Bomas (livestock corrals) create hotspots (or glades) within tropical savanna or grassland matrices and can be used to rehabilitate degraded rangeland. High soil and foliar nutrient content within the site are maintained by feedback mechanisms – notably, increased use by wild herbivores. The duration of boma occupancy varies and more frequent relocation (shorter occupancy) could increase the area rehabilitated per unit time. However, little is known about the minimum – or threshold – occupancy duration necessary to establish the feedbacks that maintain hotspots/glades. This study consisted of five replicates of five treatments: bomas occupied for 0 (control), 4, 7, 14 and 28 days. Vegetation and animal dung (a proxy of use) were monitored at several time points. The threshold for graminoid and total herbaceous cover appeared to be crossed by all treatments >0 days. But the 4-day treatment did not show a significantly lower percentage of either short-lived grass cover or species richness (indicators of glades) than the control. Use by wild herbivores in the 14- and 28-day treatments was significantly higher than in the control, but the 4- and 7-day treatments were not. These results show that the thresholds are dependent on the focal variable. Although bomas occupied for shorter periods reduce bare ground and increase herbaceous cover effectively, they may not attract enough herbivores to instigate feedbacks required to maintain the elevated soil and foliar nutrient contents characteristic of glades over longer time periods. These findings also emphasize the importance of monitoring multiple variables for assessing restoration success.
Audio/Video, Conference Presentation, SER2019
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Society for Ecological Restoration