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.