The Effects of Soil Bacterial Community Structure on Decomposition in a Tropical Rain Forest

Jonathan W. Leff, Diana R. Nemergut, A. Stuart Grandy, Sean P. O'Neill, Kyle Wickings, Alan R. Townsend, Cory C. Cleveland

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Soil microorganisms are key drivers of terrestrial biogeochemical cycles, yet it is still unclear how variations in soil microbial community composition influence many ecosystem processes. We investigated how shifts in bacterial community composition and diversity resulting from differences in carbon (C) availability affect organic matter decomposition by conducting an in situ litter manipulation experiment in a tropical rain forest in Costa Rica. We used bar-coded pyrosequencing to characterize soil bacterial community composition in litter manipulation plots and performed a series of laboratory incubations to test the potential functional significance of community shifts on organic matter decomposition. Despite clear effects of the litter manipulation on soil bacterial community composition, the treatments had mixed effects on microbial community function. Distinct communities varied in their ability to decompose a wide range of C compounds, and functional differences were related to both the relative abundance of the two most abundant bacterial sub-phyla (Acidobacteria and Alphaproteobacteria) and to variations in bacterial alpha-diversity. However, distinct communities did not differ in their ability to decompose native dissolved organic matter (DOM) substrates that varied in quality and quantity. Our results show that although resource-driven shifts in soil bacterial community composition have the potential to influence decomposition of specific C substrates, those differences may not translate to differences in DOM decomposition rates in situ. Taken together, our results suggest that soil bacterial communities may be either functionally dissimilar or equivalent during decomposition depending on the nature of the organic matter being decomposed.

    Original languageEnglish
    Pages (from-to)284-298
    Number of pages15
    JournalEcosystems
    Volume15
    Issue number2
    DOIs
    StatePublished - Mar 2012

    Keywords

    • bacterial diversity
    • carbon cycle
    • decomposition
    • ecosystem function
    • lowland tropical rain forest
    • microbial community composition
    • organic matter
    • pyrosequencing
    • soil microbiology
    • soil respiration

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