扎龙湿地景观动态变化特征

扎龙湿地近35年来湿地景观发生了巨大的变化,本文定义了一套基于TM影像的适用于描述湿地景观变化的湿地分类系统,利用景观转换系数分析以5年为周期的时间尺度上湿地的转换幅度的变化,统计和分析了湿地从1979-2013期间景观转换系数的动态变化特征,总结了扎龙湿地景观动态变化主要为四类景观动态类型：A-小幅度规则型稳定景观,B-中幅度不规则型变化景观,C-幅度渐弱规则型稳定景观,D-大幅度不规则型变化景观。研究表明：扎龙湿地1979-2013年期间,湿地景观在前10年向湿生景观转换,但是转换的幅度越来越小;后20年,湿地转向干旱趋势。在不同的景观动态类型中A类小幅度规则型稳定景观所占面积最大,为973.60 km²,接近湿地面积的二分之一,主要集中在核心区和外围稳定的农田部分;D类大幅度不规则型变化景观面积最少,为311.92 km²,主要分布于人类干扰强烈的区域。

Characteristics of landscape dynamic changes in Zhalong Wetland

As an internationally well known and ecological zone, Zhalong Wetland has undergone tremendous landscape changes based on hydrological pattern in recent decades. We defined a set of wetland classification system to describe the landscape changes by using Landsat TM images during 1979-2013, and analyzed the changes of landscape transition magnitude by landscape transition coefficient on a 5-year time scale. Four types of landscape dynamics were identified at Zhalong Wetland: stable landscape with regular and little magnitude, unstable landscape with irregular and normal magnitude; stable landscape with degraded and regular magnitude; unstable landscape with irregular and huge magnitude. The results show that: wetland landscape tended to be wet before 1989 with smaller magnitude, and tended to dry after 1989. In terms of dynamics, the area of A landscape （973.60 km²） is mainly distributed in the core area and farmland; the area of D landscape （311.92 km²） is mainly in the sites of human disturbance, such as on both sides of large ditches and dams.