Effects and interactions of multiple variables on the species richness and diversity within
northern white-cedar (Thuja occidentalis) swamps in north central New York
Robert L. Smith II
SUNY College of Environmental Science and Forestry
Final Report to the Edna Bailey Sussman Foundation, 2015
Introduction
Many studies have been conducted concerning the factors that most affect plant species
diversity. Factors proposed have included light intensity, nutrient levels, microtopography, soil
moisture, and both natural and anthropogenic disturbance. The “humpbacked” model proposed
by J. Philip Grime suggests that stress and disturbance are the key factors in determining plant
species richness. This model contends that those communities with intermediate stress or
disturbance levels should lead to the greatest species richness (Keddy 2005). The centrifugal
organization model proposes that areas with large numbers of extreme environments will likely
lead to an overall greater species diversity (Keddy 2005).
An ecosystem where these factors and hypotheses have not been thoroughly explored and
could benefit from such an analysis is northern white-cedar swamps. These swamps are known
for both their large degree of microtopography in the form of hummocks and hollows and their
high plant diversity and rare species like ram's-head ladyslipper (Cypripedium arietinum) and
showy ladyslipper (Cypripedium reginae). This appears to be no coincidence since greater
microtopography creates an abundance of microhabitats with different levels of light, pH,
moisture, and nutrients as well as level of natural disturbance suitable to a variety of plant
species (Vivian-Smith 1997).
My research involves a two summer investigation into 10 cedar swamps on Fort Drum in
north-central New York. No prior research has been conducted in these swamps concerning the
cause of their plant diversity. These 10 swamps vary in their amount of microtopography as well
as other landscape level factors such as canopy cover, depth to water table, soil nutrients, and
levels of anthropogenic and natural disturbance. A specific disturbance that is being investigated
in this research is the effects of deer density on the plant diversity within these swamps. A 1992
report on 98 rare species concluded that a high proportion of rare lilies (40%), orchids (39%),
and dicots (56%) were adversely affected by deer herbivory (Waller & Alverson, 1997). This
makes the understory of northern white-cedar swamps particularly vulnerable since it contains
many such rare species.
The main goal of this research is to determine which attributes contribute the most to the
plant diversity in these swamps and at what levels. An additional goal is to determine the effects
of deer herbivory on the plant diversity in these swamps. The results of this study will allow
Fort Drum and other organizations to better manage these valuable natural communities and
ensure their preservation.
Methods
Plots were set up in each of the 10 northern-white cedar swamps along transects 80 m
apart at 40 m increments from the nearest road. Two main plots will be constructed from plot
center (figure 1). Vegetation plots will be 5 by 5 m quadrats with 4 small microplots and 1
medium sized microplot. Deer plots will be 2 by 10 m in size and will start 2.5 m from
vegetation plot center. In addition, the deer plots will be used for microtopography
measurements.
Figure 1: Vegetation and Deer Plots including four small understory plant microplots and one
medium sized sub-canopy microplot.
Within each of the four microplots, an inventory of understory plant species composition,
cover, stem count, and deer browse will be conducted. Within the medium sized microsite, an
inventory of sub-canopy plant species composition, cover, stem count will be conducted in the
same manner as with the understory.
Soil specific conductivity and pH at each plot will be measured by digging a hole and
immersing the sensor of a YSI Model 63 Handheld pH and Conductivity Meter. Depth to water
table will be measured by digging a hole and using a meter stick to measure the distance from the
top of the water table to the top of the hole. In order to measure microtopography, a meter stick
will be used to measure the distance between the ground and a string suspended for 10 m from
two wooden stakes 1 m in height. Estimation of deer density will take place during two summers
since deer pellets in swamps are known to take several years to decompose (H. B. Underwood,
personal communication). In the first year, each deer plot will be cleared of any deer pellets
present. During the second summer, deer pellet groups will be recorded at each deer plot along
with their position within the plot.
Preliminary Results
Mean Soil pH of these swamps were slightly acidic and ranged from 5.56 in stand 1660B
to 6.2 in stand 1900F (figure 2). The mean soil specific conductivity was lowest in stand 1660B
at 87.9 μS/cm and highest in stand 1344 at 248.75μS/cm (figure 3). The mean water table also
varied among the swamps from 25.5 cm below the surface in stand 2689 to 7.9 cm below the
surface in stand 4009B (figure 4). The degree of microtopography was compared using the mean
variance and resulted in stand 2689 having the lowest microtopography of 71.8 cm2 and stand
4009B having the highest microtopography of 167.9 cm2 (figure 5). A total of 94 plant species
were found in stands 1660B and 2033B (Table 1).
Future Work
During the second summer, a deer pellet group count will be conducted in all deer plots
that were cleared of deer pellets during the previous summer. The water table levels of all
swamp plots will be measured at the beginning and the end of the summer to determine how
much these tables fluctuate during this time period. Light availability at each cedar swamp will
be measured through the use of hemispherical photography. Lastly, plant composition, cover,
and stem count will be determined in the remaining 8 cedar swamps.
Acknowledgements
I would like to thank my major professor Dr. Donald J. Leopold for his guidance
throughout this research. I would also like to thank Jason Wagner, the chief of Natural Resources
Branch on Fort Drum, and his staff for allowing me to conduct this research and providing
datasets concerning these swamps. I am especially grateful to the Edna Bailey Sussman
Foundation for the financial support that made this research possible.
Literature Cited
Keddy, P. (2005). Putting the Plants Back into Plant Ecology: Six Pragmatic Models for
Understanding and Conserving Plant Diversity. Annals of Botany, 96, 177-189.
Vivian-Smith, G. (1997). Microtopographic Heterogeneity and Floristic Diversity in
Experimental Wetland Communities. Journal of Ecology, 85, 71-82.
Waller, D. M., & Alverson, W.S. (1997). The White-Tailed Deer: A Keystone Herbivore.
Wildlife Society Bulletin 1997, 25(2), 217-226.
Figures and Tables
Figure 2. Mean Soil pH of 10 Northern White-Cedar Swamps on Fort Drum, New York.
Figure 3. Mean Specific Conductivity of 10 Northern White-Cedar Swamps on Fort Drum,
New York.
Figure 4. Mean Water Table Depth of 10 Northern White-Cedar Swamps on Fort Drum,
New York.
Figure 5. Topography (Mean Variance) of 10 Northern White-Cedar Swamps on Fort
Drum, New York.
Table 1. Plant Composition of Cedar Stands 1660B and 2033B on Fort Drum, New York.
Scientific Name
Common Name
Abies balsamea
balsam fir
Acer rubrum
red maple
Acer saccharum
sugar maple
Actaea rubra
red baneberry
Aralia nudicaulis
wild sarsaparilla
Arisaema triphyllum
jack-in-the-pulpit
Betula alleghaniensis
yellow birch
Bidens connata
swamp beggar-ticks
Boehmeria cyclindrica
false-nettle
Caltha palustris
marsh marigold
Cardamine pennsylvatica
Pennsylvania bittercress
Carex canascens
silvery sedge
Carex disperma
soft-leaved sedge
Carex flava
yellow sedge
Carex interior
inland sedge
Carex laxiculmis
spreading sedge
Carex leptalea
bristle stalked sedge
Carex magellanica subsp irrigua
boreal bog sedge
Carex stipata
awlfruit sedge
Carex trisperma
three-seeded sedge
Chamaedaphne calyculata
leatherleaf
chelone glabra
white turtlehead
Circaea alpina
alpine enchanter's nightshade
Clintonia borealis
bluebead
Coptis trifolia
goldthread
Cornus alternifolia
alternate leaf dogwood
Cornus canadensis
bunchberry
Dalibarda repens
false violet (dewdrop)
Doellingeria umbellata
flat-topped white aster
Dryopteris intermedia
intermediate fern
Equisetum palustre
marsh horsetail
Fraxinus nigra
black ash
Galium trifidum
three petal bedstraw
Galium triflorum
sweet-scented bedstraw
Gaultheria hispidula
creeping snowberry
Gaultheria procumbens
wintergreen
Glyceria striata
fowl mannagrass
Gymnocarpium dryopteris
oak fern
Hieracium aurantiacum
orange hawkweed
Huperzia lucidula
shining clubmoss
Hydrocotyle americana
water pennywort
Ilex mucronata
mountain holly
Ilex verticillata
winterberry
Impatiens capensis
jewelweed
Iris versicolor
wild iris/blue flag
Ledum groenlandicum
bog Labrador tea
Linnaea borealis
twinflower
Scientific Name
Lonicera canadensis
Ludwigia palustris
Lycopodium obscurum
Lycopus uniflorus
Lysimachia thyriflora
Maianthemum canadense
Maianthemum racemosum
Medeola virginiana
Mimulus ringens
Mitchella repens
Mitella nuda
Oclemena acuminata
Onoclea sensibilis
Osmunda cinnamomea
Osmunda regalis
Other Bryophyte
Oxalis montana
Pinus strobus
Polygonum arifolium
Populus tremuloides
Prenanthes altissima
Prunus serotina
Pteridium aquilinum
Ranunculus recurvatus
Rhamnus alnifolia
Rosa multiflora
Rubus occidentalis
Rubus pubescens
Salix sp.
Solidago spp.
Spagnum spp.
Spiraea alba var. latifolia
Symphyotrichum puniceum
Thalictrum pubescens
Thelypteris noveboracensis
Thuja occidentalis
Tiarella cordifolia
Toxicodendron radicans
Triadenum fraseri
Trientalis borealis
Ulmus rubra
Uvularia sessilifolia
Vaccinium angustifolium
Viburnum rafinesquianum
Viola blanda
Viola renifolia
Vitis aestivalis
Common Name
American fly honeysuckle
water purslane
princess pine
bugleweed
tufted loosestrife
Canada mayflower
false Solomon's seal
Indian cucumber root
common monkey flower
partridge-berry
naked mitrewort
whorled wood aster
sensitive fern
cinnamon fern
royal fern
Moss (not sphagnum)
northern wood sorrel
eastern white pine
halberdleaf tearthumb
trembling aspen
tall rattlesnakeroot
black cherry
bracken fern
hooked crowfoot
alder-leaved buckthorn
Multiflora Rose
black raspberry
dwarf raspberry
Willow
goldenrod
spaghnum peatmoss
meadowsweet
swamp aster
tall meadow-rue
New York fern
northern white cedar
foamflower
poison ivy
Fraser's marsh St. Johnswort
starflower
slipper elm
sessileleaf bellwort
lowbush blueberry
arrowwood
sweet white violet
white (kidney shaped) violet
summer grape