四川省茂县大沟流域42年植被景观格局恢复动态及其特征

Forty⁃two⁃year dynamics of vegetation landscape restoration pattern and its characteristics in Dagou basin,Maoxian County,Sichuan Province

中国西南亚高山地区的植被景观恢复动态一直缺乏深入研究,以四川省茂县的大沟流域为研究对象,基于航片、地面调查、QuickBird和Pleiades遥感影像数据源,采用人工目视解译的方法,建立了大沟流域景观格局分布信息数据库,开展了大沟流域1978—2020年景观格局恢复动态及其特征的研究。结果表明:(1)研究期间,流域内的优势景观为落叶杂灌、草地和油松林,由于封山育林政策的实施,在未来较长的一段时间内优势景观类型将得以保持。(2)1978—2020年间大沟流域的植被覆盖度维持在较高水平,森林面积逐渐增加,农业主要转变为果园经济,整体景观的动态度在逐渐减小。(3)随着植被的恢复,大沟流域景观的物种丰富度、优势景观优势度和景观的连通性都在增加,但景观的破碎化程度依旧较高。首次对大沟流域的植被演变进行了探究,为西南亚高山及岷江流域地区的森林恢复提供了一定的科学依据。未来相关领域还需加强景观格局演变驱动机制的研究,并制定更加合理的生态环境管理政策。

There has been a lack of in⁃depth research on the restoration dynamics of vegetation landscapes in the subalpine areas of Southwest China.This paper is based on the Dagou basin in Maoxian County,Sichuan Province as the research place.Our project established a database of information on the distribution of landscape patterns in the Dagou basin based on aerial photographs,ground surveys,QuickBird and Pleiades remote sensing imagery data sources,and the method of manual visual interpretation.The research methodology of this study includes landscape transfer matrix analysis(land use type transfer in 4 time periods:1978—1988,1988—2006,2006—2020,and 1978—2020.);Landscape dynamics analysis(including annual dynamics of a single landscape type and annual dynamics of the basin as a whole.)and landscape index analysis(including 3 dimensions of patch composition,patch shape complexity and degree of fragmentation,and connectivity,with a total of 7 landscape indices.).The results of the study showed that(1)the dominant landscapes in the basin during the study period were deciduous mixed shrubs,grasslands,and Pinus tabulaeformis forests,and the dominant landscape types will be maintained for a longer period in the future due to the implementation of the policy of forestation of closed mountains.(2)from 1978 to 2020,the vegetation cover of the Dagou basin was maintained at a high level,the forest area gradually increased,the agriculture was mainly transformed into an orchard economy,and the dynamic attitude of the overall landscape was gradually decreasing.(3)With the restoration of vegetation,the species richness,dominant landscape dominance,and landscape connectivity of the landscape in the Dagou basin increased,but the degree of landscape fragmentation remained high.In addition,this paper also discusses the characteristics and influencing factors of landscape pattern changes.The area above 2500m elevation in the Dagou basin is less affected by human activities and is dominated by natural succession.During the 42 years,the change in the area above 2500m elevation was small,and the transformation between grassland and shrubs was the main form of landscape change.The forestry policy has a greater influence on the landscape structure of the area below 2500m elevation in the Dagou basin,mainly affecting the forestry and agricultural landscape structure.This study is the first to explore the vegetation evolution in the Dagou basin,which provides a certain scientific basis for forest restoration in the subalpine and Minjiang River basin areas of Southwest China.In the future,related fields need to strengthen the research on the driving mechanism of landscape pattern evolution and formulate more rational ecological environment management policies.