基于退耕还草背景的科尔沁沙地土地利用景观格局分析

以2000、2005年的土地利用矢量数据为基础数据,选用生态意义较明确的景观特征指数,从区域和旗县2个尺度,定量分析了科尔沁沙地实施退耕还草工程5年间土地利用景观格局的变化态势,并揭示了土地利用景观格局变化对区域生态环境的影响。结果表明:⑴退耕还草5年间,科尔沁沙地的水田、旱地、有林地、灌木林地、疏林地和高覆盖度草地景观的面积及空间分布的连续性趋于增大,而沙地、盐碱地、水域及沼泽湿地景观的面积及空间分布的连续性趋于减小;各旗县景观斑块类型的变化趋势不尽相同。⑵退耕还草5年间,科尔沁沙地的景观多样性降低0.97%,景观优势度增大3.08%,景观破碎化程度降低2.00%,整体景观组成趋于简单;各旗县景观结构的变化趋势不尽相同。⑶退耕还草5年间,科尔沁沙地旱地面积变化率与生态环境指数变化率间呈显著负相关(P=0.008,r=0.674,n=14),而高覆盖度草地面积变化率与生态环境指数变化率间呈显著正相关(P<0.001,r=0.876,n=14),表明科尔沁沙地实施退耕还草工程期间,风蚀严重的旱地的退耕和高质量草地的建植是提高区域生态环境质量的关键。

Analysis on landscape pattern of land-use in Horqin Sandy Land on the background of conversion of cultivated land to grassland

Based on the sketch date of the land use in 2000 and 2005,using the more explicit landscape metrics we quantified and analyzed the change situation of the landscape spatial pattern in Horqin Sandy Land from regions and banners,after the conversion of cultivated land to grassland project has been carried out for five years.The research also reflected the effect of landscape pattern on regional ecological environment.The results showed:(1) During the five years,the area and continuity of spatial distribution of paddy field,dry land,forest land,shrub land,open forest land,high coverage grassland landscape tended to increase.While the area and continuity of spatial distribution of sand,alkaline land,water area,swamp and wet land landscape tended to decrease.The change trend of the landscape patch types in every banner(country) was different.(2) During the five years,the landscape structure in Horqin Sandy Land had changed in several aspects.The diversity index of landscape decreased by 0.97%.The dominance index of landscape increased 3.08%.The fragmentation index of landscape reduced by 2.00%.The overall landscape composition trended to be simplified.The change trend of landscape structure in every banner(country) was different.(3) Correlative analysis showed there was a remarkable negative correlation of change rate between the area of sand landscape and ecological environment index in Horqin Sandy Land(p=0.008,r=0.674,n=14),while there was remarkable positive correlation of change rate between the area of high coverage grassland landscape and the ecological environment index(P<0.001,r=0.876,n=14).It showed that how to covert the dry land to grassland and plant the high quality grassland is the key problem of the conversion of cultivated land to grassland project in Horqin Sandy Land.