2000—2010年石羊河流域NPP时空变化及驱动因子

Spatiotemporal variations of vegetation NPP and related driving factors in Shiyang River basin of Northwest China in 2000-2010

基于MODIS卫星遥感数据,研究石羊河流域2000—2010年植被NPP的时空分布与变异特征,分析其与气候变化和人为影响的关系,并建立NPP人为影响模型。结果表明:石羊河流域NPP总量先升后降,在2002年达到顶点,再逐年下降,但下降过程中呈现一种周期起伏特征;整体来看,NPP变化与降雨呈明显的正相关性,与气温相关性不明显;局部地区来看,NPP与降雨显著相关,有些地区NPP与气温相关性也较强;年降雨量相关分界线为380与170mm,>380mm的地区气温为主导因子,介于170～380m的地区主导因子是降雨,<170mm的地区,降雨与人为影响共同主导。分析表明,2000—2010年,在人为作用下,石羊河流域植被NPP值年际增加量为2353.86gC·m-2·a-1,表明该流域生态环境治理工程实施后,植被覆盖状况得到一定的改善。从植被类型来看,草地受人为影响的正向与负向作用均最为剧烈;农田受人为影响也很明显,耕种方式的改进与管理措施提高使NPP增加;绿洲边缘的戈壁植被、盐碱地植被、沙地植被、林地等受人为影响基本为正向,植被覆盖面积与质量均有所增加。

By using MODIS remote sensing data, this paper studied the spatiotemporal distribu- tion and variation characteristics of vegetation net primary productivity （NPP） and their relation- ships with climate change and human activity in the Shiyang River basin of Northwest China in 2000-2010, with the human effect model of NPP established. In 2000-2010, the total vegeta- tion NPP in the basin decreased after an initial increase, with the peak in 2002 and a periodical fluctuation in the decreasing process. Overall, the NPP had a significant positive correlation with precipitation, but less correlation with air temperature; whereas in some areas, the NPP had sig- nificant correlation with precipitation, and also, stronger correlation with air temperature. The re- lated division lines for the annual precipitation were 380 mm and 170 mm. In the areas with the annual precipitation greater than 380 ram, air temperature was the dominant factor affecting the NPP; in the areas where the annual precipitation was 170-380 mm, precipitation was the domi- nant factor; and in the areas with the annual precipitation less than 170 mm, precipitation and human activity were the primary factors. Under the effects of human activity, the annual increment of the NPP in the basin in 2000-2010 was averagely 2353.86 g C · m-2 · a-1, sugges- ting that the vegetation coverage in the basin was improved to some extent after the eco-environ- ment management project was implemented. From the view point of vegetation type, grassland was most acutely positively and negatively affected human activity, cropland was also very obvi- ously affected by human activity, and the cropland NPP was increased by the improvement of cul-tivation and management measures, whereas the Gobi, saline and alkaline land, sand land, and forestland in the oasis edges were basically positively affected by human activity, their vegetation coverage and quality being somewhat increased.