Fungal community structure and seasonal trajectories respond similarly to fire across pyrophilic ecosystems

Abstract

Fire alters microbial community composition, and is expected to increase in frequency due to climate change. Testing whether microbes in different ecosystems will respond similarly to increased fire disturbance is difficult though, because fires are often unpredictable and hard to manage. Fire recurrent or pyrophilic ecosystems, however, may be useful models for testing the effects of frequent disturbance on microbes. We hypothesized that across pyrophilic ecosystems, fire would drive similar alterations to fungal communities including altering seasonal community dynamics. We tested fire's effects on fungal communities in two pyrophilic ecosystems, a Longleaf pine savanna and tallgrass prairie. Fire caused similar fungal community shifts including a) driving immediate changes that favored taxa able to survive fire and take advantage of post-fire environments, and b) altering seasonal trajectories due to fire-associated changes to soil nutrient availability. This suggests that fire has predictable effects on fungal community structure and intra-annual community dynamics in pyrophilic ecosystems, and that these changes could significantly alter fungal function. Parallel fire responses in these key microbes may also suggest that recurrent fires drive convergent changes across ecosystems, including less fire frequented systems that may start burning more often.

Hyphae move matter and microbes to mineral microsites: Integrating the hyphosphere into conceptual models of soil organic matter stabilization

“…A full review of these stressors is beyond the scope of this review, but examples include edaphic factors such as soil water availability, pH, and salinity (Rath & Rousk, 2015; Schimel, 2018; Tedersoo et al, 2020). Thus, natural and anthropogenic disturbances leading to fungal stressors such as drought (Querejeta et al, 2009), fire (Hopkins et al, 2021), atmospheric N deposition (Moore et al, 2021), or mining (Kane et al, 2020) have the potential to alter rates of MAOM formation by altering hyphosphere communities. Importantly, environmental stressors not only lead to altered hyphosphere community composition, but also affect the physiology of individual taxa related to C use and MAOM formation (Schimel & Schaeffer, 2012).…”

Spore traits mediate disturbance effects on arbuscular mycorrhizal fungal community composition and mutualisms

“…As hypothesized, darker (low luminance) and purer colored spores (high saturation) were associated with burned sites, while grazing was associated with brighter, less pigmented spores (Figure 3). While the exact mechanism is unclear, darker coloration, especially if associated with melanin content, could help spores survive high temperatures (Cordero & Casadevall, 2017), post‐fire UV exposure (Gessler et al, 2014; Hopkins et al, 2021), or arid conditions common after fire (Deveautour et al, 2020). Lighter coloration and lower pigmentation in grazed relative to burned sites may reflect an unconsidered grazing associated stressor where whiter spore coloration is beneficial, or white pigmentation may be a conserved trait in AM fungal taxa that respond to grazing (van der Heyde et al, 2017).…”

“…For example, small, spored taxa with high sporulation rates may be beneficial in frequently grazed environments where plant hosts allocate fewer resources to root symbionts (Allsup et al, 2021; van der Heyde et al, 2019). Darker colored spores created by high melanin and/or pigment contents could help spores survive arid conditions (Deveautour et al, 2020; Henson et al, 1999), temperature fluctuations during fire (Cordero & Casadevall, 2017), or post‐fire UV exposure (observed in Hopkins et al, 2021). If fire and grazing have predictable effects on AM fungal community composition through specific spore traits, then this could have disturbance dependent implications for AM fungal mutualisms and plant communities.…”

The Effects of Fire Disturbance on Litter Decomposition and C:N:P Stoichiometry in a Larix gmelinii Forest Ecosystem of Boreal China

“…The transformation of fungi and microorganisms in the microenvironment plays an important role in the decomposition of litter [6,10,68]. After fire disturbance, the potential activity of decomposers is reduced, which will reduce the decomposition of a variety of organic compounds [11].…”

“…and abiotic factors (physical and chemical properties such as soil temperature, humidity, pH value, etc.) in the soil affect litter decomposition [10][11][12][13]. Therefore, the relationships between fire, litter stoichiometry, and decomposition become the key to boreal forest ecosystem carbon sequestration and fuel management after fire disturbance [14,15].…”