三江源草地ANPP变化特征及其与气候因子和载畜量的关系

Dynamics of Grassland ANPP and Its' Relationship with Climate Change and Carrying Capacity in the Three River Headwater Region

在野外调查数据检验的基础上,采用CASA模型计算了2000~2014年三江源草地的地上净初级生产力(ANPP),进而分析了ANPP与气候因子和载畜量之间的关系。结果表明:2000~2014年三江源地区草地ANPP平均值为27.53gC/m2,其中75.81%的区域呈增加趋势,24.19%的区域呈减少趋势;整个三江源地区草地ANPP变化与年均温具有显著(P<0.01)的正相关关系,且在不同降水区域内ANPP随年均温的升高表现为先增加后减少;不同区域草地ANPP对年降水量的响应受温度的制约,在年均温>-2℃的区域ANPP随年降水量的增加而增加,年均温在-2^-6℃之间的区域表现为先增加后下降,而在年均温<-6℃的区域则无响应;三江源草地ANPP对载畜量的影响存在时间滞后性,与当年载畜量的相关性不明显,而与次年载畜量存在极显著的相关关系。

The grassland ANPP were calculated with CASA model and tested by field data in the Three River Headwater region from 2000 to 2014. The dynamics of grassland ANPP and its relationships with climatic factors （temperature, precipitation） and carrying capacity were analyzed. The results indicated that （1） average annual ANPP from 2000 to 2014 was 27.53 g C/m^2 in the Three River Headwater region, in where about 75.81% and 24.19% areas showed increasing and decreasing trends. （2） ANPP showed a significantly positive relationship with increased mean annual temperature if take the Three River Headwa- ter region as a whole, which showed a parabolic pattern with temperature under different precipitation. （3） the relationship of ANPP with precipitation depend on the temperature, which showed a positive pattern in where annual temperature above -2℃,but with no changes in where annual temperature below -6℃ ,and in the areas between -6- -2℃ showed a parabolic pattern. （4） the response of carrying capacity to ANPP of grassland in the Three River Headwater region had a time lag, ANPP did not show obviously correlation with current year＇s carrying capacity, while presented a significantly correlation with that of next year.