Lowland tundra plant stoichiometry is somewhat resilient decades following fire despite substantial and sustained shifts in community structure

ABSTRACT

The Arctic is experiencing the greatest increase in average surface temperature globally, which is projected to amplify wildfire frequency and severity. Wildfire alters the biogeochemical characteristics of arctic ecosystems. However, the extent of these changes over time—particularly with regard to plant stoichiometries relative to community structure—is not well documented. Four years after the Yukon-Kuskokwim Delta, Alaska, experienced its largest fire season, aboveground plant and lichen biomass was harvested across a gradient of burn history: unburned (“reference”), 2015 burn (“recent burn”), and 1972 burn (“historic burn”) to assess the resilience of tundra plant communities to fire disturbance. Fire reduced aboveground biomass in the recent burn; early recovery was characterized by evergreen shrub and graminoid dominance. In the historic burn, aboveground biomass approached reference conditions despite a sustained reduction of lichen biomass. Although total plant and lichen carbon (C) and nitrogen (N) were reduced immediately following fire, N stocks recovered to a greater degree—reducing community-level C:N. Notably, at the species level, N enrichment was observed only in the recent burn. Yet, community restructuring persisted for decades following fire, reflecting a sustained reduction in N-poor lichens relative to more N-rich vascular plant species.

KEYWORDS:

• Arctic
• tundra
• fire
• vegetation
• stoichiometry

Acknowledgments

We thank Rhys MacArthur, John Schade, Sarah Ludwig, Robert Newton, Paul Mann, and Bianca Rodriguez-Cardona for their assistance and support. We also thank the Polar Field Services for their logistical support, especially from Kevin Pettway and Robin Carroccia. We thank Alexander Barron for providing lab space. Finally, we thank Greg Fiske and Carl Churchill for providing mapping support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

SAS, SMN, and NB acquired funding for this project. SMN, NB, and SAS conceived this project. NB and SAS completed the fieldwork. NB, GP, and SAS processed and analyzed the data and drafted the article. All authors contributed to editing and revising the article.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15230430.2022.2121246.

Additional information

Funding

This work was supported by NSF grants 1915307 and 1561437 to SMN and NSF grants 2218742 and 2034323 to SAS. Additional funding from Hampshire and Smith College supported lab analysis and travel.