时序遥感支持下宁波市耕地生态质量扭转过程及驱动力分析

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

监测耕地生态质量演变及其驱动因素响应过程,对于维护农业生态平衡和可持续发展具有重要意义.研究利用遥感时间序列连续变化检测和分类算法(CCDC)合成每年同一时期影像,规避了云雨天气和耕地物候波动影响.在此基础上,通过构建综合生态评估指数(CEEI)并辅以地理探测器,精确识别了宁波市耕地生态质量扭转过程及驱动机制.结果表明:(1)以2014年为拐点,宁波市耕地生态质量经历先缓慢下降后快速上升的扭转过程,CEEI均值由0.649降至0.617再升至0.628,2019年已恢复到2003年生态水平.各区县耕地生态质量在2011~2015年陆续出现拐点,北部(中心城区、余姚和慈溪)表现为先下降后恢复趋势,南部(宁海、象山和奉化)表现为先平稳后快速抬升趋势.(2)宁波市耕地生态质量主导驱动因素经历由农村劳动力资源数(1990~1994年)向灌溉面积/农村化肥施用量(1995~2014年)再向农村劳动力资源数(2015~2019年)的回转.近5 a农村劳动力回流以及农业机械化水平的提高保证了宁波市土地整治和高标准农田建设的快速推行,是耕地生态质量扭转的直接原因,这一作用在中心城区和慈溪尤为显著.研究可为沿海城市耕地质量精细监测提供技术参考,并为耕地资源高效管理、农业高质量发展提供决策支持.

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:①With 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.②The 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.