土地整理对项目区生境景观连接度的影响

Effect of Land Consolidation on the Habitat Connectivity in the Project Area

生境景观连接度是反映生物多样性保护和景观功能的重要指标之一,利用景观连接度方法可将生物个体和种群的扩散距离和行为反应纳入土地整理效应分析之中。本文基于景观连接度理论方法,以竹镇镇重点土地整理项目区双龙村为研究区,利用GIS平台和Conefor26软件,选择反映不同物种空间扩散能力的10个景观距离阈值,探讨了土地整理项目区整理前后不同景观阈值下连接度的变化,并尝试在剔除沟渠的情况下,分析土地整理前后,景观结构与功能的变化。在此基础上分析了整理前后各生境斑块对景观连接度的重要程度,识别重要斑块变化规模与空间范围,从功能角度评价整理后的生态效应。结果表明:整理后的IIC和PC值分别比整理前平均降低了45.58%、39.03%,因此土地整理对当地景观连接度造成了不利影响;土地整理形成的人工沟渠网络在较低距离阈值范围内对景观的连接起着重要作用;巨型斑块对生境斑块景观连通性的贡献大且稳定;基于图论的连接度分析法,能同时体现景观的结构连接度及功能连接度,还能较好反映景观破碎化、识别垫脚石斑块。该方法不仅能用于测度土地整理的生态效应,还可为土地整理项目区的生态用地结构、布局等提供理论参考。

Habitat landscape connectivity is one of important index for measuring biodiversity conservation and landscape function sustainability. The landscape connectivity approach based on graph theory used in land consolidation effect analysis is able to take organism individual and its behavior into consideration. In this paper, we take a land consolidation project area,where is located in Shuanglong village, Zhuzhen town of Nanjing, as a study area. The GIS and Conefor 26 software are employed to calculate the landscape connectivity metrics and patch important value. Ten distance thresholds including 10 m,50 m, 100 m, 200 m, 500 m, 700 m, 1000 m, 1500 m, 2000 m, 3000 m that reflecting the spatial diffuse capability of different species were selected for analyzing the habitat landscape connectivity change before and after land consolidation respectively.The situation of with and without ditches before and after land consolidation was considered as well to compare the landscape structure and function changes. Then we test the contribution of each habitat patch to landscape connectivity and identify the variation range and spatial scope of important habitat patch due to land consolidation project. The results show：（1） Integrated index of connectivity（IIC） and probability connectivity（PC） index were decreasing by 45.58% and 39.03%for land consolidation. And the consolidation shows a negative impact on habitat connectivity.（2） The increasing ditch network due to the consolidation can improve the connectivity at lower distance threshold range.（3） The habitat patch with larger area size will always contribute a lot to connectivity.（4） The connectivity approach based on graph theory can used to measure landscape structure connectivity and function connectivity,and to test landscape fragmentation and identify the stepping stones for species. Therefore the approach is good for ecological effect evaluation for land consolidation, and can provide a guide for planning the composition and configuration of habitat or ecological land in a land consolidation project area.