Download Determining How Varying Severity of Forest Fragmentation Effect

Allegheny College
Allegheny College DSpace Repository
http://dspace.allegheny.edu
Projects by Department or Interdivisional Program
Academic Year 2016-2017
2017-05-02
Determining How Varying Severity of Forest
Fragmentation Effect Red-backed Salamander
Movement Patterns
Sadler, Abrianna
http://hdl.handle.net/10456/42792
All materials in the Allegheny College DSpace Repository are subject to college policies and Title 17
of the U.S. Code.
Determining How Varying Severity of Forest Fragmentation Effect Red-backed
Salamander Movement Patterns
By
Abrianna Sadler
Department of Environmental Science
Allegheny College
Meadville, Pennsylvania
April, 2017
Determining How Varying Severity of Forest Fragmentation Effect Red-backed
Salamander Movement Patterns
i
Table of Contents
Abstract ……………………………….…………… iii
Introduction.………………………………………. 1

Habitat Loss…………………….………… 1

Protected Areas…...…………….………… 2

Vulnerability of Plethodontid Salamanders
to Habitat Loss…………………….……... 2

Ecological Importance of Plethodontid
Salamanders…………………….……........ 3

Red-Backed Salamanders……….………. 4

Forest Fragmentation Impact on RedBacked Salamanders…………….....…….. 4

Fragmentation within Pennsylvania
Protected Areas…………………….…….. 6

Research
Objective……………………......………… 6
Methods ……………………………………………. 7

Study Site Selection ………………..…...... 7

Quantifying Movement Data …….……… 8

Procedure …………………………..…...... 8

Statistical Analysis ………………….……. 10
Results ...…………………………………………… 10
Discussion …………………………………………. 14

Conclusion ………………………………. 17
Works Cited ...……………………………………… 20
ii
Name: Abrianna Sadler
Major: Environmental Science
Thesis Committee: Dr. Casey Bradshaw-Wilson, Dr. Matt Venesky
Date: Spring, 2017
Title: Determining How Varying Severity of Forest Fragmentation Effect Red-backed
Salamander Movement Patterns
Abstract
Terrestrial salamanders occupy a wide range of habitats globally. Within the United
States, including Northeastern forests, there is an extremely high diversity and abundance of
these organisms. Typically, the most abundant species of terrestrial salamander within eastern
United States forests are Red-backed salamanders (Plethodon cinereus). These salamanders are
important to forest ecosystems because they play a key role in nutrient cycling and are indicators
of ecosystem health. One of the most devastating threats to terrestrial salamanders is habitat loss
and fragmentation due to human activity. This creates edge effects which alter and degrade
terrestrial salamander habitat. Habitat fragmentation is happening globally, even in protected
areas such as Woodcock Creek Lake Park in Crawford County, PA where Red-backed
salamanders are abundant. This study examined the impact that fragmented forests within this
protected area have on Red-backed salamander movement patterns focusing on directionality,
total distance traveled, net distance, and linearity in response to three degrees of fragmentation:
paved roads, hiking trails, and no fragmentation. Total distance moved was found to be greater in
core sites versus trail and road sites (p < 0.05) while net distance was the same for core and trail
sites but decreased for road sites (p < 0.05). No abiotic factors documented correlated with any
of the three movement patterns and only soil temperature was found to differ between the three
fragmentation treatments, with temperatures being lowest in core sites (p < 0.05). Individuals
showed no directional avoidance of either forest fragmentation although no Red-backed
salamanders attempted to cross the road or the hiking trial. Prioritizing the conservation of nonfragmented forest habitat, especially in protected areas, is essential to preserving terrestrial
salamander diversity and population and intern maintaining healthy forest ecosystems.
iii
Introduction
Habitat Loss
One of the largest threats to biological diversity and wildlife populations is habitat loss,
destruction, and fragmentation (Meffe et al. 1997). As human development exponentially
increases, ecosystems are being severely altered. These altered habitats are unable to sufficiently
provide crucial resources such as food, water, or protection and may lose the ability to harbor
organisms. Habitat loss or destruction is characterized by degradation and fragmentation (Meffe
et al. 1997). Fragmentation is the process by which a large continuous area of habitat is both
reduced in area and divided into two or more smaller segments. These remaining segments are
often isolated by highly modified or degraded landscapes. They are different from the original
ecosystem in that they have a greater amount of edge per area of habitat, the center of each
habitat fragment is closer to the edge, and large populations are divided into smaller ones
(Primack, 2010).
The edges of fragmented landscapes experience altered ecological properties coined
‘edge effects’ (Saunders, 1991). Within anthropogenically segmented forests, sites are typically
divided and surrounded by habitats with low biomass and low structural complexity such as
roads, fields, towns, or other types of human development exacerbating these edge effects. The
altered set of conditions act as a gradient; as the distance from the fragment into core forest
increases the environment becomes more suitable and stable for wildlife (Murcia, 1995). There
are three types of edge effects produced on the fragment; abiotic effects, direct biological effects,
and indirect biological effects. Abiotic effects are changes in a habitat that result from being
close to a structurally different environment. They can also come about from the inflow of
chemicals across the edge that change environmental conditions (Murcia, 1995). When a forest is
cleared, the ground becomes hotter based on its exposure to direct sunlight. Reduced canopy
cover leads to increased soil temperature during the day, decreased temperatures at night and
increased wind exposure which dries out soil and vegetation. The lack of canopy cover also
decreases leaf litter depth and downed woody debris (Murcia, 1995). Direct biotic effects involve
changes in abundance of species due to the physical conditions near the edge. Forest edges may
be occupied by species of plants and animals different from those found in the forest interior.
Indirect biotic effects are changes in species behavior and interaction such as competition or
predation (Murcia, 1995; Gehlhausen et al., 2000). The reach of these edge effects due to
1
fragmentation vary, ranging from 20 to 80 meters from the edge (Marsh & Beckman, 2004;
DeMaynadier and Hunter, 2000; Murcia, 1995).
Fragmentation within Pennsylvania Protected Areas
Protected areas are the most widespread and effective means of conservation to combat
habitat loss (Jenkins et al., 2015). They can take on many different forms such as national parks,
wilderness areas, nature reserves, and community conserved areas. Within Pennsylvania 17% of
the total land area is dedicated to terrestrial protected areas (National Gap Analysis Program,
2016). The governmental implementation of protected areas started in the early 19 century with
an initial goal to preserve large wild areas for wildlife protection and human recreation (Eagles et
al., 2002). Today protected areas have grown to occupy about 14% of the United States total land
area (National Gap Analysis Program, 2016). The purpose of these areas have also grown. They
strive to achieve the long term conservation of nature, its ecosystem services, and its associated
cultural values in addition to the original landscape preservation (IUCN, 2007). Terrestrial
protected areas help maintain ecosystem integrity, conserve biodiversity, and prevent habitat
fragmentation through the restriction of land use, extraction, and human actives (Kroner et al.,
2016; Angermeier, 2000; Ridder, 2007). Although, it has recently been suggested that protected
public lands within the United States may be too small and fragmented for sufficient preservation
of biodiversity (Haddad et al., 2015).
Protected areas contain roads and trails that are fundamental in providing access to
forested ecosystems for recreation use. They allow people to experience and study nature but
they also fragment the landscape (USDA, 2001). A study by Heilman et al. (2002) found that
protected areas do indeed contain less fragmentation than unprotected areas. Understanding the
effects roads and trails have on the forest habitat, and high importance conservation species can
help make crucial decisions on whether or not to continue protecting already protected areas, a
topic that has recently become a political controversy (Marsh & Beckman, 2004).
Woodcock Creek Lake Park is a recreational protected area located in Crawford County,
Pennsylvania with maintained trails and roads that wind throughout the park. It is the largest
recreation facility managed by the county and attracts well over 13,000 visitors during peak
season (i.e. Memorial to Labor day) (Recreational Areas, n.d.; Woodcock Creek Lake Park, PA,
n.d.).
2
Vulnerability of Plethodontid Salamanders to Habitat Loss
Plethodontid salamanders, one of the most species rich and abundant families of
salamanders within the United States, are particularly vulnerable to habitat loss and alteration
due to their environmental sensitivity. (Scheffers & Paszkowski, 2012; Burton and Likens,
1975). These lungless amphibians breathe via subcutaneous respiration; their skin must be kept
moist to permit efficient gas exchange. The high permeability of their skin, however, leaves them
susceptible to desiccation which limits their home range to moist, cool environments (Feder,
1983). It also restricts activity to times when soil moisture is high. During dry periods they are
forced to remain in saturated areas beneath woody debris, under rocks or in holes for extended
periods of time (Spotila, 1972; Spotila and Berman, 1976; Feder, 1983). Even when ecological
conditions are suitable, terrestrial salamanders risk desiccation during movement (Feder, 1983).
These specific habitat requirements in addition to their low mobility and small size make
terrestrial salamanders sensitive to disturbances such as habitat alterations (DeMaynadier &
Hunter, 1995; Semlitsch et al., 2007; Welsh & Droege, 2001).
Ecological Importance of Plethodontid Salamanders
Plethodontidae salamanders (Order: Caudata) are a vertebrate taxa that play important
ecological roles in a multitude of forest ecosystems. This is because they are diverse and often
abundant, occupying a widespread range of habitat types. Of the 400 species of salamanders
globally, which account for 8.5% of all known living amphibian species, 127 are found within
the United States (citation). Northeastern forests hold an extremely high diversity of
salamanders, with the Appalachian Mountains having more than anywhere else in the world
(Mathewson, 2006). Salamanders are an integral element of forest ecosystems; they occupy a
vital mid trophic level position and serve as indicator species of variables related to
environmental stress (Welsh and Droege, 2001; Whiles et al., 2006; DeMaynadier & Hunter,
1995; Semlitsch et al., 2007).
The population density and wide distribution of terrestrial salamanders, in addition to
their small size (ranging from 5 to 13cm), make them top predators in the forest floor foodweb
(citation). They regulate the population of invertebrates and soil micro fauna, which are too small
for birds and mammals to eat, maintaining a diverse prey population (Frasier, 1976; Jaeger,
1972). They are highly efficient at converting food into energy and are crucial in controlling leaf
3
litter breakdown and nutrient cycling on the forest floor. Sixty percent of their total consumption
is converted into biomass, increasing protein, making them a high quality prey item for snakes,
birds and small mammals (Burton & Likens, 1975; Wyman, 1998, Rooney et al.,2000, Walton et
al.,2006, Walton, 2013; Best & Welsh, 2014).
Red-backed Salamanders
The most abundant Plethodontid salamander within eastern United States forest are Redbacked salamanders (Plethodon cinereus) (Marsh et al., 2005). This generalist species is a fully
terrestrial salamander that can be found in high densities of 0.2–8.2 m−2 throughout its range
(Noel et al., 2007; Bailey, Simons, & Pollock, 2004). They breed and nest terrestrially under
rocks, woody debris, and within the soil (Lynn & Dent, 1941; Ng and Wilbur, 1995). Their home
ranges are near 13m2 for males and juveniles and 24m2 for females (Kleeberger & Werner,
1982). During wet periods, Red-backed salamanders avoid over saturated soils by escaping to the
forest floor. Characteristics that allow them to display such a wide habitat range include their
ability to survive in dry areas for a longer length of time than other salamander species and their
typically solitary and nocturnal nature, although they will forage during the day in in the leaf
litter and under cover objects staying in cool and sheltered environments (Burton, 1976; Burger,
1935). Worldwide, Red-backed salamanders have been known to climb vegetation and trees,
burrow into soil, and move horizontally throughout forest habitat (Roberts & Liebgold, 2008).
This species is extremely territorial of the cover objects they occupy and have been known to
ram the canthus rostralis of other salamanders (Gergits, 1982). In Pennsylvania, fully terrestrial
juveniles become active by the end of September, after hatching in late august (Sayler, 1966).
Overall, Red-backed are a relatively immobile species, as are most within the Plethodontidae
family.
Forest Fragmentation Impact on Red-backed Salamanders
Studies support forest fragmentations impact on Red-backed salamanders’ abundance,
genetic diversity, and potentially, movement. Consistently, a greater abundance of terrestrial
salamanders is linked to a wealth of leaf litter coverage and depth, high soil moisture, high
percentage of canopy cover, and moderate soil temperatures all of which decline within
fragmented habitat (Faccio, 2003; Regosin et al., 2005; Rittenhouse and Semlitsch, 2006).
4
Specific characteristics make them hypersensitive to direct effects produced by forest
fragmentation including their permeable skin, low dispersal ability, and constant contact with the
forest floor (Feder, 1983; Stebbins & Cohen, 1995; DeMaynadier & Hunter, 1998).
There have also been genetic implications from forest fragmentation identified in Redbacked salamanders. Following a sharp reduction in population size and inter-population
connectivity due to human activity, such as fragmentation, populations may experience loss of
rare alleles and diminished heterozygosity through genetic drift. Inbreeding can also occur,
increasing the chance offspring will be affected by recessive or damaging traits (Noel et al.,
2007). Genetic drift and inbreeding cause loss of genetic diversity and can lead to lowered fitness
and an increased risk of extinction (Reed & Frankham, 2003). One study found that populations
of Red-backed salamanders in fragmented habitats are genetically differentiated from those
living in core areas and have lowered genetic diversity (Noel et al., 2007). Since genetic diversity
leads to greater fitness and increased ability to adapt to changing environments, survival of Redbacked salamanders may be at risk (Young et al., 1996; Reed & Frankham, 2003).
Research has indicated that there are direct impacts from forest fragmentation on
terrestrial salamanders as well. When crossing over open habitat caused by fragmentation there
are increased risks of desiccation, predation, and mortality from road vehicle collisions (Carr &
Fahrig 2001; Murcia, 1995). Species with high vagility are strongly affected by these factors
because they cross open habitats more frequently (Carr & Fahrig, 2001).
The intensity of edge effects on terrestrial salamanders along different severities of
fragmentation has produced conflicting results. In a study by Marsh (2007) examining the effect
of wide ungated and narrow gated roads on salamander abundance, researchers found consistent
edge effects on ungated roads that were not detectable along gated roads (Marsh 2007).
Contrarily, other studies have found that forest roads have degraded habitat characteristics
independent of traffic intensity or public access (Marsh & Beckman, 2004; Semlitsch et al.,
2007). While Marsh et al. (2005) found evidence that gravel recreational roads and small paved
roads are minor barriers to salamander movement, showing that the smallest amount of
fragmentation may change behavior contradictory to his later findings that narrow roads create
no significant biotic changes.
Many studies examine how edge effect impacts terrestrial salamander abundance, but not
how it directly impacts their behavior (Gibbs, 1998; Marsh & Beckman, 2004; Semlitsch et al.,
5
2007; Test and Bingham, 1948; Jaeger, 1980; Taub, 1961). Few discuss movement in response to
fragmentation while most that do use abundance or displacement experiments to infer
movement. A small number of studies observe direct behavioral impacts of fragmented areas.
When Red-backed salamanders were displaced, roads significantly reduced return rates by an
average of 51% and the type of road substrate did not seem to impact movement. Return rates
were the same for open fields and forest habitat (Marsh et al., 2005). Terrestrial salamanders
within previously clear-cut habitat were found to have smaller home ranges and spent more time
under cover objects and burrowed in the soil. Studies tended to examine biological factors such
as snout vent length, body mass, and sex rather than abiotic factors (Marsh et al., 2005; Marsh &
Beckman, 2004; Cosentino & Droney, 2016).
Research Objective
The objective of this study was to determine the impact forest fragmentation within
Woodcock Creek Lake Park, a protected area in Crawford County, PA with an abundance of
Red-backed salamanders, has on Red-backed salamander movement patterns. Movements were
recorded in two categories total distance moved and net distance moved. Three fragmentation
types found throughout Woodcock Creek Lake Park were examined, hiking trails, paved roads,
and non-fragmented areas. It was hypothesized that the highest degree of fragmentation (i.e.,
paved roads) would have the most severe edge effects and a negative impact on salamander
movement. Decreased canopy cover and increased soil temp along roads would force Redbacked salamanders to take refugee within cooler soils. They would also show an avoidance of
net movement towards fragmentation. The hiking trail would still impede movement but to a
lesser degree. Non-fragmented areas would have unrestricted movement, and salamanders would
have the ability to remain above ground for longer distances due to habitat suitability increasing
total movement. They would have ideal habitat characteristics so net displacement would be
greatest in these areas allowing for a larger range.
Methods
Study Site Selection
Research was conducted at Woodcock Creek Lake Park and State Game Lands #435 in
Crawford County, PA (Figure 1). Three types of forest fragmentation were examined; paved
6
road fragmentation, gravel hiking trail fragmentation, and no fragmentation. This was assessed at
seven sites; two gravel hiking trails, two paved roads and three core sites. Previous studies have
shown edge effects do not reach past 80 m from the forest edge for Red-backed salamanders;
therefore, sites were established based on an 85 m distance between each site and any outside
type of fragmentation (Marsh & Beckman 2004; DeMaynadier and Hunter 1998). Potential site
locations were initially chosen using google maps to estimate the distance between fragmented
habitat before physically visiting Woodcock Creek Lake Park and State Game Lands #435
(Google Search, 2015). The sites were ground-truthed by manually walking to the predetermined
spots, in no particular order, and measuring distance between potential research locations and the
nearest outside type of fragmentation. Once one of the final seven sites was chosen, abiotic
factors were measured at five geographical points within the surrounding continuous forest, to
confirm that sites were ecologically similar between one another. This was done only one time
during the study and included leaf litter depth (cm), percent canopy cover, soil temperature (C),
and average number of cover objects taken within a 2-meter square at each point. Canopy cover
was measured by placing a 5 by 5 square grid on the forest floor and counting the number of
squares shaded by vegetation (PA DEP 2010). This was multiplied by four to get a canopy cover
percentage. Leaf litter depth was measured from the bare soil to the top of the uncompressed leaf
litter using a ruler. Soil temperature was determined using a soil thermometer that was inserted
into the ground at a standardized depth. This data was collected from each of the seven sites
within a 12 hour period.
Hiking trails were located off Half Rite Trail (HS1 and HS2) and road trails were off
Boat Launch Road (RS1 and RS2). Two core transects were located within Woodcock Creek
Lake Park and one in State Game Lands #435.
Figure 1: Satellite map identifying sites surveyed in Woodcock Lake Park, Crawford County PA for Plethodon Cinereus movement where CS
(core site) represents no fragmentation, RS (road site) represents most severe fragments, and HS (hiking trail site) represents less fragmentation
(Google Search 2015)
7
Quantifying Movement Data
ZQ Pigment powder (DayGlo Co. Columbus, OH) was used, which is a noninvasive
method used to track movements of small organisms in this case to mark and follow salamander
trails (Miloski, 2010). It has been determined that the powder is harmless to small mammals and
amphibians and can be repeatedly applied without negative side effects (Lemen and Freeman,
1985; Orlofske et al., 2009). This technique provides information similar to radio tracking, but
with better spatial accuracy (Eggert, 2002). Additionally, it highlights the paths traveled both
horizontally and vertically, which may be an important component of certain salamander
species’ movements including Red-backed. The use of different colored pigment powder on
multiple individuals in the same site enabled trails to be distinguishable from one another
(Eggert, 2002). This allowed for the collection of data from every individual found within a
transect in a single day. The pigment powder tracking method is inexpensive, easy to use,
applicable to all salamander sizes, and provides an exact record of movement when there is
minimal rain.
Procedure
Data collection spanned from October 8, 2016 until November 22, 2016. Percent canopy
cover, leaf litter depth, and soil temperature were taken at one point from each the left, center,
and right regions of the transect to compute average abiotic factors of that transect every time a
site was visited. These variables were recorded the same way as previously outlined. Air
temperature, obtained from AccuWeather, and hours since last rainfall were also documented. At
each site, all cover objects within the 50 by 5 meter transect were turned to search for
salamanders. The total number and the type of cover object (i.e. log or rock) were recorded.
8
Figure 2: Diagram illustrating how transects were constructed at all the sites. Each transect was 5m by 50m and at least 85m from any other
form of forest fragmentation.
When a Red-backed was found, its head direction was recorded using a compass. They
were placed in a Tupperware container for pigmentation. This was done outside of the transect to
prevent contamination. A paint brush was dipped into either the Aurora Pink or Horizon Blue
pigment powder and dusted onto the front and back of each salamander. Pigmentation was most
effective when powder was on the base of Tupperware before the salamanders were placed
inside. This allowed for coating of the underneath, sides, and top of the body as recommended by
Fellers and Drost (1989). The pigmented Red-backed was returned to the exact location of
collection and placed in the same head direction to prevent influence on direction of movement.
The cover object was placed back on top and the site was marked with a numbered flag to allow
for identification and following. Latex gloves were worn and disposed of in between each
salamander to prevent transfer of any potential pathogens. Leaf litter depth, soil temperature, and
time of pigment were also recorded at each point where a salamander was found (Miloski, 2010).
After twenty-four hours, to allow enough time for salamander movement, transects were
revisited and distance moved by each salamander was recorded (Graeter et al,. 2007; Miloski,
2010). As each Red- backed moved, the applied powder brushed off onto the soil, leaf litter,
trees, and cover objects leaving a trail. This trail was followed using an ultraviolet flashlight until
the path went into a burrow hole or disappeared, or when the salamander was found. Each
turning point was marked with a flag and then the path was traced using string. The trails each
9
individual left were mapped on graph paper using a tape measure and compass (Roe and
Grayson, 2008). Total distance traveled was determined by summing the distances individuals
moved after each change in direction. Net distance was determined by measuring from the start
to end point of each path. Linearity was computed by dividing net displacement by total path
length. From this information, how edge effect influenced salamander movement could be
qualified by comparing total distance, net distance, and path linearity of species found along the
edge versus species found within a core area (Cline & Hunter 2016).
Statistical Analysis
F-test was used to determine variance and then two sample T-test was used to test
between the three movement variables (total distance, net distances, and linearity), and the three
fragmentation treatments (road, hiking trial, and non-fragmented sites), as well as the three
movement variables and the abiotic factors of each transect (leaf litter, soil temperature, and
canopy cover). These were the average measurements found for an entire transect on a single
day. Regression plots with trendlines were produced to note any correlation among the recorded
abioitic factors and the total distance traveled, the net distance traveled, and the tortuousity of
each individual followed.
Results
One hundred and forty-one Red-backed salamanders were found within transects and
pigmented. Of the 141 salamanders, 17 pigmented trails were lost due to excessive rainfall or
wet ground cover, while 5 of the trails were successfully followed back to the initially pigmented
salamander. The remaining 120 movement trails (53 at core sites, 42 at trail sites, and 25 at road
sites) ended with individual salamanders retreating into the ground. When light rain persisted in
the 24 hour period between pigmentation and tracking, trails were still able to be successfully
followed to either the pigmented individual or into the ground. Only when heavy rain occurred
did trails become washed out and unable to follow.
The total movement of Red-backed salamanders was significantly different when
comparing the three fragmentation treatments (Figure 3A and 3B). Individual salamanders
moved a greater distance in the core sites as opposed to trail sites (p = 0.016). They also moved
more in core sites in comparison to road sites (p = 0.001). Although total distance traveled at trail
10
sites was greater than road sites, no significant difference was found between the two
fragmentation types (p = 0.10).
A
120
A
100
1
Core
6
Trail
11
16
21
26
31
36
41
46
51
Total Distance Moved (cm)
Total Distance Moved (cm)
B
500
450
400
350
300
250
200
150
100
50
0
80
B
B
60
40
20
Salamander Number
Road
0
Core
Trail
Road
Figure 3: Total distance moved between the core, trail, and road fragmentation treatment. A: Number of salamanders followed
into burrows categorized by site type. Shows total distance moved for each individual. B: Differences in average total movement
between each fragmentation treatment. A and B labels show significance between the Core, Trail, and Road in respect to total
distance moved.
When examining net movement (Figure 4A and 4B), road sites showed decreased
distances when compared to both core sites (p < 0.001) and trail sites (p < 0.008). Core sites did
not have a significantly greater average net movement than trail sites (p = 0.16).
A
A
50
A
200
150
100
50
0
1
Core
6
Trail
11
Road
16
21
26
31
36
41
46
51
Net Distance Moved (cm)
Net Distance Moved (cm)
B
250
40
B
30
20
10
Salamander Number
0
Core
Trail
Road
Figure 4: Net distance moved between the core, trail, and road fragmentation types. A: Number of salamanders followed into the
ground categorized by site type. Shows net distance moved for each individual. B: Differences in average net movement between
each site type. A and B labels show significance between the Core, Trail, and Road in respect to net distance moved.
Among the three sites, no differences were found in linearity. Percent canopy cover and
number of cover objects flipped illustrated no significant distinctions between any of the three
fragmentation types (p > 0.05). There were more overall cover objects flipped in core transects
versus trail transects and more in trail transects versus road transects. When comparing soil
temperatures (Figure 5A) and leaf litter depths (Figure 5B) of each individual Red-backed
11
followed among treatments, soil temperature was least at core sites when compared to road sites
(p < 0.001) and trail sites (p < 0.001). Trail sites had warmer soils on average, but not to a
notable degree. Leaf litter depth showed no significant difference regardless of fragmentation
type, however, when examining core and road habitats, leaf litter depth was notably less along
the road (p = 0.072).
9.4
4
B
Soil Temperature (C)
9
B
8.8
8.6
8.4
A
8.2
8
3.5
Leaf Litter Depth (cm)
9.2
7.8
3
2.5
2
1.5
1
0.5
7.6
0
7.4
Core
Trail
Core
Road
Trail
Road
Figure 5: Differences in abiotic data collected at core, trail, and road sites. A: Average soil temperature (C) recorded at each site
type B: Average leaf litter depth (cm) collected at each site type. The A and B labels show significance between the Core, Trail,
and Road in respect to soil temperature.
Regression plots comparing net distance traveled (Figure 6), total distance traveled
(Figure 6), and linearity (Figure 7) to the recorded abiotic factros revealed R2 values below one.
This data presents no statistically significant pattern between abiotic factors and movement of
Red-backed salamanders. Note that both net distance and total distance travled had positive
correlations with increase in percent canopy cover and increase in soil temperature. Both
movmenet behaviors had negative correlations with number of cover objects and leaf litter depth.
12
A
B
300
300
250
250
200
200
Total Distance Moved (cm)
Total Distance Moved (cm)
150
R² = 0.1718
Net Distance Moved (cm)
R² = 0.0899
Net Distance Moved (cm)
100
R² = 0.0972
150
100
50
50
0
0
0
2
4
6
0
20
Leaf Litter Depth (cm)
C
D
300
80
100
250
200
200
Total Distance Moved (cm)
150
R² = 0.1428
Net Distance Moved (cm)
60
300
250
Total Distance Moved (cm)
40
Percent Canopy Cover
R² = 0.0592
Net Distance Moved (cm)
R² = 0.077
100
R² = 0.0757
150
100
50
50
0
0
0
50
100
150
200
250
0
5
Number of Cover Objects
10
15
Soil Temperature (C)
Figure 6: Regression plots examining the relationship between leaf litter depth (cm) (A), percent canopy cover (B), number of
cover objects (C), and soil temperature (Celsius) (D) versus total distance and net distance moved by each Red-backed
salamander followed into the ground.
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
Linearity 0.3
R² = 0.0088
0.2
0.4
Linearity
0.3
R² = 0.017
0.2
0.1
0.1
0
0
0
1
2
3
4
5
6
0
Leaf LItter Depth (cm)
Linearity
R² = 0.2587
20
40
60
80
100
Percent Canopy Cover
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
0.5
0.5
0.4
0.2
0.4
Linearity 0.3
R² = 0.001 0.2
0.1
0.1
0.3
0
0
0
50
100
150
200
250
0
Number of Cover Objects
5
10
15
Soil Temperature (C)
Figure 7: Regression plots examining the relationship between leaf litter depth (cm) (A), percent canopy cover (B), number of
cover objects (C), and soil temperature (Celsius) (D) versus linearity of each Red-backed salamander followed into the ground.
Discussion
13
Studies have shown large dominant male Red-backed salamanders stake the most “ideal”
habitat and the territory size is congruent with the size of the individual (Holman, 2012; Mathis,
1991). It may be that these larger individuals are monopolizing core habitat forcing juveniles,
who tend to have little or no territoriality, out to the less hospitable road habitat (Jaeger et al.,
1995). In other words, decreased movements within road side habitats could occur due to the
potentially more prominent presence of juveniles. Cosentino & Droney (2016) found costly
tradeoffs between movement and desiccation. Juveniles, who are at a greater risk of desiccation
because of their bodies low surface area to volume ratio, in these areas compared to larger
territorial individuals that reside in core habitats, may be moving lesser distances overall because
of their increased risk of drying out (Grover, 1998; Cosentino & Droney, 2016). This
displacement of juveniles to poor quality habitat could have effects on both the organism’s and
ecosystem’s health. There is an increased fitness provided to individuals who have prominent
home ranges, but staking these home ranges requires energy. Total distance and net distance
moved were longer at core sites and shorter at road sites in this study. Evidence of home ranges
following similar patterns have been seen in clear cut habitats versus core habitats in a study by
Marsh & Beckman (2004) The trade-off of asserting dominance over a home range energetically
pays off, but some smaller individuals or those in non-hospitable habitats may be unable to
expend the initial costs it would take to establish a large home range (Jaeger, 1981). Diminished
home ranges within road site habitats would have negative biological effects. A study completed
in New Hampshire found that terrestrial salamanders with limited home range showed a
significantly decreased contribution to the nutrient cycling of forests floor ecosystems (Burton &
Likens, 1975). Nutrient cycling is one of the major ecological roles that terrestrial salamanders
play in the ecosystem; without their contribution, the productivity of the system would decrease.
A possible factor contributing to the displacement of the subservient individuals by those
that are dominant could be prey competition. There is a large food niche overlap between
juveniles and adults. It is presumed that P. cinereus is a superior competitor of food in soil
compared to other terrestrial salamanders; this could potentially be the same for adult versus
juvenile Red-backed (Jaeger, 1972). Previous studies have used activity as a relative measure for
foraging of terrestrial salamanders (Jaeger 1978, 1980; Pough et al., 2004). Although, amount of
prey within each fragmentation type was not recorded during this study, greater movement, like
that documented within core sites, could indicate an increase in foraging efforts, so a lower prey
14
abundance. This lower prey abundance could have contributed to larger individuals edging out
small juveniles. It would follow that individuals moving short distances along fragmented habitat
were doing so because they had sufficient prey and did not need to leave the safety of moist
refuge to forage. Although, as habitats are degraded Fraser (1976) projected that competition for
food items may increase forcing organisms to expend more energy searching for prey but that is
not what was observed in my study. A future study could examine if prey abundance increases
with degraded forest habitat at Woodcock Creek Lake Park in comparison to sites with no
fragmentation to determine if food competition is a factor impacting movement.
Movement on the forest floor increases vulnerability to predation (Jaeger, 1978). The
decrease in both total and net distance moved along road habitats may also be explained by the
increased predation characteristics associated with forest fragmentation and edge effects(Murcia,
1995; Marsh & Beckman, 2004; Turton & Freiberger, 1997). This could be tested by
documenting the automized tails of individuals captured to quantify attempted predation risk
(Roberts & Liebgold, 2008).
Numerically, trail sites had more leaf litter and medium canopy cover which may allow
individuals residing there to avoid the desiccation that would normally threaten them due to the
increased soil temperatures seen at this type of fragmentation in this study. Red-backed
salamanders may be able to move out from under refuge because a high number of cover objects
shade and maintain cool temperature retreats. Leaf litter and cover objects also hold moisture
well, decreasing risk of drying out (Woolbright & Martin, 2014). These habitat characteristics
could enable Red-backed salamanders residing near trail fragmentation to consistently travel
short distances over multi-day periods, allowing longer net distance movements that mitigate the
negative effects of fragmentation on total distance moved. This is also supported by the negative
relationship seen in this study between both movement variables and leaf litter depth (cm) and
both movement variables and number of cover objects.
The lack of correlation in this study between movement patterns including total distance
moved, net distance moved, and linearity, in correlation to abiotic edge effects of percent canopy
cover, number of cover objects, and leaf litter depth aligns with the consistently concluded idea
that ability to retain water, and therefore soil moisture and temperature, is the major
characteristic influencing Plethodontid movement. As stated earlier, soil moisture has been
shown to be a key characteristic affecting Red-backed salamander population and latency (Marsh
15
& Beckman, 2004; Yeager 1980) and studies suggest that soil moisture is most likely a key
determinant of movement as well. Others state that cool soil temperatures have more of an
impact on movement behavior due to its larger role in potential desiccation (Rothermel &
Luhring, 2005; Keen, 1984). Although this study did not find any correlation between soil
temperature and either net distance or total distance traveled, it demonstrated that temperatures
were significantly higher along road sites versus both core and trail sites. This temperature
difference aligns with net movement, where road fragmented sites showed decreased net
displacement when compared to trail and core habitat. These findings, in conjunction with the
confounding literature suggest soil temperature and soil moisture are important aspects that
needs to be studied further in future research when examining movement behavior.
Red-backed salamanders are found to be either absent from the habitat or remain within
soil to maintain amiable temperatures when soil temperatures are below 5 or above 25 degrees
Celsius (Taub, 1961). Within this study, soil temperatures remained within the range of known
abundance with week relationship found between movement variables and soil temperatures.
This may be due to the fact that temperatures were recorded during the day and not at night,
when temperatures are likely to drop. This is also when Red-backed salamanders are most active.
Nighttime soil temperatures could have a stronger correlation with the movement variables than
daytime due to the nocturnal nature of this terrestrial salamander.
A weakness of this study was the time constraint resulting in an incapability to record soil
moisture. From observations made in the field, habitat near road fragment appeared to have
severely inconsistent moisture levels. Following bouts of rain, edge habitat retained excessive
amounts of soil moisture, with puddling in areas for over 24-hour periods while sites within
forest appeared to steadily wet and drain. RBS cannot forage in extremely dry soils nor can they
do so in inundated soils (Taub, 1961). Soil moisture noted along road side habitat (dry to overtly
saturate) inhibits salamander movement which aligns with this study’s findings of decreased
movement along fragmentation and increased along core habitat. In future studies, soil moisture
should be documented to test correlation between movement variables.
It was believed individuals would avoid traveling in the direction of fragmentation due to
its assumed degraded habitat quality. Physical characteristics associated with fragmentation
create an unfavorable habitat for terrestrial salamanders decreasing abundance among
fragmented habitat, specifically, volume of cover objects, soil temperature, percent canopy
16
cover, leaf litter depth, and soil moisture (Grove, 1998; Bobka et al., 1981). Within this study,
there was a lack of variation in percent canopy cover, cover objects, or leaf litter depth between
treatment types. The consistent quality of these characteristics may prevent organisms from
delineating among fragmented and non-fragmented areas within Woodcock Creek Lake Park.
Habitat alterations associated with fragmentation were not strongly differentiated so individuals
are not avoiding fragmentation during short term movement. Long term movement studies,
covering multiday periods, sampling at increasing distances from fragmentation may express the
typical gradient of increasing abiotic factors away from fragment and a net movement away from
fragmentation (Chen et al., 1995).
One of the largest limitations of this study was the inability to identify individuals as
recaptured. It is unknown whether the same organisms were captured each time the site was
visited or if new salamanders were found and pigmented each time. Knowing this could provide
multi-day movement data of individuals as well as verify or expand the sample size of the study.
This type of knowledge should be addressed in future research. A noninvasive technique to do
this is through computer vision software. Through photographs taken of the salamanders as they
are found, the software will allow researchers to identify Red-backed salamanders by their
specific coloring and markings. Computer identification was attempted during this study
although it was unsuccessful at identifying individuals. In the future for greatest success,
salamanders should be rinsed using either rain or DI water and then placed in a shadowed boxed
to prevent glare from the sun. By standardizing the background each photo is taken and the
camera it is take with, the percent error of this computer vision software greatly decreases. This
is an extremely user friendly software proven to be ideal for the sample sizes of this type of study
(Gamble et al. 2008).
A future study branching from results found at Woodcock Creek Lake Park would
continue to look at the impact forest fragmentation has on Red-backed movement using
fluorescent pigment powder. Photo ID software would be used to identify individuals and collect
information about home range size in addition to movement data. Soil moisture and soil
temperature would be documented as well as snout vent length and total length. This would help
determine if adults are more common in the core habitat and if juveniles are potentially more
abundant near fragmented habitat.
17
Conservation
With the impact that fragmentation has on Red-backed salamander movement patterns, it
is likely that this fragmentation will affect the movement of specialist species who typically have
a limited habitat and low tolerance to altered environmental conditions (Scheffers & Paszkowski,
2012). Because of the risks associated with fragmentation for terrestrial salamanders, protection
of road-less areas is an important and effective conservation strategy (Semlitsch, 2000; Blaustein
et al., 2000; Gucinski et al., 2001). Protected areas have more road less spaces with less habitat
fragmentation. To preserve terrestrial salamanders, protection of areas like Woodcock Creek
Lake Park is both vital and most effective since these areas already have larger un-inhibited
habitats compared to other public and private lands (Haddad et al., 2015; Gucinski et al., 2001).
It is important to note that during this study it was difficult to find patches of habitat greater than
or at least eighty meters apart, which is the furthest distance edge effects are determined to affect
for this species. Research had to extend out to nearby state game lands to find additional
uninterrupted core sites with eighty meters of buffer on all sides. Woodcock Creek Lake Park is
a protected area and even then it was challenging to find habitat that was not effected by some
degree of fragmentation. This trend has been seen in other national forests identifying a need for
stringent protection of these areas (Gucinski et al., 2001). It has been suggested that traffic
density plays a large role in the impact of edge effects for organisms (Fahrig et al., 1995; Hels &
Buchwalk 2001; Mazerolle, 2004). Woodcock Creek Lake Park is a relatively low traffic zone,
with less than 15,000 visitors during peak summer season. The impacts of forest fragmentation
on Red-backed movement may be increased and exacerbated during peak season and movement
may be more affected at larger well-known parks that attract a greater amount of activity. These
two findings combined suggest that the current conservation of road less areas in national parks,
even though it is greater than non-protected lands, is still not sufficient. Management practices
should focus on creating road ways and hiking trails that maximize the inner forest habitat
between anthropogenic transportation pathways to decreases the amount of fragmentation and
net impact of traffic density on edge effects associated with forest fragmentation.
This study supports the claim that habitat destruction and fragmentation negatively
impacts movement of Red-backed salamanders. This coupled with their declining populations
and lack of abundance along fragmented habitat, both documented in the literature, demonstrates
their need to be a focus of conservation. Decreasing the number of individuals within these areas
18
as well as limiting the range they affect within their habitat could impede the keystone predatory
role they play in the forest floor ecosystem. Terrestrial salamanders mainly feed on soil micro
fauna and invertebrates. Their high density in northeaster forests makes them major contributors
to the forest floor food web and regulators of soil micro fauna and invertebrates (Burton &
Likens, 1975; Hulse et al., 2001). For the same reasons, they are essential and abundant prey for
larger predators (Frasier, 19768; Jaeger, 1972). A notable decrease in terrestrial salamander
populations would cause cascading trophic effects to the forest floor detrital food chain and
nutrient break down (Walton, 2013; Walton et al., 2016).
This type of amphibian population reduction and loss is happening globally. Earth is
facing one of its largest mass extinctions (Wake & Vredenburg, 2008). Biodiversity is declining
at increasing rates, disproportionately so in amphibian populations and species (Houlahan et al.,
2000; Alford et al., 2001). Over 40% of amphibian species are identified by the IUCN as
threatened or endangered (Bishop et al., 2012). This is happening due to a combination of factors
including pollution, presence of exotic species, overexploitation, climate change, disease, and
most significantly, alteration of habitat including habitat fragmentation and degradations (Collins
& Storfer, 2003). Prioritizing the conservation of non-fragmented forest habitat, especially in
protected areas, is essential to preserving terrestrial salamander population and diversity and, in
turn, maintaining healthy forest ecosystems.
19
Works Cited
Alford, R.A., Dixon, P.M. & Pechmann, J.H.K. (2001). Global amphibian population declines. Nature
414, 449-500.
Angermeier, P. L. (2000). The natural imperative for biological conservation. Conservation Biology
14, 373-381.
Bailey LL, Simons TR, Pollock KH (2004) Comparing population size estimators for Plethodontid
salamanders. Journal of Herpetology 38, 370–380.
Best, M. L. & Welsh Jr., H. H. (2014). The trophic role of a forest salamander: Impacts on
invertebrates, leaf litter retention, and the humification process. Ecosphere 5(16).
Bishop, P. J., Angulo, A., Lewis, J. P., Moore, R. D., Rabb, G. B., & Garcia Moreno, J. (2012). The
Amphibian Extinction Crisis – What will it take to put the action into the Amphibian
Conservation Action Plan? S.A.P.I.E.N.S. 5(2), 97 -111.
Blaustein, A.R., Chivers, D.P., Kats, L.B., & Kiesecker, J.M. (2000). Effects of ultraviolet radiation
on locomotion and orientation in roughskin newts (Taricha granulosa). Ethology 106,
227–
234.
Bobka, M. S., Jaeger, R. G., & McNaught, D. C. (1981). Temperature dependent assimilation
efficiencies of two species of terrestrial salamanders. Copeia 1981(2), 79-83.
Burger, J. (1935). Plethodon cinereus (Green) in Eastern Pennsylvania and New Jersey. The
American Naturalist 69(725), 578-586.
Burton, T., & Likens, G. (1975). Energy Flow and Nutrient Cycling in Salamander Populations in the
Hubbard Brook Experimental Forest, New Hampshire. Ecology 56(5), 1068-1080.
20
Carr L. W., & Fahrig, L. (2001). Effect of road traffic on two amphibian species of differing vagility.
Conservation Biology 15, 1071–1078.
Chen, J., Franklin, J. F., & Spies, T. A. (1995). Growing-Season Microclimatic Gradients from
Clear-cut Edges into Old-Growth Douglas-Fir Forests. Ecological Applications 5(1), 74–86.
Cline, B. B. and Hunter, M. L. (2016), Movement in the matrix: substrates and distance-to-forest
edge affect post metamorphic movements of a forest amphibian. Ecosphere 7: n/a, e01202.
Collins, J., & Storfer, A. (2003). Global Amphibian Declines: Sorting the Hypotheses. Diversity and
Distributions, 9(2), 89-98.
Cosentino, B. J. & Droney, D. C. (2016). Movement behavior of woodland salamanders is repeatable
and varies with forest age in a fragmented landscape. Animal Behaviour 121, 137-146.
DeMaynadier, P. G. & Hunter, M. L. (1995). The relationship between forest management and
amphibian ecology: a review of the North American literature. Environmental Revolution 3,
230-261.
DeMaynadier, P. G. & Hunter, M. L. (1998). Effects of silvicultural edges on the distribution and
abundance of amphibians in Maine. Conservation Biology 12, 340-352.
DeMaynadier, P. G., & Hunter Jr, M. L. (2000). Road effects on amphibian movements in a forested
landscape. Natural Areas Journal 20(1), 56-65.
Eagles, P. F. J., McCool, S. F., & Haynes, C. D. (2002). Sustainable tourism in protected areas.
Prepared for The World Conservation Union.
Eggert, C. (2002) Use of fluorescent pigments and implantable transmitters to track a fossorial toad
(Pelobates fuscus). Herpetological Journa, 12(2), 69-74.
21
Faccio, S. (2003). Post breeding Emigration and Habitat Use by Jefferson and Spotted Salamanders
in Vermont. Journal of Herpetology 37(3), 479-489.
Fahrig, L., Pedlar, J. H., Pope, S. E., Taylor, P. D., & Wegner, J. F. (1995). Effects of road traffic on
amphibian density. Biological Conservation 73, 177-182.
Feder, M. E. (1983). Integrating the ecology and physiology of plethodontid salamanders.
Herpetologica 39, 291-310.
Fellers, G. M., & Drost, C. A. (1989). Fluorescent powder: a method for tracking reptiles.
Herpetological Review 20, 91-92.
Fraser, D. F. (1976). Empirical evaluation of the hypothesis of food competition in salamanders of
the genus Plethodon. Ecology 57, 459-471.
Gamble, L., Ravela, S. & McGarigal, K. (2008) Multi-scale features for identifying individuals in
large biological databases: an application of pattern recognition technology to the marbled
salamander Ambystoma opacum. Journal of Applied Ecology 45, 170–180.
Gehlhausen, S. M., Schwartz, M. W., & Augspurger, C. K. (2000). Vegetation and microclimatic
edge effects in two mixed-mesophytic forest fragments. Plant Ecology 147(1), 21–35.
Gergits, W. F. (1982). Interference Competition and Territoriality between the Terrestrial
Salamanders Plethodon cinereus and Plethodon shenandoah. M.S. Thesis, State University of
New York at Albany.
Gibbs, J.P. (1998). Amphibian Movements in Response to Forest Edges, Roads, and Streambeds in
Southern New England. Journal of Wildlife Management 62(2), 584-589
Graeter, G. J., Roethermel, B. B., & Gibbons J. W. (2007). Habitat selection and movement of pondbreeding amphibians in experimentally fragmented pine forests. Journal of Wildlife
22
Management 72, 473-482.
Grover, M. C. (1998). Influence of cover and moisture on abundance of the terrestrial salamanders
Plethodon cinereus and Plethodon glutinosus. Journal of Herpetology 32(4), 489-497.
Gucinski, H., Furnis, M. J., Zimer, R. R., & Brookes, M. H. (2001). Forest roads: a synthesis of
scientific information. General technical report PNW-GTR-509. U. S. Forest Service
Portland, Oregon.
Haskell, D. (2000). Effects of Forest Roads on Macroinvertebrate Soil Fauna of the Southern
Appalachian Mountains. Conservation Biology 14(1), 57-63.
Haddad, N. M., Brudvig, L. A., Clobert, J., Davies, K. F., Gonzalez, A., Holt, R. D., Lovejoy, T. E.,
Sexton, J. O., Austin, M. P., Collins, C. D., Cook, W. M., Damschen, E. I., Ewers, R. M.,
Foster, B. L., Jenkins, C. N., King, A. J., Laurance, A. J., Levey, D. J., Margules, C. R.,
Melbourne, D. J., Nicholls, A. O., Orrock, J. L., Song, D. X., & Townshend, J. R. (2015).
Habitat fragmentation and its lasting impact on Earth’s ecosystems. Science Advances 1:
e1500052.
Heilman, G. E., Jr, J. R. Strittholt, N. C. Slosser, and D. A. Dellasala. (2002). Forest fragmentation of
the conterminous United States: assessing forest intactness through road density and spatial
characteristics: forest fragmentation can be measured and monitored in a powerful new way
by combining remote sensing, geographic information systems, and analytical software.
BioScience 52, 411-422.
Hels, T., & Buchwald, E. (2001). The effect of road kills on amphibian populations. Biological
Conservation 99, 331-340.
Holman, J. A. (2012). The amphibians and reptiles of Michigan a Quaternary and Recent faunal
adventure. Detroit, MI: Wayne State University Press.
Houlahan, J.E., Findley, C.S., Schmidy, B.R., Meyer, A.H. & Kuzmin, S.L. (2000). Quantitative
23
evidence for global amphibian declines. Nature 404, 752-755.
Hulse, A.C., McCoy, C.J., & Censky, E.J. (2001). Amphibians and Reptiles of Pennsylvania and the
Northeast. Cornell University Press, Ithaca, New York
Jaeger, R. G., & Barnard, D. E. (1981). Foraging Tactics of a Terrestrial Salamander: Choice of Diet
in Structurally Simple Environments. The American Naturalist 117(5), 639-664.
Jaeger, R. G. (1972). Food as a limited resource in competition between two species of terrestrial
salamanders. Ecology 55, 535-546.
Jaeger, R. G. (1978). Plant climbing by salamanders: periodic availability of plant-dwelling prey.
Copeia 1978, 686-691.
Jaeger, R. G. (1980). Microhabitats of a Terrestrial Forest Salamander. Copeia 1980(2), 265-268.
Jaeger, R. G. (1981). Dear enemy recognition and the costs of aggression between salamanders.
American Naturalist 117, 962e974.
Jaeger, R. G., Wicknick, J. A., Griffis, M. R., and Anthony, C. D. (1995). Socioecology of a
terrestrial salamander—juveniles enter adult territories during stressful foraging periods.
Ecology 76, 533–543.
Jenkins, C. N. (2015). United States protected lands mismatch biodiversity priorities. Proceedings of
the National Academy of Sciences 112(6), 5081-5086.
Keen, W.H. (1984). Influence of moisture on the activity of a plethodontid salamander. Copeia 1984,
684-688.
Kleeberger, S. R., and Werner, J. K. (1982). Home range and homeing behavior of Plethodon
cinereus in northern Michigan Copea 1982, 409-415
Kleeberger, S. R. & J. K. Werner. (1983). Post-breeding migration and summer movement of
Ambystoma maculatum. Journal of Herpetology 17,176–177.
24
Kroner, G., Krithivasan, R., & Mascia, M. B. (2016). Effects of protected area downsizing on habitat
fragmentation in Yosemite National Park (USA). Ecology and Society 21(3).
Lemen, C., & Freeman, P. (1985). Tracking Mammals with Fluorescent Pigments: A New
Technique. Journal of Mammalogy 66(1), 134-136.
Lynn & Dent. (1941). Notes on Plethodon cinereus and Hemidactylium seutatum on Cape Cod.
Copeia 2, 113-114.
Mathis, A. (1991). Territories of male and female terrestrial salamanders: costs, benefits, and
intersexual spatial association. Oecologia 86: 433-440.
Marsh, D. M. (2007). Edge Effects of Gated and Ungated Roads on Terrestrial Salamanders. Journal
of Wildlife Management, 7(3), 389-394.
Marsh, D., & Beckman, N. (2004). Effects of Forest Roads on the Abundance and Activity of
Terrestrial Salamanders. Ecological Applications 14(6), 1882-1891.
Marsh, D., Milam, G., Gorham, N., & Beckman, N. (2005). Forest Roads as Partial Barriers to
Terrestrial Salamander Movement. Conservation Biology 19(6), 2004-2008.
Mathewson, B. G. (2006). Differences in eastern red-backed salamander (Plethodon cinereus)
populations in hemlock-dominated and mixed deciduous forests in north-central
Massachusetts. The Graduate School of Arts and Sciences of Harvard University. Cambridge,
Massachusetts.
Mazerolle, M. J. (2004). Amphibian road mortality in response to nightly variations in traffic
intensity. Herpetologica 60, 45-53.
Meffe, G. K., & Caroll C.R. and contributors. (1997). Principles of Conservation Biology. (2nd ed).
25
Sunderland, Ma.: Sinauer.
Miloski, S. (2010). Movement Patterns and Artificial Arboreal Cover Use of Green Salamanders
(Aneides aeneus) in Kanawha County, West Virginia. Marshal University Thesis, Dissertation
and Capstone.
Murcia, C. (1995). Edge effects in fragmented forests: implications for conservation. Trends in
Ecology & Evolution 10(2), 58–62.
National Gap Analysis Program (2016, August) retrieved from (National Gap Analysis Program,
2016)
Ng, M. Y., & Wilbur, H. W. (1995). The cost of brooding in Plethodon cinereus. Herpetologica
51(1), 1-7.
Noel, S., Oullet, M., and Galois, P. (2007). Impact of urban fragmentation on the genetic structure of
the eastern red backed salamander. Conservation Genetics 8, 599-606.
Orlofske, S. A., Grayson, K. L., & Hopkins, W. A. (2009). The Effects of Fluorescent Tracking
Powder on Oxygen Consumption in Salamanders Using Either Cutaneous or Bimodal
Respiration. Copeia 2009, 623-627
PA DEP. 2010. Riparian Forest Buffer Guide. Document number: 394-5600-001.
Pough, F.H., R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky, and K.D. Wells. 2004.
Herpetology 3
rd
Edition, pp. 431. Pearson Prentice Hall. Saddle River, New Jersey.
Primack, R. B. (2010). Essentials of conservation biology. Sunderland (Massachusetts): Sinauer
Associates.
Recreational Areas (n.d.) Retrieved from www.usa.gov/recreation.
26
Reed, D. H. & Frankham, R. (2003) Correlation between fitness and genetic diversity. Conservation
Biology 17, 230–237
Regosin, J. V., Windmiller, B. S., Homan, R. N., & Reed, J. M. (2005). Varriaiton in Terrestrial
Habitat use by Four Pool-breeding Amphibian Species. Journal of Wildlife Management 69,
1481-1493.
Ridder, B. (2007). An exploration of the value of naturalness and wild nature. Journal of Agricultural
and Environmental Ethics 20, 195-213.
Rittenhouse, T. A. G. & R. D. Semlitsch. (2006). Grasslands as movement barriers for a forestassociated salamander: migration behavior of adult and juvenile salamanders at a distinct
habitat edge. Biological Conservation 131,14–22.
Roberts, A. & Liebgold, E. B. (2008). The effects of perceived mortality risk on habitat selection in a
terrestrial salamander. Behavioral Ecology 19, 621-626.
Roe, A., & Grayson, K. (2008). Terrestrial Movements and Habitat Use of Juvenile and Emigrating
Adult Eastern Red-Spotted Newts, Notophthaltnus viridescens. Journal of Herpetology 42(1),
22-30.
Rooney, T. P., Antolik, C., & Moran, M. D. (2000). The impact of salamander predation on
collembola abundance. Proceedings of the Entomological Society of Washington 102, 308–
312.
Rothermel, B. B., & Luhring, T. M. (2005). Burrow availability and desiccation risk of mole
salamanders (Ambystoma talpoideum) in harvested versus unharvested forest stands. Journal
of Herpetology 39, 619e626.
Sayler, A. (1966). The reproductive ecology of the red-backed salamander, Plethodon cinereus, in
27
Maryland. Copeia 1966, 183-193.
Saunders, D.A., Hobbs, R.J., & Margules, C. R. (1991) Conservation Biology 5,18-32
Scheffers, B. R., & Paszkowski, C. A. (2012). The effects of urbanization on north American
amphibian species: Identifying new directions for urban conservation. Urban Ecosystems
15(1), 133-147.
Spotila, J. R. (1972). Role of temperature and water in the ecology of lungless salamanders. Ecology
Monography 42, 95-125.
Spotila, J. R. & Berman, E. N. (1976). Determination of skin resistance and the role of skin in
controlling water loss in amphibians and reptiles. Comparative Biochemical Physiology 55A,
407-411.
Stebbins, R.C. & Cohen, N. W. (1995). A natural history of amphibians. Princeton University Press,
Princeton, NJ. 316 p.
Taub, F. (1961). The Distribution of the Red-Backed Salamander, Plethodon C. Cinereus, within the
Soil. Ecology 42(4), 681-698.
Test, F., & Bingham, B. (1948). Census of a Population of the Red-Backed Salamander (Plethodon
cinereus). The American Midland Naturalist 39(2), 362-372.
Turton, S. M., & Freiburger, H. J. (1997). Edge and aspect effects on the microclimate of a small
tropical forest remnant on the Atherton Tableland, Northeastern Australia. Tropical Forest
Remnants: Ecology, Management and Conservation of Fragmented Communities. University
of Chicago Press, Chicago, Illinois, 45–54.
Wake, D. B., & Vredenburg, V. T. (2008). Are we in the midst of the sixth mass extinction? A view
from the world of amphibians. Proceedings of the National Academy of Sciences,
28
105(Supplement 1), 11466–11473.
Walton, B. M. (2013). Top-down regulation of litter invertebrates by a terrestrial salamander.
Herpetologica 69, 127–146.
Walton, B. M., Tsatiris, D., & Rivera-Sostre, M. (2006). Salamanders in forest-floor food webs:
Invertebrate species composition influences top–down effects. Pedobiologia 50, 313–321.
Welsh, H., & Droege, S. (2001). A Case for Using Plethodontid Salamanders for Monitoring
Biodiversity and Ecosystem Integrity of North American Forests. Conservation Biology
15(3), 558-569.
Whiles, M. R., Lips, K. R., Pringle, C. M., Kilhara, S. S., Bixby, R. J., Brenes, R., Connelly, S.,
Checo Colon Gause, J., Hunte-Brown, M., Huryn, A. D., Montgomery, C., & Peterson, S.
(2006). The effects of amphibian population declines on the structure and function of
Neotropical stream ecosystems. Frontiers in Ecology and the Environment 4, 27-34.
Woodcock Creek Lake Park, PA (n.d.) Retrieved from
https://www.recreation.gov/recreationalAreaDetails.do?contractCode=NRSO&recAreaId=411
Wyman, R. L. (1998). Experimental assessment of salamanders as predators of detrital food webs:
effects on invertebrates, decomposition and the carbon cycle. Biodiversity & Conservation
7(5), 641–650.
Young, A., Boyle, T., & Brown, T. (1996) The population genetic consequences of habitat
fragmentation for plants. Trends Ecological Evolution 11, 413–418.
29