| China is a big mountain country,and mountainous area is an important part of the whole ecosystem of the earth.It is the birthplace of large rivers and is the main source of mineral resources and water resources in China.It regulates regional climate,improves ecological environment,enhances species diversity,water conservation.It have important ecological service function value.China's mountain resources are mainly located in the transition zone between the two major geomorphic units in the southwestern Qinghai-Tibet Plateau to the Sichuan Basin.This area is the ecological and functional area of Sichuan-Yunnan forest and biodiversity and soil and water conservation.It is an important ecological barrier and water source conservation area in the upper reaches of the Yangtze River Yellow River.The southwest mountainous area of China is located in the Mediterranean-Himalayan seismic zone.The geographical environment is special,the terrain is undulating,and the geological tectonic movement is active.In the past ten years,three earthquakes of magnitude 7.0 above have occurred,which are mountainous areas with strong earthquakes.Under the induced factors such as earthquakes and rainfall,the area has become a concentrated area of geological disasters such as mountain torrents,collapses,landslides and mudslides,and the ecological environment is fragile.Because the mountain ecological environment system has weak resistance and resilience to natural and human disturbance behaviors,with the gradual development of regional social economy,the pressure of the region as a key constraint between ecological environmental protection and regional economic development is becoming increasingly prominent.Landscape is the main carrier of human social and economic activities.The landscape pattern determines the distribution of environmental resources.Therefore,scientific understanding of the dynamic changes in the landscape of strong earthquakes and the spatiotemporal process of landscape pattern vulnerability are of great significance for post-disaster reconstruction,protection and construction in mountainous areas.Although the current theories and methods for the protection and construction of ecological barriers in the fragile zone of the strong earthquake mountain area have been studied and explored,research on the natural and human interactions in the strong earthquakes based on landscape ecology is still lacking.This paper relies on the National Natural Science Foundation of China project “Spatial and Environmental Impact Carrying Capacity Analysis and Early Warning of Grassland Pastoral Areas—Taking Jianghe Source Area in Northwest Sichuan as an Example(41401659)”,taking Jiuzhaigou County as a research case area,the quantitative study on the spatiotemporal process and driving force of the landscape pattern vulnerability in strong earthquake mountainous areas has been carried out.This study uses “3S” technology to acquire data and mine landscape type information.Based on the landscape pattern index,quantitative analysis the spatial and temporal changes of landscape types and patterns in strong earthquake mountainous areas.Based on the landscape pattern vulnerability index evaluation model,the characteristics of the spatiotemporal process of the landscape pattern fragility in the strong earthquake mountain area are grasped.The main driving forces for spatial clustering of different landscape patterns in strong earthquake-stricken areas are discussed,which provides technical support and reference for natural resource management protection and land landscape pattern optimization.The main research results obtained in this paper are as follows:(1)During the study period,the area of cultivated land continued to decrease,the area of construction land continued to increase,and the contradiction between cultivated land protection and economic development and construction became increasingly prominent.Between 2002 and 2012,the area of grassland and forest land was gradually increased due to the implementation of projects such as returning farmland to forests.Due to the Jiuzhaigou earthquake in 2017,the natural landscape of waters,grasslands and woodlands was significantly affected,and its area was reduced,and the area of unused land increased sharply.(2)During the study period,the area of plaque type and the area of plaque type in forest land landscape and the largest plaque index value were the highest,followed by grassland,but the number of grass plaques was more than other landscape types,indicating that forest land and grassland were the advantages of the study area and the grass is broken.From the level of landscape type scale,the degree of landscape fragmentation in the study area as a whole has increased.During 2012-2017,geological disasters caused by seismic activity were prominent,and the number of patches,plaque density and fragmentation index increased greatly,indicating that seismic activity has obvious control effects on landscape pattern changes in the study area.(3)This paper divides the 2.5km*2.5km evaluation unit to evaluate the vulnerability of the landscape pattern in the study area based on the landscape pattern vulnerability index model.The average vulnerability of the six types of landscapes is ranked from large to small: waters,woodlands,construction land,cultivated land,unused land and grassland.The vulnerability of the landscape pattern in the study area is mainly low vulnerability,and the area accounts for more than 60% of the entire study area.Secondly,it is a moderately vulnerable area,accounting for more than 25% of the entire study area;the potential vulnerable area accounts for about 7% of the entire study area;the highly vulnerable area only accounts for about 3% of the entire study area;the area of extremely high vulnerability area is less than 1.5%.In 2002-2007,the vulnerability of the landscape pattern in the study area was mainly growth.From 2007 to 2012,the vulnerability of the landscape pattern in the study area was mainly reduced.In 2012-2017,the vulnerability of the landscape pattern in the study area was mainly growth.Under earthquake induced,the area of moderate,high and extremely high fragile areas increased slightly,and the area of low fragile areas decreased slightly.(4)This paper establishes a GIS-Logistic coupling model to study the driving force of landscape pattern vulnerability.Potentially vulnerable areas are more likely to be soil types such as black felt soil,grass soil,etc.,moderate rainfall,high temperature and sunshine,the farther away from the ground disaster and the road,the closer the distance from the river.Low vulnerability areas are more likely to be leached to brown soil,dark brown soil,etc.,alpine soil such as black felt soil and grass felt soil,with less accumulated precipitation,close to the river,and high altitude areas.Moderately vulnerable areas are more likely to leaching into brown soil,dark brown soil,etc.,the slope is steep,the altitude is higher,the precipitation is more,and the areas with strong human disturbance gather.Highly vulnerable areas are more likely to gather closer to the road and where there is more precipitation.Highly vulnerable areas are more likely to gather closer to the road and where there is more precipitation.Very high-vulnerability areas are more likely to be closer to the road,people's quality of life is poor,agricultural development is slow,and areas with prominent geological disasters gather. |
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