| With the continuous development of human society,the construction of ecological civilization has become a global consensus.Ecological restoration of degraded land is an important part of ecological civilization construction and a key factor in achieving the goal of "double carbon",which has received widespread attention from the environmental community at home and abroad.Red soil area of Chinese southern is the second largest soil erosion area after the Loess Plateau,and Fujian Province is a typical red soil area of south China.Under the long-term high-intensity management,the soil erosion in the red soil area of Fujian has been effectively curbed.However,the spatial and temporal dynamics and development trend of ecological vulnerability in red soil area of Fujian are still unclear,and the formulation of ecological restoration measures and policies lacks scientific basis.How to accurately and continuously carry out ecological restoration work has become an urgent problem to be solved.Ecological vulnerability research can analyze the ecological vulnerability of the region,spatial and temporal change characteristics and the driving factors that cause the ecological vulnerability of the region,and provide scientific guidance for the direction of ecological restoration and management.In view of this,the red soil area in Fujian was taken as the research object,based on the "Ecological Sensitivity-Ecological Recovery-Ecological Pressure"(SRP)model,we used the Geospatial Data Cloud,USGS,Resource and Environmental Science and Data Center(REDC)and other platforms to obtain DEM,remote sensing image,meteorology,soil type,soil texture and socio-economic development data.We used Geospatial Data Cloud,USGS,Resource and Environmental Science and Data Center and other platforms to obtain data of DEM,remote sensing image,meteorology,geomorphology,soil type and socio-economic development,and used Arc GIS,ENVI and other software to extract 15 evaluation indexes such as elevation,land-use type and population density in red soil area of Fujian,and constructed the ecological vulnerability evaluation index system.Spatial principal component analysis,Global Moran’s I,LISA clustering map and CA-Markov model were used to evaluate the spatial and temporal dynamics of ecological vulnerability in red soil area of Fujian from2000 to 2020,and the base value was used to predict the ecological vulnerability in the next 10 years.The main results are as follows:(1)From 2000 to 2020,the overall ecological vulnerability of red soil area in Fujian decreased from moderate vulnerability to slight vulnerability,but locally in some years there were still ecological vulnerability increases.From the spatial change,the ecological vulnerability of red soil area in Fujian had significant spatial heterogeneity,and the ecological vulnerability of each prefecture-level city was ranked from high to low: Xiamen > Quanzhou > Fuzhou > Zhangzhou > Putian > Longyan > Nanping >Sanming > Ningde.Among them,severe and extremely vulnerable areas were mainly distributed in Fuzhou,Putian,Quanzhou,Xiamen,and Zhangzhou.The ecological vulnerability of mountainous and hilly areas such as the junction of Ningde and Nanping,the western part of Nanping,and the eastern part of Longyan was also strong.The prediction of the ecological vulnerability of red soil area in Fujian in the next 10 years finds that the ecological vulnerability in the next 10 years has improved compared with that in 2020,the area of slightly vulnerable areas increases 6.74%,and the area of mild,moderate,severe and extremely vulnerable areas decreased by 5.41%,0.41%,0.86% and 0.05% respectively.(2)There was a strong spatial positive autocorrelation in red soil area of Fujian,with global Moran’s I of 0.747,0.810,0.822,0.822 and 0.764 from 2000 to 2020,respectively.The number of scatter points in the first quadrant was significantly more than that in the third quadrant.It indicated that the ecological environment around the areas with higher ecological vulnerability was also more fragile,while the ecosystem around the areas with lower ecological vulnerability was also more stable,and there were more ecologically stable aggregation areas than ecologically fragile aggregation areas in red soil area of Fujian in the past 20 years.The "high high" aggregation areas in the red soil area of Fujian were concentrated in coastal areas with severe ecological fragility,while the "low" aggregation areas were mostly scattered in small areas.The "high-high" agglomerations were prone to the expansion of heavily and extremely fragile areas,the "low-low" agglomerations were ecologically stable and had a stronger ability to resist external disturbances.(3)Spatial principal component analysis was applied to analyze the drivers of ecological vulnerability in the red soil area of Fujian.It found that annual precipitation,NDVI and population density were the main influencing factors of ecological vulnerability in the red soil area of Fujian.In addition,the contribution of slope,topographic relief and GDP density to ecological vulnerability was also high.The ecologically severely and extremely vulnerable areas in the coastal localities of Fuzhou,Putian,Quanzhou,Xiamen and Zhangzhou overlapped highly with the concentrated areas of population and GDP density,and were mainly influenced by the common factors of annual precipitation,vegetation cover and human economic and social development.(4)Evaluation of ecological vulnerability in Changting County,a typical red soil area of Fujian,found that the ecosystem stability of red soil area in Changting was continuously improved from 2000 to 2020.From 2000 to 2005,the extent of the severely and extremely vulnerable areas in the urban area of Changting was increased.The spatial differences of ecological vulnerability in the red soil area of Changting were significant,and the ecological vulnerability was higher in the border mountain and hill areas and urban area,and the ecological environment in the central and southeastern areas was more resistant to disturbance.In the next 10 years,the comprehensive index of ecological vulnerability in Changting will decrease by 0.81 %,and the quality of ecological environment will be further improved.The spatial aggregation characteristics of ecological vulnerability in red soil area of Changting were significant.From 2000 to 2010,the number of ecological stability aggregation was more than that of ecological vulnerability aggregation,from 2015 to 2020,the number of ecological stability aggregation was similar to that of ecological vulnerability aggregation.In addition to topography,climate,human activities and economic development,the factors affecting the ecological stability of red soil area in Changting also included land use types,that was,the change of surface conditions in a small scale had an important impact on the change of ecological environment.(5)SRP model indexes are more comprehensive and easy to obtain,and the evaluation system focuses on socio-economic development factors,which is suitable for economic development-oriented areas with poor natural conditions.Using CAMarkov model to simulate the ecological vulnerability of study areas in 2020,it was found that the Kappa coefficient test values reach 0.768 and 0.884,and its accuracy meets the research needs.SRP and CA-Markov model are suitable for ecological vulnerability evaluation and short-term and medium-term prediction of red soil area.Markov models are suitable for ecological vulnerability evaluation and short-term and medium-term prediction in red soil areas.(6)In the future,the ecological environment restoration of red soil area in Fujian could mainly start from increasing effective vegetation coverage,driving the development of surrounding areas with high-density population and economic development areas,and alleviating the ecological pressure of core areas of population and economic development.At the same time,it takes into account the development of surface soil health,landscape type diversification and biodiversity in the red soil area of Fujian.The ecological environment restoration in red soil area of Changting should not only coordinate the ecological protection countermeasures in red soil area of Fujian,but also pay attention to the adjustment of land use structure. |
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