江河源地区草地植被变化特征及水土保持功能评价

利用青海省江河源地区河南、曲麻莱、甘德3个牧业气象观测站1995-2004年的定位观测资料,从牧草生育期、高度、产量和种群结构4个方面分析了青海江河源地区的草地变化特征,结果表明:由于牧草的返青期和枯黄期发生变化,使得江河源地区的牧草生育期延长了3～5 d.综合分析江河源地区牧草高度、产量和种群结构发现,长江源区的曲麻莱牧草退化趋势和程度较小,而河源区的牧草均呈现一定的退化趋势,尤以河南显著.通过分析由植被覆盖度换算得出的草地水土保持系数发现,从东往西呈现逐渐减小的趋势,低值区出现在玉树州的治多县,高值区出现在黄南州的河南县.久治县、班玛县、甘德县、河南县和泽库县草地水土保持功能较好,治多县为差区,其他地区为较差区.

The change characteristics of grassland vegetation and the assessment of grassland function on water and soil conservation in the source regions of Yangtse River and Yellow River

Using from 1995 to 2004 the observation data fixing position in 3 animal husbandry meteorological observation stations-Henan,Qumalai, Gande of the source regions of Yangtse River and Yellow River,The change characteristics of grass growth stages,height,yield and population structure were analyzed.The results indicated that the grass regreening stage and withering stage changed,what resulted in grass growth stage prolong 3 to 5 days.According to the analysis about grass height,yield and population structure,the tendency and the degree of grass degraded were weak in Qumalai of source region of Yangtse River;but grass in the source region of Yellow River displayed the certain degradation trend,and the grass degradation in Henan was especially remarkable.Through analyzing the coefficient of the grassland water and soil conservation computed by the vegetation coverage,we found that the mean index of coefficient was 0.66 in the source regions of Yangtse River and Yellow River,and from east to west it appeared the diminishing tendency,and the low value appeared in Zhiduo county,and the high value was in Henan county.The grassland function on water and soil conservation was good in Jiuzhi county,Banma county,Gande county,Henan county and Zeku county,and it was poor in Zhiduo county,and in the other regions it was relatively poorer.