Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after the 2007 Egley Fire Complex in Oregon, USA. We also assessed short- and long-term fuel treatment impacts on field-measured attributes one and nine years post fire. One-year post-fire burn severity (dNBR) was lower in treated than in untreated sites across the Egley Fire Complex. Annual NBR trends showed that treated sites nearly recovered to pre-fire values four years post fire, while untreated sites had a slower recovery rate. Time since treatment and dNBR significantly predicted tree canopy and understory green vegetation cover in 2008, suggesting that tree canopy and understory vegetation cover increased in areas that were treated recently pre fire. Live tree density was more affected by severity than by pre-fire treatment in either year, as was dead tree density one year post fire. In 2008, neither treatment nor severity affected percent cover of functional groups (shrub, graminoid, forb, invasive, and moss–lichen–fungi); however, by 2016, shrub, graminoid, forb, and invasive cover were higher in high-severity burn sites than in low-severity burn sites. Total fuel loads nine years post fire were higher in untreated, high-severity burn sites than any other sites. Tree canopy cover and density of trees, saplings, and seedlings were lower nine years post fire than one year post fire across treatments and severity, whereas live and dead tree basal area, understory surface cover, and fuel loads increased. Pre-fire fuel treatments effectively lowered the occurrence of high-severity wildfire, likely due to successful pre-fire tree and sapling density and surface fuels reduction. This study also quantified the changes in vegetation and fuels from one to nine years post fire. We suggest that low-severity wildfire can meet prescribed fire management objectives of lowering surface fuel accumulations while not increasing overstory tree mortality.

中文翻译：

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美国俄勒冈州埃格利火灾综合体相交的美国黄松燃料处理的短期和长期影响

燃料处理被广泛用于改变森林生态系统中的燃料，以减轻野火行为和影响。但是，很少有研究检查相互作用的燃料处理（商业收成，商业前的间伐，堆放和燃烧以及规定的火灾）和野火的长期生态影响。使用每年拟合的Landsat卫星衍生的归一化燃烧比（NBR）曲线以及成对的经过火处理和未经处理的现场，我们测试了差异NBR（dNBR）和自治疗以来数年的变化，以此作为生物物理属性的预测指标。 2007美国俄勒冈州埃格利消防中心。我们还评估了短期和长期燃料处理对火灾后1年和9年现场测量属性的影响。整个埃格利火灾综合体中，经过处理的一年火灾后烧伤严重程度（dNBR）低于未经处理的地点。NBR的年度趋势显示，火灾发生后四年，处理过的场地几乎恢复到火灾前的值，而未经处理的场地恢复速度较慢。自处理以来的时间和dNBR显着预测了2008年树冠和林下绿色植被的覆盖率，这表明在最近火灾前经过处理的地区树冠和林下植被的覆盖率有所增加。在任何一年中，活树密度受严重程度的影响比受火灾前处理的影响更大，火灾后一年死树的密度也受到火灾之前的影响。2008年，治疗和严重程度均未影响功能组的覆盖率（灌木，类动物，forb，侵入性和苔藓-地衣-真菌）；但是，到2016年，灌木，类葛粉，禁忌，高严重度烧伤部位的创面和侵袭覆盖率高于低严重度烧伤部位。火灾发生九年后，未经处理的高烈度燃烧场所的总燃料负载高于任何其他场所。在不同处理和严重程度下，树火后九年的树冠覆盖度和树木，树苗和幼苗的密度低于火后一年，而活树和死树的基础面积，林下表层覆盖和燃料负荷增加。预燃燃料处理有效地降低了高强度野火的发生，这可能是由于预燃树和树苗密度提高以及地表燃料减少所致。这项研究还量化了火灾后一到九年的植被和燃料变化。