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The study of soil bacterial community structure and functional groups in rice terraces can provide a theoretical basis for the sustainable management of terraces. Nineteen soil samples were collected at different altitudes in Longji rice terraces. Bacterial community structure was analyzed using 16S rRNA high-throughput sequencing, and its functional group was predicted using FAPROTAX functional prediction software. The results showed that the dominant phyla were Proteobacteria and Chloroflexi with 37.40%~63.28% and 11.30%~ 40.78% abundance, respectively. The dominant genera were Sphingomonas and Rhodanobacter with 7.13%~20.87% and 2.34%~21.53% abundance, respectively. Clustering heatmap of dominance operational taxonomic units（OTUs）showed that the environmental factors significantly related to bacterial abundance were pH, carbon–nitrogen ratio（C/N）, alkali-hydrolyzed nitrogen（AN）, and altitude. A total of 51 functional groups were predicted based on all the OTUs. Denitrification, sulfur respiration, and hydrocarbon degradation functional groups were significantly related to pH, C/N, AN, and altitude. The above results indicated that soil pH, C/N, AN, and altitude significantly affected soil bacterial community structure and functional groups in Longji rice terraces. [ABSTRACT FROM AUTHOR]

This paper investigates transformations and trends in a traditional agricultural system in Kiangan, Philippines as a consequence of evolving social-ecological scenarios. For this study, Modified Sustainable Livelihood Framework (MSLF) and Drivers-Pressures-State-Impacts-Responses (DPSIR) framework identified major driving forces in Kiangan social-ecological system (SES) and elucidated relationships and interactions between them. This study however unveiled the highly disturbed state of Kiangan SES and erosion of Ifugao culture and belief systems owing to the ingress of modernization, mind-set change among locals and weak institutional support. In particular, the polytheism to Christianity shift was a causative factor leading to abandonment of traditional rice varieties and farming rituals as well as the transformation of Kiangan upland landscape and its associated biophysical structures. Furthermore, productivity-driven approach to food production also resulted in wide scale agro-biodiversity losses, environmental degradation and cultural erosion. It was nonetheless observed that the Kiangan SES has, as of this time, not yet shifted to an alternative state and is still able to conserve its main features despite pressures to it. Interventions are therefore warranted to redirect the trajectory of Kiangan SES, steer it toward sustainable agricultural development and consequently into its preservation on behalf of the people that depend on it for food and livelihood. [ABSTRACT FROM AUTHOR]

• A framework for socio-ecological analysis of rice terrace systems is constructed. • Assessed the degree of ecological risk in the rice landscape. • Three specific "four-element isomorphism" rice terraces ecosystems have been formed. • The "forest-terraces-village-terraces-river" landscape structure is the most stable. • High sustainability of agricultural terraces in a virtuous social-ecological system. 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. [ABSTRACT FROM AUTHOR]