An Assessment of Outmigration-related Land Use Transition in Rural Area and Corresponding Social and Ecological Dynamics - A Case Study in Southwest China
China’s urbanisation rate has been rapidly increasing for decades (increased by about 40% during 1978-2017). This expansion has led to massive outmigration in rural regions, which has changed regional labour force structure and local landscape patterns and resulted in a series of social, agricultural, and ecological dynamics. Given the small-scale household-based agriculture pattern in rural regions, scarce arable land resources and high demand for grain in China, this is a phenomenon worth a serious attention. However, the outmigration-related land use transition in rural China and its impacts have often been neglected. This research used a case study in southwest China to investigate how regional land use patterns have been changed in the context of rural outmigration and assessed the resulting dynamics on local society, agriculture, and the ecological environment. This research used remote sensing data and employed relevant data analysis tools to assess and map land use transition and ecological dynamics in the study area during 2000-2018. Regional climatic data, agricultural data and socio-economic data were fully analysed to explore the driving mechanisms behind such transition processes. The key findings include: (1) The local land conversion process was mainly characterised by the conversion of farmland (-18.3%) to residential area (+268.3%) and woodland (+55.6%) during 2000-2018; (2) About 83.7% of area showed a statistically significant increase of NDVI. This trend was not due to human interference factors (e.g. afforestation) but was mainly caused by the combined effects of depopulation (R = -0.514, P < 0.01) and a warming climate (R = 0.505, P < 0.01). Only 2.5% of area had decreased NDVI and this was directly caused by human activities (e.g. urban area expansion); (3) Local agricultural activities were initially affected (e.g. productions of grain crops and oil-bearing crops decreased by 14.5% and 9.7%) by a rural exodus and reduction of farmland during 2000-2009, but this impact has been gradually mitigated due to the development of industrialisation and mechanised agriculture during 2009-2018. Cash crops (e.g. vegetables) have been more widely grown (+76.0%) to meet the growing nutritional needs of the population. The case study has several implications for the rural sustainability in southwest China. Firstly, thanks to the development of agricultural techniques, increased grain production in other regions of China and grains imported from abroad, regional food security of southwest China has not been largely threatened by the population outflow and farmland reduction. Secondly, it could be a good choice to allow those high-slope and biophysically poor farmlands to undergo natural ecological evolution rather than cultivation. Farmers in southwest China should make a full use of the existing low-slope arable land and curb the declining trend to meet the challenges brought by urbanisation. Enhanced agricultural infrastructure, mechanised farming and guide from local government can help achieve this goal. This study provided new insights and more realistic scenarios for rural development in southwest China. The research findings are expected to provide a better understanding to enable sustainable land use management in southwest China.
Land use and land cover change, Urbanisation, NDVI, Rural outmigration, Mann-Kendall test, Linear regression, Southwest China
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