Learning from Fire at Lassen

Wildfires have been burning more land, more frequently, and at higher severity levels since the mid-1980s in the western US. Some forested areas may convert to non-forest as a result. Though patchy openings in forests are ecologically valuable, extensive loss of forest means an overall loss of habitat for forest dwelling wildlife. It also means degrading water quality and losing valuable carbon storage. Because of these factors, and other impacts from large, severe fires, land managers need ways to reduce future fire severity. To do this, they are partnering with scientists like Dani Niziolek. Niziolek, who worked with the NPS Klamath Inventory and Monitoring Network as a data scientist, has been studying how fires shape forests and what strategies work to minimize forest loss at Lassen Volcanic National Park over the past several years. Based on data she and others collected for her master’s degree research before the Dixie Fire, and data she collected after the fire, she has recently published two journal articles about fire and forests in Lassen.

Conifer seedlings (lodgepole pine (Pinus contorta v. murrayana) in the foreground) growing back nine years after the 2012 Reading Fire in Lassen Volcanic National Park.

Dani Niziolek

Forest Resiliency—Some Evidence in California Montane Forests

The first journal article is about forest resiliency. It examines how well forests have been regenerating and what influenced that resiliency over the past three decades of fire at Lassen. To do that, the researchers synthesized data on conifer seedling counts from areas burned by eight fires between 1984 and 2012. They then connected those seedling counts with environmental factors that might affect regeneration and the mix of species that returned. Regeneration was more likely within 1-2 football fields of live forest patches and was also more likely with time since fire. This indicated that eventually seedling propagules will reach pretty far into a high severity burn patch but that recovery takes time—time during which forest regeneration is vulnerable to reburns. Climate conditions had less influence on the number of seedlings returning but more influence on the mix of species type. Regeneration was also common at most plots, suggesting a baseline level of resiliency. They concluded that California montane forests are resilient to prescribed fire and managed wildfire, making them useful tools to manage California forest landscapes.

Read the article:
Forest resilience and post-fire conifer regeneration in the southern Cascades, Lassen Volcanic National Park California, USA - ScienceDirect

Prescribed burning helps decrease the severity of future wildfires by lowering the fuel load. Intentional fire can also be used to backburn an area ahead of an advancing wildfire.

NPS

Fire Severity—Benefits of Thinning and Prescribed Burning

The second journal article, coauthored by Niziolek, is about mediators of fire severity in the 2021 Dixie Fire. The Dixie Fire was California’s largest single fire to date, at 374,000 ha. The study explores how previous fire and fire suppression operations during the Dixie Fire affected how severely it burned through Lassen Volcanic National Park. The study identified which types of fire suppression operations in combination with different levels of previous fire severity were most effective in reducing severity during the Dixie Fire. Suppression operations include offensive backfiring (backburning during “normal” weather conditions long before the wildfire arrives) vs. defensive backfiring (riskier, last minute backburning during “extreme” weather conditions as the fire is sprinting towards the line), fuel breaks, retardant and other tactics.

Some of the study findings surprised conventional narratives. For example, they found a smaller risk than expected from heavy-handed defensive firing in emergency situations. Though limited to the national forest and park lands in the northern footprint of the Dixie Fire, their findings point to the value of matching strategic fire suppression operations with past fire history for the best chance to reduce severe wild fires. In addition to strategic fire planning based on these findings, they also concluded that more training is needed for land managers on large fire tactics, particularly complex firing operations, to boost forest resiliency in the face of high severity fires.

Read the article:
Severity of a megafire reduced by interactions of wildland fire suppression operations and previous burns - IOPscience

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Article by Sonya Daw, Klamath Inventory and Monitoring Network
Adapted from the Klamath Kaleidoscope newsletter, Fall-Winter 2024 edition