黄土丘陵区草地根系生物量对踩踏干扰生物结皮的响应

为明确干扰生物结皮对高等维管束植物的影响，本研究以黄土丘陵区退耕封禁20年左右的草地为对象，通过野外调查与室内分析相结合，研究了踩踏干扰对退耕地生物结皮及植物根系生物量的影响。结果表明：干扰降低了生物结皮盖度，增加了植物盖度；干扰显著增加植物根系总生物量，37%干扰度组较不干扰组增加104.55%，其中0~10 cm土层较不干扰组增加204.59%；干扰增加了0~10 cm土壤含水量，48%干扰度组较不干扰组增加22.37%；干扰生物结皮降低了夏季午后土壤温度，37%干扰度组较不干扰组降低5.85℃；干扰增加了生物结皮下层土壤全氮含量，影响了土壤养分循环以及水文、温度的重新分配，促进了与之镶嵌分布的植物根系的生长，并促使草地根系浅层化。

Effects of Simulated Sheep Trampling on Biological Soil Rrusts and Plant Root Biomass on the Grassland of the Loess Plateau in China

This study was aimed to study the effects of simulated sheep trampling on biological soil crusts and plant root biomass on the grassland in the loess plateau,which had been prohibited grazing for 20 years,through the field investigation and lab analysis. The results showed that the disturbance decreased the coverage of biological soil crusts,increased the coverage of plants and the total root biomass. The 37% disturbance intensity increased the total root biomass by 104.55%. And the total root biomass in 0~10 cm soil layer was increased by 204.59%. With the increase of disturbance intensity,the soil water content in 0~10 cm soil layer increased gradually. The 48% disturbance intensity increased the soil water content by 22.37%and promoted the accumulation of root biomass. The 37% disturbance intensity decreased the soil temperature by 5.85℃. The disturbance increased the total soil nitrogen content in the subsoil of biological soil crusts,affected the soil nutrient cycle and the redistribution of hydrology and temperature. The disturbance promoted the growth of plant roots,meanwhile induced the shallowness of the root system architecture.