Fire exclusion has been associated with structural and compositional changes
in many upland forests of the western United States, but little is known about the
impacts on riparian forests, portions of the landscape protected for habitat and water
quality. For this study, I characterized the historic disturbance and tree recruitment...
In the Coast Range of western Oregon, some natural resource managers are converting red alder-dominated riparian areas to conifers to increase the future source of in-stream large wood for salmonid habitat. However, studies in Alaska have shown red alder-dominated riparian areas support greater invertebrate biomass compared to conifer-dominated areas. In...
Fire is the dominant disturbance process in western U.S. forests, and although effects of fire in upland forests are relatively well-studied, there is little information about fire effects on riparian forests, critical areas of the landscape for both habitat and water quality. This dissertation examines different aspects of fire effects...
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David E. Hibbs
Fire is the dominant disturbance process in western U.S. forests, and
Climate change and the increase in meteorological drought have generated global concern over the persistence of ecosystems already in decline from decreased moisture. Evidence suggests dryland ecosystems have been more impacted by drought because of their tightly coupled growth-water relationships and high sensitivity to environmental shift. Removal of competing vegetation...
Food webs consist of a combination of bottom-up (resource-driven) and top-down (predator-driven) effects. The strength of these effects depends on the context in which they occur. I investigated food web (trophic) relationships between wolf (Canis lupus) predation, elk (Cervus elaphus) herbivory, aspen (Populus tremuloides Michaux) recruitment, and fire. The study...
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David E. Hibbs
Food webs consist of a combination of bottom-up (resource-driven) and top
In western Oregon, hardwood trees occupy 20% of the
timberland but account for less than 1% of the timber
harvest. Information about how to manage them effectively
is limited.
The objective of this study was to examine: 1)
effect of thinning on tree growth, plant moisture stress,
and crown cover...
Allochthonous litter inputs are a primary source of organic matter in low-order
forested streams. A major component of this litter moves through small streams as fine
particulate organic matter (FPOM). Litter decomposition has been well studied, but few
studies have examined benthic FPOM (FBOM) dynamics. The purpose of this study...
Despite the critical ecological roles of structural features in forests, ecologically
relevant quantitative measures of structure that allow comparisons among forest stands
are still limited. A new index, the structural complexity index (SCI), was developed to
characterize and compare the structural complexity of different forests. Point patterns
of stem-mapped trees...
The effect of solution nitrogen (N) and phosphorus
(P) concentrations on biomass production and N₂ fixation
of red alder (Alnus rubra Bong.) seedlings grown in
perlite-filled pots in a climate controlled growth room
were studied. Nodulated seedlings were subjected to 12
different nutrient solution combinations of nitrogen and
phosphorus and...
Riparian areas that can be used as reference sites on which to base goals of vegetation restoration have not been documented in the Oregon Coast Range. I examined the composition and distribution of unmanaged riparian overstories in the central Oregon Coast Range along nine streams which have experienced minimal disturbance...
