Congrats to Kate Hayes, who’s project, “Evaluating Flammability of Reburns in the Boreal Forests of Interior Alaska,” was selected for funding. Kate’s work is really fascinating, looking at how a sustained increase in fire frequency will shape future landscapes - and importantly, looking beyond first order feedbacks to longer term mechanisms. The work will go on for a couple years funded by the Joint Fire Science Program
From the proposal
Project Abstract:Temperatures in high-latitude environments are rising quickly, leading to increases in the frequency and intensity of wildfires (Kasischke et al. 2010). This trend is especially important in the boreal where fire return intervals have shrunk from between 100-300 years to often less than 20 (Zoltai et al. 1998, Brown & Johnstone et al. 2012, Caplat & Anand 2009, Johnstone & Chaplin III 2006). Shortening fire intervals have led to an increased presence of early to mid-successional deciduous species, with birch (Betula neoalaskana), alder (Alnus crispa), aspen (Populus tremuloides) and willow (Salix spp.) becoming dominant in stands previously dominated by black spruce (Picea mariana) (Hoy et al. 2016). Boreal deciduous species are considered less flammable than black spruce, so an increase in deciduous species has been hypothesized to reduce overall landscape likelihood of burning, creating a negative feedback loop (Astrup et al. 2018). The presence of deciduous species has been invoked as a landscape management solution to arctic and boreal warming, based on paleoecological evidence of declining fire activity found alongside increases in the presence of birch (Kelly et al. 2013, Brubaker et al. 2009). However, historical forest compositions were slightly different: past boreal environments were dominated by birch alone, while recent studies have found alder, aspen, and even willow in dominant quantities (Higuera et al. 2008). Furthermore, preliminary work (Hayes et al, in prep) demonstrates that fuel structures change dramatically across a 1-3 short interval fire gradient, with three burns resulting in more open, shrubby structure with increased willow. This indicates that paleoecological studies are not a perfect analogue for modern change, and that specific modern empirical landscape flammability data is required to inform future management directions.
Current consensus holds that an increasing presence of deciduous species could act as a negative feedback to increasing fire, but that idea is based on the assumption that deciduous species lower landscape flammability. The rise in reburns across the state of Alaska is creating novel deciduous forest structures and compositions, configurations that may behave differently than paleoecological analogues and modern expectations.
Quantify landscape flammability across a gradient of fire histories in the boreal forests of Interior Alaska.
This research will help answer fundamental questions regarding the flammability of emerging boreal landscapes and will contribute directly to fire management strategies in Interior Alaska. The first benefit from this work will be specific standardized measurements of flammability of dominant boreal species across growth forms. These measurements will help resolve how landscape flammability may change with emerging changes to boreal forest structure as a result of multiple short interval fires.
The second benefit from this work will be quantification of fuel loads and structures across reburns in Interior Alaska. This dataset will include paired measurements of fuel type, quantity and spatial arrangement that can be analyzed against fire history, topography and regional climate. Quantification of the flammability of this emerging and apparently novel forest structure that results from long-term exposure to short interval fires is novel. The dataset produced will benefit both researchers and managers interested in changes occurring in boreal systems. Insights gained from this research will contribute directly to fire management: by knowing the relative flammability of different forest structures and compositions in reburned boreal forest, managers can better make decisions about restoration via prescribed fire, wildfire suppression and the dynamics of fire and vegetation.
The deliverable will be an actionable policy brief given to the Alaskan fire management community..