Generation of ecosystem hotspots using short-term cattle corrals in an African savanna

Authors: Porensky, Lauren; VEBLEN, KARI - Utah State University

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2015
Publication Date: 4/10/2015
Publication URL: http://handle.nal.usda.gov/10113/60980
Citation: Porensky, L.M., Veblen, K.E. 2015. Generation of ecosystem hotspots using short-term cattle corrals in an African savanna. Rangeland Ecology and Management. 68:131-141.

Interpretive Summary: Many rangelands are now being managed for multiple uses, and it is important to identify livestock management practices that maximize rangeland productivity, biodiversity and wildlife conservation. In sub-Saharan Africa, pastoralists and ranchers use temporary thorn-fence corrals (“bomas”) to protect livestock at night. Traditional bomas (used for months or years, then abandoned) develop into ecosystem hotspots (“glades”) that attract diverse wildlife and persist for decades or even centuries. In central Kenya, livestock managers have recently begun using metal-fenced “mobile bomas” which are moved after only days or weeks. It is unclear whether short-term mobile boma sites will also develop into valuable glade hotspots. We evaluated the effects of mobile bomas (used for one month) on soils, forage quality, grasses, woody plants, and wildlife. After 18 months, nutrient concentrations in soils and forage were higher in experimental glades (abandoned boma sites) than at paired reference sites. Plant communities inside experimental glades became dominated by a palatable, rhizomatous grass species, Cynodon plectostachyus. After 32 months, wildlife use and wildlife diversity were higher in experimental glades than at paired reference sites. By concentrating livestock during the night in short-term corrals, managers can create hotspots that attract wildlife and provide palatable forage for livestock.

Technical Abstract: Many rangelands are now being managed for multiple uses, and it is increasingly important to identify livestock management practices that maximize long-term productivity, biodiversity and wildlife conservation. In sub-Saharan Africa, pastoralists and ranchers use temporary thorn-fence corrals (“bomas”) to protect livestock at night. Traditional bomas (used for months or years, then abandoned) develop into productive nutrient hotspots that attract diverse wildlife and persist for decades or even centuries. In central Kenya, livestock managers have recently begun using metal-fenced “mobile bomas” which are moved after only days or weeks. Although the assumption is that these will develop into ecosystem hotspots (“glades”) similar to those created by traditional bomas, whether this is true or not remains unclear. We used a broad-scale manipulative experiment to evaluate the ecosystem-level effects of mobile boma sites used for one month. We also investigated impacts of initial boma density on glade development. We randomly assigned 12 sites to one of three density treatments: one boma, two bomas 200 m apart, or two bomas 100 m apart. Before boma establishment and at 1, 6, 12, 18 and 32 months after abandonment, we sampled soil nutrients, foliar nutrients, plant communities and wildlife use (via dung counts) within these experimental glades and at paired reference plots (200 m away). By 18 months, surface soil nutrient concentrations in experimental glades were similar to those in traditionally-formed glades. Glade plant communities became dominated by a palatable, rhizomatous grass species, Cynodon plectostachyus. After 32 months, wildlife use by browsing and mixed feeding ungulates was 9 times higher in experimental glades than at paired reference sites. Boma density had few impacts on within-glade development patterns. These results demonstrate that by concentrating livestock during the night in short-term corrals, managers can create hotspots that increase functional heterogeneity, attract wildlife, and provide palatable forage for livestock.