:


Items 1-6 = 1.07E+14 sej/ha/yr


Items 7-10


= 2.85E+14 sej/ha/yr


. ta* *a n t t n 1 4 T/f I a ri r '1


=


___


1~ Alni


/T


; T







Table 5--continued.


= (1.01E+15 sej/ha/yr) / (1.07 + 2.85)E+14 sej/ha/yr


= (1.07E+14 sej/ha/yr) / (6.14E+14 sej/ha/yr) = 0.17


= (1.07 + 2.85)E+14 sej/ha


/yr / (6.14E+14 sej/ha/yr)


= 0.64


Items 1-6


7.07E+13 sej/ha/yr


Items 7-10 = 2.99E+14 sej/halyr


(6.85E+14 sej/ha/yr)
(9.83E+14 sej/ha/yr)


(1.17E+11 J/ha/yr)
(9.57E+10 J/ha/yr)


= 5,863 sej/J
= 10,272 seji


= (6.85E+14


sej/ha/yr)


(7.07E+13 sej/ha/yr)


= 9.68


YR, Y /(F, +F


(9.83E+14 sej/ha/yr) / (7.07 + 2.99)E+14 sej/ha/yr


= 2.66


= (7.07E+14 sej/ha/vr) / (6.14E+14 sej/ha/yr) = 0.12


= (7.07 + 2.99)E+14 sej/ha/yr / (6.14E+14


/ha/yr)


= 0.60


Items 1-6


= 6. 13E+13


j/ha/yr


Items 7-10 = 1.47E+14 sej/ha/yr


(6.75E+14 sej/ha/yr) / (6.86E+10 J/ha/yr)


(8.22E+14


sej/ha/yr) / (4.17E+10 J/ha/yr)


= 9,834 sej/J
= 19,697 sej/J


= (6.75E+14 sej/ha/yr) / (6.13E+13


sej/ha/yr) =


YR, Y /(F, + F,)


= (8.22E+14 sej/ha/yr)


(6.13 + 1.47)E+14 sej/ha/yr


= 3.95


= (6.13E+14 sej/ha/yr)


(6.14E+14 sej/ha/yr) = 0.10


= (6.13 + 1.47)E+14 sej/ha/yr


(6.14E+14 sej/ha/yr)


= 0.34


Items 1-6 =
Items 7-10


= 5.76E+13 sej/ha/yr
= 1.59E+14 sej/ha/y


(6.71E+14 sej/ha/yr) / (6.46E+10 J/ha/yr)


(8.30E+14 sej/ha/yr


/ (4.51E+10 J/ha/yr)


= 10,399 sej/J
= 18,383 sej/J


Y, / F,
Y, / (F,


= (6.71E+14 sej/ha/vr)


(5.76E+13


sej/ha/yr)


(8.30E+14 sej/ha/yr)


(5.76 + 1.59)E+14 sej/ha/vr


= 3.84


= (5.76E+14 sej/ha/yr)


(6.14E+14 sej/ha/yr) = 0.09


+F)/I


= (5.76 + 1.59)E+14 sej/ha/yr


(6.14E+14 sej/ha/yr)


= 0.35


Items 1-6


= 5.20E+13


i/ha/vr


Items 7-10 = 1.38E+14 sej/ha/vr


1 (6.66E+14 sej/ha/yr)


(5.67E+ 10 J/ha/vr)


1,740 sej/J


(8.03E+14 sej/ha/yr) / (3.89E+10 J/ha/yr)


= 20,645 sej/J


YR, Y /F,
YR, Y, / (F|


= (6.66E+14 sej/ha/yr)


= (8.03E+14


(5.20E+13 sej/ha/yr) = 12.81


/ha/vr)


(5.20 + 1.38)E+14


/ha/yr = 4.24


= (5.20E+14 sej/ha/yr)


(6.14E+14 sej/ha/yr) = 0.08


= (5.20 + 1.38)E+14 sej/ha/vr


(6. 14E+14


/ha/yr)


= 0.31


= 2.57


, Y,


YR, Y,/F,


Y2,/(F,


+F,) /I


+Fz) /


+F,)/







forest production under 60, 80 and 120 year rotation schedules.


Solar transformities


for loblolly pine forests (Figures 10a, 10Ob) were lower than for mixed hardwoods

(Figures 10Oc, 10d, and 10e) due to higher annual above ground production rates.

Transformities and emergy yield ratios for loblolly pine forests were comparable to

boreal forests in southern Sweden, but mixed hardwoods had higher emergy yields and

lower investment ratios.

Comparing economic emergy invested per ton harvested wood, mixed

hardwood rotations invest on average 8.9E+13 sej/ton compared with 8.2E+12 sej/ton


for loblolly rotations.


Although the emergy yield ratios are higher for mixed


hardwoods on an annual per hectare basis, loblolly pine forests require lower


investments of economic emergy per unit harvested biomass.


These analyses indicate


that, like the boreal forests of Sweden (Figures 8 and 9), older forests with longer

rotation periods deliver more net emergy than younger stands with higher investments.



Slash Pine Forests of Florida


Managed stands of slash pine in north Florida under 25 year rotation schedules

were evaluated for production and harvest of pulp timber (Table 6). Measurements are


summarized in Figure 11.


A solar transformity for above ground production (ST,)


compared with the other conifer systems evaluated, but the transformity for harvested

biomass (ST2) measured twice that of boreal spruce/pine in Sweden or loblolly pine in


Illinois.


An emergy yield ratio for harvested slash pine (YR2) was 20% lower than for


T( vpar nld Inhlnllv nine (Tahie 5(


fnlv 17


of annual production in slash nine


















Economic
sources


Environ-
mental
sources


Loblolly pine
(30 yr.)


(8.83 tons/ha/yr)


1006


(4.55 tonsiha/yr)


E+12 sej/ha/yr


Above ground
production


Harvested
biomass


Solar transformity


4075 sej/J


11,043


Emergy yield ratio
Emergy investment ratio


Economic
sources


Environ-
mental
sources


Loblolly pine
(90 yr)


(5.83 tons/ha/yr)


(4.78 tons/ha/yr)


E+12 sej/ha/yr


Above ground
production


Harvested
biomass


Solar transformity


Emergy y


10,272


field ratio


Emergy investment ratio


Harvest


Harvest









Economic
sources


Environ-
mental
sources


(60 yr.)


(3,77 tons/halyr)


(2.29 tons/halyr)


E+12 sej/ha/yr


Above ground
production


Harvested
biormass


Solar transformity


9834 sej/J


19,697


Emergy yield ratio
Emergy investment ratio


Economic
sources


Environ-
mental
sources


(80 yr.)


(3.55 tons/ha/yr)


(2.48 tons/halyr)


E+12 sej/ha/yr


Solar transformity
Emergy yield ratio


Above ground
production

10,399 sej/J


Harvested
biomass


18,383


11.65


Emergy investment ratio


Economic
sources


Environ-
mental
sources


Mixed hardwoods
(120 yr.)


(3.12 tons/ha/yr)


.14 tons/ha/yr)


E+12 sej/halyr


Above ground
production


Harvested
biomass


Solar


transformity


11,740


20,645


Emergy yield ratio
Emergy investment ratio


;; m i', 1i


/j^^Xflnti 1 1


Craomo A;r,; ra,-,-,,m^nrtil m;vs^rI hsartlwnni dI'viriilhirml


Harvest


Harvest


Harvest





62

Table 6. Emergy evaluation of slash pine (Pinus elliotti) silvicultural production and


timber extraction under
is summarized in Figure


25 year rotation schedules


in north Florida.


Analysis


Resource
units/ha/vr


(J, g. S)


Solar


emergy
per unita


Solar emergy


(E+12 sej/ha/yr)


Environmental sources:


Sunlight


Rain, transpired
Soil organic matter


7.09E+13
5.09E+10
1.36E+08


18200
74000


926.1


SSilviculture:
4. Phosphorus
5. Human services


50.53


2.0E+10
.60E+12


Above ground production


1.81E+11


055.3


(9.6 tons/ha/yvr)

2 Harvesting:


Diesel fuel


4.45E+09
1.56E+07


Labor


Capital costs


Harvested biomass
(3.6 tons/ha/yr)


47900


1.09E+07
1.60E+12


6.73E+10


213.0
170.5
12.6


1451.4


Summary of measurements:

Solar transformitv:


Above ground production
Harvested biomass


5829
21,543


Emergy yield ratio


Above ground production
Harvested biomass


Emergy investment ratio:


Above ground production
Harvested biomass


Notes.







Table 6--continued.


Environmental sources:


Solar energy


= 7092 MJ/m2/yr (Ewel 1991)


7.09E+13 J/ha/yr


Rain, chemical potential energy


= 1320 mm/yr rainfall (NOAA 1982); 1030 mm/yr actual


evapotranspiration (Cropper and Ewel 1983);
(1.030 m/yr) (1000 kg/m3) (4.94E+3 J/kg) =


(area) (ET) (Gibbs free energy)
5.09E+10 J/ha/yr


= (10,000 m2/ha)


Soil used:


20 g/m2/yr (Dissmeyer


981); (20 g/m2/yr) (1E+4 m2/ha) (3% OM content) (5.4


kcal/g) (4186 J/kcal)


= 1.36E J/ha/yr


Silviculture:


Phosphorus:


5.7 lbs/acre/vr absorbed


- 4.0 lbs/acre/yr returned (Prichett 1981)


= (1.7 lbs


P/acre/yr) (acres/0.4047 ha) (454 g/lb)


1910 g/ha/yr


Human services (Strata 1989):


(S/application)


prescribed burn:
tree removal (undesirables)
timber cruise
tree marking


site prep.
planting
thinning


fertilization


no. appl. /
plantation cycle


16.10


per hectare cost
($/ha/yr)


16.10


141.38
6.10
21.19
228.80
91.11
137.23
88.50


3.54
50.53


1 Above ground production
(1/0.48; 48% C in OM) (


= 461 g-C/m2/yr (Gholtz et a


4.5 kcal/g) (4186 J/kcal)


1991); (461 g-C/m /yr)


= 1.81E+11


1E+4 m2/ha)


J/ha/yr


Harvesting:
6. Fuels used in harvest (Anonymous 1
(road construction and maintenance:


976):


(stump to mill handling; 4 gal/ton, oven dry wt.) +


0.2 gal/ton) + (supervision: 0.15 gal/ton)


= 4.35 gal/ton


(2.86E+8 J/gal, heat content of fuel)


tons/ha/yr; harvest, Y


below)


= 4.45E+9 J/ha/vr


Labor (Anonymous 1976):


(harvest planning and layout; 0.06 labor-hrs/ton, oven dry wt.) +


(road construction and maintenance; 0.06 hrs/ton) + (stump to mill handling; 2.21 hrs/ton)


(equipment maintenance; 0.55 hrs/ton) (supervision; 0.10 hrs/ton)


= 2.98 labor-hrs/ton (3.5


tons/ha/yr; harvest, item Y,) (350 kcal/labor hr energy expenditure; Sundberg and Silversides


1988) (4186 J/kcal)


= 1.56E+7 J/ha/yr


Solar transformity for U.S. labor estimated as:
Odum 1995) / (2.5E+8 people; U.S. population;


(8.61E+24 sej/yr; emergy-use in U.S., 1990;


(WRI 1994)


(64.5% population between


15-60) / (365 d/yr) / (3200 kcal/day, metabolism) / (4186 J/kcal)


= 1.09E+7 sei/J.


Capital depreciation (Anonymous
= 7.90 $/ha/yr


1976):


(2.21 $/ton) (3.57 ton/ha/yr; Y


below)


Harvested biomass:


(73 ft3/acre/yr; Sheffield 1981)


acres


/ha) (0.028 m'/ft')


0.70 ton/m',


* .-- n t nn--. *r. *rI. a I t. -


f *- T I








Table 6--continued.


(2nd estimate):


(14,983 g/m2, tree wood biomass of 27 yr. old plantation: Gholz et al. 1986)


(27 yrs) (1E+6 g/ton) (1E+4 m2/ha) = 5.55 tons/ha/yr (62% sawn timber, pulpwood, sawdust)
3.45 tons/ha/yr, harvest (1.88E+10 J/ton) = 6.48E+10 J/ha/yr


Summary of measurements:


Items


= 936.2E+12


/ha/yr


Items 4+5


= 119.1E+12 sej/ha/yr


Items 6+7+8


= 396.1E+12


/ha/yr


= 1055.IE+12 sej/ha/yr


Solar transformities


= 1451 2E+12 s

S= Y, (sej/ha/yr)


ej/ha/yr


Y, (J/ha/yr):


Above ground production


= (1.055E+15 sej/ha/yr) / (1.81E+1 I J/ha/yr)


= 5829


Harvested biomass


= (1.451E+15


/ha/yr)


(6.73E+10 J/ha/yr)


= 21,563 sej/J


Emergy


field ratio


Above ground production


= (1055E+12 sej/ha/yr)


(119.1E+12 sej/ha/yr)


= 8.86


Harvested biomass


= (1451E+12


/ha/yr) / (119.


+ 396.1)E+12 sej/ha/yr


= 2.82


Emergy investment ratio


= (F,+... F,) / 1:


Above ground production


= (119.1E+12 sej/ha/vr)


(936.2E+12 sei/ha/vr)


= 0.13


Harvested biomass = (119.1 + 396.1)E+12 sej/ha/yr


(936.2E+12 sej/ha/vr)


= 0.55


I+F,+F


... F,):






























Environ-
mental
sources


Slash pine


1055.3


(9.6 tons/ha/yr)


170.5


1451.4


tons/ha/yr)


E+12


Above ground
production


Harve


biomass


Solar transformity
Emergy yield ratio


5829


21,543


Emergy investment ratio


Fio1re 11


Cvctamc diaornm nf9dach ninap Pinus ellinttii) silvicultural production and


Harvest


sej/ha/yr





66

stands is harvested compared with 52% in loblolly and 75% in boreal spruce/pine.


The emergy yield decreases


77% from production of standing crop to harvested timber,


identifying the high cost of timber extraction (F,) in southern pine stands (110.0E+12

sej/ton compared with 86.1E+12 sej/ton for 30 year old stands of loblolly pine).



Secondary Rainforests of Paoua New Guinea


An emergy evaluation of a 20,000 ha lowland rainforest logging operation on


the island of New Britain, Papua New Guinea is given in


Figure


Tabi


A forest-land rotation model (Doherty and Brown


e 7 and diagrammed in

1992) calculated that


cleared forest land would reach a mature steady state in about


tons/ha above ground biomass.


140 years with 380


A solar transformity for above ground biomass


measured higher than other forest biomass evaluations, including old growth

spruce/pine in Sweden and 140 year old temperate mixed hardwoods in Illinois.


Emergy yield of harvested timber (Y,


= 2.27) was lower than other mature forests


studied and comparable with yields from younger stands due in part to a low


percentage (39%) of usable timber extracted from the forest.


The low yield and high


investments (291.8E+12 sej/ton) is notable since there were no silviculture involved.



Emergy Evaluation of Plantation Productivity



Salix Plantations in Southern Sweden


Short-rotation willow (Salix spp.) cultivated on abandoned and marginal







Table


. Emergy evaluation of secondary tropical rainforest above ground biomass
and timber extraction in New Britain, Papua New Guinea?.8 Analysis is
summarized in Figure 12.


Resource
units/ha/yr
(J, g, S)


Solar emergy


emergy
per unit


(E+15


sej/ha/yr)


Environmental sources:


7.77E+12 J


1.82E+04


141.41


Above ground biomass
(380 tons/ha)


7.60E+12 J


141.41


Fuels


Machinery


Other equipment
Road construction


Labor


Miscellaneous costs


4.01E+10 J
1.00E+10 J
1.66E+03 $
1.89E+02 $
4.63E+08 g
6.75E+02 $


1.79E+03


5.30E+04
6.80E+04
2.00E+12
2.00E+12
1.50E+06
4.80E+13
2.00E+12


0.38
0.69
32.41
3.58


Harvested biomass
(148 tons/ha/yr)


2.96E+12 J


98.20


Summary of measurements:

Solar transformity:


Above ground biomass
Harvested biomass


18,533
33,117


Emergy yield ratio:
YR, Harvested biomass


Emergy investment ratio:
IR, Harvested biomass


Notes.
a. Data from from Tickell personal communication (1990) from an evaluation by Doherty and Brown
(1992) unless cited otherwise in footnotes.


Inputs calculated


as available energy are multiplied by solar transformities (sej/J) to obtain solar


emergy; inputs reported


as mass use


sej/g; monetary inputs use sej/$ for regoinal economy and year


of production (Table


unless cited otherwise in footnotes).







Table 7--continued.


Environmental sources = evapo-transpired rain: (3.73 m/yr, rainfall) (60% ET
kg/m3) (4940 J/kg) = 1.11E+11 J/ha/yr (140 years to reach mature steady state
7.77E+12 J/ha


Above ground biomass:


) (10000 m2) (1000
) (est. 50% used) =


380 tons/ha (est. Brown and Lugo 1984); (380 ton/ha) (2.0E10 J/ton)


= 7.60E+12 J/ha


Above ground production:
= 5.84E+11 J/ha/yr


29.2 tons/ha/yr (est. Jordan 1971); (29.2


tons/ha/yr) (2.OE+I0 J/ton)


Fuel used in harvest: 30,000 liters/mo;


= (1.30E+13 J/yr)


(3E+4 liters/mo) (energy content 3.60E+07 J/1) (12 mo/yr)


(324.3 ha/yr harvested) = 4.01E+10 J/ha/yr


Oil, lubricants, etc. (3500 kina/month)


(0.93 k/$)


(0.50 $/liter)


= (7527


1/mo) (energy content,


3.60E+07 J/l)


(12 mo/yr)


= (3.2


5E+12 J/yr)


(324.3 ha/yr harvested)


= 1.002E+10 J/ha/vr


Machinery


(capital outlay, 2.00E+6 kina) (est. lifetime, 4 yrs)


(0.93 kina/$)


= (5.38E+5 $/yr)


(324.3 ha/yr harvested)


= 1.66E+3 $/ha/yr


Other equipment:


70E+5 kina) (est. lifetime, 10 yrs)


(0.93 kina/$)


= (6. 13E+4 $/vr)


(324.3


ha/yr harvested)


= 1.89E+2 $/ha/yr


Road materials:


(gravel; 800 m&/mo) (est. rock density 2.0E+6 g/m3) (12 mo/yr)


= 1.54E+1


/ (324.3 ha/yr harvested)


= 4.63E+8 g/ha/yr


Labor:


nationals, 8000 kina/mo


kina/$)


mo/yr)


= 1.03E+5 $/yr. expatriates,


kina/mo / (0.93 kina/$) (12 mo/yr)


= 1.16E+5 $/yr;


total labor


costs = (2.


19E+5 $/yr)


(324.3


ha/yr harvested)


= 6.75E+2 $/ha/yr


Miscellaneous costs = (45000 kina/mo)


(0.93 kina/$) (12 mo/yr)


= 5.81E+5 $/vr)


(324.3 ha/yr


harvested)


1.79E+3 $/ha/yr


Harvested biomass:


min. 120 m'/ha, max.


250 m3/ha;


185 m3/ha) (0.8 tons/m')


= 148 tons/ha


(2.0E+10 J/tons)


= 2.96E+12 J/ha/yr


Harvested bioma


quality) (0.8


ss for entire operation:


tons/m3


(1500 m'/mo, premium quality + 3500 m'/mo, construction


(12 mo/yr) = 48,000 tons/yr


Land area cut annually


= (48000 tons/yr, harvested)


ton/ha, harvested)


/ (380 ton/ha,


standing crop)


= 38.9%]


(380 tons/ha, standing


= 324.3 ha/yr


Summary of measurements:
I, Environmental sources
LI Environmental sources


used in biomass storage (Q,


used in harvested biomass (Y,)


= 141.41E+15


= (38.9%)


sej/ha


= 55.01E+15 sej/ha/yr


items 1-7 = 43.19E+15


sej/ha/yr


12 + F2 = 98.20E+15 sej/ha/yr
Above ground biomass = (141.4E+1


sej/ha/yr)


(7.60E+12 J/ha/yr)


= 18,533


Harvested biomass = (98.20E+15 sej/ha/yr)


(2.96E+1


J/ha/yr) = 33,117 sej/J


Emergy yield ratio for harvested biomass = (98.20E+1


sej/ha/yr)


(43.19E+15 sej/ha/yr)


= 2.27






















Left in field


Labor


iomass


Environ-
mental
sources


Tropical
rainforest


(148 tons/ha/yr)


E+15


Above ground
biomass


Harvested
biomass


Solar transformity
Emergy yield ratio


18.533


33,117


Emergy investment ratio


T;miro 19


C.+,,a+nmi ,-arnm nf crmnndonr trnniref rainforest above Qround biomass and


Harvest


/halyr







in Table 8; Figure 13).


Energy forestry, as it is known, is management intensive with


approximately 6 harvests obtained during one planting cycle of 24 years.


years on average,


Every 4-5


48 tons/ha above ground biomass is harvested, producing on average


1.5 tons/ha/yr. Plantations typically harvest a greater percentage of annual production


than forests; 95% of salix biomass is removed from the field compared with


biomass production in spruce/pine forests of the same region (Table 4).


75% of


Cultivation


emergy (F,) measured 63.6E+12 sej/ton, almost 8 times the emergy invested in


spruce/pine forests.


Harvest emergy per ton harvested biomass (F,) measured 2.3


times less than that for harvested spruce/pine, illustrating the reduction in harvest


expenditures resulting in intensive high density cultivation.


lower transformity for harvested biomass (ST


This is reflected in a


= 6720 sej/J).


The emergy yield ratio for willow production (YR,


= 1.49) was more than 8


times lower than sprue/pine.


An low emergy yield ratio (YR,


.33) and high


investment ratio (IR, = 3.02) for harvested biomass indicate very little net emergy is

available as a fuel source. Irrigation is often necessary in willow plantations, though


this input was not accounted for in this evaluation.


A previous study of irrigated


agriculture showed large investments of purchased resources from the main economy,


reducing the net emergy yield (Odum et al.


1987).


Fuelwood Plantations in South Florida


Using data from Wang et al. (1981), experimental plantation production of


Eucalyptus spp. and Melaleuca spp.


was evaluated for use as a biomass fuel (Table 9;





71

Table 8. Emergy evaluation of willow (Salix spp.) plantation production and fuelwood


harvest under 4 year rotation schedules


in southern Sweden."a


Analysis is


summarized in Figure 13.


Resource
units/ha/yr
(. g, S)


Solar


emergy
per unit


Solar emergy
flow
(E+12 sej/ha/yr)


Environmental sources:

Silviculture:
4. Willow cuttings0
5a. Nitrogen fertilizer
5b. Potassium fertilizer
5c. Phosphorus fertilizer


Herbicides
Motor fuel


Tractors


Direct labor


10. Indirect services


355.1


6.23E+08
7.33E+04
2.46E+04
7.90E+03
1.2E+07
8.48E+08
1.59E+03


65.97
41.51


6715


4.2E+09
2.0E+09
2.0E+10


307.3
45.2
158.4


66000
47900


6.7E+09
1.53E+12
1.53E+12


101.0


Yi Above ground production
(11.5 tons/ha/yr)

Harvesting:


Motor fuel


12. Tractors, trucks
13. Human services


2.24E+11


2.05E+09
1.53E+03


153.92


47900


6.7E+09
1.53E+12


,1086.7


Harvested biomass
(10.9 tons/ha/yr)


2.13E+1


1431.1


Summary of measurements:

Solar transformity:


Above ground production


Harvested biomass


4850
6720


Emergy yield ratio:
YR, Above ground production


Harvested biomass


Emergy investment ratio:
Wh ~A.*


236.0








Table 8--continued; notes.


Analysis based on an average willow production of 11.5 tons/ha/yr dry matter (29 m3/ha/yr),
harvested every 4-5 years and replanted with willow cuttings on a 24 year rotation (Doherty et al.
1993 using Sennerby-Forssee 1986).

Inputs calculated as available energy are multiplied by solar transformities (sej/J) to obtain solar
emergy; inputs reported as mass use sej/g; monetary inputs use sej/$ for regional economy and year
of production (Table 2 unless cited otherwise in footnotes).

The emergy contributions for willow cuttings were derived from the solar transformity for
harvested willow (ST,) calculated in this table. Environmental contributions (I) and societal
energies (F) for cuttings were separated in spreadsheet iterations and accounted for in net yield and
investment ratios to avoid double counting of inputs.

Environmental inputs: considered the same as those for southern Sweden forests; items 1,2 and 3,
Table 4, plus the environmental input to willow cuttings (item 4) used in first year planting.

Silviculture:


Willow cuttings


(5.75


= (20,000 cuttings/ha planted)


harvests/24 yr rotation)


(60 cuttings/stool)


= 0.28% of total harvested biomass; (0.28)


(20,000 stools/harvest)


tons/ha/24 vrs) =


0.77 tons cuttings; (0.77E+6 g salix cuttings/ha) (1.95E+10 J/t)


(24 yrs/rotation)


= 0.62E+9


J/ha/yr


(Note: use solar transformity for harvested willow, ST,).


Fertilizers:


Nitrogen;


1760 kg/ha/24 yr = 7.33E+4 g/ha/yr


Potassium;


90 kg/ha/24yr


Phoshorus; 190 kg/ha/24yr


= 2.46E+4 g/ha/yr
= 7.92E+3 g/ha/yr


Herbicides; (4 liters/ha/24 yr Roundup + 3 1/hI
= 2.87E+8 J/ha/24 yr rotation = 12E+6 J/ha/yr


i/24 yr Gardoprim) (9800 kcal/liter) (4186 J/kcal)
(Note: the heat of formation of the organic


compounds in the herbicides was estimated using the heat value of petroleum, since herbicides


are oil based derivatives.


The caloric value of the herbicide was converted to a solar emergy


estimate using a solar transformity for refined petroleum products 66,000 sej/J: Odum


. Motor fuels:


(stand establishment, 112 liters + herbicide application, 2 1 + planting, 10 1 +


stand management, 460 1)


= 572 liters/24


= (238


1/ha/yr) (35.6E+6 J/l)


= 8.5E+8 J/ha/yr


Tractors [(given


as %wgt. (g)]


stand mgt., 46.0)/ha/24 yr rotation =
useful life) (10 tons) (1E+6 g/tons)=


(stand establ., 10.0 hrs + hebicide appl., 0.2


57.2 hrs/ha/24 yr
1.59E+3 g/ha/vr


= (2.4 operating hrs/h


+ planting, 1.0 +
La/vr) / (15,000 hrs


Direct labor: [(stand establishment/ha/24 yr rotation; planning, 180 SEK + spraying (before


planting), 94 SEK + plowing,


576 SEK + tilling, 414 SEK + planting, 7960


SEK + spraying


(after planting), 94 SEK) + (stand mgt/ha/24 yr; fertilizer spreading, 258


SEK + herbicide


spraying, 626 SEK + other, 90 SEK)]
SEK/$US, 1988) = 65.97 $/ha/yr


= 10,292 SEK/ha/24 yr rotation


= (429 SEK/ha/vr)


10. Indirect human services: [(stand establ/ha/24 yr; herbicide, before 660 SEK + herbicide, after


2510 QD^V XL Cnl :+as I7 n'knp. fl 1\ tc C cry / -12 QflV\ 4-


71) c9-- <* ^ n ^ A,^


!







Table 8--continued.


. Willow production (annual growth)


= (48 tons/harvest) (5.75


harvests/24 yr)


= (276 tons/ha/24 yr) (1E+6 g/tons) (1.95E+4 J/g) / 24 yrs


= 224E+9 J/ha/yr


Harvesting expenditures:


11. Motor fuel


= (1380 liters/ha/rotation) (35.6E+6 J/liter) / (24 yrs/rotation)


= 2.05E+9 J/ha/24 yr


period


12. Tractors, trucks [(given


as %wgt. (g)]


= (48 tons/harvest) /


tons harvested/hr) (5.75


harvests/rotation) /


24 yrs/rotation)


= (3.83 operating hrs/ha/yr) / (15,000 hrs useful life) (6000


kg avg. wt.)


= 1.53 kg/ha/yr


13. Human servi
yrs/rotation)


(87 SEK/ton, havrest costs


= (30.26 SEK/ha/yr)


(48 tons/harvest) / (5.75


(6.5 SEK/$US, 1988)


harvests/rotation) / (24


= 4.65 $/ha/vr


Willow yield (calculated as


production minus 5% loss)


= (276 tons/ha/24 yr) (0.95) (1.95E+10


J/ton) / (24 yrs)


= 213E+9 J/ha/yr


Summary of measurements:


= 355.14E+12


sej/ha/yr


Items 4+... 10


= 731.6E+12


sej/ha/yr


Items 11+12+13


= 344.4E+12 sej/ha/yr


= 1090E+12 sej/ha/yr


I+F-+F,


Solar transformities


= 1430E+12 sej/ha/yr


(sej/ha/yr) / Yi (J/ha/yr):


Above ground production


= (1.09E+14 sej/ha/yr)


(2.24E+11 J/ha/yr)


= 4850 sej/J


Harvested biomass


= (1.43E+15


sej/ha/yr) / (2.13E+I


J/ha/yr)


= 6720 sej/J


Emergy yield ratio


= Y, / (F,+... Fi):


YR, Above ground production


= (1090E+12 sej/ha/yr)


(731.6E+12 sej/ha/yr)


Harvested biomass


= (1430E+12 sej/ha/yr)


(731.6 +344.4)E+12


sej/ha/yr


Emergy investment ratio


= (F,+... F,) / I:


Above ground production


= (731.6E+12 sej/ha/yr)


(355.1E+12 sej/ha/yr)


Harvested biomass


= (731.16 + 344.4)E+12 sej/ha/yr


(355. I1E+12 sej/ha/yr)


= 3.02




















511.7


Environ-
mental
sources


Salix
Plantation


164.5


1086.7


tons/ha/yr)


10.3


236.0


1431.1


(10.9 tons/ha/yr)


E+12


Above ground
production


sej/ha/yr


Harvested
biomass


Solar transformity
Emergy yield ratio


4850


sej/J


6720 sej/J


Emergy investment ratio


2.05


Harvest


(Fertilizer,
^Herbicide/







Table 9


Emergy evaluation fuelwood plantation production (Eucalyptus spp


Melaleuca spp.) under 5 year rotation schedules in south Florida.


is summarized


a Analysis


n Figure 14.


Resource
units/ha/yr
(J, g, S)


Solar


energy
per unit


Solar emergy


(E+12


sej/ha/yr)


Environmental sources:
1 Evapotranspired rain


.09E+10


18200


926.3


Silviculture:
2 Site preparation,


clearing


Seedling establishment


Fertilization


Irrigation
Labor


Human services


2.64E+09
150.00
1.0E+05
1.24E+09
1.35E+06


35.00


47900
.2E+12


4.8E+09
2.55E+05
1.09E+07
3.2E+12


126.3
480.0
480.0
314.9


112.0


Y, Above ground production
(13.0 tons/ha/yr)

Harvesting:


2.18E+11


2454.2


Diesel fuel
Human services


.29E+09
197.47


47900


3.2E+12


253.5
631.9


Harvested biomass
(12.4 tons/ha/yr)


2.07E+11


3339.6


Summary of measurements:

Solar transformitv:


Above ground production
Harvested biomass


11,270
16,143


Emergy yield ratio:
YR1 Above ground production
YR. Harvested biomass


Emergy investment ratio:
IR, Above ground production
IR. Harvested biomass


__








Table 9--continued.


Inputs calculated as available energy are multiplied by solar transformities (sej/J) to obtain solar
emergy; inputs reported mass use use sej/g; monetary inputs use sej/$ for regional economy and
year of production (Table 2 unless cited otherwise in footnotes).

Environmental inputs:


Evapotranspired rain:


inches/yr; NOAA 1977)


(25.4 mm/in)


= (1321 mm/yr)


(1000


mm/m) (78% ET; est. using Cropper and Ewel 1983) (10,000 m2/ha) (1000 kg/m3) (4.94E+03
J/kg) = 5.09E+10 J/ha/yr

Silviculture inputs:


Site preparation: (disl
bedding, 3.41 gal/ha)
2.64E+09 J/ha/yr


king, 20.00 gal/ha + bulldozing,
= 46.lgal/ha (2.86E+08 J/gal


12.50 gal/ha + rotovating, 10.20 gal/ha +
= 1.32E+10 J/ha / (5 yr-rotation) =


Seedling costs:
Fertilization: I
Irrigation: (0.(


(75
N, 50
)25 m


$/1000 individuals) (1 m2 spacing) (1E+4 m2/ha) / (5 yrs.) = 150
kg/ha/yr + P, 50 kg/ha/yr = (100 kg/ha/yr) (1000 g/kg) = 1.0E+5
/yr) (1E+4 m2/ha) (1000 kg/m3) (4.94E+3 J/kg) = 124E+9 J/ha/vr


- "


S/ha/yr
g/ha/yr


Labor:
J/kcal)


(disking, 2.43 hrs/ha + rotovating, 2.16 hrs/ha)


(6.73E+06 J/ha)


(5yrs)


= 4.59 hrs/ha (350 kcal/hr) (4186


= 1.35E+06 J/ha/yr


Human services: (50 $/ha, planting) /


(5 yrs)


= 10 $/ha/vr +


25 $/ha/yr, weeding


= 35 S/ha/yr


Above ground production:


est. 105% annual harvest [% assumed same as willow (Table 8) and


eucalyptus in Thailand (Table 26)]:


(12.35 tons/ha/yr, harvested;


below) (1.05)


= 13.01


tons/ha/yr (4 kcal/g) (4186 J/kcal)


= 2.18E+11 J/ha/yr


Harvesting inputs:


Fuels:


(chainsaw, 33,000 Btu/ton wood + truck transport fuel, 3


Btu/ton (1055 J/Btu) (12.35


Services: 197.47


Harvested biomass:


ton/ha/yr harvest: Y, below)


$/ha/yr; [mean of will


(5 tons/acre/vyr)


73,000 Btu/ton)


= 5.29E+09


= 406,000


J/halvr


w (Table 8) and eucalyptus (Table


(0.4047 ha/acre)


26) costs]


= 12.35 ton/ha/yr (4 kcal/g) (4186 J/kcal) =


2.07E+11 J/ha/yr

Summary of measurements:


Item 1 = 926.3E+12
Items 2+... 7 = 1527


sej/ha/yr
.9E+12 sej/ha/yr


Items 8+9


= 885.4E+12


/ha/vr


= 2454.20E+12 sej/ha/yr


I+F,+F,


= 3339.6E+12 sej/ha/yr


Solar transformities = Y, (sej/ha/yr) / Y, (J/ha/yr):
ST, Above ground production = (2.45E+15 sej/ha/yr)


(2.18E+11 i/ha/yr)


1,270 sej/J


ST, Harvested biomass


= (3.34E+1


sej/ha/yr)


(2.07E+1


J/ha/yr)


= 16,143 sej/J


Emergy yield
YR,


I ratio


(F,+...


Above ground production = (2454E+12 sej/ha/vr)


Harvested biomass


= (3340E+12 sej/ha/yr)


(1528E+12 sej/ha/yr)


(1528 + 885)E+12 seji/ha/yr


= 1.61
= 1.38


Emergy investment ratio = (F,+... F,) / I:
IR1 Above ground production = (1528E+12 sej/ha/yr)


(926E+12 sej/ha/yr)


= 1.65






















606.3ite prep
\planting

606.3


480.0 /
S314.9 /a
/ 126.7


253.5


631.9


Environ-
mental
sources


926.3


Eucalyptus,
Melaleuca
Plantation


2454.2


(13.0 tons/ha/yr)


3339.6


12.4 tons/ha/yr)


E+12


Above ground
production


Harvested
biomass


Solar transformity
Emergy yield ratio


70 sej/J


16,143


sej/J


rgy investment ratio


Figure 14.


stems


Eucalvotu


diagram of plantation production and fuelwood harvest of


I.


SDD. and Melaleuca son. under


vear rotation schedules in south


Harvest


/ha/yr


J





78

transformities were more than twice that of willow in Sweden (Table 8) but the


emergy yield ratios were comparatively low.


Total economic emergy investments


measured 194.6E+12 sej/ton harvested fuelwood, almost twice that of willow

(98.7E+12 sej/ton).



Siris Plantations of Puerto Rico


Siris (A lbizia lebbek), a fast-growing, deciduous pioneer species, is currently

being grown experimentally in Puerto Rico as a possible means of rehabilitating

degraded lands (Parrotta 1992) and is used widely throughout the world as a fuelwood


source.


It is evaluated for production and possible harvest as a fuelwood source in


Table


10 using unit investments per ton biomass from willow plantations.


Figure


summarizes the emergy calculations.


On a rotation cycle of 11 years, siris produces


an average of about 10.4 tons/ha/yr above ground biomass.


Cultivation and management emergy measured 44.1E+12 sej/ton,


with human


services and direct manual labor accounting for over 60% of the economic sources.

harvesting only branches and stems, about 88% of annual production is removed.

Total economic emergy, 82.0E+12 sej/ton, accounted for 43% of the total emergy-


used.

(YR,2


Emergy yield ratios for plantation biomass (YR, = 3.15) and harvested fuelwood

= 2.32) were higher than values for other plantations. Transformities were lower


for siris than for Eucalyptus and slightly higher than willow.







Table 10.


Emergy evaluation of siris (Albizia lebbek) plantation production and


possible fuelwood harvest under


1 year rotation schedules


in Puerto Rico.a


Analysis


summarized in Figure 1


Resource
units/ha/yr


(J, g, $)


Solar


Solar emergy


energy
per unit


sej/ha/yr)


Environmental sources:


Rain, transpired
Mineral soil


Phosphorus


.05E+10
45000


6800


18200


918.1


.12E+09
.70E+09


Silviculture:
4. Site preparation,


planting


.95E+08


47900


Tractor


. Weeding (manual labor)
. Seedling costs
. Services


Capital expenses


1.19E+07


10.85


139.97
81.14


6.70E+09
4.81E+06
1.64E+12
1.64E+12
1.64E+12


229.6
133.1


Above


ground production


.73E+1 1


1446.8


(10.4 tons/ha/

Harvesting:


10. Fuels
11. Tractor
12. Services


1.63E+09


122.39


Harvested biomass


1.53E+1


47900


6.7E+09
1.64E+12


200.7


1733.5


tons/ha/yr)


Summary of measurements:

Solar transformity:


Above ground production
Harvested biomass


Emergy


8344
1,335


field ratio:


Above ground production
Harvested biomass


Emergy investment ratio:
IR, Above ground production


Note







Table 10--continued; notes.


Since the siris plantation used in this evaluation was only 4.5 years old (Parrotta 1993a), rotation


period was taken


as the lower end of optimal rotation length for similar rain-fed plantations in


India, reported as 11-14 years (Parrotta 1987a).


Biomass accumulation rates are based on 4.5


years


of growth.


Inputs calculated a


s ava


ilable energy are multiplied by solar transformities (sej/J) to obtain solar


emergy; inputs reported mass use use sejlg: monetary inputs use sej/$ for regional economy and
year of production (Table 2 unless cited otherwise in footnotes).

Environmental sources:


Evapotranspired rain
Bislev watershed avg


= 1600 mm/yr (Parrotta 1992), rain; 2.8 mm/day, transpiration (64%)
. (Scatena personal communication): (2.8 mm/day) / (1000 mm/m) (365


days/yr) (1E+4 m2/ha)


1000 kg/m3) (4.94E+03 J/kg)


= 5.05E+10 J/ha/yr


Mineral soil erosion = 3 mm/yr; est. (half Luquillo forest rate):


(3 mm/yr)


(1000 mm/m)


(1E+4 m2/ha)


1.50E+3 g/m3; bulk density)


= 4.50E+04 g/ha/yr


Phosphorus (from weathering and rain):


6.80E+3 g/ha/yr; (Parrotta 1987b)


ST = phosphate formation in Fla. (Odum 1995)

Silviculture (estimates using willow plantation inputs, Table 13 unless otherwise cited):


Fuels:


(112 liters/ha; stand establ.


= 4.34E+09 J/ha/rotation


(11.0 yr-


+ 10 liters/ha; planting =
-rotation) = 3.95E+08 J/ha


(122 1/ha) (3.56E+07 J/liter)


Tractors:


10 hrs/ha; stand establ.


+ 1 hrs/ha; planting


hrs/ha)


/ (15000 hrs; useful


lifetime) (6000 kg; tractor wt) (1000 g/kg)


= 4400 g/ha/rotation


(11.0 yr-rotation)


= 400 g/ha/yr


Weeding (manual labor):


plots were manually weeded every


2 months for 1st year (Parrotta


1993b):


(0.50 hrs)


(10xl0 m plot)


mo.) (1.0OE+4 m2/ha) (12 mos./yr) = 300


hrs/ha/rotation (2500 kcal/day) (24 hrs/day) (4186


J/kcal)


= 1.31E+08 J/ha/rotation


yr-rotation)


= 1.19E+07 J/ha/yr


Seedling


costs:


$/1000 ind.; pri


ce of willow seedlings) (1


7500 ind./ha;


of 2x2m,


lxlm, 0.5x0.5m density plots (Parrotta 1993a)


= 1312.5 $/ha


(11.0 yr-rotation)


$/ha/yr


Services:
price, July


1539.65 $/ha


(11.0 yr-rotation)


= 10.85$/ha/vr


(122 liters fuel/ha: stand establ., planting) (0.2642 gal/I) (1.23 $/gal;
1995) = 39.65 $/ha; (300 hrs/ha; manual labor, item 6) (5.00 $/hr)


(11.0 yr-rotation)


U.S. avg gas
= 1500.00 $/ha.


= 139.97 $/ha/vr


Capital expenses:


$/ha; avg. land price for


Forest (Scatena personal communication):


(2898


areas
$/ha)


surrounding Luquillo Experimental
(28.00 $ / 1000 $ assessed land value;


property tax)


= 81.14 $/ha/vr


i Above ground production:


(46.6 tons/ha above ground biomass (incl. understory) after 4.5


years (Parrotta 1993a);
= (1.73E+11 J/ha/yr


(46.6 tons/ha)


(4.5 yrs) = 10.36 tons/ha/yr (1.67E+10 J/ton)







Table 10--continued.


Harvest (per ton estimates using willow plantation inputs, Table


3 unless otherwise cited):


10. Fuels:
below)


Tractor:


(5 liter/ton) (3.56E+07 J/liter)


1.78E+08 J/ton (9.13 tons/ha/yr; avg. harvest, Y,


= 1.63E+09 J/ha/yr

: (0.33 hrs/ton) (15000 hrs; useful lifetime) (6000 kg; tractor wt.) (1000 g/kg)


= 132 g/ton (9.13 tons/ha/yr; avg. harvest, Y2 below)


= 1206 g/ha/yr


12. Services: (13.40 $/ton) (9.13 tons/ha/yr; avg. harvest, Y2 below)


= 122.39 $/ha/yr


Harvested biomass:


4110 g/m2; branches, stems (w/o leaves,


understory) (Parrotta 1993a);


(4110 g/m2) / (.0OE+6 g/ton) (1.OE+4 m2/ha) = 41.1 tons/ha / (4.5 yr-growth)


(1.67E+10 J/ton)


= 9.13 tons/ha/yr


= 1.53E+11 J/ha/yr


Summary of measurements:


Items 1+2+3
Items 4+... 9


= 9.88E+14 sej/ha/yr
= 4.59E+14 sej/ha/yr


Items 10+... 12 = 2.87E+14 sej/ha/yr
I+F, = 1446.83E+12 sej/ha/yr


I+F,+F,


= 1733.49E+12 sej/ha/yr


Solar transformities


Yi (sej/ha/yr)


, (J/ha/yr):


ST, Above ground production = (1446.83E+12 sej/ha/yr) / (1.73E+11 J/ha/yr)


= 8344 sej/J


ST, Harvested biomass


= (1733.49E+1


sej/ha/yr)


(1.53E+1


J/ha/yr)


11,335 sej/J


Emergy yield ratio


= Y, / (F,+... F,):


Above ground production


Harvested biomass


= (1.73E+15


.45E+15 sej/ha/yr)


(4.59E+14 sej/ha/yr)


sej/ha/yr) / (459 + 287)E+12


sej/ha/yr


= 3.15
= 2.32


Emergy investment ratio


= (F,+... F,) / 1:


IRI Above ground production


= (459E+12


/ha/yr) / (988E+12


IR2 Harvested biomass = (459 + 287)E+12 sej/ha/yr


/ha/yr)


(988E+12 sej/ha/yr)


= 0.46
=0.76




















achin


Plantation


380.5


1446.8


(10.4 tons/ha/yr)


200.7


9.1 tons/halyr)


E+12


Above ground
production


sej/ha/yr


Harvested
biomass


Solar transformity

Emergy yield ratio


8344 sej/J


11,335


sej/J


Emergy


investment


- -1. r t l -


n- U ..l.~\ -IA -^ a --- : i.1


Harvest


'*


(Manual
\weeding


~I I


I


1





83

Emergy Evaluation of Non-market Forest Services



In this section, examples of ecosystem services which currently do not have

identified market values are drawn from emergy evaluations of forest systems in

Puerto Rico.



Carbon Sequestration

Five natural forest ecosystems in Puerto Rico were evaluated for emergy


supporting annual production and stored in biomass (Table 11).


These include four


major forest types in the Luquillo Experimental Forest of eastern Puerto Rico:

montane cloud forests, mid-elevational colorado forests, lowland tabonuco rainforests,

and ubiquitous wet palm forests (Figure 16); and the Guanica tropical dry forest in

southern Puerto Rico.

Montane cloud forests had the lowest annual production and a similarly low


transformity (ST


= 2322 sej/J).


Palm forests, inhabiting wet slopes and high ridges,


had the highest production (Y


= 19.5 tons/ha/yr) but a low transformity (ST


= 2286)


due to high surface water runoff and low plant evapo-transpiration.


rainforest had the largest production transformity (ST4

greatest quantity of emergy in mature biomass (Figure


Lowland tabonuco


= 9000 sej/J) and stored the


Dry forest biomass (Q5


45 tons/ha) and cloud forest biomass represented the lowest emergy storage of Puerto

Rico's forests.

Seauestration of atmospheric carbon ranked from 1.85 Mg-C/ha/vr for cloud








Table


Emergy evaluation of above ground production and biomass storage in five


natural tropical forest ecosystems in Puerto Rico.


Analysis is summarized


in Figure 16.


Resource


Forest type


units


(J/ha/yr)


Solar


emergy
per unita


Solar em


flow
(E+12 sej/ha/yr)


Montane cloud forest


Solar insolation


Wind, kinetic energy
Rain, physical potential


4.90E+13
7.90E+09
3.19E+10


1500
10500


11.9
334.9


Evapotranspiration


Cloud condensation
Direct rainfall


Net primary production


7.90E+08
7.11E+09


8200
8200


129.5


6.20E+10


143.9


Premontane Colorado forest
5. Solar insolation
6. Wind, kinetic energy
7. Rain, physical potential
8. Evapo-transpired rain


5.38E+13
3.95E+09
4.66E+10
4.10E+10


10500
18200


489.3
746.2


2 Net primary production


1.27E+11


746.2


Palm forest


9. Solar insolation
10. Wind, kinetic energy
11. Rain, physical potential
12. Evapo-transpired rain


5.38E+13
3.95E+09
4.22E+10
4.10E+10


10500


443.0
746.2


Net primary production


3.19E+1


746.2


Lowland Tabonuco forest


13. Solar insolation


14. Wind,


kinetic energy


15. Rain, physical potential
16. Evapo-transpired rain


5.84E+13
3.60E+09
2.43E+10
8.69E+10


10500


255.2
1582.4


Net primary production


Guanica dry forest
17. Solar insolation


w 0 r--. a -- -


1.76E+11


7.06E+13
'5 r-'Tr i 1 A


1582.4


10-lOn


AC\







Table 11--continued.


Resource


Forest type


units


Solar


emergy
per unit


Solar emergy
stored
(E+15 sej/ha)


Montane cloud forest


(82.9 tons/ha)


1.38E+12


2322


Premontane Colorado forest


(135.8 tons/ha)


2.27E+12


5864


13.30


Palm forest


(199.1 tons/ha)


Lowland Tabonuco forest


(197.9 tons/ha)


3.31E+12


9000


29.74


Gugnica dry forest
(45.0 tons/ha)


7.52E+11


Notes.


Environmental


sources


are calculated


as available energy and multiplied by solar transformities


(sej/J) to obtain solar emergy.
Solar transformities for forest biomass are from forest production evaluations calculated
footnotes below.

Montane cloud forest:


Solar insolation:


(3210 kcal/m2/d)


IE+4 m2/ha) (4186 J/kcal) (365 day


= 4.9E+13 J/ha/vr


Wind, kinetic energy:


(1000 m, vertical gradient) = 0.000025


km/hr; Weaver et al. 1973) (1000 m/km)


(1.23 kg/m3


air density


(3600
m2/see


sec/hr)


m/s /


,eddy diffusion)


(31536000 sec/yr) (10,000 m2/ha)


2.42E+8 J/ha/yr


2nd est. using data from El Yunque (Scatena personal communication)


= 7.90E+9 J/ha/vr


Geophysical potential energy from falling rain:


[4.34 m/yr runoff, (rain


= 4.5 m): Lugo 1986]


m, elevational change) (10,000 m2/ha) (1000 kg/m3) (9.8 m/s2)


= 3.19E+10 J/ha/yr


4a. Cloud condensation:


[0.45 m/yr (10% of tota


precipitation); Weaver 1972]


= 0.02 m/vr


transpired (10,000 m2/ha) (1000 kg/m3) (4940 J/kg)


= 7.9E+8 J/ha/yr


4b. Chemical potential energy of evapotranspired rain: [0.14 m/yr ET, (rain


= 4.5 m + cloud


condensation); Lugo 1986


, Above ground production [NPPAG


(10,000 m2/ha) (1000 kg/m3) (4940 J/kg)


(Weaver and Murphy 1990):


= 7.11E+9 J/ha/yr


3.7 tons/ha/yr) (1E+6 g/ton)


(4 kesl/o- Odum 19701 (4186 J/kcafl


= 6.2E+10 J/ha/vr


3.33E+12