Evaluating post‐wildfire logging‐slash cover treatment to reduce hillslope erosion after salvage logging using ground measurements and remote sensing
Evaluating post‐wildfire logging‐slash cover treatment to reduce hillslope erosion after salvage logging using ground measurements and remote sensing
复制标题
使用地面测量和遥感评估野火后伐木斜面覆盖处理，以减少抢救性伐木后的山坡侵蚀
作者：
P. Robichaud;S. A. Lewis;Robert E. Brown;E. D. Bone;E. Brooks
美国西部持续的漫长而广泛的野火季节强调了更好地了解野火影响的必要性，包括火灾后的管理方案。我们对火后山坡侵蚀和流域响应（如洪水、产沙和泥石流）的理解的进步最近受到了相当大的关注。清除枯树的潜在影响，称为抢救性伐木，已被研究，但使用遥感图像抢救性伐木后，以评估空间格局和恢复是新颖的。2015年北星星火提供了一个机会，评估减少山坡侵蚀使用两个现场实验和巧合的遥感图像超过3年。采用四种流速的模拟细沟实验，与仅燃烧的对照相比，在有和没有添加采伐迹地的情况下，对集材机小径上的山坡侵蚀进行量化。七个复制的山坡淤泥围栏地块与相同的治疗方法也进行了评价自然降雨事件。使用WorldView-2卫星图像，使用多时相归一化差异植被指数（NDVI）值，将两个实验之间的地面覆盖和可侵蚀裸露土壤联系起来。结果表明，与模拟细沟实验中的斜线处理的滑道（0.34 g s-1）或对照（0.04 g s-1）相比，滑道产生了更多的沉积物（0.70 g s-1）。同样，在自然降雨条件下，坡面淤泥围栏地块的产沙量（3.42 Mg ha−1）显著高于经采伐迹地处理的坡面淤泥围栏地块（0.18 Mg ha−1）或对照地块（0 Mg ha−1）。0.32的归一化植被指数值对所有地块在所有年份对应的地面覆盖约60%，这是一个既定的阈值减少侵蚀。植被指数，地面覆盖，沉积物值之间的显着关系表明，植被指数可以帮助管理人员评估地面覆盖和侵蚀潜力远程干扰后，如野火或打捞伐木。
Continuing long and extensive wildfire seasons in the Western US emphasize the need for better understanding of wildfire impacts including post‐fire management scenarios. Advancements in our understanding of post‐fire hillslope erosion and watershed response such as flooding, sediment yield, and debris flows have recently received considerable attention. The potential impacts of removing dead trees, called salvage logging, has been studied, however the use of remotely sensed imagery after salvage logging to evaluate spatial patterns and recovery is novel. The 2015 North Star Fire provided an opportunity to evaluate hillslope erosion reduction using two field experiments and coincidental remotely sensed imagery over 3 years. Simulated rill experiments with four flow rates were used to quantify hillslope erosion on skidder trails with and without added logging slash compared with a burned‐only control. Seven replicated hillslope silt fence plots with the same treatments were also evaluated for natural rainfall events. WorldView‐2 satellite imagery was used to relate ground cover and erodible bare soil between the two experiments using multi‐temporal Normalized Differenced Vegetation Index (NDVI) values. Results indicate that the skid trails produced significantly more sediment (0.70 g s−1) than either the slash treated skid trail (0.34 g s−1) or controls (0.04 g s−1) with the simulated rill experiment. Similarly, under natural rainfall conditions sediment yield from hillslope silt fence plots was significantly greater for the skid trail (3.42 Mg ha−1) than either the slash treated skid trail (0.18 Mg ha−1) or controls (0 Mg ha−1). An NDVI value of 0.32 on all plots over all years corresponded to a ground cover of about 60% which is an established threshold for erosion reduction. Significant relationships between NDVI, ground cover, and sediment values suggest that NDVI may help managers evaluate ground cover and erosion potential remotely after disturbances such as a wildfire or salvage logging.