Ten species of bats occur in the Oregon Coast Range and are hypothesized to be
associated with late-successional forests. The development of characteristics of late-successional
forests in young forest stands can be accelerated through silvicultural
practices such as thinning I examined the effects of thinning on the use of forests by bats
in the Oregon Coast Range. I used automated ultrasonic detectors to record bat calls in
50- to 100-year-old thinned and =thinned stands as well as in old-growth (2200-year-old)
stands in 11 sites in the Oregon Coast Range during the summers of 1994 and 1995. I
compared bat activity levels among the 3 stand types. In addition, I classified bat calls into
1 of 5 species groups: Eptes/Las, Myev/vo, Myyu/ca, MythCory, and Mysp. I measured
selected vegetation and environmental variables in conjunction with bat activity. I also
compared bat activity on roads with activity in the stand interior at 1 site.
Bat activity was higher in old growth than in young stands, and higher in thinned
than in =thinned stands in 1995 and over both seasons combined. I did not detect a
difference in bat activity among stand types in 1994, until I removed 1 site from the
analysis. The Mysp and MythCory species groups exhibited differences among stand
types. Bat activity along roads was higher than activity within stands.
Tree density, tree diameter, tree height, shrub cover, and shrub height varied
significantly between old-growth and young stands. Tree density, tree diameter, shrub
cover, canopy cover, and crown height varied significantly between thinned and unthinned
stands. Bat activity, overall or by species group, was significantly related to structural
variables, including mean snag diameter, mean distance from the detector to snags, and
percent shrub cover.
My results suggest that bats are sensitive to stand structure and that silvicultural
practices, such as thinning, which promote development of structural characteristics found
in old-growth stands, would benefit bat populations. Further study is needed to clarify the
habitat preferences of separate bat species and to specify habitat elements required by bat
species. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33976 |
| Date | 04 September 1996 |
| Creators | Humes, Marcia Lynn |
| Contributors | Collopy, Michael W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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