Ruan, H.H., Zou, X.M., Scatena, F.N., Zimmerman, J.K., 2004.
Asynchronous fluctuation of soil microbial biomass and plant litterfall
in a tropical wet forest. Plant and Soil 260, 147–154.
Carbon availability often controls soil microbial growth and there is evidence that at regional scales soil microbial
biomass is positively correlated with aboveground forest litter input. We examined the influence of plant litterfall
on annual variation of soil microbial biomass in control and litter-excluded plots in a tropical wet forest of Puerto
Rico. We also measured soil moisture, soil temperature, and plant litterfall in these treatment plots. Aboveground
plant litter input had no effect on soil microbial biomass or on its pattern of fluctuation. Monthly changes in
soil microbial biomass were not synchronized with aboveground litter inputs, but rather preceeded litterfall by one
month. Soil microbial biomass did not correlate with soil temperature, moisture, or rainfall. Our results suggest that
changes in soil microbial biomass are not directly regulated by soil temperature, moisture, or aboveground litter
input at local scales within a tropical wet forest, and there were asynchronous fluctuation between soil microbial
biomass and plant litterfall. Potential mechanisms for this asynchronous fluctuation include soil microbial biomass
regulation by competition for soil nutrients between microorganisms and plants, and regulation by below-ground
carbon inputs associated with the annual solar and drying-rewetting cycles in tropical wet forests.