Compaction and cover effects on runoff and erosion in post‐fire salvage logged areas in the Valley Fire, California
Compaction and cover effects on runoff and erosion in post‐fire salvage logged areas in the Valley Fire, California
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压实和覆盖对加利福尼亚州山谷大火火灾后抢救伐木区径流和侵蚀的影响
DOI：
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发表时间：
2020
影响因子：
3.2
通讯作者：
J. Wagenbrenner
中科院分区：
文献类型：
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作者：
S. Prats;M. Malvar;J. Wagenbrenner
野火和火后抢救伐木后径流和侵蚀过程可能会增加，但火后抢救伐木活动后土壤压实和地表覆盖对这些过程的具体影响知之甚少。我们在高强度野火和火后抢救伐木后进行了降雨模拟，以评估压实（火后抢救伐木期间未压实或被滑橇交通压实）和地表覆盖（裸露或被伐木斜线覆盖）的影响。无论压实状态如何，两次 30 分钟的模拟中，降雨量为 71 毫米后，裸地的径流相似（平均为 33 毫米）。相比之下，斜线覆盖地块的径流平均仅为 22 毫米。对于跨压实水平的裸地来说，下坡方向的雨溅平均为 30 g，而在斜线覆盖的地块上则显着减少了 70%。未压实和压实裸地的沉积物产量分别为 460 和 818gm−2，而砍伐显着减少了这些量，平均降幅为 71%。我们的结果表明，在高度严重的燃烧两年后，土壤侵蚀仍然很高，而土壤压实的影响却使径流和泥沙浓度的非显着增加使土壤侵蚀几乎增加了一倍。前期土壤湿度（干或湿）是控制径流的主导因素，而地表覆盖是降雨和产沙的主导因素。根据这些降雨模拟计算出的饱和导水率和细沟侵蚀性证实了之前的实验室研究，并将支持与野火和火后抢救记录相关的水文和侵蚀建模工作。用砍伐覆盖土壤可以减少径流并显着减少土壤侵蚀，这表明这种做法有可能减少烧毁和砍伐地区的沉积物产量和土壤退化。
Runoff and erosion processes can increase after wildfire and post‐fire salvage logging, but little is known about the specific effects of soil compaction and surface cover after post‐fire salvage logging activities on these processes. We carried out rainfall simulations after a high‐severity wildfire and post‐fire salvage logging to assess the effect of compaction (uncompacted or compacted by skid traffic during post‐fire salvage logging) and surface cover (bare or covered with logging slash). Runoff after 71 mm of rainfall across two 30‐min simulations was similar for the bare plots regardless of the compaction status (mean 33 mm). In comparison, runoff in the slash‐covered plots averaged only 22 mm. Rainsplash in the downslope direction averaged 30 g for the bare plots across compaction levels and decreased significantly by 70% on the slash‐covered plots. Sediment yield totalled 460 and 818 g m−2 for the uncompacted and compacted bare plots, respectively, and slash significantly reduced these amounts by an average rate of 71%. Our results showed that soil erosion was still high two years after the high severity burning and the effect of soil compaction nearly doubled soil erosion via nonsignificant increases in runoff and sediment concentration. Antecedent soil moisture (dry or wet) was the dominant factor controlling runoff, while surface cover was the dominant factor for rainsplash and sediment yield. Saturated hydraulic conductivity and interrill erodibility calculated from these rainfall simulations confirmed previous laboratory research and will support hydrologic and erosion modelling efforts related to wildfire and post‐fire salvage logging. Covering the soil with slash mitigated runoff and significantly reduced soil erosion, demonstrating the potential of this practise to reduce sediment yield and soil degradation from burned and logged areas.