Canopy Trimming Experiment (CTE) Microbial diversity DNA data

Hurricanes are common disturbances in the Caribbean region that affect tree distribution, species diversity and biomass in forests. Little is known of how microbial communities in soil and litter are affected by natural or anthropogenic disturbances. The objective of our study was to determine the relative abundance and diversity of microorganisms in leaf litter at different stages of decomposition, and the effect of canopy opening and debris addition or removal. Results: Leaf mass loss was slowest in the treatment with canopy trimming and debris removal. Canopy opening was associated with lower litter moisture, lower fungal connectivity between litter layers and slower mass loss after three months. Addition of green leaves increased moisture, and frequently accelerated mass loss of the senesced leaves below them at 17, 28 and 40.5, but not 53 weeks. After 28 weeks, mass loss showed a significant treatment interaction, and was concordant with fungal connectivity between litter cohorts. TRFLP profiles of the 16S rDNA digested with MnlI and fungal ITS digested with HaeIII shows that the microbial communities at 17, 28 and 53 weeks were highly divergent among treatments (Sorensen index of similarity). In comparisons of green versus senesced leaves within treatments, bacterial communities’ differed somewhat, fungal communities differed strongly, but mass loss did not differ. Conclusions: Microbial community changes through time can be related to microclimate and the availability of labile compounds. Fungi appeared to control the succession of microorganisms in decomposing leaves. Support for this work was provided by grants BSR-8811902, DEB-9411973, DEB-9705814 , DEB-0080538, DEB-0218039 , DEB-0620910 , DEB-1239764, DEB-1546686, and DEB-1831952 from the National Science Foundation to the University of Puerto Rico as part of the Luquillo Long-Term Ecological Research Program. Additional support provided by the University of Puerto Rico and the International Institute of Tropical Forestry, USDA Forest Service.