牧压梯度对克氏针茅生长和繁殖的影响

用比较样地法调查了牧压梯度对克氏针茅生长和繁殖的影响，结果表明：长期过度放牧使克氏针茅株丛发生破碎和小型化，营养生长的株丛密度增加，生殖生长的株丛密度减少，生殖枝比例下降，枝条生物量和种子产量下降，分蘖节向地表移动，株丛茎基部和根系的储藏碳水化合物含量显著减少。而中度放牧干扰使克氏针茅的株丛大小和生殖枝营养枝比例保持适中，有利于发挥株丛和枝条各自的生长和繁殖潜力。

Growth and reproduction of Stipa Krylovii population on a grazing gradient

The growth and reproduction of Stipa krylovii on a grazing gradient,that is,no grazing(NG),light grazing(LG),moderate grazing(MG),and heavy grazing(HG),were studied in 1995 on a tylical steppe dominated by Stipa krylovii .This research was carried out on a series of comparative sampling plots along with a spatial gradient of grazing.The results showed that over grazing for years was always associated with tussock fragmentation,size miniatwing,the process of tillering nodes going up near to the soil surface and declining of carbohydrate reserves(soluble,sugar,reducing sugar,fructose,and sucrose)in the stem base and roots.On the contrary moderate grazing was always led to a rational self control on the size,the ratio of vegetative and reproductive tillers.