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Why Old-Growth Forests Are Important and 3 Ways You Can Help


Imagine walking in an old-growth forest where the trees sprouted before the founding of Rome.

In fact, you needn't rely on imagination: you can walk among ancient trees in many publicly accessible old-growth forests. Giant sequoias (Sequoiadendron giganteum) like the General Sherman Tree pictured above are some of the oldest living organisms on earth. The General Sherman Tree is actually only middle-aged for a giant sequoia, believed to be only about 2,500 years old. 

The old-growth forests of the California contain several world champions: the world's oldest tree (a bristlecone pine, Pinus longaeva); the world's tallest tree (a Coast redwood, Sequoia sempervirens); the world's largest tree by volume (Giant Sequoia, Sequoiadendron giganteum).

But while we still have bragging rights to these natural marvels, they represent a tiny fraction of what was once the dominant land cover across North America. 

Across the continent, we have destroyed most of the old-growth forests of North America. Logged for timber and cleared for agriculture, only about 6% of old-growth forests remain in California and the Pacific Northwest. Meanwhile, the Eastern US hangs on to less than 1% of its old growth, according to the National Commission on Science for Sustainable Forestry.

Around the world, old-growth forests include the tropical rainforests we all know about. They can also be found in the boreal forests of the sub-arctic, or the dry temperate forests of Australia. In fact, there are old-growth forests of various types on every continent except Antarctica. 

Defining old-growth forests

As with many terms bandied about by laypeople, experts disagree about the precise definition of "old-growth forest." While there is no hard and fast rule, an old-growth forest is typically characterized by:

big, old trees;standing and fallen dead trees;layers of vegetation including diverse herbaceous, shrub, undercanopy, and canopy plants/trees;diversity of plant, animal, fungus, lichen, and invertebrate species; andlack of significant human disturbance (ever, or at least within the most recent couple hundred years)

Not exactly a sound byte. 

That's okay, though. We don't need to split hairs in order to care about old-growth forests, or to take action to preserve them. Forests are dynamic ecosystems that took millions of years to evolve. They are still evolving. Even though humans have messed with just about every square mile of the earth (or so it seems), there are many areas where old-growth forests survive, or can return. 


Epiphytes and ferns grow on a tree in the layered vegetation of old growth. Audubon Corkscrew Swamp Sanctuary, Naples, FL

The importance and benefits of old-growth forest

We would not be here if it were not for our planet's forests. Through photosynthesis and respiration, trees fill the atmosphere with oxygen, build soil, and give rise to entire terrestrial food webs. Forest communities host incredible biodiversity, from microscopic creatures to enormous trees and apex predators. 

Old-growth forests sequester huge amounts of carbon from the atmosphere and store it in their wood and roots. Older trees continue to grow and store carbon even faster than young trees, contrary to previous theories. The carbon stored in forests is only very slowly released as dead trees and humus decay. Thus, even forests at and beyond the stage of ecological "maturity" are key carbon sinks and carbon fixers. Logging old-growth not only releases enormous amounts of carbon, but it also robs the planet of the oldest and best carbon-sequestering trees.

Forests also catch and hold rainwater. Much of the water falling from the sky is absorbed by tree roots and slowly filters down into the water table, as opposed to running off of bare surfaces. Forests also filter the water and cool the earth's surface, preventing quick evaporation. In places where forests have been cut down, streams and rivers run dry. Rains that used to top up drinking water supplies now cause flash floods and erosion because of the runoff. 

The forest floor is a place where leaves, branches, and other detritus fall and decay. Tree roots reach deep underground to crumble rock and draw up minerals. This process of digestion and decay builds soil. Fertile topsoil builds very, very slowly in most places, and when we cut trees and clear forests, we lose those valuable soil-building capabilities.

Along with the tree roots, complex fungal networks connect the trees in a forest. The fungal networks act as communication lines between trees. They process and deliver nutrients to trees and the trees in turn pass along sugars which the fungi need. As a community, the trees and their fungal friends support and protect one another via various communication mechanisms. For example, a pest infestation might trigger a tree to send an electrical impulse through the network. Fungal partners relay the message to other trees of the same species, which can then produce a stronger anti-pest chemical making their leaves less palatable. This symbiotic community takes time and a coherent forest to develop. Even selectively harvesting trees can interfere with the workings of the forest.

Similarly, mature and old-growth forests are home to complex ecological communities, where one creature's waste is another one's dinner. A tree grows, lives a long time, and dies. During that time, it feeds leaf eaters, houses birds and mammals, and generates oxygen. When it dies, insects, arthropods, and microscopic creatures feed upon its corpse. Other creatures feed upon the decayers. A clearing appears when the tree falls, bringing sunlight to the forest floor and providing opportunity for other herbs and trees to grow. The uneven forest floor, characterized by humps and hollows of fallen trees, collects pools of water. Food, shelter, water: basic needs for millions of species. Forests are incredibly biodiverse. 

For humans, forests also provide food, shelter, and water. Additionally, we find astonishing beauty there. Studies have shown that forests provide health and psychological benefits to people, such as lowering blood pressure and stress hormones. Read my article on forest bathing for more on the therapeutic benefits of spending time among trees. 

3 ways you can help

Here in North America, so many of us live in urban or suburban areas, we forget that the land under our feet was likely a forest at one time. Most people have never even been to an old-growth forest, particularly those of us residing east of the Mississippi. We can rekindle the connection, however. More than that, we can help protect our existing and future old-growth forests. Here are three things you can do:

1. Support the Old-Growth Forest Network


The Old-Growth Forest Network (OGFN) is a national non-profit organization whose aim is to develop a network of publicly-accessible old-growth forests in every county of the United States where forests naturally occur. That's 2,370 out of the 3,140 counties across the country. To achieve this vision, OGFN needs volunteers in every county to identify eligible forests and advocate for their addition to the network. You can sign up to be a volunteer, or support OGFN with a donation.

2. Create a "forever wild" conservation easement on your property

If you happen to own a piece of forest, or know someone who does, consider the possibility of permanent protection. By placing a conservation easement on the property with "forever wild" language, you can ensure that the forest will be protected from logging and development in the future. A conservation easement is a legal document that protects a property no matter how many times it changes hands. Find a land trust near you and ask about options. Conservation easements can be donated or purchased. You will continue to own and use the land, and retain the ability to sell it if you choose. An easement simply limits the permitted activities on the parcel.

3. Support public acquisition and protection of mature old-growth forests

Even if you don't own forestland yourself, you can actively support their protection. Many old-growth forests exist on public lands in the United States. Some are in National Parks or National Forests, while others are owned by states or even local government entities. Perhaps you know of a beautiful old forest in your community that is vulnerable to development. Find out who owns it. Then contact your local government and/or land trust to learn about possible public acquisition and protection. Even if the wild area in question has been logged in the past, it may still contain lots of big, old trees and exhibit many of the characteristics of old growth. It is still a valuable ecosystem worthy of protection. 


A number of counties in Florida have taken the proactive step of approving small, temporary property tax increases to establish a wildland acquisition fund. See Miami-Dade County's Environmentally Endangered Lands (EEL) Program as an example. With the revenue collected for just a brief three-year period, the EEL program has successfully acquired and protected over 20,000 acres of ecologically valuable land since 1990. This could be an inspiration for your own county to consider. 


Isn't it too late for disturbed areas?

Even logged-over regions have the potential to become old-growth forest again, given time. 

A highly disturbed forest, or an area that was once forest and is now an agricultural field, may never return to the same forest community it once was. When we clear land of trees, the soil washes or blows away. With that soil leave the seeds to sprout new trees and other plant species. Even where the soil remains, some seeds lie dormant for too long to be viable when conditions improve. So, if we allow that land to return to a forested state, it might not contain the seed bank necessary to regrow all of the species that it had before. 

But - and this is a big but - we humans tend to forget that our lifetimes are a blink of an eye in the timescale of a forest. Trees grow slowly. Soil builds slowly. Forests move, shift, and evolve over thousands and millions of years. We're not talking about a quick fix. 

That's no reason not to set aside as much forest as we can today, knowing that nature will find a way to rebuild and repair the damage.

Learn more - and visit an old-growth forest near you


If, like me, you thought that the old-growth forests of the Eastern United States were completely gone, I have good news! There are still examples today, and you can find one within a day's drive from nearly anywhere. Joan Maloof, the founder of the Old-Growth Forest Network, has written a fantastic book called Among the Ancients: Adventures in the Eastern Old-Growth Forests. Incredibly, she found - and personally visited - an old-growth forest open to the public in each of the 26 states east of the Mississippi River. This book is the story of her travels, with descriptions, directions, and eloquent lessons about the wonders to be found. 



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