三江平原建三江地区30年湿地景观退化评价

因高强度农业开发,1975～2004年的30a间,三江平原自然湿地景观发生了剧变.评估该湿地景观面临的各种压力、分析其所处状态、揭示其演变规律,对于三江平原的湿地保护和恢复至关重要.选取1975年、1989年和2004年的三期Landsat TM遥感影像,基于压力-状态-响应的生态评价框架,对黑龙江省建三江地区景观演变进行分析.结果表明,(1)从1975年到2004年,建三江地区自然湿地大幅减少,农田大幅增加,景观多样性和破碎度显著提高;农业开发是自然湿地面临的主要压力,其中草甸和沼泽湿地是主要的开发对象.(2) 1975～1989年的农业开发强度高于1989～2004年.1975～1989年,农田、沟渠面积大幅增加,湿地面积大量减少;通过沟渠排水将湿地开发为旱田,导致该区生态环境质量下降,洪涝灾害频繁;1989～2004年,人们意识到湿地保护的重要性,自然湿地开垦减少,沟渠面积略有增加,并把部分旱田转为水田来达到"以稻治涝"的目的;同时,建立了多个湿地自然保护区并制定了相应的湿地保护条例,使得该区的湿地景观得到了一定的保护.(3) 当前三江平原湿地景观面临的问题依然严峻,尤其是排水沟渠的大量存在和旱田转化为水田后导致的水资源短缺和地下水位下降等问题,还将继续威胁现有湿地的存续,基于沟渠系统的综合性水资源管理势在必行.

Landscape assessment on wetland degradation during thirty years in Jiansanjiang region of Sanjiang Plain, Northeast China

The natural wetland landscape was seriously degraded in thirty years (1975-2004), because of the high-intensity agricultural exploitation in Sanjiang Plain. It is very important to conduct landscape assessment for wetland preservation and restoration in the region in terms of the various pressures to, and the present state and change of the wetland. By choosing Landsat TM remote sensing data of the years 1975, 1989 and 2004, the landscape change of Jiansanjiang region of Heilongjiang Province was analyzed on the basis of Presure-State-Response ecological assessment framework. The results showed that, (1) From 1975 to 2004, the natural wetland was greatly decreased while farmland obviously increased, and landscape diversity and fragmentation were remarkably increased; Agricultural exploitation was the main pressure the wetland faced during the period, where wet meadow and swamp were the main targets of the exploitation. (2) The agricultural exploitation in 1975-1989 was much higher than that in 1989-2004. From 1975 to 1989, the areas of farmland and drainage ditch were abruptly increased while that of wetland was greatly decreased, that is, the wetland was mainly converted into farmland through the discharge of drainage ditch system, which led to the decline of ecological and environmental quality, especially the frequently happened flooding, in the region. However, from 1989 to 2004, wetland preservation was recognized important, the exploitation on natural wetland was limited and the drainage ditch was slightly increased, moreover farmland was partially converted into paddy field so that to preventing flooding. Meanwhile, some wetland nature reserves were established during the period alongside the establishing of some wetland conservation regulations, the wetland landscape was then preserved to a certain extent. (3) The problems that Sanjiang Plain wetland landscape facing are still serious at present, especially the shortage of regional water resources and the declining of underground water level because of the existence of drainage ditch system and the conversion of farmland to paddy field, which will continuously threaten the survival of current wetlands, therefore it is urgent to synthetically manage regional water resources on the basis of drainage ditch system.