基于LUE模型的长江源流域NPP时空变化特征分析

Spatial and Temporal Analysis of NPP Characters in Headwater Region of Yangtze River

长江源流域具有独特的高寒植被生态系统,研究植被净初级生产力变化及其与气候因子的关系,能够反映生态系统对全球变化的响应。利用改进的遥感光能利用率模型(LUE)模拟了2001-2010年长江源流域植被NPP时空变化特征,结合同期气温和降水数据,运用趋势分析法和偏相关分析法,研究了植被NPP对气候因子的响应特征。结果表明:1)植被多年平均NPP值为171.83gC/m^2/a,高寒针叶林NPP值最大(392.64gC/m^2/a),高寒草原最小(70.41gC/m^2/a)。而高寒草甸和高寒草原分布最广,占植被NPP总量的86.6%。2)植被NPP呈增加的趋势(6.39gC/m^2/a),增加趋势不显著,在水热条件的影响下,植被NPP增长呈现出空间异质性,增加幅度由东南向西北逐渐减少。不同植被类型的NPP增长趋势不同,其中高寒针叶林、灌丛、高寒草甸、高寒草原和高山垫状植被的NPP增长率分别为15.98、12.61、3.13、2.69和1.01gC/m^2/a。3)植被NPP相比于降水,对温度的敏感性更高。近10a温度的显著增加是导致植被NPP增加的主要因素。研究结果有利于把握长江源流域高寒生态系统功能特征,为生态规划建设提供科学依据。

Unique alpine ecosystem is in the source region of Yangtze River, to study the alpine vegetation net primary production （NPP） change and relationship to climate factors is considered to reflect alpine eco- system responses to global climate changes. In this study, the light use efficiency model based on remote sensing data was used to simulate the NPP from 2001 to 2010 in the resource region of Yangtze River,the relationships between NPP and climate factors were also analyzed. The results indicated that：l） mean an- nual vegetation NPP was 171. 83 gC/m2/a, while the biggest NPP type was alpine coniferous forest （392.64 gC/m2/a） and alpine steppe was the lowest NPP （70.41 gC/m2/a）. The NPP of alpine grasslands that were most widely distributed in the area accounted for 86. 6% of the total. 2） Vegetation NPP increased by 6.39 gC/m2/a, but not significantly. The increase range decreased from southeast to northwest. NPP increase trend in alpine coniferous forest, scrubs, alpine meadow, alpine steppe and alpine vegetation were 15.98,12.61,3.13,2.69 ,and 1.01 gC/m2/a,respectively. 3） Vegetation NPP was more sensitive to temperature than precipitation,the increase temperature was the key factor for the NPP increase from 2001 to 2010. The results of this study would be beneficial for the understanding of the alpine ecosystem characters in the resource region of Yangtze River,and could provide the scientific basis for the design and devel- opment of the ecosystem.