China's land cover and land use change from 1700 to 2005: Estimations from high‐resolution satellite data and historical archives
One of the major limitations in assessing the impacts of human activities on globalbiogeochemical cycles and climate is a shortage of reliable data on historical landcover and land use change (LCLUC). China had extreme discrepancies in estimatingcontemporary and historical patterns of LCLUC over the last 3 centuries because of itsgeographical complexity, long history of land use, and limited national surveys. Thisstudy aims to characterize the spatial and temporal patterns of China’s LCLUC during1700–2005 by reconstructing historical gridded data sets from high‐resolution satellitedata and long‐term historical survey data. During this 300 year period, the majorcharacteristics of LCLUC in China have been shrinking forest (decreased by 22%) andexpanding cropland (increased by 42%) and urban areas (including urban and ruralsettlements, factories, quarries, mining, and other built‐up land). New cropland areas havecome almost equally from both forested and nonforested land. This study also revealed thatsubstantial conversion between forest and woodland can be attributed to forest harvest,forest regeneration, and land degradation. During 1980–2005, LCLUC was characterizedby shrinking cropland, expanding urban and forest areas, and large decadal variations on anational level. LCLUC in China showed significant spatial variations during differenttime periods, which were caused by spatial heterogeneity in vegetation, soils, and climateand regional imbalance in economy development. During 1700–2005, forests shrunkrapidly while croplands expanded in the northeast and southwest of China. During 1980–2005, we found a serious loss of cropland and urban sprawl in the eastern plain, north, andsoutheast regions of China and a large increase in forested area in the southeast andsouthwest regions. The reconstructed LCLUC data sets from this study could be used toassess the impacts of land use change on biogeochemical cycles, the water cycle, and theregional climate in China. To further eliminate uncertainties in this data set and makereliable projections of LCLUC for the future, we need to improve our understanding of thedrivers of LCLUC and work toward developing an advanced, spatially explicit land usemodel.