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. Climate could directly affect decomposition by altering reaction rates which is well researched. However, climate could indirectly affect litter decomposition by modulating the chemistry of plant tissues in their formative stages, a factor which is often overlooked in litter decomposition studies. 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%). 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 harvested after one year and two years of decomposition and subjected to mass loss, extracellular enzyme assays and chemical characterization.
Results/Conclusions
Litter that was formed under dry-precipitation treatment was enriched in alkyl compounds and lignin. After two years of decomposition, the litters of both species lost ~60% of the original mass. The mass loss of Q. rubra varied by an interaction of precipitation and origin of litter. The litter from dry treatment had higher mass loss 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. The microbial peroxidase activity was mainly influenced by the identity of the litter and to a lesser extent by the climate in which the litter decomposed. In Q. velutina the mass loss varied only by precipitation treatments where the litter decomposed in the dry treatment had the lowest mass loss than the ambient and wet treatments. In both species, the chemical composition of litter remained after two years of decomposition depended on the identity of the litter. The litter exposed to the dry treatment at their formative stages had higher alkyl compounds after two years of decomposition. Climatic influence on the chemistry of litter at its formative stages would dramatically alter litter decomposition parameters under future climates.