Articles | Volume 2, issue 1
SOIL, 2, 101–110, 2016
SOIL, 2, 101–110, 2016

Original research article 09 Mar 2016

Original research article | 09 Mar 2016

Soil microbial communities following bush removal in a Namibian savanna

Jeffrey S. Buyer1, Anne Schmidt-Küntzel2, Matti Nghikembua2, Jude E. Maul1, and Laurie Marker2 Jeffrey S. Buyer et al.
  • 1USDA, ARS, BARC, Sustainable Agricultural Systems Laboratory, Beltsville, MD, USA
  • 2Cheetah Conservation Fund, Otjiwarongo, Namibia

Abstract. Savanna ecosystems are subject to desertification and bush encroachment, which reduce the carrying capacity for wildlife and livestock. Bush thinning is a management approach that can, at least temporarily, restore grasslands and raise the grazing value of the land. In this study we examined the soil microbial communities under bush and grass in Namibia. We analyzed the soil through a chronosequence where bush was thinned at 9, 5, or 3 years before sampling. Soil microbial biomass, the biomass of specific taxonomic groups, and overall microbial community structure was determined by phospholipid fatty acid analysis, while the community structure of Bacteria, Archaea, and fungi was determined by multiplex terminal restriction fragment length polymorphism analysis. Soil under bush had higher pH, C, N, and microbial biomass than under grass, and the microbial community structure was also altered under bush compared to grass. A major disturbance to the ecosystem, bush thinning, resulted in an altered microbial community structure compared to control plots, but the magnitude of this perturbation gradually declined with time. Community structure was primarily driven by pH, C, and N, while vegetation type, bush thinning, and time since bush thinning were of secondary importance.

Short summary
Savannas represent most of the world’s livestock grazing land and are suffering worldwide from bush encroachment and desertification. We studied soil under bush and grass in a bush-encroached savanna in Namibia. With bush removal, there were significant changes in soil chemistry and microbial community structure, but these changes gradually diminished with time. Our results indicate that the ecosystem can substantially recover over a time period of approximately 10 years following bush removal.