1954-2015年不同地貌分区下湿地农田化过程的时空特征——以完达山以北三江平原为例

摘要

The Sanjiang Plain north of the Wanda Mountains,or the sub-Sanjiang Plain for short,was selected as the study area and sampled with a typical transect using the principle of transect selection.The spatiotemporal characteristics of wetland to farmland conversion processes were explored using time series of land use/land cover datasets for the different geomorphological divisions.The specific conclusions of this study include the following:1) The area of farmland in the subSanjiang Plain increased significantly,with the reclamation rate reaching 79.47％.The farmland structure also changed significantly,from being dominated by croplands to being dominated by paddy fields,between 1954 and 2015.2) The process of wetland to farmland conversion in the sub-Sanjiang Plain occurred in clear historical stages,with wetland conversion progressing slowly from 1954 to 1976,and increasing more rapidly during the periods of 1976-1985 and 1985-1995.Conversion of wetlands was most severe from 1995 to 2005,but has slowed in the most recent decade.3) The process of wetland to farmland conversion was influenced by the regional geomorphic types.Wetland reclamation first appeared in the Meco-scale Quaternary Slow Ascent region,and then extended to the Substantially Quaternary Slow Subsidence and Small-amplitude Quaternary Slow Ascent regions.4) The process of wetland reclamation showed clear features related to the geomorphological divisions,beginning in the alluvial plain and low terrace,extending to the high floodplain,and then continuing into the low floodplain and depression.%以完达山以北三江平原(以下简称为小三江平原)为研究区,依据样带选择原则选取具有湿地农田化典型性的区域(即典型样带).在地质地貌分区的基础上,基于特定历史时期的土地利用/覆被数据集构建长时间序列的耕地和沼泽湿地动态变化数据集,利用RS和GIS技术分析小三江平原典型样带内湿地农田化的时空变化规律,探究近60年小三江平原内湿地农田化的区位特征,结果表明:(1) 1954-2015年,小三江平原的耕地面积显著增加,垦殖率达到了79.47％,耕地结构发生了显著的变化;(2)小三江平原湿地农田化具有明显的历史阶段性:在改革开放之前(1954-1976年)湿地农田化程度不是很大,改革开放初期(1976-1985年)开始发生明显的湿地农田化,到全面改革开放期(1985-1995年)湿地农田化程度加重,在改革开放转型期(1995-2005年)湿地农田化最严重,在深化改革开放期(2005-2015年)湿地农田化程度有所减小;(3)区域大的自然背景决定了小三江平原湿地农田化整体趋势:1954-2015年间,小三江平原湿地农田化最初发生在中幅度沉降第四纪缓慢上升区,逐步扩展到大幅度沉降第四纪缓慢沉降区和小幅度沉降第四纪缓慢上升区;(4)小三江平原湿地农田化具有明显的地貌区位特征:湿地农田化最初发生在冲积平原上,然后扩展到河流低阶地和高河漫滩上,随着时间的推移逐步扩展到低河漫滩和微高地上,最后蔓延到洼地上.