Piliostigma reticulatum and Guiera senegalensis are two native shrubs that
coexist with row crops in parkland systems of the Sahel of Africa. Although
permanently green all year around in soil depleted in nutrients and dry for a nine-month
period, these shrubs have been largely overlooked. Conventional management of these
shrubs...
The objective of this study was to examine the variation among ammonia-oxidizing and denitrifying communities in soils of a natural Fennoscandian boreal forest and of a forest with a long history of fertilization with different levels of nitrogen (N), and to examine whether there are any changes in the microbial...
The objectives of this thesis were to evaluate the responses of soil microbial communities to physical and chemical disturbances, and associate these responses with soil functional stability and changes in soil quality. The first study consisted of application of heat shocks (HS) to soils with contrasting land use history to...
Ectomycorrhizal (ECM) fungi of the genera Piloderma and Ramaria form dense hyphal mats in the organic and upper mineral soil layers, respectively, in coniferous forest floors of the Pacific Northwest. Previous studies have determined that fungal mats change the chemical, physical, and biological properties of the soil within. Little information...
Land managers, scientists, and the interested public are confronted with uncertainty about the impacts of salvage logging on soil productivity. In recent years, stand-replacing wildfires in the western United States have increased in frequency, prompting the need to evaluate the effect of post-fire treatments on forest ecosystem recovery. This study...
Dense hyphal mats formed by ectomycorrhizal (EcM) fungi are prominent features in Douglas-fir (Pseudotsuga menziesii) forest soils and have been estimated to cover up to 40% of the forest floor in some stands. Although previous studies have examined various aspects of EcM fungi, little is known about their associated microbial...
Sagebrush steppe ecosystems in the Great Basin have become increasingly threatened by the proliferation of cheatgrass (Bromus tectorum L.), an invasive annual grass. Diverse sagebrush and perennial bunchgrass landscapes can be converted to homogenous cheatgrass grasslands mainly through the effects of fire. Although the consequences of this conversion are well...
Changes in the type and amount of plant inputs can occur gradually, as with succession, or rapidly, as with harvesting or wildfire. With global change it is anticipated that both gradual and immediate scenarios will occur at increasing frequency. Changes in vegetation inputs alter the quality and quantity of soil...
The Oregon Long-Term Soil Quality Project was initiated to identify soil
properties that respond rapidly to alternative management practices. Such practices
included winter cover cropping, which was implemented at two experimental research
stations and several grower fields throughout the Willamette Valley. The goal of this
thesis was to identify the...
Most carbon (C) transformations in soil are carried out by a diverse and complex soil microbial community. The size and composition of the soil microbial community is determined by poorly understood interactions between the quantity and chemical composition of plant inputs, as well as climate. Given the metabolic diversity of...