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What is a Forest?

Nifa Author
Daniel Cassidy, National Program Leader

The United Nations designated March 21 as the International Day of Forests. Over 31% of the Earth’s land area is covered by forest, nearly 10 billion acres.  Forests are composed of about 60,000 known species of trees, making them some of the most complex ecosystems in the world. 

Merriam-Webster defines a forest as “a dense growth of trees and underbrush covering a large area.” It’s an acceptable definition, but it does not capture the importance of the crucial role forests play in providing important ecological, economic, social and health benefits — and why NIFA funds several programs that support this critical national resource. 

In the United States, forests capture and filter water for 180 million people and coffee forests are the source of the world's most popular beverage. Forests are the resources needed to produce the paper for your newspaper, lumber for your homes and the oxygen we all need. They capture carbon to help mitigate climate change and stabilize erosion to protect our valuable soils.  

Promoting Health in Surprising Ways 

Healthy forests produce healthy people. Forests provide resources for nearly 50,000 different medical purposes. Our diets are even influenced by forests. According to the Food and Agriculture Organization of the United Nations (UN FAO), children who often visit forests have a higher dietary diversity compared to those who do not take those adventures. 

Need to reduce stress, lower your blood pressure and slow your pulse rate? Forests have been shown to help with that. Expose yourself to a forest and experience squirrels chasing each other, fresh fruits such as blackberries and apples, or take a long quiet walk under a cathedral ceiling of tall trees and be serenaded by the songs of birds and the babbling of a brook.     

Supporting an Impressive Amount of Biological Diversity 

Forests are as diverse as the people they support.  

There are grand hardwoods — such as the mighty oaks — that produce the crunchy leaves in the fall. There are softwoods like the giant sequoia as well as pines and firs we use to decorate the winter holiday season and mixed forests with both hardwoods and softwoods that provide very complex ecosystems. 

They can be wetlands or they can be found in the dry desert regions. Forests can be highly managed by professional foresters or left natural and wild to develop on their own. 

Under Threat from Climate Change 

They are also under extreme pressures, such as the wildfires we have seen in the western United States and the long-term effects of drought in the Southeast. Deforestation, the purposeful clearing of forests for farmland or residential purposes, has resulted in the loss of 27 million acres per year globally. That is roughly the size of Kentucky.  

Insects, such as the southern pine beetle or the gypsy moth, damage more than 35 million hectares annually.  

These are just a few of the reasons to protect our global forests. 

I hope this gives a more complete answer to “What is a forest?” It is not entirely complete, and the answer certainly is complex.  

A forest could be a small acre that fuels the imagination of children, or it could be a stretch of land with the grandeur of the Great Smoky Mountains. Forests are what you make of them. It is how you spend your time with them and how they touch you emotionally. 

Now if you forgive me, there is a treehouse in my forest that I have not visited in a long time. 

For more information and questions, please contact Dr. Daniel Cassidy, national program leader for forest research at the USDA National Institute of Food and Agriculture.  

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