Ecological Vulnerability Characteristics Of Qingdao Coastal Zone Based On Landscape And Soil Erosion Pattern

The coastal zone of Qingdao has frequent economic activities on land and sea.It is the region with dense population and strong economic and social activities.It is also a typical ecological vulnerability zone in China.In recent years,under the influence of tourism,aquaculture development and urbanization,ecological environment problems have become increasingly prominent.The vulnerability assessment of coastal ecological environment based on the analysis of landscape and soil erosion patterns has attracted much attention.In order to explore the spatial distribution and influence of ecological environment vulnerability in Qingdao coastal zone,this paper takes Qingdao as the secondary coastal zone according to the“Trisection method”.Eight coastal districts of the city(namely,Huangdao District,Jiaozhou City,Jimo District,Chengyang District,Laoshan District,Licang District,northern District and southern District)were selected as the study areas.Based on the three periods of remote sensing image data in 1999,2009 and 2018,landscape ecology and GIS spatial analysis technology are applied to study the temporal and spatial variation characteristics of landscape pattern and ecological vulnerability in Qingdao coastal zone with the help of RUSLE soil loss equation evaluation method.The impact of soil erosion pattern changes on ecological vulnerability and the evolutionary relationship between soil erosion intensity and ecological vulnerability were discussed.In order to provide theoretical basis and scientific support for ecological vulnerability assessment,ecological restoration and sustainable development and utilization of urban coastal zones.(1)The landscape pattern showed dynamic change characteristics,and the area of each landscape type changed greatly.In the past 20 years,the area of forest land,water area and residential and industrial land has always been increasing,while the area of cultivated land and unused land tend to decrease.As the main landscape type,cultivated land was transferred to residential and industrial land and forest land in a large area.The transfer of various land use types to residential and industrial land has led to an obvious expansion trend.The overall performance was from the southern coastal Jiaozhou Bay area to the surrounding area.At the same time,due to the occupation of cultivated land and unused land by urban expansion,its area decreased,and the increase of forest land and water area mainly depended on the transfer of cultivated land.(2)From 1999 to 2018,the overall landscape type vulnerability of the study area was shown as unused land,grassland,forest land,cultivated land,residential and industrial land and water area.The patch density of six landscape types showed an upward trend,and the overall ecological suitability changed little.While the aggregation degree and reciprocal dimension of water area were the highest,and the vegetation cover index of forest land was always at a high level.Unused land,grassland and forest land were the landscape types with high vulnerability in Qingdao coastal zone.Their system stability was weak,they were easily degraded due to the disturbance of human factors and external environment,and their self-recovery ability was weak.(3)The ecological vulnerability of Qingdao coastal zone was dominated by mild vulnerable areas,and the structure of each vulnerability level changed significantly.On the whole,it was high in the east and southwest and low in the middle.The ecological vulnerability of the study area was mainly manifested in three changing trends: first decrease and then increase,first increase and then decrease,and continuous decrease.Qingdao was in a high vulnerability area,and the proportion of severely vulnerable areas in the entire study area was decreased from 22.86% to 1.06%.The ecological environment has been improved,and at the same time,the land in the severely vulnerable area has changed to a good ecological situation,resulting in the expansion of the vulnerable areas and the general vulnerable areas.(4)There was a significant negative correlation between ecological vulnerability and the degree of land use(P<0.01),that is,the higher the degree of land use,the lower the ecological vulnerability.The correlation coefficients between the ecological vulnerability index and the comprehensive index of land use degree at the three study time points were-0.866,-0.791 and-0.790 respectively.Meanwhile,the dynamic degree of land use in the two time periods of1999-2009 and 2009-2018 was 2.36 and 2.13.This showed that the degree of dynamic between different species decreased and the frequency of mutual transformation decreased.The ecological vulnerability was affected by the degree of development and utilization of land use.When the degree of landscape fragmentation was improved and the landscape tended to be stable,ecological vulnerability would decline.(5)The change of soil erosion intensity and ecological vulnerability in Qingdao coastal zone were synergistic.There were adjacent grade transformation and cross grade transformation between them,and their changes were basically the same as the change trend of ecological vulnerability.From 1999 to 2018,the degree of soil erosion generally increased first and then decreased,which is basically consistent with the change of ecological vulnerability situation.The change range of soil erosion intensity index during cross grade transformation in ecological vulnerable areas was significantly greater than that during transformation in adjacent ecological vulnerable areas.(6)The development and utilization of Qingdao coastal zone should be based on the characteristics of vulnerability change,and pay attention to the impact of landscape change and soil erosion change on the ecological environment.We should strengthen the control of activities such as sea reclamation and land reclamation.We will continue to promote the construction of Qingdao as a "National Forest City" and the construction of ecological protection forests in coastal areas,and improve the forest coverage rate in various regions.At the same time,we will continue to improve the stability of Qingdao's coastal ecosystem and the ecological environment quality of offshore areas.