Soil fauna show different degradation patterns of lignin and cellulose along an elevational gradient

The degradations of Cellulose and lignin from litter are crucial processes for carbon and nutrient cycling in forest ecosystems. However, the effects of soil fauna on these degradation processes are unclear despite their functional roles in litter fragmentation and microorganism regulation. Here we conducted a four-year field experiment using litterbags with two mesh sizes (3 and 0.04 mm) to assess the effects of soil fauna on cellulose and lignin degradation at four different elevations in southwestern China. Our results showed that the remaining masses of cellulose and lignin increased with elevation in the both meshed litterbags. Soil fauna decreased the remaining cellulose and lignin masses after 156-277 days of decomposition. At the end of the experiment, the stimulating effects of the soil fauna on the cellulose and lignin degradation were 11.7-34.2% and 14.2-32.7%, respectively, while soil fauna effects differed in magnitude on the degradations of lignin (higher) and cellulose (lower). The effects of soil fauna on lignin degradation significantly increased as the elevation decreased, regardless of the litter type; whereas soil fauna-derived cellulose degradation did not show the same pattern. The increases in temperature and/or fauna abundance promoted the effects of soil fauna on cellulose and lignin degradation, and these fauna effects were dependent to litter quality. These findings highlight that soil fauna promote cellulose and lignin degradation in different magnitude and these degradations are largely dependent on climate conditions and litter types.