汾河流域植被生产力时空变异特征分析

Spatial and Temporal Variation Characteristics of Vegetation Productivity in Fen River Basin

植被生产力(GPP、NPP)和碳利用效率(CUE)是监测和评估生态系统的重要指标,能够有效反应生态系统环境变化。汾河流域是黄土高原典型生态脆弱区的重要流域,是全国水土流失治理和生态保护的重点区域。本研究以流域尺度为出发点,基于MODIS数据重点分析了汾河流域2000—2015年GPP、NPP和CUE的时空特征及影响因素。结果表明:汾河流域整体上GPP和NPP呈现增加的趋势,而CUE则表现为减少趋势,平均值为GPP 665.88 g C/(m^(2)·a),NPP 252.77 g C/(m^(2)·a),CUE 0.36。GPP、NPP和CUE南部高于北部地区,流域边缘两侧山地与其他区域明显不同。汾河流域植被生产力状况主要受降水的影响较大。北部GPP、NPP、CUE与气温主要呈现负相关关系,而在流域南部,GPP与气温呈正相关关系,NPP、CUE与气温呈负相关关系。汾河流域北部对水热条件变化比南部更加敏感,同时汾河流域气温和降水的增加导致了CUE降低。

Vegetation productivity(GPP,NPP)and carbon use efficiency(CUE)are important indicators for monitoring and assessing ecosystems,which can effectively reflect changes in the ecosystem environment.The Fen River Basin is an important watershed in the typical ecologically fragile area of the Loess Plateau,and a key area for soil erosion control and ecological protection in China.This study took the basin scale as the basis and focused on analyzing the temporal and spatial characteristics and influencing factors of GPP,NPP and CUE based on MODIS data in the Fen River Basin from 2000 to 2015.The results showed that GPP and NPP presented increasing trends in the Fen River Basin as a whole,while CUE had a decreasing tendency,with an average value of GPP 665.88 g C/(m^(2)·a),NPP 252.77 g C/(m^(2)·a)and CUE 0.36.The southern part of the basin had higher GPP,NPP and CUE than the northern part,and the mountains on both sides of the basin edge were obviously different from other areas.The vegetation productivity of the Fen River Basin was mainly affected by precipitation.In the north,GPP,NPP,and CUE were negatively correlated with temperature,while in the southern part of the basin,GPP was positively correlated with temperature,and NPP and CUE were negatively correlated with temperature.The northern part of the Fen River Basin was more sensitive to the changes of water and heat condition than the southern part,and the increase of temperature and precipitation in the Fen River Basin led to the decrease of CUE.