Research On The Difference Of Wildfire Risk Drivers In Different Climate Regions Of Inner Mongolia Based On Bayesian Network

Wildfires play an essential ecological role in flammable ecosystems,affecting the vegetation distribution and structure,the carbon cycle and climate.Wildfires have double effects in fire-prone ecosystems around the world.On the one hand,wildfires bring benefits to people,which are regarded as a management tool to maintain forest health,promote biodiversity and reduce fuel accumulation.On the other hand,serious economic and ecological losses and even casualties may be caused by them.The Inner Mongolia Plateau(IMP)is located in the typical land transect of IGBP,which is the most sensitive area of global change,wildfires are extremely active and have had a significant impact on the ecological environment of the area.Therefore,understanding the drivers of contemporary wildfires in IMP is especially important for the proper management of wildfires to promote local ecosystem health and reduce the damage caused by fires.This paper established a Bayesian network model that can take into account the dependencies and interactions between drivers,analyzed the differences and changes in the importance of wildfire drivers in different climatic regions of IMP from 2001 to2015,and revealed the spatiotemporal dynamic characteristics,which made up for the shortcomings of previous studies.The main conclusions are as follows:(1)In humid region,the humid climate limits the dryness of vegetation,so temperature was the dominant factor affecting wildfires.Important factors included distance from the railway,elevation and fractional vegetation cover(FVC);In the sub-humid region,due to the relatively few combinations of climatic factors within the region(mainly moderate temperature and rain or low temperature and rain),and the influence of these climatic conditions on wildfires is similar,the difference of fire regimes caused by climate characteristics is relatively small compared with the other two regions.The railway construction status not only reflects the intensity of human activities,but also affects the land use and the connectivity of vegetation,so it becomes the dominant factor to determine the difference of regional fire regimes,and the important factors included FVC,temperature and precipitation;In arid region,due to the limitation of fire regimes by fuel,FVC is the dominant factor controlling the occurrence of wildfires.Important factors are composed of precipitation,temperature,distance from the settlements,and humidity.(2)During the period of 2001-2015,the trends in the importance of wildfire drivers in different regions varied significantly.The importance of wildfire driving factors in humid region was relatively stable,showing only volatility and no obvious trend of change;In the semi-humid region,the importance of the driving factors of wildfire was obviously changed,among which the distance from the railway and GDP were significantly increased,and the effects of temperature,humidity and elevation were significantly reduced;In the arid region,the importance of precipitation was significantly increased,and the importance of settlements was significantly reduced.(3)Under the control of temperature and altitude,the distribution pattern of fire risk in the humid area was high in the east and low in the middle and west.The middle and high fire risk areas are concentrated in the east,and the middle area also has scattered medium risk,while the west risk is relatively low.As a whole,the fire risk spatial distribution of all levels is relatively clustered;Under the control of railway and FVC,the spatial pattern of fire risk in the semi humid area was characterized by high risk areas in the east and northwest,and low risk areas in other areas.The central and southern areas are mainly low-risk areas,and the medium risk is scattered in the area.Compared with the other two areas,the fire risk distribution in the three states is relatively discrete;Under the control of FVC,precipitation and humidity in arid region,the fire risk gradually decreased from the east to the southwest.The high-risk areas are concentrated in the northeast,most of the eastern and central areas are medium-risk,while the risk in the west is relatively low.The spatial distribution of fire risk in the three states is relatively clustered.(4)During the period of 2001-2015,the changes in fire risk in all three regions were mainly caused by the increase in precipitation.The degree of wildfire risk change in each region was determined by the change rate of important drivers.The risk of wildfires in the humid area decreased as a whole,and increased in the east,but decreased from the middle to the west;The proportion of decreasing area and increasing area was approximately the same.Most of the western area,the eastern edge and the southern edge showed an increasing trend,while the eastern and western edge showed a decreasing trend;The fire risk in arid areas had increased overall,with an increasing trend in the east and central areas,and a decreasing trend in the northeast and western areas.