基于景观连接度的土地整理生态效应评价

近年来,土地整理区的生物多样性保护和景观功能的维持受到广泛关注。本文选取贵州省道真县洛龙镇国家重点土地整理项目区,运用基于结构与功能相结合景观连接度模型(综合连接度(IIC)和连接度概率(PC)),计算了500、1000、2000、3000和4000m种群迁移扩散距离阈值情景下,土地整理前后各生境斑块对景观连接度的重要程度,识别重要斑块变化范围,从功能角度评价整理后的生态效应。结果表明:连接度指数能较好地识别土地整理前后各生境斑块的重要类别及其改变;其中,巨型斑块所占面积最大,分别占总面积的57.0%和57.2%;小型斑块数目整理前后分别占斑块总数的48.0%和48.9%;空间上,斑块的重要性分布也产生一定的变化。整理后生境斑块的连通性较整理前也有所下降,IIC和PC平均值分别为0.434和0.680,且随着距离阈值的增大,连接度逐渐增大。巨型斑块对生境斑块景观连通性的相对重要值最大,中型斑块和大型斑块次之,小型斑块最低。研究表明,土地整理过程中,大面积生境斑块和"踏脚石"斑块对维持土地整理生态效益具有重要作用。

Ecological effect of land consolidation: An assessment based on landscape connectivity

In recent years, the biodiversity conservation and landscape maintenance in land consolidation areas have received widespread concern. Taking the Luolong Town in Daozhen County of Guizhou Province, Southwest China as a case, this paper studied the ecological effect of land consolidation at landscape level, by using the landscape connectivity model (integral index of connectivity, IIC; and probability of connectivity, PC) to calculate the importance of habitat patches to landscape connectivity before and after land consolidation, to identify the change range of important patches, and to assess the ecological effect after land consolidation from a functional point of view under the background of 500, 1000, 2000, 3000, and 4000 m population dispersal potentials. It was observed that the connectivity indices could better identify the important types of all habitat patches and their changes before and after land consolidation. Giant patches had the largest area, occupying 57.0% and 57.2% of the total before and after land consolidation, respectively, while the number of small patches accounted for 48.0% and 48.9% of the total patch number before and after land consolidation, respectively. Spatially, the importance distribution of habitat patches also had some changes. As compared with that before land consolidation, the connectivity of habitat patches after land consolidation had somewhat decrease, the average values of IIC and PC were 0.434 and 0.680, respectively, and the connectivity of habitat patches increased gradually with the increase of distance threshold. Giant patches had the maximum relative importance value to the landscape connectivity of habitat patches, followed by medium and large patches, and small patches. It was suggested that during land consolidation, large area habitat patches and "stepping-stone" patches played important roles in maintaining the ecological effect of land consolidation.