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Agricultural landscape change in China's Yangtze Delta, 1942-2002: A case study

Wu, Jun-Xi, Cheng, Xu, Xiao, Hong-Sheng, Wang, Hongqing, Yang, Lin-Zhang, Ellis, Erle C.
Agriculture, ecosystems & environment 2009 v.129 no.4 pp. 523-533
agricultural land, agroecosystems, landscapes, temporal variation, agricultural history, case studies, villages, population density, rural policy, intensive farming, land use change, land use, forests, aquaculture, fields, agricultural policy, land management, China
Over the past 60 years, China's ancient agricultural village landscapes have been transformed by unprecedented changes in rural policy, population and agricultural technology. The village landscapes of China's Yangtze Plain are among the most ancient, densely populated and intensively managed in the world and have undergone extremely rapid development in recent decades, causing the wholesale transformation of traditional village landscape structure, primarily at fine spatial scales (< 30m). Here we investigate the causes and consequences of these fine-scale changes, 1942-2002, using a case study of landscape change within a regionally representative sample of village landscapes in Yixing County. High-resolution mapping was coupled with historical data obtained by interviews with elder farmers and archival sources, with uncertainties quantified using Monte Carlo methods. The already dense agricultural populations of 1942 had increased by about 50% by 2002, and this was accompanied by an intensification of land management that caused 53% of land area to undergo a substantial change in landscape class. Paddy area declined by 22% from 1942 to 2002, and this was coupled with an 8% net increase in built surfaces, a 14% increase in aquaculture surface, and most surprisingly, by a 5% net increase in land cover by closed canopy woody vegetation. Most of this change was caused by fine-scale land transformations that fragmented larger managed features into smaller features that incorporated a wider variety of management practices, thereby simultaneously increasing both landscape heterogeneity and complexity. Population growth, agricultural policy changes and market-oriented land management strategies combined to produce these significant long-term agricultural landscape changes. By coupling detailed analysis of fine-scale local landscape transformation processes with land use history across three time periods, this study identified the causes of ecologically significant landscape changes and may also help to indicate future change trends within some of the most densely populated and productive agricultural landscapes in the world.