Study objectives were to survey and compare physical and chemical characteristics of soils within two thirdorder montane riparian ecosystems: a 500-year old Douglas fir (Pseudotsuga menzlesii) forest at Mack Creek, and a mature red alder (Alnus rubra) forest occupying a 35-year old clearcut at Quartz Creek, both near Blue River,...
Denitrification, the biological or chemical reduction of ionic nitrogen oxide or dinitrogen, has not been widely studied in forest ecosystems despite widespread interest in other facets of the forest nitrogen economy. This study had three main objectives: to determine whether potential for denitrification exists in forest riparian and hill slope...
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare.
Consequently, long-term effects of fire on soils are often hypothesized from
short-term effects. In a chronosequence study, I studied 24 western Cascades
(Oregon) forest stands thought to...
Fire history and fire regimes were reconstructed for a 450 km² area in the central
western Oregon Cascades, using tree-ring analysis of fire scars and tree origin years at
137 sampled clearcuts. I described temporal patterns of fire frequency, severity, and size,
and interpreted topographic influences on fire frequency and...
Forest roads constructed in steep mountain landscapes have been associated with a
number of effects on hydrologic and geomorphic processes. This research examined the
effects of forest roads on the flow of water and sediment in drainage basins in the Cascade
range of western Oregon. A study conducted at the...
This study examined the effect of fire regime on coarse woody debris (CWD) mass using a combination of field data and modeling. The objectives were to use field sampling to determine how CWD differs between two areas that have had different fire regimes, and investigate how fire frequency and severity,...
Forest floor vertebrate species presence and abundance may be influenced by the volume and cover of coarse woody debris (CWD) in managed forests. I studied macro- and microhabitat associations of vertebrate species in 18 closed-canopy stands ranging in CWD volume from 14 to 859 m3/ha. Pitfall traps were used to...
The purpose of this study was to assess how growth of young to mature Douglas-fir
(Pseudotsuga menziesii (Mirb.) Franco) and western hemlock (Tsuga heterophylla (Raf.) Sar.)
in mixed stands was influenced by the presence of residual trees. Fourteen paired plots with
and without residual trees were examined in a retrospective...
Quantifying and modeling processes involved in the global carbon cycle is important to evaluate the temporal and spatial variability of these processes and understand the effect of this variability on future response to changing climate and land use patterns. Biomass accumulation and Net Primary Productivity (NPP) are large components of...
Tree species directly and indirectly affect soil nutrient cycles. I sought to characterize soils and foliage associated with four common canopy tree species (Douglas-fir, western hemlock, western redcedar, and bigleaf maple) in mixed-species old-growth forests of the Oregon Coast Range and to determine whether and how soils differ among the...