基于图论的哈尼梯田区河渠网络关键节点和廊道评价

Evaluation of key nodes and corridors of river and canal network in Hani Rice Terraces based on graph theory

景观连接度作为测度生境景观生态过程和生态功能的重要指标,对区域内的生物迁移扩散、干扰扩散、基因流动等生态过程具有重要作用。本文利用2010年云南省元阳县的Quick Bird影像,以元阳县全福庄河小流域内的河流与沟渠廊道为研究对象,借助图论的方法,分别利用节点与廊道2种不同的计算单元,计算了500、1000、2000、4000和6000 m五个距离阈值下的景观连接度与重要性指数。通过直观展示哈尼梯田景观廊道的结构,分析其连接度与廊道的重要性指数,从而进行景观格局分析与规划。结果表明:连接度能在很大程度上指示区域内廊道的重要性,反映区域内廊道的连接情况;此外,随着阈值的增大,连接度逐渐增大。对重要性指数分析表明,在河网密集的地方,连接不同区块的廊道重要性指数较高,而在河网稀疏的地方,则较长的廊道发挥着更重要的作用。研究结果为哈尼梯田生态保护与规划提供思路,并为景观连接度的研究提供新的角度。

Landscape connectivity is an essential indicator for ecological processes and functions of habitat landscape, which plays an important role in the research of ecological processes such as biological migration and dispersal, interference diffusion, and gene flow. In this study, we used the Quickbird image of Yuanyang County, Yunnan Province in 2010 to study river and ditch cor- ridors in Quanfuzhuang watershed of Yuanyang County. By means of graph theory, two calculating units （node and corridor） were selected to calculate landscape connectivity and importance index with five distance thresholds of 500, 1000, 2000, 4000 and 6000 rn. With the graph of Hani ter- raced landscape corridor structure, the importance index of connectivity and corridor were ana- lyzed, with further analysis and planning of landscape pattern. The results showed that the degree of connectivity indicated the importance of corridors to a greater extent, and reflected their con- nection situations. Meanwhile, connectivity degree increased with the increase of threshold value. Besides, the analysis of importance index showed that the importance index was higher for the corridors connected with different blocks in intensive river network, while the importance index of the longer corridors was higher in sparse river network. The study provides ideas for the ecological conservation and tv research. planning of Hani Rice Terraces, and also new insights for landscape connectivi-