Spatial-temporal Distribution Pattern And Influencing Factors Of Grassland Fires In Mongolia Plateau In Recent 20years

As a disturbing factor of grassland ecosystem,fire has an important influence on its ecological balance.Grassland is not only the main ecological barrier of land,but also the pasture and food source of livestock,which has important ecological,economic and social values.The Mongolian Plateau has vast grassland,and this area is also one of the areas where grassland fires are most serious.By studying the temporal and spatial distribution pattern and influence mechanism of grassland fire in Mongolia Plateau,it can provide data support for long-term prediction of grassland fire in the future,and also provide scientific basis for local fire prevention work and resource management.Based on MODIS remote sensing data,the information of burned areas in Mongolian Plateau from 2001 to 2020 was extracted.On this basis,the annual,seasonal and monthly changes of grassland fires in Mongolian Plateau in recent20 years were analyzed,and the spatial distribution characteristics of grassland fires were discussed.The spatio-temporal cube model is used to reveal the spatio-temporal evolution model of grassland fire-prone areas in Mongolian Plateau,which makes up for the deficiency of traditional spatial statistics in analyzing space,time or attribute separately,realizes the complete expression of space,time and attribute information,and effectively reveals the spatio-temporal characteristics and laws of grassland fire phenomenon.Then,according to the environmental factors related to grassland fire,the geographical detector method is used to detect the influence degree of single factor and the interaction between multiple factors,and the main influencing factors of natural and human activities on grassland fire in Mongolian Plateau are systematically revealed.The main conclusions of this paper are as follows:(1)During the period of 2001-2020,the number and area of grassland fires in Mongolian plateau showed a downward trend.From 2001 to 2020,there were 21,792 grassland fires in the Mongolian Plateau,with a cumulative area of211848.24 square kilometers and an average annual area of 10592.41 square kilometers.In the past 20 years,the accumulated fire area in Mongolia accounted for 88.37% of the total grassland fire area in Mongolia Plateau.The number of grassland fires in Inner Mongolia Autonomous Region in the past 20 years accounted for 64.50% of the total grassland fires in the Mongolian Plateau.On the perspective of seasonal scale,spring and autumn are the frequent periods of grassland fires in Mongolian Plateau.During the period of 2001-2020,the number of fires in spring and autumn accounted for 45.96% and 25.55% of the total number of fires in the whole year.On the monthly scale,the frequency and area of grassland fires in Mongolian Plateau show obvious bimodal distribution characteristics in March-May and September-October.(2)Generally speaking,the burned areas in Mongolian Plateau shows a decreasing trend from northeast to southwest.Administratively,it is mainly distributed in eastern Mongolia,Kent and Sukhbaatar provinces,Hulunbeier City,Inner Mongolia Autonomous Region,China and Xilin Gol League.On the scale of grassland type,the typical grassland has the largest burning area,followed by meadow grassland and desert grassland.By comparing the burned areas of different grassland types in Mongolia and China Inner Mongolia Autonomous Region,it is concluded that the burned areas of various grasslands in Mongolia are larger than those in China Inner Mongolia Autonomous Region.(3)Based on the spatio-temporal cube model,the spatio-temporal evolution pattern of grassland fire-prone areas in Mongolia Plateau is mined.It is concluded that the spatial and temporal autocorrelation of the largest area of grassland fire is complex and has poor regularity,and although the frequency of grassland fire is low on each grid,fires occur discontinuously and irregularly,with a wide spread.High-high clustering,high-low anomaly,low-low clustering and low-high anomaly have all appeared,which makes fire prevention and disaster reduction difficult.However,the individual points with significantly high or low frequency of grassland fires are mainly distributed in the towns where people gather,which indicates that the occurrence and prevention of grassland fires are related to population density and behavior.It is necessary to be alert to the recent high frequency of grassland fires and the frequent occurrence of grassland fires.(4)Geodetector can identify the nonlinear relationship between grassland fire area and its influencing factors,and quantitatively describe the contribution of each influencing factor to grassland fire.Natural factors are the factors that significantly promote the occurrence of grassland fires in Mongolian Plateau,and the factors that play a significant role in the interaction of multiple factors are the comprehensive effects of natural factors and human factors.However,human factors are the factors that significantly promote the occurrence of grassland fires in Inner Mongolia Autonomous Region,and the interaction between human factors plays an important role in the interaction of multiple factors.