Differential responses of soil cellulase enzymes and oxidative enzymes to soil erosion

Abstract

The activities of soil carbon-degrading enzymes play an important role in determining carbon mineralization. Soil erosion is the most common form of soil degradation worldwide, but the responses of cellulase enzymes and oxidative enzymes to erosion remain elusive. Here, we studied the effects of erosion on β-1,4-Glucosidase (BG) and phenol oxidase (PHO) activities as well as their contributions to carbon mineralization at three erosion hotspots in China. We found that erosion did not change SOC-normalized BG activity in both eroded plots and depositional plots, but significantly increased SOC-normalized PHO activity in eroded plots. The SOC-normalized PHO activity explained more variance in carbon mineralization than BG. Further analysis showed that the lignocellulose index (the ratio of PHO to the sum of BG and PHO) was closely related to microbial stoichiometric balance rather than the carbon composition under the impact of erosion. These results indicate that erosion may stimulate the utilization of recalcitrant carbon by microbial oxidase in eroded areas, potentially exacerbating the loss of soil carbon in slopes.