Fire as a driver of fungal diversity — A synthesis of current knowledge

Fires occur in most terrestrial ecosystems where they drive changes in the traits, composition, and diversity of fungal communities. Fires range from rare, stand-replacing wildfires to frequent, prescribed fires used to mimic natural fire regimes. Fire regime factors, including burn severity, fire intensity, and timing, vary widely and likely determine how fungi respond to fires. Despite the importance of fungi to post-fire plant communities and ecosystem functioning, attempts to identify common fungal responses and their major drivers are lacking. This synthesis addresses this knowledge gap and ranges from fire adaptations of specific fungi to succession and assembly fungal communities as they respond to spatially heterogenous burning within the landscape. Fires impact fungi directly and indirectly through their effects on fungal survival, substrate and habitat modifications, changes in environmental conditions, and/or physiological responses of the hosts with which fungi interact. Some specific pyrophilous, or “fire-loving,” fungi often appear after fire. Our synthesis explores whether such taxa can be considered cosmopolitan, and whether they are truly fire-adapted or simply opportunists adapted to rapidly occupy substrates and habitats made available by fires. We also discuss the possible inoculum sources of post-fire fungi and explore existing conceptual models and ecological frameworks that may be useful in generalizing fungal fire responses. We conclude with identifying research gaps and areas that may best transform the current knowledge and understanding of fungal responses to fire.

火在多数陆地生态系统中均有发生，其驱动真菌群落的性状、组成与多样性发生改变。野火类型跨度极大，从罕见的灭林型野火，到用于模拟自然火制度（fire regime）的高频控制性火烧。火制度相关因子，包括火烧烈度、火烧强度与火烧发生时序，均存在广泛变异，且大概率决定了真菌对火的响应模式。尽管真菌对于火后植物群落与生态系统功能至关重要，但目前学界仍缺乏对真菌共性响应及其主要驱动因子的系统性识别研究。本综合研究旨在填补这一认知空白，其研究范畴涵盖从特定真菌的火适应性，到响应景观内空间异质性火烧的真菌群落演替与组装过程。火可通过直接与间接途径对真菌产生影响，包括改变真菌存活条件、底物与生境特征、环境因子，以及真菌所共生宿主的生理响应。部分特定的嗜火真菌（pyrophilous fungi）往往会在火后大量出现。本综合研究将探讨这类类群是否具有广布性，以及它们究竟是真正适应火环境的类群，还是仅为快速占据火烧后裸露底物与生境的机会主义物种。我们还将讨论火后真菌的潜在接种源，并梳理现有可用于归纳真菌火响应模式的概念模型与生态学理论框架。本研究最后将总结当前的研究空白，并提出可推动我们对真菌火响应认知与理解实现革新的重点研究方向。