2000~2020年巴基斯坦土地生产力演变趋势及对气候的响应
Evolution Trend of Land Productivity and Its Response to Climate in Pakistan from 2000 to 2020

土地生产力是土地重要功能之一，能够有效反映土地资源质量状况。本文选取归一化植被指数(NDVI)以及气温、降水、水汽压等气象数据，利用趋势分析、显著性检验、Hurst指数以及相关分析等方法，逐像元分析，探讨了巴基斯坦地区2000~2020年土地生产力时空变化特征、变化趋势特征以及对自然因素的响应特征，结果表明：1) 从时间上看，2000~2020年巴基斯坦年均NDVI值呈波动上升趋势，波动范围为0.157~0.217，增速为0.022/10a。从空间上看，巴基斯坦NDVI主要呈现印度河流域及中东部平原地区高，西部高原、北部山地以及西南沙漠地区低的分布特征。2) 巴基斯坦2000~2020年土地生产力改善地区远大于退化地区，其中明显改善与轻微改善的区域分别占51.62%和15.19%，严重退化与轻微退化的区域分别占1.12%和2.70%，基本稳定区域为24.37%。巴基斯坦近一半区域土地生产力变化趋势具有反持续性。土地生产力持续退化区域占1.97%、由退化到改善区域占1.84%、基本稳定区占18.35%、由改善到退化区占34.34%、持续改善区面积占比最大为37.47%、变化趋势不确定区占10.53%。3) 降水是巴基斯坦地区最显著的影响因子，对土地生产力有明显的促进作用。西北部高原地区干旱严重，降水对土地生产力促进作用十分显著，而位于印度河流域的耕地，由于绝大多数处于灌溉区，土地生产力受降水影响相对较弱。其次为潜在蒸散水汽压、最高气温、最低气温，平均气温影响最弱。
Land productivity is one of the important functions of land, which can effectively reflect the quality of land resources. In this paper, the Normalized Vegetation Index (NDVI) and meteorological data such as air temperature, precipitation and water vapor pressure are selected and analyzed by means of trend analysis, significance test, Hurst index and correlation analysis to discuss the spatial-temporal change characteristics, change trend characteristics and response characteristics to natural factors of land productivity in Pakistan from 2000 to 2020. The results showed that: 1) In terms of time, from 2000 to 2020, the average annual NDVI value of Pakistan showed a fluctuating upward trend, with a fluctuation range of 0.157~0.217 and a growth rate of 0.022/10a. Spatially, NDVI in Pakistan is high in the Indus River Basin and the central and eastern plains, and low in the western plateau, the northern mountains and the southwest desert. 2) From 2000 to 2020, the land productivity improvement areas in Pakistan were far greater than the degraded areas, of which the areas with obvious improvement and slight improvement accounted for 51.62% and 15.19% respectively, the areas with severe degradation and slight degradation accounted for 1.12% and 2.70% respectively, and the basically stable areas accounted for 24.37%. The change trend of land productivity in nearly half of Pakistan is anti sustainable. The area of continuous degradation of land productivity accounts for 1.97%, the area from degradation to improvement accounts for 1.84%, the basic stable area accounts for 18.35%, the area from improvement to degradation accounts for 34.34%, the area of continuous improvement accounts for 37.47%, and the area of uncertain change trend accounts for 10.53%. 3) Precipitation is the most significant influencing factor in Pakistan, and it has an obvious promoting effect on land productivity. The northwest plateau area is seriously