North America, with over 400 species of Astragalus (Fabaceae), is one of three major centers of diversity, all of which comprise the majority of the nearly 1750 species of Astragalus worldwide. One of the most diverse species, Astragalus lentiginosus of Section Diphysi, is a polymorphic complex of over 40 varieties,...
With 97% of the world’s freshwater resources stored underground, the connection between groundwater resources to the metrics of space, scale and time common to the geographic study of natural resources has not been extensively investigated by geographers. While nearly 240 transboundary aquifers are mapped across the world, a potential “tragedy”...
Pollination ecology may play an important role in the maintenance of selfing in populations of self-compatible hermaphroditic plants where both selfing and outcrossing occur (mixed mating). Behavior and abundance of pollinators can influence the two major modes of selfing; autogamy (selfing within a flower) and geitonogamy (selfing between flowers on...
Mark-recapture methods were used to examine watershed-scale survival rates of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks located in the foothills of the Cascade Mountain Range, Oregon. Differences in survival were explored among spatial (stream segment, stream network [main stem or tributaries], and watershed) and temporal...
The U.S. Forest Service on the Willamette National Forest currently employs the “Disturbed Water Erosion Prediction Project” (WEPP) model to determine potential suspended sediment delivery from timber harvests or other treatment scenarios given user-defined hillslope parameters. At the time of this study there was no known calibration or testing of...
Floods are the most frequent and damaging of all types of natural disasters and annually affect the lives of millions all over the globe. However, researchers seem to have overlooked the fact that floods do not recognize national boundaries. Therefore, the phenomena of shared, or transboundary floods occurring in international...
In 2001, an extreme drought tightened water supply in the Upper Klamath Basin (basin) while earlier increases in Endangered Species Act (ESA) water requirements for basin fish species that same year elevated demands. The Bureau of Reclamation (Reclamation), which manages irrigation water in parts of the basin located near the...
The chlamydospore is a survival spore produced by 35 of the 75 described species of Phytophthora. Phytophthora ramorum Werres, de Cock & Man in't Veld, the causal agent of Sudden Oak Death (SOD), produces abundant chlamydospores in artificial culture and plant tissue. The chlamydospore is likely the most important survival...
Silvicultural canopy gaps are emerging as an alternative management tool to accelerate development of complex forest structure in young, even-aged forests of the Pacific Northwest. I investigated patterns of nitrogen (N) availability along transects through 0.1 and 0.4 ha silvicultural gaps in three 50-70 year old Douglas-fir forests of western...
I studied small-mammal communities and their response to grazing in mixed-conifer forests and oak woodlands in the Cascade-Siskiyou National Monument in southern Oregon. My objectives were to (1) compare small-mammal communities among forest types and grazing intensities, (2) identify riparian affiliated species, and (3) describe microhabitat associations. Over two years,...