Litter chemistry and microbial community modulates the effect of climate on the decomposition of plant litter

Background/Question/Methods

Decomposition of plant litter not only sustains ecosystem productivity, but also modulates the storage of C in soil. Predicted changes in precipitation may alter litter decomposition rates that could potentially feedback to climate change. Climatic changes can alter decomposition rates indirectly through affecting plant tissue chemistry during its formative stage and directly by modulating microbial community composition and functional activity. To elucidate the above direct and indirect effect of climatic changes on litter decomposition we subjected seedlings of two temperate tree species-Quercus rubra and Quercus velutina to three different precipitation treatments (ambient, drought (-50%) and wet (+50%) at the Boston-Area Climate Experiment (BACE), in Massachusetts, USA. The senesced litters of both species collected from the three precipitation treatments were subjected to an in situ and reciprocal litter decomposition experiment in all precipitation treatments. The litter bags from each treatment were collected after a year of decomposition and subjected to mass loss, extracellular enzyme assays and detailed chemical characterization.

Results/Conclusions

After a year of decomposition litters of both species lost aproximately 45-50% of the original mass. In Q.rubra the mass loss varied by an interaction of precipitation and origin of litter. Litter that was formed under dry-precipitation treatment decomposed faster when placed in the dry-precipitation treatment (in situ) than when placed in the wet-precipitation treatment (reciprocal). Similarly litter of Q. rubra that was formed under wet treatment decomposed faster when placed in the wet treatment than in dry and ambient treatments. In Q.velutina we observed a similar marginal trend where litter formed under dry treatment decomposed faster under in situ than under reciprocal treatments. The main effect of precipitation significantly affected mass loss of  Q.velutina, where the litter decomposed in the dry treatment had the lowest mass loss than the ambient and wet treatments. These responses were further analyzed in relation to the initial quality of litter, microbial community composition and extracellular enzyme activities. Our results highlight the complex interaction of climate induced changes in tissue chemistry and microbial community on the decomposition of plant litter.