Rebecca Hewitt: A focus on root-associated fungi informs predictions of plant-soil feedbacks in the boreal forest after fire

In our new post Rebecca Hewitt—Assistant Professor at Amherst College, MA, USA—presents her work ‘Wildfire impacts on root-associated fungi and predicted plant-soil feedbacks in the boreal forest: research progress and recommendations’. She discusses the importance of plant-fungal interactions to cope with fire disturbance and shares her fascination for environmental research.

About the paper

We wrote a review paper that synthesizes what is currently known about plant-fungal interactions after wildfire in the boreal forest. We suggest that we can use the plant-soil feedback framework to better understand post-fire vegetation establishment, as well as diversity and function of mutualistic fungal communities in boreal ecosystems where wildfire activity has intensified with climate warming. Boreal forest trees rely on mycorrhizal fungi—symbiotic fungi associated with their roots—for acquisition of nutrients and water; yet plant-fungal interactions are often overlooked when formulating forecasts of ecosystem response to fire activity. Our team of authors has been addressing how fire impacts patterns of fungal diversity and the response of boreal tree seedling performance to mycorrhizal fungi through empirical studies. We have collectively observed the phenomena that we write about here through piecemeal field and greenhouse investigations.

Exposed root system of black spruce tree after wildfire in Interior Alaska (credit: Rebecca Hewitt)

With this paper we were excited to position our findings in the context of a broader literature review and highlight the conceptual framework of plant-soil feedbacks as a way to explore how different guilds of root-associated fungi are impacted by wildfire and, in turn, impact plant successional trajectories. We think that this paper will have broad appeal to readers who are interested in mycology, plant ecology, and scaling up for those developing models of vegetation-wildfire dynamics. 

About the research

Aspen seedling and adjacent sporocarp on burned soils after wildfire in Interior Alaska (credit: Rebecca Hewitt)

Our motivation for this paper is rooted in the exploration of the plant-soil feedback framework as a way to understand the patterns of fungal diversity, outcomes of plant-fungal interactions, and vegetation successional trajectories we observe after wildfire in the boreal forest. We have been intrigued by empirical findings that show strong shifts in the diversity of mycorrhizal fungi after wildfire—especially those that document neutral or negative impacts of endophytic and ericoid fungal guilds on seedling performance in contrast to the positive effects of ectomycorrhizal fungi.

To understand the ecological contexts where these plant-fungal interactions play out, we describe the patterns of post-fire fungal community assembly, vegetation re-establishment, and begin to link these to functional attributes of the fungal partners. We outline a roadmap for research to further investigate the utility of the plant-soil feedback framework in understanding post-fire plant-fungal relationships and link the better studied patterns of fungal diversity to function in this understudied biome.

The research priorities, from our perspective, are to address the mechanisms that underlie community assembly of root-associated fungi, the translation of fungal diversity to functional traits, the ecological importance of generalist plant-fungal associations after fire, and ultimately elucidate the biogeochemical consequences of plant-fungal interactions after fire. More broadly, we point to the importance of understanding how post-fire plant-fungal interactions may shape vegetation successional trajectories and ecosystem functions of carbon and nitrogen cycling, energy exchange, and flammability.

About the author

Rebecca Hewitt

I am an Assistant Professor of Environmental Studies at Amherst College, MA, USA. I got involved in ecological research initially through some pivotal experiences as an undergraduate student at Middlebury College, studying abroad with the School for International Training, and summer research at Rocky Mountain Biological Laboratory. I am most intrigued by the unseen world beneath our feet. Each step in my research has been to further understand the ecology of what is occurring belowground. I have endeavored to seek answers to how this might impact the patterns we can observe more easily aboveground and terrestrial feedbacks to the climate system. I am excited by the idea that improving our understanding of the rhizosphere and mycorrhizal fungi could be an important step in addressing many of the environmental issues that we face as a society. I try to keep in mind that strong sense of intrigue as an inspiration when setting out to develop research collaborations or mentor/mentee relationships. I think acknowledging that spark of fascination in understanding the environment and recognizing that in each other is an important way to foster a sense of belonging and inclusivity in the research environment.

Enjoyed the blogpost? Read the research here!

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