To begin to understand freshwater seasonal floodplain fish communities in the context of human alteration of the physical system, species introductions and wetland restoration efforts, I studied fish assemblages in fifteen seasonal floodplain wetlands within four geographic regions (coastal, upper Columbia River estuary, Puget Sound and eastern Oregon/Washington) in the...
This thesis provides the first general description of the natural variation in age
structure, growth rates, and survival in headwater populations of coastal cutthroat
trout Oncorhynchus clarkii clarkii from western Oregon, and a subsequent
synthesis of these life-history characteristics across the range of the subspecies.
Age, growth, and survival were...
Spatially explicit maps of habitat relationships have proven to be valuable tools for conservation and management applications including evaluating how and which species may be impacted by large scale climate change, ongoing fragmentation of habitat, and local land-use practices. Studies have turned to remote sensing datasets as a way to...
The western United States has experienced large-scale degradation due to land use and land cover changes, invasion of annual grasses, and expansion of woody plants into grass and shrublands and the resultant altered fire regimes. These landscape-scale changes have coincided with declining mule deer (Odocoileus hemionus) populations, making habitat loss...
Most wild animals are concurrently infected with multiple parasite species for most of their lives. These parasite species assemble into rich and diverse communities, with parasites using host tissues for growth and reproduction as well as evolving strategies to evade the host immune system. The net effect of these ecological...
Human activities are causing profound changes to the global environment, yet the potential consequences of these changes on rising atmospheric carbon dioxide and climate change are not well understood. Improving our understanding of these processes requires an enhanced awareness of how global ecosystems are changing and how these changes affect...
Prairies were once the dominant vegetation type in Oregon's Willamette Valley. Land use conversion, fire suppression, succession, and invasive species have reduced Willamette Valley prairies to less than 1% of their historical area. The remnant prairies that persist today are small in size and are highly fragmented. Marginal strips of...
National Forest management in the Pacific Northwest is shifting
from a focus on commodity production to ecosystem management, in which
the health of the entire forest ecosystem is considered, rather than that
of a few key species. Ecosystem management includes retention of some
live trees following timber harvest (green-tree retention)...
Changes in ocean conditions influenced by climatic fluctuations have lead to changes in individual species distributions, which alter the diversity, communities and species interactions across marine ecosystems worldwide. Assessing the species composition and identifying regions and habitats that can safeguard the persistence of biota are critically important. In this dissertation,...