Copyright (c) 2009 Grand Valley State University All rights reserved. http://scholarworks.gvsu.edu Recent documents in Scholar Works @ GVSU en-us Fri, 20 Nov 2009 05:34:55 PST 3600 http://scholarworks.gvsu.edu/peerscipub/3 http://scholarworks.gvsu.edu/peerscipub/3 Tue, 03 Nov 2009 13:00:23 PST Originally published in: J. N. Am. Benthol. Soc., 2006, 25(2):304-312Release of P from lake sediments may account for a significant portion of a lake's total P (TP) load. Previous studies using sediment cores showed that ;65% of the total P load entering Spring Lake, Michigan, came from the sediments, and that an alum concentration of 24 mg Al/L effectively inactivated P release in experimental sediment-core tubes. In 2004, we studied the influence of alum concentration and sediment resuspension on P release rates from the sediments. Based on laboratory incubations using alum concentrations of 0, 5, 10, 15, 20, and 25 mg/L, we determined that P release rates at alum concentrations 15 mg/L were no different than at release rates at concentrations of 25 mg/L. Resuspension of sediments substantially increased TP concentrations, even at high alum concentrations, but total soluble P concentrations remained low in the water when alum was present. Alum application may be an effective tool to reduce P flux from sediments in shallow lakes, but external P load reduction must accompany alum application to address the long-term impacts associated with cultural eutrophication. Alan D. Steinman http://scholarworks.gvsu.edu/gradprojects/3 http://scholarworks.gvsu.edu/gradprojects/3 Tue, 27 Oct 2009 12:10:19 PDT ANZBC software was written as a prototype to download small‐encoded files form Usenet servers. This software allows anything from a text document to a HD movie to be downloaded and decoded into a single file. Often this is a single file that is split into multiple small files and then compressed. Alexander J. Patterson http://scholarworks.gvsu.edu/gradprojects/2 http://scholarworks.gvsu.edu/gradprojects/2 Tue, 27 Oct 2009 12:10:18 PDT Today's world is experiencing constant and rapid change in all areas of life. Progress and technology are the catalysts for the change, and the result is a continuous turnover of knowledge. It is essential for educational institutions to keep pace with the changes in order to turn out students that meet local and national employment requirements. Educational institutions are in need of an assessment system to measure the ongoing effectiveness of disciplines, curricula, programs and courses. The assessment system will provide the tools to develop, implement, manage, maintain and evaluate the efficiencies of educational programs. The input will include past program requirements, national industry employment expectations, accreditation standards, model curriculum recommendations and student assessment/validation. The output will generate degree programs that keep up with change, validate the transfer of knowledge, meet accreditation standards, follow model curriculum guidelines and are consistent with current employment requirements. Dyana Polderdyk http://scholarworks.gvsu.edu/gradprojects/1 http://scholarworks.gvsu.edu/gradprojects/1 Tue, 27 Oct 2009 12:03:11 PDT Flex and Silverlight provide large Application Programming Interfaces (API's). Applications can be designed using a variety of architectures. The purpose of this paper is not to perform a complete comparison between Flex and Silverlight. To do such a comparison would require massive amounts of time and research. The purpose of this paper is to describe the design and implementation of the Silverlight photography framework project. Along the way this paper compares the Silverlight project to the Adobe Flex project and discusses the goals of each product. During the comparison many important similarities and differences between Silverlight and Flex technologies are discussed. David Roossien http://scholarworks.gvsu.edu/biopeerpubs/25 http://scholarworks.gvsu.edu/biopeerpubs/25 Fri, 23 Oct 2009 13:00:13 PDT Global climate change may impact the cycling of C, N, and S in forest ecosystems because increased soil temperatures could alter rates of microbially mediated processes. We studied the effects of temperature on microbial respiration and net N and S mineralization in surface soils from four northern hardwood forests in the Great Lakes region. Soil samples were incubated in the laboratory at five temperatures (5, 10, 15, 20, and 25°C) for 32 wk. Headspace gas was analyzed for CO2-C at 2-wk intervals, and soils were extracted to determine inorganic N and S. Cumulative respired C and mineralized N and S increased with temperature at all sites and were strongly related (r2 = 0.67 to 0.90, significant at P = 0.001) to an interaction between temperature and soil organic C. Production of respired C and mineralized N was closely fit by first-order kinetic models (r2 0.94, P = 0.001), whereas mineralized S was best described by zero-order kinetics. Contrary to common assumptions, rate constants estimated from the first-order models were not consistently related to temperature, but apparent pool sizes of C and N were highly temperature dependent. Temperature effects on microbial respiration could not be accurately predicted using temperature-adjusted rate constants combined with a constant pool size of labile C. Results suggest that rates of microbial respiration and the mineralization of N and S may be related to a temperature-dependent constraint on microbial access to substrate pools. Simulation models should rely on a thorough understanding of the biological basis underlying microbially mediated C, N, and S transformations in soil. Neil W. MacDonald http://scholarworks.gvsu.edu/biopeerpubs/24 http://scholarworks.gvsu.edu/biopeerpubs/24 Fri, 23 Oct 2009 12:47:38 PDT In a previous study, jack pine (Pinus banksiana Lambert) seedlings grown under pH 2.5 simulated rain had larger shoot/root ratios and altered nutrition compared with seedlings grown with pH 4.7 rain. The objective of this study was to determine if these differences in initial seedling characteristics produced long-term effects on survival or growth of outplanted seedlings. Significantly (P < 0.05) greater diameter increment (4.3 vs. 4.0 cm) between ages 6 and 10 of jack pine treated with pH 2.5 rain as seedlings was consistent with a carryover effect from the initial treatments. However, no differences between treatments in jack pine diameter, height, or survival persisted to age 14. Results support recent recommendations that extended measurement periods may be necessary to fully assess the long-term effects of pollutant increases or decreases on growth of immature trees. Neil W. MacDonald http://scholarworks.gvsu.edu/biopeerpubs/23 http://scholarworks.gvsu.edu/biopeerpubs/23 Fri, 23 Oct 2009 12:39:54 PDT Elevated soil temperatures may increase C loss from soils by accelerating microbial respiration and dissolved organic C leaching. We evaluated the effect of elevated soil temperatures on C losses from a forest Spodosol by incubating soil cores from surface (Oa + A + E) and subsurface (Bhs) horizons at two seasonal temperature regimes. One regime simulated the normal course of soil temperatures in northern lower Michigan, and the other simulated soil temperatures representing an amount of warming that might occur under some global warming theory calculations. We measured the amounts of CO2-C respired and dissolved organic C leached from the soil cores during a 33-wk period. Microbial respiration rates, after adjustment for variation in initial rates, were significantly increased by soil warming and were greater in surface than in subsurface horizons. Warming significantly increased cumulative C respired, with greater losses from surface soils ( 50 mg C g-1 C) as compared with subsurface soils ( 25 mg C g-1 C). Mean quantities of dissolved organic C leached, ranging from 2.3 to 3.2 mg C g-1 C, did not differ significantly by soil horizon or temperature regime. Increased microbial respiration in surface soil horizons was the process most responsive to soil warming in the Spodosol samples we examined. Whether this is a short-term effect that would disappear once pools of labile C are exhausted, or represents a long-term response to soil warming, remains uncertain. Neil W. MacDonald http://scholarworks.gvsu.edu/biopeerpubs/22 http://scholarworks.gvsu.edu/biopeerpubs/22 Fri, 23 Oct 2009 12:08:43 PDT We studied the establishment of native warm-season grasses on gravel mine spoils infested by spotted knapweed (Centaurea maculosa), an exotic perennial that is difficult to control on droughty, infertile sites. We applied factorial combinations of sewage sludge (o and 11.9 Mg ha−1 [5.3 tons ac−1]) and herbicide (none; 2,4-D; and glyphosate) to evaluate their effects on native grass establishment and on competition between native grasses and spotted knapweed. While native grasses were successfully established with all treatment combinations, sludge application reduced their densities. Warm season grass biomass subsequently increased rapidly on both sludge and control plots. Both herbicide treatments reduced density and biomass of knapweed during the first two years of the study, but glyphosate and sludge interacted to produce increased knapweed biomass during the third year. For this reason, it may be desirable to delay application of sludge amendments until warm-season grasses are well established in herbicide-treated areas. The response of knapweed to improved soil fertility was dependent on the degree of grass competition, and where this remained high, knapweed dominance was suppressed. While warm-season grasses appeared to compete successfully with spotted knapweed, additional control measures may be required to maintain grass dominance on this and similar knapweed-infested sites. Neil W. MacDonald http://scholarworks.gvsu.edu/biopeerpubs/21 http://scholarworks.gvsu.edu/biopeerpubs/21 Fri, 23 Oct 2009 11:44:46 PDT The Pigeon River drains a 16,765-ha agricultural watershed in western Ottawa County, Michigan and discharges into south-central Lake Michigan. Extensive areas of wetlands in the upper watershed were drained in the 1920s, causing significantly altered hydrology characteristics by flashy discharges during storms and periods of snowmelt. We studied stream chemistry and hydrology for a four-year period between September, 1996, and October, 2000, to determine water quality status, to estimate annual nutrient exports, and to evaluate the effects of different seasonal flow types. Results of our study confirmed that the upper reaches of the Pigeon River experience chronically degraded water quality, with contributions from both nonpoint and point sources. As a result, the watershed has high annual rates of nutrient export (approximately 10.8 kg ha-1 inorganic N and 0.25 kg ha-1 PO4-P). With the influx of groundwater, change in land use to forest, and development of natural stream channel characteristics in the lower mainstream, water quality at baseflow in this section of the Pigeon River improves to the point where coldwater fish populations should persist. Inputs of degraded water during high flows, however, produce periods of environmental stress and the fish population in the lower Pigeon includes only a low number of pollution-tolerant, warmwater species. Large summer storms are biologically stressful because of increased temperatures and reduced dissolved oxygen levels, while spring storms and snowmelt contribute substantially to total nutrient suspended solids exports. Efforts to improve water quality in this and similar agricultural watersheds need to emphasize major reductions in the nonpoint source inputs through substantial improvements in land and water management practices. Wetland restoration and implementation of other stormwater retention practices in such watersheds also are required to reverse the acute impacts of high stormwater discharges caused by past drainage and steam channelization. Neil W. MacDonald http://scholarworks.gvsu.edu/biopeerpubs/20 http://scholarworks.gvsu.edu/biopeerpubs/20 Fri, 23 Oct 2009 11:44:45 PDT Concern exists over the effects of interacting environmental stresses on the ecological integrity of temperate forests. Coincidence of sensitivity to drought, increasing occurrence of defoliation, and elevated pollutant deposition has produced speculation that northern hardwood forests may be susceptible to the increased climatic stresses projected for the Great Lakes region. The objective of our study was to examine relationships among environmental stress factors, vigor, mortality, and growth in northern hardwood forests located along a pollution-climate gradient in the Great Lakes region. Between 1987 and 1993, we quantified climatic variables, pollutant deposition, insect defoliation, and tree vigor and growth at five sites along this gradient. Drought and defoliation occurred to varying degrees during the study period. Symptoms of chronic environmental stress, such as cankers and epicormic branching, were most pronounced at extreme ends of the gradient. Periodic diameter increments decreased for suppressed trees but increased for dominant trees from north to south, primarily related to climatic factors. Variation in annual diameter increments was strongly associated with moisture availability, with diameter growth being greatly reduced during episodic droughts at the more southerly sites. At one site that experienced both drought and defoliation in 1988, worsening crown condition, elevated mortality, and reduced growth were consistent with the effects of acute levels of environmental stress. While most northern hardwood forests in the Great Lakes region are currently healthy, our results provide additional evidence that these forests are sensitive to increased severity of environmental stress, and may experience alterations in mortality and growth if climate changes as some have predicted. Neil W. MacDonald