甘肃省县级行政单元NEP的时空异质性

Time and space variability of the county level administrative unit to NEP in Gansu Province

通过MODIS数据、气象数据和生态系统碳源/汇模型估算了甘肃省生态系统碳源/汇的空间分布,进行估算精度间接验证,结合人文因子和地理加权回归模型,在县(市/区)级行政单元上探讨生态系统碳源/汇的时空异质性和主要驱动因子.研究表明:甘肃省年均生态系统碳源/汇为-22.75~935.07 g/(cm^2·a),平均126.66 g/(cm^2·a),空间差异显著,呈现东南高西北低,从东南到西北呈递减趋势.年末总人口的回归系数总体上表现为西北高东南低,与年末总人口空间格局相反;地区生产总值对生态系统碳源/汇的影响与年末总人口的回归系数有所不同,既有正相关也有负相关关系,在数量上恰恰相反;第一产业对生态系统碳源/汇的影响表现出明显的负相关关系,第一产业的回归系数在西北和东南比较低,中间稍高;第二产业对生态系统碳源/汇的影响既有正相关关系也有负相关关系,西北高,东南低.甘肃省县级行政单元生态系统碳源/汇的影响因素与立地环境、资源禀赋、经济发展和政策措施等有关.

The spatial distribution of net ecosystem productivity in Gansu Province was simulated by the carbon source/sink model and series data sets of MODIS data and meteorological data, and the net eco- system productivity estimation precision was verified indirectly. The spatial and temporal heterogeneity of net ecosystem productivity and the main driving factors were investigated into by combining with humanities factor and geographically weighted regression model in county （county/city/district） level administrative unit. The result showed that the mean annual net ecosystem productivity value was -22.75 -935.07 g/（cm2. a） and its mean value was 126.66 g/（cm2. a）. The variation of the net ecosystem productiv- ity spatial distribution was significantly different between the high net ecosystem productivity value in the southeast and the low net ecosystem productivity value in northwest. The influence of the total population at year-end on the ecosystem carbon source/sink reflected that the variation was decreasing from the northwest high to southeast low, which was opposite to the spatial pattern of the total population at yearend. The gross regional production affected the ecosystem carbon source/sink and the two were of a posi- tive and negative correlation. The regression coefficient was just the opposite of the total population at year-end. The impact of the primary industry on the ecosystem carbon source/sink showed an obvious negative correlation, and regression coefficient of the primary industry was high in the middle but low in the southeast and northwest. The secondary industry had a positive and negative correlation with the ecosystem carbon source/sink, with a high in the northwest, but a low in the southeast. Many factors influenced the ecosystem carbon source/sink at the county-level administrative unit in Gansu Province, where the site environment was related to the resource endowment, economic development and relevant policies, etc.