Alaska fire ecology 2018: Yukon-Charley forests 14 years after the Woodchopper Creek fire

Fourteen years after the 2004 Woodchopper Creek fire in Yukon-Charley Rivers National Preserve, the shrubs under the burned black spruce had grown back to their pre-fire cover, while one paper birch site had become a pond. The National Park Service's Alaska fire ecology program reports this in its 2018 annual summary, along with its other work that year.

Figure 1: lichens 14 years after a fire. NPS photo.

The program

The Alaska region's fire ecology program provides science-based information to guide fire and land management planning, decisions and practices, in order to maintain and understand fire-adapted ecosystems in the state. In the 2018 field season it monitored Yukon-Charley Rivers, kept collecting seasonal fuel moisture samples and helped with fire research projects. Its regional fire ecologists also prepared monitoring protocols and research reports, taught classes and served on agency and interagency committees.

Re-measuring the burn

In summer 2018, fire ecologists re-measured permanent plots set up before and after the 2004 fire to record its effects on vegetation and soils at four black spruce sites and two paper birch sites. They aimed to document changes in vascular and non-vascular plant cover, tree seedling establishment, tree density by diameter class, and active layer depth and soil temperature.

Figure 2: a black spruce forest burned in 2004, shown before the fire, one year after and 14 years after. NPS photos.

• Black spruce: understory shrubs and dwarf shrubs had recovered to pre-fire cover, with Labrador tea at 42%, shrub birch at 12% and bog cranberry at 31%. Sedge cover rose above its pre-fire level, mainly tussock cotton-grass at 17%.
• Paper birch, high-severity site: hydrologic changes left a pond in the middle of the site.
• Paper birch, moderate-severity site: young paper birch saplings dominated, with bluejoint grass at 42% cover beneath them.

Figure 3: a paper birch forest at the high-severity site, shown a month, four years and 14 years after the fire. NPS photos.

Figure 4: the moderate-severity paper birch site, shown a month, a year and 14 years after the fire. NPS photos.

Seedlings

Tree seedlings matter because they form the future forest. Black spruce plots kept getting black spruce seedlings over the 14 years. Birch seedlings were common the first year after the fire, but by 14 years most had grown tall enough to count as trees. The table gives the average seedlings per square meter, which varied a lot from plot to plot.

Figure 5: average point-intercept vegetation cover by life form in the Woodchopper Creek fire plots. NPS image.

Sources

• National Park Service, Alaska Region, "Fire Ecology 2018 Annual Report Summary, Monitoring & Inventory", by Jennifer L. Barnes and Jennifer L. Hrobak (https://www.nps.gov/articles/fire-ecology-2018-summary-monitoring.htm); rewritten in hubnx's own words.