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Forest Resiliency

Posted by Hannah Meganck on September 18, 2017

Restoration must take into account all of the contributing stressors

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If you visit the Ochoco, Umatilla, and Wallowa-Whitman National Forests, it doesn’t take long to find areas where forest conditions are dominated by dense stands with thick ladder fuels.  How did these forests get to be so overcrowded?

Many of these areas have become overcrowded largely due to past wildfire suppression. We have suppressed wildfires so effectively that dry forests have become overcrowded with close-canopied forest stands dominated by smaller diameter, young trees. Fire suppression has also led to conifers spreading into aspen stands and historically non-forested areas.

Another contributing factor to forest health is climate change.  Climate trends in northeast Oregon and Washington are leading to extended late season drought and longer wildfire seasons.  Drought, especially prolonged or severe drought, can create increased stress in forest ecosystems.  When you combine extended hot weather conditions with overcrowded, unhealthy or stressed trees, these forests become unnaturally susceptible to insect attack and severe wildfires.

When these forests catch fire they often burn hotter and kill more vegetation compared to the past, where forest conditions were more resilient. The effects of large and severe wildfires not only impact communities, but also a variety of resources dependent on healthy forest ecosystems. Tree mortality impacts forest growth, how much carbon is captured and stored, the health of critical wildlife and fish habitat, water quality, and even the safety of recreational activities such as hiking and hunting.

If we want to move our forests toward healthier, sustainable conditions that are resilient to natural disturbances, we must do something to return the vegetation to more natural conditions.  Forests that are in a natural condition are more resistant to insect mortality, less likely to be completely burned, and reduces the risks to nearby homes and facilities from unwanted fire impacts. We can do this by reducing stand density across large landscapes (thinning the number of trees on an acre), adjusting species composition (altering the species of trees and other vegetation growing on a site), and creating more natural forest patterns.

Thinned stand in Ochoco National forest. Photo credit: USFS
Thinned stand in Ochoco National forest. Photo credit: USFS
This doesn’t mean eliminating fire. Dry forest landscapes have evolved with fire for tens of thousands of years.  Fire disturbance is a natural and needed component for a dry forest to function properly.  So, some fire is wanted and necessary to maintain landscapes in a more natural and resilient condition. Fire can be a useful tool.

There are, however, many locations where fire is unwanted - whether it is natural or not.  In these areas, land managers must conduct specific treatments designed to reduce the risk to people, their homes, and property.  Some of these treatments include reducing surface fuels by removing excessive amounts of brush, shrubs, and trees.

It is unclear exactly how climate change will affect the Blue Mountains over the coming centuries, but we do know that some tree species are more resistant to drought and fire than others. By managing forest density and composition, forest managers help support the growth of desired forest vegetation that will be able to persist under changing climate conditions. These treatments will reduce or mitigate drought-related stress and improve forest resilience. While fewer trees might not necessarily use less water than more trees, active management can create healthier forests that are better able to resist drought stress and insect attack.

The Forest Resiliency Project provides an opportunity for land managers to take a landscape-approach to creating a more resilient ecosystem. These approaches are a first step, and we must continue to take greater action to restore our landscapes, increase fire’s beneficial effects, and reduce the exposure of homes and sensitive habitats to the unwanted effects of severe wildfires.

Do you want to know what others are saying about this project? Find out more by visiting the public reading room. Additionally, you can find notes from recent public engagement sessions on the project public engagement website.

This article series Features from the Blue Mountains Restoration Strategy is brought to you by Sustainable Northwest and the U.S. Forest Service Blue Mountains Restoration Strategy Team.