3种针叶树地表凋落物燃烧蔓延速度比较

摘要

采用室内铁槽燃烧法,分别对油松 、樟子松和日本落叶松的地表凋落物进行了燃烧蔓延速度测定.结果显示:凋落物燃烧速度随着气温升高而逐渐加速,其中油松和樟子松凋落物的燃烧蔓延速度较快,日本落叶松凋落物燃烧蔓延速度较慢,在温度升至25℃ 时,3种针叶树凋落物燃烧速率分别比5℃时增长了39.32％、33.33％、33.33％;随着含水率的逐渐增大,3种针叶树凋落物燃烧蔓延速度均表现出逐渐减小的趋势,在含水率达到30％时,樟子松、油松凋落物燃烧蔓延速度分别比含水率5％时降低了339.3％、26.92％、53.33％;在上坡火中,坡度的增加对油松、樟子松和日本落叶松凋落物均表现燃烧蔓延速度加快的趋势,当坡度达到45°时,3种针叶树凋落物燃烧速率分别比无坡度时提高了100.0％、171.4％、12.50％.在下坡火燃烧当中,表现为坡度越大燃烧越慢的趋势.在坡度为45°时,油松、樟子松和日本落叶松凋落物的燃烧速率分别比无坡度时下降为59.32％、53.57％、68.75％.%We used the outdoor combustion method to measure the burning rate of surface litter of three kinds of coniferous trees including Pinus tabuliformis Carr., Pinus sylvestris var.mongolica Litv.and Larix kaempferi ( Lamb.) Carr..The burning rate of the litter increases with the increase of temperature.The burning of P.tabuliformis and P.sylvestris var.mongolica was faster followed by L.kaempferi.When the temperature rose to 25 ℃, the burn rates of litter were increased by 39.32％, 39.32％and 33.33％, respectively.With the gradual increase of water content, the spreading velocity of the three coniferous trees showed the decreasing trend.When the moisture content reached 30％, the rates of growth of P.tabulifor-mis, P.sylvestris var.mongolica.and L.kaempferiwere decreased by 33.93％, 26.92％and 53.33％, respectively.In the rising fire, the increase of slope was increased the tendency to accelerate the spread of P.atb uliformis, P. sylvestris var. mongolica and L.kaempferi.When the slope reached 45°, the combustion rate of litter increased by 100.0％, 171.4％and 12.50％, respectively. In the midst of a downward fire, the burn tendency turned more slowly, when the slope was higher. At a slope of 45°, the combustion rates of P.tabuliformis, P.sylvestris var.mongolica.and L.kaempferi were decreased to 59.32％, 53.57％and 68.75％, respectively.