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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #309193
Title: Soil microbial communities following bush removal in a Namibian savanna

Author
item Buyer, Jeffrey
item SCHMIDT-KUNTZEL, ANNE - Cheetah Conservation Fund
item NGHIKEMBUA, MATTI - Cheetah Conservation Fund
item Maul, Jude
item MARKER, LAURIE - Cheetah Conservation Fund

Submitted to: Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2016
Publication Date: 3/9/2016
Publication URL: http://handle.nal.usda.gov/10113/62000
Citation: Buyer, J.S., Schmidt-Kuntzel, A., Nghikembua, M., Maul, J.E., Marker, L. 2016. Soil microbial communities following bush removal in a Namibian savanna. Soil. 2:101-110.

Interpretive Summary: Savannas, which are defined as mixed ecosystems of woody plants and grasses, represent most of the world’s livestock grazing land. Savannas worldwide are suffering from bush encroachment and desertification which reduce the carrying capacity of the land for livestock and wildlife. We studied soil microbial communities under bush and grass in a savanna suffering from bush encroachment in Namibia. Bush was removed from plots in 2003/4, 2007, and 2009. Soil samples were taken in 2012 and 2013, 3 to 10 years after bush removal. We found that soil pH, carbon, nitrogen, and microbial biomass were consistently higher under bush than grass. Soil microbial community structure was also significantly altered by the vegetation type. 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 soil ecosystem is altered by bush encroachment, and with bush removal the ecosystem can substantially recover over a time period of approximately 10 years. These results will be useful to ecologists planning and monitoring restoration of bush-encroached savannas.

Technical Abstract: Savanna ecosystems are subject to desertification and bush encroachment, which reduce the grazing value of the land and hence the carrying capacity for wildlife and livestock. In this study we examined the soil microbial communities under bush and grass in Namibia. We analyzed the soil at a chronosequence of sites where bush was removed at 3-9 years before sampling. Soil microbial biomass and the biomass of specific taxonomic groups was determined by phospholipid fatty acid (PLFA) analysis while the community structure of Bacteria, Archaea, and fungi was determined by multiplex terminal restriction fragment length polymorphism (TRFLP) 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. Bush removal resulted in an altered microbial community structure compared to control plots, but the magnitude of this perturbation gradually reduced with time. Community structure was primarily driven by pH, C, and N, while vegetation type, bush removal, and time since bush removal were of secondary importance.