Refining the cheatgrass-fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends.
Refining the cheatgrass-fire cycle in the Great Basin: Precipitation timing and fine fuel composition predict wildfire trends.
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DOI：
10.1002/ece3.3414
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发表时间：
2017-10
影响因子：
2.6
通讯作者：
Arkle RS
中科院分区：
文献类型：
--
作者：
Pilliod DS;Welty JL;Arkle RS
干旱和半干旱生态系统中更大、更频繁的野火与非本地一年生草的入侵有关，但人们对细燃料的发展和随后的野火趋势缺乏完整的了解。我们调查了美国大盆地的天气、精细燃料和火灾之间的复杂关系。我们首先模拟了北方大盆地26年来降水和温度对草本植被覆盖和凋落物积累的年度和时滞效应。然后，我们模拟了这些优良的燃料和天气模式如何影响随后的野火。我们发现，在降水量较高的年份，特别是在前3年中的一年也特别潮湿的时候，cheatgrass覆盖率会增加。非原生杂类草和原生草本植物的覆盖率在湿润年份也有所增加，但仅在几个干旱年份之后。在给定的一年中，野火烧毁的面积主要与原生草本植物和非原生杂类草覆盖有关，而cheatgrass主要影响以往年生长的凋落物形式烧毁的面积。因此，多年的天气模式，包括前1-3年的降水，是一个强有力的预测野火在给定的一年，因为需要时间来发展这些罚款燃料负荷。降水和野火之间的密切关系使我们能够将我们的推断扩展到1980年至2014年的35年间整个大盆地的10，162场野火。我们的研究结果表明，该地区的降水模式，连续多雨年，然后连续干旱年的结果在一个周期的燃料积累，其次是天气条件，增加野火事件的概率在一年中，当周期从湿到干的过渡。这些模式因地区而异，但足够强大，使我们能够仅根据降水量来模拟整个大盆地的年度野火风险。
Larger, more frequent wildfires in arid and semi‐arid ecosystems have been associated with invasion by non‐native annual grasses, yet a complete understanding of fine fuel development and subsequent wildfire trends is lacking. We investigated the complex relationships among weather, fine fuels, and fire in the Great Basin, USA. We first modeled the annual and time‐lagged effects of precipitation and temperature on herbaceous vegetation cover and litter accumulation over a 26‐year period in the northern Great Basin. We then modeled how these fine fuels and weather patterns influence subsequent wildfires. We found that cheatgrass cover increased in years with higher precipitation and especially when one of the previous 3 years also was particularly wet. Cover of non‐native forbs and native herbs also increased in wet years, but only after several dry years. The area burned by wildfire in a given year was mostly associated with native herb and non‐native forb cover, whereas cheatgrass mainly influenced area burned in the form of litter derived from previous years’ growth. Consequently, multiyear weather patterns, including precipitation in the previous 1–3 years, was a strong predictor of wildfire in a given year because of the time needed to develop these fine fuel loads. The strong relationship between precipitation and wildfire allowed us to expand our inference to 10,162 wildfires across the entire Great Basin over a 35‐year period from 1980 to 2014. Our results suggest that the region's precipitation pattern of consecutive wet years followed by consecutive dry years results in a cycle of fuel accumulation followed by weather conditions that increase the probability of wildfire events in the year when the cycle transitions from wet to dry. These patterns varied regionally but were strong enough to allow us to model annual wildfire risk across the Great Basin based on precipitation alone.
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