Process of Land Conversion from Marsh into Cropland in the Sanjiang Plain during 1954-2005
Process of Land Conversion from Marsh into Cropland in the Sanjiang Plain during 1954-2005
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发表时间：
2009
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通讯作者：
W. Zong
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作者：
W. Zong
三江平原作为主要农业基地之一,也是大面积淡水沼泽分布的地区,对保障国家粮食安全和区域生态安全具有重要作用。由于人类活动的频繁,1954-2005年间大面积沼泽被耕地取代。此外,该地区还存在上述土地利用变化带来的诸多环境问题。有关研究未能揭示区域土地由沼泽转为耕地的过程和规律。基于遥感结合地形图和遥感数据,结合地形图和遥感数据,对1954-2005年土地由沼泽转为耕地的过程和驱动因素进行了分析。结果表明:1954-2005年,沼泽面积减少了3/4以上,从352.59×104 ha减少到95.87×104 ha,而耕地则增加了2.3土地面积由1954年的171.34×104 ha增加到2005年的556.88×104 ha。2005年,耕地占土地总面积的51.17%,成为三江平原的主导景观。1954-1976年和1977-1986年是土地沼泽转耕的两个阶段。这两个时期，土地转化面积分别为186.40×104 ha和120.30×104 ha。到2005年，土地转化过程基本结束。大片沼泽地仅分布在一些大型湿地自然保护区。1954-2005年，沼泽地转化为耕地的面积为258.48×104 ha， 1954年沼泽面积占沼泽面积的73.3%。与沼泽还耕地相关的主要自然环境特征是海拔0-100 m、坡度0°-1°的位置、河流缓冲区、河流阶地、沼泽低地和低阶地貌、草甸土、沼泽土和白化土等。近50年三江平原年平均气温增幅明显，增幅为0.029℃/a。气候变暖为农业开垦（特别是水稻种植）提供了有利的前提条件。区域大规模人口增长是沼泽还田最重要、最直接的驱动力。近几十年来，三江平原总人口增长了3.13倍。统计耕地面积与总人口和农业人口呈良好的线性关系。国家政策对沼泽还田的影响较大。很大程度上覆盖了三江平原。
The Sanjiang Plain,as one of main agricultural bases and the region distributing large-area freshwater marsh,plays an important role in safeguarding national food safety and regional ecological safety.Due to intensive human activities,large area marsh has been substituted by cropland during 1954-2005.In addition,There are many environmental problems resulted from land use changes above mentioned in the area.Researches concerning could not discover the process and rules of regional land conversion from marsh into cropland.Based on remote sensing and geographic information system technology,in this paper topographic maps and remotely sensed data were integrated,and the process and driving factors of land conversion from marsh into cropland were analyzed during 1954-2005.Results showed that,from 1954 to 2005,marsh area decreased by more than 3/4,from 352.59×104 ha to 95.87×104 ha.In contrast,cropland increased by 2.3 times,from 171.34×104 ha in 1954 to 556.88×104 ha in 2005.In 2005,cropland occupied 51.17% of the total land area,and became the dominant landscape of the Sanjiang Plain.The period 1954-1976 and the period 1977-1986 were the two stages in which land conversion from marsh into cropland happened with the largest scales.In these two periods,land conversion area is 186.40×104 ha and 120.30×104 ha,respectively.By 2005,the land conversion process ended basically.Large patches of marsh only distributed in some big wetland nature reserves.During 1954-2005,the land conversion area from marsh into cropland is 258.48×104 ha,and is 73.3% of marsh area in 1954.The main natural environmental features in relation to land conversion from marsh into cropland are those positions with elevation of 0-100 m,slope gradient of 0°-1°,physiognomies of river buffering area,river terrace,marsh low lands and low terraces,soils of meadow soil,marsh soil and bleaching soil.In the past 50 years,annual average air temperature of the Sanjiang Plain increased obviously,with an increasing rate of 0.029 ℃/a.Climate warming supplied favorable premise conditions for agricultural reclamation(especially the rice planting).Regional large-scale population increasing was the most important and direct driving force resulting in land conversion from marsh into cropland.In the past decades,total population of the Sanjiang Plain increased by 3.13 times.Statistical cropland areas had good linear relationships with total population and agricultural population.National policy impacted the land conversion from marsh into cropland of Sanjiang Plain to a big extent.