三江平原别拉洪河流域湿地农田化过程中湿地-农田景观梯度时空特征分析

湿地农田化过程是三江平原过去50年以来土地覆盖变化的主要特征,由于大面积的湿地被农田所替代,原有的自然生态环境遭到了严重破坏。本文选取三江平原别拉洪河流域作为研究对象,基于RS和G IS技术,集成地形图与遥感数据(MSS,TM,CBERS),利用景观梯度分布分析模型,对1954~2005年期间湿地与农田景观梯度时空变化特征进行了分析。结果表明,1954年除西南部靠近松花江地区、浓江上游地区湿地景观分布较为稀疏外,其他地区都属高湿地景观梯度区。到2005年,除洪河自然保护区及靠近黑龙江和乌苏里江边缘地区外,研究区的大部分都成为耕地景观高梯度分布区。耕地景观和湿地景观梯度分布格局的变化揭示了研究区湿地农田化过程的空间规律性,即耕地逐年向东扩展的同时,湿地相应地向东北方向消退。

Spatial and Temporal Analysis of Wetland and Cropland Landscape Gradient in Process of Conversion from Wetland into Cropland (CWC) in Bielahong Basin of Sanjiang Plain

The process of conversion from wetland into cropland(CWC) is the main feature of land cover change in Sanjiang plain in the past 50 years.Natural eco-environment has been destroyed seriously because lots of wetland was substituted by cropland.This paper analyzed spatial-temporal characteristics of landscape gradient of wetland and cropland based on RS and GIS,during 1954~2005 period, taking Bielahong basin as case study area.Data using in this paper was acquired with topographical data and remote sensing data such as Landsat MSS,Landsat TM,CBERS.Results showed that,in 1954,most of the study area was with high wetland landscape gradient.Only the area in southwest part nearing Songhua River and area in upriver zone of Nongjiang River were covered by dense wetland.However,in 2005,most of the study area was covered by cropland.In study area,changes of spatial distribution cropland landscape and wetland landscape revealed spatial laws of conversion from wetland into cropland.This phenomenon can be summarized as the enlargement of croplands towards east and the shrinkage of wetlands towards northeast.