• TABLE OF CONTENTS
HIDE
 Cover
 Title Page
 Citation
 Table of Contents
 List of Figures
 Acknowledgement
 Introduction
 What is sucess?
 Site selection
 Site surveys
 Factors influencing planting...
 Monitoring
 Concluding remarks
 Literature cited
 Appendix A: Florida Keys site...
 Appendix B: Atlantic Coast site...
 Appendix C: Gulf Coast site...
 Appendix D: Tables






Group Title: Technical paper - Florida Sea Grant College ; no. 60
Title: An Evaluation of historical attempts to establish emergent vegetation in marine wetlands in Florida
CITATION PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00076610/00001
 Material Information
Title: An Evaluation of historical attempts to establish emergent vegetation in marine wetlands in Florida
Series Title: Florida Sea Grant College publication
Physical Description: 1 v. (various pagings) : ill., maps ; 28 cm.
Language: English
Creator: Crewz, David W
Lewis, Roy R., 1944-
Publisher: Florida Sea Grant College Program
Place of Publication: Gainesville Fla
Publication Date: 1991
 Subjects
Subject: Coastal zone management -- Florida   ( lcsh )
Revegetation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: David W. Crewz, Roy R. Lewis III.
General Note: "Grant no.: NA86AA-D-SG068, Project No.: R/C-E-24."
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00076610
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 28013140

Table of Contents
    Cover
        Cover
    Title Page
        Title Page
    Citation
        Unnumbered ( 3 )
    Table of Contents
        Table of Contents
    List of Figures
        List of Figures
    Acknowledgement
        Acknowledgement
    Introduction
        Page 1
        Page 2
    What is sucess?
        Page 2
        Page 3
    Site selection
        Page 3
        Page 4
        Page 5
        Page 6
    Site surveys
        Page 7
        Page 8
        Page 6
        Page 9
    Factors influencing planting success
        Page 10
        Page 11
        Page 9
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Slope and drainage
            Page 18
            Page 19
            Page 20
            Page 21
            Page 22
            Page 23
            Page 24
            Page 17
            Page 25
        Substrate
            Page 26
            Page 27
            Page 28
            Page 29
            Page 30
            Page 31
            Page 32
        Planting rationale
            Page 33
            Page 34
            Page 35
            Page 36
            Page 37
            Page 32
            Page 38
            Page 39
            Page 40
            Page 41
            Page 42
            Page 43
        Site design
            Page 44
            Page 45
            Page 46
            Page 47
            Page 48
        Human intrusion
            Page 49
            Page 50
        Plant quality
            Page 51
            Page 52
            Page 53
        Monitoring
            Page 54
            Page 55
            Page 56
            Page 57
            Page 58
            Page 59
            Page 60
            Page 61
            Page 62
            Page 63
            Page 64
    Monitoring
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 64
    Concluding remarks
        Page 71
        Page 70
    Literature cited
        Page 72
        Page 73
        Page 74
        Page 75
        Page 76
    Appendix A: Florida Keys site descriptions
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Appendix B: Atlantic Coast site descriptions
        1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
    Appendix C: Gulf Coast site descriptions
        1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Appendix D: Tables
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
Full Text
/o/
F 53L


Technical Paper No. 60





An Evaluation of Historical Attempts
to Establish Emergent Vegetation
in Marine Wetlands in Florida


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COLLOEGPR
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David W. Crewz

nra R~c.Lewis III
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Florida Sea Grant College Publication


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AN EVALUATION OF HISTORICAL ATTEMPTS TO ESTABLISH
EMERGENT VEGETATION IN MARINE WETLANDS IN FLORIDA









David W. Crewz
Florida Department of Natural Resources
Florida Marine Research Institute
100 Eighth Avenue, S. E.
St. Petersburg, Florida 33701-5095


Roy R. Lewis III
Lewis Environmental Services, Inc.
P. 0. Box 20005
Tampa, Florida 33622-0005







Grant No.: NA86AA-D-SG068
Project No.: R/C-E-24







TECHNICAL PAPER NO. 60
Florida Sea Grant College

1991


$4.00














Cover photographs: Archie Creek saltmarsh creation at
Gardinier, Inc. June 1978 scrapedown of uplands
and December 1980 marsh aspect. Photographs by
R. R. Lewis, III.















To obtain this publication, write to:

Sea Grant Extension Program
Building 803
University of Florida
Gainesville, FL 32611















Cite as: Crewz, D. W. and R. R. Lewis III. 1991. An
evaluation of historical attempts to establish
emergent vegetation in marine wetlands in
Florida. Florida Sea Grant Technical Paper TP
60. Florida Sea Grant College, University
of Florida. Gainesville, FL.















Table of Contents


List of Figures.................................... ii
Acknowledgements.................................. iii
Introduction...................................... 1
What Is Success?................................... 2
Site Selection..................................... 3
Site Surveys ....................................... 6
Factors Influencing Planting Success................ 9
1) Elevation.......................... ....... 9
2) Slope and Drainage........................ 17
3) Substrate................. ................. 26
4) Planting Rationale.......................... 32
Mangroves................................ 33
Smooth Cordgrass......................... 38
Other Species............................ 41
Density.............................. .... 41
5) Site Design................................ 44
6) Human Intrusion............................. 49
7) Plant Quality.............................. 51
8) Monitoring... ............................. 54
Summary ............................................. 64
Concluding Remarks................................. 70
Literature Cited................................... 72
APPENDIX A: Florida Keys Site Descriptions
APPENDIX B: Atlantic Coast Site Descriptions
APPENDIX C: Gulf Coast Site Descriptions
APPENDIX D: Tables











List of Figures


Figure 1. Site locations............................ 5

Figure 2. Standard sampling methodology............ 7

Figure 3. Generalized locations of common
intertidal plant species in mud
substrates of peninsular Florida......... 13

Figure 4. Tidal types and ranges in Florida........ 15

Figure 5. Movement of red mangrove, as it matures,
into deeper water that is inappropriate
for seedling colonization................. 18

Figure 6. Effect of slope on the extent of
intertidal vegetation along marine
shorelines............................... 19

Figure 7. Projected effect of slope at marine
wetlands margins on extent of vegetation
as sea level rises....................... 23

Figure 8. Exotic nuisance-species invasion of marine
wetlands margins as influenced by the
interaction of slope and disturbance..... 25

Figure 9. Observed responses of planted red
mangrove seedlings in hard (limerock)
and soft (marl mud) substrates
in the Florida Keys...................... 27

Figure 10. Fruiting propagulee) characteristics
of Florida mangrove species.............. 37

Figure 11. Smooth cordgrass vegetative and seed-
production characteristics............... 39

Figure 12. Suggested schedule for monitoring a
smooth cordgrass marsh-creation project.. 62

Figure 13. Characteristics of a hypothetical
unsuccessful saltmarsh creation project.. 65

Figure 14. Characteristics of a hypothetical
successful saltmarsh creation project.... 66














Acknowledgements


This publication is the result of the unselfish
contributions of many individuals. We thank all those
who took the time to fill out site-location question-
naires.
Many government-agency personnel spent consid-
erable time and effort providing site histories.
Special recognition is due personnel of the U.S. Army
Corps of Engineers, especially Curtis Kruer (Florida
Keys), Sharinda Bohall (Fort Myers), Irene Sadowski
(Merritt Island), and Steven Calvarese (Jacksonville),
who helped identify potential study sites. Liberta
Poolt (FDNR, Indian River Lagoon) and Belinda Perry
(Sarasota County Natural Resources Department) provided
valuable assistance, as well.
Robert Whitman, Gene Bauer, Rich Appechello, Pete
Bottone, Beverly Campbell, Rob Mattson, Mike Gallagher,
and Jeffrey Churchill assisted with fieldwork. Artwork
was created by David Crewz, Robert Whitman, and Melanie
Trexler.
Extensive and helpful review comments were made by
Dr. Karen Steidinger, Beverly Roberts, Judy Leiby, Dr.
Carmelo Tomas, Frank Courtney, and Sally Treat. Linda
Boyette, Judy Grimshaw, Karen Murburg, Debra Sobers,
and Darlyn Stockfisch helped with document preparation.
Funding for this project was provided by Florida
Sea Grant and Florida Department of Natural Resources.


iii










Introduction


Since 1969, many sites in Florida have been planted
with emergent species in an effort to create, restore,
or enhance marine wetlands.' Emphasis in marine
wetlands creation has focused predominantly on salt-
marsh and mangrove systems because these wetlands were
more frequently damaged in the rush to develop desir-
able waterfront locations with aesthetic exposures.
Different approaches have been employed in attempts to
create saltmarsh and mangrove wetlands, but how well
these efforts have satisfied objectives for vegetation
cover and site quality is mostly unknown.
Federal, state, and local regulatory agencies that
review permits have a continuing need to assess whether
techniques used in past marine wetlands creation pro-
jects fulfilled objectives, and if not, what could be
done differently. In general, agencies have not had
the personnel to inspect sites adequately, to synthe-
size data necessary for evaluating the success of
wetlands creation projects, to document site short-
comings, or to prepare the information for public
distribution. In response to this need for infor-
mation, Mote Marine Laboratory (MML) and the Florida
Department of Natural Resources (FDNR) submitted a
joint proposal to the Florida Sea Grant Program to
evaluate past techniques used in creating marine
wetlands with emergent plant species. Our original
objectives were to compile-a database of past marine
wetlands projects and, with regard to elevation and
plant-cover interactions, to survey sites selected
randomly from the database. In addition to physical


'For convenience, the terms "restore," "mitigate," and
"enhance" are included under the term "create" in the
remainder of this paper, except where delineation is
needed.







Crewz and Lewis. 1991 Paae 2


aspects, we considered related regulatory and economic
policies that affected site quality. The ultimate
objective of the study was to provide guidelines that
would increase the "success" rate of marine wetlands
creation projects where emergent vegetation is planted.


What is Success?

Early wetlands creation efforts were often deemed
successful as long as the site appeared "green and
growing," regardless of which species were present.
Recent governmental regulations have specified more
quantitative definitions of success, thus fostering
attempts to develop indices that could be used to
describe sites more precisely (e.g., Adamus and
Stockwell, 1983). We interpret "success" in our report
to mean the survival and "acceptable" growth of the
installed plants (if plants were used) of each species,
thereby apparently producing biologically productive
wetlands of the proposed type. We do not wish to
imply, however, that a direct relationship exists
between the presence or robustness of vegetation and
habitat quality. Environmental conditions that improve
habitat qualities for one group of organisms in the
short term may be detrimental to other groups of
organisms or to that same group in the long term.
Determining what constitutes a "good" habitat is a
refractory problem that confounds evaluating functional
equivalency for created and natural habitats.
Because habitat creation goals were not specified
for most sites in our study, our evaluations may differ
from the evaluations of others. For instance, although
the primary site-construction goals of improving water
movement or of creating open areas for bird use may
have been achieved, we might consider the site to be


Crewz and Lewis. 1991


Paep 2







Crewz and Lewis. 1991 Paae 2


aspects, we considered related regulatory and economic
policies that affected site quality. The ultimate
objective of the study was to provide guidelines that
would increase the "success" rate of marine wetlands
creation projects where emergent vegetation is planted.


What is Success?

Early wetlands creation efforts were often deemed
successful as long as the site appeared "green and
growing," regardless of which species were present.
Recent governmental regulations have specified more
quantitative definitions of success, thus fostering
attempts to develop indices that could be used to
describe sites more precisely (e.g., Adamus and
Stockwell, 1983). We interpret "success" in our report
to mean the survival and "acceptable" growth of the
installed plants (if plants were used) of each species,
thereby apparently producing biologically productive
wetlands of the proposed type. We do not wish to
imply, however, that a direct relationship exists
between the presence or robustness of vegetation and
habitat quality. Environmental conditions that improve
habitat qualities for one group of organisms in the
short term may be detrimental to other groups of
organisms or to that same group in the long term.
Determining what constitutes a "good" habitat is a
refractory problem that confounds evaluating functional
equivalency for created and natural habitats.
Because habitat creation goals were not specified
for most sites in our study, our evaluations may differ
from the evaluations of others. For instance, although
the primary site-construction goals of improving water
movement or of creating open areas for bird use may
have been achieved, we might consider the site to be


Crewz and Lewis. 1991


Paep 2







Crewz and Lewis. 1991 Paae 3


substandard in terms of vegetation cover. In this
survey, we are evaluating only the potential for the
establishment and subsequent spread of vegetation over
the short term, not the complex issues of habitat
quality and functional equivalency relative to natural
marine wetlands. Data of sufficient accuracy and
breadth are lacking concerning functional equivalency
of man-made and natural marine wetlands; proper collec-
tion and synthesis of these data will take decades.


Site Selection

Originally, site selection was to be based on strati-
fied, random samples from an FDNR database of all
emergent marine wetlands creation sites in Florida.
The planned database was to be created from information
obtained from government agency files (e.g., Florida
Department of Transportation [FDOT], U. S. Army Corps
of Engineers [ACOE]) and from private companies
involved in marine wetlands modifications. Only 15
percent of the 600+ requests-for-information mailed to
potential contributors were returned, and of these,
only 56 percent (8 percent of total) contained site
information relevant to the scope of this project.
Subsequent interviews and site visits indicated much of
the information regarding original site construction
was of questionable accuracy. When more than one
source for a particular site was consulted, information
concerning certain variables, such as planting density,
often conflicted. Because of incomplete and inaccurate
record keeping, especially for earlier projects, much
of the site information appeared to be based on hearsay
or was altogether lacking. Also, private companies
were often wary of contributing project information,
claiming that violations of client privacy or increased


Crewz and Lewis. 1991


Pace 3







Crewz and Lewis. 1991 Paae 3


substandard in terms of vegetation cover. In this
survey, we are evaluating only the potential for the
establishment and subsequent spread of vegetation over
the short term, not the complex issues of habitat
quality and functional equivalency relative to natural
marine wetlands. Data of sufficient accuracy and
breadth are lacking concerning functional equivalency
of man-made and natural marine wetlands; proper collec-
tion and synthesis of these data will take decades.


Site Selection

Originally, site selection was to be based on strati-
fied, random samples from an FDNR database of all
emergent marine wetlands creation sites in Florida.
The planned database was to be created from information
obtained from government agency files (e.g., Florida
Department of Transportation [FDOT], U. S. Army Corps
of Engineers [ACOE]) and from private companies
involved in marine wetlands modifications. Only 15
percent of the 600+ requests-for-information mailed to
potential contributors were returned, and of these,
only 56 percent (8 percent of total) contained site
information relevant to the scope of this project.
Subsequent interviews and site visits indicated much of
the information regarding original site construction
was of questionable accuracy. When more than one
source for a particular site was consulted, information
concerning certain variables, such as planting density,
often conflicted. Because of incomplete and inaccurate
record keeping, especially for earlier projects, much
of the site information appeared to be based on hearsay
or was altogether lacking. Also, private companies
were often wary of contributing project information,
claiming that violations of client privacy or increased


Crewz and Lewis. 1991


Pace 3







wPaae 4


competition would result from disclosure of techniques.
The difficulties of establishing the database forced us
to abandon the original site-selection procedure and to
use a subjective approach. We chose the sites to be
surveyed using several criteria: accessibility (physi-
cal and legal), accuracy of site establishment infor-
mation, species planted (grasses vs. mangroves vs.
other approaches), and geographic location.
The majority of the sites (18) were on the Gulf
coast (Figure 1), and most were fairly well known to
one of the investigators (R.R.L.). Six sites were on
the Atlantic coast, and eight sites were in the Florida
Keys. Acceptable sites in north Florida could not be
located. Twenty-nine sites in peninsular Florida were
sampled; some sites were separated into the main
planted wetlands and fringe/adjacent plantings that
involved different techniques (e.g., see Connie Mack
Island, Connie Mack Island Fringe; APPENDIX C). A
natural saltmarsh adjacent to the Gardinier, Inc.
manmade saltmarsh was sampled because of its apparent
similarity to the mitigation marsh. All other sites
differed substantially from adjacent wetlands in
structure or species composition.
A total of 33 areas were evaluated, encompassing a
broad range of substrates, time since construction,
tidal influences, geographic locations, and planting
techniques. Because of yearly environmental varia-
bility, young site ages (1 to 8 years), and the single
site-evaluation visit in this survey, our observations
are somewhat anecdotal. Proper evaluation of wetlands
creation success requires monitoring a range of varia-
bles until the site reaches maturity (see Monitoring
section). The sites in our study provide a cross-
section of projects concerning marine wetlands
creation in Florida and should suffice as preliminary


CrewZ and Lewis 1991


Page 4

















HARBOUR ISLAND (3)
BAYPORT (5)
FM-92 RADIO TOWER \ COSTA DEL SOL
LAS FONTANAS- ~- FOUNTAIN COVE
FEATHER COVE MELBOURNE HARBOUR, LTD.
FEATHER SOUND (2)- -- SEAGROVE
GANDY BRIDGE BOAT RAMP -CAMPEAU CORPORATION
SUNKEN ISLAND/ BELLA VISTA, INC.
GARDINIER, INC. (2)
CONNIE MACK ISLAND


FLORIDA KEYS LAND TRUST, INC. -
CORAL SHORES ESTATES
LOGGERHEAD LANE-
CROSS STREET-----S


--FLORIDA KEYS
AQUEDUCT AUTHORITY
-SEXTON COVE
s--ROCK HARBOR
\-HAMMER POINT


FIGURE 1. SITE LOCATIONS.







Crewz and Lewis, 1991 Page 6




indicators of major problem areas within this field.
The 33 sites surveyed in this study are described
alphabetically within three geographic regions: the
Florida Keys, the Atlantic coast, and the Gulf coast
(APPENDIXES A-C, respectively).. Most of the site-
history descriptions were based on scanty and sometimes
contradictory information obtained from a number of
sources. At times, this resulted in somewhat incom-
plete site descriptions and in permit numbers that may
be inconsistent with other records.
Gulf coast sites were sampled from late February
to April 1986, and Atlantic coast and Florida Keys
sites were sampled in July and August 1986. The age of
each site represents the time between construction and
the sampling dates. Ages ranged from less than one
year to over eight years; most sites were two to four
years old.


Site Surveys

Each site (Figure 2) was sampled by establishing
transects perpendicular to the long axis of the site so
that the transects traversed the principal elevation
gradient. At larger sites, the first transect was
placed at one end of the site, and subsequent transects
were established approximately 25 m apart. This
sampling approach required adjustments to account for
differences in size and shape of each site.
Along each transect, we established a number of
2-m x 4-m plots (8 m2) at interplot distances of 10-15
m. Plots were consequently located semirandomly,
irrespective of vegetated areas (haphazard sampling).
Vegetation in each 8-m2 plot was sampled within three
strata: trees were woody plants over 2.0 m tall,
saplings and shrubs were woody plants between 0.3 and


I




















TRANSECT I





2-m x 4-m PL(


(2) I-m x I-m QUADRATS


FIGURE 2. STANDARD SAMPLING METHODOLOGY,







Crewz -n-- -r- f Dq -l- a 0


2.0 m tall, and herbaceous vegetation was woody plants
less than 0.3 m tall and nonwoody plants. Herbaceous
vegetation was estimated from two 1-m x 1-m quadrats
nested within opposite corners of the 8-m2 plot, and
trees and saplings were estimated in the entire 8-m2
plot. Vegetational composition was measured as per-
centage cover and density of "individuals" (if appro-
priate) by species within each stratum. Tables 1 3
(APPENDIX D) contain summaries of vegetational cover by
geographic region, and Table 4 (APPENDIX D) specifi-
cally summarizes vegetative parameters for smooth
cordgrass (Spartina alterniflora Loisel.).
The 58 plant species encountered in the sample
plots in this survey are listed in Table 5 (APPENDIX
D). Vouchers for many of the plant species have been
deposited in the University of South Florida Herbarium
(USF), Tampa, Florida; other vouchers are held at the
Florida Marine Research Institute Herbarium (STPE), St.
Petersburg, Florida.
Elevations were taken in the center of each 1-m2
quadrat, at the apparent lowest point along each
transect, at the upper and lower extremes of vege-
tation, and in the channels leading into the sites.
Where adjacent, undisturbed wetlands vegetation
occurred, elevations were determined for these areas as
a reference. Site elevations were referenced to the
National Geodetic Vertical Datum (NGVD) from existing,
local benchmarks, when they were available. Table 6
(APPENDIX D) provides a summary of elevation ranges for
the sites by geographic region.
Statistical Treatment Commonly used statistical
procedures parametricc and nonparametric) would not be
appropriate for analyzing the data obtained in this
survey. Most of the data tested non-normal and had
very large variances. To avoid the inevitable misin-


I r


Crewz wnr3 T.PTITiC 1C)CI1


P-i, 0







Crewz and Lewis, 1991 Page 6




indicators of major problem areas within this field.
The 33 sites surveyed in this study are described
alphabetically within three geographic regions: the
Florida Keys, the Atlantic coast, and the Gulf coast
(APPENDIXES A-C, respectively).. Most of the site-
history descriptions were based on scanty and sometimes
contradictory information obtained from a number of
sources. At times, this resulted in somewhat incom-
plete site descriptions and in permit numbers that may
be inconsistent with other records.
Gulf coast sites were sampled from late February
to April 1986, and Atlantic coast and Florida Keys
sites were sampled in July and August 1986. The age of
each site represents the time between construction and
the sampling dates. Ages ranged from less than one
year to over eight years; most sites were two to four
years old.


Site Surveys

Each site (Figure 2) was sampled by establishing
transects perpendicular to the long axis of the site so
that the transects traversed the principal elevation
gradient. At larger sites, the first transect was
placed at one end of the site, and subsequent transects
were established approximately 25 m apart. This
sampling approach required adjustments to account for
differences in size and shape of each site.
Along each transect, we established a number of
2-m x 4-m plots (8 m2) at interplot distances of 10-15
m. Plots were consequently located semirandomly,
irrespective of vegetated areas (haphazard sampling).
Vegetation in each 8-m2 plot was sampled within three
strata: trees were woody plants over 2.0 m tall,
saplings and shrubs were woody plants between 0.3 and


I







Cewz and Lew..s 1991r...


terpretations from using inappropriate statistical
analyses, we discuss the data (average values, ranges,
etc.) in subjective terms and present it in tabular
form (see APPENDIX D).


Factors Influencing Planting Success

Site failures can be attributed to four general
shortcomings: 1) inferior designs and planning, 2)
inferior construction and planting techniques, 3) poor
monitoring methodology and remedial actions, and 4)
insufficient regulatory review. The first two short-
comings influenced many physical factors that had
immediate effects on vegetation coverage. The physical
factors that influenced vegetation establishment at
these study sites can be separated artificially into
seven categories: elevation, slope and drainage,
substrate, planting rationale, site design, human
intrusion, and plant quality. Separating these factors
into discrete categories is artificial in that inter-
actions among them are complex, and altering values in
one category usually alters values in the others.
These seven categories are discussed in the following
sections in order of their decreasing occurrence among
the sites in this investigation. Monitoring method-
ology and regulatory review, which critically affect
planting success, will be discussed as well.


1) Elevation Planting elevation has long been recog-
nized as the most critical factor in the survival of
emergent marine vegetation. Based on natural distri-
butions of marine vegetation, some authors have sug-
gested that colonization by some species can occur
anywhere within the intertidal zone in Florida (e.g.,
Teas et al., 1975). Other authors have shown that, in


rrpw7. wn~ TP~wi~. 1991


Pace 9







Crewz and Lewis, 1991 Page 10




the short term, optimal elevation ranges for planted
vegetation are much narrower. For example, Stephen
(1984) found that optimal elevations for red (Rhizo-
phora mangle L.) and white mangroves (Laquncularia
racemosa (L.) Gaertn. f.) were at approximately +0.4 m
NGVD. In another study, volunteer black mangrove
(Avicennia germinans (L.) L.) seedlings were abundant
only at elevations above +0.4 m (Detweiler et al.,
1975). The optimal elevation for mangroves at many of
the sites in our study appeared to be approximately
+0.4 m NGVD. Nevertheless, black mangrove propagules
can establish below this elevation during periods of
low water when strong winds delay the return of tides
to higher levels (David Crewz, personal observation).
Some of these plants may persist for several years.
Although white mangroves usually occupy the higher
elevations in mixed mangrove stands under long-term,
stable conditions, our observations (also, see Ball,
1980) suggest that white mangroves grow better at lower
elevations but may be suppressed by red mangrove growth
(e.g., see Bella Vista, Inc.; APPENDIX B). In another
study, better survival of planted red mangroves in
protected sites in the Florida Keys occurred at +0.3 m
NGVD (Goforth, 1984), suggesting that acceptable
planting elevations for mangroves may be lower in the
Keys than in the rest of peninsular Florida. Our data
(e.g., see Coral Shores Estates and Rock Harbor;
APPENDIX A) also suggest that some species are capable
of tolerating lower elevations in the Keys, possibly as
a result of adaptation to synergistic physical factors
characteristic of the Keys (e.g., water quality, marl
substrates, tidal regimes, and others). In fact, lower
elevations may be required in the Keys to offset harsh
substrate characteristics (see Substrate category
below).







Page 11


Saltmarsh vegetation in peninsular Florida extends
over an elevation range similar to that for mangroves.
Unlike mangroves, smooth cordgrass, the principal
intertidal marsh grass in Florida, may have lower
survival and growth near mean high water (Webb and
Dodd, 1989). On steeper slopes, however, smooth
cordgrass may grow well at or above mean high water,
especially if salinity is low (e.g., see Seagrove;
APPENDIX B). Planted smooth cordgrass can survive at
slightly lower elevations (approximately +0.2 m NGVD)
than mangroves and is commonly found growing in deeper
water in front of natural mangrove fringes. In our
study, smooth cordgrass seedlings were found at
approximately +0.3 m NGVD (e.g., see Feather Sound B;
APPENDIX C), and older plants were observed at ele-
vations down to -0.01 m NGVD (e.g., see Bayport B;
APPENDIX C). Clonal plants such as smooth cordgrass
can extend, via intershoot rhizomes, into elevations
not appropriate for colonization; rhizome connections
may provide a physiological buffer (e.g., Lytle and
Hull, 1980) to stresses encountered at suboptimal
elevations. Similarly, red mangroves may extend into
lower elevations by means of branches that "walk" down
from plants established at higher elevations (e.g., see
Campeau Corporation; APPENDIX B). Reduced salinities
may permit better growth at lower and higher elevations
as well.
Elevation is more critical to the survival and
growth of some species than to others. Smooth
cordgrass and white mangroves can survive planting
across a wide range of elevations, but other marsh and
mangrove species (e.g., needle rush [Juncus roemerianus
Scheele] and black mangrove) are more restricted in
elevation requirements. For good growth, needle rush
requires slightly higher elevations than smooth


Crewz and Lewis, 1991







Cewz and Lew..s 1991r...


terpretations from using inappropriate statistical
analyses, we discuss the data (average values, ranges,
etc.) in subjective terms and present it in tabular
form (see APPENDIX D).


Factors Influencing Planting Success

Site failures can be attributed to four general
shortcomings: 1) inferior designs and planning, 2)
inferior construction and planting techniques, 3) poor
monitoring methodology and remedial actions, and 4)
insufficient regulatory review. The first two short-
comings influenced many physical factors that had
immediate effects on vegetation coverage. The physical
factors that influenced vegetation establishment at
these study sites can be separated artificially into
seven categories: elevation, slope and drainage,
substrate, planting rationale, site design, human
intrusion, and plant quality. Separating these factors
into discrete categories is artificial in that inter-
actions among them are complex, and altering values in
one category usually alters values in the others.
These seven categories are discussed in the following
sections in order of their decreasing occurrence among
the sites in this investigation. Monitoring method-
ology and regulatory review, which critically affect
planting success, will be discussed as well.


1) Elevation Planting elevation has long been recog-
nized as the most critical factor in the survival of
emergent marine vegetation. Based on natural distri-
butions of marine vegetation, some authors have sug-
gested that colonization by some species can occur
anywhere within the intertidal zone in Florida (e.g.,
Teas et al., 1975). Other authors have shown that, in


rrpw7. wn~ TP~wi~. 1991


Pace 9







P I 2


cordgrass does, but it dies if planted too high
(Lindeman and Wilt, 1989) or succumbs to competition
from other species if planted too low (Lewis, 1983).
Black mangroves are susceptible to drought stress at
higher elevations that are tolerated by white mangroves
and needle rush or to colonization failure at water
depths that are tolerated by red mangroves and smooth
cordgrass.
In summary, acceptable planting elevations for
mangroves and commonly planted saltmarsh plants are
similar to their natural colonization elevations. In
peninsular Florida, acceptable planting elevations
generally range from +0.2 to +0.6 m NGVD for smooth
cordgrass, from +0.4 to +0.6 m NGVD for needle rush and
black mangroves, from +p.3 to +0.7 m NGVD for white
mangroves, and from +0.3 to +0.6 m NGVD for red
mangroves. Acceptable elevation ranges in the Keys are
probably lower for these same species. Generalized
intertidal locations for some common plant species in
peninsular Florida are shown in Figure 3.
Predictable planting elevations for each species
would serve as a convenient guideline for habitat-
creation specialists, but many variables make it
difficult to recommend precise planting elevations for
the entire state. One of the more important factors
that complicates defining an absolute planting ele-
vation for each plant species is variability in tidal
range and the range's relation to NGVD. Even sites
that are relatively close to each other can have dif-
ferent tidal characteristics, depending on the orien-
tation, narrowness, and depth of access channels. A
site that has a restricted exposure to the marine
system (e.g., a narrow access channel) may, depending
on other factors, have a smaller tidal range than a
more exposed site would. Understanding tidal fluc-


--- a--d- ---1-- 9 ---1 na --


rr~swz anA T.crwice 7901




























--:- -- -- -- --7.:: === ------ z =


SALT FLAT


HIGH MARSH


MANGROVE / LOW MARSH


I 0-2 I 1-50 60-130+ I 60-35 70-25
SEDIMENT SALINITY (PPT)
FIGltRE 3, GENERALIZE) LOCATIONS OF COMMONN INTErTIDAL PLANT SPECIES IN MUD SUBSTRATES OF PENINSULAR FLORIDA. LOCAL
ENVIRONMENTAL CONDITIONS AND THE PRESENCE OF ABSENCE OF CERTAIN SPECIES CAN ALTER THESE RELATIONSHIPS.


AG = AVICENNIA JR = JUNCUS PV = PASPALUM
BF = BORRICHIA LR = LAGUNCULARIA RM = RHIZOPHORA
BH = BACCHARIS MC= MYRICA SV = SALICORNIA
FC= FIMBRISTYLIS ML= MONANTHOCHLOE SA = SPARTINA


ML


ML


UPLANDS


MHHW


MLW


--







Page 14


tuations aids in predicting the flushing charac-
teristics of a site throughout the year and whether
access channels are likely to remain connected to the
marine system at large.
In addition to variations in local tidal charac-
teristics, geographic tidal variations make it diffi-
cult to recommend an absolute planting elevation for a
given species. Tides differ substantially with loca-
tion in Florida (Figure 4) in regard to frequency, high
and low extremes, and duration of tidal events
(Provost, 1973). Tidal ranges in the Indian River
Lagoon, where all of our Atlantic coast sites were
located, are generally lower than in other areas of
Florida. The Florida Keys also have lower tidal
amplitudes. Because tidal ranges are greater along the
northern Atlantic coast of the state, smooth cordgrass
may grow at a wider range of elevations there than it
does farther south. Tidal ranges may be greater at the
mouths of bays and inlets than in inland areas. Water
quality is usually different as well (e.g., temper-
ature, salinity, and dissolved organic matter).
Monthly, seasonal, and yearly variations of tidal
cycles also complicate defining specific planting
elevations for intertidal plant species. Tides
occurring during new- and full-moon phases (spring
tides) rise higher and fall lower than tides during
quarter-moon phases (neap tides). Seasonal and yearly
tidal variations due to moon proximity and declination
also occur. The effects are different for Atlantic and
Gulf coast wetlands (Provost, 1973). Monthly mean sea
level along the Atlantic coast is higher than the
annual mean between September through November (3 mos),
but on the Gulf coast, monthly mean sea level exceeds
the annual mean between May and November (7 mos). If
extreme tidal events are combined with strong winds of


Crewz and Lewis, 1991















'7


1
4


Ti DIURNAL TIDES


'- SEMIDIURNAL TIDES /
/

/ MIXED TIDES


-3- LINES OF EQUAL SPRING-
TIDE RANGE (FEET)


FIGURE 4. TIDAL TYPES AND RANGES IN FLORIDA (AFTER
FERNALD, 1981). DIURNAL = ONE HIGH AND ONE LOW
TIDE PER TIDAL DAY; SEMIDIURNAL = TWO NEARLY EQUAL
LOW TIDES PER TIDAL DAY; MIXED = TWO UNEQUAL HIGH
AND/OR TWO UNEQUAL LOW TIDES PER TIDAL DAY,







Crew an Lews. 991Paffe 16


long duration and the proper direction, entire bay
systems can experience unusually low or high tides that
can affect survival of newly planted vegetation.
If a wetlands site is improperly established at
high elevations, such that spring tides flood it only
once or twice a month, a salt flat may develop as a
result of salt accumulating in the sediment (Figure 3).
An elevation of +0.8 to +1.0 m NGVD would probably
initiate salt flat development (Detweiler et al., 1975)
in peninsular Florida sites with gentle slopes (e.g.,
less than two percent). Sediment salinities over 130
parts per thousand (ppt) are common in vegetation-free
areas of well-developed salt flats (Barbara Hoffman
[USF], personal communication). Interstitial soil
salinities above 90 ppt limit the establishment, sur-
vival, and growth of even the most salt-tolerant plant
species.
Measurement of elevations at a site requires
reference to established benchmarks. Some types of
benchmarks are relatively reliable (e.g., U. S. Geo-
logical Survey) but are often far from thesite.
Nearby structures (e.g., bridge abutments, building
foundations, sewer manhole covers) may have recorded
elevations that can be obtained from local government
agencies (planning departments, FDOT, construction
firms, etc.). However, local benchmarks have become
unreliable in many instances (Dr. Ernest Estevez [MML],
personal communication), and caution should be used
when relying on unfamiliar reference elevations. At
least two benchmarks should be used when establishing a
site-reference elevation.
If reliable local benchmarks are not available, an
alternative and probably more effective method for
establishing planting elevations in a wetlands creation
site is to use local plant populations as a guide.


Crewz and Lewis. 1991


ParrP 16fi







Crewz_ and_ Lewis. 1991 Pae 17


Acceptable planting elevations for a species can be
determined from the elevations of naturally established
juvenile plants in areas as close as possible to the
proposed wetlands site. Using juvenile plants, not
mature adults, as a guide for determining correct
planting elevations is critical. A common mistake is
to assume that all developmental stages of a plant
species (seedling through mature adult) are equally
tolerant of the same tidal elevation. Seedlings are
often less tolerant of environmental extremes than are
well-established mature plants of the same species.
Even with sea-level rise or substrate subsidence, older
plants of all three Florida mangrove species frequently
survive well at tidal elevations too low for seedling
establishment (Figure 5). Some of the confusion in
determining optimal planting elevations for mangroves
and saltmarsh plants probably comes from misinter-
pretations of mature-plant distributions.


2) Slope and Drainage The second most prevalent
shortcoming at the sites reviewed in this study was the
failure to establish slopes that facilitate proper
drainage. Slopes should be established within the
optimum tidal range for the planted species. To
minimize ponding of water as substrates settle, sites
should be designed with the slope towards tidal sources
(e.g., see Bayport B; APPENDIX C). Because steep
slopes provide less area within a suitable tidal range
for growth of marine vegetation, slopes should be as
gradual as possible. For example, increasing a 5-
degree slope to 10 degrees can substantially reduce the
extent of elevations that are optimal for emergent
marine plant growth (Figure 6).
Gentle slopes help small organisms survive during
low-tide periods. Gentle slopes do not drain as exten-


I


Crewz and TLewis. 1991


Pace 17



















































FIGURE 5. MOVEMENT OF RED MANGROVE, AS IT MATURES, INTO
DEEPER WATER THAT IS INAPPROPRIATE FOR SEEDLING
COLONIZATION.












I ix
IMHW
I











X/2



S"-MHW
i- MSL

MLW



FIGURE 6. EFFECT OF SLOPE ON THE EXTENT OF INTERTIDAL VEGETATION ALONG
MARINE SHORELINES, INCREASING THE SLOPE FROM 50 TO 10 REDUCES OPTIMAL
ELEVATIONS FOR PLANTS BY APPROXIMATELY ONE-HALF.







Crewz and Lewis. 1991


sively as steep slopes, and a film of water, in which
small organisms survive, is retained on the surface.
However, gentle slopes are more susceptible to ponding
of water than are steeper slopes. Heavy-equipment
pressure on substrates during excavation often leaves
pockets of lower elevations in which water is trapped
after the tide recedes. These undrained areas are
typically difficult to plant successfully, and
volunteer seedlings do not colonize them (e.g., see
Bayport A and D; APPENDIX C). The probable causes of
plant death are high water temperatures, anoxic sedi-
ments, and hypersalinity resulting from evaporation.
Even when accurate plans are prepared, actual
construction may not achieve the required slope and
elevation tolerances. Completion of as-built topo-
graphic surveys is paramount before construction
equipment is removed from the site, so that slope and
elevation adjustments can be made relatively quickly
and inexpensively. Requiring equipment to return to
the site often produces delays, if the equipment can be
brought back at all. Sites can be checked quickly and
simply for proper drainage by observing tidal changes
across the site for a period of time. Ponded areas can
then be eliminated by installing channels to facilitate
drainage.
The size and number of drainage channels installed
depends upon the size of the site. A broad, shallow.
channel that winds through the site and retains water
at low tide maximizes tidal flushing and plant health
(e.g., see Seagrove; APPENDIX B). Improperly struc-
tured access channels leading into the site may degrade
water quality by inhibiting tidal exchange. A common
mistake is to gouge a basin in the wetlands that is
substantially deeper than the exit, resulting in
stagnant conditions (e.g., see Fountain Cove; APPENDIX


Dn n I


Darrn o3n







Cr ..w. and ....s. 1991 --rx w--


B). At low tide, entrances to enclosed sites should
contain several centimeters of water, and interior
channels should not be much deeper than the entrance
elevations. Sometimes, creation of more than one
access channel--oriented to predominant currents--can
improve flushing enough to prevent stagnation.
Ponded areas can be incorporated into a site to
provide low-tide feeding areas for wading birds such as
wood storks, herons, and egrets. Drainage channels
also improve access to the wetlands for migrating
animals (Minello et al., 1987) and, along with ponded
areas, create low-tide refuges for small animals (e.g.,
crustaceans and fish) that reside in wetlands. Smaller
animals are important components of the plant-based
food web leading to commercially and recreationally
important fish species (e.g., snook, tarpon, redfish,
and spotted seatrout) and to other predators and sca-
vengers, such as raccoons.
Gentle slopes at the margins of the site are also
an important aspect of marine wetlands creation. All
too often, economic pressures to maximize development
of coastal lands result in a failure to consider this
important healthy-wetlands requirement. When suffi-
ciently gradual slopes are constructed, stabilized
vegetated zones around wetlands reduce erosion and
intercept potentially deleterious substances that may
alter habitat quality of the wetlands. If space
restrictions prevent construction of gradual slopes,
stabilization with rapidly growing rhizomatous grasses
or sods is essential to prevent steep slopes from
sloughing into the wetlands and killing planted vege-
tation (e.g., see Harbour Island Fringe; APPENDIX C).
Seedling mangroves are especially vulnerable to
excessive sediment accumulation.


I


Crew7 and T.Pwis. 1991


Pace 21







CPaffe 22


Gradual slopes around the perimeters of construc-
ted sites are instrumental in preventing an insidious
form of habitat loss: long-term loss resulting from
sea-level rise. Because of the specific elevations
required by different plant species, minor changes in
water depth can cause extensive mortality. As a
result, sea-level rise on steep slopes will, over time
and in the absence of sediment deposition, compress
vegetation into narrower zones (Figure 7). This
process requires consideration when areal tradeoffs are
being made in mitigation projects, especially when
marine wetlands with long-term development are
involved. Most of the sites in this survey suffered
from this shortcoming to different degrees.
The rate of sea-level rise is predicted to accel-
erate significantly after the year 2025 (Dreyfoos et
al., 1989). This allows time to alter marine wetlands
creation philosophies and to prepare coastal areas to
accommodate habitat changes resulting from sea-level
rise. Salt flats and transitional uplands with gradual
slopes into wetlands should have low priority as poten-
tial sites for marine wetlands creation and should not
be lowered in elevation, contrary to mitigation recom-
mendations made by Dial and Deis (1986). Uplands with
steep slopes or with seawalls abutting wetlands should
receive a higher priority for mitigation scrapedown.
Although wetlands conservation is a high priority,
undisturbed uplands should not be undervalued in our
zeal to create wetlands.
Poorly stabilized marginal slopes provide
disturbed substrates that are conducive to rapid
invasion by undesirable exotic and indigenous nuisance
species, especially in south Florida. Exotic plant
species, such as Brazilian-pepper (Schinus tere-
binthifolius Raddi) and Australian-pines (Casuarina


Crewz and Lewis 1991


PageP 22


















































FIGURE 7, PROJECTED EFFECT OF SLOPE AT MARINE WETLANDS MARGINS
ON THE EXTENT OF VEGETATION AS SEA LEVEL RISES (IN THE
ABSENCE OF SEDIMENT DEPOSITION).







rrz and- Lewi. 199 24i 9


spp.), often dominate disturbed shorelines and prevent
volunteer propagules of desirable species from becoming
established; this situation is especially prevalent
along shorelines with steep slopes (Figure 8).
Brazilian-pepper is intolerant of interstitial soil
salinities above 5 10 ppt (Mytinger, 1985) but can
become established at higher elevations adjacent to
saline-adapted species, overgrowing them in time. In
these marginal areas, controlling invasion by exotic
and other nuisance plant species requires a long-term
maintenance program involving timely hand weeding,
judicious use of approved herbicides by licensed appli-
cators, and planting of native vegetation (e.g.,
densely clumping grasses [Muhlenbergia capillaris
(Lam.) Trin.; pink muhly]) to retard reinvasion. Some
current regulatory agency policies allow a specified
percentage cover (usually less than 10 percent) of
exotic nuisance plants at each monitoring visit. Con-
trolling nuisance plants, however, requires their total
removal at each monitoring visit, coupled with imme-
diate planting and reseeding with native species. Even
with periodic total removal, nuisance species may
recolonize disturbed substrates of wetlands margins
unless a long-term, multifaceted control program is
instituted. Gradual slopes and buffer zones free of
exotic vegetation improve establishment and growth of
saline-adapted vegetation and, therefore, improve
habitat quality. Wide buffer zones with tall native
terrestrial or transitional vegetation are essential as
faunal sanctuaries, especially for birds and mammals.
Buffer zones adjacent to wetlands provide animals a
refuge from cold winds, high temperatures, high tides,
and storms. In Florida, mature unpruned mangrove
forests provide refuges as well.


I I


Crews and Lewis 1991


Pae 2r 4







Crewz_ and_ Lewis. 1991 Pae 17


Acceptable planting elevations for a species can be
determined from the elevations of naturally established
juvenile plants in areas as close as possible to the
proposed wetlands site. Using juvenile plants, not
mature adults, as a guide for determining correct
planting elevations is critical. A common mistake is
to assume that all developmental stages of a plant
species (seedling through mature adult) are equally
tolerant of the same tidal elevation. Seedlings are
often less tolerant of environmental extremes than are
well-established mature plants of the same species.
Even with sea-level rise or substrate subsidence, older
plants of all three Florida mangrove species frequently
survive well at tidal elevations too low for seedling
establishment (Figure 5). Some of the confusion in
determining optimal planting elevations for mangroves
and saltmarsh plants probably comes from misinter-
pretations of mature-plant distributions.


2) Slope and Drainage The second most prevalent
shortcoming at the sites reviewed in this study was the
failure to establish slopes that facilitate proper
drainage. Slopes should be established within the
optimum tidal range for the planted species. To
minimize ponding of water as substrates settle, sites
should be designed with the slope towards tidal sources
(e.g., see Bayport B; APPENDIX C). Because steep
slopes provide less area within a suitable tidal range
for growth of marine vegetation, slopes should be as
gradual as possible. For example, increasing a 5-
degree slope to 10 degrees can substantially reduce the
extent of elevations that are optimal for emergent
marine plant growth (Figure 6).
Gentle slopes help small organisms survive during
low-tide periods. Gentle slopes do not drain as exten-


I


Crewz and TLewis. 1991


Pace 17











UNDISTURBED


SLOPE


G
E
N
T
L
E





M
O
D
E
R
A
T
E





S
T
E
E
P


DISTURBED


FIGURE 8, EXOTIC NUISANCE-SPECIES INVASION OF MARINE WETLANDS
MARGINS AS INFLUENCED BY THE INTERACTION OF SLOPE AND
DISTURBANCE. E = EXOTIC PLANTS.







Crewz___Pf an Le is 9 p


3) Substrate The third most frequent category of
factors that affected establishment and rapid coverage
by desirable vegetation in the sites we surveyed was
substrate-related variables. The most evident sub-
strate difference among sites was the large-scale
geographic variability associated with the highly
calcareous substrates of the Florida Keys. Although
peninsular Florida marine sediments often contain
concentrations of shell material, most estuarine
sediments are mixtures of sand and fine muds containing
substantial amounts of organic matter. In contrast,
the Keys substrates are composed predominantly of
calcareous marl muds and limerock that contain little
organic matter, except where mangrove peat has accu-
mulated in depressions.
In limerock and packed marl substrates, augers
have been used to drill holes so that mangroves can be
planted. Some success--depending on plant size, site
exposure, and substrate elevation--has been reported
using this technique (Goforth, 1984). If hard sub-
strates are not sufficiently fractured or porous, plant
roots tend to remain in the planting hole, stunting
plant growth. Should the substrate elevations be too
high, plants in hard substrates may suffer salinity and
heat damage in the small auger-hole cups that trap
water when the tide is low (Figure 9; e.g., see Sexton
Cove; APPENDIX A). The effects of hard substrates on
marine vegetation are similar to the effects on plants
in the oriental dish-gardening practice known as
"bonsai," in which restriction of root growth is used
to dwarf shoot growth. Roots of plants cultured in
peat mixes under greenhouse conditions also tend to
stay within the football when installed in marl
conditions, causing the plant to exhibit slower growth


Crewz and Lewis 1991


PaPe 2Fi













ROCK


IMUDI


MHW


MLW


MHW


MLW


FIGURE 9. RESPONSES OF RED MANGROVE SEEDLINGS PLANTED IN HARD (LIMEROCK) AND
SOFT (MARL MUD) SUBSTRATES IN THE FLORIDA KEYS. LEAF SIZE AND NUMBER
INDICATE PLANT VIGOR.







Crewz and Lewis. 1991 P~np 2R


and, therefore, to be less stable (e.g., see Coral
Shores Estates; APPENDIX A).
Substrate composition at a proposed site should be
examined using soil-auger cores. If rock or clay
layers are encountered within the proposed excavation
depth, the site may be unacceptable unless it is sub-
stantially modified. Sand, clay, or marl substrates
may need organic amendment to promote adequate drainage
and to alter physico-chemical qualities critical to
plant and animal colonization, survival, and growth.
In some of the Keys sites, limestone rock was exposed
by grading, and subsequent plant colonization in the
rock area was restricted ,to cracks or pockets that had
a thin veneer of marl mud (e.g., see Cross Street and
Florida Keys Land Trust; APPENDIX A). Underlying rock
formations can also cause differential substrate
settling at a site, resulting in ponding, which causes
plant death (e.g., see Florida Keys Aqueduct Authority;
APPENDIX A).
When uplands are graded to wetlands elevations,
the excavated overburden-soil is often hauled offsite
and used for fill elsewhere. The substrates that
remain in newly constructed sites are often sandy soils
that may be low in organic matter or that may have a
lower bulk density than nearby undisturbed wetlands
soils that have greater clay fractions. Mature, vege-
tated marine sediments are usually more consolidated
than younger sediments and are less subject to movement
by natural physical forces. If care has not been taken
to stabilize marginal slopes adequately, erosion may
transport fine-grained soils from the slopes into the
wetlands. The eroded soil may form a fairly thick,
unconsolidated sediment layer that is subject to
constant resuspension with tidal changes or stormwater
input. These situations can be exacerbated if nearby


Crewz and Lewis. 1991


Parf 9A







Crewz and Lewis. 1991 Paae 29


development funnels nutrient-laden stormwater into the
wetlands (e.g., see Costa del Sol and Fountain Cove;
APPENDIX B). The resulting turbidity blocks light
penetration and increases water-column hypoxia, thereby
decreasing submerged-plant survival rates and growth.
Unconsolidated sediments of young sites may also
provide inadequate support for newly installed plants,
making them vulnerable to erosion (e.g., see Harbour
Island B, APPENDIX C).
Not only do physical substrate factors affect
plant growth, chemical variables can also play a signi-
ficant role. For example, substrates high in organic
material and hydrogen sulfide, as in anoxic red man-
grove peats, can become acidic when exposed to oxygen
during earthmoving activities. Plants installed in
these substrates could suffer a high mortality if pH
values are much below 4.0. The use of calcareous
substrates (e.g., shell), added to buffer acidic
conditions and improve plant survival and growth, has
not been explored, to our knowledge, in relation to
marine wetlands creation. This may be a useful method
for altering chemical characteristics and physical
qualities of the substrate that aid in plant support.
Physico-chemical substrate characteristics (e.g.,
texture, bulk density, nutrient and organic content,
etc.) not only affect plant growth but also affect
microbial and animal populations important to habitat
quality. Several studies investigating sediment vari-
ables in relation to plant survival and macrofaunal and
microbial populations of created wetlands in Florida
are being implemented by the National Marine Fisheries
Service (NMFS; Beaufort, NC), U. S. Army Corps of Engi-
neers Waterways Experiment Station (Vicksburg, MS), and


Crewz and Lewis. 1991


Pace 29







.r ... a.. L. .. ., 1 9 I, .


the Florida Department of Natural Resources, Florida
Marine Research Institute (FDNR FMRI; St. Petersburg,
FL).
Plant growth in newly created sites is often
modified with commercial fertilizers. Fertilizer added
at planting time should be a time-release type that can
be incorporated into the substrate. The major elements
(nitrogen and phosphorus) in time-release fertilizers
should be added as separate time-release pellets
because nitrogen may inhibit phosphorus release under
saturated soil conditions when the elements are in the
same pellet (Mark Fonseca [NMFS], personal commu-
nication). Broadcasting fertilizer is ecologically
unsound in wetlands systems because it contributes to
eutrophication of the water column. Broadcasting
fertilizer in wetlands systems may also have little
effect on plant growth (Broome et al., 1983; Webb and
Dodd, 1989). Follow-up broadcast fertilization in
later years only increases the cost of habitat main-
tenance and extends the period required for plants to
attain nutritional equilibrium.
Adding fertilizer may prove useful for some tidal-
marsh plantings. When rapid growth of grass species
(e.g., smooth cordgrass) is needed on exposed shore-
lines, fertilizer incorporation may improve the resis-
tance of planted vegetation to wave damage. Fertilizer
application containing the equivalent of 112 kg/ha N
and 49 kg/ha P has been recommended (Broome et al.,
1988). Nitrogen and phosphorus applied together
produced greater aboveground biomass of smooth cord-
grass than if only one element was added. To our
knowledge, controlled experiments have not been con-
ducted that adequately define the value of field-added
fertilizer to the establishment of mangroves. Man-
groves respond to light fertilization under nursery


Crews and Lewis 1991


DPar en







CTrw _nd Tw. 1 T'af 31


conditions, indicating a possible positive response if
they are lightly fertilized during field installation.
The presence of nitrogen fixation activity
associated with the roots of unfertilized mangroves
(Zuberer, 1976) and other plants suggests that nitrogen
addition may be superfluous or even harmful. Adding
nitrogen usually inhibits nitrogen-fixing bacterial
populations that are closely associated with plant
roots (Kapulnik et al., 1981). Even low-level,
repeated fertilization may be detrimental to long-term
plant health and population stability because it influ-
ences nutrient and growth-regulator contents of plant
tissues (e.g., Azcon and Barea, 1975). Population
fluctuations resulting from alternating substrate
fertility may lower stress resistance in some plant
species (Crewz, 1987). Although plants may respond
positively to small amounts of fertilizer at planting,
accommodation to predominant long-term substrate
conditions is probably desirable.
Even though limited field fertilization may
increase apparent plant health in some cases, over-
fertilization may produce short- and long-term negative
effects. Overfertilizing plants may alter their root-
to-shoot ratios (from a balanced ratio to a shoot-
dominated value) such that newly installed plants may
become "top heavy" and more .susceptible to uprooting.
The effects of fertilizers on the relationship between
root-to-shoot ratios and plant health in various sub-
strates have not been defined adequately for wetlands
plants.
Overfertilized plants that have higher nutrient
levels and softer tissues may be more vulnerable to
salt damage, pathogens, or herbivory. Extensive mor-
tality resulting from fungal root infections (Fusarium
sp.). was observed in several Indian River smooth cord-


I


Crewz and Lewis 1991


Paep 31







Crewz anid Lewis 1991i D I~ I
---~~ru s - -- -
-Ig


grass plantings that were fertilized at installation
(Steve Beeman [Ecoshores, Inc.], personal communi-
cation). Onuf et al. (1977) have suggested that a
relationship exists between herbivory on mangroves and
the presence of guano from roosting birds, although
this hypothesis has been questioned by some (e.g.,
Johnstone, 1981). The relationship between a plant's
nutrient status and its vulnerability to predators and
pathogens has not been determined for marine wetlands
plant species.
For coastal plantings, then, commonly accepted
agricultural objectives (e.g., large shoots) need to be
modified when they are applied to stress-adapted plant
systems. Other, less apparent characteristics may be
more important to plant vigor and survival than above-
ground size alone.


4) Planting Rationale The fourth category of factors
that influenced planting success at the sites in this
study deals with plant selection and installation
techniques. When the need arises to create marine
wetlands, decisions need to be made concerning which
type of wetlands is desired and which plant species are
needed to produce those wetlands. Marine wetlands
creation in Florida has usually focused on using single
species. For shoreline vegetation, mangrove (esp. red
mangrove) or grass species (esp. smooth cordgrass), or
a combination of the two, have been used in most marine
wetlands creation projects in Florida. Emphasis in
south Florida has shifted to using smooth cordgrass
because it is readily available and easily established
relative to mangroves, which usually colonize smooth
cordgrass stands within a few years (e.g., see Sunken
Island; APPENDIX C). As greater emphasis is placed on
long-term wetlands functionality as the measure of


Crewz and TPwia~ 1991


PDarf e 3







crew and 91Pafe 33


success, complex multispecies plantings should become
more common. Characteristics of plant species commonly
used in coastal habitat creation projects in Florida
are summarized in guidelines produced by the Florida
Sea Grant Salt-Tolerant Vegetation Advisory Panel
(Barnett and Crewz [eds.], 1990).
In our study, 20 sites were totally or partially
planted with smooth cordgrass, 15 sites were planted
with mangroves, and 4 sites were planted with addi-
tional species--e.g., salt jointgrass (Paspalum
vaginatum Sw. [formerly included in P. distichum L.]).
Six sites, in all or part, were not planted. Combi-
nations of plant species were used at many of the
sites. Gulf and Atlantic coast sites were planted
predominantly with smooth cordgrass, and the Florida
Keys sites were planted with mangroves. Unplanted
sites--i.e., those relying on natural colonization--
were most prevalent in the Florida Keys.
In general, sites planted with smooth cordgrass
developed a greater percentage cover sooner than sites
planted with mangroves did, due mainly to the rhizo-
matous nature of smooth cordgrass. Compared to the
Gulf and Atlantic coast sites, the Florida Keys sites
were slower to develop vegetation cover; this was due
to their relatively organic-poor limerock and marl
substrates, the practice of relying on natural recol-
onization (see below), and the predominant use of
mangroves at the Keys sites.
Mangroves Mangroves can be obtained from nurs-
eries and usually range in age from one to five years.
One- to two-year-old red mangrove seedlings have been
used in most mangrove plantings. Care should be taken
when purchasing rooted red mangrove seedlings to select
plants that have not had the propagules inserted into
the.potting soil too deeply--i.e., greater than six cm.


Crewz and Lewis 1991


Pacre 3RR







Darro 3A


Although deeply inserted red mangroves may survive in
culture, once they are installed in the field any sedi-
mentation that occurs may adversely affect growth or
may lead to suffocation and death. These plants may
not tolerate as low a planting elevation as properly
rooted nursery plants do.
Older plants (three-gallon pots and above) are not
as common as the one- to two-year-old class and may be
root-bound if they have been held in the nursery for
long. Root-bound mangrove saplings may exhibit a
dormant period following field installation. Failure
to establish a good root system quickly may result in
the death of the plant. Therefore, caution should be
used when selecting older plants to ensure that they
are properly potted. Plants larger than those in
three-gallon pots greatly increase the cost of a
project, but few, if any, nurseries stock larger
mangroves.
In-kind replacement of damaged large mangroves is
prohibitively expensive. Estimates of the 1990 cost of
growing a single red mangrove to five meters in height
and 4-m2 coverage, installing it, and guaranteeing its
survival may be in excess of $11,000 (Judy Milam [Flor-
ida Natives Nursery, Inc.], personal communication).
Mitigation for illegally damaged large mangroves may be
one situation in which larger plants could be required.
These plants would most likely come from field trans-
plants of large mangroves destined for "unavoidable"
destruction.
Unrooted red mangrove propagules can be planted
and are readily available in-season from natural popu-
lations. The direct installation of red mangrove
propagules has been popular due to their low cost and
ease of collection during late summer and fall. Red
mangrove propagules have several advantages over rooted


O w and T-i 19C1 D I


P~-PG17 ~~~ T.Pf.~ic: 1991






Crewz ;lnd T.~i 19


- a ---L- ~--9-i ----


seedlings. First, because propagules are less expen-
sive, a greater planting density is possible, which
could produce a more genetically diverse habitat
sooner. Cost savings from using propagules should not
be used to justify larger planting areas if using nur-
sery stock provides an advantage. Greater densities
should always be required when using red mangrove
propagules. Second, because propagules have not been
influenced by nursery culture conditions, they adapt
more readily to the habitat in which they are
installed, thereby avoiding acclimatization shock.
Third, propagules are not as subject to damage from
wind, which may blow over top-heavy potted seedlings.
When planted at the proper elevation in sheltered
areas, red mangrove propagules may survive at least as
well as older, nursery-grown plants (e.g., Goforth,
1984). Stephen (1984) reported 97 percent survival of
planted red mangrove propagules after eight months at a
protected site in Naples, Florida (Windstar on Naples
Bay). In 1990, most of the planted red mangroves at
this site were still alive, although some had died
because of poor drainage in parts of the site. Most of
the red mangroves were about three meters tall with a
22 percent increase in density; however, some red
mangroves in parts of the site were scrubby (ca. one
meter tall) with a 54 percent decrease in density for
those areas (Proffitt and Devlin, in preparation).
Unqualified use of red mangrove propagules in
preference to nursery-grown stock is not always advan-
tageous. Properly staked, rooted seedlings may be
better to use than propagules in less stable sites,
where shifting sediments and water movement can easily
uproot propagules. Rooted mangrove seedlings can be
planted at slightly lower elevations than propagules
can-because of the better transpiration afforded by


P~I )







Crwz __nd T_~wis. 1991 Pa 36


leaves on rooted seedlings. Rooted seedlings can also
provide greater plant cover over the short term than
propagules. Finally, rooted seedlings are available
year round; propagules are only available during late
summer and fall and cannot be stored for long periods.
The small propagules of black mangroves and white
mangroves (Figure 10) are impractical for direct
installation because they must remain on a damp sub-
strate for several days to germinate and anchor prop-
erly (Rabinowitz, 1978). High elevations or steep
substrate slopes result in desiccation or removal of
propagules by tides. Lewis and Haines (1981) reported
poor establishment when broadcasting propagules of
these species. Therefore, these two species generally
require nursery production to a size appropriate for
field planting (i.e., greater than 30 cm in height).
A situation in which broadcast dispersal of black
mangrove and white mangrove propagules may be appro-
priate is into a dense stand of smooth cordgrass estab-
lished at proper elevations. Dense stands of smooth
cordgrass trap mangrove propagules and apparently
enhance mangrove survival and growth (Lewis and
Dunstan, 1975), thereby serving as a "nurse" plant.
The role of smooth cordgrass as a nurse plant may be
related, in part, to reduction in solar incidence and
desiccation during the mangrove's vulnerable estab-
lishment phase. Propagules of all three mangrove
species can be collected and scattered among smooth
cordgrass shoots and have a greater likelihood of
establishment. Establishment of mangrove forests along
shorelines subject to moderate wave energies could be
approached via this technique. Even though the proce-
dure would require two or three years to implement, the
probability of mangrove establishment and increased
quality of habitat, in terms of rapidity of mangrove


rP-W7. and T,ewis. 1991


Paae 36










1


BLACK


FIGURE 10. FRUITING PROPAGULEE) CHARACTERISTICS OF FLORIDA
MANGROVE SPECIES (MODIFIED FROM BARNETT AND CREWZ, 1990).


WHITE


I .r







Crewz anid Lewis 1991i D I~ I
---~~ru s - -- -
-Ig


grass plantings that were fertilized at installation
(Steve Beeman [Ecoshores, Inc.], personal communi-
cation). Onuf et al. (1977) have suggested that a
relationship exists between herbivory on mangroves and
the presence of guano from roosting birds, although
this hypothesis has been questioned by some (e.g.,
Johnstone, 1981). The relationship between a plant's
nutrient status and its vulnerability to predators and
pathogens has not been determined for marine wetlands
plant species.
For coastal plantings, then, commonly accepted
agricultural objectives (e.g., large shoots) need to be
modified when they are applied to stress-adapted plant
systems. Other, less apparent characteristics may be
more important to plant vigor and survival than above-
ground size alone.


4) Planting Rationale The fourth category of factors
that influenced planting success at the sites in this
study deals with plant selection and installation
techniques. When the need arises to create marine
wetlands, decisions need to be made concerning which
type of wetlands is desired and which plant species are
needed to produce those wetlands. Marine wetlands
creation in Florida has usually focused on using single
species. For shoreline vegetation, mangrove (esp. red
mangrove) or grass species (esp. smooth cordgrass), or
a combination of the two, have been used in most marine
wetlands creation projects in Florida. Emphasis in
south Florida has shifted to using smooth cordgrass
because it is readily available and easily established
relative to mangroves, which usually colonize smooth
cordgrass stands within a few years (e.g., see Sunken
Island; APPENDIX C). As greater emphasis is placed on
long-term wetlands functionality as the measure of


Crewz and TPwia~ 1991


PDarf e 3







Paae 38


coverage, would be greatly enhanced. This technique
would also allow mangroves to be planted at slightly
lower elevations than they could tolerate when planted
alone, thereby providing a more immediate enhancement
of marine productivity.
Field-collected mangroves are not recommended
because transplanting causes damage to natural mangrove
habitats and is labor intensive. State regulations
(e.g., F.S. 403, dredge-and-fill; FAC 17-321, mangrove
protection) prohibit unpermitted habitat disturbance or
mangrove damage that occurs during transplanting.
Nevertheless, guidelines for transplanting smaller
mangroves have been developed (Pulver, 1976). Suc-
cessful establishment was reported with trees less than
60 cm tall, when transplanting was done properly.
Other evidence suggests larger trees are more difficult
to transplant (Teas, 1977). The long-term value of
using larger transplanted trees rather than smaller
nursery-grown plants may not justify the effort
involved in the energy-intensive and habitat-damaging
transplanting process. In one study, transplanted 12-
to 18-month-old red mangrove seedlings did not exhibit
better survival than propagules did, and propagules had
significantly greater vertical growth after five years
(Goforth and Thomas, 1980).
Smooth Cordqrass Plugs and bare-root culms of
smooth cordgrass (Figure 11) are easily transplanted,
and nursery-grown units produced from field-harvested
culms are easy to handle and install. Shoot die-back
may occur after planting, but this does not necessarily
indicate death of the planting unit. Root-crown buds
may still be viable, and some units should be dug up to
confirm viability before replanting the site. As with
mangroves, permits to remove smooth cordgrass and other
marsh plants from coastal wetlands must be obtained


__


UI-y- and T-ewi s l qq- -


rrPb17 wn~ T,~wic~~ 1991





























SPIKELET
(CONTAINS SEED)










MOan








FIGURE 11. SMOOTH CORDGRASS VEGETATIVE AND SEED-
PRODUCTION CHARACTERISTICS (MODIFIED FROM
BARNETT AND CREWZ, 1990),







Crewz_ and__ Lewis. 199 Pc 4


from the proper authorities. If transplanting smooth
cordgrass is permitted, donor-site damage should be
minimized. Removing narrow strips (1 m wide or less)
perpendicular to the tidal gradient/shoreline allows
for rapid regrowth (Penny Hall-Ruark [FDNR-FMRI],t
personal communication). Even minor disruptions of
marsh sediments interfere with some wetlands functions,
and transplanting should be prohibited unless marshes
are specifically constructed as donor sites.
In contrast to northern smooth cordgrass popu-
lations (e.g., North Carolina), seed production is
patchy in south Florida populations, and seeds have not
been available. Low seed production may be due to
failure of seed set and to damage of the grass
spikelets by insects and pathogens (David Crewz,
personal observation). The general failure of south
Florida populations to set seed may be related to
environmental effects on the breeding system of smooth
cordgrass at lower latitudes. Smooth cordgrass is
protogynous, with stamens producing pollen before most
of the stigmas become receptive. Environmental condi-
tions may reduce variability of sex expression enough
that pollination may be reduced, especially in the
small, isolated populations typical of south Florida.
Bertness et al. (1987) observed high rates of seed
and flower predation in Rhode Island populations of
smooth cordgrass but determined that late-season seed
production was high enough to compensate for early-
season losses. They suggested that not only did seed
predation directly affect seed production, flower
predation .indirectly affected seed production by
reducing pollen availability, leading to reduced
pollination. If smooth cordgrass escapes overpredation
through late-season flowering, indiscriminate har-
vesting of early-flowering plants, especially from


Crewz and Lewis. 1991


Paae 40







Crewz ~nc9 T~~i ic0a


Crew andLews 101 rge i41


small populations, could result in man-made wetlands
with a phenotypically homogeneous plant population.
These populations may be vulnerable to epidemic
predator and pathogen damage and to reduced seed set.
Studies that better define genetic and reproductive
characteristics of coastal plant populations are needed
so that bottlenecks in creating self-maintaining
wetlands can be minimized.
Other Species High-marsh species (e.g., needle
rush, saltgrass [Distichlis spicata (L.) Greene],
marsh-hay [Spartina patens (Ait.) Muhl.]) and low-
salinity marsh species (e.g., saw-grass [Cladium
jamaicensis Crantz] and giant leather ferns [Acros-
tichum spp.]) have been used in wetlands creation
projects. The few attempts to plant needle rush have
had mixed success because its lateral spread is slow
and establishment of proper elevations is critical to
prevent its elimination by other species. Planting
needle rush on 30-cm centers as a maximum was recom-
mended (Lewis, 1983). Although nurseries stock some
plant species from low-salinity marshes, many species
are not commonly available at present. Creating low-
salinity marshes often requires using field-harvested
seeds and plants, which may have variable survival
(e.g., saw-grass; A. Shuey [FDER], personal communi-
cation). Establishing proper hydrology is critical to
saw-grass survival.
Density Planting density, in addition to species
composition and plant size, influences the rate of
wetlands development. Historically, planting on one-
meter centers has been recommended for most marine
wetlands creation projects. This density is derived
from early, unregulated wetlands creation attempts
where densities were essentially a compromise between
the..number of plants a consultant could provide and the


T"*-^, ,- -^







, A T.er. c_- 1001 Q P 4


client's willingness to pay. Denser plantings are
often required when smaller plants are used or if rapid
coverage is desired. Occasionally, lower densities are
used with larger plants (e.g., three- to seven-gallon
mangroves).
For smooth cordgrass, vegetative coverage is not
governed solely by planting density. If surviving
smooth cordgrass units are evenly distributed through-
out the site, they may provide acceptable areal cover-
age within the desired time frame, even if overall
survival is substantially lower than specified in
permits. By comparison, mortality effects in mangrove
plantings are amplified by the low densities at which
they are planted and by their slower rate of coverage.
In areas that have appropriate substrates, elevations,
and propagule availability, the number of potential
colonization opportunities by mangroves is usually much
greater than the normally recommended planting density.
Death of young mangroves in dense, naturally colo-
nized stands is normal. For example, Pulver (1976)
measured the density of young, even-aged, natural
mangrove stands. The density of red mangroves in his
survey decreased from 26.8 trees/m2 in stands averaging
1.2 m tall to 8.3 trees/m2 in stands averaging 1.9 m
tall. Even though this represents survival of only 31
percent between stages, the overall "quality" of sur-
vivors may be better because of elimination of less
vigorous individuals. For slow-spreading mangroves,
planting densities that emulate natural colonization
rates may be more appropriate for wetlands creation
than the sparse densities normally used in past
*projects.
Red mangrove propagules should probably be planted
no greater than 25 cm apart, and one-year-old mangrove
seedlings no farther apart than 50 cm, especially in


Panm 42


~,,,~,o ~nr7 T.nr.lic 1QQ1







Crewz~~'D an ei.19 AlI


the Keys where growth may be retarded by poor sub-
strates. Planting large areas on 25-cm centers instead
of one-meter centers increases the number of planting
units by at least ten-fold, and planting on 50-cm
centers by four-fold; the relative increases depend on
site size and shape. Because of the increased cost of
denser plantings, a distinction between restoration and
mitigation projects should be made in regard to the
densities recommended above. Mitigation efforts
attempt to offset upcoming habitat losses or after-the-
fact illegal damage, and denser plantings should be
required to minimize time-related wetlands loss while
the site is developing. Restoration projects, which
offset historical losses, can be planted at more
economical densities that permit reclamation of larger
areas. In the case of restoration, plant failure can
be offset by replanting or by relying on natural
colonization.
Although emulation of natural mangrove coloni-
zation densities may seem economically unreasonable,
increased planting densities for nonclonal plants will
likely result in a reduction in time-related habitat
loss because the vegetation reaches a greater coverage
quicker. Rapid areal coverage by planted mangroves
would be better assured if planting densities were
required to approach natural recruitment rates.
Implicit in the view that mangroves must be planted to
speed up mangrove habitat regeneration is the assump-
tion that natural mangrove recruitment would not
provide as much areal coverage as planted mangroves
would within the same time frame. However, some
.substrates may be rapidly colonized by mangroves during
the propagule-drop period (especially by black or white
mangrove seedlings). The key to encouraging natural
colonization is to establish protected, appropriate


Crewz and Lewis. 1991


oDmm n







Crewz and Lewis. 1991


wetlands elevations and slopes near reproductive
sources. Each site has unique characteristics that may
necessitate pilot projects to confirm the feasibility
for using this technique.
Given the limited availability of funds for marine
wetlands creation, a common argument for eliminating
mangrove planting in favor of natural recruitment is
that it would allow more economical creation of larger
wetlands. Nevertheless, this technique should not be
regarded as an option for most sites, especially those
involving mitigation. The prime shortcoming of this
nonplanting approach is that predicting rapid coverage
by a particular species is not possible, so creating
specific wetlands types could not be guaranteed. The
credibility of this approach is reasonable only if
results are measured against the historically low
planting densities specified for mangrove habitat
creation.


5) Site Design Variability in site design--in regard
to size, location, and structure--was the next most
common category of physical factors affecting vege-
tation development at the sites in this study. In
addition, an important component of a good site design
is early site-preparation planning, which enhances
timely implementation of the planting effort.
Site size, although not a major concern in plant
establishment, can affect the rate of vegetation
coverage if large sites are planted at lower densities
than small sites. Site size should not determine
planting density, but rather, densities proven to
accelerate plant coverage should be used to lessen
short-term wetlands losses for projects requiring
mitigation. To offset both immediate and long-term
wetlands losses, larger marine wetlands that have


Paae 44







r9Pama AR


complex transitional margins should be created so
wetlands can move inland as sea level rises. Larger
sites provide a better opportunity for creating complex
.wetlands having a diversity of species and elevations.
Larger sites also provide better habitat qualities in
areas close to large human populations. In response to
mitigation concerns, regulatory agencies may require
large sites to offset even small losses of existing
natural wetlands. Loss of wetlands acreage involves
not only an areal component but also a temporal com-
ponent that reflects the time it takes the created
wetlands to mature. To measure wetlands loss accu-
rately, it should be expressed as a space-time value
(i.e., acre-years) so that mitigation trade-offs
realistically offset losses. For example, wetlands
that take 25 years'to reach maturity would justify an
acreage trade-off ratio that is much greater than 1:1.
At its extreme, the trade-off ratio might be 25:1,
although this is unlikely.
Location and structure are important to site qual-
ity for three reasons: wave energy, wetlands accessi-
bility to marine organisms, and logistics. Ample
documentation exists that mangroves by themselves are
not generally suitable for use on exposed or eroding
shorelines (Savage, 1972; Teas, 1977; Goforth, 1984).
Unstable shorelines exposed to moderate wind and water
movement should be planted with smooth cordgrass, at
least initially. In Chesapeake Bay, smooth cordgrass
was unaffected by wave energy if fetch exposure was
less than one nautical mile (Hardaway, 1986). Between
1.0 and 3.5 nautical miles of fetch, some replanting
was necessary, and over 3.5 miles of fetch, a wave-
barrier device was required to protect plantings.
Sites with fetches over 5.5 miles were not recommended
for.planting of any kind. Smooth cordgrass survives


CrewZ and Lewis 1991


'Pagre 45







Page 46


and grows better in dynamic habitats than mangroves do,
and it has been widely used in shoreline plantings
throughout Florida. Mangrove plantings have been
limited to protected waters in southern parts of the
state.
Protecting planted shorelines with proximal off-
shore structures is necessary at many sites to allow
vegetation development that can resist moderate wave
.energy. Structures composed of large rocks perform
better than shell or sediment berms, which restrict
tidal flushing and may collapse or erode into wetlands
(see Bayport A; APPENDIX C). Mangroves have been
planted behind coquina rock berms set to a height of
approximately MHW in wetlands mitigation in the Keys
(FDOT); open spaces between the rocks allow complete
water exchange. Where the berms were constructed
properly, they functioned as intended and trapped many
new propagules.
In addition to wave-energy effects, the location
and structure of a site can influence habitat quality
by limiting access to the site by marine fauna and
flora. If damaged wetlands are mitigated offsite, the
new location may have a different salinity, soil struc-
ture, hydrology, or relationship to uplands buffer
areas and to deeper channels used as migration routes
by fauna. Prevailing currents and winds may transport
colonizing plant propagules away from the area, thereby
preventing additional plant colonizations.
Marine wetlands are often constructed where proper
site design is hampered. Existing wetlands vegetation
may interfere with constructing fully functional
wetlands. For example, preserving isolated mangrove
clumps may not protect installed plants but, instead,
may restrict tidal exchange by creating berms. During
permit development, regulatory agency personnel should


Crewz and Lewis, 1991







Crew an e
It


emphasize enhancing the functional qualities of wet-
lands over minor structural concerns. Sound ecological
judgement must be used in assessing whether existing
vegetation impairs or contributes to developing the
functional wetlands attributes at the site.
Even though uplands may be available for modi-
fication, the upland's location may be inappropriate
for marine wetlands creation, especially when modified
for mitigation purposes. Some wetlands sites are
constructed in areas which may be of lower value to the
landowner and which may lack sufficient area for con-
structing gradual substrate slopes, wide buffer zones,
or adequate connections to the marine system. Under
these conditions, enclosed sites are "shoe-horned" into
available property that may be poor mitigation for lost
natural wetlands. Environmental conditions in enclosed
sites may be subject to greater fluctuations than occur
in sites with relatively unrestricted tidal exchange.
Sites where substantial freshwater input reduces salin-
ity are preferable for creating oligohaline habitats
(Rozas and Hackney, 1983), but under these conditions,
site structure that restricts tidal exchange may be
unacceptable when planting saline-adapted species. For
example, a site with a narrow flushing channel may
become unintentionally oligohaline or eventually eutro-
phic if it also serves as a stormwater catchment basin
for nearby development (e.g., see Costa del Sol and
Fountain Cove; APPENDIX B). Some undesirable oligo-
haline species, such as southern cat-tail (Tvyha
domingensis Pers.), can persist in higher salinities if
oligohaline conditions are present during the estab-
lishment phase (Zedler, 1984). At the other extreme,
sites that lack adequate tidal exchange or freshwater
input may become hypersaline, causing plant death and
changes in habitat quality.


Crewz and Lewis. 1991


Darr A 7







Crewz and Lewis. 1991


Another aspect of a well-planned site design
concerns the ease with which construction personnel can
transport equipment to the site. If ecological con-
cerns are not an issue, creating easily accessible
sites can significantly reduce costs associated with
construction and monitoring. Seasonal weather condi-
tions can delay repair of site problems or delay
monitoring programs at sites only accessible by boat.
Remote sites are less vulnerable to human intrusion
than are sites that are easily accessible (e.g., see
Sunken Island; APPENDIX C).
Proper planning is essential for implementing a
successful planting. Expeditious wetlands creation
begins with an ecologically sound planting plan but
hinges upon having the proper permits in hand prior to
construction. Several regulatory agencies may have
jurisdiction over an area, and approval may be required
from each if the project is of a sensitive nature. A
planning strategy that increases survival of plants is
important, but protecting adjacent habitats, as man-
dated by regulatory agencies, is also necessary.
Regulatory agencies usually require placing hay bales
and silt screens around the site when uplands are
graded to wetlands elevations. Arrangements must be
made to obtain the necessary protective devices and
have them at the site before earthwork begins.
In addition to site preparation and permitting
concerns, proper scheduling of planting events is
essential to successful plant establishment, especially
when plant supplies are likely to be limited. For
example, installing red mangrove propagules is limited
to the propagule-drop period during the summer and
fall. Similarly, if large quantities of certain types
of planting units are needed, longer lead times may be
required for contracting nursery plant production.


Paae 48







Crewz and Lewis. 1991


'D= AC


Large projects are often delayed by unforeseen events,
however, and plants contracted for that project may
require holding in the nursery. Contingency plans
should be made for distributing contract-grown plants
elsewhere, if they are not used within a reasonable
time.
Other scheduling considerations involve avoiding
stressful environmental conditions such as extremely
hot or cold weather, extreme tides and wind, or low-
rainfall periods. Although capable of tolerating
higher salinities, many salt-tolerant plant species
produce more biomass at lower salinities (10 20 ppt).
Planting while salinities are lower during rainy
periods usually improves establishment and growth. The
driest times of the year in peninsular Florida occur in
the spring, and to a lesser degree, in the fall.
Although these periods are acceptable for planting,
better survival might occur if planting is done in the
wetter months between June and September. High summer
temperatures may reduce survival rates of recently
installed plants, especially if they were raised under
relatively benign nursery conditions. Local weather
reports should be consulted for appropriate planting
periods to determine when plants should be moved to the
site.
In addition to concerns about salinity and tem-
perature, damage to recently installed plants by
extreme tides during full- and new-moon phases should
be avoided. Planting during neap-tide periods and in
the spring months can reduce the likelihood of extreme
high tides damaging newly planted vegetation.


6) Human Intrusion Although human intrusion was not a
prevalent detrimental activity at most of our sites, it
can.be extremely harmful at any single site. Direct


Dae A Q







Crewz and Lewis. 1991 0 !J
-- L.', -. a


damage from trampling, mowing, mangrove pruning,
digging for bait (e.g., for fiddler crabs), vehicles,
dumping, and vandalism can seriously impair wetlands
quality (e.g., see Bayport A; APPENDIX C). Other
indirect anthropogenic effects on wetlands that are
less overt but that still impair site quality are
altering freshwater input into wetlands through
ditching or blocking sheetflow; producing toxin and
nutrient runoff from roads, farms, and lawns; spraying
for mosquitos; promoting exotic species invasion
through mangrove pruning; encouraging domesticated
animal damage; promoting erosional deposition; and
regularly disrupting animal activities (e.g., nesting,
roosting, feeding) through human presence (e.g., docks,
boating, field naturalists). A site's proximity to
high-population urban areas increases its probability
of being damaged and the need for protection. Some
plant species (e.g., smooth cordgrass), because of
rapid rhizome expansion, are more resilient to dis-
turbance than other species are (e.g., mangroves).
Sites vulnerable to public access should be protected
with structures that deter intrusion. Signs can be
posted--until they are vandalized--at likely access
points, and barriers such as fences, waterways, or
vegetated buffer zones should be used wherever possible
to discourage trespassers.
If humans wish to enter a site, barriers will only
slow them down. Making sites less apparent by con-
structing vegetated buffer zones around them can
function as a significant deterrent to trespassers. As
mentioned earlier in the discussion concerning slope
effects in adjacent uplands, buffer zones act as
important insulators for wetlands. Zedler (1984)
summarized the values of buffer zones and provided
guidelines for their use in California. Buffer zones


Crewz and Tc~wis. 1997


P*D 5n







.Crwz and L.wis. 1991 .... 1


around wetlands reduce their vulnerability to chronic
and extreme natural events as well as to human activ-
ities. All sites should include a buffer zone of such
a size (e.g., greater than 50 feet wide) that human
intrusion is discouraged, at least until the regulatory
agency responsible for monitoring has deemed the
creation a success.


7) Plant Quality The seventh and last category of
physical factors that modified vegetative success at
the sites in this study deals with how plants were
handled before and during preparation for planting.
Plant survival and growth following field planting may
be affected by the conditions under which they were
raised in nurseries. Many plants used in saline
wetlands creation are cultivated with fresh water, but
planting nursery stock into conditions where salinity
is over 15 20 ppt may result in lower survival. In
California, Spartina foliosa Trin. seedlings cultured
in fresh water occasionally had poorer long-term sur-
vival when planted in saline soils (Zedler, 1984). To
overcome this problem, nursery stock is usually accli-
matized to saltwater by gradually increasing the
salinity of the culture conditions over a period of
several weeks prior to planting. Even gradual accli-
matization to higher salinity may not be sufficient to
ensure acceptable short- or long-term survival of
installed plants. For optimum survival, plants
destined for saline environments should be raised under
a constant salinity influence so that tolerance is
developed in all plant parts, not just the most
recently developed segments.
Mangroves, especially blacks, raised in fresh
water may be sensitive to planting in higher-salinity
conditions. Mangroves must maintain an osmotic


CrPWx wnrf Tnwis. 7991


Paap 51







Cr ,wz a ..nd1 1-- --51--


pressure lower than that of seawater to obtain fresh
water and nutrients for growth. Freshwater-cultured
mangroves planted in high salinities could lose water
from their roots, causing death. Mangroves raised in
fresh water also have lower tissue salt content and may
be subject to greater herbivory and pathogen damage
(David Crewz, personal observation).
Different species and plants of the same species
from different geographic regions may require alter-
native plant-culture techniques to produce optimal
growth forms. As mentioned previously under the
section on substrate concerns, the limerock and marl
substrates in the Florida Keys are difficult to plant
and may require nursery culture methods different from
areas where soils have a higher organic content. Tech-
niques for growing these plants in marl mixes--instead
of the usual peat-based formulations--should be devel-
oped by nurseries involved in raising plants for
wetlands creation in the Keys. Plants raised in this
manner could be preadapted to predominant sediment
qualities and would therefore probably suffer lower
stress following planting.
Because nurseries must grow plants efficiently to
maximize profits and remain competitive, little infor-
mation has been generated concerning production of
stress-adapted plants for marine wetlands creation
projects. Research in this area is needed to generate
support for regulations that control the growing condi-
tions for plants that will be installed in stressful.
environments. Regulations would also protect estab-
lished nurseries committed to proper plant culture
.against unfair competition from businesses that grow
plants expediently. To assess the effects of culture
techniques on plants destined for marine wetlands
creation, FDNR-FMRI is constructing two one-quarter-


Clrnwn ~nr3 TpWiS. 7qq7


Paae 52







Crew and Lewis- 1991 c
age


acre wetlands mesocosms at the State's Stock Enhance-
ment Research Facility/Plant Production Research
Facility (SERF/PPRF). The PPRF mesocosms are
controlled-tide systems to be used for investigating
submergent and emergent plant species growth charac-
teristics and faunal interactions.
Transport methods and on-site handling of plants
can also affect the success of the planting effort.
Plants should be kept cool, moist, and out of direct
sunlight during transport. Red mangrove propagules may
be damaged from excessive exposure to sunlight and lack
of moisture, so protection of the propagules during
mid-day hours is important. To prevent drying, plants
should not be moved to a site until they can be planted
without delay; holding plants in boxes or without water
at the site for several days will decrease their
chances of survival. At one site in this study (Coral
Shores Estates; APPENDIX A), death of red mangrove
seedlings was attributed to their being cultured two-
to-a-pot and then ripped apart for single installation
(Curtis Kruer [ACOE], personal communication). Woody
plants should be raised under nursery conditions as
individual planting units and should not be subjected
to extreme football damage when planted. Herbaceous
plants are less sensitive to mechanical damage than are
woody plants and may even benefit from football dis-
ruption when planted.
Transportation of plants between widely separated
geographic regions is also of concern. The principal
reasons for placing restrictions on plants imported
from foreign populations are concerns about trans-
porting exotic organisms between regions and concerns
about diluting locally adapted genetic stocks. Some
evidence suggests that substantial intraspecific
genetic variation between Gulf and Atlantic coast plant


Crewz and T~FWjS. 7991


PD-syo 53







Paae 54


populations (e.g, Wain, 1982) or between those from
different latitudes (e.g., McMillan, 1975; Johnston,
1986) may occur. In principal, plant materials should
originate from areas as close as possible to the
wetlands creation site. Much resistance from business
interests has been met in regard to limiting donor-site
locations because of the general unavailability of some
plant species in certain areas and the regional nature
of some businesses involved in marine wetlands creation
work. For example, a nursery on the Atlantic coast of
Florida that has access to a large supply of smooth
cordgrass from marshes in that vicinity may wish to bid
on creation projects on the Gulf coast; current poli-
cies may prevent the use of those plants. More and
more project specifications require using locally
obtained plants, which may not be available when
needed. A study is underway to assess genetic varia-
bility among Florida populations of smooth cordgrass.
Common-garden experiments at the SERF/PPRF will deter-
mine if genetic variability exists among populations
and is maintained under similar culture conditions.


8) Monitoring The last, but certainly not the least
important, factor instrumental in assuring efficient
wetlands creation concerns proper follow-up activities
that are part of a formal monitoring program. Evidence
for the need for strict control of post-planting site
conditions is reflected in the damage occurring at many
of the sites surveyed in this study. Many sites
suffered slope erosion, damage and encroachment from
adjacent construction, debris impacts, and drainage
impairments, to name only a few disturbances.
The permitted is currently responsible for funding
and implementing monitoring programs. Consulting firms
are usually hired by the permitted to design and


1_1 A T zu Lta i c! 1001 -


~r~r.rn ~n~ T.6TliC 1007








Crew an Lews. 991Paffe 55


perform monitoring requirements specified by regulatory
agencies. At present, the financial relationship
between the permitted and the consulting firm is
usually confidential. If the monitoring reports fail
to reach the regulatory agency, culpability may be
difficult to pinpoint, especially if the permitted's
company or property has changed ownership. Regulatory
agencies may need to decide how monies will be allo-
cated for monitoring programs to ensure that permit
requirements are fulfilled. Companies that design and
construct a site may not be rigorous enough in subse-
quent monitoring evaluations. To avoid bias in site
evaluations, monitoring should probably be performed by
a different firm chosen randomly from a regulatory
agency's approved list.
Regulatory agencies generally recognize that
monitoring is important, but efficient implementation
of a valid monitoring program is much more difficult
and time consuming than first impressions might
suggest. Following site creation, appropriate moni-
toring methodology must begin with a description of the
biotic and abiotic characteristics of a site and with a
time-zero report submitted to the regulatory agency.
As-built drawings, which provide regulatory agencies
with information to assess the development of the site
at future monitoring intervals, should be required.
These drawings (large-scale maps) should include
detailed locations of plant species, reference stakes,
bench marks, soil types, slopes, elevations (topo-
graphic contours), and tidal ranges. Plant locations
should be separated by species because future moni-
toring evaluations of success are based on these
initial plant distributions. Reference stakes that
define plant locations should last through the
monitoring period; aluminum or galvanized stakes are


Crewz and Lewis. 1991


Pae 55







Page 56


durable and resist movement. In particular, a semi-
permanent concrete benchmark should be established
on-site to allow measurement of substrate elevation
changes over long periods and measurement of design
requirements in the proposal. Care should be used to
reference at least two reliable elevations to establish
the benchmark.
Because drastic substrate changes occur in some
sites, soil-type distributions should be described on
as-built drawings. Wetlands and wetlands margins
slope-data provide information on drainage patterns and
erosion potential. Also, elevation data (especially
topographic contours) aid in the monitoring evaluation;
topographic contours should be measured at no greater
than six-inch intervals. Other elevation data that
should be indicated on as-built drawings are the
highest and lowest planting elevations around the site,
channel topography (if applicable), elevations of
anomalous structures (e.g., rock outcrops), and ele-
vations of adjacent wetlands communities. Tidal ranges
are related to elevation and substrate qualities and
should be shown on as-built drawings as well. Tidal
information should include low and high tides on the
days of planting and on the next spring and neap tides.
Along with as-built drawings, information on
planting dates and densities of each species should be
included in the initial report. Each plant (woody
species) should be marked with a durable tag, and
information on each plant species' origin (nursery,
transplant, etc.) and size should be supplied. Other
initial site conditions that aid in site evaluation are
soil bulk density, organic content, particle-size
distributions, redox, pH, nitrogen, and interstitial
salinities across the site. Although biotic compo-
sition of sediments would be informative, assessing


Crewz and Lewis, 1991







Page 57


success in this category requires that standards exist
against which site qualities can be evaluated; these
standards have not been compiled for natural marine
wetlands in Florida.
Especially useful to regulatory agency personnel
are color aerial and ground-level photographs depicting
important characteristics of the wetlands creation
effort. Ground-level photographs should be taken from
fixed locations established by regulatory agency
personnel so that site development can be compared to
that of earlier monitoring visits. Because many plant
species, especially grasses, orient predominantly
perpendicular to the path of the sun, some photographs
should be taken from directions perpendicular to each
other to avoid the impression of a denser plant cover
than actually exists.
A statistically sound sampling program that
employs accepted scientific techniques should be used
to measure pertinent site characteristics at each
monitoring visit. The standard vegetative variables
usually estimated are percentage cover by species,
density (where applicable), survival, and colonization.
Additional variables estimated for trees are growth
measured as diameter at breast height (DBH), height
increases, and crown spread. The most informative
measurement is probably percentage cover by species.
Percentage-cover data, combined with site drawings
showing major plant distributions, provide much of the
information needed to quickly evaluate plant survival
and growth. Plant density can often be misleading,
especially for clonal plants such as smooth cordgrass
or for plants that are not easily itemized such as
mat-forming grasses; for these species, biomass esti-
mates may be informative. Biomass studies are
destructive if enough samples are taken to properly


Crewz and Lewis, 1991







Crewz and Lewis. 1991


evaluate standing crops. Although it probably under-
estimates plant productivity, biomass sampling is
useful for research comparisons of planting techniques.
Height increases for mangroves are probably valid only
through the first several years; after that, canopy
coverage is of greater value.
When a site has been specifically constructed to
provide animal habitat, animal presence at the site
should be recorded over at least a 24-hour period at
each monitoring visit. For some species, different
life-history stages must be sampled (e.g., larval,
juvenile, and adult fish); season, target species, and
wetlands type will determine the proper sampling gear.
Quantifying the presence of animal species is an essen-
tial first step in evaluating the functional efficacy
of wetlands creation methods. However, comparing the
functional equivalency of a created site to that of a
natural site requires more than simple observation of
faunal occurrence. The mere presence of animals at a
created site does not necessarily indicate that the
organisms are benefiting similarly to what might be
obtained from a natural site. Habitat loss in the
region may have forced animal species to congregate in
the created site, but the site may not be satisfying
their nutritional needs, especially in regard to repro-
duction energetic. Long-term trophic analyses are
needed to assess the efficiency of energy transfers to
specific faunal groups in created marine wetlands. For
example, Moy and Levin (1991) assessed the relationship
between sediment structure, infaunal composition, and
Fundulus heteroclitus use in a manmade marsh and two
natural marshes. They concluded that, based on lower
Fundulus abundance in the planted marsh, the man-made


Paae 58







Crewz and Lewis, 1991 Page 59


marsh and the natural marshes were "functionally
distinct" after three years, despite some shared
structural characteristics.
Measuring a broad range of variables before and
after wetlands are constructed is economically
demanding and may seem unreasonable. Much of the
justification for the widespread application of miti-
gation, however, is that each site is part of a larger
"experiment" that will eventually determine how best to
use mitigation to offset wetlands losses. Most moni-
toring of mitigation projects, nevertheless, produces
little more than anecdotal information. Even when
comprehensive data are obtained in monitoring programs,
communicating the information to others is often a low
priority of the data collector. One major obstacle we
faced at the beginning of our study was obtaining reli-
able site-creation data that could be used to select
sites. Record-keeping and communication have sub-
stantially improved at all levels since our initial
survey, but records are still widely dispersed among
different agencies, businesses, and locations; data
collection is still nonstandardized, making site and
technique comparisons difficult. As long as mitigation
is justified as "experimental," rigorous monitoring
standards must be developed and required. Also, the
data must be made available so that complex biotic and
abiotic interactions in developing marine wetlands can
be assessed adequately. Data availability could be
achieved by centralizing data in regional depositories
that employ state-of-the-art information-retrieval
systems.
To improve the probability of successful plant
establishment and of development of mature, functional
wetlands, the length of the monitoring program and the
frequency of site visits must be adequate. Histor-







Page 60


ically, the overall length of the monitoring program
has been approximately two to three years, up to five
years for some habitats. Monitoring programs can be
shorter for herbaceous plantings (see Figure 12 for an
example), but longer programs should be required for
monitoring forested wetlands; certainly, five years
should be the absolute minimum for mangrove plantings.
Many years may pass before environmental qualities of
young, vulnerable created wetlands interact with random
events (e.g., hurricanes, insect/pathogen presence)
that may cause severe damage. Monitoring programs of
three to five years may be adequate for assessing
short-term survival of installed plants, but longer
monitoring programs, coupled with remedial actions,
will improve the likelihood that the site matures
properly and persists through younger stages. The
original condition of the destroyed wetlands could be
used to determine the length of the monitoring program
for mitigation projects. Mature, natural mangrove
forests are greater than 25 years of age, depending on
hurricane frequency; mitigation for their destruction
may require an extended monitoring program (10-25
years) to ensure an equitable habitat trade-off based
on vegetation characteristics. As monitoring programs
are extended to deal with long-term wetlands matu-
ration, the chances that extreme natural events might
affect created wetlands increase. Exemptions from
responsibility for certain types of natural damage may
be necessary to protect the permitted. Exemptions
should not be allowed if the regulatory agency can
justify the created wetland's increased vulnerability
compared to adjacent, undamaged, mature wetlands of the
same type.
The periodicity recommended for monitoring has
usually been quarterly and biannual site visits.


Crewz and Lewis, 1991







Crewz and L 1991 Pa-e 61


Monitoring visits should be made more often at the
beginning of the project but can be less frequent as
the site ages (Figure 12). Initially, two-week inter-
vals may be needed to assure that immediate problems
are resolved. Quarterly visits should be acceptable
after the first three months if the site has not
required extensive reworking. Any anomalies at the site
should be immediately reported in writing to the
regulatory agency so that remedial actions can be
authorized and implemented. Biannual visits should be
adequate in the second and third years. After three
years, annual visits could be made to ascertain if
severe natural events or human activities have made
encroachments. A final report should be produced by
the monitoring firm at the end of the monitoring
program, and regulatory agency personnel should visit
the site to determine the success of vegetation
establishment in accord with permit objectives and site
data in the final report.
Remedial actions may be needed to correct obvious
problems if a site is not developing properly. Under-
staffing, personnel turnover, and inexperienced staff
in regulatory agencies have resulted in many wetlands
creation projects that, because of the lack of timely
remedial actions, could not be deemed successful.
Frequently, monitoring reports--if they are submitted
at all--are not checked to determine if the site needs
remedial treatment. Timely and ecologically sound
action must be taken by the responsible regulatory
agency, or site-specific problems can become more
difficult to repair later. Some site problems can be
easily resolved (e.g., poor plant material or
drainage), but other problems may require substantial


Crewz and TPwin. ~991


Pae 61> C











1.0 1.5 2.0 2.5 3.0



-----------
----------..------------..-------------------------

4.0 5.0 6.0 9.0 12.0




-----------------------------------------------------
HHN---n---


18.0 24.0 30.0 36.0

fi-n-n-n


VERTICAL WHITE LINE


REPRESENT SITE VISITS


MONTH0--AS-BUILT PLANS AND REPORT
(SEE TEXT)
MONTH 0.5-NARRATIVE / REMEDIAL
ACTIONS
MONTH 1.0-MONITOR (% SURVIVAL BY
SPECIES, PHOTOS) I REMEDIAL ACTIONS

MONTH 1.5-NARRATIVE I REMEDIAL
ACTIONS
MONTH .0-NARRATIVE I PHOTOS I
REMEDIAL ACTIONS
MONTH 2.5-NARRATIVE/ REMEDIAL
ACTIONS
MONTH 3.0-MONITOR (% SURVIVAL BY
SPECIES, % COVER BY SPECIES,
VOLUNTEERS BY SPECIES, PHOTOS) /
REMEDIAL ACTIONS
MONTH 4.0 (IF SITE HAS REQUIRED
REWORKING)-NARRATIVE / REMEDIAL
ACTIONS

MONTH 5.0 (IF SITE HAS REQUIRED
REWORKING)-NARRATIVE / REMEDIAL
ACTIONS


MONTH6.0-MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) /
REMEDIAL ACTIONS

MONTH 9.0-MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) /
REMEDIAL ACTIONS

MONTH 12.0--MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) I
REMEDIAL ACTIONS

MONTH 18.0-MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) /
REMEDIAL ACTIONS

MONTH 24.0--MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) I
REMEDIAL ACTIONS

MONTH 30.0-MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) I
REMEDIAL ACTIONS

MONTH 36.0-MONITOR (% COVER BY
SPECIES, SITE MAPS, PHOTOS) /
REMEDIAL ACTIONS


FIGURE 12. SUGGESTED SCHEDULE FOR MONITORING A SMOOTH
CORDGRASS MARSH CREATION PROJECT. AFTER THREE
YEARS, ANNUAL VISITS SHOULD BE MADE TO ASSESS SITE
STATUS AND TRENDS,


MONTH 0






MONTH


MONTH
I


ES







Crewzand Lewis, 1991 Paae 63


efforts to correct. For example, elevations may be too
high, or the site may be too enclosed to flush
properly.
Regulatory agencies may require the permitted to
do additional work offsite if repeated remedial actions
fail; these possibilities should be specified as
options in the permit. A site may be deemed of value
in regard to other qualities, however, and regulatory
agencies may choose to disregard species requirements
and opt to accept the site as is. This option is
feasible if legal requirements have not mandated a
specific type of wetlands creation. Thus, wetlands
creation could be evaluated on a regional basis, with
the possibility that out-of-kind projects, which offset
losses of other wetlands types, may be authorized.
These decisions often require value judgements that are
arbitrary at best. By assessing wetlands creation
trade-offs regionally, however, regulatory agencies
could balance broad-scale biodiversity losses more
effectively. Biodiversity losses are of great national
concern, and methods for maintaining biodiversity
losses in Florida are being addressed under the
Preservation-2000 and Conservation-2000 programs
proposed by the Governor's office.
A properly designed and implemented monitoring
program should protect created wetlands from economic
development over the short term. Long-term protection
for created wetlands is less of a sure thing. Once the
regulatory agency deems the created wetlands success-
ful, the permitted is relieved of responsibility, and
the site may once again become vulnerable to permit-
table activities. Conservation easements that restrict
future destruction of wetlands are often filed with
county governments. Conservation easements for
properly permitted projects may be an effective way to


Crewz and Lewis, 1991


Pace 63







..Cr.wz and Lewis. 1991. -6


preserve valuable wetlands. The only option for long-
term wetlands protection from illegal damage is
enforcement that has enough teeth to discourage others
from damaging created and natural wetlands.


Summary

To summarize, the primary causes of vegetative failure
in the sites we surveyed resulted from, in order of
decreasing occurrence, improper planting elevations,
improper slopes and site drainage, inferior substrates,
expedient planting techniques, site location and
structure problems, failure to restrict human access,
and use of inferior plant materials. Lack of valid
follow-up programs also contributed to site failures.
Some characteristics of a hypothetical unsuccessful
saltmarsh creation project are shown in Figure 13, and
those of a successful project are shown in Figure 14.
Many actions can be taken that ensure a higher
probability of planting success in marine wetlands
creation projects. Conservative recommendations for
increasing planting success, based on the above cate-
gories of site problems, are presented below. Because
of the moderating influences of interacting variables
that are site specific, alternative approaches may be
useful at certain sites. Experienced site planners
must modify these generalities to accommodate site-
specific idiosyncrasies.


1) Elevation Plant mangroves at approximately
mean high water or at elevations determined from
natural distributions of juvenile or young-adult plants
adjacent to the site. In rocky substrates in the
Florida Keys, mangroves should be planted well below
mean high water; marl and peat substrates allow


I


~ypWZ ~n~3 T.nwis. 1991


Paae 64












ENCLOSED SITE (EARTH BERM)
NOT PROTECTED FROM HUMANS
IMPROPER CHANNEL DESIGN
,e, IMPROPER ELEVATIONS
*' NO VEGETATED BUFFER
,f POLLUTANT RUNOFF
SPOOR SUBSTRATES
HARDENED SHORE
SLOPE EROSION
EXOTIC PLANTS
S, STEEP SLOPES
PONDING


FIGURE 13. CHARACTERISTICS OF A HYPOTHETICAL UNSUCCESSFUL
SALTMARSH CREATION PROJECT IN FLORIDA,














ROCK BERM FOR WAVE PROTECTION
PROPER CHANNEL DESIGN
PROTECTED FROM HUMANS
NO POLLUTANT RUNOFF
NO SHORE HARDENING
",.. PROPER ELEVATIONS
'"* PROPER SUBSTRATES
VEGETATED BUFFER
NO EXOTIC PLANTS
,.. GENTLE SLOPES
('uit, '""'. STABLE SLOPES
.. .... NO PONDING


FIGURE 14. CHARACTERISTICS OF A HYPOTHETICAL SUCCESSFUL
SALTMARSH CREATION PROJECT IN FLORIDA,


I I '' I I '' I II







Crews and Lewis 1991


planting closer to mean high water. Plant smooth
cordgrass below mean high water down to approximately
+0.2 m NGVD. Plant needle rush from mean high water to
the average level reached by spring tides (i.e., in the
high marsh). Other species--such as saltgrass, marsh-
hay, sea ox-eye daisies (Borrichia spp.), beach-elder
(Iva imbricata Walt.)--can be planted in the high
marsh, as well. Tidal variation at each site can alter
planting elevation. An easily accessible benchmark
should be established at all sites so that elevation
changes can be monitored.
2) Slope Gentle slopes, preferably less than 10
percent, should be established within the optimal ele-
vation ranges of the species to be planted. Slopes
should be even and directed toward predominant tidal
sources (e.g., channels, creeks, bays, etc.). Gentle
slopes in marginal, vegetated uplands are important
buffers for wetlands sites.
3) Drainage Ditches, swales, and channels should
be incorporated into large wetlands designs to aid
drainage. Ponded areas should be connected to the
drainage channels to eliminate large areas of standing
water. Drainage channels should retain water at low
tide but should not be much deeper (10 25 cm) than
the access channel (if applicable) to the site.
4) Substrates Rock and clay layers should be
avoided when choosing potential sites; coring can
define predominant strata. Substrates should be of a
consistency to provide good support to installed
plants. In the Florida Keys, marl and limerock sub-
strates require special actions related to plant
culture, planting density, elevations, etc. (see other
sections).
5) Fertilization Fertilizers are probably not
necessary except where fast top growth is desirable for


,Da -g97


Paerr 67







CrA gan e9


smooth cordgrass. Light fertilization may be useful in
mangrove plantings in the Florida Keys. If fertilizer
is added, separate time-release fertilizer pellets for
nitrogen and phosphorus should be added to the planting
hole in a 3:1 ratio (N:P).
6) Site Design Sites should be created to maxi-
mize contact with the marine system. If an enclosed
site with access channels is desired, the size and
orientation of the entrances should maximize flushing
without exposing the site to prevailing winds and
extreme wave energy. Open sites should have fetches
less than one mile or should be protected by artificial
structures such as riprap berms. Sites exposed to long
fetches should be planted with smooth cordgrass rather
than mangroves. Enclosed sites should not be designed
to accept major stormwater drainage from lawns and
roads.
7) Human Access Barriers to human intrusion--
such as fences, water bodies, and buffer zones--should
be used wherever possible. Densely vegetated buffer
zones around the site are especially useful for dis-
couraging trespassers.
8) Plant Quality Plants should be protected from
sun and desiccation during transit to the site. Plants
should be raised under nursery conditions similar to
the conditions at the planting site. In the Florida
Keys, mangroves should be cultured in a marl substrate,
not solely in peat. Plants destined for saline sites
should be raised under a constant salinity regime, not
just acclimatized a few weeks prior to planting. Fer-
tilization should be kept to a minimum under nursery
conditions. Root-bound potted plants should be avoided
because of slow establishment.
Although restrictions on transplanting marine
wetlands plants exist, properly transplanted smooth


Crewz and Lewis 1991


Pa e 68







Crewz and Lewis. 1991


cordgrass frequently exhibits better survival than
nursery-grown plants. If use of donor sites is per-
mitted, damage to them should be kept to a minimum.
Mangroves should not be transplanted, except under
special situations determined by the appropriate
permitting agencies. Red mangrove propagules can be
directly planted successfully in proper sites. One- to
two-year-old mangrove seedlings should be used rather
than propagules when rapid coverage is needed. Man-
groves probably have better survival and growth when
planted in existing smooth cordgrass stands.
9) Density One-meter centers is an acceptable
density for smooth cordgrass plantings in low-energy
environments, but densities should be greater in
relatively high-energy areas. Planting densities for
mangroves should always be greater than for smooth
cordgrass, especially in the Keys. If red mangrove
propagules are installed, the density should be 25 cm
on center, and for one-year-old seedlings, no more than
50 cm on center. Densities for restoration projects
can be lower than for mitigation projects. Mangroves
can be established on more energetic shorelines by
first establishing a dense cover of smooth cordgrass
and then interplanting with mangroves.
10) Monitoring Efficient monitoring programs are
an essential component of successful plant estab-
lishment. Monitoring should begin within two weeks of
site planting and should be frequent through the first
six months. Quarterly sampling and eventually biannual
or yearly visits can be made once the site has become
well established. Written reports and photographs
should be submitted to the regulatory agency at time-
zero and immediately if problems are observed. Moni-
toring programs should last at least five years for
mangrove projects, but three years may be adequate for


Paae 69







Crewz and Lewis. 1991 Pacr~ 70


assessing short-term survival of herbaceous plantings.
The most informative variable is percentage cover by
species, and it should be combined with a site drawing
showing plant distributions.


Concluding Remarks

The sites surveyed in this investigation were a his-
torical sampling and, as such, do not necessarily
reflect vegetative success of wetlands creation using
current technology. Decisions regarding the predict-
ability of wetlands creation efforts should be based on
current abilities, not historical attempts that were
principally trial-and-error "experiments." None-
theless, recent surveys of additional sites have
revealed that, despite so-called current technical
know-how, the exact same mistakes that were made at
older sites are still being made in many newer creation
projects.
Current misapplications of marine wetlands
creation technology result principally from a lack of
comprehensive knowledge about site-specific idio-
syncrasies of natural marine wetlands. This problem is
compounded by a lack of sufficient expertise in many
business and regulatory agency personnel, who often
base their wetlands creation philosophies on unsub-
stantiated traditional methodologies, regardless of
their ecological value. Few qualifications are
required for wetlands creation "specialists," and many
agencies and businesses often lack personnel with
adequate formal and practical botanical, ecological,
landscape design, and engineering expertise. The
expertise to provide quality plants, to create and
repair habitats, and to assess the quality of the
planting effort must be ensured through formal training


Crewz and Lewis. 1991


Pafe 70







..Cr.wz and Lewis. 1991. -6


preserve valuable wetlands. The only option for long-
term wetlands protection from illegal damage is
enforcement that has enough teeth to discourage others
from damaging created and natural wetlands.


Summary

To summarize, the primary causes of vegetative failure
in the sites we surveyed resulted from, in order of
decreasing occurrence, improper planting elevations,
improper slopes and site drainage, inferior substrates,
expedient planting techniques, site location and
structure problems, failure to restrict human access,
and use of inferior plant materials. Lack of valid
follow-up programs also contributed to site failures.
Some characteristics of a hypothetical unsuccessful
saltmarsh creation project are shown in Figure 13, and
those of a successful project are shown in Figure 14.
Many actions can be taken that ensure a higher
probability of planting success in marine wetlands
creation projects. Conservative recommendations for
increasing planting success, based on the above cate-
gories of site problems, are presented below. Because
of the moderating influences of interacting variables
that are site specific, alternative approaches may be
useful at certain sites. Experienced site planners
must modify these generalities to accommodate site-
specific idiosyncrasies.


1) Elevation Plant mangroves at approximately
mean high water or at elevations determined from
natural distributions of juvenile or young-adult plants
adjacent to the site. In rocky substrates in the
Florida Keys, mangroves should be planted well below
mean high water; marl and peat substrates allow


I


~ypWZ ~n~3 T.nwis. 1991


Paae 64







Crewz and Lewis. 1991 Paae 71


programs for regulatory agency personnel and business
persons involved in wetlands creation. Training
programs and certification procedures similar to those
for professional engineers are needed to educate not
only habitat engineers, who will be able to certify
proper site designs, but also regulatory personnel, who
will be able to evaluate site quality and monitoring
reports effectively.
Our study has touched on some of the horticultural
aspects germane to marine wetlands creation success.
However, one person's having the horticultural ability
to establish plants at one site does not provide an
adequate measure of whether marine wetlands in general
can be created predictably. Without the guarantee of a
high predictability for creating ecologically sound
wetlands, mitigation trade-offs cannot be viewed as an
acceptable alternative to preserving valuable natural
wetlands. A conservative approach to wetlands destruc-
tion should be adopted until a more substantial base of
knowledge is developed for critical ecosystem functions
in natural wetlands.
The primary aim in protecting marine ecosystem
quality should be to minimize the removal and degra-
dation--e.g., by seawalls, pavement, and chronic
pollution--of wetlands involved in critical marine
ecosystem processes. At every opportunity, wetlands
lost to these impacts should be returned to a condition
that allows them to undergo ecosystem-level changes.
Although the types of marine wetlands (e.g., mudflat,
marsh, or mangrove) that are created is important on a
local scale, the higher priority is to ensure that
.marine wetlands maintain the potential for change and
maturation, thereby bringing diverse habitats into a
"natural" balance.


Crewz and Lewis. 1991


Paae 71







Crewz and Lewis. 1991 Pacr~ 70


assessing short-term survival of herbaceous plantings.
The most informative variable is percentage cover by
species, and it should be combined with a site drawing
showing plant distributions.


Concluding Remarks

The sites surveyed in this investigation were a his-
torical sampling and, as such, do not necessarily
reflect vegetative success of wetlands creation using
current technology. Decisions regarding the predict-
ability of wetlands creation efforts should be based on
current abilities, not historical attempts that were
principally trial-and-error "experiments." None-
theless, recent surveys of additional sites have
revealed that, despite so-called current technical
know-how, the exact same mistakes that were made at
older sites are still being made in many newer creation
projects.
Current misapplications of marine wetlands
creation technology result principally from a lack of
comprehensive knowledge about site-specific idio-
syncrasies of natural marine wetlands. This problem is
compounded by a lack of sufficient expertise in many
business and regulatory agency personnel, who often
base their wetlands creation philosophies on unsub-
stantiated traditional methodologies, regardless of
their ecological value. Few qualifications are
required for wetlands creation "specialists," and many
agencies and businesses often lack personnel with
adequate formal and practical botanical, ecological,
landscape design, and engineering expertise. The
expertise to provide quality plants, to create and
repair habitats, and to assess the quality of the
planting effort must be ensured through formal training


Crewz and Lewis. 1991


Pafe 70







Page 72


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and J. R. Thomas. 1980. Planting of red
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Hardaway, C. S. 1986. Marsh grass reestablishment in
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and K. C. Haines. 1981. Large-scale
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(ed.), Proc. Seventh Ann. Conf. Rest. Creation
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Lindeman, W. and J. Wilt, Jr. 1989. Effectiveness of
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Tampa, FL.


Crpew and Lewis. 1991


Paae 76


-~ I


































APPENDIX A


FLORIDA KEYS SITE DESCRIPTIONS









Coral Shores Estates The Coral Shores Estates site
resulted from illegal dredge-and-fill in a former
mangrove area. Canals that had been dug were refilled
with the scrapedown material, which was primarily marl
mud. Red mangrove seedlings (one year old?) were
planted around the margin of the scrapedown in a strip
approximately eight meters wide; they were completely
exposed at low tide. The total scrapedown was not
surveyed because of the young age of the site. The
remainder of the site had shallow, standing water in
spots at low tide and was unvegetated. Adjacent
mangroves occurred at elevations (+0.21 to +0.27 m
NGVD) similar to most of the elevations in the planted
area. Plants installed at lower elevations (+0.01 to
+0.14 m) may have had slightly better survival. Some
plants used at this site were cultured two-to-a-pot and
then ripped apart for planting; this improper handling
prior to installation probably caused the death of some
plants. Plants that had been grown one-to-a-pot had
almost 100 percent survival. Another problem encoun-
tered at this site was that roots of plants cultured in
peat tended to be restricted to the peatball after
planting, resulting in a dwarfing or bonsai effect when
installed in marl mud. Even though the planting was
less than one year old, some root growth into the sur-
rounding medium should have occurred within that time.
One characteristic, which was also common to all man-
grove plantings surveyed in this study, was that the
planting density was too low (one meter O.C.) to result
in effective coverage within a reasonable time frame.
Unlike the rapid coverage achieved by rhizomatous
grasses and other herbaceous plants, mangroves are
slower growing, especially in the Keys, and do not
produce equivalent coverage as rapidly.

Locale: Little Torch Key; Monroe County
Latitude/longitude: 24*41'18"N / 81"23'54"W
Permit numbers: FDER None; ACOE 77-4528 (enforcement
case no.)
Age: <1 yr
Size: 0.2 ha planted (3.2 ha total scrapedown)
Species present: Rhizophora mangle
Status: Failure


Cross Street At the Cross Street site, illegal fill
material was removed in an attempt to reestablish
elevations conducive to natural colonization by propa-
gules produced by surrounding mangroves; no planting
was attempted. The site was roughly rectangular in
shape and sloped gradually from the higher elevations
near Cross Street to the lower elevations at the back


A-1










of the site. A concrete culvert under a lateral road
connected the site at the low end to the marine system.
The higher elevations near the road were exposed lime-
rock, but the majority of the site was composed of marl
mud. Even at low tide, standing water was present in
the lower elevations of the site; the presence of
widgeon-grass (Ruppia maritima L.) suggests that the
standing water may have been at least seasonal. Most
plant colonization occurred in the cracks and shallow
depressions of the exposed limerock. Adjacent
undisturbed mangrove elevations were higher than most
of the scrapedown area. At this site, better plant
colonization occurred in areas that were at approxi-
mately the same elevations as adjacent mangroves or a
little higher.
Vegetation colonization was impaired by the low
elevations in most of the site. Standing water can
become too warm in the summer, impairing survival of
mangroves that may have colonized in the previous fall.
In another part of this site, the exposed limerock was
a poor substrate for colonization. Covering the lime-
rock with a thin veneer of marl would create a more
even substrate for colonization by grasses and forbs.
Vegetation colonization could be enhanced by filling
the site to the level of surrounding mangroves and by
dispersing propagules.

Locale: Stock Island; Monroe County
Latitude/longitude: 24036'06"N / 8144'42"W
Permit numbers: FDER None; ACOE 81A-37-071
Age: 2 yrs
Size: 0.70 ha
Species present: Avicennia germinans, Laguncularia
racemosa, Ruppia maritima, Salicornia
bigelowii
Status: Failure
-------------------------------------------

Florida Keys Aqueduct Authority The Florida Keys
Aqueduct Authority restoration was an attempt to
partially revegetate backfill following installation of
a large water supply line. The disturbed mangrove area
was approximately ten meters wide and paralleled U.S.
Highway A1A for several miles. An unknown number and
arrangement of mangrove propagules and smooth cordgrass
plugs were planted along an unknown extent of the site.
The survey began at the first accessible area from the
north along A1A and extended for a predetermined
distance of ten sample points at regular interplot
distances (total length approximately one kilometer).
Substrates ranged from soft mud to an occasional
rocky outcrop. The predominant plant species at this


A-2










site were smooth cordgrass and black mangrove. The
range of elevations colonized by black mangroves was
slightly higher than that for smooth cordgrass, but
these species overlapped through most elevations. The
greatest overall densities occurred within a range of
approximately 0.09 m in the middle elevations. The
cable roots of black mangrove had trouble penetrating
the substrate and were arched like the prop roots of
red mangrove, probably indicating a hard surface just
under the mud. Standing water, present along much of
the length of the survey, was very warm. Undisturbed,
adjacent mangroves were approximately three meters
tall, and the topography under them was even, unlike in
the restored area where substrates varied in elevation.
Vegetation was found mostly on the higher elevations.
Variable elevations, possibly due to uneven settling of
heterogeneous fill material, resulted in poor drainage
from some areas. The back-fill material may have been
too coarse--that is, composed of large boulders--to
allow proper root penetration by mangroves.

Locale: Key Largo; Monroe County
Latitude/longitude: 25*06'39"N / 80*24'52"W
Permit numbers: FDER 13- and 44-28299; ACOE 80M-0276
Age: 5-6 yrs
Size: 3.5 ha
Species present: Avicennia germinans, Conocarpus
erectus, Fimbristvlis castanea,
Laqun cularia racemosa, Rhizophora
mangle, Spartina alterniflora
Status: Mixed success


Florida Keys Land Trust, Inc. The Florida Keys Land
Trust, Inc. site consisted of illegal road fill that
was removed to restore natural sheet flow to the scrub
mangrove area; no planting was attempted. The most
landward portion of the site had higher elevations that
descended to a muddy depression colonized by black
mangroves. The topography on either side of the
scrape-down rose to a scrub mangrove/high-marsh plant
association that was rooted in a veneer of marl mud
overlying limerock; the scrapedown exposed the under-
lying rock. The rock gave way to gradually decreasing
elevations of marl mud covered with standing water. At
the seaward end, standing water was as much as 0.3 m
deep at low tide. Colonization in the marl-mud area
was limited to a few scattered red mangroves (not in
our sample plots) and black mangrove seedlings, except
in the low area landward of the rock zone. All of the
vegetation was in the upper 27 percent of the eleva-
tions, despite most of this area being rock. Rhizoma-


A-3










tous and stoloniferous grasses and forbs predominated
on the rock elevations. In the adjacent undisturbed
area, larger red mangrove plants had developing propa-
gules that may colonize the site at a later date. All
colonizing plants at this site were depauperate.
Although the scrapedown of the road improved tidal
sheet flow in this area, vegetation establishment at
this site was reduced because much of the site was
graded too low and therefore did not drain properly.
Also, drainage was further impeded by a mature mangrove
fringe, which served as a berm. This fringe could
block propagule transport into the site. Another
problem resulted from the lack of substrates appro-
priate for colonization. When the site was scraped
down, the veneer of marl was completely removed down to
limerock, which impeded colonization by shallowly
rooted grasses and forbs. Vegetation establishment at
this site could be improved by filling the low areas to
a level equal to the surrounding areas; breaching the
mangrove fringe with a shallow, broad creek; planting
the soft mud with red mangroves; and covering the rock
with two to three centimeters of marl. Mangrove colon-
ization failure at this site, even after four years,
highlights the need to provide appropriate elevations
and propagules for proper vegetation establishment to
occur.

Locale: Big Pine Key; Monroe County
Latitude/longitude: 2442'45"N / 81022'10"W
Permit numbers: FDER None; ACOE None
Age: 4 yrs
Size: 0.2 ha
Species present: Avicennia germinans, Batis maritima,
Borrichia arborescens, Monanthochloe
littoralis, Salicornia bigelowii, S.
virginica, Sporobolus virginicus
Status: Failure
------------------------------------------

Hammer Point The Hammer Point site was a scrapedown
of illegal fill that had been placed between a series
of canals to extend a housing project. The canals
divided the restoration site into four separate areas.
The coral rock substrate was of even elevation, and at
low tide, the lower elevations were under approximately
0.2 m of water; the higher elevations had some standing
water but were probably exposed at the lowest tides.
The substrate was so hard that the red mangroves had to
be hosed into the substrate. Most of the red mangroves
were in the sapling class (>0.3 m); however, at instal-
lation they were already over 0.3 m tall. Because
elevations designed for this project were low, a green


A-4










alga (Batophora sp.?) carpeted the substrate. The
presence of shoal-grass (Halodule wrightii Aschers.)
also indicated that most of the site remained per-
manently inundated. Survival of planted red mangroves
at this site can be attributed, in part, to good water
quality and to lower planting elevations in the hard
substrate. However, the rate of plant growth was slow,
possibly because of the poor substrate. The major
growth impairment was probably due to constriction of
the mangrove roots within the peat football, which
caused a dwarfing or bonsai effect. Even after two
years, the planted mangroves could easily be lifted
from the substrate, and the original shape of the
football could be observed.

Locale: Key Largo; Monroe County
Latitude/longitude: 25*01'24"N / 80030'45"W
Permit numbers: FDER None; ACOE 71-1176 (enforcement
case no.)
Age: 2 yrs
Size: 1.0 ha
Species present: Halodule wrightii, Rhizophora mangle
Status: Failure
------------------------------------------------

Loggerhead Lane The Loggerhead Lane site was a
scrapedown of illegal fill that had been placed in
seasonally flooded wetlands. Adjacent vegetation
indicated the area was probably sparsely vegetated with
mangroves before filling occurred. The scrapedown
resulted in uneven topography, covered mostly with
standing water approximately 0.3 m deep. Supposedly,
black mangroves were planted along the margin, but we
observed only a few volunteer seedlings. The dominant
species at lower elevations was spike-rush (Eleocharis
cellulosa Torr.), which usually occurs in low salin-
ities. Elevations of the adjacent mangroves were
higher than the substrate elevations in the scrapedown
area. Increasing the substrate elevations slightly may
encourage reestablishment of saline-adapted vegetation.

Locale: Sugarloaf Key; Monroe County
Latitude/longitude: 24040'10"N / 8122'10"W
Permit numbers: FDER None; ACOE 82W-37-032 (enforcement
case no.)
Age: 4 yrs
Size: 0.4 ha
Species present: Aster sp., Avicennia germinans, Bacopa
monnieri, Eleocharis cellulosa, E.
geniculata
Status: Failure


A-5










Rock Harbor The Rock Harbor site was mitigation
intended to offset canal construction to gain water
access to a nearby development. Most fill material was
removed to elevations approximating mean low water, and
red mangroves were installed. The rocky marl substrate
was uneven in topography. The higher elevations were
exposed limerock and were littered with trash. Exten-
sive areas of standing water were filled with shoal-
grass, indicating that flooded conditions were
permanent.
The planted red mangroves were spindly, and the
lower two-thirds of each stem was covered with green
algae. Most surviving mangroves occurred in the upper
half of the substrate elevations. Survival of the
planted red mangroves at lower elevations was due, in
part, to good water quality. Low scrapedown elevations
caused mangroves to be spindly; these planted mangroves
had only a few leaves at the top of a meter-long stem.
Adjacent mangrove areas were higher and had a dense
fringe of robust red mangrove seedlings. The natural
fringe was approximately one meter higher than the
lowest areas of the scrapedown.

Locale: Key Largo; Monroe County
Latitude/longitude: 25004'56"N / 80026'51"W
Permit numbers: FDER 44-34296; ACOE 80J-1758
Age: 3 yrs
Size: 1.3 ha
Species present: Avicennia germinans, Halodule
wrightii, Laquncularia racemosa,
Rhizophora mangle, Salicornia
bigelowii
Status: Failure


Sexton Cove At the Sexton Cove site, an attempt was
made to plant red mangroves following scrapedown of
illegal fill and backfilling of canals. Sea-grass was
installed in low areas of the cove but was not included
in this survey. The substrate was hard-packed, crushed
limestone rubble. The topography of the site was even,
with the lowest region being in the middle of its long
dimension (parallel to the adjacent road). Planting
holes for the mangroves were apparently created with an
auger. The few red mangroves that survived were
depauperate.
All colonizing plants were found in the upper half
of the elevations. At low tide, the planted area was
completely dry, except for water trapped in the auger
holes. High summer temperatures apparently heated the
water that was retained by the auger holes at low tide,
damaging the mangrove seedlings. As at other sites in


A-6










the Keys, the hard, low-nutrient substrate created a
dwarfing or bonsai effect on the planted mangrove
seedlings; roots never left the peatball. Unlike most
of the other Keys sites surveyed in this project,
overall elevations may have been too high for good
mangrove growth. In hard rock substrates, survival of
mangrove seedlings may depend on constant flooding
during the hottest months.

Locale: Key Largo; Monroe County
Latitude/longitude: 25*10'09"N / 8023'02"W
Permit numbers: FDER None; ACOE 74-1067-CIV-SMA
(consent agreement case no.)


Age: 2 yrs
Size: 0.2 ha
Species present:






Status: Failure


Avicennia qerminans, Baccharis sp.,
Batis maritima, Blutaparon
vermiculare, Casuarina sp.,
Conocarpus erectus, Heliotropium
currassavicum, Laquncularia racemosa,
Rhizophora mangle, Sporobolus
domingensis


A-7


































APPENDIX B



ATLANTIC COAST SITE DESCRIPTIONS







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