喀斯特地区贫困乡村景观格局及生态风险分析

为揭示喀斯特不同地貌乡村景观格局及生态风险的差异，以贵州省石门乡（喀斯特中山）、宗地镇（峰丛洼地）、周覃镇（低山丘陵）、掌布镇（峰丛峡谷）4种典型喀斯特地貌的贫困乡村为例，利用ArcGIS 10.1、Fragstats 4.2软件对乡村景观格局进行分析，并定量评价景观生态风险。结果表明，不同地貌乡镇的各斑块面积占比（PLAND）、斑块数量（NP）、斑块密度（PD）、斑块形状指数（LSI）存在较大差异。掌布镇景观水平上指标特征与石门乡相反，而宗地镇和周覃镇景观水平上指标特征介于掌布镇和石门乡之间。周覃镇与掌布镇景观生态风险低于石门乡以及宗地镇。石门乡中北部景观生态风险高于东部和西南部，与中北部以未利用地和建设用地景观为主、东部和西南部以灌草丛和林地景观为主有关。宗地镇中部比重较大的未利用地使其景观生态风险较高，而东部和西部比重较大的灌草丛使其景观生态风险较低。除西部地区外，周覃镇大部分地区耕地、林地和灌草丛的连片分布使得景观生态风险较低。中北部占主导地位的林地以及南部各地类的镶嵌分布，使掌布镇中北部景观生态风险明显低于南部。研究结果可为喀斯特地区乡村土地利用调控及生态风险管理提供科学依据。

Landscape pattern and ecological risk analysis of poor rural areas in karst regions

In order to demonstrate the distinctions of rural landscape and ecological risks in different karst land forms, an analysis of the landscape pattern was conducted using ArcGIS 10.1 and Fragstats 4.2 software. In addition, landscape ecological risk was assessed quantitatively using data collected from Shimen Town(mid-mountain karst), Zongdi Town(peak-cluster depression), Zhouqin Town(low hills), and Zhangbu Town(peak-cluster canyon). We found that the proportion of patch area(PLAND), number of patches(NP), patches density (PD), and landscape shape index(LSI) varied among towns. The landscape index characteristics of Zhangbu Town in a peak-cluster canyon contrasted with those of Shimen Town in a mid-mountain karst, while the landscape index characteristics of Zongdi Town in a peakcluster depression and of Zhouqin Town in low hills were intermediate between those of Zhangbu and Shimen Town. The landscape ecological risk for Zhouqin Town in low hills and for Zhangbu Town in a peak-cluster canyon was lower than that for Shimen Town in a mid-mountain region and for Zongdi Town in a peak-cluster depression. The landscape ecological risk for the north of Shimen Town was higher than that for the east and southwest regions because the northern region was dominated by undeveloped land and construction land, whereas the eastern and southwestern regions were dominated by brush/grass land, and woodland. In the center of Zongdi Town, undeveloped land resulted in increased landscape ecological risk, whereas brush/grass land with a large proportion in the east and west reduced the landscape ecological risk. The concentration of contiguous distribution of farmland, woodland, and brush/grass land in most parts of Zhouqin Town seemed to mitigate the landscape ecological risk, which were in lower landscape ecological risk with the western region as an exception. The landscape ecological risk posed to the middle and north of Zhangbu Town was significantly lower than in the south owing to the centration of woodland in central and northern areas as well as the mosaic distribution of each type of land use in the south. The study provide a scientific basis for land use control and ecological risk management for rural karst areas.