Fire Resilient Reforestation
Forests have an innate resilience that allows them to withstand extreme conditions. Many have incorporated fire into their seeding strategies. However, after a century of wildfire suppression, fuel loading and wildfire severity has increased, often pushing these forests too far to regenerate well on their own. Instead of a vigorous new forest, severe wildfires often allow neighboring shrublands or grasslands to spread into the gap, preventing trees from establishing. As intense, stand-replacing wildfires become more common, some fire-resistant ecosystems are at an increased risk of permanent deforestation. Where timber revenue alone doesn’t justify replanting, the carbon benefit associated with reforestation can be the difference between the re-establishment of the native overstory or a permanent conversion to grass or shrubs.
For example, ponderosa pine is incredibly resistant to wildfire. It produces a thick bark shield to protect itself from the flames, prunes its lower branches to prevent fire from climbing into the canopy, and has even developed foliage that helps to shield new buds from the heat of the flames below. These adaptations help the species to weather low- to moderate-intensity fires so that the surviving trees can seed into the newly open understory. Unlike tree species that are adapted to severe, stand-replacing fire, ponderosa pine are dependent on surviving seed trees to restore canopy cover. Unfortunately, this strategy is less effective where intense fires leave no surviving trees.
The massive historic effort to suppress fire in US forests has increased the prevalence of high-intensity fires by preventing small surface fires from removing excess woody fuels from the landscape. Small trees that would ordinarily be removed by periodic low-intensity fire bridge the gap between the understory and the dominant canopy above, allowing flames to climb crowns of the largest trees. The flaky bark that typically protects ponderosa builds up at the base of mature trees. Once ignited, these piles can smolder for days, cooking the tree at the base and killing it. Climate change only exacerbates the problem. A warmer and drier climate extends the fire season, providing a greater ignition window in these fire-prone forests. Frequent periods of low humidity and high temperatures allow fires to grow more rapidly, burn hotter, and scorch even the fire adapted canopies of dominant ponderosa. Active management is needed to restore natural fuel cycling to ponderosa pine forests, but thousands of acres burn every year before these treatments can be implemented.
The Climate Trust is assisting landowners in fire-prone forests replant after severe fire. By providing carbon funding and managing tree planting, we are demonstrating how carbon and markets can help restore these forests’ natural fire cycles and build climate resilience for the larger community and ecosystem.