In rangeland ecosystems, plant litter decomposition supports plant productivity and soil fertility through carbon (C) and nutrient cycling and moisture conservation. Previous studies in rangeland ecosystems suggest that grazing can affect decomposition rates, and therefore, have important impact on biogeochemical cycles. To better understand this relationship, including the specific impact of grazing on shifts in plant species composition, we initiated a two-year study at 15 sites with paired (grazed and non-grazed) plots within four natural subregions including Dry Mixedgrass, Mixedgrass, Foothills Fescue and Central Parkland in Alberta, Canada. We are measuring litter decomposition rates of nine litter types, including four grazing-tolerant ‘increasers' and three grazing-susceptible ‘decreaser' species, a local community litter mix and cellulose paper as a standard, in grazed and non-grazed rangeland. We will present our first six-month of data to test the following hypotheses: Decomposition rates across natural subregions will be strongly controlled by climate due to differences in precipitation and temperature among regions. We expect litter will decompose more rapidly in warmer and wetter regions due to higher microbial activity, In general, ‘increasers' will decompose more rapidly than ‘decreaser', because these rapidly growing species tend to have less complex chemical structure that is more easily decomposable, Decomposition rates will be higher under the grazing treatment due to enhanced biological activity. Ultimately, we aim to understand the effects of grazing and associated changes in the plant community on decomposition rates and subsequent C storage across a range of natural subregions. This study will detail how changes in decomposition occur in plant communities due to grazing, and how subsequent changes in microbial activity may alter decomposition rates, and potentially reveal mechanisms through which management can improve C storage, soil fertility and plant productivity in rangelands.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.