近10年来长江下游地区耕地动态变化特征

基于遥感资料和GIS分析,对1988～1998年长江下游地区耕地与其他土地利用类型之间相互转变数量特征,以及耕地变化强度、耕地流失强度的区域分异特征进行了分析和描述,对耕地变化导致的环境效应进行了初步探讨。研究结果表明:①1988～1998年,耕地与林地、灌丛、水体之间的转变,对其数量动态变化起着主要作用,在上述转变过程中,耕地总体表现出数量明显减少、质量降低的趋势;②农田向城镇的单向转移,体现了区域快速城市化对耕地的侵占过程,从空间分布看,该过程主要体现于上海、苏锡常地区、南京、杭州等城市化过程最为剧烈的地区;③长江下游地区1988～1998年耕地年均流失率为0.77%,流失的主体部分是位于长江三角洲和巢湖平原自然条件优越、水利灌溉配套设施完善的传统优质耕地,新形成的部分则主要来自于滩涂湿地开垦及低山丘陵地区毁林开荒。总体而言,长江下游地区耕地流失体现在数量锐减、质量下降两个方面,并伴随着一系列生态破坏问题的出现。

Dynamics and trends in cultivated land in lower Yangtze Valley in the past decade

Based on the multi-temporal remotely sensed data of TM,this research attempted to reveal the spatio-temporal trends in cultivated land in the lower Yangtze Valley by depicting and analyzing the intensity of cultivated land loss and transformation modes related to the cultivated landuse,the environmental impacts associated with cultivated landuse transformation were also discussed.The results showed that:1)The transformation between cultivated land and woodland,shrubs&water body acted as the main contributors to the changes in cultivated land,leading to remarkable reduction both in quantity and quality of the cultivated land in the lower Yangtze Valley from1988to1998,2)The transformation from cultivated land to the urban landuse reflected the rapid encroachment to farmland in the process of urbanization.This process is most obvious in the major urban areas of the Yangtze River Delta such as Shanghai,Suzhou-Wuxi-Changzhou District,Nanjing and Hangzhou,where urbanization is believed to be most intense nation wide in the past decade,3)The rate of cultivated land loss is0.77%,which mainly occurred in the Yangtze River Delta and Caohu Lake Basin where is dominated by the large area of high quality cultivated land well equipped with irrigation system.On the other hand,the newly developed cultivated land was observed mainly in coastal region and hilly area.In general,the resource dynamics of cultivated land in the lower Yangtze Valley in the past decade was dominated by the drastic decrease in quantity and the obvious decline in quality.A series of ecological problems were also highlighted in the process of landuse transformation related to the cultivated land.