Spatio-temporal evolution characteristics of agro-ecosystem adaptability response to global change in South China hilly regions: A case study of Hengyang Basin

There is renewed interest in the evolution of the adaptability of ecosystem to global change. It is important to study rice farming regions in hilly areas of Hengyang Basin. As a rice-based agricultural region, it is very important to study the adaptability of agricultural ecosystem (AAE) in South China. Previous studies have shown that in Hengyang Basin, a typical agricultural ecosystem in South China, obvious spatial distribution patterns of AAE were higher in periphery regions and lower in the middle regions of the basin. However, the temporal and spatial variation characteristics of AAE were not completely clear. This research used Hengyang Basin as a case study to build the evaluation index system consisting of 12 indicators ranging from natural to social and then to economic aspects. The evaluation unit consisted of Hengyang Basin and the surrounding counties. The AAE index for Hengyang Basin was calculated using an entropy method and 16 years of data (1999-2014) to determine index weight. The results showed that a complex and highly different spatio-temporal variations in AAE in Hengyang Basin for the different counties and different years. However, the range of the AAE index for the eight counties (cities) in the basin was 0.249 8-0.679 4, which indicated a medium and high AAE level in the region. In the eight counties (cities), Leiyang City had the highest AAE, followed by Qidong County, and Changning County was the weakest. The coefficients of variation for the different counties (cities) showed that change in AAE was highest for Changning City and lowest for Hengnan County for the period 1999-2014. There was a wave-like trend in AAE for Leiyang City with rises and falls. The evaluated 16 years was divided into three periods-the period 1999-2004 was the period of low index and small amplitude oscillation, the period 2005-2010 was the one of an overall rise with significant fluctuation in adaptability, and then the period 2010-2014 was the period of rapid rise AAE index. The conclusions in this study provided a useful reference to guide sustainable agricultural development in the hilly regions of South China.