Tree growth and soil nutrient responses to prescribed underburning were determined for a period of up to 12 years at four sites in northcentral and central Oregon ponderosa pine stands (Pinus ponderosa Dougl. ex Laws).
Differences reported are significant at a = 0.10. During the first 4-growing-season-measurement period after
underburning,...
Management practices following forest harvest can affect long-term soil productivity through alteration of soil carbon (C) and nitrogen (N) pools, but processes contributing to change are poorly understood. I assessed effects of three levels of logging-debris retention in combination with initial or annual applications of competing vegetation control (CVC) following...
The effect of physical factors such as soil structure, bulk density, parent material, and topographic variables on soil C and N dynamics and ectomycorrhizal inocululu
potential in forests of southwest Oregon were investigated In the high-elevation white fir (Abies concolor (Gord. & Glend.) Lindl.) zone, two old poorly-vegetated clearcuts with...
Red alder (Alnus rubra Bong.) seedlings fertilized with NH4NO3 or inoculated with a pure culture Fran/cia and inoculated with live or dead spores of the mycoirhizal fungus Alpova diplophloeus (Zeller & Dodge) Trappe & Smith were grown in a growth
chamber or in a greenhouse for six months Frankia inoculation...
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...
Dissolved organic matter (DOM) plays an important role in transport of C and essential nutrients such as N, P and S. DOM is also critical for the formation of soil organic matter (SOM), which is the largest terrestrial C pool. Nonetheless, we lack a basic understanding of what controls immobilization...
The objectives of this research were to study: a) the effect of thinning and treatments consisting of pruning
and multinutrient fertilization on aboveground biolnass increment, growth efficiency (GE), and foliar nutrients;
b) the influence of topoedaphic variables (soil nutrients, slope, aspect, and rock content) and foliar nutrients on both leaf...
Most soil organic C is in a stable form, associated with clay minerals in the upper soil profile. Upon environmental and land-use changes, stable soil C is subject to losses, which influence the global C cycle and the productivity of terrestrial ecosystems. However, mechanisms controlling soil C destabilization are not...
To determine whether shading increases drought-induced
root mortality by changing the chemical
composition of roots, I conducted an experiment in which
high and low light treatments in combination with high
and low soil moisture treatments were applied to
seedlings of Douglas-fir (Pseudotsuqa menziesii Mirb.
Franco). Because synthesis of suberin (a...
Low-permeability geologic units may offer significant chemical and hydraulic protection of adjacent aquifers, and are important for managing groundwater quality, especially in areas with significant non-point source contamination. Nitrate in the Willamette Valley is attenuated across the Willamette Silt, a semi-confining unit overlying a regionally important aquifer. To quantify the...