A test of critical thresholds and their indicators in a desertification-prone ecosystem: more resilience than we thought

TitleA test of critical thresholds and their indicators in a desertification-prone ecosystem: more resilience than we thought
Publication TypeJournal Article
Year of Publication2013
AuthorsBestelmeyer BT, Duni D, James D.K, Burkett LM, Havstad K
JournalEcology Letters
Volume16
Start Page339
Pagination339-345
Date Published01/2013
ARIS Log Number285842
Keywordsdesertification, early warning, grazing, long-term experiment, patch size, regime shift, resilience, state-transition model
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.

URL/files/bibliography/13-005.pdf
DOI10.1111/ele.12045