Causes of post-fire runoff and erosion: water repellency, cover, or soil sealing?
Causes of post-fire runoff and erosion: water repellency, cover, or soil sealing?
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火灾后径流和侵蚀的原因：防水、覆盖或土壤密封？
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Mexico Keelin Schaffrath
中科院分区：
文献类型：
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作者：
I. Larsen;L. Macdonald;Ethan Brown;D. Rough;M. Welsh;J. H. Pietraszek;Z. Libohova;Juan De;Dios Benavides;Del Pacifi;Centro Parque;Los Colomos;Guadalajara Jalisco;Mexico Keelin Schaffrath
很少有研究试图找出可能导致高强度野火后峰值流量和侵蚀增加的各种因素。本研究通过以下方式评估了燃烧的影响：(i) 比较严重烧毁山坡、未烧毁山坡和通过耙地除去地表覆盖物的山坡的土壤防水性、地表覆盖和沉积物产量； (ii) 进行降雨模拟，以比较两种具有不同灰烬覆盖的土壤的径流、侵蚀和表面密封。仅在燃烧后第一个夏季，被火增强的土壤拒水性在被烧毁的山坡上比未被烧毁的山坡强。燃烧后的前 5 年，燃烧山坡的平均沉积物产量为 32 Mg ha ―1 ，而未燃烧山坡几乎不产生沉积物。当倾斜和烧毁的山坡具有可比的表面覆盖、降雨侵蚀力和土壤拒水性值时，它们产生的沉积物是无法区分的。与没有灰烬覆盖的地块相比，对被灰烬覆盖的地块进行的降雨模拟产生的径流仅为 21% 至 49%，沉积物为 42% 至 67%。土壤薄片显示，裸地迅速形成了结构性土封层。连续的模拟迅速侵蚀了灰烬覆盖层，并将径流和沉积物产量增加到从裸地观察到的水平。结果表明：（i）火灾后沉积物的产生主要是由于地表覆盖物的丧失，而不是火灾增强了土壤的防水性； (ii) 表面覆盖很重要，因为它会抑制土壤密封； (iii) 灰烬暂时阻止土壤密封并减少火后径流和沉积物产量。
Few studies have attempted to isolate the various factors that may cause the observed increases in peak flows and erosion after high-severity wildfires. This study evaluated the effects of burning by: (i) comparing soil water repellency, surface cover, and sediment yields from severely burned hillslopes, unburned hillslopes, and hillslopes where the surface cover was removed by raking; and (ii) conducting rainfall simulations to compare runoff, erosion, and surface sealing from two soils with varying ash cover. The fire-enhanced soil water repellency was only stronger on the burned hillslopes than the unburned hillslopes in the first summer after burning. For the first 5 yr after burning, the mean sediment yield from the burned hillslopes was 32 Mg ha ―1 , whereas the unburned hillslopes generated almost no sediment. Sediment yields from the raked and burned hillslopes were indistinguishable when they had comparable surface cover, rainfall erosivity, and soil water repellency values. The rainfall simulations on ash-covered plots generated only 21 to 49% as much runoffand 42 to 67% as much sediment as the plots with no ash cover. Soil thin sections showed that the bare plots rapidly developed a structural soil seal. Successive simulations quickly eroded the ash cover and increased runoff and sediment yields to the levels observed from the bare plots. The results indicate that: (i) post-fire sediment yields were primarily due to the loss of surface cover rather than fire-enhanced soil water repellency; (ii) surface cover is important because it inhibits soil sealing; and (iii) ash temporarily prevents soil sealing and reduces post-fire runoff and sediment yields.