基于地理探测器的岷江中下游地区植被NPP时空格局演变及其驱动力研究

植被净初级生产力作为反映植被生态系统对气候变化响应的重要指标,是长期以来备受世界各国关注的焦点问题。论文以岷江中下游地区为研究区域,基于2000—2015年MODIS NPP数据,结合同年期海拔、气温、降水、土地利用类型等,运用地理探测器等模型方法,诊断植被NPP分布的主要驱动力,并揭示了不同时段的驱动力决定力的变化。结果表明:(1)2000—2015年岷江中下游植被NPP平均值为513.93gC/m~2;植被年均NPP最大值出现在2000年石棉县北部硗碛藏族乡的林地分布区,为1876gC/m~2,最小值出现在2005年五通桥区中部竹根镇的平原旱地分布区,最小值为26.98gC/m~2;植被NPP具有较强的时空分异性,NPP总量变化除了受NPP强度影响外,植被覆盖总面积是其另外主要的影响因素。(2)影响植被NPP分布的主导因素包括气温、海拔、土地利用等,各因素对NPP分布的决定力存在明显差异。(3)不同时间植被NPP空间分布的驱动力存在明显差异,主要表现在其变化受人类扰动的影响越来越强烈。刻画岷江中下游植被NPP时空演变,并揭示其主要驱动力,可为研究区生态安全预警和生态补偿提供数据支撑和辅助决策。

The spatial and temporal pattern evolution of vegetation NPP and its driving forces in middle-lower areas of the Min river based on geographical detector analyses

Vegetation net primary productivity (NPP) is considered a key factor of ecological responses to climate change, so it has long aroused attention from countries around the world. Using the middle-lower Area of the Min river as the study area, the Geodetector model was applied based on MODIS NPP products from 2000 to 2015, as well as annual altitude, temperature, precipitation, and land use date in the same period to diagnose the dominant factors of spatial distribution of vegetation NPP change and reveal the different time changes of driving forces determining vegetation NPP differentiation. The results showed that 1) The average annual NPP for the middle-lower Area of the Min river was 513.93 gC/m² from 2000 to 2015. The maximum and minimum values (1876 gC/m² and 26.98 gC/m) observed in 2000 in the Qiaoqi Tibetan township north of Shimian county and 2005 in the plain dryland distribution area of Zhugen Town in the middle of Wutongqiao showed a strong spatiotemporal variability in the middle-lower Area of the Min river. In addition to the NPP intensity, the total area covered by vegetation was the other major influencing factor. 2) The dominant factors affecting vegetation NPP spatial distribution included temperature, altitude, and land use, and their power determinant value to NPP incidence differentiation. 3) These factors affect the changes in vegetation NPP from different perspectives and their driving forces differ over the years. The changes in vegetation NPP mainly presented more and more concerned by human disturbances. On the contrary, it is weakened by natural factors. Spatiotemporal changes of NPP and its driving forces were revealed. The findings provided the data and assistant decision-making for the government to formulate policies regarding ecological security alarm and ecological compensation.