A biological inventory of the butterflies of the H. J. Andrews Experimental
Forest [HJA] in Linn/Lane County, Oregon was conducted during 1994 and 1995. It
was the first comprehensive survey of HJA butterflies for the site and serves as a
baseline for future butterfly research. A detailed ecological account is provided for
each species documented during this and previous studies from the HJA. Patterns of
butterfly richness and abundance are addressed both temporally and spatially. Within-year
and between year differences in butterfly richness and abundance are explained.
Butterfly richness and abundance were compared between forest, clear-cut, and
meadow habitats, as well as along the roads within these habitats. Butterfly richness
and abundance comparisons were also made between local butterfly hotspots and
immediately adjacent areas. Lastly, the HJA butterfly fauna was compared to those of
five other Oregon sites to put it into a regional perspective.
Seventy-two species were recorded during this two year period and increased
the total documented butterfly fauna of the HJA to seventy-nine species. Butterfly
species richness was high from June through early August. Butterfly abundance
increased gradually over the season and peaked in early August.
Each butterfly species displayed one of four patterns of combined relative
abundance and distribution: common and widespread, rare and local, common only at
low elevations or common only at high elevations. The results of standardized
butterfly counts suggested that subalpine meadows were much higher than clear-cuts
or forests in butterfly richness and abundance, and that roads served to increase
butterfly richness and abundance on a local scale in most cases. Butterfly hotspots on
the HJA appear as relatively small areas of high butterfly richness and abundance and
have a correspondingly high number of plant species when compared to adjacent
areas.
With virtually one-half of all butterfly species known for the state of Oregon,
the HJA ranks among the most species-rich locations for its size within the state. This
diversity originates from several biogeographical regions of origin, as defined within
this study. A total of 31 HJA species have a generalized Western North American
distribution, but several other biogeographical regions are also well represented.
Some butterfly species appear to be at or near their geographical limits on the HJA.
The assemblage of HJA butterfly species is virtually inclusive of those from Mary's
Peak and McDonald Forest in northwestern Oregon, whereas it differs by 30% or
more from the more biogeographically distinct faunas of Crater Lake National Park,
Mount Ashland and Steens Mountain.
Future butterfly work on the HJA is recommended. Oregon butterfly
distribution maps suggest that several additional butterfly species should be found
there. More biogeographical analyses combined with long term monitoring of HJA
butterflies could help to both predict and document changes in the Pacific Northwest
butterfly fauna due to human disturbance and global climate change. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30359 |
| Date | 31 October 2003 |
| Creators | Ross, Dana N. R. |
| Contributors | Miller, Jeffrey C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0093 seconds