Agroecosystem composition and landscape ecological risk evolution of rice terraces in the southern mountains, China

Abstract

Mountain rice terrace agriculture is a critical land use practice in southern China. Analyzing the vertical structure of rice terraces systems and the coupled evolution of their human-land relationship from a mountainous stereoscopic perspective is significant to regional resource use and sustainable agricultural development. This study took the Xijiang Township and Jiabang Township in the mountainous area of Southwest China as the research object, based on the unique rice farming environment in the mountainous region, to divide the typical types of the four-element isomorphic (FEI) of the regional forest, village, river, and rice terraces from the perspective of vertical differentiation. The spatiotemporal evolution characteristics of rice terraces based on the view of the social-ecological system were explored by using the land use data of Jiabang Township from 1962 (1977 in Xijiang Township) to 2020, and methods such as mathematical statistics, sample transect analysis. The ecological risk model was also employed to analyze the spatiotemporal variation characteristics and landscape stability of ecological risk in mountain rice terraces systems. The study showed that: (1) The rice terraces showed the “forest-terraces-village-river” (F-T-V-R), “forest-village-terraces-river” (F-V-T-R), and “forest-terraces-village-terraces-river” (F-T-V-T-R), and the rice terraces in each differentiation type experienced a continuous evolutionary feature of “development-stabilization-local shrinkage and shifted.” (2) The mixed production trend of “main rice and the auxiliary dry land” in the rice terraces landscape was gradually highlighted, and the degree of landscape abandonment and fragmentation was deepened, and the “F-T-V-T-R” structure had the highest landscape stability in long-term development. (3) The ecological risks of each landscape type showed the characteristics of “increase-stabilization-decrease” in different time series evolution. (4) Although the “F-T-V-T-R” landscape types in the two areas were at a high-risk level in the long term, the long-term changes are less fluctuating, and the landscape security stability is the highest. The research results comprehensively reflected the spatiotemporal evolution characteristics of the landscape spatial pattern of rice terraces, and revealed the reflection of the FEI vertical differentiation structure on the regional social ecosystem and human-land relationship, which can help us to promote the optimal utilization of traditional rice terraces resources in the mountains and promote the sustainable development of rice agriculture.