Analysis Of Landscape Ecological Changes And Driving Forces In The Zari Namco Basin In Tibet In The Past Two Decades

The Zari namco lake in ali region of Tibet is an important alpine lake on the qinghai-tibet plateau.The main rivers into the lake are cuoqin zangbu and dalong zangbu.It is of practical significance for the healthy development of regional economy to fully understand the landscape ecological status of the lake basin and rationally develop and utilize natural environmental resources while protecting the local ecological environment.Based on the theory and method of landscape ecology,this paper makes a quantitative study on the changes and driving forces of landscape ecology in the past 20 years in the basin of Zari namco,probes into the causes of its ecological problems,and proposes reasonable human activities and lake basin protection measures.It provides a strong scientific opinion for the future resource and environment development,ecological environment construction,regional economic development,especially the development related to animal husbandry,etc.,and provides a scientific reference for the landscape ecological change research in other similar regions.In this paper,the study area in 2003 Landsat TM and ETM + 2008,Landsat7 ETM + in 2013 and 2018 Landsat8 OLI 4 remote sensing image data as the foundation,with the aid of the ARCGIS,ENVI software,such as the study area was constructed Zari namco basin is within the scope of the landscape database including landscape patch type,distribution,combination,etc.,and draw the area in 2003,2008,2013 and 2018,the study area landscape type distribution diagram.Main selection including type patch area,patch number,patch scale,largest patch index,landscape shape index,average patch size,concentration,patch density,landscape contagion index,shannon diversity index and shannon evenness index the landscape index,based on the use of Excel and FRAGSTATS 4.2 software to calculate the landscape pattern index;According to the statistics bureau of the Tibet autonomous region,the statistics bureau of cuoqin county,the agriculture and pastoral bureau of cuoqin county,the tourism bureau of cuoqin county and other relevant departments,the natural and cultural data from 2003 to 2018,such as statistical yearbook,statistical bulletin and government conference report,were provided to analyze the driving forces of landscape ecological change in the research area.This paper analyzes the landscape ecological changes in the river basin in Zari namco and draws the following conclusions:(1)During the period from 2003 to 2018,the landscape type composition and spatial distribution pattern of Zari namco watershed changed significantly.During the study period,the landscape type occupied the largest area of low-coverage grassland,followed by medium-coverage grassland and bare land.The number of patches in high-coverage grassland increased the most obviously and the most.The area of glaciers continues to shrink.During the period from 2003 to 2018,while the landscape area of the lake was continuously expanding,the glacier area was continuously shrinking and the area of medium coverage grassland showed a trend of fluctuation and decline.In addition,the landscape area of bare land,low coverage grassland,high coverage grassland and saline-alkali land all showed a trend of fluctuation and increase.(2)In the study area of landscape index analysis,the diversity,evenness and heterogeneity of landscape were reduced.The landscape spreading degree and fragmentation degree increased,and social and economic factors had a greater impact on the landscape ecological change in the region.For the whole basin,shannon diversity index showed an upward trend from 2003 to 2008,a downward trend from 2008 to 2013,and a re-upward trend from 2013 to 2018.The maximum value of shannon diversity index and shannon evenness index both appeared in 2008,while the minimum value appeared in 2013,showing the same trend.The maximum value of shannon diversity index and shannon evenness index both appeared in 2008,while the minimum value appeared in 2013,showing the same trend.The best period of landscape diversity in the study period was 2013,while the weaker period was 2008.In 2008,the fragmentation of the landscape was the highest,followed by 2003.From 2003 to 2018,the patch shape index of landscape level in the whole basin of Zari namco also showed a continuous rising trend.(3)Through correlation analysis and principal component analysis,this paper makes a qualitative and quantitative analysis on the natural factors and social and economic factors of landscape dynamic changes in the Zari namco basin from 2003 to 2018,and considers that social economy and population are the main driving forces for landscape pattern changes.With the economic development and population expansion in recent years,the residential land and construction in the research area are bound to expand,and the over-development of local natural environment,especially grassland resources,keeps increasing.The pressure of grassland resources in the research area increases,the grazing capacity decreases,the contradiction between human and land intensifies,the destruction of resources intensifies,and the diversity and integrity of the ecosystem is destroyed.Natural factors such as temperature,precipitation and evaporation also affect the distribution and variation of landscape patch types.