After the ‘Black Summer’ fires: faunal responses to megafire depend on fire severity, proportional area burnt, and vegetation type

Climate change and human activities have disrupted historical fire regimes, leading to complex and far-reaching impacts on global ecosystems. Despite extensive research in fire ecology, studies exploring vertebrate responses to megafires, and to nuanced fire characteristics, remain limited.
We collected camera trap data 3–27 months following Australia’s 2019–20 ‘Black Summer’ megafires from 30 burnt sites and 10 unburnt sites. Our data included 14 animal species/groups, encompassing mammalian predators, small and medium-sized mammals, large herbivores, and birds. We used generalised additive mixed models to assess the influence of time-since-the-fires, burn status, fire severity, proportional area burnt, and vegetation type on species' activity.
Models that included fire variables were well-supported for all species. The proportional cover of low-moderate or high-extreme severity fire had substantial support for five species, particularly herbivores, which generally showed a preference for burnt sites but at differing fire severities. The proportional area burnt, disregarding severity, was well supported for four species. At highly burned sites, fox activity peaked shortly after the fires, while small to medium-sized mammal activity increased more gradually. Vegetation type strongly influenced the response of four species to fire; in particular, wet forest birds preferred unburnt areas.

Policy implications. We document variable short- to medium-term responses of a range of species to fire which could help guide management interventions. We demonstrate that animal species’ responses to fire are diverse and better captured using broader landscape-scale fire variables. We found that species were strongly influenced by proportional area burnt, fire severity, and vegetation type. Introduced foxes were attracted to recently burnt areas, so timely predator control may benefit vulnerable prey species. Wet forest species were sensitive to fires and could benefit from preservation and restoration of these habitats. Some species exploited low-moderate severity burnt areas, while others preferred high-severity burns. This suggests that species will face diverse challenges and opportunities in future extreme fire events. We emphasise the importance of using multi-faceted approaches to account for the complex responses of co-occurring species to fire events.

气候变化与人类活动已打破了历史野火格局，对全球生态系统造成复杂且深远的影响。尽管野火生态学领域已有大量研究，但针对脊椎动物对大型野火（megafires）以及精细化野火特征的响应相关研究仍较为匮乏。

本研究于澳大利亚2019-2020年“黑色夏季”大型野火（megafires）发生后的3至27个月期间，在30个过火位点与10个未过火位点部署了相机陷阱（camera trap）并采集数据。本研究采集的数据涵盖14个动物类群/物种，包括哺乳类捕食者、中小型哺乳类、大型草食动物以及鸟类。本研究采用广义加性混合模型（generalised additive mixed models），评估了过火时长、过火状态、野火烈度、过火面积占比以及植被类型对物种活动的影响。

纳入野火变量的模型对所有物种均表现出良好的拟合支持效果。低-中度或高-极端烈度野火的覆盖占比对5个物种具有显著的模型支持度，其中草食动物普遍偏好过火区域，但对野火烈度存在差异化选择。仅考虑过火面积占比（不区分烈度）的模型对4个物种具有良好拟合支持效果。在高度过火的区域中，狐狸的活动在野火发生后短期内达到峰值，而中小型哺乳类的活动则呈现更为平缓的上升趋势。植被类型对4个物种的野火响应具有显著影响；其中，湿润林鸟类偏好未过火区域。

政策启示。本研究记录了多个物种种群对野火的差异化短期至中期响应，可为野火管理干预提供科学依据。研究表明，动物物种对野火的响应具有显著多样性，采用更大尺度的景观野火变量可更全面地刻画这类响应。本研究发现，物种的活动显著受过火面积占比、野火烈度以及植被类型的影响。外来引入的狐狸会被新近过火的区域吸引，因此及时开展捕食者防控或可惠及弱势猎物种群。湿润林物种对野火较为敏感，对其栖息地开展保护与修复将有助于这类物种的存续。部分物种会利用低-中度烈度的过火区域，而另一些物种则偏好高烈度过火区域。这意味着在未来的极端野火事件中，不同物种将面临差异化的挑战与发展机遇。本研究强调，需采用多维度研究方法，以解析同域共存物种对野火事件的复杂响应。