Editor's Note: This article is part of reporter Cade Barker's Wild Southwest Washington series. Find all current installments at https://tinyurl.com/ujkcvepm.
From towering Douglas firs that thrive throughout the lower elevations to mixed conifer forests stretching across the Cascade foothills, mature forests are among Southwest Washington’s most valuable natural resources.
While old-growth forests often receive the most attention, mature forests — generally those that have developed many of the structural characteristics of older forests but are still continuing to evolve — play an equally important role in supporting wildlife, protecting water quality and increasing the resilience of the region’s public lands.
Across the region, mature forests provide habitat for a wide variety of plant and animal species while serving as an important link between younger forests and the region’s remaining old-growth stands.
Large trees, multiple layers of vegetation and naturally occurring standing dead trees and downed logs create a diverse forest structure that supports birds, mammals, amphibians and insects. According to the Cascade Forest Conservancy, the forests of the Cascade Range in southern Washington are home to numerous species such as the North American beaver, black bear, cougar, elk, as well as rare, threatened or endangered species like the northern spotted owl, bull trout and Oregon spotted frog, among many others.
Mature forests also play a significant role in protecting watersheds that supply clean drinking water to communities throughout Southwest Washington, as well as habitat for many cold water fish.
The dense forest canopy helps regulate stream temperatures by providing shade, while root systems stabilize hillsides and reduce erosion. Fallen logs and woody debris slow runoff, helping retain moisture in the landscape and create healthy aquatic habitat for salmon, steelhead, amphibians and other native fish.
As climate conditions evolve, mature forests pack a unique ability to store carbon and help moderate the effects of extreme weather.
Larger trees store carbon accumulated over decades, while healthy forest ecosystems continue removing carbon from the atmosphere as the trees grow. A forest understory also retains moisture longer during the summer months, helping create cooler conditions for wildlife and reducing stress on vegetation during extended periods of drought.
Forest managers view mature forests as an important part of building resilient landscapes.
Active management in some areas, including selective thinning and prescribed fire where appropriate, can reduce hazardous fuel loads while encouraging the development of larger trees and more diverse forest conditions. In other areas, mature forests are managed to continue developing naturally to build characteristics of old-growth ecosystems over time.
For visitors, mature forests offer some of the most recognizable experiences found throughout the Gifford Pinchot National Forest and local state parks. Towering conifers, quiet hiking trails, shaded streams breaking into large waterfalls, define many of the area’s most popular forest recreation destinations.
