Dynamical monitoring of ecological environment quality of land consolidation based on multi-source remote sensing data

Abstract: Land consolidation is one of the important means to safeguard national food security, support rural revitalization strategy, optimize the allocation of land resources, and promote the construction of ecological civilization. Ecological transformation is the inevitable trend for the development of land consolidation. It is quite important to carry out scientific and reasonable, objective and direct, and long-term comprehensive monitoring and evaluation of ecological environmental quality at project area scale. Based on remote sensing technology, RSEI (remote sensing ecological index) model can quickly, objectively and quantitatively evaluate regional ecological environment quality, and realize visual representation, time-space analysis, simulation and prediction of regional ecological environment quality changes. Applying multi-source remote sensing data and taking 6 years before and after land consolidation as study period, this research constructed the RSEI model with principal component analysis, and retrieved values of the wetness, greenness, heat, and dryness indicators and RSEI index to monitor and analyze ecological environmental quality in a typical land consolidation project. The standard values in the research are: 1) RSEI ranges from 0 to 1, and the closer to 1 the value, the better the ecological environment quality. 2) The RSEI basic level is divided into 5 levels from small to large, i.e. "poor, inferior, medium, good, and excellent". 3) Based on the RSEI basic level, the RSEI level is divided into 9 subdivision levels (from (4 to 4) and 3 classes (worse, unchanged and better). All negative subdivision levels are classified as "worse", 0-value is classified as "unchanged", and all positive subdivision levels are classified as "better". The result shows: 1) The wetness and greenness indicators have a positive effect on promoting the ecological environment quality of the region, while the heat and dryness indicators have a restraining effect on the regional ecological environment quality, and the dryness indicator is more significant than the other 3 indicators. 2) Before, during, and after the land consolidation, the mean values of RSEI are 0.652, 0.572, and 0.605, respectively, and the proportion of excellent plus good RSEI class accounts for 78.73%, 39.55%, and 63.29% respectively in 3 periods. Meanwhile, the degenerated, unchanged, and improved RSEI classes are 42.55%, 46.25%, and 11.20% of the total area, respectively. 3) In this project area, the ecological environment quality presents a trend of decreasing firstly and increasing later, with an overall trend of decreasing, which are the characteristics of "turning worse during the consolidation period, getting better during the recovery period, and becoming worse in the overall process". Land consolidation causes persistent disturbance to the ecological environment, and there is a lag to restore and improve regional ecological environment. Five years after the project completion, the ecological environment quality level is still lower than before. The project area is the direct target of land consolidation and the carrier of benefit manifestation. This study can provide certain theoretical guidance and method reference for the continuous monitoring and dynamic assessment of ecological environment quality at the project area scale. Furthermore, it can provide certain method reference and data support to improve the local ecological environment, ensure the quality of cultivated land, improve agricultural production conditions, and promote regional sustainable development in some degree.