UVM Theses and Dissertations
Format:
Print
Author:
Williams, Kristin May
Dept./Program:
Plant and Soil Science
Year:
2013
Degree:
M.S.
Abstract:
Roadways have a potential number of ecological effects on adjacent soil communities via physical and chemical alteration of the roadside. Chemical alteration may include deposition of pollutants such as the accumulation of dust, gravel, litter, car exhaust depositions, and deicing materials. The objective of this study was to quantify effects of roads by traffic road type (highway, two-lane paved, and gravel) and distance from the road, on soil forest soil nematode communities, in conjunction with chemical and physical measures of soil quality. This research was located within two watersheds in the state of Vermont, where deicing salts are spread regularly on roads during winter months. Using GIS mapping, 10-12 transect starting points were selected randomly for each road type. Transects were constructed perpendicular to the road, with samples along each transect based upon roadside features at the following locations: shoulder, sideslope, ditch, backslope, and forest locations -10 m from forest edge, and 50m from road crown.
Standard soil property measures were significant (p [less than or equal to] 0.05) as interactions, particularly interactions between road type and distance and road type and topography. Many pollutants decreased with distance, the ditch was also an area of pollutant accumulation, and the forest edge appeared to be filtering pollutants from the interior forest. Road type with greatest pollutant accumulations depended on the pollutant in question. Salt concentrations were greatest by two-lane paved roads, while heavy metal concentrations were greatest by highway roads. Topography was an important feature of the roadside that needs further consideration. There were significant differences in all nematode community measures based upon distance as a main effect, as well as some interactions between distance, road type, and topography. Nematode indices indicated increased disturbance closer to the road particularly at the shoulder, later ecological succession status in the forest, and a difference between the forest and grassy road verge.
Greater values of the fungivores to bacterivores ratio (FB) in the forest suggested a shift in the decomposer foodweb. The distribution of nematodes among trophic groups proved to a useful indicator of micro-topography effects, in addition to measures of ecological sucession and genus diversity. Relative abundance of plant-parasites and algivores was greatest along the roadside (grassy areas and ditch, respectively), and omnivores and predators were relatively more abundant in the forest, as well as the ditch. Canonical Correspondence Analysis supported that gravel roads were associated with a less disturbed nematode community, as well as a shift in later succession in the nematode community with distance from the road. Roadside conditions are a complex of chemical and physical soil properties, vegetation, moisture, and other abiotic road conditions.
Standard soil property measures were significant (p [less than or equal to] 0.05) as interactions, particularly interactions between road type and distance and road type and topography. Many pollutants decreased with distance, the ditch was also an area of pollutant accumulation, and the forest edge appeared to be filtering pollutants from the interior forest. Road type with greatest pollutant accumulations depended on the pollutant in question. Salt concentrations were greatest by two-lane paved roads, while heavy metal concentrations were greatest by highway roads. Topography was an important feature of the roadside that needs further consideration. There were significant differences in all nematode community measures based upon distance as a main effect, as well as some interactions between distance, road type, and topography. Nematode indices indicated increased disturbance closer to the road particularly at the shoulder, later ecological succession status in the forest, and a difference between the forest and grassy road verge.
Greater values of the fungivores to bacterivores ratio (FB) in the forest suggested a shift in the decomposer foodweb. The distribution of nematodes among trophic groups proved to a useful indicator of micro-topography effects, in addition to measures of ecological sucession and genus diversity. Relative abundance of plant-parasites and algivores was greatest along the roadside (grassy areas and ditch, respectively), and omnivores and predators were relatively more abundant in the forest, as well as the ditch. Canonical Correspondence Analysis supported that gravel roads were associated with a less disturbed nematode community, as well as a shift in later succession in the nematode community with distance from the road. Roadside conditions are a complex of chemical and physical soil properties, vegetation, moisture, and other abiotic road conditions.