Research On The Influence Of Climate Factors On NDVI Heterogeneity And Landscape Response Strategy In Shandong Province

Climate change has significantly altered regional and even global ecosystems,leading to distinct changes in vegetation growth scope,regularities of distribution and seasonality,which has an important impact on the quality of terrestrial habitats.In this paper,based on meteorological data from 20 meteorological stations and Normalized Difference Vegetation Index(NDVI)of 16 cities in Shandong Province from 1984 to 2019,the temporal variation characteristics of climatic factors and vegetation indices in different climatic regions in Shandong Province were analyzed through the Mann-Kendall method,linear regression method and sliding T-test method.By means of ensemble empirical mode decomposition(EEMD),the variation period of climate elements and vegetation indices was explored,and by means of empirical orthogonal function(EOF),the temporal and spatial change characteristics of climate elements and vegetation indices in different climatic regions were analyzed.The temporal and spatial change trends of climate elements and vegetation indices were predicted by R/S analysis.The Pearson Correlation Coefficient was used to analyze the effects of climate elements on the seasonal variation and spatial distribution of NDVI in different climatic regions as well as the lag effects of climate elements on vegetation.In addition,Geodetector was used to explore the differences of natural factors in different topographic regions on driving factors of vegetation indices.In the end,according to the research results,landscape ecological restoration strategies and planning and design schemes for regional vegetative landscape were proposed from macro,meso and micro levels to cope with climate change.The research results are as follows:(1)The climate factors in the five climatic regions of Shandong Province show significant differences in seasonal variation and spatial distribution.The mean seasonal temperature(Tmean),the mean seasonal maximum temperature(Tmax),the mean seasonal minimum temperature(Tmin)and the mean seasonal precipitation(Pmean)(except for autumn)all show an increasing trend(Z>0).Mean seasonal sunshine hours(S-Hmean),mean seasonal wind speed(W-Smean)and mean seasonal maximum wind speed(W-Smax)all show a decreasing trend(Z<0).With the exception of the spring S-Hmean mutation time in the 1980s,all other climate factors were mutated at the end of the 1990s and the beginning of the 21st century,respectively.EEMD analysis indicates that interannual oscillations combined with local interdecadal oscillations are the dominant periodic variation pattern.The EOF analysis shows that all climate factors in Shandong province are spatially dominated by the first mode,reflecting the overall consistency of climate change in Shandong province,but there are different regional variations in climate factors.The R/S analysis shows that the future trends of all climate factors in Shandong Province will remain consistent with the past,except for autumn Tmax,Pmean and winter Pmean,which are not consistent with the trends of the past 36 years,i.e.the trend is mainly warm and wet,with little wind and few days.(2)The NDVI in the five climatic regions of Shandong Province is characterized by significant seasonal differences and a variety of spatial distribution types.Overall,NDVI showed a significant increasing trend(Z>2.32),dominated by spring.Periodic variation is dominated by interannual oscillations but is locally influenced by interdecadal oscillations.EOF analysis shows that NDVI is all dominated by the first mode,but the time series trends are different,indicating regional differences.The R/S analysis shows that the future NDVI in Shandong Province is consistent with the trend of the last 36 years,i.e.it will continue to increase in the future,with spring being the main growth season,but with regional differences.(3)Among the climate factors in the five climate regions of Shandong Province,temperature and wind speed are the main influencing factors on the spatial and temporal variability and distribution of NDVI,with regional differences and time lags.Temperature has a significant effect(p<0.05)and a moderate positive correlation(except for the autumn mean seasonal maximum temperature),and wind speed has a highly significant effect(p<0.01)and a moderate negative correlation(p<0.01,r=-0.583)on the seasonal variation of NDVI in Shandong Province,and there are regional differences.The strongest lagged effect of summer climate factors on autumn NDVI in Shandong Province(r=0.465)and the weakest lagged effect of winter climate factors on spring NDVI in the previous year(r=0.402).The analysis of the influence of climate change on the spatial distribution of NDVI shows that only spring and winter climate factors have an inverse phase variation on the spatial distribution of NDVI.The geodetector analysis shows that the overall NDVI factor detection in Shandong Province is strongest in spring and weakest in summer,and there are seasonal differences among topographic regions.(4)Based on the results of the analysis of the spatial and temporal changes of climate factors and NDVI in Shandong Province and the mechanism of climate influence on NDVI,a landscape planning strategy to cope with climate change is proposed at three levels:macro,meso and micro,and based on the principles of climate orientation,ecological priority,biodiversity and local adaptation.Using triple protection measures for the front,middle and back dykes,we propose a land surface plant community configuration model that combines functionality and landscape,taking into account seasonal climate change and the needs of the seasonal phase of the vegetation landscape.Using a combination of "carbon-fixing,sink-boosting herbs+leafy,flowering shrubs+highly branched,large-canopy trees" to mitigate meteorological disasters such as high temperatures,droughts,floods and strong winds.The canopy line is enriched with sparse trees such as juniper(Cupressaceae Bartling)-ginkgo(Ginkgo biloba L.)-camphor(Cinnamomum bodinieri),dotted with pink hydrangea(Hydrangea suspensa(Thunb.)Ser.),Ma Tang(Digitaria sanguinalis(L.)Scop.),Forsythia(Forsythia suspensa(Thunb.)Vahl)and other native plants to increase the regional landscape diversity,forming a staggered belt of plant landscapes that respond to climate change.The dual effect of restoring and rebuilding plant ecosystems affected by meteorological disasters and improving the visual quality of the landscape is achieved.