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基于GIS的雅鲁藏布大峡谷景观格局与生态敏感性分析

Analysis of Landscape Pattern and Ecological Sensitivity of Yarlung Zangbo Grand Canyon Based on GIS

  • 摘要: 针对近期高寒山区生态景观急剧变化、严重影响生态敏感性的问题,为了更好地评价和分析这种变化带来的一系列生态现象,选取大峡谷为研究区,利用面向对象的分类方法确定景观类型,以多样性指数、优势度指数、均匀度指数和聚合度指数等作为指标,对研究区的生态敏感性进行评价和分析。采用面向对象的分类方法最终得到10类景观类型的斑块共1 761个,其中林地景观和草地景观的面积占比最大,分别为48.84%和22.68%,冰雪/冰川景观的占比为17.39%。从景观指数来看,研究区景观多样性指数为1.374,优势度指数为0.982,均匀度指数为0.597,聚合度指数为97.374。可以看出,大峡谷研究区拥有较高的多样性,单一景观优势度相对较低,不同景观空间分配情况更好,总体上该区域景观以原始森林、高山草甸和冰川为主,人类活动干扰较小,并主要集中在河谷地带农田和草地的转换中。综合6类影响因子对大峡谷研究区生态敏感性进行加权分析,生态敏感性主要集中在中度和高度敏感区域,占比合计95.71%。中度敏感区域集中分布于河谷周边低海拔、低坡度区域,以水域、草地、灌木林为主;高度敏感区域集中分布于山地高海拔区域,以林地景观、冰雪/冰川景观为主。

     

    Abstract: Due to human over-exploitation and utilization in recent years,the landscape types of Tibet’s alpine mountains have been severely damaged. The landscape pattern index can effectively evaluate the evolution of landscape types on the time scale. Therefore,an object-oriented classification method was used to determine landscape types,and the diversity index,dominance index,uniformity index and aggregation index were selected as indicators to evaluate and analyze the ecological sensitivity of the study area. The grand canyon was selected as the study area,and the object-oriented classification method was used to algorithmically classify the Tibetan artificial disturbance zone. Finally,a total of 1 761 patches of ten types of landscapes were obtained,of which the woodland landscape and grassland landscape with the largest areas,respectively were 48. 84% and 22. 68%,and the proportion of snow/glacier landscape was17. 39%. From the landscape index,the landscape diversity index in the study area was 1. 374,the dominance index 0. 982,the evenness index 0. 597,and the polymerization index 97. 374. The grand canyon research area had high diversity,the single landscape had a relatively low dominance,and the distribution of different landscape spaces was better. In general,the landscape in this area was dominated by virgin forests,alpine meadows and glaciers,with less disturbance of human activities,and was mainly concentrated in the conversion of farmland and grasslands in the valley. Based on the weighted analysis of the ecological sensitivity of the grand canyon study area,the six types of impact factors were combined.The ecological sensitivity was mainly concentrated in moderate and highly sensitive areas,with a total of95. 71%. Moderately sensitive areas were concentrated in low-altitude and low-slope areas around river valleys,and the land was mainly waters,grasslands and shrubs. Highly sensitive areas were concentrated in high-altitude areas of the mountains,with steep slopes. The landscape was dominated by woodland landscapes and glaciers/ice landscapes.

     

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