PARENT SESSION
Oral Session #25: Soil Ecology: Microbial and Invertebrate. Presiding: W. Parsons.
Tuesday, August 7, 2001. 8:00 AM to 12:00 PM. Hall of Ideas G.
The effect of plant community composition on soil microbial community composition.
Carney, Karen1, Matson, Pamela1, Bohannan, Brendan1, Ewel, John2, 1 2
ABSTRACT- Little is known about whether plant diversity and/or compositional changes influence the composition of soil microbial communities. We characterized soil microbial communities in a controlled experiment in La Selva, Costa Rica that manipulated forest community composition while holding other environmental variables constant. Comparisons were made along a diversity gradient (plots contained 1, 3, 5, and >25 plant spp) and across plots that contained the same number of plants, but varied in plant species composition (1 or 3 species). We also characterized soil microbial communities in different types of land-use, including forest, abandoned cocao plantation, and pasture. Soil microbial communities were characterized using phospholipid fatty acids (PLFA) and terminal restriction fragment length polymorphisms (T-RFLP). Within the controlled experiment, plant community composition did not substantially affect soil pH or nutrient availability, but preliminary analyses indicate that it did influence microbial community composition. Principal components analyses of marker fatty acids revealed a separation of soil microbial communities from the >25 spp plot from those in plots with 1, 3, or 5 tree species; the latter three treatments were indistinguishable. Land-use altered microbial communities, the pasture community being distinct from the forest and cocao plots; no differences between forest and cocao plantation were detected. Anthropogenic modification of plant communities can affect microbial community composition; future studies should examine whether such changes lead to changes in the critical processes microbes perform.
KEY WORDS: microbes, plants, PLFA, T-RFLP