[Reversal Process and Driving Force Analysis for Arable Land Ecological Quality in Ningbo Using Time-series Remote Sensing Technology].

Timely monitoring of the changes in the ecological quality of arable land and the driving forces is of great significance for maintaining the ecological balance and sustainable development of agriculture. This study used the advanced time-series remote sensing continuous change detection and classification （CCDC） algorithm to synthesize images with the acquisition date of each year, in order to overcome the impacts of cloudy weather and vegetation phenology. Based on this, the reversal process and mechanism for the ecological quality of arable land in Ningbo were precisely identified using the comprehensive ecological evaluation index （CEEI） and geo-detector methods. The results showed that：① With a key turning point of the year 2014, the ecological quality of the arable land in Ningbo experienced a rapid rebound after a long-term decline, represented by the average CEEI decreasing from 0.649 to 0.617 and rising to 0.628. Until 2019, the ecological quality had recovered to the level of that in 2003. This reverse in the ecological quality of the arable land for each district successively appeared from 2011 to 2015, the northern area of Ningbo （i.e., the town center, Yuyao, and Cixi） presented a restored trend after first degraded, while the southern Ningbo area （i.e., Fenghua, Ninghai, and Xiangshan） presented an improved trend after long-term maintenance. ② The dominant driving force of the ecological quality of the arable land in Ningbo presented a reversal that it first converted from the rural labor resource （the period： 1990-1994） to the irrigated area or rural fertilizer usage （the period： 1995-2014） and then converted to the rural labor resource （the period： 2015-2019） again. The maintenance of the rural labor resource and the improvement in the level of agricultural mechanization in the past 5 years facilitated the implementation of land consolidation and high-standard farmland development, which directly promoted the reversal process. Such fundamental and key effects of the rural labor resource were particularly outstanding for the town center and Cixi. The study can provide technical reference for accurate monitoring of the ecological quality for coastal cities, and the related findings are expected to serve for the effective management of arable land resources and high-quality development of agriculture.