Assessing The Impact Of Climate Change On Forest Fire In Nepal Based On Time Series Remote Sensing Data

Climate change had a significant impact on forest fires.In the context of global warming,the number and size of forest fires were increasing,which had a adverse effect on global forestry production and economic development.Studying the spatial and temporal distribution of forest fires under climate change and clarifying the climate parameters of forest fires affecting the region were of great significance for regional forest fire management and forest fire prevention.Nepal had abundant forest resources and frequent fires.This paper took Nepal as a study area,extracted several forest fire-related climate parameters(precipitation,evapotranspiration,potential evapotranspiration)based on TRMM 3B43 and MOD16A2 climate datasets from 2001 to 2014,and calculated the second parameters(moisture balance,surface moisture balance,the ratio between evapotranspiration and potential evapotranspiration)related to forest fire,analyzed the spatial and temporal distribution characteristics of forest fire and climate parameters during 14 years,developed the grid based on correlation analysis between fire density and climate parameters both on interannual,seasonal scale.The purpose of this paper was to study the spatial and temporal distribution characteristics of forest fire and climate parameters and to clarify the main climate parameters affecting forest fires in Nepal and to identify the causes of variability in interannual fire seasons in Nepal.The main conclusions were as follows:(1)Temporal and spatial distribution characteristics of forest fires in Nepal from 2001 to 2014.In the period of 2001-2014,the forest fires in the Nepal area show an overall upward trend,and the areas affected by the fires also show an increasing trend.The fires fluctuate greatly throughout the year.In the 14 years of Nepal,the forest fires in the south are more than that in the north while the fires in the west are more than that in the east.Except for the plain area,the number of fire points decreases with increasing altitude.In spring,the fires are mainly located in the hilly area,where fires fluctuate greatly.Winter fires are mainly located in the high mountains,and the number of fires is small and stable.(2)Temporal and spatial distribution characteristics of climate parameters in Nepal from 2001 to 2014.The interannual evapotranspiration and potential evapotranspiration in Nepal have little fluctuation,the precipitation fluctuated greatly.The seasonal evapotranspiration and precipitation values show a cyclical pattern within one year,the potential evapotranspiration value decreases with the spring,summer,autumn and winter seasons.Evapotranspiration and potential evapotranspiration are not affected by changes in precipitation.The interannual and spring evapotranspiration and the potential evapotranspiration are distributed with the gradient of the topography.The evapotranspiration increases with the elevation,and the potential evapotranspiration decreases with the elevation.The precipitation is not significantly related to the topography,and the precipitation in the east is higher than that in the west.The distribution of evapotranspiration in winter is different from that in the interannual and spring periods.The evapotranspiration value in the high mountainous areas in winter is lower than that in the hilly area.Potential evapotranspiration is unaffected and also decreases with increasing altitude.The distribution of precipitation is different from that of interannual and spring.The precipitation in winter is slightly higher than that in the east,but the overall precipitation is very low.The interannual and interseasonal evapotranspiration has little fluctuation in space,and the potential evapotranspiration fluctuation is slightly larger than the evapotranspiration,and the spatial fluctuation of precipitation is more severe.(3)The main climatic parameters affecting forest fires in Nepal and the causes of seasonal variation of interannual forest fires in Nepal.Precipitation and evapotranspiration are negatively related to forest fire,and there are sporadic positive correlation regions.The potential evapotranspiration mainly shows positive correlation,while a small number of areas shows negative correlation.Moisture balance,surface moisture balance,the ratio between evapotranspiration and potential evapotranspiration are all negatively correlated with forest fire,and some regions are positively correlated.Interannual climate parameters variations are not the main factors affecting the interannual fire activities,which are affected by other natural factors or human activities.The correlations between potential evapotranspiration,the ratio between evapotranspiration and potential evapotranspiration and forest fires are higher on seasonal scale,which are the main climate parameter affecting winter and spring fire.The correlations between other climatic parameters and forest fire are closely related to spatial and temporal conditions.The low value of the ratio between evapotranspiration and potential evapotranspiration is the cause of fire-prone in Nepal,the relative variation between evapotranspiration and potential evapotranspiration has an important effect on the seasonal variation of interannual forest fires in Nepal.