Climate, Lightning, and Wildfire in the National Forests of the Southeastern United States: 1989-1998
Climate, Lightning, and Wildfire in the National Forests of the Southeastern United States: 1989-1998
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DOI：
10.2747/0272-3646.26.2.147
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发表时间：
2005-01
影响因子：
1.6
通讯作者：
Lori Jean Mitchener;A. J. Parker
中科院分区：
文献类型：
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作者：
Lori Jean Mitchener;A. J. Parker
我们编制了1989年至1998年期间美国东南部每个国家森林单位的野火记录，然后将年度火灾数量与闪电密度（由国家闪电探测网络记录）和气候干旱测量（季节性降水和帕尔默干旱严重指数[PDSI]值）进行回归。闪电引起的火灾在佛罗里达州最常见，那里的冬季季节性干燥，闪电密度高，增加了火灾的风险。总体回归模型一致认为，火灾季节PDSI是解释火灾时空格局最具影响力的解释变量，而闪电密度对野火区域格局的贡献不大。闪电密度只有在回归分析中包含佛罗里达州的一个离群森林单元时才会进入整体模型。对于地理上定义的区域回归模型，闪电密度仅在包括佛罗里达州在内的沿海平原东部地区有显著影响。除了研究区域中最干旱的部分奥扎克-瓦希托高地外，其他所有地区的气候干旱程度都是一致的。在其他地方，有效湿度的地理差异是突出的。在阿巴拉契亚高原潮湿的森林，长达12个月的干旱是促进燃烧的必要条件，但在温暖干燥的山前和沿海平原，引发大范围野火所需的前期干旱时间较短。
We compiled the record of wildfires from each national forest unit in the southeastern United States for the period 1989 to 1998, then regressed annual fire numbers against lightning flash densities (as recorded by the National Lightning Detection Network) and measures of climatic drought (seasonal precipitation and Palmer Drought Severity Index [PDSI] values). Lightning-caused fires were most common in Florida, where seasonally-dry winters and high lightning-flash density elevate fire risk. Overall regression models consistently identified fire-season PDSI as the most influential explanatory variable in accounting for the spatial and temporal pattern of fires, whereas the contribution of lightning-flash density to regional patterns of wildfires is muted. Lightning density only enters the overall model when a single outlier forest unit from Florida is included in the regression analysis. With respect to physiographically defined regional regression models, lightning density was only a significant influence in the Coastal Plain-East, which included Florida. Some measure of climatic drought was uniformly present in all other regions, except in the driest portion of the study region, the Ozark-Ouachita Uplands. Elsewhere, geographic variation in effective moisture is highlighted. Drought for periods of up to 12 months is necessary to promote burning in the wetter forests of the Appalachian Highlands, but periods of antecedent drought necessary to trigger widespread wildfires are shorter in the warmer and drier Piedmont and Coastal Plain.