Online seminar: The role of fungi in mediating ecosystem response to climate change

The overarching goal of our research is to improve predictions of future trajectories of climate change, by incorporating feedbacks governed by fungi. Fungi are important to consider, because they can influence nearly every aspect of ecosystem function, especially processes that occur in soils. For instance, they can conduct decomposition as they break down organic material to obtain energy and nutrients. In doing so, they release carbon dioxide as a by-product. On the other hand, to tolerate environmental stress, they can strengthen cell walls by incorporating organic compounds that form residues in soils for years to decades or longer. In this way, they can contribute to soil carbon storage.

We predicted that evolutionary trade-offs between stress tolerance-related traits versus decomposition-related traits in fungi will yield feedbacks on carbon cycling under climate change. We then tested these predictions via climate change experiments in an Alaskan boreal forest and a Costa Rican cloud forest. We found that where drought stress increased, fungi that invested more in the construction of recalcitrant cell wall compounds and less in decomposition tended to proliferate. In contrast, where climate change yielded a more moderate habitat, the reverse occurred. Altogether, fungal traits might direct negative feedbacks on carbon cycling where climate becomes more extreme for fungi, and positive feedbacks where it becomes more moderate. These opposing feedbacks would not have been apparent without an examination of trade-offs among fungal traits. Finally, these feedbacks can be incorporated into next generation ecosystem models that explicitly represent microbial traits.