Analysis Of Dynamic Changes And Driving Forces Of Vegetation Fractional Coverage In Shenzhen

Since the global ecological environmental change becomes more and more serious,the surface vegetation coverage becomes the indicator of regional ecological health more and more obviously.It is of great significance for the improvement of the ecological environment in the future to grasp the dynamic change law and driving factors through long-term Vegetation Fractional Coverage monitoring.In this paper,Landsat series of multi-temporal remote sensing images during the growing season?May to November?are used to explore the spatial and temporal variation characteristics of VFC in Shenzhen,the response to climate factors,and the driving and prediction of VFC dynamic changes.In the study of spatial and temporal variation characteristics of VFC,the center of gravity spatial migration model is used spatially,partial correlation analysis and T test,multiple correlation analysis and F test as well as dynamic stability model are used temporally.In the analysis of the driving and prediction of the dynamic change of vegetation,principal component analysis?PCA?is used to conduct the driving analysis based on the regional yearbook data,and the CA-Markov model is used to predict the land surface vegetation coverage in 2024.Here are the main conclusions as follow:?1?Long-term sequence image dynamic analysis shows,the average Fveg of Shenzhen from 2000 to 2018 is 0.50,mainly distributed in the southeast,west and several northern areas,accounting for 78.47%of the total study area.Combining with the terrai n change,it is mainly suitable for H=300?800m,slope=0?20°,aspect=southwest?SW?,northeast?NE?and southeast slope?SE?.Its migration characteristics are from northwest to southeast to northwest,and the migration rate is 551.21m·a^-1.On the timeline,over the past 19 years,the VFC mean value of annual growth season in Shenzhen has shown an overall upward trend(2.8×10^-3yr^-1,P<0.1),which is related to the quality of regional attention in green development.After observing it has stability,which is characterized by overall stability and weak in high volatility,accounting for only 0.73%of the total area.?2?Response analysis of Fveg and climatic factors in Shenzhen shows that the effect of temperature on the Fveg dynamic is higher than that of precipitation.For many years,the average annual temperature and cumulative precipitation in Shenzhen wer e 23.34?and 2234.05mm respectively,due to the expansion of urbanization,the temperature in the VFC distribution area is lower than that in the densely populated area,and the precipitation is vice versa.we take 2011 as the time node,both temperature and precipitation show a trend of"decreasing first and increasing later",but not as fast as the former in speed,so the overall performance is"dry cooling",and the relevant reduction rates are 0.083?··a^-1and 66.01mm·a^-1.By analyzing the influence of meteorological factors alone,the mean partial correlation coefficient of temperature and VFC is-0.081,reaching a significant level?P<0.05?,the positive and negative correlation area ratios are 2.81%and 4.97%,respectively showing a weak negative correlation effect.The mean partial correlation coefficient of precipitation and VFC is-0.042,the same level?P<0.05?,the ratio of positive and negative correlation area is 1.10%and 2.16%,respectively showing a slight negative correlation effect.After analyzing the effect and VFC composite average,air temperature,precipitation,and the partial correlation coefficient of VFC is 0.302,the area proportion s only related to the temperature significantly is 6.61%,only associated with a significant precipitation is 2.09%,both related to air temperature and precipitation is 1.35%,so the temperature of the main factors that affects the VFC changes in the study area.?3?With the increase of population over the years,the change of vegetation coverage in Shenzhen is mainly driven by the number of enterprises,government financial revenue and expenditure as well as the development of the third industry.Secondly,in the context of a large population base,the education level of the whole population?the number of employees and students at schools?is a secondary driver.Follow by that,the scientific innovation is the"booster"of social and economic development.Finally,the development of regional transportation?highway,railway,water transportation,aviation,etc.?and the government's macro-control are important factors for the change of vegetation coverage.?4?The CA-Markov model is used to model the land cover classification in two scenarios?theoretical scenario and natural scenario?in Shenzhen in 2024:The proportion of vegetation types is not significantly different,and the threshold of difference is0%?1.22%.Although the theoretical scenario can describe the detailed information of land cover,it is not strong enough to explain the simulated geographical expression.In the natural scenario,the area changed from 2014 to 2024 is 6967.68hm².Among them,arbor forest,cultivated land,grassland and water have a decreasing trend,while shrub,bare land and building land appearing an increasing trend.88.94%of the arbors mainly evolved into building land,shrub land and bare land,905.83 hm² cultivated land mainly evolved into building land and arbor forest,and 53.51%of the grassland changed into building land.