Contributed by Nicole Strong, OSU Extension Forester, serving Crook, Deschutes, Jefferson Counties and the Confederated Tribes of the Warm Springs
We often talk about fire-adapted forests, but what exactly do we mean? Many people wonder what happens to the trees, plants, and wildlife during and after fires, both wildfire and prescribed burns. This article presents just a few examples of ways that species in our dry forests have evolved to defend themselves, avoid fire, or work with frequent, low intensity fire to thrive.
One of ponderosa’s best defenses is its iconic (and fragrant) thick, exfoliating bark. This bark forms thick layers of puzzle-like pieces that slough off when the bark is on fire, expelling fire to the ground and off the tree. The older the tree gets, the thicker and more orange/salmon the bark color becomes. With good growing conditions, “yellow bellies” can live more than 500 years. The tree’s deep rooting habit is both strategic to optimize water and provide insulation. This tactic increases survival of the root system after fire, which allows tree to continue to take up water and nutrients, even if surface roots have been killed.
The open crown structure of ponderosa pine allows for better air flow and heat dissipation during a fire. The long needles of ponderosa pine contain a lot of moisture. Even if the needles are scorched, buds are protected by the needles, as well as thick outer scales. These buds will grow new needles after fire. A ponderosa pine can lose 90% or more of its needles in a wildfire or prescribed burn but grow new needles and rebound the following year. If by chance the fire was so hot that the tree does not make it, not to worry. That tree will become a very important snag (standing dead tree) or downed log, which are deficient in many of our forest stands. These structural components will be quickly utilized by fire and snag-adapted critters!
Quaking aspen (Populus tremuloides) needs regular fire to be able to out-compete conifers like ponderosa pine and western juniper. Aspen stands will vigorously sprout immediately after a wildfire, giving it a leg up on other, more slowly growing species. More than 50,000 suckers can sprout on a single acre of land after fire from the same underground clone. Eventually, if fire does not return, conifer trees will grow to over-top and out-compete aspen trees.
Beneath the canopy of dense and suppressed conifer stands lay a rich seed bank just waiting to be released. Regular, low intensity fire will open areas up to sun, and create the heat and nutrient-rich soil conditions that will stimulate seeds to sprout. Indian paintbrush (Castilleja spp.), scarlet gilia (lpomopsis aggregata), Oregon sunshine (Eriophyllum lanatum) and Washington Lily (Lilium washingtonianum) are just some of the wildflowers you will see after thinning, but more so after burning. And those of you who relish spring morels and boletes know that recently burned areas are the best place to find these fungi! (p.s. This Extension Forester does not recommend harvesting or eating any wild plants, roots, fungi or berries without 100% confirmation of species.)
Wildlife species have different strategies for dealing with wildfire.
Many species can outrun or fly away from a blaze; they know their home ranges pretty well and will identify the best ways in and out of harm’s way. Those who are not so quick on their feet, such as ground squirrels, frogs, or ants, will burrow deep underground or find refuge in a down log or under rocks. You will often find wildlife waiting out a fire within bodies of water, such as streams, lakes, or ponds.
Sadly, the reality is that some individuals might not survive a fire, but these animals are quickly re-entered into the food web via scavengers and predators such as coyotes, hawks, raccoons, or bears. Overall, please know that wildlife populations benefit from fire, even if a few individuals perish.
Fairly soon (within minutes to days) after a fire, wildlife will begin to return. Some species of wildlife depend on the structure and food made available from a wildfire. Black-backed woodpeckers (Picoides arcticus) for example, rely on snags (dead standing trees) created from wildfire, both for nesting and to forage insects that are attracted to these recently killed trees.
This is just a small sampling of all the fascinating ways species interconnect and interact with historic fire regimes. I invite you to continue to learn more, through personal discovery, or continued reading.