Climatic stress-induced changes in plant chemistry alter the compound-specific degradation of litter during decomposition

Plant litter decomposition supports ecosystem productivity and influences soil carbon cycling. Drought directly impacts decomposition by decreasing soil moisture and indirectly by altering plant tissue chemistry, an aspect that is less explored in decomposition research.

To elucidate the above interactive effects of altered precipitation on litter decomposition, we conducted an in situ and reciprocal decomposition experiment at a climate manipulation experiment (BACE) in MA, USA, using litter from Quercus rubra and Quercus velutina exposed to ambient, dry, and wet precipitation treatments for four years at BACE.

Plant tissues exposed to dry litter origin treatment were enriched in alkyl compounds and lignin in both species. Litter of Q. rubra from the dry treatment initially decomposed faster in the dry (38%) than in the wet treatment (28%). Similarly, litter of Q. rubra from the wet treatment initially decomposed faster in the wet (40%) compared to the dry (25%) treatment. Interestingly, litter of both species from the dry treatment, when decomposed in dry, ambient, and wet treatments, had more alkyl compounds, representing a legacy effect of the drought-induced altered initial litter chemistry that persisted throughout the two years of decomposition.

Our study provides novel insights that drought stress-induced changes in litter chemistry can influence mass loss and create a legacy effect on the persistence of recalcitrant compounds during decomposition.