Lethal soil temperatures during burning of masticated forest residues
Lethal soil temperatures during burning of masticated forest residues
复制标题
DOI：
10.1071/wf04062
复制
发表时间：
2005-01-01
影响因子：
3.1
通讯作者：
Powers, RF
中科院分区：
文献类型：
--
作者：
Busse, MD;Bussea, MD;Powers, RF
咀嚼木本灌木越来越多地被用作减少荒地-城市交界处火灾风险的管理选择。如果焚烧，产生的覆盖层是否会导致极端的土壤加热尚不清楚。我们测量了燃烧弧菌残留物过程中粘壤土中的温度分布。4个覆盖深度(0，2.5，7.5和12.5厘米)被烧毁，覆盖了加利福尼亚州北部有密集咀嚼前灌木覆盖的森林地点的典型条件。比较了每种燃料深度的两种土壤水分含量，以模拟春季规定的燃烧(潮湿土壤)和晚季野火(干燥土壤)。干燥土壤表面的最高温度达到600摄氏度，而潮湿土壤的最高温度要低100-200摄氏度。在干燥的土壤中，对于最深的两个覆盖深度，加热是广泛的，在整个10厘米的土壤剖面中，至少有7小时超过植物的致死阈值(60摄氏度)。在覆盖较少的情况下，发现最小的热脉冲。潮湿的土壤也抑制了热渗透；除了最深的覆盖层外，所有土壤剖面的最高温度都超过了60摄氏度到2.5厘米。在干燥或潮湿的土壤中，没有发现燃烧对拒水性的不利影响。在咀嚼后，尤其是在覆盖深度为7.5厘米或更深的干燥土壤中，存在火灾期间土壤加热造成生物损害的可能性。现场预测表明，在地表野火期间，多达四分之一的处理地区拥有茂密的咀嚼前植被，其土壤温度将超过致命的土壤温度。
Mastication of woody shrubs is used increasingly as a management option to reduce fire risk at the wildland - urban interface. Whether the resulting mulch layer leads to extreme soil heating, if burned, is unknown. We measured temperature profiles in a clay loam soil during burning of Arctostaphylos residues. Four mulch depths were burned ( 0, 2.5, 7.5 and 12.5 cm), spanning typical conditions at forested sites in northern California with dense pre- mastication shrub cover. Two soil moisture contents were compared at each fuel depth to simulate spring prescribed burning ( moist soil) and late- season wildfire ( dry soil). Maximum temperatures reached 600 degrees C on the surface of dry soils and were 100 - 200 degrees C lower for moist soil. Heating was extensive in dry soil for the two deepest mulch depths, exceeding the lethal threshold for plants ( 60 degrees C) for a minimum of 7 h throughout the 10- cm soil profile. Minimal heat pulse was found with less mulch. Moist soil also dampened heat penetration; peak temperatures exceeded 60 degrees C only to 2.5 cm in the soil profile for all but the deepest mulch layer. No adverse effects of burning on water repellency were found in dry or moist soil. The potential for biological damage from soil heating during fire exists following mastication, particularly in dry soil with a mulch depth of 7.5 cm or greater. Field projections indicate that up to one- fourth of treated areas with dense pre- mastication vegetation would surpass lethal soil temperatures during a surface wildfire.