Understanding Old-Growth Forests: Where Does Banner Forest Heritage Park Stand?

Today, let's explore the fascinating world of old-growth forests—what defines them, why they're invaluable, and specifically, how Banner Forest Heritage Park in Kitsap County, Washington, fits into this cycle. Banner, a beloved 636-acre heritage park, is at the center of debates about management practices like selective thinning. Understanding its growth stage can clarify why passive approaches might be key to its future as a mature, resilient woodland.

What Is an Old-Growth Forest?

Banner Forest Heritage Park

Old-growth forests are the elder statesmen of the woodland world—ecosystems that have evolved over centuries without significant human interference, developing complex structures and biodiversity that younger forests simply can't match. In the Pacific Northwest (PNW), where Douglas fir, western hemlock, and western redcedar dominate, the U.S. Forest Service (USFS) and Washington Department of Natural Resources (DNR) define old growth not just by age (typically 150–250 years or older) but by key structural attributes.

 

These include:

• Large, Old Trees: Dominant trees with diameters at breast height (DBH) exceeding 20–30 inches, often with thick bark, broken tops, and irregular shapes from natural wear.

• Multi-Layered Canopy: A vertical diversity of tree heights, from towering overstory giants to mid-story saplings and understory shrubs, creating habitats for varied wildlife.

• Abundant Dead Wood: Large snags (standing dead trees) and downed logs that provide food and shelter for insects, birds, and mammals—essential for nutrient cycling.

• Diverse Understory: Rich plant life, including ferns, mosses, and shade-tolerant species, supporting a web of life from fungi to apex predators like owls and bears.

• Resilience and Complexity: These forests are self-sustaining, with gaps from fallen trees allowing regeneration, high carbon storage, and resistance to pests and fires due to their structural variety.

Unlike younger forests, old growth isn't "pristine" in a static sense—it's dynamic, shaped by natural disturbances like windstorms or small fires. The DNR's guide for identifying old growth in western Washington emphasizes these traits over strict age, noting that true old growth often emerges after 200 years in wet coastal forests like those in Kitsap County.

Globally, old-growth forests cover just a fraction of original extents, making their protection crucial for biodiversity, climate regulation, and cultural value. Banner Forest's Current Place in the Growth Cycle Banner Forest Heritage Park is a classic example of a second-growth forest in the PNW—vibrant but still maturing. Originally a mid-20th-century tree plantation (harvested and replanted in the 1950s–1980s), its Douglas fir-dominated stands are now 40–70 years old, placing it firmly in the competitive exclusion stage of forest development.

In this phase, trees grow densely, competing fiercely for light, water, and nutrients, leading to slower growth, stressed conditions, and a uniform canopy with limited understory diversity. According to Kitsap County's own assessments and the park's history as former DNR land transferred for recreation, Banner lacks the hallmarks of old growth: no large snags, few downed logs, and an absence of multi-layered structure.

It's a young, even-aged forest recovering from industrial planting, with high tree density (up to 280+ trees per acre) that's typical of the biomass accumulation and competitive exclusion stages. This stage is natural—forests like Banner are on a trajectory toward maturity, but they're vulnerable to interventions that could reset the clock.What It Will Take for Banner to Become an Old-Growth ForestReaching old-growth status isn't quick; it requires patience and minimal disturbance. In the PNW's moist climate, forests like Banner could transition to understory reinitiation (around 80–150 years) and eventually old growth (200+ years) through natural processes:

• Time and Natural Succession: Allow self-thinning, where weaker trees die off, creating gaps for diverse regeneration. This builds complexity without human input—studies show passive management in second-growth PNW forests leads to old-growth-like features faster than active thinning, which can homogenize stands.

• Protection from Disturbance: Avoid logging or thinning that removes key trees, as this reverts the forest to earlier stages. Banner's 139-acre wetland easement already safeguards sensitive areas, but broader passive stewardship could accelerate maturity.

• Biodiversity Enhancement: Encourage native understory (e.g., salal, ferns) and dead wood accumulation naturally, boosting resilience to pests and climate change.

• Monitoring Over Intervention: Regular, non-invasive assessments ensure progress, as DNR guidelines recommend for aspiring old-growth sites.

  
  

For Banner, with its plantation roots, full old-growth potential might take 150–250 years under passive management—faster than if thinned, which could delay structural diversity by favoring uniform regrowth.

As debates swirl around Kitsap County's restoration plans, remember: true old growth thrives on time, not timber harvests. Let's nurture Banner toward that legacy—it's not just a park; it's our future forest. If you're in Kitsap, join the conversation and advocate for passive paths to maturity!