Spatiotemporal variations in ecological quality and driving factors in agricultural land consolidation areas over the past 20 years: A case study of 267 projects in Qijiang District, Chongqing

Understanding the spatial and temporal differentiation of ecological quality in the context of agricultural land consolidation is essential for effective planning and decision-making. In this study, the spatial and temporal differentiation patterns and dynamic processes of ecological quality within the project area (267 agricultural land consolidation projects in the Qijiang District of Chongqing City) were investigated from 2000 to 2020 using a Remote Sensing-based Ecological Index (RSEI) model. A comparative analysis was conducted to assess the ecological quality characteristics of the project area in relation to varying frequencies of consolidation, thereby elucidating the factors contributing to the observed disparities in ecological quality across the agricultural land consolidation project sites. The results show that: 1) Over the past two decades, the ecological quality in the agricultural land consolidation project area of Qijiang District has been generally good, with the RSEI showing a “V” shaped trend, first declining and then rising, resulting in an overall improvement. Long-term agricultural land consolidation had a significant positive impact on regional ecological quality. During the implementation of phase 1 projects (2000–2010), some disturbance to the regional ecological environment was observed, whereas during the implementation of phase 2 projects (2011–2015) and phase 3 projects (2016–2020), ecological quality was promoted. From the perspective of project implementation, ecological quality showed a continuous optimization trend at 5, 10, and 15 a post-implementation, highlighting the lasting and profound impact of agricultural land consolidation projects on regional ecological restoration and optimization. 2) From 2000 to 2020, 267 project areas demonstrated good ecological quality, comprising > 55% of the overall project zone area. By contrast, regions classified as inferior or poor constituted less than 3% of the total area. Analysis of the various consolidation phases revealed that the a notable decline of ecological quality in areas characterized as good and excellent were observed during the implementation of phase 1 projects. Conversely, enhancement of the regional ecological environment by optimizing areas of moderate and good quality were observed during the implementation of phase 2 and 3 projects. 3) The frequency of agricultural land consolidation was positively correlated with the ecological quality of the respective project area. This indicated that an increase in consolidation efforts within the same region was associated with a more pronounced enhancement in ecological quality from 2000 to 2020. 4) Changes in the ecological quality of the agricultural land consolidation project area was resulted from the combined effects of natural and socioeconomic factors. The phase 1 projects were mainly driven by the interation of scale of project construction and the increase in cultivated land area, whereas the phase 2 and 3 projects were primarily influenced by the interaction between project type and elevation. The research outcomes enhance our understanding of alterations in ecological quality within areas designated for agricultural land consolidation projects. These findings serve as valuable references for agricultural land consolidation and ecological monitoring in hilly and mountainous regions.