1975-2015年宁夏生态系统格局宏观变化分析

以1975-2015年的Landsat MSS/TM/OLI影像为数据源，选用年均生态系统类型净变化率、生态系统类型转移矩阵及土地开发度综合指数对宁夏回族自治区近40年来生态系统格局宏观变化的幅度、速率、转换类型及人类活动扰动程度进行定量分析，揭示了宁夏生态系统时空变化过程及其区域分异性。研究结果表明：（1）宁夏农田和草地生态系统优势度较大，占比75%以上，且两者面积变化趋势呈负相关。近40年中，森林净增加了477.5 km²，人工表面净增加了884.6 km²，农田净增加了209.8 km²；草地净减少了115.5 km²，湿地净减少了69.4 km²，荒漠净减少了1387.0 km²。（2）生态系统变化转移矩阵表明每时段内大约有占宁夏总土地面积6%的生态系统面积发生变化，主要转换类型有农田和草地间相互转换、草地和荒漠转为农田及农田转为草地和人工表面。（3）人为活动对生态系统的干扰全区整体处于我国的中等水平，且呈增加趋势，其中北部是持续增强，且金凤区、西夏区和永宁县土地开发效果最为明显，中部是轻微减轻，南部是显著减轻，人类活动对宁夏北部和中部自然生态系统的扰动大于南部。

Macro analysis of spatiotemporal variations in ecosystems from 1975 to 2015 in Ningxia Hui Autonomous Region of China

Landsat MSS/TM/OLI images from 1975 to 2015 were used as main data sources to derive the spatiotemporal patterns of ecosystems in Ningxia Hui Autonomous Region. The amplitude, rate, transition types, and regional differentiation of the spatiotemporal changes and human activity disturbance of the ecosystem in Ningxia over the past 40 years were analyzed using the annual net area change rate, transfer matrix, and the land development degree comprehensive index, thus the spatiotemporal changes of the ecosystem patterns in the study area and its regional heterogeneity were revealed finally. The results showed that (1) farmland and grassland accounted for more than 75% of the total area and showed a negative correlation between their area change trends. Over the last 40 years, forestland, artificial surface, and farmland showed net increases of 477.5 km², 884.6 km², and 209.8 km², respectively, while grassland, wetland, and desert showed net decreases of 115.5 km², 69.4 km², and 1387.0 km², respectively. (2) The result of ecosystem transition matrix indicated that about 6% of the ecosystem area in the whole district had changed over each period. The three main conversion types were the mutual conversions between farmland and grassland, the transfers from grassland and desert to farmland, and the transfers from farmland to grassland and artificial surface. (3) The degree of human activity disturbance continued to increase in the northern region, and land development effects were most pronounced in Jinfeng District, Xixia District and Yongning County, while the central region showed a slight reduction, and the southern region showed a significant reduction, indicating that human activities had greater disturbance to the ecosystems in the northern and central parts of Ningxia.