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Species diversity of arbuscular mycorrhizal fungi in tropical forest fragments and adjacent pastures.
Aldrich-Wolfe, Laura1, 1
ABSTRACT- Conversion of forest to pasture has been hypothesized to lead to declines in species richness and abundances of mycorrhizal fungi species. Evidence for such declines is currently incomplete. In this study, I compared species diversity of arbuscular mycorrhizal (AM) fungi for three pairs of forest fragment and adjacent pasture sites in a farming community in Coto Brus, southern Costa Rica. I determined species diversity of AM fungi by both direct assessment of field-collected soil samples and estimates from trap cultures in the greenhouse. Results to date suggest conversion of forest to pasture produces shifts in abundances of many AM fungi species rather than general declines. Species richness of AM fungi was higher in pasture than forest sites, despite the depauperate nature of the pasture plant community relative to that of forest. Overall abundance of AM fungi was similar between pasture and forest. While some AM fungi species were common in both forest and pasture sites, others were abundant in one vegetation type and rare or absent in the other. These results suggest pasture plants support a AM fungi community that may be at least as species-rich as that of forested sites, but that differs markedly in its composition. Consequences of this shift for forest regeneration need to be examined.
KEY WORDS: arbuscular mycorrhizal fungi, tropical forest, pasture, fungal diversity