Analysis On The Delay Law Of Vegetation Growth Response To Climate And Time Multi-scale Characteristics In The Loess Plateau

With the global warming,the study of the relationship between vegetation growth and climate change becomes crucial,especially for those ecosystems that are vulnerable to climate change,such as those in arid and semiarid regions.The ecological environment of the Loess Plateau is fragile,located in the transition zone of semi-humid,semiarid and arid regions,and provides ecosystem services for approximately 100 million Chinese people.Therefore,understanding the relationship between the vegetation and climate in the area is very important for decision-makers to make appropriate plans to better manage this densely populated but ecologically fragile area.This article is based on the third generation of Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index(GIMMS NDVI 3g)dataset from 1982 to 2015,the dataset of precipitation and temperature of 52 meteorological stations on the Loess Plateau,and MODIS land cover change data from 2001 to 2012.Using a new weighted time-lag method,linear regression analysis,and Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(Improved CEEMDAN)and Support Vector Machine(SVM),the influence of different vegetation coverage on the Loess Plateau on climate factors is discussed the delay effect and the degree of influence of climate factors on vegetation at different time scales.The main findings of this article are as follows:(1)Under the assumption of three months delay,different vegetation in the Loess Plateau has different degrees of response to temperature and precipitation in different months from 1982 to 2015.The study shows that precipitation is the main driving factor affecting vegetation growth.(2)The response of three natural vegetation to the same climate factor in different months in the Loess Plateau accounted for a certain proportion,among which the cumulative impact of climate in the first three months accounted for the largest proportion,and the same vegetation type also had different responses to different climatic factors.(3)The end effect of EMD method can be reduced to some extent by using SVM,and the mode aliasing phenomenon of EMD method can be separated by adding different noises in Improved CEEMDAN method to obtain more accurate time scale components.(4)At different scales,the response of different vegetation types to climate factors showed obvious differences.In general,the relationship between vegetation and climate factors can be analyzed by using multi-scale decomposition,and it can be concluded that temperature has a greater impact on different vegetation types.The relationship between vegetation cover change and climate change is a complex interaction process.Considering the delay effect of vegetation index on climate change in the Loess Plateau can largely explain the changes in the process of vegetation growth,which is very important for the prediction and evaluation of vegetation dynamics and climate change in the Loess Plateau.Moreover,using multi-scale method to study the relationship between vegetation growth and climate factors can more accurately reveal the new relationship between vegetation and climate under different scales,which provides new ideas for exploring the relationship between vegetation and climate and other factors,and provides scientific decision support for the governance of global ecological environment.Figure[26]Table[7]reference[187]...