Effects of fencing and grazing on the biomass of typical steppe in the Loess Plateau

The excavating block and harvesting methods were used to investigate the effect of grazing and fencing on aboveground and belowground biomass of typical steppe in the Loess Plateau.This study indicated that the fencing significantly increased the cover,height,aboveground and belowground biomass of steppe community when compared to grazing.The vertical distribution of belowground biomass was a inverted typical pyramid or T-shape,indicating that the belowground biomass declined in the grazing and fencing areas with the increase of soil depth,which could be simulated by the exponential function.The belowground biomass at 0～10 cm soil layer was significantly bigger than that at 20～30,30～40,40～50 cm soil layer(P0.01) for grazing and fencing areas,and the belowground biomass at 0～50 cm soil layers in the fencing area was higher than that in the grazing area.The ratio of the belowground to aboveground biomass was relatively large because of the local arid climatic condition,and the ratio of the belowground to aboveground biomass in the fencing areas was greater than that in the grazing areas due to different soil contents.