Few landscapes are immune to invasion by exotic plant species. The forested landscape in the western Cascade Range of Oregon appears to have some barriers to invasion, but the extensive road network provides a corridor and habitat for a suite of exotic species to enter and become established. This study...
Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range...
In the Oregon Cascade Range, conifer encroachment has reduced the extent of mountain meadows by as much as 50% since the mid-1940s. Although encroachment results in a general decline of meadow species abundance and diversity, species differ in their sensitivities to encroachment: some show rapid declines whereas others persist in...
The seasonal duration of snow cover is a primary factor influencing the patterns of vegetation in high subalpine and alpine environments, but little is known concerning the responses of plant reproduction and
seedling recruitment to gradients of snow-release. Vegetation patterns of a high subalpine site in the Oregon High Cascades...
This thesis examines factors limiting understory herb presence and flowering in young second-growth Douglas-fir (Pseudotsuga menziesii) forests on the west side of the Cascade Mountains, Oregon, USA. I studied the belowground effects of canopy trees on understory herbs and shrubs in old-growth forests using trenched plots from which tree roots...
Montane meadows comprise less than 5% of the landscape of the western Cascades of Oregon, but they provide habitat for diverse species of plants and pollinators. Little is known about plant-pollinator network structure at these sites. This study quantified plant-pollinator interactions over the summer of 2011, based on six observations...
Defensive chemical and nutritive quality of young leaves were measured for 72 individual trees of Chrysolepis [Castanopsis] chrysophylla in conjunction with light intensities of two different stand types and population numbers of Habrodais grunus herri in the Cascade mountains of Oregon. Leaves were collected in the spring and leaf characteristics...
I compared transpiration among different types of forest stands in the western Cascades of Oregon. The three major questions were: 1) How does transpiration compare between a young and old stand and why? 2) Does diversity of overstory trees affect transpiration? and 3) How is transpiration related to stream flow?...
Reforestation-based restoration of severely burnt plantations is one of the primary management activities following wildfire on U.S. federal lands. Restoration effects on early-seral plant and cryptogam communities have not been documented. The objectives of this study were, in severely burnt plantations two to four years post-fire, to examine the: (1)...
Sixteen understory plant communities in the riparian zones of small streams are identified and described. They range from pioneer communities on gravel and rock to well-developed shrub communities on flood
plains and terraces. Several other vegetation types are discussed. Distribution of communities within the riparian zone is also discussed. A...