| With the gradual warming of the global climate and the continuous improvement of human living standards,the ecological environment on which humans depend has continued to be severely damaged as never before.This article comprehensively considers the severe challenges facing the terrestrial ecological environment in Taiwan Province.Based on the SPOT / VEGETATION NDVI satellite remote sensing image data from 1998 to 2018,it also combines data such as land use type data,DEM data,and administrative division data of Taiwan Province,Trend analysis method,stability analysis method,continuous analysis method and mathematical statistics and other related methods,studied the spatial and temporal pattern evolution characteristics and change trend of the normalized vegetation index(NDVI)in Taiwan Province of China from 1998 to 2018,and a scientific and systematic analysis of the stability and sustainability of the vegetation NDVI changes was made in order to provide some theoretical basis for regional sustainable development and ecological environmental protection.The main conclusions are:(1)From 1998 to 2018,the annual mean value of vegetation NDVI in Taiwan showed significant temporal and spatial differences in interannual changes.From the perspective of time change,the annual average value of vegetation NDVI over the past 21 years in Taiwan Province has shown a very significant overall growth trend(P <0.001),with an annual growth rate of 0.002.From the analysis of the quarterly scale,it can be seen that the vegetation in Taiwan Province has a certain degree of difference in the time variation of its NDVI in different seasons: the fastest growth rate of vegetation NDVI is winter,with a growth rate of0.0036 / year;the slowest growth rate is In autumn,the growth rate is 0.0020 / year;the growth rate of vegetation NDVI in spring and summer is the same,which is 0.0021 / year.However,the overall vegetation NDVI value in summer is significantly higher than that in spring.It can be found from the overall distribution of vegetation NDVI that summer is generally Taiwan Province.Vegetation growing season.From the perspective of spatial change,from 1998 to 2018,the spatial distribution of vegetation NDVI in Taiwan Province showed a trend of slowly improving year by year.With the passage of time,high-altitude regions such as the Central Mountain Range of Taiwan Province have formed a "green plant belt" that runs from north to south,and the " green plant belt " deepens year by year with thechange of the year.(2)The inter-annual change of vegetation NDVI in Taiwan Province from 1998 to 2018 mainly showed an improvement trend.From the perspective of different administrative divisions,the areas of severely degraded vegetation are mainly densely populated cities such as the western coast,and the areas of significant improvement are mainly the northern cities of Keelung and Taipei and the high-altitude areas of central Taiwan.From the perspective of different land use types,the vegetation NDVI of the five land use types of cultivated land,forest land,grassland,waters and unused land has shown a significant improvement trend,and the growth trend of vegetation NDVI in urban construction and residential land is degraded to the Lord.From the perspective of different elevation gradients,the overall NDVI of the vegetation showed different degrees of improvement.With the increase of the elevation gradient,the vegetation NDVI in Taiwan Province has been seriously degraded,slightly degraded,and the proportion of the area that is basically unchanged has gradually increased.The area ratio of the area with slight improvement gradually increased,and the area ratio of the area with obvious improvement showed a trend of decreasing first and then increasing.(3)The standard deviation of NDVI of vegetation in Taiwan Province from 1998 to2018 is between 0.009 and 0.211.The overall NDVI of vegetation presents a trend of "high in the west and low in the north,high in the north and low in the south,high and low fluctuations,coexistence of high and low fluctuations,and mostly low fluctuations".From the perspective of different administrative divisions,high fluctuation areas are mainly concentrated in major coastal cities such as the municipalities of Taiwan Province;moderate fluctuation areas are mainly concentrated in county-level cities along the western coast of Taiwan Province;low fluctuation areas are mainly distributed in the central mountains of Taiwan Province and it is obviously banded.From the perspective of different land use types,the inter-annual changes of the three types of land use vegetation,residential land,unused land,and water area,have a high wave dynamic trend;the inter-annual changes of cultivated land vegetation NDVI show a medium wave dynamic trend;forest land,grassland two types of land The interannual variation of the use type vegetation NDVI showed a low-wave dynamic trend.From the perspective of different altitude gradients,the vegetation NDVI fluctuations are most obvious in the range of <500m altitude.In the range of 500-1500 m,1500-2000 m,2000-2500 m,2500-3100 m,the degree of vegetation NDVI fluctuations is relatively small.In the range of >3100m,the vegetation is significantly restricted by hydrothermal conditions,and the degree of fluctuation of NDVI is relatively high.(4)The Hurst index of vegetation in Taiwan is between 0.136 and 0.866,with an average value of 0.48,The regional vegetation NDVI of up to 61.45% is anti-persistent,and28.55% of the vegetation NDVI is persistent.In the future,the regional vegetation NDVI change in Taiwan Province will show an improvement trend(70.59%),the regional vegetation will show an anti-continuous change,that is,most of the vegetation NDVI in this area may show a degradation trend,but this degradation trend is relatively weak.Most of the areas where vegetation NDVI showed positive continuity were concentrated in Kaohsiung County in the south of Taiwan Province,most areas in the north of Pingtung County,and most areas in central Nantou County,the interannual changes in vegetation NDVI in this area showed an improvement trend,vegetation in some areas will show continuous improvement in the future. |
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