There is concern that forest management activities such as chemical thinning may increase hazardous fuel loading and therefore increase risk of stand-replacing wildfire. Chemical thinning, often accomplished by frill treatment of unwanted trees, leaves trees standing dead for a time before they fall and become surface fuels. In coastal northern California, frill treatment is used as a forest rehabilitation treatment that removes tanoak (Notholithocarpus densiflorus) to release merchantable conifers from excessive competition. We studied fuel bed depth and fuel loading after frill treatment of tanoak along a 16-year chronosequence that substituted space for time. The total depth of fuel bed was separated into woody fuels, litter, and duff. The height of each layer was variable and greatest on average in post-treatment year 5 after treated tanoak had begun to break apart and fall. Initially, the evergreen tanoak trees retained their foliage for at least a year after treatment. Five years after treatment, many tanoak had fallen and transitioned to become fine- and coarse woody debris. After 11 years, the larger pieces of down wood were mostly classified as rotten. After 16 years, the fuel loading appeared roughly equivalent to pre-treatment levels, however we did not explicitly test for differences due to potential confounding between time and multiple factors such as inter-annual climate variations and site attributes. Nevertheless, our data provide some insight into changes in surface fuel characteristics due to rehabilitation treatments. These data can be used as inputs for fire behavior modeling to generate indicative predictions of fire effects such as fire severity and how these change over time since treatment.

中文翻译：

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塔纳克森林恢复性装饰处理后释放燃料油和燃料深度的时间序列以释放道格拉斯冷杉：来自北加利福尼亚的案例研究

令人担忧的是，森林管理活动（例如化学间伐）可能会增加有害燃料的装载量，因此会增加代替林分野火的风险。化学稀疏通常通过对不需要的树木进行边缘处理来实现，使树木静置一段时间后才能掉落并成为表面燃料。在加利福尼亚州北部沿海地区，褶边处理被用作去除tanoak（Notholithocarpus densiflorus），以使适销性的针叶树摆脱过度竞争。我们研究了经过16年时间序列对tanoak进行褶皱处理后的燃料床深度和燃料负载，这些时间序列用空间代替了时间。油床的总深度分为木质燃料，垃圾和碎屑。每层的高度是可变的，并且在处理后的tanoak开始破裂并倒下后的第5年平均最大。最初，常绿的tanoak树在处理后至少一年保留其叶子。治疗五年后，许多tanoak坠落并转变为细木屑和粗木屑。11年后，大块的绒毛木材大部分被归类为烂。16年后，燃料装载量大致等于预处理水平，但是，由于时间和多种因素（例如年际气候变化和场所属性）之间可能的混淆，我们没有明确测试差异。然而，我们的数据提供了对由于康复治疗而引起的地表燃料特性变化的一些见解。这些数据可以用作火灾行为建模的输入，以生成火灾影响的指示性预测，例如火灾严重性以及自治疗以来随时间的变化。