Open Access. Powered by Scholars. Published by Universities.®

Soil Science Commons

Open Access. Powered by Scholars. Published by Universities.®

Portland State University

Series

Discipline
Keyword
Publication Year
Publication

Articles 1 - 10 of 10

Full-Text Articles in Soil Science

Winter Climate Change Affects Growing-Season Soil Microbial Biomass And Activity In Northern Hardwood Forests, Jorge Durán, Jennifer L. Morse, Peter M. Groffman, John L. Campbell, Lynn M. Christenson, Charles T. Driscoll, Timothy J. Fahey, Melany C. Fisk, Mryon J. Mitchell, Pamela H. Templer Jan 2014

Winter Climate Change Affects Growing-Season Soil Microbial Biomass And Activity In Northern Hardwood Forests, Jorge Durán, Jennifer L. Morse, Peter M. Groffman, John L. Campbell, Lynn M. Christenson, Charles T. Driscoll, Timothy J. Fahey, Melany C. Fisk, Mryon J. Mitchell, Pamela H. Templer

Environmental Science and Management Faculty Publications and Presentations

Understanding the responses of terrestrial ecosystems to global change remains a major challenge of ecological research. We exploited a natural elevation gradient in a northern hardwood forest to determine how reductions in snow accumulation, expected with climate change, directly affect dynamics of soil winter frost, and indirectly soil microbial biomass and activity during the growing season. Soils from lower elevation plots, which accumulated less snow and experienced more soil temperature variability during the winter (and likely more freeze/thaw events), had less extractable inorganic nitrogen (N), lower rates of microbial N production via potential net N mineralization and nitrification, and higher …


Accelerated Thermokarst Formation In The Mcmurdo Dry Valleys, Antarctica, Joseph S. Levy, Andrew G. Fountain, James L. Dickson, James W. Head, Marianne Okal, David R. Marchant, Jaclyn Watters Jul 2013

Accelerated Thermokarst Formation In The Mcmurdo Dry Valleys, Antarctica, Joseph S. Levy, Andrew G. Fountain, James L. Dickson, James W. Head, Marianne Okal, David R. Marchant, Jaclyn Watters

Geology Faculty Publications and Presentations

Thermokarst is a land surface lowered and disrupted by melting ground ice. Thermokarst is a major driver of landscape change in the Arctic, but has been considered to be a minor process in Antarctica. Here, we use ground-based and airborne LiDAR coupled with timelapse imaging and meteorological data to show that 1) thermokarst formation has accelerated in Garwood Valley, Antarctica; 2) the rate of thermokarst erosion is presently,10 times the average Holocene rate; and 3) the increased rate of thermokarst formation is driven most strongly by increasing insolation and sediment/albedo feedbacks. This suggests that sediment enhancement of insolation-driven melting may …


Water Track Modification Of Soil Ecosystems In The Lake Hoare Basin, Taylor Valley, Antarctica, Joseph S. Levy, Andrew G. Fountain, Michael N. Gooseff, John E. Barrett, Robert Vantreese, Kathleen A. Welch, W. Berry Lyons, Uffe N. Nielsen, Diana H. Wall Jul 2013

Water Track Modification Of Soil Ecosystems In The Lake Hoare Basin, Taylor Valley, Antarctica, Joseph S. Levy, Andrew G. Fountain, Michael N. Gooseff, John E. Barrett, Robert Vantreese, Kathleen A. Welch, W. Berry Lyons, Uffe N. Nielsen, Diana H. Wall

Geology Faculty Publications and Presentations

Water tracks are zones of high soil moisture that route shallow groundwater down-slope, through the active layer and above the ice table. A water track in Taylor Valley, McMurdo Dry Valleys, was analysed for surface hydrogeological, geochemical, and biological characteristics in order to test the hypothesis that water tracks provide spatial structure to Antarctic soil ecosystems by changing the physical conditions in the soil environment within the water tracks from those outside the water tracks. The presence of the water track significantly affected the distribution of biotic and abiotic ecosystem parameters: increasing soil moisture, soil salinity, and soil organic matter …


Using Environmental Variables And Soil Processes To Forecast Denitrification Potential And Nitrous Oxide Fluxes In Coastal Plain Wetlands Across Different Land Uses, Jennifer L. Morse, Marcelo Ardón, Emily S. Bernhardt Jun 2012

Using Environmental Variables And Soil Processes To Forecast Denitrification Potential And Nitrous Oxide Fluxes In Coastal Plain Wetlands Across Different Land Uses, Jennifer L. Morse, Marcelo Ardón, Emily S. Bernhardt

Environmental Science and Management Faculty Publications and Presentations

We examined relationships between denitrification (DNF) and nitrous oxide (N2O) fluxes and potentially important chemical and physical predictors to build a predictive understanding of gaseous N losses from coastal plain wetlands. We collected soil, gas, and pore water samples from 48 sampling locations across a large (440 ha) restored wetland, an adjacent drained agricultural field, and nearby forested wetlands every two months over two years. In summer and fall 2007, we measured soil DNF potential (21.6-3560 mg N m-3 d-1) and N2O efflux (-4.36-8.81 mg N m -2 d-1), along with 17 predictor variables. We developed statistical models for the …


Historical Vegetation Of Central Southwest Oregon, Based On Glo Survey Notes : Final Report To Usdi Bureau Of Land Management, Medford District, O. Eugene Hickman, John A. Christy Oct 2011

Historical Vegetation Of Central Southwest Oregon, Based On Glo Survey Notes : Final Report To Usdi Bureau Of Land Management, Medford District, O. Eugene Hickman, John A. Christy

Institute for Natural Resources Publications

Historical vegetation at the time of European settlement is of great interest to both the public and land managers, but is poorly documented. One source of data are the earliest land survey records of the General Land Office (GLO). Rectangular township surveys in Southwest Oregon were initiated in the mid 1850’s as settlers began to claim homesteads in the Bear Creek Valley surrounding what is now Medford. We examined GLO land survey field notes and plats (maps) accompanying the surveys, transcribed GLO landscape data into an Access database, and classified the data set into very general vegetation types for mapping. …


Foliar Nutrient Concentrations Related To Soil Sources Across A Range Of Sites In The Northeastern United States, Melissa S. Lucash, Ruth D. Yanai, Joel D. Blum, B. B. Park Jan 2011

Foliar Nutrient Concentrations Related To Soil Sources Across A Range Of Sites In The Northeastern United States, Melissa S. Lucash, Ruth D. Yanai, Joel D. Blum, B. B. Park

Environmental Science and Management Faculty Publications and Presentations

Understanding the supply of nutrients from various soil sources and the sensitivity of tree species to soil nutrient availability is critical for predicting the effects of declines in base cations due to acid rain and forest harvesting on forest health and productivity. We collected soil samples from 19 sites in the northeastern United States, chemically analyzed them using a sequential extraction procedure, and compared them to the chemical composition of foliage of the dominant tree species. Concentrations of Ca and Mg in foliage were correlated with exchangeable Ca and Mg concentrations in the upper mineral soil; for most tree species …


Similarity Of Nutrient Uptake And Root Dimensions Of Engelmann Spruce And Subalpine Fir At Two Contrasting Sites In Colorado, Melissa S. Lucash, Ruth D. Yanai, Karis J. Mcfarlane, Sarah E. Kulpa, Dustin M. Wood Oct 2009

Similarity Of Nutrient Uptake And Root Dimensions Of Engelmann Spruce And Subalpine Fir At Two Contrasting Sites In Colorado, Melissa S. Lucash, Ruth D. Yanai, Karis J. Mcfarlane, Sarah E. Kulpa, Dustin M. Wood

Environmental Science and Management Faculty Publications and Presentations

Nutrient uptake capacity is an important parameter in modeling nutrient uptake by plants. Researchers commonly assume that uptake capacity measured for a species can be used across sites. We tested this assumption by measuring the nutrient uptake capacity of intact roots of Engelmann spruce (Picea engelmanni Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) at Loch Vale Watershed and Fraser Experimental Forest in the Rocky Mountains of central Colorado. Roots still attached to the tree were exposed to one of three concentrations of nutrient solutions for time periods ranging from 1 to 96h, and solutions were analyzed for ammonium, …


Economics Of Soil Conservation Adoption In High-Rainfall Areas Of The Ethiopian Highlands, Menale Kassie, Stein Holden, Gunnar Köhlin, Randall Bluffstone Mar 2008

Economics Of Soil Conservation Adoption In High-Rainfall Areas Of The Ethiopian Highlands, Menale Kassie, Stein Holden, Gunnar Köhlin, Randall Bluffstone

Economics Faculty Publications and Presentations

This study measures the impact of fanya juu bunds (an important soil and water conservation technology and the most popular type of contour bund in east Africa) on the value of crop production in a high-rainfall area in the Ethiopian highlands using cross-sectional multiple plot observations. We applied switching regression, stochastic dominance analysis (SDA), and decomposition and propensity score matching methods to ensure robustness. The switching regression, SDA, and decomposition analyses relied on matched observations, which was important because regression and SDA often do not ensure that comparable plots with conservation technology (conserved) and plots without (unconserved) actually exist in …


Response Of Sagebrush Steppe Species To Elevated Co2 And Soil Temperature, Melissa S. Lucash, Blake Farnsworth, William E. Winner Jan 2005

Response Of Sagebrush Steppe Species To Elevated Co2 And Soil Temperature, Melissa S. Lucash, Blake Farnsworth, William E. Winner

Environmental Science and Management Faculty Publications and Presentations

Elevated atmospheric CO2 may cause long-term changes in the productivity and species composition of the sagebrush steppe. Few studies, however, have evaluated the effects of increased CO2 on growth and physiology of species important to this ecosystem. Since the response of plants to elevated CO2 may be limited by environmental factors, soil temperature was also examined to determine if low soil temperatures limit CO2 response. To determine how CO2 and soil temperature affect the growth of species native to the sagebrush steppe, bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey], Thurber needlegrass (Stipa thurberiana Piper), …


The Role Of Soil Test Information In Reducing Groundwater Pollution, Ronald A. Fleming, Richard M. Adams, David E. Ervin Jul 1998

The Role Of Soil Test Information In Reducing Groundwater Pollution, Ronald A. Fleming, Richard M. Adams, David E. Ervin

Economics Faculty Publications and Presentations

Testing soils for nutrients is expected to improve groundwater quality. However, it is unknown whether soil testing will improve groundwater quality sufficiently to decrease the demand for direct regulation of agricultural practices. Focusing on an irrigated agricultural region in eastern Oregon, the economic and environmental aspects of soil testing are assessed using a spatially distributed, dynamic simulation model which links economic behavior with the physical processes that determine groundwater quality. Results indicate that soil testing of all fields increases farm profits and reduces groundwater nitrate concentration. However, the benefits are small in terms of potential improvements in groundwater quality.