proposed stormwater & mitigation wetland plan
DESCRIPTION
Ithaca College Proposed Sports Complex Restoration Ecology class project Fall 2008TRANSCRIPT
Proposed Stormwater Management & Mitigation Wetland Plan Ithaca College
Propose omplex d Sports C
Fall 2008
2
Project Contributors
This report is the product of Tom Whitlow’s Restoration Ecology course offered
through the Cornell Horticulture Department. The class is composed of landscape
architecture, environmental engineering, urban planning, and natural resources students,
oth undergraduate and graduate. Restoration Ecology is a one semester, 5‐credit course. b
Professor Tom Whitlow
Teaching Assistant Fred Cowett
Kate Bentsen
Maureen Bolton
Hannah Carlson
I nga Conti‐Jerpe
Matthew Doro
Eden Gallanter
Karli Gallow
Adam Ganser
Ying‐Tuan Hsu
Jason Johnson
Ch il ristopher Ke
Shichun Ni
Lee M. Pouliot
Zac Rood
Peter Sigrist
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Table of Contents
I. Introduction
II. Methods & Materials
III. rest Ithaca College Slope Fo
IV. Ithaca College Hilltop:
a. wamp Swamp White Oak S
b. Red Pine Plantation
V. Ithaca C t: ollege Parking Lo
a. Wetland Corridor
b. Downstream Corridor
VI. nagement Plan Proposed Stormwater Ma
VII. n RPM Old Field in Dryde
VIII. Special Considerations
a. Amphibian Breeding Habitat
mendations b. Amphibian Habitat Recom
IX. Recommendations & Conclusions
4
Introduction
This report is in response to the proposed sports complex at Ithaca College, which will
destroy several acres of wetland, necessitating the creation of mitigation wetlands. The
Army Corps of Engineers has stipulated that, in accordance with the Clean Water Act, three
acres of wetland shall be created for every one acre destroyed by development. We have
met with Ron LeCain, Rick Couture, and Jason Hamilton of Ithaca College in order to assess
and respond to their needs and agenda.
Our project parameters include research and data collection for the purpose of
iden structed wetlands in the following areas: tifying an appropriate site for con
1. The Ithaca College slope forest
mmunities 2. The Ithaca College hilltop swamp and red pine co
3. The Ithaca College parking lot wetland corridor
4. The old field in Dryden – adjacent to the RPM nursery
5. Multiple wetlands at the Ithaca College sports arena site & associated down slope
stream
6. Bull Pasture Pond
There are three possible sites for the proposed wetlands; the Ithaca College slope
forest, the hilltop communities at Ithaca College, and the old field site in Dryden. The other
sites we studied were for reference and research purposes. All data was gathered with the
intent to determine where a new wetland could be most useful for the community, water
quality issues, to threatened species such as salamanders, and/or to the surrounding
ecosystems as a whole. The project has the possibility of offering biofiltration, habitat, and
stormwater control elements to the region.
As a class, we have extensively discussed our values and associated goals for the field of
Restoration Ecology. Our values begin with the question: what do we want the new
ecosystem to do? In other words, we examine the desired function of the system to be
restored. This functional goal then provides a framework for research, design,
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construction, and maintenance. We are committed to specifying the operational definitions
which form the foundation of such projects. Our work has lead to questions such as; what
is ecology? What does restoration mean? What are the needs of the community and/or of
the client? What is the path of least resistance, so that we can have the least possible
fina l and ? ncia environmental costs
Our goal for this project is to enhance existing plans for wetland development in
order to get as much value as possible from ecosystem functions, services, and species
preservation.
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Materials & Methods
Species Area Curves: Rarefaction
Rarefaction is the practice of using nested quadrads to determine species
composition and diversity. The process also assists in understanding the species‐ area
relationship of the community in question. Quadrads are carefully measured and laid out
with stakes and wooden frames, after which plant species are identified (or sampled for
identification later in the lab) and recorded.
Over story Transects
This technique is designed to sample forest trees and collects data based on species,
basal area, diameter and dominance. Basal area is the total cross‐sectional area of a trunk
from diameter at breast height (DBH), or horizontal cross section from about four feet
above ground level. Transects are oriented along a compass bearing and stationed at
regular intervals based on the largest tree’s measurements.
Soils
Soil data was collected using pH measurement kits, Munsell soil color identification
charts for determining mineral composition, soil texture classification, and soil
identification using USGS soil maps. Several sample cores of soils were taken with soil
ugers to study soil horizon strata in the area. a
Cover and Land Use History: Aerial Photography Chronosequences & Maps
Aerial photography was collected from the New York State GIS Clearinghouse, and
oil maps were collected from the Olin Library Maps and Geospatial Information Collection. s
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Ithaca College Slope Forest
8
The Ithaca College slope forest is directly uphill from the parking lot wetland where
the sports complex will be built (Figure 1a). Though the area is not large enough on its
own to fulfill mitigation requirements, its close proximity to the impacted land does makes
it desirable for mitigation, provided that the site lends itself to the creation of a wetland.
Research on this site sought to determine its land‐use history and suitability for mitigation
wetlands. This analysis was based upon a 1937‐2007 chronosequence as well as soils data
available from the USDA Natural Resources Conservation Service. In addition, this project
collected original field data in order to determine species composition on the site. This
species data provides additional insight into the history of the site and its suitability for
various kinds of plant species.
The slope forest includes two distinctly different plant communities ‐ the flat lower
reaches are dominated by herbaceous plants, whereas the slope is dominated by woody
species that exhibit a clear transition to mature upland forest. To capture the ground
plants, we utilized nested quadrads, from which data was used to create species area
curves; to capture the tree community, we ran transects uphill through the forest, which
we used to determine basal area percentages (Figure 1b). In both cases, biodiversity was
alculated according to the Shannon‐Weiner index. c
(Figure 1a) (Figure 1b)
Figure 1: Ithaca College slope forest (a) The IC slope forest as seen in a 2007 aerial photograph. (b) Basal area transect points are superimposed in yellow and pink on a slope map. Corner points of a nested quadrad for finding species area curves are superimposed in blue.
9
The 1937‐2007 chronosequence provides a good overview of the site’s history and
characteristics, especially when combined with NRCS soils data (Figure 2). The white
signature visible in the 1937 aerial photograph indicates that the lower reaches of the site
were being used to actively cultivate row crops (Figure 2a). Within these areas, it is
interesting to note the presence of dark patches, which may indicate wet spots where
water collected. This would support the idea that the site has historically experienced
periodic wetting and could thus lend itself to a mitigation wetland. Meanwhile, forest is
visible on the slope in the southwest corner.
The white fields are no longer visible in the 1954 and 1964 photos (Figures 2b, 2
c). Though vertical lines are still visible in the land—a legacy from the planting of row
crops—it is clear that the process of succession has begun. At this stage, the lower reaches
could be characterized as retired agricultural fields, or possibly hay fields. The forest is still
visible in the southwest. It appears that a small area of woods was cleared after 1936 (in
the northern half of the area where transects were taken), but overall, the forest has been
largely undisturbed over the years. By 2007, succession appears to have reclaimed the
former agricultural land to a great extent (Figure 2d). The boundaries delineating the old
fields are no longer obvious in the aerial photo, and trees have taken root throughout the
site.
In addition to the chronosequence, the soils information available for the site says a
great deal about the site’s suitability for wetland mitigation. There is a clear delineation in
which the forested slope consists of Lt soils; whereas the flat lower reaches are a mosaic of
RkB and HsB soils (Figures 2a, 2d). Lt soils are “Lordstown, Tuller, and Ovid soils” that
are shallow and very shallow (20 inches deep over bedrock) — LtB indicates a 0‐15% slope
and LtC indicates a 15‐35% slope. Such soils are somewhat poorly drained; however, due
to the slope of land and the shallow depth to bedrock, LtB and LtC soils are distinctly
unsuitable as a wetland soil. This is important as it reinforces the conclusion that only the
lower reaches exhibiting RkB and HsB soils are good candidates for mitigation.
The RkB and HsB soils are, respectively, a Rhinebeck silt loam and a Hudson silty
clay loam, both very deep and of a 2‐6% slope. The two soil types are geographically
associated, being typical of cultivated fields, and although they are not typical wetland soils,
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their siltiness means that they would lend themselves to this purpose more readily than a
coarser soil would. In its current state, the site already exhibits a mosaic character in which
certain areas are periodically saturated and thus support wetland‐like characteristics,
whereas other areas are dry year‐round. This is likely because the Rhinebeck soil, with
higher clay content, is “somewhat poorly drained” according to the NCRS, whereas the
Hudson soil is “moderately well‐drained.” Thus, Rhinebeck soils are more likely to be wet
and exhibit wetland characteristics. This interpretation is in agreement with Figure 2a, in
hich the darker wet patches are seen to appear over RkB soils. rker wet patches are seen to appear over RkB soils. w
(Figure 2a) (Figure 2b)
(Figure 2a) (Figure 2b)
(Figure 2c) (Figure 2d)
Figure 2: Chronosequence Aerial photographs for (a) 1936, (b) 1954, (c) 1964, and (d) 2007. Soil types are superimposed on 1936 and 2007 photos, depicting the presence of Rhinebeck silt loam (RkB); Hudson silty clay loam (HsB); and shallow to very shallow Lordstown, Tuller, and Ovid soils (LtB and LtC).
Figure 2: Chronosequence Aerial photographs for (a) 1936, (b) 1954, (c) 1964, and (d) 2007. Soil types are superimposed on 1936 and 2007 photos, depicting the presence of Rhinebeck silt loam (RkB); Hudson silty clay loam (HsB); and shallow to very shallow Lordstown, Tuller, and Ovid soils (LtB and LtC).
(Figure 2c) (Figure 2d)
LtB
LtC
HsB
HsB
HsBHsB HsB
RkB
LtB
LtC
LtB
LtC
LtB
LtC
RkB
HsB HsBHsB
HsB
HsB
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In order to obtain a more complete understanding of the HsB/RkB mosaic and its
potential as a wetland, we performed nested quadrads that allowed us to catalog the
ground plants at the site and plot a species area curve. From the species area curve (Figure
4), the number of species found appears to saturate at a point between 15 and 20 species,
giving a minimal area of about 10 square meters. This relatively high level of species
diversity is consistent with successional old fields that have many lingering perennials, a
finding that corroborates what we are able to observe from the chronosequence. The
species list (Figure 3) shows that, although no obligate wetland species were found,
several facultative wetland species were identified. These are plants that are able to grow
in wetland conditions but can survive in non‐wetland conditions, unlike obligate species.
This finding reinforces the site’s promise as a potential mitigation wetland.
Botanical Name Common Name Botanical Name Common Name
Rubus recurvicaulis Dewberry Lonicera morrowii Morrow's Honeysuckle
Carex species Sedge species Rhus toxicodendron Poison Ivy
Carex species Sedge species Elaeagnus angustifolia Russian Olive
Crataegus species Hawthorn species Rubus occidentalis Black Raspberry
Fraxinus americana White Ash Rosa multiflora Multiflora Rose
Duchesnea virginiana Indian Strawberry Leersia virginica Whitegrass
Fraxinus pennsylvanica Green Ash Agrostis hyemalis Winter Bentgrass
Acer rubrum Red Maple Hieracium caespitosum Meadow Hawkweed
Pinus strobus White Pine Solidago flexicaulis Zig‐Zag Goldenrod
Frangula alnus Glossy Buckthorn Dryopteris marginalis Marginal Shield Fern
Veronica officinalis Common Speedwell Taraxacum laevigatum Rock Dandelion
Ligustrum vulgare Common Privet Oxalis stricta Common Yellow Woodsorrel
Triflorum repens Clover Vaccinium corymbosum Highbush Blueberry
Figure 3: Nested quadrad species list Facultative wetland (FACW) species are highlighted in green
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Figure 4: Slope forest species area curve Plants species saturation seems to occur between fifteen and twenty species.
Transects, meanwhile, allow us to observe the transition from these lower reaches
to mature upland forest. In running these transects, we were interested in the ages of the
trees, their species composition, and how these factors change with elevation as we move
away fr
om the HsB/RkB mosaic and into sloping LtB and LtC soils.
The Shannon‐Weiner diversity index was plotted versus transect point number,
along with elevation, in order to obtain a general view of how species composition changes
with elevation (Figure 5). From this figure, there does not appear to be any discernible
trend in overall species diversity as one moves up the slope. However, a more detailed plot
depicting how individual species change in prevalence along the slope show clear patterns
(Figure 6). Certain species, such as Acer saccharum (Sugar maple) and Fraxinus americana
(White Ash), are clearly more numerous in the lower half of the slope, whereas others like
Quercus rubra (Red Oak) and Carya ovata (Shagbark hickory) become more dominant in
the upper half of the slope. This suggests that the slope forest is in a state of transition. The
lower half of the slope was cleared sometime between 1936 and 1954, and the trees that
have grown in since that time are clearly not the same species that were dominant before
that time.
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(Figure 5a)
(Figure 5b)
Figure 5: Diversity change with elevation along western and eastern transects
14 IC slope forest—Change in Species Composition
from Transect Point P1- P15
Num
bero
find
ivid
uals
Figure 6: Change in species prevalence along eastern transect
In addition to plotting transitional changes up the slope, we also sought to
characterize the wooded slope as a whole, in the interest of “looking upstream” of the
potential mitigation site. Figure 7 depicts species dominance in terms of both percent basal
area and number of individuals found. It can be seen from these figures that, although 13
different species were recorded, most of the basal area consists of just four dominant
species. Furthermore, comparing the two dominance plots reveals interesting successional
details. Although Acer saccharam (Sugar maple) is most dominant by both metrics, the
difference is far more dramatic when comparing number of individuals, indicating that its
dominance is achieved by having large numbers of relatively young trees. By contrast, both
dominant oak trees Quercus rubra and Quercus alba (Red & White oak) diminish when
comparing numbers of individuals, indicating that its presence is in the form of a smaller
number of very large, very old trees.
This point is made even more explicit when one plots the size distribution for the
top four most dominant (Shagbark hickory) specimens are less than 46 inches in diameter,
whereas most of the Quercus rubra and Quercus alba (Red & White oak) are larger than 41
inches. This reveals a clear portrait of a forest in successional flux—an old oak forest
radually being supplanted by younger maples and hickory. g
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(Figure 7a)
(Figure 7b)
Figure 7: Species dominance in forest in terms of (a) percent basal area and (b) number of individuals
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QuickTime™ and a decompressor
are needed to see this picture.
(Figure 8a)
(Figure 8b)
(Figure 8c)
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(Figure 8d)
Figu tribution AcerQuercus rub
re 8: Size dis e most dominant tree species of thre sacchar maple (a) aum ‐ sugar
alba(b) ra ‐ red oak (c) Quercus ‐ white oak (d) Carya ovate ‐ shagbark hickory
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Ithaca College Hilltop: Swamp White Oak Swamp & Red Pine Plantation
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The swamp white oak swamp and the red pine plantation are located on a hilltop of
about four acres, just south of the Ithaca College campus. According to chronosequence
photography, the site was an open, abandoned field in 1934, followed by the spread of
swamp white oak specimens by 1964. The red pine plantation was planted in 1964. Tree
core samples confirmed that the oak specimens were approximately seventy years old
while the red pines approximately forty‐five years old. The site falls within a Unique
Natural Area (UNA‐154) (Figure 1). These areas are so named because they possess rare
or valued plants, animals, or topography. They also tend to include some old‐growth trees,
which some of the existing swamp white oaks could be considered. However, the area
should not be considered “pristine” wilderness as it has a history of clearing, farming, and
replanting.
Figure 1: Ithaca College Hilltop location in Unique Natural Area
The red pine plantation exhibits a flat topography while the swamp white oak area
is topographically varied with hummocks and dips filled with water. The soil is similar in
both areas: Eerie Cannery Silt Loam with little sand content and a pH level around 5. Soils
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are not considered hydric; however area is still suitable for a wetland because of a high
fragipan layer that prohibits water from draining quickly from the site.
If swamp white oak were found to be more conducive to biodiversity, it might be
advisable to allow the species to replace the existing red pines. One method to achieve this
is to pull down the red pines with a bulldozer from the road (by keeping the bulldozer on
the existing road, damage to soil structure and existing plants can be reduced
and/avoided). The felled trees would create micro‐topography necessary to create a
wetland similar to what currently exists while opening space for white oaks and other
species. However, as can been seen in Figure 2, the red pine plantation does not adversely
affect bio‐diversity in the area. Also, the cost of such a conversion would outweigh the
small increase in bio‐diversity that such a conversion could produce. Therefore, it is our
recommendation to allow the red pine plantation to co‐exist with the swamp white oak
swamp.
(Figure 2a)
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(Figure 2b)
Figure 2 h nonWeiner Index data : It aca College hilltop Shan(a) Red pine plantation (b) Swamp white oak swamp
References
Hurt, G.W., and Vasilas, L.M. (2006) Field Indicators of Hydric Soils in the United States, US Department of Agriculture and the Natural Resources Conservation Service.
Other Site Concerns
A major issue with the sites on top of South Hill is the presence of the invasive
species Japanese stilt grass (Micostegium vimineum). This aggressively invasive, non‐native
grass has formed large patches mostly along the road that runs between the red pine stand
and the swamp white oak swamp. Stilt grass persists under a wide range of conditions from
moist to dry and low light to high light levels1. It is avoided by all major herbivores in the
area, including white tailed deer which exacerbate the problem through browsing native
species and allowing stilt grass to spread more easily1. Removal of stilt grass is complicated
by the fact that its seeds persist in the soil for five years1. Stilt grass most easily invades
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areas subject to disturbance which explains why the majority of the infestation on South
Hill is along the road1.
There are three main techniques used to remove stilt grass: manual removal,
systemic herbicides, and a combination of manual removal and pre‐emergent herbicides1.
Stilt grass is relatively easy to remove by hand. It has a shallow root system that is easily
pulled from the soil7. Since it is a grass, however, dealing with a stilt grass infestation
requires the removal of many individual plants which can require a greater work force.
When seeds are not present on the plant, stilt grass can be left to dry on site1. If seeds are
present, the plant must be bagged and removed from the area1.
The two herbicides recommended in New York state for use on stilt grass are
Roundup Pro® (Rodeo® in aquatic systems) and Pendulum AquaCap®2. Roundup Pro® is
a non‐selective systemic herbicide that kills nearly all herbaceous plants with the chemical
glyphosate3. It can be applied to stilt grass as either a spray or with a wipe‐on applicator5.
Since this herbicide is non‐specific, using a spray increases the risk of killing non‐target
species. While wipe‐on applicators do reduce this risk, they are slightly more labor
intensive.
Pendulum AquaCap® is a pre‐emergent herbicide that selects for grasses and some
broadleaf weeds6. It uses the chemical pendimethalin to kill seeds in the soil4. It is available
only as a spray; however the selective nature of Pendulum® reduces the risk of this
method of application4. Pendulum® should not be used in aquatic systems as
pendimethalin has been shown to be somewhat toxic to fish and aquatic invertebrates6.
Stilt grass isn’t listed as a controlled species on the Pendulum AquaCap® label; however
studies performed by BASF Chemical Company have demonstrated that Pendulum® is
effective against stiltgrass2, 4.
It is recommended that the stilt grass on South Hill be eradicated through manual
removal over a period of five years in order to ensure full eradication. Herbicides are not
recommended due to the chance of contamination and accidental death of native plants. If,
however, herbicide use is deemed desirable, Pendulum AquaCap® is recommended over
Roundup® or Rodeo® due to its selective nature. This will be most effective if combined
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with one‐time manual removal. Even if herbicides are used, the site should be monitored
for at least 2 years to ensure that all stilt grass has been removed.
Once the stilt grass is removed from the south hill sites, it needs to be replaces with
other plant species in order to deter the stilt grass from returning. The areas of stilt grass
on South Hill seemed unable to displace two species of fern identified as wood fern
(Dryopteris intermedia) and sensitive fern. Many fern species, including the wood fern, are
capable of allelopathy, or producing chemicals that kill off neighboring plants allowing the
fern to live healthily and spread easily8. As the situation on South Hill suggests, it is
possible that the allelochemicals produced by the wood fern are effective against stilt grass.
It is recommended that any stilt grass removed from South Hill should be replaced with
wood ferns since it a native species already present on South Hill that is likely resistant to
stilt grass invasions.
References
1 Swearingen, J.M., 2008. Least Wanted: Japanese Stilt grass. Plant Conservation , Alliance. http://www.nps.gov/plants/ALIEN/fact/mivi1.htm. Accessed Nov. 14
2008. 2 BASF Corporation, 2005. A Better Approach to Controlling Japanese Stiltgrass.
v. 19, http://www.vmanswers.com/lib/PDF/japanesestiltgrassss.pdf. Accessed No2008.
3 Tu, M., Hurd, C., Robinson, R., and Randall, J.M., 2001. Weed Control Methods Handbook: Tools and Techniques for Use in Natural Areas. The Global Invasive
n E: 115‐125. 008.
Species Team. The Nature Conservancy. Chapter 7, Sectiohttp://tncinvasives.ucdavis.edu/handbook.html. Accessed Nov. 15, 2
4 BASF Corporation, 2006. Herbicide Pendulum AquaCap. http://www.cdms.net/LDat/ld3BO006.pdf. Accessed Nov. 18, 2008.
5 Monsanto Company, 2007. Roundup Original Max Herbicide. http://www.monsanto.com/monsanto/ag_products/pdf/labels_msds/roundup_orig_max_label.pdf. Accessed Nov. 18, 2008.
6 Extension Toxicology Network, 1993. Pesticide Information Profile: Pendimethalin. http://pmep.cce.cornell.edu/profiles/extoxnet/metiram‐propoxur/pendimethalin‐ext.html. Accessed Nov. 15, 2008.
7 Arlington, VA: Parks, Recreation, and Cultural Resources. 2008. Japanese Stilt Grass Alert. http://www.arlingtonva.us/departments/ParksRecreation/scripts/parks/ParksRecreationScriptsParksInvasiveJapaneseAlert.aspx. Accessed Nov. 18, 2008.
8 Munther, W.E. and Fairbrothers, D.E., 1980. Allelopathy and autotoxicity in three eastern North American ferns. American Fern Society, 70:124‐135.
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Ithaca College Parking Lot: Wetland Corridor
& Downstream Corridor
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The Ithaca College Parking Lot Wetland is being destroyed during the construction
of the new Ithaca College athletic facility. It was important to examine the history and
vegetation and soil characteristics of this wetland both because of the potential to build
some of the elements of the original wetland into the stormwater management wetlands
that will be constructed as part of the athletic facility project and because the purpose of a
mitigation wetland is to replace the functions provided by the wetland that has been lost.
Figure 1: Ithaca College parking lot wetland area: blue dots indicate the station points of the plant species transect.
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(Figure 2a)
(Figure 2b)
27
(Figure 2c)
F : Ariel Ch Ithaca College’s Lower Quad has been constructed.
igure 2 ronosequence of the Ithaca parking lot wetland Area largely cultivated. Transect is noted in red dots. (a) 1936,
(b) 1964, (c) 2007, Land use changes (parking lots have increased runoff) have relatively recently introduced hydromorphic soil processes.
The soil data and aerial chronosequence images suggest that there has been a
greater water accumulation on the site over time. In the 1936 aerial, the site does not
appear to be a wetland – it is clearly an agricultural area. The soil type specified in the soil
maps for the area also does not indicate a classic wetland soil type (Figure 3 and Table 1).
RkB, standing for Rhinebeck Silt Loam, is typically found in areas with slopes of 2‐6%, and
the depth to a root restrictive layer is greater than 60”. This soil is somewhat poorly
drained, but not ponded or flooded, and the seasonal zone of water saturation is at 10”
from November to May. Typically, this soil does not meet hydric criteria. Given that the
site in 1936 does not appear to be a wetland (Figure 2a), and that the soil would not
typically support a wetland, it would seem that the wetland conditions currently existing
28
on this site are due to a larger volume of water entering the site. As posited above, this is
likely due to the increased impervious area adjacent to the site, which has in turn increased
runoff into the site. The inundation of the site over the past few decades has resulted in
more hydric soil conditions and fostered the success of an increased number of typical
wetland plants (Table 2) , which currently share the site with species indicative of old field
sites.
Figure 3: Soils map overlaid on an aerial of the site. Plant species transect is indicated by blue dots.
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Soil Sample Horizon pH Texture Soil Color Mottling Soil Type
1 A 6.4 Silty clay 5Y 3/1 No RkB
1 B1 6.4 Silty Clay 2.5Y 5/2 Yes RkB
1 B2 6.6 Silty Clay 2.5Y 4/2 Yes RkB
Table 1: Soil Sample Characteristics
Because of the density of vegetation on this site, a nested quadrad system was not
used to look at species diversity and community makeup. Instead, a 100m transect was
laid out with stations every 10m. At each station a 2m‐by‐2m square was laid out centered
on and perpendicular to the transect line. Each species found within the square was
counted once, to create a data set that would capture the variety of species and their spatial
distribution across the transect. This method of data collection does not provide insight
into species distribution density, as with the nested quadrad data gathered for the other
sites studied. The plant species data collected on this site is intended to provide insight
into the character of the wetland that is being lost (How wet is it? Is the plant community
indicative of a wetland or old field condition, or a combination of the two?), to inform the
decisions about what the functions and plant community makeup of the mitigation
wetland(s) should be.
Number of Species at Each Plot
0
5
10
15
20
25
Num
ber o
f Spe
cies
Col
lect
ed
0m 10m 20m 30m 40m 50m 60m 70m 80m 90m 100m
Plot Number
30
Figure 4: Plant species varied at each transect point across the wetland.
Species Collected Most Frequently Across Transect Plots
*blue‐highlighted species are invasive
Species Botanic Name Common Name # of Times Collected
Solidago canadensis var. canadensis Canada Goldenrod 7
Aster spp. 1 Aster species 6
Calamagrostis spp. Reedgrass species 6
Rosa multiflora Multiflora Rose 6
Solidago patula var. patula Roundleaf Goldenrod 6
Frangula alnus Glossy Buckthorn 5
Geum rivale Purple Avens 5
Ligustrum spp. Privet species 5
Fraxinus americana White Ash 4
Geum macrophyllum Largeleaf Avens 4
Prunella vulgaris Common Selfheal 4
Cornus stolonifera Red‐twig Dogwood 3
Juncus effusus Common Rush 3
Polygonum spp. Knotweed species 3
Table 2: Most common species collected.
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D
ownstream Corridor
1
9
11
20
Meets Six‐Mile Creek
Figure 5: The stream exiting the wetland and joining SixMile Creek. The red dots are station marks at inlets and outlets.
32
(Figure 6 – a)
(Figure 6b)
33
(Figure 6c)
(Figure 6d)
34
(Figure 6e)
Figure 6 o: D wnstream Area Photography
(a) Station 1. At the outlet from the wetland, the bank has been eroded, as shown by the bank character and the exposure of the roots of this tree. The bank under the tree has been undercut to a depth of 0.5m.
(b) Station 9. After the stream passes through a series of culverts on the I.C. campus, it daylights again between road crossings. Here there begins to be stands of Japanese Knotweed along the banks of the stream.
(c) Station 11. At this point the stream flows between two yards in a very flat area. In the photo you can see young Japanese Knotweed starting to come up from what seemed to be an eradication effort.
(d) Station 20. Here the stream has carved out a deep gully – approximately 10’ deep. Dense scrub lines the banks of the gully. The streambed flattens out as it enters an area of denser undergrowth, and flows in to fenced‐off private property.
35
(e) End: Meets Six‐Mile Creek. The stream eventually flows into Six‐Mile Creek, which in turn runs through downtown Ithaca into Lake Cayuga.
Stations Marking Downstream Path
1. N42° 25' 28", W76° 29' 26" ‐ head of stream
e 2. N42° 25' 28", W76° 29' 26" ‐ 2.1 m wide + .5 m under tre
ch basin 3. N42° 25' 28", W76°29' 26" ‐ drainage grate‐ cat
‐ catch basin/grate 4. N42° 25' 30", W76° 29' 27"
5. N42° 25' 31", W76° 29' 26"
6. N42° 25' 32", W76° 29' 25" ‐ from culvert‐out
7. N42° 25' 34", W76° 29' 24" ‐ <6" standing water 2' bfd
8. N42° 25' 34", W76° 29' 24" ‐ (.7 m big) culvert in 0.8 m water frogs!
9. N42° 25' 35", W76° 29' 23" ‐ (2 m big) culvert out 0.3 m deep water bfd 1.4 m
m stream width 1.4 m bfd 10. N42° 25' 37", W76° 29' 22" ‐ (.7 m big) culvert in 2.5
11. N42° 25' 37", W76° 29' 22" ‐ culvert out .6 m depth
12. N42° 25' 37", W76° 29' 21" ‐ 1.1 m width 1" deep water
n't tell how deep‐stones 13. N42° 25' 38", W76° 29' 20" ‐ culvert in 3 m wide ca
14. N42° 25' 38", W76° 29' 20"‐ culvert out .7 m depth
t in 2.2 m width 15. N42° 25' 40", W76° 29' 18" ‐ (2.5') culver
16. N42° 25' 40", W76° 29' 18" ‐ culvert out
17. N42° 25' 40", W76° 29' 18" ‐ 2.3 m bfd 3 m wide 2" deep water
m wide 2" water depth 2' bfd 18. N42° 25' 41", W76° 29' 17" ‐ culvert in 3
19. N42° 25' 41", W76° 29' 17" ‐ culvert out
anks) 20. N42° 25' 42", W76° 29' 15" ‐ 3.9 m wide 1' bfd (deeply cut b
21. N42° 25' 43", W76° 29' 13" ‐ 3 m wide bfd 6" 2" deep water
22. N42° 25' 52", W76° 29' 17" ‐ culvert in 2.3 m wide 6" bfd no water gabions
36
23. N42° 25' 51", W76° 29' 14" ‐ (3' tall) culvert in 3.2 m width 2' bfd24. N42° 25' 49", m wide .5 m bfd culvert out is about 50' downhill W76° 29' 11" ‐ culvert in 5
nd: Meets Six‐Mile Creek. E
Conclusion
The destruction of the I.C. parking lot wetland will certainly have impacts
downstream. The stream flowing out of the wetland already shows signs of instability and
invasive species, and the stormwater management plan for the new athletic complex
project will have to account for this.
The aerial photographs, USGS soil data and plant species information for the I.C.
parking lot wetland indicate that this site was not historically a wetland, but has more
recently become one. This is likely due to the site receiving increased amounts of water
that has come from the parking lots and other impervious surfaces built adjacent to the
site. Because of this history of change, the site currently has a mix of old‐field vegetation
and wetland vegetation.
In constructing the mitigation wetland, it should be considered that the current
function of this wetland has been to detain and filter runoff from parts of the Ithaca College
campus. Additionally, the plants that are surviving in this wetland are a naturally surviving
community that have been capable of establishing themselves, successfully propagating,
and surviving in the conditions on‐site. While the plant species found in the parking lot
wetland do not seems to be species of particular value, they can serve as an example of a
community of plants that would function well and without significant maintenance in
constructed wetlands that are designed to serve the same purpose: detention and
infiltra ion of stormwater runoff. t
37
Proposed Stormwater Management Plan
38
Backgr
ound Ithaca College is in the process of building a new athletic facility and fields on their
South Hill campus. This project will displace the parking lot wetlands mentioned earlier.
These wetlands served the valuable function of handling the runoff from the impervious
surfaces as well as providing habitat for various organisms. In this section we examine
how the proposed stormwater management strategy will effectively replace the functions
the parking lot wetland provided.
Figure 1: Proposed Ithaca College sports complex
39
Figure 2: Ithaca College Planned Athletic Facility Site
S tormwater Management Strategy
The storm water plan incorporates a series of bioretention filters to capture runoff
from fields and facilities, parking lots and roads. These infiltration areas are designed to
capture the water quality volume for the 2 year 24‐hour storm. The treatment train begins
with a series of 8 small bioretention filters and terminates in one larger retention pond. A
sand filter is incorporated to handle runoff from the playing field. According to the plan it
appears that three of the smaller bioretention filters actually tie directly into the larger
pond, two of the filters outfall directly into the landscape as overland flow, and three outfall
to the existing piped stormwater system. in
40
Figure 3: Ithaca College Athletic Facility Proposed Stormwater Management Plan
Figure 4: Detail of a Bioretention Filter from Project Design Development Document
41
F igure 5: Detail of the Detention [sic: Retention] Pond from Project Design Development Document
Plan
ting Strategy
One of the elements of the landscape plan that could be modified is the planting plan,
particularly concerning the plants associated with the bioretention filters and retention
pond. The planting strategy revealed in the construction documents seems to be one of
incorporating a broad array of diverse species to create a sort of wetland mosaic. In order
to assess how effective this strategy will be, we cross referenced the plant list to the USDA
PLANTS database to see how they classified the plants in terms of wetland hydrologic
zones. Most of the species fell under the categorization of obligate (OBL), meaning they
occur almost always under natural conditions in wetlands, facultative wetland (FACW),
meaning they usually occur in wetlands but are occasionally found in non‐wetlands, or
facultative (FAC), meaning they are equally likely to occur in wetlands or non‐wetlands.
The planting plan for the bioretention filters and retention pond were broken into specific
ones with the following proportions of species types: z
• L & 2 FACW Emergent shallow planting – 4 OB
• Emergent deep planting – 4 OBL
42
• Bio‐swale seed mix (for the bioretention fil
• Upland moist seed mix – 8 OBL & 6 FACW
ters) – 11 OBL & 10 FAC or FACW
Figure 6: Plant list from Proposed Planting Plan Cross Checked Against the USDA PLANTS Database
Due to reliance on meteoric inputs the retention areas will experience prolonged
periods of dryness, which suggests that they are not suitable areas for obligate wetland
species. Obligate species live in areas of nearly constant soil saturation. We recommend
selecting plants that can tolerate the stresses inherent in storm water management
structures such as these. In particular, plants should be selected for tolerance to prolonged
drought and intermediate flooding, as well as possibly high inputs of nutrients and other
pollutants carried in runoff.
Based on the relatively high amount of species included in the planting list, it seems
that the strategy for the plantings is to have a diverse mosaic of species. However, we
predict that a strategy that employs lower density plantings of multiple species is likely to
43
be taken over by a narrow range of more aggressive species like Typha, Phragmites, and
Phalaris. We know that Typha is present in the existing parking lot wetlands. It is likely
that their propagules are ubiquitous throughout the site as well. If the intention is to avoid
monoculture of these more aggressive species, then we suggest that fewer species are
hosen and planted in higher densities to promote establishment and resist invasion.
a
c
Figure 7: Crosssection of proposed Detention [sic. Retention] Pond
44
Figure 8: Juncus effusus in a roadside swale. This condition is analogous to the bioretention filters, a shallow depression receiving runoff from a paved surface. The high plant density resists invasion from typical ditch species like Typha, Phragmites, and
Phalaris.
Figure 9: Typha sp.
45
Figure 10: Phragmites sp.
Figure 11: Phalaris arundinacea (Reed canary grass)
46
Use ng Resources As Figure 12 indicates, the parking lot wetlands that are going to be demolished contain
several species that were listed in the proposed plant list. Before the existing wetland is
demolished there is an opportunity to transplant some of these species into the new
iofiltration ponds.
Existi
b
Figure 12: Plants on the proposed planting list found in the Ithaca College parking lot wetlands
47
Figure 13: Surveying the shallow slopes at Bull Pasture Pond, a potential reference site.
Figure 14: Mixed wetland species
48
R ecommendations
• Plant selection should target a biological benchmark with regards to saturation
evels and duration. l
• A smaller more selective plant list and higher density planting can help compete
ith local invasives. w
• hoose and collect beneficial plants from the existing wetland before demolition. C
• The stormwater plan includes features that should be celebrated as a part of the
Ithaca College Campus’s functional landscape. Although the area comprised of the
constructed wetlands planned for stormwater management will not count towards
the required legal mitigation effort, they will serve a functional role in mitigating
stormwater runoff generated by increased impervious surfaces. This feature should
be highlighted as an effort which goes above and beyond the baseline best
anagement practices. m
• The need for continued monitoring and maintenance should be heeded. Possibly
tying the functions of the stormwater retention areas to research agendas presents
another angle for in‐depth monitoring. Creating functional landscape that will serve
as habitat space could generate interest on the part of resident researchers; the
effect being more holistic monitoring practices.
49
RPM Old Field in Dryden
50
Ithaca College's initial assessment of the potential onsite mitigation wetland
location determined that slope; cost and future expansion interests posed problems with
that option. The College then began to look elsewhere and came to consider an old field
adjacent to Route 13 west of the village of Dryden. The owner of this property is RPM
Ecosystems LLC, a native plant nursery which grows plant material specifically for
restoration and conservation projects using their patented Root Production Method
(RPM).1 The class was informed that RPM was interested in having a wetland constructed
on their property and even entertained having it sized larger than the area mandated by
the United States Army Corps of Engineers (USACE). The Dryden site is 10.7 acres and
located in the Virgil Creek Watershed which drains into Fall Creek and eventually Cayuga
Lake. (Figure 1a and 1b) It is important to note that the site is in a different sub‐watershed
from the proposed wetland impact on Ithaca's South Hill. From analyzing Geographic
Information System (GIS) data and USGS Quads it was determined that the Dryden site as a
whole was less than 5% slope and that perennial streams bordered the site in the form of
drainage ditches.
1 RPM Ecosystems LLC. http://www.rpmecosystems.com/about_rpmecosystems.html Visited November 25, 2008.
51
(a) (b)
(c)
52
Figu 1re : Watersheds
(a) Lar
ge scale watershed of Dryden site (b) Local watershed of Dryden site (c) Diagram of the water flow on through Dryden site and the adjacent wetlands
To determine whether the site would make a suitable wetland, the class pursued a line
of questioning related to the history and physical characteristics of the site. One critical
question that we sought to answer was whether the site ever was a wetland previously.
This would mean that transforming the site back into a wetland would be much easier.
Through a combination of remote sensing and field investigation we hoped to determine
the sites suitability as a wetland. Through assembling an aerial photograph
chronosequence with a first image dating from 1938, it was clear that the land use on the
site had been consistently agricultural for the past 70 years. (Figure 2a and 2b) This did not
discount the possibility that the site was a wetland prior to this period, as hydrologic
modifications often accompany agricultural activities. In the aerial photographs, adjacent
sites did revert to wetlands over time and are now identified on the National Wetland
Inventory. In studying the area's soil map, we determined that because of poor drainage,
low slope, the Halsey Silt Loam soil group which comprises the bulk of the site meets hydric
criteria.2 (Figure 2c) This fact coupled with a high zone of water saturation and low relief
make the Dryden site more suitable for wetland creation than some of the other sites we
investigated.
2 USDA Natural Resources Conservation Service, soil descriptions available. http://soildatamart.nrcs.usda.gov/State.aspx Visited November 15, 2008.
53
(a) (b)
(c)
54
Figu 2re : Site Maps
(a) 1 938 Aerial photo showing history of site as a farm field
(b) 2007 Aerial photo (c) Soils map showing that Halsey silt loam dominates site and meets criteria for a wetland
After examining soil characteristics and historical conditions a closer look at the
topography and hydrology was necessary. According to a longitudinal cross‐sectional
transect using rod and level, it was established that the field sloped 2.9% towards the
North. (Figure 3) A slight natural terrace occurred 250 feet to 350 feet from the road edge.
It was determined that two culverts conveyed surface runoff from the upper portion of the
watershed underneath Route 13 and discharged the flow into drainage ditches loosely
forming the western and eastern edges of the site. Redirecting flow from these constructed
drainage structures is one possible way to create wetland conditions on the old field. We
then briefly investigated what level of grading would be necessary to create a redirection
swale, small reservoir, dike, water control structure and subsequent wetland area;
essentially a schematic design. (Figure 3) It was determined that these structures could
effectively be built in the area provided. However, if wetland area is to be maximized
beyond the 4.4 acres required, there will be a great deal of excess cut material. Alternately,
if the construction is formed closer to the natural slope, the total dedicated wetland area
will be diminished.
55
Figure 3: Wetland Scheme
These diagrams show some of the principle concepts that would be involved in creating a wetland on the Dryden site. The bottom graph shows the change in slope that would be needed on site to create a wetland.
Existing plant communities are indicators of wetland conditions, successional
history and biodiversity. The class established two nested quadrads at the Dryden RPM
site. One was higher on the slope to the southern end of the site and the second test area
was downhill to the north. (Figure 4a and 4b) No facultative wetland or obligate wetland
species were discovered nor were any rare or threatened upland species. No basal‐area
curve data collection was performed at this site since the vegetation was predominantly
herbaceous. Solidago species represented the highest percentage of overall cover in both
quadrads. The lower site had slightly greater plant diversity based on the Shannon‐Weiner
Index. (Figure 4c) Cattail (Typha sp.) and Purple Loosestrife (Lythrum salicaria) were
56
identified and photographed in the drainage ditch along the western boundary of the field.
(Figure 4d and 4e) These aggressive species could effect and displace the desired plant
communities of a mitigation design on this site.
(a)
(b)
57
(c)
(d) (e)
Figu 4re : Dryden Plant Data
(d) Upland Meadow Species Area Curve ea Curve data used to make Shannon‐Weiner Index at both locations
(e) Lowland Species Arrea Curveoosestrife
(f) Species a(g) Purple L(h) Cattails
58
Conclusion:
Finally it is important to consider what function the Dryden RPM Field could serve
as a wetland. It could play a role in stormwater management, runoff treatment, or as
habitat for a species such as Ambystoma Salamanders. From observing the drainage
ditches at the field edges it did not appear that erosion was a serious problem. Route 13
and other impervious surfaces related to development account for only a small percentage
of the upstream watershed area. There is an auto‐mechanic shop and a great deal of
agricultural land in the catchment that could potentially be targeted for treatment in a
wetland on the site. In terms of habitat, the site is not suitable for salamanders until some
forest cover is able to develop but it may prove to be valuable for frogs. So ultimately, it is
possible to construct a wetland on this old field. Stakeholders must evaluate if the
functional gains are worth the cost. In terms of replacing the functionality of the Ithaca
ollege wetlands, location alone discounts this site. C
59
Special Considerations: Amphibian Breeding Habitat
& Amphibian Habitat Recommendations
60
Amphibian ecology
Habitat loss and fragmentation as a result of land use change contribute to
amphibian population declines on a global scale (Collins and Storfer 2003). In North
America, small wetlands, including vernal pools, are destroyed at a significant rate. These
ponds support a diversity of amphibian populations, which use the ponds for breeding and
metamorphosis (Semlitsch and Bodie 1998). Creation of breeding pond habitat can act to
counter wetland loss and connect patchy or isolated amphibian populations. Amphibians
also prove useful indicators of habitat quality due to their sensitivity to environmental
changes and toxicity. Amphibians use cutaneous respiration in that they can breathe
through their skin, which means that environmental toxins are also absorbed through their
skins. Additionally, amphibian populations can be used to assess restoration success due
to their sensitivity to altered hydrology (Petranka et al. 2003).
Several species of amphibians, which includes salamanders and frogs, utilize ponds
for different stages of their life cycle. Mole salamanders in particular depend upon pond
habitat. Locally, there are two species of mole salamander: the spotted salamander
(Ambystoma maculatum) and Jefferson’s salamander (Ambystoma jeffersonianum). Aptly
named, mole salamanders burrow underground in hardwood forest habitat for most of the
year. In early spring once the spring rains begin, these salamanders migrate to permanent
or ephemeral ponds where they breed and deposit egg masses in the water. Salamanders
then develop and metamorphose within the pond and migrate back to the forest habitat
(Conat and Collins 1998). The Eastern newt (Notopthalmus viridescens) and several frog
species, such as the wood frog (Rana sylvatica) and gray treefrog (Hyla versicolor) also
utilize terrestrial‐aquatic habitat linkages for breeding and development aspects of their
ife histories. l
Reference site: Bull Pasture Pond
Bull Pasture Pond, located on the Robert Trent Jones golf course in Ithaca, New York
serves as a reference site for local salamander breeding habitat (Figure 1b). The two local
61
Ambystomid species, the spotted salamander (Ambystoma maculatum) and Jefferson’s
salamander (Ambystoma jeffersonianum), migrate across the golf course between forest
and pond habitats during breeding season.
(a)
(b)
Figure 1: Bull Pasture Pond: (a) Aerial view of Bull Pasture Pond and surrounding golf course and woodland. The distance required for migration between the pond and forest is about 320 feet. b) Panoramic view of Bull Pasture Pond and surrounding landscape. The right pond was surveyed as a
reference site and offers shallow sloped sides and a vegetated perimeter. (
Proximity to upland forest provides the necessary aquatic‐terrestrial linkage for
different stages of the Ambystomid life cycle. Distance from Bull Pasture Pond to the
nearest patch of woodland is about 320 feet (Figure 1a). Transects through the woodland
were used to determine species composition; mature hardwood trees dominate the upland
forest (Figure 2a). A soil profile was also characterized with regard to pH, texture, and
62
color (Figure 2b). Vegetation along the perimeter of the pond consists of several
herbaceous species, including the invasive purple loosestrife (Lythrum salicaria) (Figure
2c). This vegetated buffer around the pond acts for primary production and habitat for
salamanders. Vegetation overhanging or submerged in the shallow water can be utilized
for salamander egg deposition.
Topography of the pond also influences its suitability for salamander breeding
habitat. Three cross sections were surveyed along the stream, with elevation
measurements taken at regular intervals (Figure 2d). A topographic profile was created
with height and depth data from cross‐sectional surveys (Figure 2e). The profile indicates a
shallow pool with gently sloping sides and an irregularly shaped perimeter contour.
Shallow water depths allow for growth of submerged aquatic vegetation (SAVs), which
provides food and habitat for salamander populations. The sloping sides allow for ease of
access to and from the pond as necessary for breeding and development. An irregular
perimeter provides habitat heterogeneity and complexity.
Tree species Common name
Acer rubrum Red maple
Carpinus caroliniana American hornbeam
Carya glabra Pignut hickory
Carya ovata Shagbark hickory
Fraxinus americana White ash
Fraxinus pennsylvanica Green ash
Larix decidous European larch
Picea abies Norway spruce
Pinus strobus White pine
Prunus serotina Black cherry
Quercus alba White oak
63
Quercus palustris Pin oak
Quercus rubra Red oak
Quercus velutina Black oak
Tsuga canadensis Eastern hemlock
(a)
Horizon Color Texture pH
1 10YR 4/3 Loam 5.5
2 2.5Y 5/4 Clay loam 5.8
3 5.1
(b)
Species Common name
Dulichium arundinaceum Threeway sedge
Boehmeria cylindrica False nettle
Verbena hastata Swamp verbena
Lythrum salicaria Purple loosestrife
Scirpus cyperinus Woolgrass
Polygonum sagittatum Arrowlead tearthumb
Solidago canadensis Canada goldenrod
Bidens cernua / (laevis?) Nodding beggartick
(c)
64
(d)
(e)
65
Figure 2: Graphs and Tables (a) Tree species found in the upland forest surrounding Bull Pasture Pond (b) Soil characteristics of a core sampled in woodlands adjacent to Bull Pasture Pond. Soil horizons were
distinguished based on color differences, as determined with a Munsell color chart. Soil texture was determined by the texture-by-feel method. A field test kit was used to measure soil pH. Fragipan was present at a depth of 16 inches.
(c) Vegetation present along the perimeter of Bull Pasture Pond. (d) Sampling transects across Bull Pasture Pond to determine topographic profile. Each measurement was
recorded from a single survey point on the pond edge. (e) Topographical profiles of Bull Pasture Pond, with proportional height and depth scales.
Invasive species concerns
Invasive plants and animals are opportunistic and frequently colonize disturbed
sites. Monitoring and control methods are recommended to stem the spread of invasive
species. Two invasive species of potential detriment to Ambystomid breeding habitat are
ullfro ails.
b gs and catt
Bullfrogs (Rana catesbeiana) were originally introduced into the United States for
their culinary value; since introduction the animal has successfully and persistently spread
throughout many habitats. Bullfrogs will eat any animal that can be swallowed, including
juveniles of their own species. This voracious predator negatively affects native species, as
adults and young may be eradicated from an area as they fall prey to the bullfrogs.
Institution of a desiccation regime in pond habitat has been demonstrated to reduce
bullfrog populations (Maret et al. 2006). For example, in Arizona’s San Rafael Valley,
bullfrogs colonized cattle ponds originally intended as habitat for the native Sonoran tiger
salamander (Ambystoma marortium stebbinsi). Manipulation of pond water levels to mimic
seasonal changes showed a negative effect on bullfrogs, as constant water inundation is
beneficial for bullfrog growth and development. Bullfrog tadpoles require more than one
season to mature and the adults over winter in the mud at the bottom of the pool.
Desiccation of the pool and underlying sediments thus works to reduce bullfrog
populations (Maret et al. 2006). Fencing has also been proposed as a method to exclude
bullfrogs from habitat (Bovinderajula et al. 2005), although this technique would have
other spdetrimental effects on ecies, including the salamanders.
Cattails (Typha latifolia) are another species of potential invasive threat to wetland
habitat. Although this is a valuable species for water quality and waterfowl habitat in some
66
cases, it quickly forms a monoculture and creates a barrier along the shoreline.
Manipulation of the water level, timed to the annual cycle of carbohydrate storage, works
to control cattail colonization. Leaf and stem cell aerenchyma provides air passage from
both living and dead leaves to the rhizomes. Submergence of the shoots and dead leaves in
the spring will thus cause stress to the plant growth and eventually kill it (Sojda and
Solberg 1993).
Site suitability analysis
Suitability of a site for amphibian habitat depends upon a number of factors,
including the context of the surrounding upland and soil characteristics. Different
communities of amphibian populations should be expected based on the upland context
within which the pond is created. Ambystomid, or mole, salamanders prefer mature,
hardwood forests for growth and development when not in breeding season. This type of
forest provides necessary leaf litter decomposition and invertebrate communities for the
spotted and Jefferson’s salamander. Acidity also influences salamander survival success
and rate of metamorphosis. At pH levels less than 4.5, Ambystomid salamanders exhibit
decreased survival and slower rates of development in breeding ponds (Sadinski and
Dunson 1992). Salamanders typically prefer pH levels above 6.
Of the mitigation sites, the Ithaca College wooded slope site provides the most
appropriate context for Ambystomid salamanders. The forest is predominately comprised
of hardwood trees, and has existed for several decades, allowing maturation of forest soils.
The Ithaca College red pine site also provides a woodland context, although located within
a pine forest instead of hardwood upland. Pine needles produce acidic leaf litter, which is
detrimental to salamander growth and development. Soil samples at the red pine site were
around pH 5; this is less than ideal for amphibians, but not unmanageable.
Another site in the process of consideration for mitigation, the RPM‐Dryden field,
presents different issues for amphibian habitat. This site lacks woodland habitat necessary
to support salamanders that require both terrestrial and aquatic habitat. Spotted
salamanders, Jefferson’s salamanders, and Eastern newts should not be expected to
populate a pond created at this site. The field site, however, could be use for frog habitat,
67
as many local frog species utilize pond habitat that do not require adjacent woodland.
Some frog species that might be expected to colonize such a site include spring peepers
(Pseudacris crucifer), green frogs (Rana clamitans), pickerel frogs (Rana palustris), and
leopard frogs (Rana pipiens). Soil tests at this site indicate a range of pH values, from
moderately acidic (5.3) to circumneutral (6.8). These pH levels are more conducive to
mphibian habitat than sites with strongly acidic soils. a
Amphibian pond recommendations
Wetland creation for amphibian habitat should take into account factors of pond
size, quantity, spatial arrangement, complexity, and hydroperiod (Petranka and Holbrook
2006).
Prior studies indicate that wetland hydroperiod is a more significant predictor of
amphibian colonization than wetland size (Snodgrass et al 2000). The wetland
hydroperiod determines the timing and duration of water inundation and drawdown
within a wetland. Hydroperiods occur along a gradient from permanent water inundation
to ephemeral, in which water is only present for a short period of time. Amphibians are
adapted to capitalize on available water sources, for which variable hydroperiod might be
present. Variation in hydroperiod also allows a balance between the threats of desiccation
and predation. Permanent ponds offer a constant habitat for breeding and development
throughout the year, albeit a characteristic also conducive for invasive species such as
bullfrogs. Ephemeral ponds hold water primarily over the seasons when pond habitat is
utilized, although rate of desiccation due to size or other factors presents a stress to
amphibian development rate. Wetland hydroperiod, coupled with surrounding terrestrial
landscape, will determine amphibian assemblages following wetland creation (Petranka
and Holbrook 2006).
Creation of the wetland habitat should exhibit structural and functional
heterogeneity, such that a variety of amphibian species colonize the wetland for different
attributes. Fish should not be introduced to the created pond, as they prey upon amphibian
individuals and egg masses and reduce species richness (Hecnar and M’Closkey 1996).
Variation of wetland depth, size, micro‐topography, and hydroperiod along a spatial
68
gradient will provide the greatest habitat complexity suitable to a wide variety of
organisms. The perimeter of the pond should be complex and vegetated to provide further
food and habitat resources.
Literature Cited Bovinderajula, P., R. Altweggot, and B.R. Arholt. 2005. Matrix model investigation of invasive species control: bullfrogs on Vancouver Island. Ecological Applications 15(6): 2161- 2170. Collins, J.P. and A. Storfer. 2003. Global amphibian declines: sorting the hypotheses. Diversity and Distributions 9: 89-98. Conat, R. and J.T. Collins. 1998. A field guide to reptiles and amphibians of eastern and central North America. Houghton Mifflin. Hecnar, S.J. and R.T. M’Closkey. 1996. The effects of predatory fish on amphibian species richness and distribution. Biological Conservation 79: 123-131. Maret, T.J., J.D. Synder, and J.P. Collens. 2006. Altered drying scheme controls distribution of endangered salamander and introduced predators. Biological Conservation 27(2): 129- 138. Petranka, J.W. and C.T. Holbrook. 2006. Wetland restoration for amphibians: should local sites be designed to support metapopulations or patchy populations? Restoration Ecology 14(3): 404-411. Petranka, J.W., C.A. Kennedy, and S.S. Murray. 2003. Response of amphibians to restoration of a southern Appalachian wetland: a long-term analysis of community dynamics. Wetlands 23(4): 1030-1042. Sadinski, W.J. and W.A. Dunson. 1992. A multilevel study of effects of low pH on amphibians of temporary ponds. Journal of Herpetology 26(4): 413-422. Semlitsch, R.D. and J.R. Bodie. 1998. Are small, isolated wetlands expendable? Conservation Biology 12(5): 1129-1133. Snodgrass, J.W., M.J. Komoroski, A.L. Bryan Jr., and J. Burger. 2000. Relationships among isolated wetland size, hydroperiod, and amphibian species richness: implications for wetland regulations. Conservation Biology 14(2): 414-419.
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Sojda, R.S. and K.L. Solberg. 1993. Management and control of cattails In Waterfowl management handbook. < http://www.nwrc.usgs.gov/wdb/pub/wmh/13_4_13.pdf>
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Conclusions and Recommendations
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General Recommendations:
It is important for mitigation wetland goals to reflect desired functions. Stormwater
management, treatment, and the successful establishment of an appropriate plant
community can all be primary elements of any goal statement. Habitat, specifically for
endangered animal species, such as Ambystomid salamanders, would then add further
alue to this project. v
Conclusions:
The slope forest at Ithaca College does not have the required acreage to satisfy
Ithaca College’s mitigation wetland needs, however the conditions in lower topographical
areas are conducive to wetland creation. The contiguous nature of the existing wet areas
(currently seasonal wetlands) and the location of the site within the same watershed/
hydrologic system as the existing wetlands make this site viable for our purposes. Also,
evidence of succession is available for this site resulting in the ability to make general
predictions as to what plant association is developing. This data could be used to inform
any planting scheme for the site. Therefore, we recommend considering the possibility of
locating a portion of the required mitigation wetland acreage on this site. Remaining
acreage could then be located on a separate project site.
The swamp white oak swamp and the red pine plantation are functional ecosystems
which are working components within the watershed. These areas cannot fulfill the
required acreage of mitigation wetland needed. Further, extending the swamp white oak
swamp into the red pine plantation seems extremely costly when compared to gained
benefits. We do, however, recommend the protection of these communities by removing
and creating a management plan to control Japanese stilt grass. This highly invasive
species poses an extreme threat to the existing community structure.
The Ithaca College parking lot wetland’s existing plant association is an appropriate
reference community with regards to a functional wetland created by increased overland
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runoff from impervious surfaces. All present plants are not obligate wetland species;
understanding biological benchmarks will help determine where desired obligate species
will best perform and then help inform the inclusion of other species that will successfully
establish in the various areas of a created wetland system. Once identified, desired plant
species can be harvested and stored for planting in new areas, serving to protect the local
gene pool and reducing project costs. We recommend using this site as one of the models
for the creation of mitigation wetlands. This site functions as a natural filtration and
stormwater control system for a developed area while containing a functional community
of plants.
The old field near RPM, in Dryden, does not show evidence of ever supporting a
wetland system. Moist upland areas as well as road drainage provide a steady source and
directional flow of water through a possible wetland system. We recommend using the site
as a reference for upslope vegetation and as a possible site for the treatment of highway
runoff. The area also seems viable for wetland amphibian habitat. However, for the site to
be viable for Ambystomid salamander habitat, a mature hardwood forest would first need
o develop nearby. t