黄河源地区植被净初级生产力对气候变化的响应

基于黄河源区1959—2008年月平均气温、最高气温、最低气温、相对湿度、降水量、风速和日照百分率等气候要素资料,应用修订的Thornthwaite Memorial模型计算了50 a植被净初级生产力(NPP),分析其年际和年代际变化特征及其对气候变化的响应。结果表明:1959—2008年间,研究区年NPP变化呈显著上升趋势,NPP变化曲线线性拟合倾向率在95.502～190.72 kg/(hm2.10a)之间,20世纪90年代后NPP较高。20世纪70年代表现为"冷干型"气候特征,NPP距平百分率偏少1.1%～2.1%;2001—2008年均为"暖湿型"气候特征,NPP距平百分率偏多2.1%～4.5%。影响黄河源区NPP变化的主要气候因子是降水量、最大蒸散量和平均最低气温。"暖湿型"气候对植被净生产力增加最有利,黄河源区NPP可增加5.5%～8.5%。而"冷干型"气候造成植被净生产力下降5%～9%。若2050年在"暖湿型"气候情景下,黄河源区未来NPP较多年平均值增加7%～17%。

Responses of net primary productivity of natural vegetation to climatic changes in the source region of the Yellow River

Based on observational climatic data of monthly average temperature,maximum temperature,minimum temperature,relative humidity,precipitation,wind speed and sunshine duration in the source region of Yellow River in 1959—2008,the net primary productivity(NPP) for 50 years was computed with the application of revised Thornthwaite Memorial Model.In addition,the inter-annual change and the seasonal difference of NPP were analyzed,and the responses of net primary productivity to climatic changes was discussed as well.The main results were as follows: In 1959—2008,the annual NPP in this region had an increasing trend,with a linear fitting rate of annual NPP change curves being 95.502~190.72 kg/(hm2·10a),the NPP appeared a high rate mostly after 1990s.The cold and dry climate occurred in the 1970s,the NPP of which was 1.1%~2.1% less than the annual average NPP;and the warm and wet climate appeared in 2001—2008,the NPP of which was 1.1%~2.1% more than the annual average NPP.The main factors which influenced the NPP were precipitation,maximum evapotranspiration and average minimum temperature.The warm and wet climate benefited the growth of the NPP with an average increment of yield by 5.5%~8.5% in the source region of the Yellow River,while the cold and dry climate had an adverse impact on NPP with an average reduction of yield by 5%~9%.If the future climate in the region would become warm and moist,the NPP could increase by 7%~17% in 2050.