Study On The Dead Surface Fuel Loading And Combustibility Of Different Forest Types In The Southeastern Foothills Of The Greater Xing’an Mountains,Inner Mongolia

The purpose of this study was to explore the potential combustibility of surface dead fuel and its response mechanism to forest fire in different forest types.In this thesis,five forest types including larch forest-white birch mixed forest,white birch forest,larch forest,white birch-aspen mixed forest,and Mongolian oak forest are the main research objects,Set up 50 sample plots to investigate the forest stand,site factors and dead combustibles in the sample plot,Determine the physical and chemical properties of dead combustibles such as moisture content,ignition point,calorific value,ash content,etc,Establish a multiple linear regression model between the total load of dead combustibles on the surface and the influence factors;Using principal component analysis method to evaluate the combustibility of dead combustibles on the surface of different forest types;Using the Coats-Redfern integral method to describe the pyrolysis behavior of the dead combustibles on the surface in the air atmosphere.The main results are as follows:The surface dead fuel load of Larix olgensis-Birch mixed forest,Silver birch forest,Larix sylvestris forest,Birch-Aspen mixed forest,and Quercus mongolica forest respectively are:48.635 kg·m^-2,49.399 kg·m^-2,55.626 kg·m^-2,54.281 kg·m^-2,39.155kg·m^-2.Among them,the total load of dead combustibles on the surface of the mixed forest of Larix olgensis and white birch is relatively high,Mainly manifested as a significant positive correlation with tree height and canopy closure（P<0.05）,In Larix gmelinii surface dead fuel loading estimation model:P<0.05,R²=0.825,R²=0.775after adjustment,F=16.458,statistically Regression relatively good results,the accuracy is relatively high.Five forest types of surface dead fuel moisture content between about 6.0%to20.0%,The ash content is between 1.0%and 5.0%,the calorific value is between 16.0kj·g^-1 and 20.0kj·g^-1,and the ignition point is between 270.0°C and 290.0°C.The moisture content of dead combustibles in the five forest types is significantly negatively correlated with calorific value,ash content is significantly negatively correlated with calorific value and ignition point,and calorific value is significantly positively correlated with ignition point.4 of 5 kinds of physical and chemical properties of forest types were principal component analysis showed that the five forest types of surface dead fuel integrated combustion from strong to weak:white birch-aspen forest>birch>Mongolian oak forest>Xing’an Larch-white birch mixed forest>Xing’an larch forest.Studies have shown that five forest types pyrolysis basically divided into dehydration,fast pyrolysis,charring three stages.By calculating the pyrolysis characteristic evaluation index P pyrolysis behavior,wherein the pyrolysis behavior 1h Delay combustibles from hard to easy follows:larch Larix-Birch forest>birch>Mongolian oak forests>Larix gmelinii>birch-Aspen mixed forest.The pyrolysis behaviors of combustibles with 10h time lag are as follows:Larix olgensis-Birch mixed forest>Birch forest>Birch-Populus alba mixed forest>Larix olgensis forest>Quercus mongolica forest.The pyrolysis behavior of combustibles with a time lag of 100h is as follows:Mongolian oak forest>Xing’an larch-white birch mixed forest>Xing’an larch forest>white birch forest>white birch-poplar mixed forest.By calculating the activation energy E to evaluate its thermal stability,which 1h Delay combustible thermal stability in order were:Larix larch forests>birch-aspen forest>birch>Mongolian oak forest>larch Larix-Birch Mixed forest.The thermal stability of combustibles with a 10-hour time lag is as follows:Mongolian oak forest>Xing’an larch-white birch mixed forest>white birch forest>white birch-aspen mixed forest>Xing’an larch forest.The thermal stability of combustibles with a time lag of 100h is as follows:Larix gmelini forest>Larix gmelini-Birch mixed forest>Quercus mongolica forest>Birch forest>Birch-Populus alba mixed forest.