A paper just published by the indefatigable Adam Young, a PhD candidate at the University of Idaho, and colleagues pulls together a lot of information about climate, forest, tundra and fire to offer a glimpse of potential future fire regimes in different parts of Alaska. By looking at fire occurrence at a multi-decadal time scale, the researchers drill down into how fire rotations are likely to respond to climate projections at a regional scale.
Exerpt from Fig. 6, Young et al. 2016. Figures in the paper not only show the observed fire rotation for 19 subregions of Alaska (Figure A2 in supplement) with 60 years of fire occurrence data, but also project future rotations under various climate scenarios (in this case a mean of of 5 global climate models).
The use of advanced statistical models to build fire-landscape response models for boreal forest and tundra reaffirms prior findings of the sensitivity of fire regime to summer temperatures and moisture deficit. However, the effect is not uniform among regions: they identify a threshold at about 56⁰ F (30-yr mean temperature of the warmest month) and another threshold for annual precipitation where fire occurrence really seems to jump. This latter finding accounts for results which project large increases in 30-year probability of burning for areas where these thresholds will be crossed in the next several decades. For example, models project the Brooks Range foothills of the North Slope, Noatak tundra and the Y-K Delta may see increases in fire 4-20x greater than historical levels. Some tundra areas are likely to experience fire frequency increase to levels not observed in the paleo record, spanning the past 6,000-35,000 years. Across most of the boreal forest, fire rotation periods are projected to be less than 100 years by end of the 21st century. This is useful information for natural resources management as well as fire protection agencies—a concise, well-researched, well-illustrated paper—put it on your summer reading list.
Young, A. M., Higuera, P. E., Duffy, P. A. and Hu, F. S. (2016), Climatic thresholds shape northern high-latitude fire regimes and imply vulnerability to future climate change. Ecography 39: 1-12. http://dx.doi.org/10.1111/ecog.02205
It has long been assumed that bark beetle outbreaks on the Kenai lead to increased fire danger, even though beetle disturbance has been shown to have mixed effects on crown fire potential, fuel profiles and burn severity in the Rocky Mountains. Winslow Hansen, doctoral candidate at the University of Wisconsin, recently published an analysis of beetle outbreaks and fire on the Kenai Peninsula between 2001-2014 (Hansen et al. 2016). He looked at effects in pure white spruce stands–where duration of beetle attacks is longer and mortality greater–and in mixed white and black spruce stands common on the northern peninsula, where attacks are less severe. His analysis indicates mixed effects: severely damaged white spruce stands did not demonstrate increased fire occurrence (instead, % canopy cover appeared to drive likelihood of burning) while the mixed white/black spruce stands didshow a positive correlation with beetle outbreaks and fire. Winston explores the reasons for this in his relatively short article: worth reading. You may remember Winslow from his previous work on beetles/fire effects and property values on the Kenai (recorded MS Thesis defense) and climate effects on fire regime (recorded 2015 presentation).
Estimates of carbon released from combustion of vegetation and organic soil during wildfires have improved dramatically over the past decade. Biomass inventory, fire effects and fire severity studies have contributed more accurate data to improve these models. (See Ottmar 2007, Brendan Rogers webinar 2015) However, figuring out the net effect of all the various effects of fire, the recovery phase and warming climate on the carbon stored in Alaska’s forests and tundra is a lot more challenging! You’d have to consider changes in burn extent and/or severity, increases in plant productivity in recovering burns, changes in species composition and what that means for productivity, changes in permafrost distribution and soil C decomposition, methane emissions and carbon fluxes in lake systems and wetlands–etc.! A team lead by Dr. Dave McGuire at UAF has taken on this modeling challenge by applying their Integrated Ecosystem Model (IEM) which includes modules for fire, permafrost, and carbon cycling. Dave recently presented an overview of their findings at an IARPC-WCT/AFSC joint webinar (presentation slides available HERE). In a nutshell, they found: 1) tundra holds 2x the carbon that boreal forest does in the same area 2) there has been a net C loss from boreal land area of about 8 Tg/yr over the last 60 years, primarily driven by large fires during the 2000’s 3) arctic tundra and SE Alaska still act as C sinks, compensating for these losses so that overall, Alaska sequesters about 3.7 Tg/yr, 4) increases in fire extent predicted with with warming climate will release even more C, but longer growing seasons and increased plant growth (as much as 8-19% increased productivity throughout the remainder of this century) with warmer climate and higher CO2 concentration in the atmosphere are estimated to offset these losses under most of the climate projection scenarios. Since this nutshell summary glosses over a lot, you should take a look at the slides and the SNAP projects page with information on scenarios and the individual models used.
A new report by USFWS Kenai Refuge fire staff (Nate Perrine) examines
areas where the 2015 Card Street fire intersected completed fuels treatments. He utilized IFTDSS (Interagency Fuels Treatment Decision Support System) modeling to analyze the treatment effect on fire behavior, and also documented post fire effects within the treated areas. This well-illustrated discussion includes recommendations for future treatments and analyses–a must-read for fire fuels specialists in Alaska! Click below to download a pdf.
The first 2016 issue of Western Forester contains a pair of short articles on the Nenana Ridge crown fire experiment and fuel break effectiveness at Funny River and the studies in progress on fuel break effectiveness in Alaska. Eric Miller (BLM-Alaska Fire Service) and Nathan Lowjewski (Chugachmiut Forester) did a nice job on these write-ups! Eric’s article gives the first published account of what happened in 2016 when wildfire challenged a 10-year old thinned fuel break in black spruce, as well as insight to the “hows” and “whys” of fire behavior in fuel breaks. Here’s a link to the issue: http://www.forestry.org/media/docs/westernforester/2016/WFJanFeb2016-2_LT3qttf.pdf
The Yukon Hot Shot Crew puts finishing touches on experimentally thinned fuel treatment blocks in June, 2007 (R.Jandt).
You might be surprised by the amount of collaboration between Alaska and Michigan-based scientists over the last 2 decades! This has been a long-standing research relationship which has spawned many useful products–including Alaska’s fire perimeter map database! Other endeavors include satellite fire detection and mapping, fuel moisture detection, improvements in fuels mapping, tundra fire research and more. Read about the history of this research relationship and its important findings and products, still ongoing with some exciting current research endeavors in a new Research Brief (LINK).
NASA’s Arctic Boreal Vulnerability Study (ABoVE) has focused a research spotlight on Alaska & Canada this year. In August, 2015, they announced 21 new projects funded for a multi-year field campaign designed to investigate the ecological and social impacts of changing permafrost, wildfires, and wildlife habitats in Alaska and northwestern Canada. Many of these involve new approaches to use remote sensing information from satellites. At least 5 funded projects involve field work in Alaska and direct involvement with the wildfire science and/or management in Alaska. Read about the new ABoVE projects at:
A multi-decadal analysis of fire in Alaskan tundra ecotones was completed using records from the Alaska Large Fire Database and an analysis of future fire potential was performed based on future climate scenarios and the Canadian Fire Weather Indices (FWI). The authors analyze tundra fire potential in different tundra areas and conclude that most areas will see substantial increase in the number of high-fire-potential days in the next few decades. This figure shows, for example, the Seward Peninsula and Southwest areas with historical (1951-2005) fire weather indices and modeled with 3 different climate projections to 2095. Although the Seward Peninsula FWI only exceeded 20 twice in the historical record (1977 & 2005), it is projected to exceed 20 much more frequently in the next decades. Read the full article: French, N. H. F., L. K. Jenkins, T. V. Loboda, M. Flannigan, R. Jandt, L. L. Bourgeau-Chavez, and M. Whitley, 2015: Fire in arctic tundra of Alaska: past fire activity, future fire potential, and significance for land management and ecology. Int. J. Wildland Fire, http://dx.doi.org/10.1071/WF14167.
Historical and projected Fire Weather Index values over Seward Peninsula, from French et al. 2015. Black represents modeled historical FWI (to 2005) and colors represent modeled future FWI for the three IPCC RCPs evaluated.