New Publication in Ecology Letters by B Bestelmeyer
A test of critical thresholds and their indicators in a desertification-prone ecosystem: More resilience than we thought. Read the publication http://jornada.nmsu.edu/bibliography/13-005.pdf
Abstract: Theoretical models predict that drylands can cross critical thresholds, but experimental manipulations to evaluate them are non-existent. We used a long-term (13-year) pulse-perturbation experiment featuring heavy grazing and shrub removal to determine if critical thresholds and their determinants can be demonstrated in Chihuahuan Desert grasslands. We asked if cover values or patch-size metrics could predict vegetation recovery, supporting their use as early-warning indicators. We found that season of grazing, but not the presence of competing shrubs, mediated the severity of grazing impacts on dominant grasses. Recovery occurred at the same rate irrespective of grazing history, suggesting that critical thresholds were not crossed, even at low cover levels. Grass cover, but not patch size metrics, predicted variation in recovery rates. Some transition-prone ecosystems are surprisingly resilient; management of grazing impacts and simple cover measurements can be used to avert undesired transitions and initiate restoration. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Bestelmeyer, B.T.a, Duniway, M.C.ab, James, D.K.a, Burkett, L.M.a, Havstad, K.M.a
a USDA-ARS Jornada Experimental Range and Jornada Basin LTER, Box 30003, MSC 3JER, New Mexico State University, Las Cruces, NM 88003 USA; b U.S. Geological Survey Southwest Biological Science Center, 2290 SW Resource Blvd, Moab, UT 84532 USA