LB 7-66 - CANCELLED - Lowland tundra plant stoichiometry is somewhat resilient following fire despite substantial and sustained shifts in community structure

Background/Question/Methods:

The Arctic is experiencing the greatest increase in average surface temperature globally, which is projected to amplify wildfire frequency/severity. Wildfire alters the biogeochemical characteristics of Arctic ecosystems. However, the extent of these changes over time—particularly with regards to plant stoichiometries relative to community structure—is not well-documented. Four years after the Yukon-Kuskokwim Delta, AK experienced its largest fire seasons, aboveground plant biomass was harvested across a gradient of burn history: unburned (“Control”), 2015 burn (“Recent Burn”), and 1972 burn (“Historic Burn”) to assess the resilience of tundra plant communities to fire disturbance.

Results/Conclusions:

Fire reduced plant biomass in the Recent Burn; early recovery was characterized by shrub and graminoid dominance. In the Historic Burn, plant biomass approached Control conditions despite a sustained reduction of lichen biomass. Altered vegetation composition likely reflects an increase in nutrient availability post-fire. Although total plant 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 persists for decades, which is associated with a transition away from N-poor lichens toward more N-rich plants.