Funding Source:
U.S.D.A. Forest Service
Utah Division of Wildlife Resources
Utah Wilderness Association
Project Location: Uinta Mountains of northeastern Utah
Project Duration: September 1990 - December 1994
Investigators:
Christina Hargis
John A. Bissonette
Technicians:
Peter Lortz
Rob Rood
The Ph.D. thesis was written as a series of three papers. The abstract for
each are given below.
(1) THE BEHAVIOR OF LANDSCAPE METRICS COMMONLY USED IN THE STUDY
OF HABITAT FRAGMENTATION
Abstract:
Landscape metrics have been developed for quantifying various aspects of
landscape pattern, and several of these have been applied to studies of habitat
fragmentation. A meaningful interpretation of landscape metrics is only possible
when the limitations of each measure are fully understood, the range of
attainable values is known, and the user is aware of potential shifts in
the range of values due to characteristics of landscape patches. To examine
the behavior of landscape metrics, I generated artificial landscapes that
mimicked fragmentation processes while controlling the size, shape, and placement
of disturbance patches. I created nine series of increasingly fragmented
landscapes that differed from one another in the size or shape of patch used
to represent disturbance and in the way disturbance was allowed to increase,
and used these landscapes to investigate edge density, contagion, mean nearest
neighbor distance, mean proximity index, perimeter-area fractal dimension,
and mass fractal dimension. Most of the metrics provided unique information
about an aspect of landscape pattern, but contagion and edge density were
highly correlated, as were mass fractal dimension and the amount of disturbance.
Correlations among metrics increased when disturbance growth was through
buffered patches, because buffers restricted the proportion of disturbance
on the landcape to less than 0.40, and many of the metrics were
linearly-associated with increasing disturbance up to 0.40. None of the measures
were able to distinguish landscape patterns of dispersed versus aggregated
patches. The attainable values of all measures were altered by either patch
size or shape, and in some cases, by both attributes. I summarize the utility
of each metric in providing information about habitat fragmentation.
(2) THE INFLUENCE OF FOREST FRAGMENTATIONON AMERICAN MARTEN
POPULATIONS
Abstract:
I investigated the effects of forest fragmentation on American marten (Martes
americana) by evaluating differences in marten densities across 18 study
sites that varied in landscape heterogeneity due to the combined effects
of natural openings and timber harvest clearcuts. The 9-km2 sites were located
in mature forests in the Uinta Mountains of northern Utah, and open areas
occupied 2-42% of each site. I proposed three possible responses of marten
populations to increases in fragmentation: 1) a linear negative decline based
on habitat loss; 2) an initial positive response related to the added diversity
and abundance of small mammals associated with clearcuts and meadows; and
3) an accelerated decline due to the combined effects of landscape pattern
and habitat loss. I used ERDAS, a raster-based GIS, to classify the landscape
images into 2-attribute maps representing forest and openings, and quantified
fragmentation using five measures: the percent of each site in open areas,
edge density, mean proximity index for open patches, mean nearest neighbor
distance between open patches, and mass fractal dimension of the forest matrix.
Within each site, I estimated marten abundance through live-trapping, estimated
small mammal densities through snap-trapping, and collected data on forest
structure. I found a significant negative correlation of marten captures
to the combined effects of loss of forest habitat, as measured by the percent
of each site in open areas and an increase in the proportional representation
of snags in the overstory (P less than 0.05). The graphed relationship of
marten captures and percent of site in openings suggested a possible threshold
when open areas exceeded 20% of the landscape. Absence of marten occurred
earlier than predicted by direct loss of habitat, implying additive effects
of landscape pattern. Mean proximity index, which quantifies patch isolation
based on the size and distance between open areas, was the strongest correlate
with marten captures. Marten were not found in landscapes where patches were
large and closely situated, and the combined effects of patch proximity and
snag abundance explained more variation in marten captures than any other
model examined (R2 = .59). I found no evidence of a positive response to
low levels of fragmentation. Small mammal densities were significantly higher
in clearcuts than in forests (P less than 0.01), but marten captures were
not correlated with the increase in prey abundance or biomass associated
with clearcuts. Conservation efforts for the marten must consider not only
the structural aspects of mature forests, but the landscape pattern in which
the forest occurs. I recommend that timber harvest blocks be aggregated to
reduce forest edge and maintain maximum area in forest interior.
(3) LANDSCAPE -LEVEL EFFECTS OF TIMBER HARVESTS ON SMALL MAMMAL
POPULATIONS IN SPRUCE-FIR FORESTS
Abstract:
Small mammal communities are affected by changes in vegetation and habitat structure resulting from clearcut timber harvests, but the effects of multiple clearcut blocks at the landscape scale have not been studied. I conducted a small mammal survey within a series of 9 km2 landscapes containing varying proportions of forest and open areas to examine effects of landscape pattern on small mammal populations. The broad scale of this study also provided a large and geographically-disjunct set of clearcut blocks and forest stands for comparing small mammal communities between these habitats. I surveyed small mammal populations over a 7-week period between 22 July and 8 Sept, 1992, using 1,200 trap nights per study site, and captured 14 species of small mammals. The five most commonly-trapped species were the southern red-backed vole (Clethrionomys gapperi), deer mouse (Peromyscus maniculatus), Uinta chipmunk (Eutamias umbrinus), least chipmunk (Eutamias minimus), and shrew (Sorex spp). Capture rates of southern red-backed vole, the most frequently-captured species in mature forests, declined with loss of forest habitat, but the decline was greater than predicted from a null model of capture rates based on habitat loss alone. Landcape pattern appeared to serve as an additive effect contributing to lower captures of red-backed voles in landscapes with high edge density, little forest interior, and large, open areas in close proximity. In contrast, these landscape patterns were associated with increased capture rates of deer mice, which occurred in greatest numbers in clearcuts and in landscapes with high juxtaposition of open areas with forests. The Uinta chipmunk was the only other species captured in sufficient numbers to analyze statistically, and I found no change in capture rates with fragmentation. At the scale of individual cut blocks and habitat comparisons, I found greater species richness in mature forests, but higher overall capture rates in clearcut blocks. I concluded that land managers must be aware not only of the effects of individual cut blocks, but of the larger scale effects of cut blocks on landscape pattern and small mammals, as well as the potential influences on larger species for whom the small mammals serve as prey. I recommend aggregated rather than dispersed patterns of clearcuts so that a greater proportion of the landscape can be maintained in forest interior habitat for species that are sensitive to habitat area and edge.
Funding Source:
U.S.Bureau of Reclamation
Utah Department of Transportation
Utah Division of Wildlife Resources
Project Location: Jordanelle Reservoir area, Utah
Project Duration: September 1993 - September 1996
Investigators:
John A. Bissonette
Mark Lehnert
Technicians: Christine Vogel
Gabe Bissonette
Karen Griffiths
Rerouting highways to accommodate construction of the Jordanelle Reservoir
in northeastern Utah caused a dramatic increase in vehicle collisions with
mule deer (Odocoileus hemionus). I evaluated the effectiveness of a new system
of highway crosswalk structures installed to reduce deer losses and preserve
seasonal migrations. In addition, I constructed computer simulation models
to investigate how highway mortality has impacted the Jordanelle deer
population.
The crosswalk system restricted deer crossings to specific, well-marked areas
along highways where motorists could anticipate them. Subsequent to installation,
mortality declined 42.3% and 36.8% along a four-lane and two-lane highway,
respectively. I was unable to statistically demonstrate that observed mortality
reductions were a direct result of the crosswalk system. The potential
applicability of the structures, however, should not be dismissed. Reduced
deer use of the highway right-of-way (ROW), the apparent maintenance of migratory
behavior, and observations of animals crossing within crosswalk boundaries
indicate the system warrants further testing. Lack of motorist response to
crosswalk warning signs, the tendency for foraging deer to wander outside
crosswalk boundaries, and the ineffectiveness of ROW escape gates contributed
to most treatment area mortalities. I offer design modifications that address
these shortcomings.
Four years of field data revealed that highway mortality at Jordanelle was inversely density-dependent, removed between 5.6% and 17.4% of the population each year, and disproportionately impacted bucks. I incorporated this information into 3 competing simulation models in which highway losses operated in a strictly additive, partially compensatory, or strictly compensatory manner. The partial compensation model most closely tracked observed population dynamics, suggesting that highway losses were not completely offset by reductions in other mortality sources. Highway mortality apparently worsened a population crash initiated by severe winter conditions, and may be slowing the recovery. The disproportionate loss of bucks along roads altered sex ratios of simulated populations. Mitigative efforts should target road-kill reductions >60% to avoid population declines predicted by the partial compensation model. Annual variation in demographic parameters offset the impacts of highway mortality at high population levels. At low population levels, however, highway mortality was severe enough to drive declining population trends.
Funding Source:
Western Newfoundland Model Forest
Newfoundland and Labrador Wildlife Division
Project Location: Western Newfoundland Model Forest
Project Duration: March 1993 - August 1995
Investigators:
Brian Sturtevant
John A. Bissonette
Technicians:
Keith Chaulk
Tina Newbury
William Dennis
The American marten (Martes americana) is associated with large tracts of
relatively undisturbed, mature coniferous forests. I examined coarse woody
debris (CWD) structure and small mammal abundance with respect to forest
age and stem structure within second-growth forests, in comparison with
old-growth stands in western Newfoundland. Results suggest that a critical
change in marten habitat quality may occur at stand senescence, due to decreased
tree competition, more complex subcanopy structure, and increased meadow
vole (Microtus pennsylvanicus) abundance.
Analysis of stem structure within a chronosequence of 19 second-growth stands
indicated high intertree competition, with dense canopy closure and active
self-thinning, until stand senescence at 80 years. Old-growth stands were
less dense, offering more canopy openings. CWD volume observed within the
chronosequence demonstrated the typical U-shaped temporal relationship observed
in other forested systems. Lowest CWD volumes were observed within semimature
to mature second growth. Highest levels of both CWD volume and structural
complexity corresponded with stand senescence and old growth.
Small mammals were sampled within immature, semimature, mature, and
silviculturally overmature coniferous stands in western Newfoundland during
1993 and 1994. Meadow voles were most abundant within overmature stands (P
less than 0.05). Vole abundance was negatively correlated with relative density
(P less than 0.01) and positively correlated with CWD (P less than 0.01).
I address the applicability of mainland marten habitat generalizations to
the unique depauperate condition of Newfoundland.
Results suggest that the critical elements of marten foraging habitat currently
are found within a senescent forest stand structure. Further review of
Newfoundland harvest records indicated that anthropogenic disturbance transformed
a historically heterogeneous forested landscape into a more contiguous,
even-aged, second-growth environment. Using the stand density management
diagram, I designed a silvicultural approach to marten habitat management
that simulates the structure of older forests within younger stages of forest
development.
Funding Source:
DOD Strategic Environmental Research Development Plan
Department of Energy
Environmental Protection Agency
Project Location: Southern California
Project Duration: January 1995-September 1996
Investigators:
Carl Steinitz, Harvard University
Craig Johnson, USU
Michael Binford, Harvard University
Ross Keister, USDA FS
Paul Cote, Harvard University
David Mouat, EPA
Thomas C. Edwards, Jr., NBS, USU
Douglas Olsen, Harvard University
Stephen Irvin, Harvard University
Allan Shearer, Harvard University
Richard T. Forman, Harvard University
Richard Toth, USU
Robin Wills, Nature Conservancy
Scott Bassett, Utah State University
This study explores how urban growth and change in the rapidly developing
area located between San Diego and Los Angeles might influence regional
biodiversity. The study region is 90 km X 120 km rectangle that encompasses
5 major river drainage basins directly influencing Camp Pendleton. The research
strategy is based on the hypothesis that the major stressors impacting
biodiversity are related to increasing urbanization. As population increases
and development spreads, habitat is lost due to grading, paving, ornamental
landscaping, and other human activities. There are also indirect effects
of development, such as changes in hydrologic and fire regimes which impact
vegetation and, ultimately, biodiversity.
A computer-based GIS was developed for the region. Analytical models use
the data in the GIS to evaluate the complex dynamic processes at work in
the study area and to provide a medium for modeling different future scenarios.
Regional change is simulated via six alternative projections of development
to the year 2010 and to subsequent "build-out." Biodiversity is assessed
in three ways: a landscape ecological model, ten selected species models,
and a species richness model. The alternative scenarios may be used by regional
stakeholders to assess the desirability of various policies affecting future
biodiversity to the area.
The project received the American Planning Associations 1996 Outstanding Achievement Award for Unique Contribution. A book contract is currently being negotiated, and various manuscripts are in progress.
Funding Source:
Utah Division of Wildlife Resources
U.S. Fish and Wildlife Service
Project Location: Great Salt Lake Wetlands
Project Duration: June 1994 - June 1996
Investigator: John A. Kadlec
Technician: Karen Lindsey
Goals and Objectives:
In the past, outbreaks of avian botulism were often observed to be associated
with re-flooding of mud-flats exposed by receding water levels in late summer.
This project will evaluate the environmental consequence of this phenomenon
in a 2-year controlled switch-back experiment using two impoundments at the
Ogden Bay Waterfowl Management Area. The first year's data, on preliminary
examination, show a large increase in sulphur as the reflooding occurs.
Presumably, this reflects an abrupt change in microbiological activity in
the sediment, which might favor enhanced growth of the botulism organism,
(Clostridium botulinum).
The second year's data confirmed an increase in soluable sulphur, most likely in the form of sulfate, at reflooding of the impoundment. In addition, pH decreases as water levels were lowered. The decreased pH most likely reflects the observed changes in sulfate concentration, mediated by the presumed changes in microbial activity. Although the micro-organisms reliant on sulphate are negatively affected by the drawdowns, the relationship between sulphur bacteria and C. botulinum is poorly understood.
Funding Source:
Utah Division of Wildlife Resources
Utah Reclamation, Conservation, and Mitigation Commission
Project Location: Strawberry Valley, Utah
Project Duration: March 1994 - January 1997
Investigators:
Curtis Knight
Rick Orme
David A. Beauchamp
Technicians:
Jane Chen
Jeffrey Godfrey
Corey Hendricks
Janene Graff
Fredrik Norrsell
Eric Asarian
Goals and Objectives:
Our objective was to estimate the potential for Bear Lake cutthroat trout
and kokanee salmon to support self-sustaining, naturally reproducing populations
in Strawberry Reservoir and its tributaries.
We estimated the timing, distribution, and abundance of spawning cutthroat
trout and resultant production of fry in tributaries to Strawberry Reservoir
in 1994 and 1995. Spawners first entered streams during the first week of
May in 1994, but the run did not accelerate until around 20 May. In 1995,
the spawning run accelerated around the first week in June. Earlier detection
of spawners was hampered by high and turbid stream flows. The beginning of
the spawning run in both years corresponded to decreasing stream discharges,
mean daily stream temperatures of around 10øC, and approximately 45
days after ice off. The majority of the spawning activity took place in Indian
Creek, Trout Creek, and Strawberry River during both years. In 1995, increased
stream flows allowed spawners to enter numerous smaller tributary streams.
An increased use of higher stream reaches was noted in 1995, likely a response
to higher stream flows. Indian Creek was the most productive stream with
an estimated 2,808 spawners in 1995 and 3,444 spawners in 1994. Spawners
in the Strawberry River were not estimated in both years due to prolonged
high flows and turbid water; however, we were able to count redds in 1994
(366). The number of spawners in Trout Creek were estimated at 605 for 1995
and 388 for 1994. Sex ratios varied between years in Indian Creek and Trout
Creek with females representing 61% of the spawners in 1994 and only 22%
in 1995. In addition, annual trend gill net data, peak spawners, sex ratios,
and estimated spawner abundance were examined for usefulness as future predictive
tools for fry production.
Indian was the most productive stream in both years, producing an estimated
561,047 fry in 1994 and 436,264 fry in 1995. Trout Creek produced 157,896
fry in 1994 and 169,632 fry in 1995. We estimated 108,536 fry produced in
the Strawberry River in 1994 and because high and turbid stream flows were
present for the majority of the spawning run in 1995, we were unable to estimate
fry production. These estimates should be considered a minimum for the whole
Strawberry Basin, as smaller streams, especially during years of high runoff
such as 1995, provided additional spawning habitat for cutthroat trout. Cutthroat
trout fry undertook two different life history strategies; fry either migrated
to the reservoir within days of emerging from the gravel or fry remained
in the stream for 1-2 years. In 1994, an estimated 21% of fry produced in
Indian Creek emigrated to the reservoir and 25% emigrated in Trout Creek.
In 1995, emigration rates were lower (3.5% for Indian Creek and 11.4% in
Trout Creek), presumably because higher stream flows provided more rearing
habitat for fry. In 1995, mean lengths and weights of fry sampled from outmigrant
fry traps were consistent (26mm and 0.10 g) throughout the fry outmigration
from 8 August to 3 September, suggesting that fry spent little time in the
stream before emigrating. Outmigrant fry traps were fished until 19 October
1995; however, very few fry migrated from 3 September to 19 October.
Population estimates of young-of-year cutthroat trout remaining in the stream
indicated that mortality rates were extremely high (99.8% in 1994, 98% in
1995) during their first growing season (August-November). Thereafter, mortality
rates were low, even during winter, and most losses from the streams were
attributed to outmigration to the reservoir. Juveniles remained in the streams
for 1-2 years with few fish remaining past three years.
Kokanee spawning and recruitment patterns were examined starting in fall 1994 through winter 1996 to determine if kokanees could become self-sustaining in the Strawberry Basin. We documented run timing and distribution of tributary spawners, and estimated spawner abundance, fecundity rates, total egg deposition, and egg-to-fry survival rates in the major spawning tributaries to Strawberry Reservoir. Spawners were more abundant and more broadly distributed in 1995 than in 1994. In 1995, we estimated that 17,838 kokanees (8,889 females and 8,949 males) spawned in Indian Creek, 10,308 (4,741 females and 5,567 males) in Trout Creek, and 2,995 (1,529 females and 1,467 males) spawned in Strawberry River. Two size modes of both sexes spawned in 1994, but only the larger mode was evident in 1995. Fecundity averaged 1,400 eggs/female and mean egg retention was 294 (SD = 419) eggs/female. We estimated that 9,859,175 kokanee eggs were deposited in Indian Creek, plus 5,366,436 eggs in Trout Creek, and 1,725,485 eggs in Strawberry River; this represented a nearly 5-fold increase over the estimated egg deposition in 1994. Our current estimates of egg-to-fry survival are 6.5% in 1994 and 8.0% in 1995. These survival rates would translate into 1,356,000 emergent fry among the three major tributaries in spring 1996, compared to 144,000 emergent fry in spring 1995. The implications of these recruitment rates for kokanee management in Strawberry Reservoir will be evaluated.
Funding Source:
Utah Division of Wildlife Resources
Central Utah Project
Project Location: Strawberry Valley, Utah
Project Duration: March 1994 - January 1996
Investigators:
James R. Ruzycki
Casey Baldwin
David A. Beauchamp
Technicians:
Jeff Godfrey
Jason Van Tassell
Vance Mumford
Goals and Objectives:
The primary management goal of Strawberry Reservoir was to provide a quality
salmonid fishery sustained by the natural reproduction of cutthroat trout
and kokanee salmon. To provide a self-sustaining fishery in a reservoir,
balance must be maintained among the various biotic and abiotic components
of the aquatic environment. To achieve a balance and to provide maximum fishery
potential, fishery stocks should be maintained near but also below carrying
capacity. Estimating the carrying capacity is therefore an important objective
of the current management plan. During 1994, we initiated a cooperative effort
with the Utah Division of Wildlife Resources (UDWR) to determine the carrying
capacity of Strawberry Reservoir. Work completed during this initial year
indicated that the reservoir's fishery was significantly below capacity.
In 1995 we refined our carrying capacity estimates and provided initial
information for examination of the food web processes which may be limiting
recruitment. These refinements include more accurate, quantified diet histories
and more representative sampling of the temporal and spatial distribution
of salmonids. The consumption demand of the salmonid community was estimated
using a bioenergetics modeling approach. Temporal and spatial distributions
of salmonids were estimated with a combination of netting and hydroacoustic
techniques.
Funding Source:
U.S. Fish and Wildlife Service
Project Location: Logan, Utah
Project Duration: October 1990 - September 1996
Investigators:
Thomas C. Edwards, Jr.
Allan Falconer
Collin Homer
Scott Bassett
Technicians:
Janene Shupe
Mary Jane Crandall
Mathew McCune
Progress to Date:
All data for the Utah component of the Great Basin Gap analysis have been
synthesized and are available in digital format for use by management agencies.
Several manuscripts have been submitted. All objectives except for the final
report have been met.
Funding source:
Utah Division of Wildlife Resources
Project Location: Flaming Gorge Reservoir, Utah-Wyoming
Project Duration: January - December 1996
Investigators:
Michael Canning
Chris Luecke
Technicians:
Phaedra Budy
Todd Seamons
Goals and Objectives:
Progress to Date:
A spatially-explicit foraging and bioenergetics model of lake trout growth
potential was developed for use in Flaming Gorge Reservoir, Utah. Abundance
of forage fish available for lake trout consumption was estimated from
hydroacoustic and trawling surveys. These surveys indicated that the abundance
of forage fish biomass declined by 40% from 1989-1995. Species dominance
shifted from Utah chub to kokanee during this period. Simulation models indicated
that the potential growth rate of lake trout should decline by 20% because
of changes in the abundance and spatial distribution
of forage fishes. Annual sampling of lake trout in Flaming Gorge Reservoir
indicated that the growth rate of marked individuals and the condition factor
of individuals captured in annual gill netting surveys declined from 1989-1995.
Information on forage fish abundance, lake trout growth, and lake trout density
was used to formulate harvest regulations for the lake trout fishery.
A combination of foraging and bioenergetics models are used to assess the
potential growth rate of other salmonid fishes given environmental conditions
of temperature, water velocity, oxygen concentration, and food availability.
Models were developed from literature values on the foraging and physiological
relationships of individual species. Model validation was conducted by growing
fish in
field enclosures. Three examples highlight the use of such models for lake
management. Simulations for kokanee in Flaming gorge Reservoir indicated
that fish assess tradeoffs between zooplankton food availability and temperature
in choosing habitats. Model simulations were used to assess stocking strategies
for salmonids. Finally, growth rate potential for lake trout was estimated
to assess the effects of forage fish reductions on the production potential
of this highly prized trophy fishery.
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