巴西土地利用/覆盖变化时空格局及驱动因素

Spatiotemporal pattern and driving forces of land use/cover change in Brazil

土地利用/覆盖变化(LUCC)是全球变化研究的热点问题之一。本文采用人机交互方法基于2005年基准年的Landsat TM/ETM遥感影像修正欧空局Global Cover 2005年土地利用数据,进而采用逆时相目视解译法从1980年基准年的Landsat MSS/TM遥感影像数据提取1980-2005年土地利用/覆盖变化信息,分析其变化的时空格局及驱动因素。结果表明:1980-2005年的25年间,巴西土地利用/覆盖变化面积达79.43万km2,占土地总面积的9.33%。其中,单纯耕地像元面积增加了20.18万km2;耕地/自然植被镶嵌混合像元区面积增加了10.70万km2;林地面积减少了53.12万km2;灌丛与草地净增加21.10万km2;水体面积增加0.46万km2;城乡建设用地面积增加7573.87 km2。由此导致热带和亚热带湿润阔叶林生态地理区、热带和亚热带干旱阔叶林生态地理区、热带及亚热带草原生态地理区、草原和沼泽湿地生态地理区、沙漠和旱生植物生态地理区以及红树林生态地理区内分别呈现不同的土地利用/覆盖变化特征。近25年间,地形地貌、气候、植被等自然地理条件深刻影响着土地利用的宏观格局,而土地利用政策调控、经济及对外贸易发展、人口增加及空间迁移、道路修建等是导致巴西土地利用变化的主要原因。

Land use/cover change(LUCC) is one of the hot topics in the study of global change. In this research,the authors adopted the method of human-computer interaction to amend the 2005 ESA Global Cover land use data based on the Landsat TM/ETM remotely sensed data around 2005, then used the inverse phase visual interpretation method to extract land use/cover change information between 1980 and 2005 based on the Landsat MSS/TM remotely sensed data in the 1980 s, and analyzed the Spatiotemporal pattern and driving forces of the change.The results show that in the 25 years between 1980 and 2005, that area of land use/cover change reached 794300km2 in Brazil, accounting for 9.33% of the total land area. Among these, cropland increased by 201800 km2, cropland/natural vegetation mosaic increased by 107000 km2, forest area decreased by 531200 km2, shrub and grassland converted to other land use types by 236000 km2 and the opposite conversion was 447000 km2 with a net increase of this land use category by 211000 km2, water increased by 4600 km2, urban and built-up areas extended by 7573.87 km2. But the land use macroscopic structure did not change. Regional differences of the main land use change forms including deforestation, grassland in- and out- conversion, Land reclamation, and urban and built- up area expansion led to different land use/cover change characteristics in tropical and subtropical moist broadleaf forest ecological zone, tropical and subtropical dry broadleaf forest ecological zone, tropical and subtropical steppe ecological zone, grassland and marsh wetland ecological zone, desert and xeric plants ecological zone, and mangrove forest ecological zone. Natural geographical conditions such as landform, climate, and vegetation profoundly affected the macro pattern of land use and the possibility of land use change. Although climate change had a certain impact on cropland reclamation and the increase of grassland, land use policy, economy and foreign trade development, population growth and migration, and road construction were the direct causes of land use change in Brazil.