| Coastal cities are rich in natural resources and geographical advantages.The ecological quality of coastal areas is one of the important factors affecting the sustainable development of coastal cities.Qingdao city has frequent sea and land economic activities.It is an area with dense population and strong economic and social activities.It is a typical coastal city in China.Studying the temporal and spatial change pattern and distribution law of its ecological environment quality has important guiding significance for promoting the ecological environment protection and restoration of coastal cities.This paper took Qingdao city as the research object,based on four issues of remote sensing image data in 2005,2009,2014 and 2019 and constructed the remote sensing based ecological index（RSEI）model of Qingdao city by extracting index information such as greenness（NDVI）,humidity（WET）,dryness（NDBSI）and heat（LST）.The temporal and spatial variation and distribution characteristics of ecological environment quality in Qingdao city were studied.Through human-computer interaction interpretation,this paper revealed the temporal and spatial changes of vegetation cover types in Qingdao city,and studied the impact of vegetation cover on the quality of ecological environment,in order to provide theoretical basis and guidance for the ecological restoration and governance development of Qingdao city coastal zone.The results of this research were as follows:（1）The remote sensing ecological index model of Qingdao city can better reflect the information of each component index and accurately characterize the change of ecological environment quality in Qingdao city.In the RSEI model,the average correlation coefficients of the four component indexes of greenness,humidity,dryness and heat are 0.707,0.621,0.587 and 0.751 respectively.The average correlation coefficient between the RSEI value and the four component indexes is 0.803,which is higher than the average correlation coefficient among the component indexes.Therefore,the correlation between the RSEI value and each index is the highest,Using remote sensing ecological index model to comprehensively reflect the changes of ecological environment quality in Qingdao city is more reasonable and accurate.（2）The eco-environmental quality of Qingdao city has a great relationship with the greenness and humidity in the component indicators.The greenness and humidity are positively correlated with the eco-environmental quality,and the dryness and heat are negatively correlated with the eco-environmental quality.From 2005 to 2019,the average values of NDVI and WET showed an upward trend year by year,and the average values of NDBSI and LST first increased and then decreased,but also showed an upward trend on the whole.The contribution rate of NDVI and wet to the remote sensing ecological index model is positive,and the contribution rate of NDBSI and LST to the remote sensing ecological index model is negative,which indicates that the greenness and humidity promote the ecological environment,and the dryness and heat weaken the ecological environment.At the same time,among the four component indicators,humidity and greenness contribute the most to the remote sensing ecological index model,indicating that humidity and greenness have a great impact on the ecological environment quality of Qingdao city.（3）The eco-environmental quality of Qingdao city was on the rise,and the spatial distribution was generally better in the central urban area than in the suburbs.The average RSEI in 2005,2009,2014 and 2019 were 0.433,0.468,0.470 and 0.578respectively.From 2005 to 2019,the areas with good and excellent eco-environmental quality in Qingdao city continued to rise,while the areas with poor and poor eco-environmental quality in Qingdao city continued to decline.The eco-environmental quality level has changed from medium and poor to good and medium.Except in 2005,the eco-environmental quality of other years is medium or above,which exceeds 75%of the total area.From 2005 to 2019,the areas with improved eco-environmental quality and areas without obvious changed in Qingdao city accounted for more than 90%of the total area,far higher than those with decreased eco-environmental quality.The areas with improved eco-environmental quality were mainly distributed in Laoshan district,the north of Laixi district,the northeast of Pingdu district and other forest parks and forest farms.The areas with deteriorated eco-environmental quality were concentrated in Shibei district,Shinan district,Licang district,Chengyang district and other central urban areas,as well as the coastal areas of Jiaozhou bay and the western coast.（4）Over the past 15 years from 2005 to 2019,the change of vegetation coverage in Qingdao city has shown obvious characteristics of"five increases and two decreases",that is,the increase of forest land,shrub land,sparse forest land,other forest land and grassland,and the decrease of farmland and non-vegetation areas.The change of vegetation coverage has an important impact on the improvement of ecological environment quality in Qingdao city.Compared with 2005,the area of forest land,shrub land,open forest land,other forest land and grassland increased by 101.35km~2,82.51km~2,25.08km~2,8.51km~2 and 119.46km~2,respectively.And the area of farmland and non-vegetation area decreased by 252.67 km~2 and 84.24 km~2 respectively.From the perspective of structural transformation,the main type of vegetation coverage was farmland,accounting for more than 50%of the total land area,followed by sparse forest land,forest land and grassland.The sum of the three land types accounts for 20%-30%of the total land types,while the sum of shrub forest land and other forest land accounts for relatively small proportion of the total area.From the perspective of the transfer direction of various types,the study area was mainly transferred out from farmland and vegetation free area,and the transfer in was mainly woodland,shrub woodland and grassland.The areas with improved ecological quality were mostly forest parks,wetland parks and areas with abundant forest land and grassland.The areas with poor ecological quality were mostly non vegetated areas and new artificial construction land. |
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