Old-Growth 101 – The Facts on Ancient Forests in BC

Understanding Old-Growth Forests in British Columbia

Welcome to our comprehensive guide on old-growth forests. This resource explains what old-growth forests are, why they matter, how much is left, how they differ from second-growth stands, and what’s at stake for biodiversity, climate, and communities in BC. Explore the sections below for an in-depth look at these irreplaceable ecosystems.

What is an Old-Growth Forest?
The Ecological and Cultural Importance of Old-Growth Forests
How Much Old-Growth Is Left in BC?
Old-Growth vs. Second-Growth Forests
High-Productivity Versus Low-Productivity Old-Growth Forests
Old-Growth Forests and Climate Resilience
The Stakes and the Way Forward
Take Action!

What is an Old-Growth Forest?

Old-growth temperate rainforest on Vancouver Island, BC. Old-growth forests provide unique habitat characteristics, such as nurse logs and large woody debris, not found in younger second-growth forests.

The secret ingredient in old-growth forests is time. These dynamic ecosystems have taken centuries, even millennia, to develop. They are often recognized by their towering, ancient trees, a complex understory of shrubs and saplings, and an abundance of standing and fallen dead wood. Old-growth forests evolve naturally under the influence of disturbances, such as wind, fire, and disease. When trees eventually fall over, they create canopy gaps that allow sunlight to foster a luxuriant, diverse understory of plants.

In British Columbia, old-growth is often defined by age, using criteria like 250 years in wetter coastal areas or 140 years in drier regions where disturbance rates are higher. Yet age alone does not tell the whole story. These forests display a range of structural complexities: multi-layered canopies with trees of varying ages and heights, plentiful woody debris that offers food and shelter, and a rich tapestry of epiphytes, including lichens, mosses, ferns, and fungi. In temperate rainforests, some stands have been developing for thousands of years, achieving ecological functions and biodiversity far beyond what simple age criteria can describe. This intricate blend of features makes old-growth forests ecologically irreplaceable, supporting a diversity of species that second-growth plantations simply cannot match.

The Ecological and Cultural Importance of Old-Growth Forests

Old-growth forests are ecological cornerstones and cultural treasures. These ancient ecosystems are home to diverse species, safeguard clean water, combat climate change, support tourism, and hold deep cultural significance for Indigenous Peoples.

Why Old-Growth Forests Matter

Wildlife Habitat: Old-growth forests provide vital shelter and food sources for species that are absent from second-growth forests. Black bears den in the hollow trunks of giant redcedars, while marbled murrelets and spotted owls rely exclusively on old-growth habitat. Hundreds of species new to science have also been found in the suspended canopy soils of old-growth trees.
Clean Water & Watersheds: Intact ancient forests help to stabilize stream banks, preventing erosion, reducing sediment, and filtering water clean water for people and wild salmon. Fallen logs create sheltered pools for fish, while the forest’s canopy keeps streams cool, even during heat waves.
Carbon Storage & Climate Resilience: Old-growth forests store two to three times more carbon than the second-growth plantations that replace them. Protecting even one hectare of old-growth rainforest is the equivalent of taking approximately 100 cars off the road for an entire year.
Tourism & Sustainable Economy: Old-growth forests in BC draw in visitors from around the world, boosting local economies. Port Renfrew, once a logging town, now thrives as “Canada’s Tall Tree Capital“, thanks to tourists visiting its remaining ancient forests, such as Avatar Grove.
First Nations Cultural Values: Ancient redcedars are essential for carving totem poles, house beams, and dugout canoes. The loss of large old-growth trees threatens these cultural practices. Culturally Modified Trees, such as those with stripped bark or extracted planks still living in the old-growth forest are history books telling how First Nations people have used the land since time immemorial.
Personal Health & Well-Being: Spending time in old-growth forests offers profound benefits for mental, physical, and spiritual well-being. Studies show that inhaling phytoncides—natural compounds released by trees—can boost the immune system by increasing the activity of natural killer (NK) cells, which help fight viruses and disease. The tranquil atmosphere of ancient forests also reduces stress, lowers blood pressure, and improves mood. For many, walking among towering, centuries-old trees is a spiritual experience, evoking awe, connection, and a sense of timelessness. This restorative effect is why forest bathing, a Japanese practice known as Shinrin-yoku, is gaining global popularity as a form of natural therapy.

How Much Old-Growth is Left in British Columbia?

Historical Context and Current Reality

Before industrial logging, BC likely supported about 25 million hectares of old forest. Today, only 11.1 million hectares remain—a drastic decline after more than a century of industrial logging that primarily targeted the most accessible, valuable forests, especially those in valley bottoms where the largest, oldest trees grew.

Current Snapshot

Logging Impacts: At least 10 million hectares of primary forest have already been logged, targeting the most easily accessible forests with the biggest trees first.
Quality vs. Quantity: The 11.1 million hectares that remain now predominantly include lower-productivity forests (smaller-treed areas such as bogs, sub-alpine, etc.). In contrast, high-productivity old-growth forests, essential for supporting large trees greater diversity of species, have been drastically reduced:
- High-Productivity Old-Growth Loss: Only about 415,000 hectares (roughly 3% of remaining old growth) consist of high-productivity stands.
- Best Big-Tree Forests: The rarest, most significant old-growth capable of growing the very largest trees (like the Castle Grove in the Walbran Valley) have shrunk to a mere 35,000 hectares (0.3% of the forested area in BC).
Regional Impacts:
On Vancouver Island and the southwest mainland, the situation is dire. Over 80% of the productive old-growth forests have been logged, including well over 90% of valley bottoms, where the biggest trees grow and the richest biodiversity resides. See our before & after old-growth logging maps and a shocking logging timelapse video.

The 1% Annual Logging Spin: A Misleading Narrative

Government statistics often tout that just 1% of the “Timber Harvesting Land Base” (22.3 million hectares) is logged each year (around 200,000 hectares). This figure is misleading for several reasons:

It focuses on a small percentage of an already diminished forest base.
It obscures the fact that old-growth logging still disproportionately targets the most productive and ecologically valuable stands that remain. With so little left, logging has a major impact.
The Timber Harvesting Land Base is also dynamic, shifting over time to include new areas that were previously considered “uneconomical to harvest” as the best forests steadily run out.

Biodiversity and Ecological Risk
The current status of old-growth forests in BC poses significant risks to biodiversity and ecological integrity:

Over 85% of productive forest sites in BC now retain less than 30% of their natural old-growth levels.
Nearly half of these ecosystems have less than 1% of their expected natural old-growth remaining, comparable to losing 98% of a critically endangered species, highlighting the urgent need for conservation.

Key Takeaway

While the figure of 11.1 million hectares of old-growth might sound like a lot, the real story is one of profound ecological loss. More than a century of industrial logging has disproportionately stripped away the high-productivity old-growth forests vital for biodiversity, carbon storage, and ecosystem resilience, especially on Vancouver Island and the southwest mainland of BC. Today, old-growth logging continues to target the best stands that remain.

For a deep dive on old-growth forests in BC and how much remains, see the report titled BC’s Old-Growth Forest: A Last Stand for Biodiversity.

Old-growth clearcut logging in the Klanawa Valley on Vancouver Island, BC.

Old-Growth Forests vs. Second-Growth Forests

Second-growth tree plantations do not adequately replicate the old-growth forests they’re swiftly replacing for many reasons:

Canopy and Understory

In old-growth forests, gaps in the canopy let sunlight filter through, creating a diverse understory with a wide variety of ferns and shrubs. Second-growth forests tend to have closed canopies that block out most sunlight, resulting in sparser understories.

Structural Diversity

Old-growth forests are made up of trees of different ages and heights, forming multi-layered canopies. This provides habitat for species at various levels. In contrast, second-growth forests have a single-layered canopy of trees that are all the same age class and height, with much less habitat diversity.

Woody Debris

Old-growth forests are rich in standing snags and fallen logs, which provide food, shelter, moisture, and nutrients for wildlife and fungi. Second-growth forests have far less and much smaller woody debris, greatly reducing their biodiversity and habitat potential.

Epiphytes

Old-growth forests are home to large amounts of lichens, mosses, ferns, fungi, and other flora that live on tree bark and branches (known as “epiphytes”) and as a result, they support more unique species than second-growth tree plantations.

Forest Degradation

While forests can regenerate after logging, the unique features of old-growth forests take centuries to develop — in a province where the forests are re-logged every 60 years on the Coast. As a result, old-growth forests are not a renewable resource under BC’s system of forestry and are not replicated by tree planting. Watch our video comparing old-growth and second-growth forests.

High-Productivity vs. Low-Productivity Old-Growth Forests

Old-growth forests come in many forms, and their productivity—the rate at which trees grow—varies significantly. Knowing the difference between high-productivity and low-productivity forests is key to understanding why not all old-growth forests are created equal.

High-Productivity Forests

High-productivity forests are nutrient-rich ecosystems where conditions like mild climate, abundant water, and fertile soils allow trees to grow rapidly to massive sizes. These forests are often the iconic forests people envision when they hear the word “old-growth”: towering trees reaching up to 90 meters tall and 6 meters in diameter. Found mainly in the rich valley bottoms, high-productivity old-growth forests support incredible biodiversity, sequester large amounts of carbon, and offer vital habitat for wildlife. However, these forests have been heavily logged for over a century and now make up a small fraction of their former extent. Shockingly, research indicates that only 3% of the high-productivity old-growth forests remain in BC, yet they continue to be logged.

Low-Productivity Forests

Low-productivity forests, by contrast, grow in harsher conditions such as high altitudes, rocky landscapes, or nutrient-poor soils like bogs. In these environments, tree growth is slow and often stunted, meaning these forests rarely contain large trees, even after centuries of growth. These forests are still more widespread across BC, but they don’t provide the same level of biodiversity, carbon storage, or cultural value as high-productivity forests.

Despite being less commercially valuable, misleading statistics from the BC government often combine low-productivity forests with high-productivity ones, masking the true extent of old-growth loss in the province. Doing so is like including your Monopoly money with your real money and claiming to be a millionaire.

The various forest productivity gradients of old-growth forests in BC

Old-Growth Forests and Climate Resilience

Carbon Storage and Loss

Old-growth forests store 2 to 3 times more carbon per hectare than the second-growth plantations they’re replaced with. When logged, the carbon stored in trees and soil is released, and it can take centuries for replanted forests to sequester the same amount of carbon again. Logging just one hectare of old-growth is equivalent to putting 100 new cars on the road for a year.

The Long Road to Recovery

Second-growth forests take decades to start sequestering carbon and at least 200 years to re-sequester the carbon lost when the old-growth forest was cleared. However, the current rotation age for logging is 50-80 years, meaning most of the carbon stays in the atmosphere, never to be fully recovered. And given the urgency of the climate crisis, we don’t have time to wait.

Old-Growth Forests as Climate Refuge

Old-growth forests help mitigate the effects of climate change. During extreme heat events, they provide cooler temperatures than surrounding second-growth forests, serving as climate refuges for wildlife and communities. They also moderate water flow and help reduce the severity of forest fires. As climate change intensifies, old-growth forests will become increasingly essential in buffering the impacts of heat, fires, flooding, and drought.

How Logging Contributes to Carbon Emissions

When old-growth forests are logged, carbon is released not only through the trees that are cut down but also through decomposing wood waste left in clearcuts. Carbon is also released from products made from trees—such as paper and wood—which decompose in landfills and sewage systems, creating methane. Only a small fraction of the original carbon is stored in long-lasting wood products, and even that is not long-lasting compared to the lifespan of a tree in nature.

A Global Responsibility

BC’s forests are one of the most significant carbon stores on Earth. We have a global responsibility to protect them and keep the carbon they store from being released into the atmosphere.

See an illuminating report on Forestry and Carbon in BC by Dr. Jim Pojar.

Fog drifts through an old-growth forest. These forests are important for storing vast amounts of carbon.

The Stakes and Way Forward

The depletion of productive old-growth forests has far-reaching consequences for biodiversity, climate stability, tourism, First Nations cultural heritage, and more. The stripping away of these ecosystems not only diminishes habitat for countless species but also undermines the natural processes that keep our climate in balance. In response to immense public pressure, an independent Old Growth Review Panel was convened in 2019, releasing their report titled A New Future for Old Forests. It outlined 14 critical recommendations to the BC government, including implementing immediate logging deferrals (pauses) in the most at-risk old-growth forests, prioritizing ecosystem health and resilience, and legislative reforms, to safeguard these ancient treasures. While some progress has been made on these recommendations, as of 2025, none are complete.

With only a fraction of the original high-productivity old-growth remaining and much of it under threat of logging, urgent, decisive action is needed. Their loss represents not only a decline in biodiversity and ecological resilience but also the erosion of a vital part of our natural heritage. By understanding the true state of old-growth forests in BC, beyond the misleading government statistics, we can advocate more effectively for policies that prioritize long-term ecosystem health over short-term gains. Join us in the fight to protect these irreplaceable ancient forests for our and future generations. See our campaigns page and policy recommendations for details and to learn more.

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