The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council.

Monday, January 28, 2008 - 3:40 PM

Brush Encroachment on Pasturelands in Western Canada

Marianne L. Schutz and David J. Walker. Environment and Geography, University of Manitoba, 467 Wallace Bldg, Winnipeg, MB R3T 2N2, Canada

Brush encroachment is a concern on pastures in the prairie provinces of Canada. Pastures provide grazing areas for livestock, but also represent some of the last remaining areas of grasslands for wildlife habitat. Therefore, increases in brush cover decrease the productivity of pasturelands for livestock and add to the decline of grassland habitats for wildlife. The objective of this study is to quantify the extent of brush encroachment during the last 50 years on pastures in the western Canada and look at potential mechanisms behind brush encroachment. Over two field seasons 67 pastures were visited; 32 publicly and 35 privately owned. The sites were randomly selected to be primarily in the Aspen Parkland Ecoregion and to represent various soil types and climatic conditions. There were two main components to this study. First aerial photos of all sites from three time periods (1946-59, 1970, 1994-2002), were digitized and the change in vegetation cover was assessed. Vegetation cover change varied considerably, with some sites experiencing significant changes in cover; increases and decreases of nearly 50% in brush cover. The second component was a vegetation and soil assessment. Two fields in each pasture were randomly selected; each field was stratified into grass, shrub and forest cover. In each stratum, vegetation cover and tree size class were noted and biomass and soil samples were taken. With respect to the soil samples pH, electrical conductivity (EC) and organic matter (OM) were measured. EC and OM tended to increase and pH to decrease from the grass strata in the forest strata. Management history was obtained from government agencies for the public sites and through a survey for the private lands. The management practices tended to be similar between the public and private lands, although the frequency of management tended to be higher on public lands.

 


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