PARENT SESSION
Oral Session #42: Decomposition.
Presiding: K. Gross
Tuesday, August 6. 1:00 PM to 4:45 PM. Apache Meeting Room, TCC.
The detritivores of semi-arid African savannas: Community effects on decomposition.
Schuurman, Gregor*,1, 1 University of Washington, Seattle, WA
ABSTRACT- Understanding how communities contribute to biogeochemical processes is difficult because in most ecosystems decomposition is mediated by complex mesofaunal and microbial communities. Functional redundancy in decomposer communities is therefore difficult to study. In contrast to most ecosystems, decomposition in semi-arid Africa is dominated by a small number of termite species of the fungus-growing subfamily Macrotermitinae. I studied community composition and decompostion rates in northern Botswana, in order to determine whether the Macrotermitine species were functionally redundant. I established 20 research plots, using standard methodology of toilet rolls baits to assess community composition and pre-weighed, labeled, pieces of wood to assess decomposition rates. Rolls were checked weekly. Wood samples were collected and weighed after the three months at the end of the wet season, and then new pieces were deployed for three subsequent dry season months. Most plots contained several of the five regional Macrotermitine species, as well as some non fungus-growers, but relative abundances of termite species differed among plots. Stepwise regression analysis produced a model that included abundances of only two species, Macrotermes michaelseni and Microtermes sp. (both Macrotermitines), to explain differences in decomposition rates among plots in the wet season. In the dry season Microtermes sp. feeding activity declined substantially and only M. michaelseni was included in the model. These results show that only two of the Macrotermitine species stand out as being important to decomposition, but that these two differ markedly in terms of seasonal activity patterns. Coupled with evidence that land use and global climate change may affect Macrotermes and Microtermes differently, the lack of functional redundancy suggests that decomposition in these systems might be sensitive to human impacts, with important consequences for regional carbon and nutrient cycling.
KEY WORDS: Decomposition, termites, redundancy, Africa