## Progress Report 08 May 2001

## Project Title: Assessing wildland fire impacts on the winter habitat use and distribution of caribou within Alaska's boreal forest ecosystem

## Period: 1 July 1999 - 31 March 2001

## Investigators:

## Bruce Dale, Alaska Department of Fish and Game, Palmer, Alaska

##  William Collins, Alaska Department of Fish and Game, Palmer, Alaska

##  Kyle Joly, USGS-Alaska Biological Science Center, Anchorage, Alaska

##  Layne Adams, USGS-Alaska Biological Science Center, Anchorage, Alaska

## Collaborators: University of Alaska fairbanks: Scott Rupp; University of Vermont: Darien McElwain; Alaska Department of Fish and Game: Earl Becker, Craig Gardner, Brad Scotton, Tom Stephenson, Bob Tobey, Patrick Valkenburg.

## 

# summary

In July 1999, the Alaska Department of Fish and Game-Division of
Wildlife Conservation (ADF&G) and the US Geological Survey-Alaska
Biological Science Center (USGS) began a 5-year investigation of the
impact of boreal forest fires on the Nelchina Caribou Herd (NCH) in
south-central and interior Alaska. Wildland fire kills the late
succession fruticose lichens used as winter forage by caribou and it may
be decades before such lichens are again abundant. In the late 1980s the
NCH shifted it's primary winter range use from the historic wintering
ground in the Copper and Nelchina River basins to an area of
comparatively much higher fire frequency over 150 miles to the
northeast. Approximately 85% of the herd now migrates across the Alaska
Range to winter in this northern study area (NSA). This collaborative
research effort evaluates relationships between fire history and lichen
abundance; caribou habitat selection relative to lichen abundance; and
caribou nutritional performance and survival relative to habitat
selection, lichen abundance, and spatial distribution. Results of this
study will provide information directly applicable to caribou and fire
management in Alaska. During this reporting period, ADF&G and USGS
cooperators generated a comprehensive proposal and secured review by
several agency and university scientists.

In addition, we captured, weighed and measured body size parameters of
\>80 caribou in early October 1999 and 2000. We deployed 35-40
conventional radio-collars on each cohort of 4-month-old female calves
and maintained a sample of \>20 GPS radio-collars on adult females. We
estimated survival rates and habitat use patterns by obtaining \>1200
relocations of radio-collared animals by aerial radio-telemetry and
\>20,000 relocations from GPS telemetry each year. We evaluated the
seasonal nutritional performance of individual caribou by recapturing
and handling surviving caribou in April and again the following October.
Blood samples were collected at each handling for evaluating the use of
stable isotopes as indicators of dietary lichen and nutritional status
in collaboration with T. Stephenson (ADF&G, Kenai Moose Research
Station). Weight change of calves was variable as calves gained weight
over the winter of 1999-2000, but lost weight during the winter of
2000-2001. Caribou strongly avoided boreal forest stands within the NSA
that had burned since 1966.

We evaluated caribou habitat selection relative to post-fire stand-age
by comparing locations caribou used to random sites. We estimated stand
age, forage lichen cover, lichen biomass, cover of other vegetation, and
other habitat parameters within the NSA by on-site point sampling at a
random subset of 120 of the conventional caribou locations and at 100
random locations. Caribou forage lichens were scarce on stands that had
burned within the last 60 years for both random and used sites
indicating a lengthy recovery period for burned winter range. Caribou
strongly selected for older stands that had abundant primary and
secondary caribou forage lichens.

Cover (%) of forage lichens correlated strongly with biomass suggesting
that remote sensing of percent cover can be used to estimate winter
forage availability. Because on-site sampling is expensive and
time-consuming, we developed a technique for estimating forage lichen
abundance using aerial digital videography. While we had proposed to
evaluate various aircraft and imaging formats, our initial results
employing cost effective digital videography from fixed-wing aircraft
proved satisfactory. We established fixed plots on 5 stands representing
a broad range of forage lichen abundance. We adjusted camera settings
and flight parameters until we acquired images that provided for the
detection of forage lichen cover as low as 10-15%. Digital images of
1000m x 40m transects were then acquired at all the used and random
on-site sampling locations. We will estimate lichen cover from the
images and compare them (via regression) to the on-site measurements of
cover and biomass. Subsequently, we will use aerial videography to
generate lichen abundance estimates.

We established experimental plots to evaluate the influence of fire on
lichen regeneration and growth on the historic winter range. Lichen
fragments were "seeded" on burned and unburned, spruce-shaded and
unshaded treatments of moss and duff (or mor) substrates. In addition,
lichens were marked to verify the presence of annual nodal branching for
use as markers to measure annual growth of individual thalli. These
experiments will be re-evaluated during the summer of 2001.

A pilot study was initiated to evaluate the feasibility of using tame
caribou to conduct on-site field trials of forage selection, foraging
efficiency, and nutritional performance within stands of various ages in
the NSA and within the historic winter range. Four 1-day old female
Nelchina caribou calves were captured and hand-raised in Palmer and at
the Kenai Moose Research Station. On March 1^st^ 2001, these animals
were transported to temporary pens on the historic winter range. We
collected blood and urine samples and weighed the animals immediately
prior to and after each trial. After a period of adjustment to range
conditions, activities of individual caribou were recorded every 15
minutes over two 24-hour periods and diets were scan sampled. At the end
of two weeks, we transported the caribou to the comparatively
lichen-rich areas of the NSA. Following that 2-week trail, we conducted
an additional 1-week replicate trial on each range. Caribou lost weight,
foraged less selectively, and ruminated longer on the historic winter
range. Caribou were more selective and gained weight on the NAS.
Subsequently, we plan to conduct field trails over a range of lichen
availabilities and snow conditions to further evaluate caribou foraging
efficiency, diet selection, and nutritional performance for different
stand ages and lichen availabilities.

We established a cooperative effort with Scott Rupp and the University
of Alaska to model the influence of fire frequency, as influenced by
fire management or climate change, on expected availability of caribou
winter range. An existing frame-based model, ALFRESCO, will be employed
to estimate the total area, spatial distribution, and age distribution
of black spruce stands within the NSA under various fire regimes. We
will combine the output of that model with the lichen abundance -- stand
age relationships and caribou habitat selection for stand-age to
estimate the total forage lichen biomass and total area of selected
winter habitats to rank winter range under various fire regimes.

## Key Words: Caribou, wildland fire, lichen, habitat selection, nutritional performance, survival, boreal forest succession, 

# Contents

**SUMMARY**...................................................................................
1

**[BACKGROUND]{.smallcaps}**.............................................................................
3

## METHODS.................................................................................\... 5

**RESULTS**.....................................................................................
10

**DISCUSSION**..............................................................................\...
12

**LITERATURE
CITED**..................................................................\...
13

**FIGURES**.....................................................................................
14

# Background

Caribou wintering in boreal forest ecosystems of Alaska forage primarily
on "climax" stage fruticose lichens. Wildland fires, however,
chronically burn boreal forests, reducing the availability of forage
lichens for decades. In addition, prescribed fires have been implemented
to reduce fire hazards, restore biodiversity or enhance moose habitat.

Since the early 1900s, wildland fire has been implicated in caribou
population declines. Numerous studies reveal reduced lichen
availability, long lichen recovery periods, and caribou avoidance of
recently burned winter ranges. However, direct evidence for fire induced
population declines is notably lacking. Moreover, researchers have long
debated the importance of lichens to caribou. Although lichens dominate
winter diets when available, examples of robust caribou populations
utilizing lichen-poor ranges suggest that high-quality summer range or
alternate winter forages can supplant lichen-rich winter range.

In addition, numerous investigators suggest that fire may rejuvenate
older lichen ranges by favorably altering moss-lichen relationships,
reducing overstory, or removing decadent lichens. Fire may also alter
caribou movement patterns, thereby allowing recovery of over-grazed
lichen ranges. Lastly, fire likely enhances summer range through
nutrient turnover and increased quality and abundance of vascular
forages. Contrary to assertions that fire is detrimental to caribou,
these mechanisms suggest that wildland fire may play a role in
maintaining caribou winter range or enhancing nutritional status.

The NCH provides ideal opportunities to investigate many aspects of the
influences of boreal forest fires on caribou. The NCH ranges over a
large portion of south central Alaska that is influenced by a variety of
prescribed and wildland fire management regimes. During the last 2
decades, the herd shifted its primary winter range from an area of very
low fire frequency to a highly fire-influenced system north of the
Alaska Range (Figure 1). This NSA winter range has limited vegetative
diversity other than that generated by wildland fire occurrence. In
addition, 2 prescribed fires to enhance moose habitat have recently been
conducted on this winter range and another is scheduled for a portion of
the summer range. These characteristics, along with a substantial
history of research, provide unique research opportunities.

Management of the NCH generates substantial public interest because of
its accessibility to a large portion of the Alaskan public for both
subsistence and general uses. Understanding caribou/fire relationships
on ranges of the NCH will provide information for herd management
locally, and fire management throughout the boreal forest ecosystem of
Alaska and Yukon.

1\. Determine the relationships between fire history and forage lichen
abundance and condition.

> H1. Forage lichen abundance and productivity increases with stand age
> to roughly 50-100 years, then declines.
>
> H2. Fire promotes lichen growth by reducing overstory or moss and
> increasing soil temperatures in declining and grazing-depleted lichen
> stands.

2\. Investigate the importance of lichen, and therefore fire history, in
determining caribou habitat selection.

H3. Historic winter ranges in the Nelchina Basin have lower lichen
abundance than currently used winter ranges north of the Alaska Range.

> H4. Caribou avoid burned areas for decades post-fire and select for
> older stands with abundant forage lichens.
>
> H5. Winter movement patterns are influenced by lichen abundance.

3\. Evaluate relationships between habitat selection of caribou and
their nutritional performance.

> H6. Caribou utilizing lichen-rich winter ranges gain more or lose less
> weight than caribou utilizing lichen-poor ranges.
>
> H7. Caribou weight gain on preferred winter ranges is independent of
> caribou density on those ranges.
>
> H8. Weight change is related to the proportion of lichen in the winter
> diet of caribou calves.
>
> H9. Winter weight change is independent of summer weight gain.

4\. Evaluate survival and nutritional tradeoffs associated with various
spatial distributions on seasonal ranges of caribou.

> H10. Nutritional performance is negatively correlated with local
> density of caribou but survival rates are positively correlated with
> local density.

The raw data, results, and conclusions presented within this report are
quite preliminary and should not be cited.

# Methods

## Fire and abundance of forage lichens

### Lichen abundance vs. stand age. We investigated the relationship between abundance of forage lichens and post-fire stand-age within the NSA by on-site sampling at a subset of winter caribou locations and at a similar number of random sites. Age of each stand was determined from sections of spruce trees and Alaska Fire Service (AFS) maps and databases. Lichen cover, as well as cover by other vegetation, was estimated at 0.5m point intercepts along a 60 m transect randomly oriented at each site. Our objective was to estimate lichen cover by species as well as cover of any overlying canopy that could prevent detection of forage lichens from aerial imagery. Therefore, we recorded cover at each point with a single hit in each of the following strata: ground species (lichens, mosses, Vaccinium vitis-idaea, Empetrum nigrum, etc.); low species (Carex spp., Eriophorum vaginatum, Vaccinium uliginosum, etc.), shrubs (Betula nana, B. glandulosa, Salix spp., Alnus spp.), and by trees (Picea mariana, P. glauca, Populus tremuloides, Betula papyrifera). Overtopping cover data will be used to generate correction factors for estimation of lichen coverage by aerial imagery.

Depth of forage lichen mats and biomass were determined in all sites by
collecting and later measuring and weighing 12 cm diameter plugs of
forage lichens taken at 6 randomly selected points along each transect.
Length and age of living and dead thalli from the *Cladina* spp*.*
lichens were measured and related to the ages of stands.

*Development of digital imagery techniques.* We evaluated aerial
videography to determine which image size (altitude and camera focal
length) and airspeeds best allowed estimation of forage lichen coverage.
To develop the technique, established nested plots at 5 sites that
represented a broad range of lichen abundance. Nine adjacent 10x10m
quadrats provided a nested series of 10x10, 20x20, and 30x30m plots for
efficient evaluation of aerial images at different scales.

The corners of the center quadrat of each cluster were marked with
surveyor's section flagging so as to be distinguished from the air.
Lichen cover within quadrats was estimated from 25 systematically spaced
2m line intercepts, with coverage being classified as either open to the
sky or covered by taller vegetation. The center 10x10m quadrat, 20x20m
and 30x30m nested clusters were then imaged with a Sony PD-150 digital
video camera from 200-1000 feet above ground level from a DHC-2
fixed-wing aircraft. Altitudes above ground level were determined by
radar altimeter. Images were geo-referenced by synchronizing video clock
times with real-time aircraft GPS locations and time recorded from a
Garmin 100 GPS using a laptop computer and PHOTOMAN software (R. Delong,
ADF&G Fairbanks).

### Images from sampling locations were captured into JPEG computer images using Sony Dvcap software. These images were then imported into ARCView GIS and enhanced as necessary with the Image Analyst ARCView extension (ESRI). Total coverage of forage lichens from imagery was estimated by the noting the presence or absence of caribou forage lichens at each intersection of a 50-point grid superimposed over the digital image. Total coverage and variability of estimates from imagery will be compared with those of on-site samples to further verify the validity of the technique. 

*Fire history mapping*: Substantial fire history information was already
available from AFS as digital map products and databases. We began fine
tuning the existing GIS coverage by searching AFS files for additional
fires and adding them to digital coverages. An effort to map all fires
greater than 0.405 km^2^ (100 acres) was made. However, information
about numerous fires has been lost over the years and fires under 4.05
km^2^ (1,000 acres) in size were often not recorded. Almost no
information is available for fires dating before 1950.

*Factors influencing lichen recovery and regeneration*. Possible effects
of organic substrates and nature of disturbance on early lichen recovery
will be examined on lichen fragments which we "seeded" into burned and
unburned sphagnum moss; burned and unburned duff or mor; and
spruce-shaded and unshaded duff or mor. All plots were selected for
uniformity in vegetation type, micro-topography, and exposure. Burned
plots were prepared under uniform conditions and exposure to a weed
burner. Portions of unburned plots were cleared of existing lichens to
make room for placement of fragments. Existing mats of *Cladina* spp.
were left undisturbed in a portion of each plot to provide a reference
to growth rates of established lichen. Fragments of *C. rangiferina*,
*C. mitis, C. amaurocraea, Cetraria laevigata, and C. cucullata* were
prepared by cutting 1cm lengths of photosynthetically active tips and
1cm lengths of 5- to 10-year-old thallus. Fragments were spaced at 5 cm
intervals in 1 m lines and protected by cages constructed of concrete
reinforcement mesh. Fragments will be measured with calipers about the
end of June annually. Vegetation cover in the protected plots and in
adjacent unprotected, paired plots will be determined from digital
imagery or by point grid sampling when lichens are measured for
growth*[.]{.smallcaps}*

## Lichen abundance and caribou habitat selection

We employed GPS telemetry and conventional telemetry to gather
information on seasonal distribution and movements of caribou. That
data, in concert with GIS coverages described above and additional
sampling of forage lichen abundance utilizing fine-scale aerial imagery,
allowed us to evaluate habitat selection by caribou on a variety of
spatial scales.

*Capture and Handling*. Caribou were captured via standard helicopter
chemical immobilization techniques. Caribou were weighed via electronic
load cell and skeletal measurements were taken. Blood samples were
collected for disease screening, analysis of stable isotopes and
pregnancy determination. Each individual was fitted with a conventional
or GPS radiocollar.

*GPS telemetry*. We employed GPS telemetry for estimating habitat
selection at temporal scales that were not possible with conventional
telemetry and evaluating the influences of relocation frequency on our
estimates of caribou distribution and habitat selection. Beginning in
October 1999, we maintained a sample of 20 female caribou fitted with
GPS radiocollars that also had conventional mortality-sensing telemetry
beacons. Onboard GPS receivers were programmed to collect locations
every 7 hours and store those locations to memory included in the
collar. In April, GPS-instrumented caribou were recaptured to download
stored location data and to replace batteries.

*Conventional telemetry.* In addition to the GPS instrumented
individuals, we maintained a sample of about 100 caribou with
conventional radiocollars. Therefore, our sample of caribou instrumented
for conventional telemetry was about 120 animals. In addition,
approximately 80 instrumented caribou from the Mentasta herd, which
shares winter range with the Nelchina herd, were also monitored. We
attempted to locate all instrumented caribou monthly by aerial
radiotelemetry. Observers recorded location, as determined by
aircraft-born GPS units, and group size for all observations of
instrumented caribou. During winter months, evidence of cratering was
also recorded. Mortalities were noted during radiotracking flights and
mortalities were investigated via helicopter as soon as practical.

## Habitat selection

*Selectivity for post-fire age of stand*. Although a complete
understanding of fire history over the 68,000 sq. km range of the NCH is
unattainable, we have substantial information on fire history,
particularly in the winter ranges currently being used north of the
Alaska Range. We believe the resulting GIS coverage of fire history,
although incomplete, will be adequate for evaluating selectivity
relative to stand-age.

Both GPS and conventional telemetry data, in separate analyses, will be
used to estimate use among known-age stands. To estimate the
availability of various post-fire age classes, we will delineate the
extent of winter range north of the Alaska Range as the area enclosed by
the minimum convex polygon of all locations during November-March.
Selectivity relative to post-fire stand age will be estimated annually
and evaluated relative to factors that may induce variability among
years (e.g. snow conditions or other weather characteristics). If
appropriate, analyses will be pooled over all years. Lichen
abundance-stand age relationships will be estimated via aerial imagery
to compare selectivity related to stand age with patterns of lichen
abundance. Ultimately, a logistic regression model will be constructed
to evaluate influences of lichen abundance, stand age, land cover,
landform, and environmental parameters on selectivity.

*Movement patterns and lichen abundance*. To evaluate selection for
lichen abundance at a finer scale, we will explore relationships between
observed caribou movement patterns and lichen abundance. We hypothesize
that lichen is more abundant in areas where caribou localize. Utilizing
data from the movements of GPS-instrumented caribou during winter, we
categorized locations by movement pattern as reflected in relative
densities of sequential point locations. Locations of individual animals
were mapped and fixed-width kernel density estimates were calculated at
each location. The width of the smoothing factor was adjusted so that a
frequency plot of the density estimates revealed about 3 modes that
described the mid- points of the movement categories. Missing point
locations were estimated by interpolation from the next successful
attempt. Although this introduced error into the analysis, bias in
habitat or topographic related failure of GPS satellite acquisition was
reduced.

Following categorization, we randomly selected 50 locations from each
movement category. Lichen abundance will be determined at each of these
locations via aerial imagery. We will use ANOVA to evaluate whether
arc-sine transformed lichen cover estimates vary among movement
categories. In addition, we will use these data to test the hypothesis
that lichen cover at a caribou location influences the distance and
change in bearing traveled to the caribou's subsequent location. For
this analysis we will employ multiple regression techniques thereby
facilitating the incorporation of other variables, such as temperature,
snow pack depth, and time-of-day, into the model. Indicator variables
will be transformed as appropriate for least-squares regression and
evaluated via stepwise selection. The response variable will be a vector
consisting of the distance traveled divided by the relative change in
heading (0-180 degrees) from the previous movement.

## Nutritional performance and survival of caribou

As part of our conventional telemetry sample, we captured and
radio-collared approximately 40 5-month-old female calves using standard
methods described above. These animals were weighed, measured, and
blood-sampled. They were recaptured in mid-April at 11-months-old and
processed similarly. Weight change of these calves, expressed as weight
gain/loss or percent change over winter and arc-sine transformed for
parametric statistical analyses, were the basis of our evaluations of
habitat effects on nutritional performance. Weight change data will
first be evaluated to detect variation among cohorts (ANOVA) or
relationships between fall body weight (i.e. summer weight gain) and
subsequent winter weight change (least-squares regression).

At the broadest scale, we compared nutritional performance of caribou
calves that wintered in the Nelchina Basin, on lichen-depleted ranges,
with those that wintered north of the Alaska Range where forage lichens
are expected to be more abundant (ANOVA). At the next level, caribou
calves will be grouped based on their within-season spatial distribution
through hierarchical cluster analysis with average linking. Variation in
weight change among clusters will be evaluated by ANOVA with arc-sine
transformation of the dependent variable. In these analyses, scale can
be adjusted by varying the number of clusters. If regional variation in
nutritional performance is detected, then that variation will be
evaluated relative to lichen abundance based on models developed from
satellite imagery and/or fine-scale aerial imagery collected for
selectivity analyses. At the finest scale, we hope to be able to
categorize the importance of lichen in the winter diets of individual
calves, based on stable isotope analyses of blood samples, and compare
that to their weight change. Environmental variables were derived from
weather data collected by NOAA and FAA weather stations in Tok,
Northway, Paxson, Glennallen, Eureka, Palmer, Talkeetna, and Cantwell
and remote fire weather stations throughout the area.

A pilot study was initiated to evaluate the feasibility of using tame
caribou to conduct on-site field trials of forage selection, foraging
efficiency, and nutritional performance within stands of various ages in
the NSA and within the historic winter range. Four 1-day old female
Nelchina caribou calves were captured and hand-raised in Palmer and at
the Kenai Moose Research Station. On March 1^st^ 2001, these animals
were transported to temporary pens on the historic winter range. We
collected blood and urine samples and weighed the animals immediately
prior to and after each trial. After a period of adjustment to range
conditions, activities of individual caribou were recorded every 15
minutes over two 24-hour periods and diets were scan sampled. At the end
of two weeks, we transported the caribou to the comparatively
lichen-rich areas of the NSA. Following that 2-week trail, we conducted
an additional 1-week replicate trial on each range. Caribou lost weight,
foraged less selectively, and ruminated longer on the historic winter
range. Caribou were more selective and gained weight on the NAS.
Subsequently, we plan to conduct similar field trails over a range of
lichen availabilities and snow conditions to further evaluate caribou
foraging efficiency, diet selection, and nutritional performance for
different lichen availabilities. These field trials would help determine
the lichen biomass and distribution necessary for weight maintenance or
gain thus allowing evaluation the relationship between age of stand and
winter range habitat capability.

## Evaluation of Fire regimes on caribou winter range availability

Appropriate models will be developed to evaluate the influence of fire
management regimes on lichen abundance, suitability of boreal forest as
caribou winter range, caribou movements and distribution, nutrition and
survival trade-offs, seasonal range trade-offs, and caribou population
dynamics. These models will incorporate data from this and other
research where appropriate. The specific types of models constructed
will necessarily reflect the nature and significance of relationships
identified in this research effort (Starfield and Bleloch 1991).

A spatially explicit time-series model of the influence of various fire
management regimes on lichen abundance will be particularly useful for
managers. Fire recurrence will be varied over seasonal ranges of the NCH
to simulate the effects of various fire suppression regimes. Fires will
vary stochastically in size and shape within the parameters of previous
fires within that locale thereby creating a complete mosaic of stand-age
polygons. Lichen abundance within stands will reflect the age of the
stand and the area of boreal forest within the stand as determined from
AVHRR or other vegetation classification maps. Lichen removal from
grazing will be simulated using rates estimated by Arseneault (*et al*.
1997) adjusted for herd size and distributed among stands following
stand-age selection models developed from this study. Range-wide
abundance of forage lichens in boreal forests within the range of the
herd will be calculated for varying fire recurrence intervals. Caribou
nutritional status and population dynamics may be incorporated into the
model where appropriate.

This model will provide managers a tool to evaluate the abundance of
caribou forage lichens expected under various fire regimes. In addition,
because of the spatially explicit structure, it allows evaluation of
variation in fire recurrence among specific portions of the NCH range.
Because it is a time-series model, it allows evaluation of shorter-term
temporal effects of changes in fire recurrence.

# results

Progress to date entails primarily data collection. Some very limited
and preliminary data analyses have been conducted and a few subjective
observations were made.

*Development of digital imagery techniques.* We set up the nested plots
in 5 stands along the Taylor highway. We tried various altitudes and
camera settings to obtain clear images of the ground vegetation and
suitable color. Altitudes of 250-400' above ground level and airspeeds
of 60-80 knots, an approximately 3x zoom setting and a shutter speed of
1/1000 of a second provided excellent resolution and color over a
roughly 30x40m area (Figure 2). By the end of this reporting period, we
obtained aerial images for 86 caribou locations and 48 random points.

*Lichen abundance vs. stand age*. By the end of this reporting period,
we estimated lichen abundance at over 100 caribou locations and 100
random points (Figure 3). Caribou forage lichens were virtually absent
from stands under 60 years of age, post-fire (Figure 4). Percent cover
of primary and secondary forage lichens increased with stand age after
about 85 years, post- fire. Percent lichen cover was strongly correlated
with biomass (Figure 5). We collected data on numerous co-variates, such
as topography, to further explain variation in lichen abundance but
those analyses have not been completed.

*Fire history mapping*: We gathered fire history data and compiled a GIS
layer covering the entire study area. We believe the available
information represented most fires since 1950 that burned more than 1000
hectares. However, no fires were reported for the current winter range
north of the Alaska Highway until 1966. Given the fire frequency in the
area, it is likely that significant fires from 1950 -- 1965 are not yet
recorded. We will attempt to delineate these and older fires during
ground-truthing efforts.

*Capture and Handling*. We captured 83 caribou in autumn 1999 and
deployed GPS or conventional transmitters, or collected body
measurements and blood samples. In late April of 2000 we re-captured the
surviving radio-collared animals, replaced collars or batteries as
required, and again estimated nutritional condition. Again in October of
2000, 87 caribou were captured. We investigated mortalities and
retrieved collars as necessary.

*Selectivity for post-fire age of stand*. We collected 1242 conventional
aerial telemetry relocations for approximately 207 Nelchina and Mentasta
caribou for estimating winter habitat use. These locations included
estimates of group size and presence or absence of feeding craters. We
plotted these data relative to the burn history GIS layer for the
current winter range north of the Alaska Highway (Figure 6). Of 585
locations on the winter range north of the Alaska Highway, 2.1% occurred
in areas burned since 1966. These burns represented 16.7% of the study
area. The same pattern was evident in during the winter of 2000-2001
(Figure 7).

*Movement patterns and lichen abundance*. Approximately 10,000 GPS
relocations were obtained for 20 animals fitted with GPS collars. We
have just begun point density estimates for stratifying these locations
into movement patterns. Of the 6687 winter locations north of the Alaska
Highway, 3.9% occurred in areas burned since 1966 (Figure 8). Lichen
biomass was significantly higher at locations used by caribou than at
random locations within the NSA (Figure 9). Sites older than 80 years
were used disproportionately by caribou while sites younger than 80
years were avoided (Figure 10).

*Nutritional performance and survival of caribou*. We obtained measures
of over-winter changes nutritional status (body size and weight) on 17
cows and 35 calves that survived the winter of 1999-2000. We plan to
recapture survivors from the 2000 cohort in October 2001. Comparable
data was collected for the 1998 and 1999 calf cohorts (Table 1). In
addition, we collected data for estimating over-winter survival rates
for approximately 120 Nelchina caribou (Table 2).

The pilot study to evaluate foraging efficiency and nutritional
performance through field trails of tractable animals proved to be
feasible. Although numerous obstacles were encountered, the animals
proved tractable. Preliminary analyses indicate that the animals were
less selective, increased foraging effort, and lost weight when grazed
on the historic winter range. When grazed on the NSA, caribou were more
selective and maintained or gained weight. We are currently evaluating a
study design for an additional series of field trials on ranges with
intermediate lichen abundance.

*Factors influencing lichen recovery and regeneration.* We established
experimental plots to evaluate the influence of fire on lichen
regeneration and growth on the historic winter range. Lichen fragments
were "seeded" on burned and unburned, spruce-shaded and unshaded
treatments of moss and duff (or mor) substrates. In addition, lichens
were marked to verify the presence of annual nodal branching for use as
markers to measure annual growth of individual thalli. These experiments
will be re-evaluated during the summer of 2001.

Table 1. Age-specific mean (n, sd) weights of radio-collared individual
caribou from the 1998 and 1999 cohorts.

  ----------- ------------------ ------------------- ---------------------
  Cohort      4 months           10 months           16 months

  1998        51.0 (7, 3.8)      51.5 (7, 4.6)       75.8 (22, 11.9)

  1999        51.7 (35, 4.7)     48.7 (23, 3.9)      74.8 (21, 8.4)

  2000        53.5 (37, 6.6)     N/A                 N/A
  ----------- ------------------ ------------------- ---------------------

Table 2. October 1999 -- March 2000 and October 2000 -- March 2001
survival data.

+------------+----------------+-------------------+-------------------+
| Age Class  | Number at risk | Number surviving  | Percent surviving |
|            |                |                   |                   |
|            | 99-00 00-01    | 99-00 00-01       | 99-00 00-01       |
+------------+----------------+-------------------+-------------------+
| Adults     | 65 76          | 59 72             | 90.8% 94.7%       |
+------------+----------------+-------------------+-------------------+
| Yearlings  | 21 13          | 10 11             | 47.6% 84.6%       |
+------------+----------------+-------------------+-------------------+
| Calves     | 34 34          | 22 19             | 64.7% 55.9%       |
+------------+----------------+-------------------+-------------------+

*Evaluation of fire regimes on caribou winter range availability:* We
established a cooperative effort with Scott Rupp and the University of
Alaska to model the influence of fire frequency, as influenced by fire
management or climate change, on expected availability of caribou winter
range. An existing frame-based model, ALFRESCO (Rupp et. al. 2000), will
be employed to estimate the total area, spatial distribution, and age
distribution of black spruce stands within the NSA under various fire
regimes. We will combine the output of that model with the lichen
abundance -- stand age relationships and caribou habitat selection for
stand-age to estimate the total forage lichen biomass and total area of
selected winter habitats to rank winter range under various fire
regimes.

# discussion

The expansion of this study to a collaborative effort between USGS and
ADF&G facilitated the investigation of numerous aspects of caribou
ecology. In addition, the collaboration has resulted in the assembly of
an experienced research team with varied but complimentary expertise.

Data collection and analyses are just beginning. Aerial videography
shows considerable promise for remote estimation of lichen cover.
Caribou appear to be selecting strongly for lichen abundance, which in
turn appears related to stand age. Caribou showed little use of areas
known to have burned since 1966. Caribou use areas were predominately
older than 60 years since fire.

# acknowledgments

We would like to thank and acknowledge the support and/or services
provided by H. McMahon, R. Swisher, T. Cambier, and S. Gibbens (aircraft
support); R. Staudenmeier, L. Zaczkowski, A. Keech, T. Taube, N.
Deslauriers, J. Tuttle, and many other ADF&G staff (administration and
logistics); G. Roffler and D. Spalinger (vegetation analyses); L.
Vanderlinden, D. Derksen, and D. Spalinger (project coordination and
oversight); D. Spalinger, D. Derksen, R. Farnell, R. Hayes, B.
Griffiths, T. Hanley, R. Jandt, L. Saperstein, T. Paragi, W. Testa, J.
Woolington, R. Sellers, T. Stephenson, W. Taylor, M. Keech, M.
Masteller, and H. Griese (study plan review).

# Literature cited

Arseneault, D. N., Villeneuve, C. Boismenu, Y. Leblanc and J. Deshaye.
1997. Estimating lichen biomass and caribou grazing on the wintering
grounds of northern Quebec: an application of fire history and Landsat
data. 34(1):65-78.

Rupp TS, Starfield AM, Chapin III FS (in press) A frame-based spatially
explicit model of subarctic vegetation response to climatic change:
comparison with a point model. *Landscape Ecology*

Starfield, A.M. and A.L. Bleloch. 1991. Building models for conservation
and wildlife management. 2^nd^ edition. Macmillan/Burgess, MN. 253pp.

List of Figures

Figure 1. Winter range locations in Jan - Mar 1980-1985 (n=301, from
Pitcher *et al*. unpublished data) and Jan -- Mar 1999-2000 (n=271, this
study).

Figure 2. Aerial image depicting caribou forage lichens in a black
spruce stand. Image was taken with a digital video camera from a fixed
wing aircraft at an altitude of 300 feet.

Figure 3. Used and random ground sampling locations for the current
winter range north of the Alaska Highway.

Figure 4. Percent cover of primary caribou forage lichens plotted
against age of stand.

Figure 5. Relationship between percent cover and biomass of caribou
forage lichens.

Figure 6. Conventional telemetry locations within the northern study
area Oct - Apr, 1999-2000 relative to fire history since 1966 (n=585).

Figure 7. Conventional telemetry locations within the northern study
area during December 2000 through March 2001 (triangles) and December
1999 through March 2000 (circles).

Figure 8. GPS telemetry locations and fire history since 1966 within the
northern study area Oct -- Apr, 1999 -- 2000.

Figure 9. Lichen biomass at locations used by caribou and random
locations within the northern study area.

Figure 10. Age of vegetation plots; caribou locations versus random
points.

![](media/image1.png){width="8.660416666666666in"
height="6.493055555555555in"}

Figure 1. Winter range locations in Jan - Mar 1980-1985 (n=301, from
Pitcher *et al*. unpublished data) and Jan -- Mar 1999-2000 (n=271, this
study).

![](media/image2.wmf){width="8.660416666666666in"
height="6.493055555555555in"}

Figure 2. Aerial image depicting caribou forage lichens in a black
spruce stand. Image was taken with a digital video camera from a fixed
wing aircraft at an altitude of 300 feet.

![](media/image3.png){width="8.489583333333334in"
height="6.395833333333333in"}

Figure 3. Used and random ground sampling locations for the current
winter range north of the Alaska
Highway.![](media/image4.png){width="7.1in"
height="6.499305555555556in"}

Figure 4. Percent cover of primary caribou forage lichens plotted
against age of stand.

![](media/image5.png){width="7.041666666666667in" height="4.4375in"}

Figure 5. Relationship between percent cover and biomass of caribou
forage lichens.

![](media/image6.png){width="8.995138888888889in"
height="6.4847222222222225in"}

Figure 6. Conventional telemetry locations within the northern study
area Oct - Apr, 1999-2000 relative to fire history since 1966 (n=585).

![](media/image7.png){width="7.822916666666667in" height="6.375in"}

Figure 7. Conventional telemetry locations within the northern study
area during December 2000 through March 2001 (triangles) and December
1999 through March 2000 (circles).

![](media/image8.png){width="8.875in" height="6.40625in"}

Figure 8. GPS telemetry locations and fire history since 1966 within the
northern study area Oct -- Apr, 1999 -- 2000.

![](media/image9.png){width="8.260416666666666in"
height="5.395833333333333in"}

Figure 9. Lichen biomass at locations used by caribou and random
locations within the northern study area.

![](media/image10.png){width="7.5625in" height="4.791666666666667in"}

Figure 10. Age of vegetation plots; caribou locations versus random
points.