中文摘要：

通过设置不同放牧处理（羊单牧、牛单牧、牛羊混合放牧和不放牧）,研究土壤氮素和优势种克氏针茅根系构型对不同放牧方式的响应。结果表明：放牧14个月后（约2个生长季）,牛单牧和牛羊混合放牧显著提高了10-20 cm土层土壤全氮含量,其中牛单牧提高了硝态氮含量,而牛羊混合放牧则以提高有机氮为主;不放牧区的克氏针茅地上生物量显著高于羊单牧、牛单牧和混合放牧区,而地下生物量差异不显著;在放牧处理14个月后,克氏针茅6项根系构型参数5项没有差异,但根系径级分级显示,不放牧区根系直径为2.5-3.5及4.0-4.5 mm的根系长度、体积和表面积显著高于其他放牧区。整体上看,放牧处理14个月,土壤和优势种植物的根系构型参数变化尚不明显,有待于继续观测。

英文摘要：

An experiment was conducted to investigate the effects of grazing treatments（ sheep or cattle grazing,mixed grazing of cattle and sheep,and no grazing） on root architecture of Stipa krylovii in the desert steppe of Inner Mongolia. After grazing for 14 months（ two growing seasons）,cattle grazing and mixed grazing of cattle and sheep significantly increased nitrogen content of soil at 10-20 cm depth. Cattle grazing improved nitrate content,while the mixed grazing of cattle and sheep mainly improved organic nitrogen content. The aboveground biomass in no grazing area was significantly greater than that in each grazing area,while belowground biomass was insignificantly different among the treatments. After grazing for 14 months,5 of 6 root architecture parameters of S. krylovii showed no differences among all the treatments. The classification of root diameter showed that root length,volume and surface area in diameter of 4.0-4.5 mm and2.5-3.5 mm in no grazing area were significantly greater than those of the grazing areas. Overall,14 months might be too short to change the soil and root architecture of the dominant plant,which deserves further observation.