Wildfires typically transform vegetation and litter into a heterogeneous layer of ash and charred material covering the soil surface that can substantially modify the postfire hydrological and erosive response. To further elucidate the influence of postfire covering layers on sheet and concentrated flow erosion, we carried out laboratory rainfall and inflow simulations on 5 distinct soil surface conditions: bare soil, with a protective cover of char, ash, stones, and a combination thereof simulating field conditions. Each of 3 replicate simulations per treatment involved 4 runs, the first 2 simulating just rain (at 56 mm hr⁻¹) under dry and wet soil conditions and the next 2 simulating rain together with inflow at high and extreme rates (0.76 and 1.4 L min⁻¹). Overall runoff over the 4 runs together was lower for all 4 types of protective cover than for bare soil, but ash and char were clearly less effective than stones and, in particular, field conditions with runoff reductions of 25%, 23%, 40%, and 70%, respectively. Stones and field conditions were similarly effective in reducing overall erosion rates (with 47% and 77%, respectively), whereas ash and char even slightly increased overall erosion rates compared to bare soil. Ash and char were effective in reduction erosion but only during the first 2 runs under simulated rainfall. The greater effectiveness of the field conditions suggested synergistic effects between its 3 components, probably due to the stones enhancing infiltration and increasing flow resistance, thereby hampering detachment of ash and char and/or enhancing their deposition.

中文翻译：

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在实验室条件下比较表土木炭，灰分和石材覆盖对火灾后水文和侵蚀反应的影响

野火通常会将植被和凋落物转化为覆盖土壤表面的异质灰烬和烧焦的物质，这可以大大改变火灾后的水文和侵蚀反应。为了进一步阐明火灾后覆盖层对薄板和集中流动侵蚀的影响，我们在5种不同的土壤表面条件下进行了实验室降雨和入流模拟：裸露的土壤，用炭，灰，石头保护覆盖物，以及它们的组合模拟现场条件。每个处理的3个重复模拟中的每一个都涉及4个运行，前2个模拟在干燥和潮湿的土壤条件下仅降雨（56 mm hr ^-1），接下来的2个模拟降雨以及高和极高流量（0.76和1.4 L最小^-1）。这4种防护覆盖层的全部4个径流的总径流都比裸土低，但灰分和木炭显然不如石头，特别是在田间条件下，径流减少了25％，23％，40％ ，和70％。石头和田间条件同样有效地降低了总侵蚀率（分别为47％和77％），而与裸土相比，灰分和木炭甚至略微提高了总侵蚀率。灰分和木炭对减少侵蚀有效，但仅在模拟降雨下的前两个运行中有效。田间条件的更大有效性表明了其3种成分之间的协同作用，这可能是由于石头增强了渗透作用并增加了流动阻力，从而阻碍了灰分和木炭的分离和/或增强了它们的沉积。