I investigated the population attributes and habitat
selection of mountain beaver (Aplodontia rufa) recolonizing
clearcuts in the Coast Range mountains of Polk and Lincoln
counties, Oregon between June 1989 and August 1990. The
population characteristics of colonizing mountain beaver
were evaluated in 12 stands of 3 types: 1-year-old
clearcuts assumed to be inhabited entirely by immigrants,
4- to 5-year-old clearcuts inhabited by immigrants and
their descendants, and 40- to 60-year-old forest stands
assumed to support stable mountain beaver populations.
Mountain beaver rapidly recolonized vacant habitat created
by previous trapping efforts; after only 1 year, densities
in clearcuts were statistically indistinguishable from
forest sites (P = 0.7). Populations in 1-year-old
clearcuts had more juveniles (P = 0.03) and had a female
bias (P = 0.02) when compared with the predominantly adult
male populations in the other two stand types. Individuals
from clearcuts were heavier than those from forest sites (P
< 0.05). Approximately half of the juvenile females in
clearcuts reproduced; no juvenile females were found to be
reproductively active in forest stands. Among juvenile
females that conceived, those in 1-year-old clearcuts had
larger litter sizes than those in 4- to 5-year-old
clearcuts (P < 0.05).
The 8 clearcuts were used to identify habitat features
selected by recolonizing mountain beaver. Clearcuts were
colonized irrespective of distances < 400 m from edge (R² =
0.01). Six habitat variables were selected by stepwise
logistic regression model colonized versus non-colonized habitat.
Mountain beaver selected areas with high amounts
(<25-cm) and large (>25-cm) woody debris, forage
plants, and uprooted stumps; they were likely to colonize
areas that had highly penetrable (soft) soils and areas
near drainages. The logistic function that included these
6 variables had a correct classification rate of 85% based
on a jackknife procedure. Forest managers may find these
habitat features useful in predicting mountain beaver
recolonization and damage. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36923 |
| Date | 12 August 1991 |
| Creators | Hacker, Amy L. |
| Contributors | Coblentz, Bruce E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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