Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA.
Litter Species Composition and Topographic Effects on Fuels and Modeled Fire Behavior in an Oak-Hickory Forest in the Eastern USA.
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DOI：
10.1371/journal.pone.0159997
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Peters MP
中科院分区：
文献类型：
--
作者：
Dickinson MB;Hutchinson TF;Dietenberger M;Matt F;Peters MP
中生树种（特别是红槭）正逐渐取代橡树（栎属）。在美国东部防火的落叶橡树山核桃林中。一个关键的假设是，来自中生植物凋落物的燃料床不太可能比来自橡树凋落物的床进行火灾，如果他们这样做，更有可能在较低的强度燃烧。物种的影响，但是，地形梯度，影响上层组成和燃料床分解混淆。为了研究凋落物种类组成和地形对地表可燃物床的单独和综合影响，我们在俄亥俄州丘陵的橡树山核桃林进行了一个普通的花园实验。每个公共花园包括主要由橡树和枫树凋落物组成的床，分别代表橡树和枫树为主的林分，以及两者的混合物。四年来，每年秋天都会补充床位。共同花园（N = 16）建立在四个地形位置（山脊，长椅上的南和东北面的斜坡，流梯田）在每个四个网站。凋落物源和地形位置有很大程度上独立的影响燃料床和模拟火动力学经过四年的发展。负载（公斤m-2）的上部凋落物层（L），层，主要支持火焰蔓延，是最少的mesic景观位置和枫树床，这意味着更大的分解率为这些情况。堆积密度在L层（kg m-3）是最少的橡木床，沿着与较高的负载，将促进火蔓延和火线强度。负荷和堆积密度的组合发酵和腐殖（FH）层是最少的流梯田的位置，但不相关的物种。枯落物和FH层的水分在5天的干燥期后的降雨事件的时间和地形效应的影响，而枯落物源的影响不明显。锥形量热仪测定的燃烧特性表明，橡木燃料床的火线强度更大，凋落物源和地形之间的相互作用也出乎意料。传播指数，它综合了一套燃料床，颗粒和燃烧特性，以表明传播（与灭绝）的潜力，主要是受凋落物来源，其次，由低传播潜力的梅西奇景观位置早在5天的干涸期。模拟火线强度得到了类似的结果。我们的研究结果表明，继续过渡，从橡树中生植物物种在俄亥俄州山将减少火灾蔓延的潜力和火灾强度。
Mesophytic species (esp. Acer rubrum) are increasingly replacing oaks (Quercus spp.) in fire-suppressed, deciduous oak-hickory forests of the eastern US. A pivotal hypothesis is that fuel beds derived from mesophytic litter are less likely than beds derived from oak litter to carry a fire and, if they do, are more likely to burn at lower intensities. Species effects, however, are confounded by topographic gradients that affect overstory composition and fuel bed decomposition. To examine the separate and combined effects of litter species composition and topography on surface fuel beds, we conducted a common garden experiment in oak-hickory forests of the Ohio Hills. Each common garden included beds composed of mostly oak and mostly maple litter, representative of oak- and maple-dominated stands, respectively, and a mixture of the two. Beds were replenished each fall for four years. Common gardens (N = 16) were established at four topographic positions (ridges, benches on south- and northeast-facing slopes, and stream terraces) at each of four sites. Litter source and topographic position had largely independent effects on fuel beds and modeled fire dynamics after four years of development. Loading (kg m-2) of the upper litter layer (L), the layer that primarily supports flaming spread, was least in more mesic landscape positions and for maple beds, implying greater decomposition rates for those situations. Bulk density in the L layer (kg m-3) was least for oak beds which, along with higher loading, would promote fire spread and fireline intensity. Loading and bulk density of the combined fermentation and humic (FH) layers were least on stream terrace positions but were not related to species. Litter- and FH-layer moistures during a 5-day dry-down period after a rain event were affected by time and topographic effects while litter source effects were not evident. Characteristics of flaming combustion determined with a cone calorimeter pointed to greater fireline intensity for oak fuel beds and unexpected interactions between litter source and topography. A spread index, which synthesizes a suite of fuel bed, particle, and combustion characteristics to indicate spread (vs extinction) potential, was primarily affected by litter source and, secondarily, by the low spread potentials on mesic landscape positions early in the 5-day dry-down period. A similar result was obtained for modeled fireline intensity. Our results suggest that the continuing transition from oaks to mesophytic species in the Ohio Hills will reduce fire spread potentials and fire intensities.