Multi Scale Climate Driving Mechanism Of Forest Fire Risk In Changbai Mountain Area

Forest is the largest terrestrial ecosystem in the world and an important part of the global ecosystem.They play an important role in maintaining ecosystems and regulating climate.Forest fire is an important factor affecting forest ecosystem.According to statistics,200000 forest fires occur every year in the world.The area burned by forest fires accounts for more than 1% of the world’s total forest area every year.More than 10000 forest fires occur in China every year,accounting for more than 5% of China’s total forest area.These serious natural disasters cause serious economic losses every year.Changbai Mountain area is one of the areas with severe climate change in China.With the further warming of the climate,the amount and humidity of combustibles in Changbai Mountain forest area will further change.The NorthSouth span of Changbai Mountain area is large.Taking Changbai Mountain Area as the study area can well reveal the multi-scale relationship between climate and fire.Firstly,this paper analyzes the interaction between meteorological conditions,surface temperature and humidity,combustibles and fire occurrence in Changbai Mountain Area on daily and monthly scales,and then constructs climate fire relationship models on daily and monthly scales respectively,and analyzes the relative importance of driving factors in each climate area and the difference of partial dependence between driving factors and fire occurrence,The fire risk situation in Changbai Mountain Area from 2025 to 2050 in the future is predicted.The main results of the study are as follows:(1)On the one hand,the early climate conditions change the vegetation status by affecting the fuel accumulation,on the other hand,they also affect the fuel flammability in the short term through the lag effect.Different climatic factors have different effects on these two aspects of fire occurrence,that is,the specific effects of climatic factors on fire occurrence are different.The results show that in Changbai Mountain area,the impact of meteorological conditions in the first 1-2 months on the current fire is mainly controlled by the relationship between meteorological factors and surface temperature and humidity.For example,the sunshine time in the first month is positively correlated with the risk of fire,and the relative humidity in the previous month is negatively correlated with the risk of fire.The impact of earlier meteorological conditions on the current fire is mainly dominated by the relationship between meteorological conditions and vegetation growth.For example,the temperature in the first 2-5months is negatively correlated with fire,which is mainly caused by its positive correlation with vegetation growth.(2)In Changbai Mountain area,the humid climate conditions limit the occurrence of fire,so the dry and wet state is the leading factor affecting the occurrence of forest fire in Changbai Mountain area,and the importance of dry and wet state in the driving factors gradually increases from humid area to semi humid area.In the comparison of the three climate regions,it is found that the wetter the region,the less sensitive the fire risk is to the change of surface humidity.Due to the humid climate,the vegetation coverage in Changbai Mountain area is high and the combustibles are rich.The main factor limiting the fire is that the environment is relatively humid.Therefore,the impact of early climate conditions on the fire is smaller than that in the same period.In addition to meteorological conditions,the importance of human activity factors is not low,and the role of human factors in fire occurrence increases with the increase of altitude.In the daily scale model,the importance of altitude is the highest.Slope and other topographic factors account for a small proportion in the daily and monthly scale models.(3)Under the three "shared socio-economic paths" of miroc6 future climate model,the temperature and rainfall in Changbai Mountain area will increase from 2025 to 2050,and the risk of forest fire will also increase.In the socio-economic path where socio-economic activities will change the future climate more violently,the rising trend of temperature is more significant,and the rising speed of fire risk is faster.In terms of future fire risk distribution,high-risk areas are mainly distributed in low-altitude areas close to the scope of human activities.In the future,the fire risk in most areas will show an upward trend,especially in the low mountainous areas close to the human activity area.In a few areas,the fire risk will be reduced,and the places where the fire risk is reduced are mainly distributed in the central high mountain area.