Landscape positions have been used to determine soil properties. My soil study in Monteverde on the Pacific slope of Costa Rica was designed to examine soil-landscape relationships for sites with various land use histories and management. Soil pits were dug at Nacimiento y Vida, Crandell, Curi-cancha, La Calandria, and Finca...
In intensively managed forest plantations in the northern Oregon Coast Range, herbicides are often applied during site preparation and early stand regeneration to reduce competition for resources for planted conifer seedlings. In addition to reducing competition for crop trees, herbicide applications may affect soil processes including decomposition and nutrient cycling,...
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Chapter 2: Effects of Intensive Forest Management and Wildlife on Decomposition and Soil
Forest soils contain a substantial portion of global terrestrial carbon stores. Forest management can influence the soil carbon pool and how soil organic matter functions. The long-term productivity of forests is an ongoing goal where land managers utilize biomass and timber. A site-specific understanding of intensively managed forests can ensure...
Forest soils and topography have long been known to influence forest productivity in complex terrain such as Oregon’s Coast Ranges. Incorporating physical site characteristics into predictions of forest growth and yield, however, has been problematic because of the high spatial variability of soil properties and the challenges associated with representing...
Soils and other resource programs in both public land management agencies and private industry are continually being adapted to the challenges of evolving knowledge and experience in the field of forestry. This dissertation explores new ways of thinking about and using soils information in forest planning and management, with a...
Forest harvest persists as one of the most globally important industries, and crucially provides raw wood products for both building and fuel materials. Mechanistically complex abiotic and biotic processes curb ecosystem recovery following timber harvest and it is of great importance to understand the effects of this practice on biogeochemical...
Soil properties may hold the key to improved predictions of soils during digital soil mapping (DSM), which has developed with a focus on environmental factors external to soil. The spatial variability in soil properties was modeled across Malheur National Forest in eastern Oregon as an approach to improve DSM. The...
Fuel accumulation and climate shifts are predicted to increase the frequency of high-severity fires in ponderosa pine (Pinus ponderosa Dougl. ex Laws) forests of central Oregon. The combustion of fuels containing large downed wood can result in intense soil heating, alteration of soil properties, and mortality of microbes. Previous studies...
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4.1. Forest floor and mineral soil differences
Soil dissolved organic carbon (DOC) is a small but crucial part of the forest carbon cycle. Characterizing the relationship between detrital inputs and soil DOC chemistry is crucial to understanding the ultimate fate of root carbon, fallen wood and needles. Chemical differences in the DOC pool may help to explain...
Forest management is rapidly undergoing a transformation from a discipline based on efficient commodity production to one for multiple uses, especially on federally managed land in the United States. This new management paradigm has challenged silviculturists to develop and adapt forest management techniques that can deal with increased demands. Using...
Molybdenum is an essential component of biogeochemical cycling, most notably as a component of the nitrogenase enzyme used in biological nitrogen (N) fixation. While the important role of phosphorus (P) in limiting N fixation in ecosystems has been well documented, occurrence and prevalence of molybdenum (Mo) limitation is largely unknown....
Ecosystem nitrogen (N) supply strongly influences the availability and cycling of other essential nutrients in temperate forests, especially calcium (Ca). Short-term additions of N that exceed ecosystem demands often increase dissolved nitrate fluxes and decrease soil pH, which can stimulate soil Ca loss. However, the long-term effects of high N...
An understanding of the factors that influence surface erosion from roads is necessary to prevent and mitigate sediment production from forest roads. This study investigated the impacts of log truck traffic and road hydrology on sediment yield from ten forest road segments in the foothills of the Cascade Mountains of...
Prior to 2005, ammonia oxidation, the first step of nitrification, was thought mediated mainly by ammonia-oxidizing bacteria (AOB). However, the discovery of Thaumarchaeota carrying the genes coding for the ammonia monooxygenase (AMO) enzyme led to the discovery that ammonia-oxidizing archaea (AOA) also contribute to nitrification. Despite the uptick in studies...
The over-arching theme of this work is that soil data affect the performance and realism of vegetation models with particular focus on their ability to predict or explain disturbances such as fire or disease. We tested the sensitivity of the Excel version of the 3-PG model to soil properties and...
Emissions largely associated with the combustion of fossil fuels and agriculture has caused elevated atmospheric deposition of nitrogen (N) and sulfur (S) throughout much of the developed world. Increased atmospheric deposition of N and S can lead to soil and surface water acidification and affect forest soil nutrient supply. The...
Ectomycorrhizal fungi (EmF) form symbioses with trees. These symbioses profoundly influence forest ecology. Certain EmF form specialized profusions of hyphae, known as ectomycorrhizal fungal mats (mats) which are visible to the naked eye, alter forest soil biogeochemistry, substantially contribute to soil microbial biomass/respiration and support unique microbial communities. Piloderma and...
Forests are one of the largest repositories of terrestrial C. Understanding factors that drive organic matter transformations and nutrient efflux from these systems is therefore highly important. Temperate forests are of particular significance due to the large fraction of C that is stored below ground in the soil. Characterizing nutrient...
Nitrification and denitrification are major biological processes transforming nitrogen (N) in soils to plant available N, highly leachable nitrate (NO₃⁻) and gaseous N oxides. Although many studies in the past have studied N cycling communities, the effect of increased N inputs on ammonia-oxidizer and denitrifier population dynamics is still under...
Background information is presented that provides historical perspectives on the field of mycology in the Pacific Northwest and its role in forest management. The series of events and decisions that have led to previous studies (or lack of studies) in the field also dictate the directions of current research. Culture,...
The link between aboveground net primary productivity (ANPP) and resource gradients generated by complex terrain (solar radiation, nutrients, and moisture) has been established in the literature. Belowground ecosystem stocks and functions, such as soil organic carbon (SOC), dissolved organic carbon (DOC), and belowground productivity have also been related to the...
Mat-forming ectomycorrhizal (EcM) fungi represent a prevalent constituent of many temperate forest ecosystems and create dramatic changes in soil structure and chemistry. EcM mat soil have been shown to have increased microbial respiration rates and have been hypothesized to harbor unique assemblages of fungi and bacteria. The objectives of this...
Globally, the forestry sector is the second largest contributor of greenhouse gases, and sustainable forest management is a major target of international environmental policy. However, there is the assumption underlying many policy recommendations that an increase in above-ground carbon stocks correspond to long term increases in ecosystem carbon stocks, the...
Calcium (Ca) is an essential macronutrient that is increasingly recognized as a biogeochemical factor that influences ecosystem structure and function. Progress in understanding the sustainability of ecosystem Ca supply has been hampered by a lack of information on the various forms and pools of Ca in forest ecosystems. In particular,...
The increased demand for wood and fiber from a continually shrinking land base has resulted in the use of intensively managed forest plantations. The concentration of timber production on the most suitable sites allows the world's demand for forest products to be met on less land and enable native forests...
This publication is a reference guide for forest soils productivity and management. Main topics include (1) understanding and managing risk, (2) soil characteristics that affect productivity, (3) soil survey information for forestland managers/management of soil erosion, (4) managing mass wasting risk, (5) managing soil disturbance, and (6) maintaining adequate nutrient...
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...
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...
Dry coniferous forests in the western United States are experiencing severe wildfires, insect outbreaks, forest disease epidemics and a growing presence of invasive species. Policies strongly emphasize reducing hazardous fuels at the Wildland Urban Interface (WUI) where communities and forests intersect. However, these areas present restoration challenges as they tend...
The links between forests, streamflow, and climate are poorly understood. Despite hundreds of studies over the past 60 years, fundamental questions of forests' effects on the hydrologic cycle remain unanswered. The hydrological cycle involves mutually-dependent biological and physical processes that operate at multiple scales of time and space, and this...
One of the basic questions facing transportation planners and road managers is how to provide and maintain a road system that provides efficient access to the forest while limiting adverse effects roads can have on water and soil resources. The purpose of this study is to develop decision support models...
I examined factors regulating decomposition rates of red alder (Alnus rubra)) and Douglas-fir (Pseudotsuga menziesii) leaf litter in Coast Range riparian areas in western Oregon. Overall, this study was designed to examine the influence that leaf litter quality characteristics and decomposition site treatment have on decomposition rates, to provide a...
Soils are the largest terrestrial pool of carbon, therefore it is critical to understand
what controls soil carbon efflux to the atmosphere in light of current climate uncertainty.
The primary efflux of carbon from soil is soil respiration which is typically categorized
into autotrophic and heterotrophic respiration. These two components...
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...
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...
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...
Predictive Soil Mapping (PSM) has recently become an attractive method for soil scientists wishing to develop a more objective and efficient approach to mapping soils. Due to the potential PSM has for reducing the effort to produce soil maps, as well as its ability to improve the classification accuracy of...
Sustainable management of planted forests requires maintenance of soil function
to promote 1) root growth; 2) storage and cycling of water and nutrients; 3) optimal gas
exchange; and 4) biological activity. Soil quality measurements can be used to monitor
short- and long-term changes in these soil functions, allowing managers to...
Soils are a globally significant carbon (C) pool and have the potential to respond to elevated CO2 and environmental changes through positive feedback cycles that enhance the turnover of soil organic matter (SOM). Understanding the mechanisms governing the turnover of SOM is particularly important for modeling the fate of C...
Carbon sequestration in tropical secondary forests growing in all climates must be quantified to understand their potential role in adaptation and mitigation strategies of global climate change. Total aboveground biomass (TAGB), soil carbon, and total ecosystem carbon (TEC) were measured in 54 secondary forests growing along a broad bioclimatic gradient...
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...
Silvicultural canopy gaps are emerging as an alternative management tool to accelerate development of complex forest structure in young, even-aged forests of the Pacific Northwest. I investigated patterns of nitrogen (N) availability along transects through 0.1 and 0.4 ha silvicultural gaps in three 50-70 year old Douglas-fir forests of western...
Understanding how N availability influences base cation stores is critical for long-term ecosystem sustainability. Indices of nitrogen (N) availability and the distribution of nutrients in plant biomass, soil, and soil water were examined across ten young, unpolluted Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Coast Range spanning a three-fold soil...
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...
Forest roads produce fine sediment with traffic during wet weather. If the forest road is connected to a stream it can be a source of turbidity and fine sediment that may be detrimental to aquatic organisms especially salmonids.
The goal of this work was to investigate turbid runoff during wet-weather...
Belowground carbon (C) storage and quality of soil organic matter (SOM) in
forest soils have implications for sustainable forest management and C sequestration,
but how these pools change in response to management is poorly understood. I
investigated whether fertilization and competing vegetation control, applied alone or
in combination early in...
Disturbance, whether natural or of human origin, modifies to varying degrees
many ecosystem attributes. Fire is a natural process in the montane forests of southern
Oregon but for much of the 20th century fire was viewed as an apocalypse and thus
fervently suppressed. Effective natural resource management requires an
understanding...
The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations...
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...
This research addressed the opportunity to obtain baseline data for both stream chemistry and soil resources for an intensively managed forest watershed, encompassed by the North and South Forks of Hinkle Creek Watershed Research and Demonstration Area Project near Sutherlin, Oregon. A solid representative database for both stream and soil...