Forest thinning practices play a fundamental role in natural resource management and are used to reduce forest density, particularly in the southwestern United States. Increased forest density can significantly influence fuel loads and subsequent fire severity. Moderate and high fire severity may increase surface runoff and sediment yield during postfire rainfall events. This study was conducted to evaluate the effects of thinning treatments on runoff and sediment yield in northern New Mexico forests. Four cover types were tested to evaluate how they influenced runoff and sedimentation. The four cover types included control (nonthinned), interspace (between slash piles), lop-scatter (slash was scattered and burned), and pile (slash was piled and burned). In addition, each cover type was tested on two categories of slopes: mild slopes (<5%) and moderate slopes (5% to 20%). Rainfall simulations (~16 cm h–1) for both dry and wet runs were used to measure runoff and sediment yield in 2015 and 2017. Results showed pile treatments had significantly higher time to runoff initiation than did control plots during dry runs. Time to peak runoff was significantly different in mild slope (38.1 min) than moderate slope (25.4 min) in the dry run. Wet run time to peak runoff was found to be greater under the pile treatment as compared to other treatments. Sediment yield was significantly greater on moderate slopes in pile and lop-scatter treatments as compared to control for dry runs. For wet runs, a significant effect was detected between slopes; moderate (greater) slopes produced greater sediment than mild (lesser) slopes. The pile treatments may provide beneficial impacts for watersheds despite the delayed peak runoff in response to rainfall on milder slopes. However, high sediment yield with runoff for pile thinning treatments in steeper slope locations will be important to include when evaluating management impacts on natural resources in the future. Overall, this case study shows that thinning activities in conifer forests of New Mexico have the potential to impact the hydrological function of the watershed and should be considered as part of an overall forest and watershed management strategy.

中文翻译：

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新墨西哥州北部森林中经过不同森林间伐作业的地区的径流和沉积物产量案例研究

森林间伐做法在自然资源管理中发挥着重要作用，用于降低森林密度，特别是在美国西南部。森林密度的增加会显着影响燃料负荷和随后的火灾严重程度。在火灾后降雨事件期间，中度和高度的火灾严重性可能会增加地表径流和沉积物产量。本研究旨在评估间伐处理对新墨西哥北部森林径流和沉积物产量的影响。测试了四种覆盖类型，以评估它们如何影响径流和沉积。四种覆盖类型包括控制（非稀释）、间隙（斜线堆之间）、垂散（斜线被分散和烧毁）和堆（斜线被堆积和烧毁）。此外，每种覆盖类型都在两类斜坡上进行了测试：轻度斜坡（< 5%）和中等坡度（5% 到 20%）。在 2015 年和 2017 年，干运行和湿运行的降雨模拟 (~16 cm h-1) 用于测量径流和沉积物产量。 结果显示，在干运行期间，桩处理的径流启动时间明显长于控制地块。在干运行中，温和坡度（38.1 分钟）与中等坡度（25.4 分钟）的达到峰值径流的时间显着不同。发现与其他处理相比，在桩处理下达到峰值径流的湿运行时间更长。与干运行的对照相比，在中度坡度上，在桩和坡度散射处理中的沉积物产量显着更高。对于湿滑，在斜坡之间检测到显着影响；中等（较大）斜坡比温和（较小）斜坡产生更多的沉积物。尽管由于缓坡上的降雨而延迟了高峰径流，但桩处理可能会对流域产生有益的影响。然而，在未来评估管理对自然资源的影响时，在较陡坡位置进行桩间疏处理的高产沙量和径流将是重要的。总体而言，本案例研究表明，新墨西哥州针叶林的间伐活动有可能影响流域的水文功能，应将其视为整体森林和流域管理战略的一部分。