Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to...
An integrative method for monitoring glacier geometry change and mass balance is presented and applied to the Pacific Northwest, USA. Acting as a baseline for interpretation of future changes in glacier size and shape, we first derive a new inventory of regional glacier cover using remotely sensed data. To investigate...
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3.1 Study glaciers shown relative to PNW topography
Most recent research on stream amphibians in the Pacific Northwest has focused on associations with reach-level or stand-level environmental features. Little is known about landscape-level distributions of these species or landscape-level aspects of their life-histories. I used a watershed-wide sample and logistic regression to develop models and maps of probability...
Climate change is predicted to affect ecosystems, including systems already stressed by human impacts. One ecosystem that is already highly impacted by human land use is the cold headwater stream system of the Pacific Northwest. One method of assessing the function of an ecosystem is by using an indicator species....
Invasion by non-native plants into natural areas is an important component of global change that threatens biodiversity and ecosystem structure and function. Mountains are currently among the least invaded ecosystems, however, these biodiversity hotspots are increasingly under threat of exotic plant invasion. Evaluation of plant species distribution patterns in mountain...
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...
This study examined the distribution and behavior of adult spring chinook salmon
(Oncorhynchus tshawytscha) related to patterns of stream temperature and physical
habitat at channel unit, reach, and basin-wide spatial scales in both a wilderness stream
and a disturbed stream in the John Day River basin in northeastern Oregon. Thermal...
In this thesis, the spatial patterns of vegetation and soils of reference and restored tidal marshes were compared to determine the extent to which restored sites differ from the reference site after 40 years of restoration. Vegetation surveys of 1m x 1m plots were conducted along previously-established transects of salt...
The link between aboveground net primary productivity (ANPP) and resource gradients generated by complex terrain (solar radiation, nutrients, and moisture) has been established in the literature. Belowground ecosystem stocks and functions, such as soil organic carbon (SOC), dissolved organic carbon (DOC), and belowground productivity have also been related to the...
The study of the diversity of multivariate objects shares common characteristics across disciplines, including ecology and organizational management. Nevertheless, experts in these two disciplines have adopted somewhat separate diversity concepts and analysis techniques, limiting the ability of potentially sharing and cross comparing these concerns. Moreover, while complex diversity data may...