Megan Watters

The effects of grazing by large herbivores on carbon and nitrogen dynamics in montane grasslands of Jasper National Park

To quantify the effects of grazing on vegetation and soils in the montane grasslands of Jasper National Park, I conducted a series of vegetation and soil surveys at 9 grassland sites in 2001-2002. Since 1946, grassland vegetation cover has not improved as much as expected given reduced ungulate numbers and improved precipitation, possibly due to grassland succession to forest. Although plant cover, carbon and nitrogen inputs, and species composition were affected by past grazing regimes, belowground variables including root biomass, microbial biomass and activity, soil N and soil moisture, did not differ from undefoliated plots after 2 year of seasonal clipping or by past grazing. Soil type, however, had a strong effect on belowground variables, with lower root biomass, microbial biomass, soil moisture and mineral N on sandy soils than loamy soils. I suggest that future research focus on the effects of grassland management and exploring various soil nutrient indicators.