张掖市典型绿洲农田生态系统生产力时空分布特征

目的]以甘肃省张掖市甘州区典型绿洲为例,研究绿洲农田生产力的时空格局及其全球变化对农田生产力的影响,为区域农业资源管理决策与规划提供决策依据。方法]利用MOD17A3NPP产品、气象数据及甘州区农业统计等数据,结合GIS空间分析技术开展研究。结果]甘州区不同农田类型净初级生产力(NPP)均值最小值均出现在2001年,最大值出现在2007年。甘州区农田净初级生产力年均值变化范围为109.3~420.5g/(m~2·a),其分布特征与农田类型的空间分布基本一致;同一农田类型,高海拔区农田生产力小于海拔较低区,即农田生产力的大小是由农田类型及海拔高度共同决定的。NPP变化趋势存在明显的空间异质性,农田生产力增加的面积占总面积的40.9%,主要是旱地和高海拔地区的水浇地。海拔1 800m以上的旱地和水浇地年降水量的增加趋势远大于平均气温,其NPP呈明显的增加趋势。结论]近10a来甘州区农田生态系统生产力存在明显的时空差异,整个旱地和水浇地年均NPP呈增加趋势,水田年均NPP呈下降趋势。

Spatial-temporal Distribution Characteristics of Farmland Ecosystem Productivity of Typical Oasis in Zhangye City

Objective] Taking the typical oasis of Ganzhou District of Zhangye City, Gansu Province as an example, the temporal and spatial pattern of farmland productivity in that oasis and the effect of global change on the farmland productivity were researched, to provide decision-making basis for regional agricultural resource management and planning. Methods] Using the data such as MOD17A3 NPP product, meteorological data and agricultural statistics data, the research was conducted by GIS spatial analysis technology. Results] The minimum and maximum values of different types of net primary productivity(NPP) in Ganzhou District appeared in 2001 and 2007 respectively. The range of annual average farmland NPP in Ganzhou District was 109.3~420.5 g/(m²·a), and its spatial distribution was approximately consistent with the farmland. For same type of farmland, its productivity of high elevation area was less than that of low elevation. All of which indicated that the agricultural productivity was determined by both of farmland type and altitude. The NPP trend had an obvious spatial heterogeneity. Area of increased agricultural productivity covered 40.9% of the total area, among which, the mainly increased types were dry land and irrigated cropland in high altitude region. The dry land and irrigated cropland above 1 800 m had a higher increasing trend of annual precipitation than that of average temperature, which made the NPP a significant increasing trend. Conclusion] The ecosystem productivity of Ganzhou District from 2001 to 2010 had obvious spatial and temporal differences, the annual NPP of dry land and irrigated cropland exhibited an increasing trend, while the paddy NPP showed a decreasing trend.