Effects of small-scale disturbances on fecundity and growth rates of Linnaea
borealis L., Tiarella trifoliata L. var. unifoliata, and Trillium ovatum Pursh. were studied in
old-growth forests in the Tsuga heterophylla Zone on the west slope of the Cascade
Mountain Range of Oregon. Performance of each species was compared in...
This study assessed the effects of thinning on arthropod communities on understory plants in the Central Oregon Coast Range. Arthropods were sampled from five understory plants in five pairs of thinned and unthinned, young (50-80 yrs), managed Douglas-fir stands, from late May to mid-July of 1998. Vine maple (Acer circinatum),...
A simple debris-slide model, employing a digital elevation model (DEM) and geological data, was used in a geographic information system (GIS) to map slope stability in the Andrews Experimental Forest, located in the western Cascade Range in Oregon, USA. To evaluate the contribution of error in elevation to the uncertainty...
The growth potential of Douglas-fir, grand fir and western hemlock advance regeneration in the forest understory of Douglas-fir-dominated forests was investigated to detennine the feasibility of selection cutting systems in northwest Oregon. This study compared the growth of Douglas-fir, grand fir and western hemlock advance regeneration along a light gradient...
Seasonal and annual patterns of N fluxes and concentrations in streamwater in six conifer-dominated watersheds at the H.J. Andrews Experimental Forest, OR, were studied to gain insight into the factors that influence N retention in this ecosystem. Processes affecting N flux in streamwater differed between organic (DON) and inorganic (DIN;...
Viability analysis of well-selected focal species can complement other types of conservation planning by revealing thresholds in habitat area and landscape connectivity that may not be evident from ecosystem-level evaluations. I used focal species analysis of five carnivores to suggest conservation planning guidelines for the Rocky Mountains and adjacent areas...
A series of studies, in three western Oregon Douglas-fir plantations, was conducted to understand the physiological impacts of Swiss needle cast on Douglas-fir physiology. Four aspects of the disease complex were investigated: fungal colonization and assessment, plant-water relations, carbon assimilation and interaction with climate. Several techniques were developed and used...
My objectives were to investigate the correlation of height and diameter growth in young Douglas-fir (Pseudotsuga menziesii) plantations with stand density, and to determine the effects of stand density on the canopy boundary layer conductance (g[subscript]ac) and microclimate characteristics of young Douglas-fir plantations. I measured annual height (h) and diameter...
This study examined debris flows occurring in a 125 km² study area in the Blue River watershed in the western Cascade Mountains of Oregon over a 50-year period. Debris flow occurrence was found to be concentrated in a distinct zone of high activity occupying approximately half of the study area,...
These studies are part of the Demonstration of Ecosystem Management Options (DEMO) study, a program researching the effects of different levels and patterns of green-tree retention on ecological, economic, and social phenomena. We restricted our studies to the 15% basal area, evenly dispersed retention treatment. Our objectives were, first, to...
Field studies were conducted from 1996 to 1998 in three villages in a Highland watershed in Mae Hong Son Province, northern Thailand. The objectives of the study were to classify and define the fruit-based agroforestry cropping system and investigate
management activities used by villagers. In the first part of the...
Effects of partial understory removal on belowground and aboveground ecosystem properties were investigated in 5 and 15 yr old Douglas-fir (Pseudotsuga menziesll (Mirb.) Franco) experimental plantations in western Oregon. Seedling survival was not affected by understory removal at age 5 yr.
But through age 15 yr, understory removal increased seedling...
Coarse woody debris (CWD) decomposition in the Russian boreal forests of the southern taiga zone was studied at four sites located near St. Petersburg in Northwestern Russia, Krasnoyarsk in Eastern Siberia, lrkutsk in the Baikal region, and Khabarovsk in the Russian Far East. This study was part of a broader...
Application of N fertilizer is a common forest management practice in the Pacific
Northwest, yet the long-term influence of fertilization on forest soil properties is not well known. Although elevated N often increases mineralization of C and N from labile organic matter, negative effects have been documented in recalcitrant organic...
Intensive management of young-growth Douglas-fir plantations has emphasized volume growth over wood quality. A better understanding of the variables that affect wood quality is needed so that wood quality and stand yield can be systematically combined into a silviculture program. This experiment utilized two separate experiments to establish the relationship...
Thinning has the potential to increase structural diversity of managed forests for wildlife. During 1994-1996, I conducted experimental and observational studies using pitfall trapping to assess short-term and potential long-term effects of thinning on abundance and reproduction of forest-floor vertebrates in Douglas-fir (Pseudotsuga menzeisii) forests of the Oregon Coast Range....
During the last century, fire suppression, grazing, and climate change have caused sagebrush grasslands to be altered in both function and form; juniper and sagebrush dominate the landscape at the expense of herbaceous plants. Management efforts to reduce juniper and sagebrush overstory in order to enhance herbaceous components of the...
The tree species and size structure of 9l old-growth forests dominated by Douglas-fir
in central western Oregon was characterized using complete inventories of all trees larger than 20cm dbh over a mean area of 17.1ha at each site. Douglas-fir accounted
for over 75% of the total average basal area (39.1...
The spruce weevil (Pissodes strobi) is a serious pest of Sitka spruce in Oregon. Weevils cause damage by killing the leader of a tree, resulting in defects such as crooks and forks that can render the tree unmerchantable. In this study, spruce stands 16-25 years old were surveyed for weevil...
A mechanistic simulation model of nitrogen fixation in dead wood was developed to help synthesize knowledge, develop hypotheses, and estimate rates of nitrogen fixation in the Pacific Northwest. In this model nitrogen fixation is directly controlled by log substrate, temperature, moisture, and oxygen content. Respiration and diffusion of
oxygen indirectly...