Effect of clipping on aboveground biomass and nutrients varies with slope position but not with slope aspect in a hilly semiarid restored grassland

摘要

Clipping is a common management option in semiarid grasslands, but whether topography mediates the effects of clipping on plant and soil nutrients is poorly studied. We examined the interacting effects of clipping and topography (slope aspect and slope position) on the aboveground biomass and carbon (C) and nutrient concentration of graminoid and forb, as well as on soil organic carbon (OC) and nutrient content in a restored grassland under long-term grazing exclusion. Clipping increased the aboveground biomass of forb and total community, and decreased most C and nutrient concentration in aboveground biomass, but did not influence the aboveground biomass of graminoid or the content of soil OC and nutrient. Slope aspect did not change the effects of clipping on most plant aboveground biomass, or soil OC and nutrients. However, slope position altered the effects of clipping on soil inorganic nitrogen, total phosphorus, and available potassium, with lower nutrient levels on the upper slope but higher nutrient levels on the middle and lower slopes. The results demonstrate that slope position should be considered in predicting the response of soil biogeochemical processes to clipping in hilly semiarid restored grasslands.