Assessing Burn Status and Moisture Regimes as Drivers for Variability in Shrub Phenology in the Yukon-Kuskokwim Delta

The Yukon-Kuskokwim Delta (YKD) of Western Alaska experiences frequent low-intensity burns that impact plant species composition on a broad scale, but the intricacies of species-specific phenology in this area are not well known. Our goal is to understand how the phenologies of five ubiquitous shrub species (Betula nana, Empetrum nigrum, Rhododendron subarcticum, Vaccinium uliginosum, Vaccinium vitis-idaea) respond to burn status and moisture regimes. Given the unusually dry summer, highland sites are exhibiting signs of stress (red, brown, and crinkled leaves), which will likely contribute to delayed highland plant phenophases with the exception of early senescence. Burn status effects are most notable when comparing lowland burned and unburned sites, where the phenophases of burned sites are advancing at faster rates, potentially as a result of increased nutrient availability. Unburned, highland sites will most likely reach senescence first because of the smaller soil nutrient pool and reduced access to water. As climate change increases the frequency of fires and alters water availability across the YKD, understanding how plant species respond to burn conditions and moisture regimes allows us to better estimate future aboveground biomass and the influence of climate change on carbon source and sink potential.