| The main forest types in LiaoHe source National Forest Reserve are studied in this paper.Through the field surveys,field experiments and statistical these methods.The fuel load of different forest types and levels was studied.A model for estimating the load of combustibles in the canopy is established.and the physical and chemical characteristics and spatial distribution characteristics of the main types of combustibles,potential fire lines and different types of combustibles in Liaohe source nature reserve are analyzed.And Be based on the Rothermel forest fire model,the potential forest fire behavior of main fuel types in Liaohe source National Forest Reserve was analyzed.The research results provide theoretical and technical basis for forest fire prevention and fighting in the protected area.The main conclusions are as follows:(1)There is a significant difference in surface fuel load between different forest types in Liaohe source National Nature Reserve.The load of surface combustibles on the surface is high,the load of surface combustible in the almond forest is 5.99kg/m2,the flammable material load of the pine woodland is 4.40kg/m2,the combustible load of the Robinia woodland surface is 3.69kg/m2,and the surface load of the surface of the tussah forest is 2.03kg/m2,the surface combustible load of the white birch forest is 2.04kg/m2,the burden of ground flammable material in cultivated Yang Lin was 2.69 kg/m2,and the flammable load on the surface of larch forest was 3.72 kg/m2,and the combustible load on the surface of poplar forest was 3.59kg/m2.The highest loadability of surface herbaceous combustible materials was 5.576 kg/m2,the lowest being 2.347 kg/m2 locust forest.The highest load of birch forest was 0.39 kg/m2,followed by Robinia pseudoacacia forest was 0.27 kg/m2,and the lowest was Yang Lin 0.13 kg/m2.(2)The load of canopy fuel in coniferous forest is relatively large,which is the main material basis for the occurrence of crown fire.The fuel load of Pinus tabulaeformis crown showed a trend of small ends and large middle areas.The fuel load was relatively concentrated in the height range of 5?7 meters.In the composition of fuel load per layer,the percentage of dry 100 is the largest in all layers.The highest proportion of fuel load in larch tree is the living branch.In the most concentrated load of 5 meters,the load of Larch crown is mainly composed of live branches.The load of Larch fuel is relatively concentrated in the height range of 5?8 meters.When the crown load of the coniferous forest is lower,the distribution of the crown is more uniform in the lower and higher levels,while the distribution of the crown is relatively concentrated at the middle and high levels when the load is high.(3)The physical and chemical properties of different tree species are quite different,affecting the flammability of tree species.The weighted calorific values of Betula platyphylla,poplar and cultivated poplar were 19.138J/g,18.641J/g and 18.569J/g,followed by coniferous tree species.The heat values of Pinus tabulaeformis and Larix were not different,17.698J/g and 17.252J/g respectively.The weighted calorific values of apricot and Robinia pseucloucacia were the lowest,only 15.644J/g and 15.718J/g,respectively.And 15.666J/g.In the weighted ash content of combustibles,the apricot is the highest,which is 1.93%closer to 2%.The ash content of poplar,cultivated poplar,oak tree and Robinia pseudoacacia is higher,1.84%,1.84%,1.79%and 1.72%,followed by Pinus tabulaeformis and larch,and the ash is about 1%.The ash content of Betula platyphylla is the lowest,which is 0.84%.The highest weighted surface area volume ratio is 2184.97 and 2072.45 for poplar and cultivated poplar,followed by Robinia pseudoacacia,1733.87,and then Pinus tabulaeformis and larch,1702.51 and 1710.15 respectively,and the lower one is oak and birch,and the surface area volume ratio is only 1470.74 and 1540.65,respectively.(4)The wind speed is the main factor affecting forest fire behavior.Under the condition of no wind and mean wind speed,the flame spread rate,flame height and flame intensity of the eight forest types will increase with the increase of the slope three.The change of the three fire behavior indexes is not obvious or even not obvious under the two different wind forces.However,when the wind speed is high,the main factors affecting fire behavior will be affected.(5)The influence of slope on forest fire behavior is obviously different in different forest types.When the slope reached a maximum of 20 degrees,the spread rate of Populus poplar was the fastest under the condition of no wind,which was 6m/min,and the cultivated Yang Cizhi was about 3m/min of 4.3m/min conifers.Robinia pseudoacacia,oak and Betula platyphylla forest had the lowest and minimum spread rate and flame height.They are 1.7m/min,1.23m/min and 0.83m/min,respectively.When the slope reached a maximum of 20 degrees,the flame intensity of the apricot forest was the largest under no wind condition,and the flame intensity was I532KW/m,while coniferous forest and poplar forest were 902KW/m,664KW/m and 737KW/m respectively,and the lowest in Robinia pseudoacacia forest,cultivated Yang Lin and tussah forest.Under the monthly mean maximum wind speed,the flame height and flame intensity will decrease significantly with the slope change trend.The fire intensity of mountain apricot forest is mainly due to the wood factor and the load of the surface fuel in the forest.The thickness of the litter layer will greatly reduce the rate of forest fire spread.The litter layer on the surface is thin and the speed is fast.(6)The surface fuel load of major forest types is the key factor affecting the intensity of surface fire.In terms of coniferous forests,the surface fire intensity of Pinus tabulaeformis was higher than that of Larix gmelinii.In broad-leaved forest,the canopy density of the whole stand is higher,less affected by human life,high fuel load on the surface,deep flammable bed layer and low load richness. |
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