Decadal impacts of wildfire fuel reduction treatments on ecosystem characteristics and fire behavior in alaskan boreal forests
Decadal impacts of wildfire fuel reduction treatments on ecosystem characteristics and fire behavior in alaskan boreal forests
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DOI：
10.1016/j.foreco.2023.121347
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发表时间：
2023-10
影响因子：
3.7
通讯作者：
M. A. Boyd;X. Walker;Jennifer Barnes;G. Celis;S. Goetz;J. Johnstone;Nicholas T. Link;A. Melvin;Lisa Saperstein;E. Schuur;M. Mack
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文献类型：
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作者：
M. A. Boyd;X. Walker;Jennifer Barnes;G. Celis;S. Goetz;J. Johnstone;Nicholas T. Link;A. Melvin;Lisa Saperstein;E. Schuur;M. Mack
随着气候变暖和干燥，北方森林的野火活动正在增加，增加了农村和城市社区的风险。在阿拉斯加内陆的黑云杉森林中，减少燃料的处理方法被用来创造一个可防御的空间，用于灭火和减缓火势蔓延。这些治疗方法引入了新的干扰特征，使生态系统结构和野火风险降低的长期结果不确定。我们重新测量了一个网络的网站，燃料减少，通过手工间伐或机械剪刃在阿拉斯加内陆，以评估如何演替轨迹的树的优势，林下成分，和永久冻土的变化超过20年后治疗。我们还评估了相对于未经处理的黑云杉林，这些减少燃料的处理是否会降低模拟的表面火灾蔓延率（ROS）、火焰长度和火线强度，以及表面火灾行为是否会随着时间的推移而变化。在间伐区，土壤有机层（SOL）的干扰促进树苗招聘，但并没有随着时间的推移而改变。在剪刃网站，相比之下，针叶树和阔叶落叶苗密度随着时间的推移而增加，落叶苗比云杉丰富20倍。解冻深度增加，随着时间的推移，在这两个治疗，是最大的剪刃的网站与薄SOL。林下植物组成没有改变变薄，但在剪刃处理转移到高落叶灌木和草随着时间的推移，从杂类草和马尾草。模拟的表面火灾行为是恒定的剪切刀片网站。这一发现与专家意见不一致，突出表明需要更多的燃料具体数据，以捕捉不断变化的植被结构。治疗效果在减少模拟表面活性氧，火焰长度，火线强度依赖于燃料模型用于未经处理的黑云杉立场，指出这些治疗的疗效在减轻表面火灾行为的不确定性。总的来说，我们表明，燃料减少治疗可以促进低可燃性，落叶树为主的演替轨迹，剪刃有很强的影响林下组成和永久冻土退化，持续近二十年后的干扰。这些因素需要考虑，以提高设计，管理和预测的火灾行为在这些治疗。
Wildfire activity is increasing in boreal forests as climate warms and dries, increasing risks to rural and urban communities. In black spruce forests of Interior Alaska, fuel reduction treatments are used to create a defensible space for fire suppression and slow fire spread. These treatments introduce novel disturbance characteristics, making longer-term outcomes on ecosystem structure and wildfire risk reduction uncertain. We remeasured a network of sites where fuels were reduced through hand thinning or mechanical shearblading in Interior Alaska to assess how successional trajectories of tree dominance, understory composition, and permafrost change over ∼ 20 years after treatment. We also assessed if these fuel reduction treatments reduce modeled surface rate of fire spread (ROS), flame length, and fireline intensity relative to an untreated black spruce stand, and if surface fire behavior changes over time. In thinned areas, soil organic layer (SOL) disturbance promoted tree seedling recruitment but did not change over time. In shearbladed sites, by contrast, both conifer and broad-leaved deciduous seedling density increased over time and deciduous seedlings were 20 times more abundant than spruce. Thaw depth increased over time in both treatments and was greatest in shearbladed sites with a thin SOL. Understory composition was not altered by thinning but in shearbladed treatments shifted from forbs and horsetail to tall deciduous shrubs and grasses over time. Modeled surface fire behavior was constant in shearbladed sites. This finding is inconsistent with expert opinion, highlighting the need for additional fuels-specific data to capture the changing vegetation structure. Treatment effectiveness at reducing modeled surface ROS, flame length, and fireline intensity depended on the fuel model used for an untreated black spruce stand, pointing to uncertainties about the efficacy of these treatments at mitigating surface fire behavior. Overall, we show that fuel reduction treatments can promote low flammability, deciduous tree dominated successional trajectories, and that shearblading has strong effects on understory composition and permafrost degradation that persist for nearly two decades after disturbance. Such factors need to be considered to enhance the design, management, and predictions of fire behavior in these treatments.