中国科学院水利部水土保持研究所机构知识库

Soil C-acquiring enzymes are good indicators for the biological mechanism of soil nutrients and organic matter cycles. However, they have been used less frequently to assess the ecological stability and soil C cycle in eroding landscapes due to a lack of knowledge of the responses of C-acquiring enzyme activities to soil erosion and deposition. In the present study, a 3-year field simulation experiment was conducted to examine the variations in the activities of C-acquiring enzymes (β-1,4-xylosidase (βX), β-1,4-glucosidase (βG) and β-D-cellobiohydrolase (CBH)) from erosion-deposition plots with different slope gradients (5^◦, 10^◦ and 20^◦) on the Loess Plateau in China (2016–2018). The activities of βX, βG and CBH were higher in the depositional plots than in the erosional plots, and those differences were enlarged with increasing slope gradients. Compared to the 5^◦-erosional plot, the activities of βX, βG and CBH respectively declined by 3.2–4.5%, 14.3–37.5% and 12.7–29.1% in the 10^◦-and 20^◦- erosional plots. The βX, βG and CBH activities were 2.2–18.1%, 17.3–32.1% and 14.8–86.2% higher in the 10^◦- and 20^◦-depositional plots than in the 5^◦-depositional plot. Moreover, the total soil CO₂ emissions from the whole erosion-deposition plots decreased as slopes steepened. The displaced runoff and sediment depleted soil moisture, SOC, clay and microbial biomass in the erosional plots but enhanced these resources in the depositional plots, which can account for the changes in C-acquiring enzyme activities. The spatial distribution of enzyme activities affected soil CO₂ emissions in a positive linear function. The sensitive responses of the C-acquiring enzyme activities and the controlling effects of C-acquiring enzyme activities on soil CO₂ emissions during erosion and deposition processes, should be properly considered in assessing the biological mechanism for nutrition cycling in regions predominated with fragmented eroding landscapes.