封育和放牧对黄土高原典型草原生物量的影响

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

采用收割法和土柱法研究封育和放牧两种方式对黄土高原典型草原地上、地下生物量的影响。结果表明,1）与放牧区相比,封育显著提高了草原植被的盖度和高度,增加了生物量（地上和地下）。2）封育区与放牧区草地地下生物量的垂直分布均呈典型的倒金字塔型或T字形的锯齿状分布。地下生物量都随土层深度增加而降低、符合指数函数减小规律。3）地下各层生物量变化幅度很大,其中0~10 cm土层与20~30、30~40、40~50 cm土层差异达到极显著（P〈0.01）,与放牧区相比,封育区在0~50 cm各层的地下生物量都高于放牧区。4）地下生物量/地上生物量的值偏大,与当地干旱的气候有关。由于水分条件的不同,封育区地下生物量/地上生物量的值大于放牧区。

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.