Termites, teabags and tropical savannahs

Change from wildlife to human-dominated land-uses can potentially alter the balance between microbial and soil fauna regulation of litter decomposition. Using the Tea Bag Index (TBI) we investigated the impact of land-use on microbial and termite decomposition in savannah ecosystems surrounding the Serengeti National Park, Tanzania. We buried over 1700 teabags across three land-uses (wildlife management, pasture and agricultural land) and a spatial and temporal climate gradient (wet and dry region and season) as well as permitting or excluding termite access to litter. Overall, we found that rooibos was strongly preferred by termites compared to green tea. Moreover, the contribution of termites to decomposition varied across land-uses with the highest mass loss in wildlife management areas followed by pasture and agricultural land. However, for green tea and rooibos excluding termites the trend reversed with higher decomposition rates in agricultural land, intermediate in pastureland and lowest in wildlife management areas. By modifying the TBI approach we demonstrated that the strength of the additive effect of termites on litter decomposition rates was dependent on litter type and land-use. Furthermore, greater human alteration of savannah land-uses is likely to lead to more microbial rather than termite-based litter decomposition with important implications for decomposition of recalcitrant litter types and nutrient cycling.