Vegetation Change And Its Response To Climate Change In The Mongolian Plateau From 2001 To 2018

The global climate change is a hot topic in current research.The Mongolian Plateau is an important part of the Eurasian continent.The climate change in this region is intense,which has obvious influence on vegetation.In this paper,the spatial and temporal distribution characteristics of gross primary production（GPP）and leaf area index（LAI）of the Mongolian Plateau were studied,and the variation trend was calculated by the trend analysis of unvariable linear regression to describe the change of vegetation.The temporal and spatial distribution pattern and variation trend of climate factors on the Mongolian Plateau were analyzed.The responses of vegetation to different climate factors were calculated through sensitivity analysis,contribution analysis and correlation analysis,and the responses of vegetation change on the Mongolian Plateau to climate change were analyzed.The main conclusions of this study are as follows:（1）The vegetation growth on the Mongolian Plateau has improved significantly from 2001 to 2018,and both GPP and LAI have shown an increasing trend,with growth rates of 3.89 g C m^-2 yr^-2 and 0.004 yr^-1,respectively.There are obvious differences in the change trend of vegetation in different spaces,showing an increasing trend in most areas and a decreasing trend in some areas.In the central part of Uvsu Province,northern Khuvsgul Province,southwestern Gobi Altai Province,northern and southern Khovd Province,southern Bayanhongor Province,southern South Gobi Province and northwest Alxa League in Inner Mongolia The northern part of the Xilin Gol League and the northern part of Chifeng City showed a downward trend.（2）The GPP and LAI values and changing trends are different under different vegetation types.From high to low,GPP values were as follows:broad-leaved forest,mixed forest,savanna,coniferous forest and farmland type.From high to low,LAI values were:mixed forest,coniferous forest,broadleaf forest,savanna,permanent wetland and farmland type.The growth rate of GPP was from high to low in different vegetation types:farmland,broadleaf forest,savanna,typical grassland,coniferous forest,mixed forest type;From high to low,LAI growth rates were:mixed forest,broadleaf forest,savanna,farmland and coniferous forest types.（3）There are also significant differences in the vegetation GPP and LAI values in different administrative regions,and the vegetation growth in the Inner Mongolia Autonomous Region of China is better than that of Mongolia.Among them,the multi-year average value of GPP in the Inner Mongolia Autonomous Region of China is391.13 g C m^-2 yr^-1,and the average annual growth rate is 5.05 g C m^-2 yr^-2;the multi-year average value in Mongolia is 213.84 g C m^-2 yr^-1,The velocity is 3.08 g C m^-2 yr^-2.The multi-year average of LAI in Inner Mongolia Autonomous Region is 0.42,and the annual average annual growth rate of LAI is 0.006 yr^-1;the multi-year average value of Mongolia is 0.20,and the annual average annual growth rate is 0.003 yr^-1.（4）The distribution patterns and trends of climate factors in the Mongolian Plateau from 2001 to 2018 have obvious spatial differences.The average annual growth rate of CO₂ was 1.91 mol mol^-1 yr^-1,and all regions of the plateau showed an increasing trend,especially from northwest to southeast.The average annual growth rate of solar radiation is-0.97 W m^-2 yr^-1,which generally shows a downward trend in the Mongolian Plateau and an upward trend in some parts of the central region.The average annual growth rate of precipitation was 2.51 mm yr^-1,showing an overall upward trend,and only a downward trend in some parts of the west and north.The average annual growth rate of soil moisture is 0.002 yr^-1,showing an overall upward trend.The average annual growth rate of soil temperature was-0.16℃yr^-1,showing a general downward trend,and an upward trend in the northern and northeast of the plateau.The average annual growth rate of temperature is 0.02℃yr^-1,showing an overall upward trend,and a downward trend in some areas such as the Greater Khingan Mountains in the northeast.（5）Climate factors in the Mongolian Plateau have a significant impact on vegetation GPP and LAI,and the main controlling factor is precipitation.An increase in precipitation to relieve drought stress is beneficial to vegetation growth,while an increase in temperature is not conducive to vegetation growth.There are regional differences in the influence of solar radiation on vegetation,but the overall effect is not significant.The growth of vegetation on the Mongolian Plateau is generally driven by climatic factors.Among them,53.27%of the area of GPP is driven by climatic factors,mainly driven by precipitation,accounting for 30.99%;55.72%of the area of LAI is driven by climatic factors,mainly driven by precipitation.,accounting for 32.66%of the area.Vegetation growth under different vegetation types is mainly driven by non-climatic factors,and the area driven by rainfall is the largest in shrubs,typical grasslands,farmland and other vegetation types.Under different administrative subjects,vegetation growth in the Inner Mongolia Autonomous Region is mainly driven by non-climatic factors,while in Mongolia it is mainly driven by climatic factors,among which precipitation is the main driving factor in the driving of climatic factors.