BARBARA BLEHO - Graduate Student, NRI, University of Manitoba
Grazing exclusion at Grasslands National Park has resulted in an increasingly homogenized plant community, which in turn has had an effect on local wildlife. My research investigates the effects of prescribed grazing at various intensities on mixed-grass prairie songbirds. Some topics I plan to investigate include (1) differences in songbird densities between grazed and ungrazed low-lying and riparian areas where vegetation is of poor forage value, (2) within-pasture differences in songbird densities and possible links to grazing patterns, and (3) relationships between songbird densities and plant species distribution. Research will be conducted following a two phase, modified Before-After-Control-Impact (Beyond BACI) design. Nine pastures have been established in the East Block of GNPC. Four conventionally grazed pastures in the adjacent ranch lands serve as temporal controls. Ten point count plots and ten vegetation sampling plots have been set up in each pasture, totaling 130 plots of each. In Phase 1 (2006 and 2007), three rounds of point counts were conducted from late May to June. Plant species diversity, percent cover, litter cover, and vegetation height were recorded in June and July. In Phase 2 (2008), cattle will be introduced into six park pastures at various grazing intensities. Three park pastures will be left as ungrazed spatial controls. Data will be collected as in Phase 1. Data from the three years will be evaluated using generalized linear mixed-effects models. The results of this study will be important in establishing suitable habitat for species at risk and appropriate grazing intensities for maximum species diversity within GNPC.