甘南亚高山草甸人工草地的演替和质量变化

甘南亚高山草甸不同时间建立的垂穗披碱草（Ｅｌｙｍ ｕｓ ｎｕｔａｎｓ）人工草地植物群落结构和草地质量变化及其原因的研究结果表明： １． 垂穗披碱草人工草地只有在播种后第二年的产量最高，而草地质量指数ＩＧＱ （ｉｎｄｅｘ ｏｆｇｒａｓｓｌａｎｄ ｑｕａｌｉｔｙ）在七年生群落中最低； ２． 垂穗披碱草人工草地群落的种类数量和种多样性随年龄而增加，但其增加的模式各不相同； ３． 人工草地中垂穗披碱草地上部生物量的下降和草地质量指数的下降与土壤中速效磷含量的下降有关，而速效氮的含量对其影响不明显。因此，施磷可延长垂穗披碱草人工草地的使用寿命

SUCCESSION AND CHANGES OF GRASSLAND QUALITY OF THE ARTIFICIAL GRASSLAND COMMUNITIES IN SUBALPINE MEADOW IN GANNAN

The investigation dealt with the changes of the community structure as well as its cause of change, also with the quality of the artificial grassland sown with Elymus nutans at different time in the subalpine meadow in Gannan.The results are described as follows. 1. The aboveground biomass of E. nutans in the 2 year old artificial grassland was highest and the index of grassland quality (IGQ) was highest in the 2 and 3 year old communities, whereas it decreased in the other communities. IGQ was the lowest in the 7 year old community. 2.The number and diversity of E.nutans species in the artificial grassland communities increased with the age increase of the communities but differed in their patterns of increase. 3. The decrease in biomass of E.nutans and IGQ correlated with the decrease of available phosphorus and not with the concentration of nitrogen in soil. The time for utilization of the artificial grassland with E.nutans could be lengthened by additional phosphorus supplement in soil.