** -"1 I ^CFW-85-03
ASSESSING WETLAND VALUES IN
LANDSCAPES DOMINATED BY HUMANITY
Mark T. Brown, Ph.D
Center For Wetlands
University of Florida
As the character of the landscape changes through development
actions the values placed on undeveloped lands undergo change as well.
Recent history shows that wetlands once considered worthless are now
considered to have very high value. Changing value systems may be the
result of heightened awareness brought on by scarcity. Basic micro
economic theory has as its foundation the "law" of supply and demand,
where, as the supply of any commodity diminishes, the demand and thus
value increases. With changing values comes the need for strategies to
protect that which is valued and may be threatened. Wetlands are now
preserved and protected in many parts of the country, and new legislation
is being introduced in other areas as wetland values are perceived.
As the first wave of public awareness and resulting protective
strategies begins to subside, a second more clearly defined set of
policies and regulations may be needed to reflect the values of wetland
ecological systems in landscape mosaics that are dominated by humanity.
Strategies for wetlands management may be needed that are based on
maximizing benefit to both nature and society. Wetlands management may
best be thought of, first, as landscape management where the entire
landscape is considered as one system and not dissected into parts for
management by various state and local agencies.
The management of landscapes for the benefit of nature and society
requires that those in management positions approach their task with a
certain amount of creativity and insight. In some areas, control of
landscape development may take the form of fairly strict prescriptive
regulations, while in other areas, control may be more management
oriented, where planners and regulators seek to develop a wholistic
Proceedings of National Wetland Assessment Symposium: 1-17
approach to utilization of the landscape and adopt more performance
oriented regulations (see for instance, Brown and Starnes, 1983).
In either case, management policies might be more clearly defined in
light of much recent scientific research concerning the interrelationships
of the various components of the landscape mosaic. To regulate and manage
for only one component of the landscape is increasingly understood to be
counter productive, and may in the long run result in the mismanagement of
the whole. Just as wildlife management strategies have incorporated the
concept of whole systems management rather than management for single
species, wetland managers might begin to consider the whole landscape,
even if the goal is protection of a single element like wetlands.
Energy Signatures of Landscapes
The landscape is a physical manifestation of inflowing energies of
many types and quantities. The character of the mosaic of ecosystems that
make up any landscape unit is a result of the types and quantities of
driving energy flows that are characteristic of the unit. Sometimes
referred to as its "energy signature", the types and quantities of energy
inflowing drive landscape processes that develop storage of materials and
energy, and ultimately exit the unit either as outflows of energy still
having the potential to do useful work, or as degraded heat, having no
Where the dominant energies are rain and surface waters, the
landscape mosaic is characterized by a physical and biological pattern
that makes maximum use of this driving energy. In high relief landscapes
the patterns of stream and river systems that develop and the
thermodynamic relationships of energy input and work performed by the
stream in organizing and reorganizing itself in response to the energy in
flowing water are well documented. High relief landscapes are
characterized by the absence of wetlands where the dominant form of the
waters energy is due to gravitational potential. However, in lower relief
landscapes where gradients are lower, and water is slower moving, the
landscape response is to organize wetland fringes and floodplains on
rivers and streams to make maximum use of the chemical potential of
In very low relief landscapes, where precipitation does not run off
so easily,-and waters are slow to develop sufficient head, wetlands
dominate the landscape. Viewed from above these lands resemble figure
ground studies of uplands and wetlands, where it is sometimes difficult to
determine which is the figure and which is the ground. The dominant
energy in this case is the chemical potential energy in water. The
resulting landscape pattern is one dominated by "isolated" wetlands (in
some areas these are considered nonjurisdictional wetlands). Without
steep gradients, surface waters with low nutrient and sediment loads
accumulate in low areas developing conditions favorable to the
establishment of wetland vegetation.
Coastal landscapes have energy signatures that are dominated by
physical energies of waves and tides. Where the energies of waves and
tides are high, the coastline is void of wetlands, adapting instead to
these high energy inputs with relatively "barren" beach and dune systems
or rocky shores. Where wave energies are low, in protected bays and
estuaries, vast expanses of salt marsh and mangrove wetlands dominate
utilizing the energy inputs of alternating fresh water inflows and tidal
pulses of salt water.
In all, the character of the landscape mosaic is determined by its
energy signature. In managing any landscape unit, its dominant driving
energies should be considered, and any protection strategy should include
the protection and management of the driving energies as well. Managing
bottomland hardwoods without managing the watershed that collects and
converges waters that drive the system makes little sense in the long run.
Regulations designed to protect coastal wetlands that do not include
regulation of development in surrounding uplands and concern for quality
and quantity of inflowing fresh water and flushing tidal waters do not
effectively protect the resource. Alteration of driving energies
ultimately changes the system that is adapted to them. The question that
must always be considered, is how much change is tolerable?
Energy Diagrams for System Understanding
To assess wetland values and to help with management decisions, a
means of overview is needed. Wetland values and strategies for their
protection need be defined in light of the larger landscape unit. Energy
diagrams like those given in Figure 1 help to better understand a systems
relationships with the larger environment. By showing the driving
energies entering from the left and top, exports leaving the system to the
right, and its internal processes as links between inputs and outputs, the
systems diagram makes explicit relationships of the system under study to
the larger system.
The symbols used in the diagrams of Figure 1 have precise
mathematical meaning (see Odum, 1984), so that a diagram is also a
mathematical model that can be simulated on computer to gain insight into
the behavior of the system. Driving energies or rates of internal
processes may be varied and simulation results then help to explore the
response of the system to change and may lead to better management
As an example, simulation results of the model of cypress wetlands
in Figure 1, are given in the lower half of the figure. Surface water
inflow is programmed to be lower than normal and then higher than normal.
The resulting graphs show the effects of altered surface water inflow on
hydroperiod and taken as an example, could be used to suggest management
alternatives for development of surrounding uplands. In the first case,
surface waters are diverted and the wetland is much dryer than normal,
while in the second case, where runoff from surrounding lands has been
increased, the wetland is much wetter for longer periods of time. Using
models such as this, the effects of development in surrounding areas on
wetland hydroperiod could be determined prior to development and
suggestions might be made that would mitigate any unwanted changes.
Creating "Artificial" Wetlands
In landscapes where development is high, the energy signature is
dominated by energies released by humanity. Surface and ground waters are
altered in both quantity and quality as development interests change
drainage patterns, impervious surfaces increase, and sewage is released to
the environment. The tendency as the percentage of developed land
increases is a gradual drying of the landscape. Waters runoff faster due
in part to increased impervious surfaces and in part to "flood control" *
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Figure 1. A simplified energy systems diagram of the
hydrologic relationships in a cypress wetlanr in Florida. Simulation
results of water level in the wetland when surface inflow is increased and
decreased are given in the lower half of the figure.
conveyance systems. Where ground water levels were high prior to
development, they are lowered to accommodate buildings and roads and to
minimize storm flooding. Increased withdrawals of ground waters for human
consumption help to lower ground waters even further. As a result of
these and other actions, the landscape mosaic of uplands and wetlands is
shifted in favor of uplands.
Other areas of the landscape may periodically have too much water,
as stormwaters are shunted quickly from developed lands. Hydroperiods are
significantly altered in wetlands receiving these runoff waters. High
water times are much higher and of shorter duration and dry times are much
longer. There is a gradual shift in the species composition of these
wetlands as species that are adapted to drought and periodic flood are
favored over species adapted to smoother hydroperiods. In many areas of
the country stormwater detention basins are required of new developments
to counteract the impacts of increased impervious surfaces.
The creation of artificial wetlands may be an important way to begin
a reversal of trends of wetland loss and stormwater management, and add
new vitality to the landscape mosaic. Ongoing research in Florida
particularly regarding the reclamation of phosphate mined lands has shown
that the creation of wetlands is possible (Brown et.al. 1984a, 1984b).
The single most important variables are seed source and hydroperiod. The
creation of wetlands for stormwater management instead of detention basins
void of vegetation has great potential to enhance water quality and
reestablish runoff hydrographs that more resemble redevelopment
Artificial wetlands established for the purposes of recycling
treated sewage effluent is gaining much attention in Florida. Using
wastewaters to create wetlands has the potential of reversing wetland
losses, creating new wildlife habitat, and reestablishing groundwater
levels where over drainage has decreased ecological productivity.
Wetlands and Wastewater
In recent years the use of wetlands for recycle of treated sewage
effluent has gained much attention, and much research throughout the
country has been conducted to determine feasibility (a bibliography of
______________________________________________________________. ______ i~~
relevant literature is given at the conclusion of this paper). While
there is still much research needed, the general conclusion of research to
date is that wetland systems are well adapted to the role as long as
discharge rates do not exceed capacity of wetland to "treat" wastewaters.
Some researchers have likened the role of wetlands in sewage treatment to
"low energy tertiary treatment facilities".
Much of the controversy over the effectiveness of wetland treatment
systems results from the vast quantities of sewage that are now released
from regional treatment plants. Sizes of treatment plants have risen
dramatically in recent years, so that it is nothing to see 20 -30 MGD
facilities. It is difficult to locate wetland systems capable of
assimilating such large flows. The trend for ever larger treatment
facilities is probably not compatible with wetland recycle of sewage
wastes in many developed regions where large wetland systems are scarce.
Much research is needed to develop smaller scale technology for waste
treatment that has the same treatment efficiencies as the large regional
plants, but at a scale that is more appropriate to the scale of the
Simulation models like that given in Figure 2 are useful in
determining assimilative capacity of wetland systems, and the quantity and
quality of effluent from the wetland. The model is simulated on micro
computer with resulting output like the graphs given in Figure 2 that show
the concentrations of various species of nitrogen and total phosphorus.
Necessary input variables include the quantity and quality of monthly
rainfall, runoff into the wetland, and sewage effluent, as well as the
type and size of wetland. The first graph shows the normal concentrations
of nitrogen and phosphorus in a cypress wetland in central Florida with no
sewage discharge. The second graph shows the concentrations through the
year with-a discharge rate of 2" per week.
Simulation models of the nutrient dynamics within wetland systems
can be utilized by governmental agencies and utilities for planning
purposes to determine options available for the disposal of wastewaters
within the context of anticipated growth and the needs for additional
Coupling Humanity and Nature
To minimize negative impacts, management of the landscape mosaic
might take the form of coupling humanity and nature in a partnership
relationship where the landscape is considered as a whole system and
patterns that include humanity are designed into the mosaic instead of
replacing the mosaic. In this way wetlands and development are not
necessarily at odds with each other, but ways are sought to enhance both
through positive interactions.
The coupling of humanity and nature in the landscape can take
advantage of two values attributed to wetlands that are well known: water
quality enhancement and water storage. Research into both functions
continues; however, while the final word on effectiveness of particular
wetland types for storage and removal efficiencies is still out, the
general pattern is well documented (for a summary of research over the
past 10 years, see Chan et.al., 1982 and Kobriger et.al., 1983). Wetlands
are effective at removing nutrient and heavy metal concentrations from
surface waters and act as filters where waters percolate through peat
layers into ground waters. When not overloaded, wetlands can store storm
waters and act as buffers against damaging flood surges. However to act
in this capacity, they must be coupled to developed lands and not
"protected" to such an extent as to preclude their use. This may require
alternate approach to wetlands protection and management.
Through creative actions of altering drainage patterns slightly, and
creating "artificial" wetlands as detention basins, the developed
landscape can capitalize on existing wetlands, and add to the mosaic by
developing new ones. Shown in Figure 3 is a hypothetical landscape where
development utilizes existing wetlands for storm water storage by reducing
area of land that contributes surface waters reflecting the increased
runoff from impervious surfaces. Vegetated swales and wetland detention
basins are designed into the development pattern to take advantage of the
filtering actions of vegetation and soils.
Sound management of the landscape that includes humanity suggests
that wetland capacity to enhance water quality be incorporated in
management alternatives as a means to protect wetlands and overall
landscape values. Increased pressures for the conversion of wetlands to
/ | \ A X o Property line
-: Wetland Detention Pond
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Florida that utilizes existingnds and creates artificial wetland
for stormwater management. Size of drainage are for existing wetland is
decrWetlaand Detention Pondadsa
o r e s into egetated stormwater Swales
*to Ephemeral drreams
Figure 3. Development plan for a hypothetical landscape in
Florida that utilizes existing wetlands and creates "artificial" wetlands
for stormwater management. Size of drainage are for existing wetland is
decreased and wetland detention basins and vegetated swales are designed
to reroute stormwaters into an engineered stormwater system before release
to the natural drainage pattern.
developed lands, and alterations of surface and ground water patterns have
resulted in loss of viable wetlands. A trend that may be reversed if
wetlands are given new values through their utilization as low energy
wastewater recycle units. Given in Figure 4 are two alternatives for
wastewater recycle through wetlands. In the top of Figure 4 natural
wetlands are utilized and benefits to society include greater wood
production and recycle of water through local groundwaters. In the lower
diagram of Figure 4, an artificial wetland is shown. The 1200 acre site
has a total of 986 acres of herbacious and forested wetlands designed to
recycle 16MGD of wastewater.
Managing Landscapes For Nature and Society
The landscape mosaic of uplands and wetlands and developed lands and
natural lands will continue to undergo change as humanity continues its
rush into the future. Increasing pressure will be placed upon the land
for production of food, fiber, and mineral resources. Whether energy
sources to society increase or diminish, the demands on the environment
for production on the one hand and assimilation of wastes on the other,
will increase. The need for management strategies that recognize the
realities of changing value systems as a result of changing needs of
society is great and can either follow change or initiate change depending
on the insight of those in management positions. What is needed is
strong, creative leadership on the part of landscape managers to help
humanity fit into the landscape rather than develop it in spite of its
many "limitations". Policies and regulations are needed that are based on
a whole systems approach and that capitalize on values of landscape
components when they are considered as one system.
That wetlands are valuable, there is no doubt, but the very same
attributes that are touted as reasons for their protection are then in
many cases not recognized. Wetlands can enhance water quality and help to
minimize destructive storm surges if allowed to act in these capacities.
The protection of wetland systems without an overview that sees why the
protection is necessary in the first place exacerbate the problem. The
problem is the continued decline of environmental quality as humanity
demands more and more from nature; and the solution is look afresh at the
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Fi ure 4. Alternatives for wastewater through wetland
systems. By utilizing natural wetlands, benefits to society include
greater wood production and reycle ofwater through local groundwaters
-Wharton et.a' l-. 1979. Design for "artificial" wetland in lower half has
great potential for increasing reclamation of drained wetlands, and
increasing wildlife values.
landscape, realize that one cannot take one component out of a system and
protect it-at all costs without sacrificing other components as a result.
Wetland managers need to consider themselves managers of complete
landscapes, of which wetlands are an integral part, and realize that great
potential exists for the effective utilization, creation, and management
of wetland ecological systems as part of an integrated landscape mosaic.
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