The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Tuesday, January 29, 2008
6
Landscape influences on soil moisture within a rough fescue grassland of the Alberta Parkland
Eliza S. Deutsch and Edward W. Bork. Agricultural, Food and Nutritional Science, University of Alberta, 410E Agriculture/Forestry Center, Edmonton, AB T6G 2P5, Canada
Landscapes of the Aspen Parkland in Western Canada are highly complex environments characterized by variable topography and strong gradients of moisture availability. Plant litter can influence soil moisture in this region through reduced evaporative losses and altered soil infiltration. The objective of this study was to determine the relative contribution of litter in influencing soil moisture after rainfall at the landscape scale. Thirty plots were set up across a catena toposequence within rough fescue grasslands and monitored monthly during the summer of 2007 to quantify the influence of litter, plant community composition, soils, topography, and weather variables on soil moisture content. Litter levels were modified on one-thirds of the plots at the beginning of the growing season to ensure variable litter loads across the landscape. In-situ moisture readings were taken with a TDR probe for five consecutive days after major rainfall events in each of May, June, July and August in order to generate soil drying curves. Litter and plant community parameters were quantified through biomass and cover measurements. Soils were assessed by determining organic matter, texture, and depth of the Ah layer, along with lab determination of key hydrologic characteristics including soil field capacity and permanent wilting point. Topography was quantified by measuring slope, aspect and position (high, middle and low slope). Weather data was obtained from a local weather station. Initial results indicate litter influences on soil moisture were greatest during the first two days after rainfall. Structural equation modeling will ultimately be used to model the individual and cumulative influences of topographic, soil and vegetational influences, including litter, on soil moisture.