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
The use of mechanized harvest equipment has been
increasing as an economical method to harvest small diameter
timber. While the use of this equipment is increasing,
little is known about associated soil compaction. In
particular, little information exists on soil compaction
caused by feller--bunchers.
This study measured soil compaction caused...
Shovel logging is a relatively new ground-based method of yarding tinther. It involves moving logs from stump to landing by successive swinging with a hydraulic excavator modified into a log loader by replacing the shovel bucket with a grapple. Loaders used in shovel yarding can weigh in excess of 100,000...
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...
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...
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...
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...
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...
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...
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...
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....
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...
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...
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...
The study was conducted over approximately 191,000 acres in central Klamath County, Oregon. The research had three objectives: first, to describe and classify the seral and near-climax vegetation by using polyclimax principles; secondly, to determine the southern extension of five plant associations and one plant associes as previously described by...
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...
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...
The understory vegetation was sampled in eight plant communities
of a Douglas-fir ecosystem to determine the organic matter
production and mineral composition.
Four sample sites were selected in each plant community and
the understory vegetation sampled using the method of quadrats of
successively increasing size. All herbaceous plants were separated...
Humus is one of the important factors controlling the soil
formation process. The nutrients released from it during the decomposition
process also affect the growth and reproduction of the
forest. The type of humus formed is influenced by the nature of the
forest litter and the environment in which it...
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...
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...
The variability of selected physical, chemical, and morphological
soil properties in two landtype mapping units on'the Rogue River National
Forest in southwestern Oregon was studied.
The objectives of the study were (i) to quantify soil variability
in several soil resource inventory mapping units, (ii) to explore methods
of describing soil...
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 strength of both undisturbed and compacted soils from 10 sites
in the slide-prone Tongass National Forest in SE Alaska were studied.
Index property tests were also conducted on disturbed samples. The
index tests included natural water content, Atterberg Limits, specific
gravity of solids, grain size distribution, and moisture-density relationship....
Measurements for water retention calculations and physical
characterization were made on skeletal and non-skeletal soils in
southwest Oregon. A new bulk density sampler was designed for the
physical characterization of the steep, skeletal soils commonly
encountered in this area. The new sampler and the techniques
required for the measurement and...
This study was undertaken to determine both the amount and the
spatial variability of sand, silt, clay, and six fractions of coarse
fragments in soils representing harsh sites for reforestation. Particle size data were collected because of their direct relationship to
water holding capacity and the plantability and survivability of...
Many miles of roads are built in the Pacific Northwest Forests to provide access for logging and fire protection. Logging roads often cross steep mountainous terrain. Logging roads and the associated cut and fill slopes represent a discontinuity in the natural stress state in the soil mantle. These conditions result...
Total length and biomass of fungal mycelium in the soil of a young Douglas-fir stand in the central Oregon Coast Range were estimated over 27 months with the agar-film technique. In a second study, phenology and taxonomy of hypogeous (belowground) sporocarps were studied over 32 months in a nearby, young...
The purpose of this research was to determine if
overland flow and sediment production were different in
logged (on snow, frozen soil, and prescribed skid trails)
and nonlogged sites in a Pinus ponderosa Laws.!
Symohoricaroos albus Laws. community in the foothills of
the Wallowa Mountains in northeastern Oregon. To determine...
A Land Evaluation and Site Assessment (LESA) Model was
developed for the forested soils of Lane County, in western Oregon,
based on soil potential ratings and indexes of parcel size and
adjacent and surrounding land use conflict. Lane County's economy
is heavily dependent on resource production uses of land for...
Site preparation treatments are often used prior to the planting of clearcut
forest lands to improve planter access and to increase the number and quality of
planting spots. Most mechanical site preparation treatments alter the
configuration and material composition of surface soil materials, and can have
marked effects on soil...
Forest soils with low bulk densities are often considered less
susceptible to compaction than soils with higher bulk densities. The
objective of this study was to determine if soil strength controlled the
compression of soils with low bulk density. Four soils were selected
for this evaluation. Three of these were...
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...