Although it is generally assumed that the intensifying abiotic environment is the primary effect of drought on aquatic organisms, drought-induced top predator extinctions may be an important underlying mechanism. I used manipulative experiments to disentangle the impacts of drying and top predator extinctions on arid-land aquatic invertebrate communities. I then...
The sedimentary, metamorphic, and igneous rocks of the
Callahan, California area formed on, or adjacent to, a Lower Paleozoic
island arc complex which has since been tectonically disrupted.
Sandstone, shale, lithic wacke, chert, banded quartzite, siliceous
mudstone, conglomerate, and limestone of the eastern Klamath belt
were deposited from the Middle...
Fishery biologists and watershed management specialists have recently begun to investigate the pollutional threat posed by organic debris left in or near the forest watercourses. Oxygen content in some streams has fallen below the limits required for fish survival. The biochemical oxygen demand exerted by the debris and the reaeration...
The glaciated coastal mountain watersheds that drain into the Gulf of Alaska (GOA) provide a model laboratory to explore the challenges of hydrological modeling and study the impact of climate and glacier cover change on regional hydrology. The region is data-sparse and contains a complex assemblage of topography and land...
In many regions of the world, a significant portion of the surface water originates in mountain headwaters where the timing and magnitude of streamflow is largely dictated by the seasonal storage of precipitation as snowpack and long-term storage as glaciers. Accumulation, persistence, and melt of snow and ice are functions...
Mountain Quail (Oreortyx pictus) populations have declined in many areas of the western Great Basin during the past century. Yet the life history of this species is little known. From 1997 to 2000, I studied radio-marked Mountain Quail in Hell's Canyon in northeastern Oregon, in the Cascade Mountains of southwestern...
The topics in this dissertation center on the snow processes that dominate mountain environments in the Western U.S. and Alaska, particularly in locations lacking long-term observational datasets or locales that are difficult to access in-person. Some are currently glacierized or have been glaciated in the recent past. Each of the...
This dissertation focuses on the evolutionary forces of genetic drift and gene flow in frog populations. The balance of these two forces and the force of mutation largely determine the amount of neutral genetic variation within populations as well as the degree of genetic similarity among populations. The stochastic evolutionary...
