Global pattern and drivers of stable residue size from decomposing leaf litter

Stable residue from decomposing leaf litter is related to humus buildup in the forest floor and thus to the accumulation of carbon in the soil organic layer (OLC). However, the global pattern and controls of stable residue size remains poorly understood. Herein, the spatial pattern of stable residue size and its association with a series of potential drivers were evaluated by synthesizing available data worldwide. The results showed that stable residue size had a significant and positive correlation with the litter initial nitrogen (N) and lignin concentrations, and a negative correlation with the initial manganese concentration. Larger stable residues were found from decomposing broadleaf litter vs. coniferous litter. The decomposition of green leaf litter produces an equal amount of stable residue as that of brown litter. Stable residue size correlated quadratically with mean annual temperature and latitude, and linearly with mean annual precipitation. Methodological factor also matters, because stable residue size decreased as field incubation time increased. The boosted regression tree model indicated that litter initial traits have the most explanative ability for the variance in stable residue size. We highlighted that litter initial traits exert a predominant role over climate in shaping the stable residue size globally. Our findings are beneficial for a more accurate prediction of global-scale OLC accumulation.

Automated summary

Stable residue size in leaf litter decomposition is influenced by initial nitrogen, lignin, and manganese concentrations, as well as the type of litter and environmental factors such as temperature, latitude, and precipitation. The initial traits of litter have a stronger explanatory ability for the variance in stable residue size compared to climatic factors. These findings contribute to a better understanding and prediction of global-scale soil organic layer accumulation.