27 Facts About Trees and Forests

That’s right: rainforest plants are used in some of the world’s most important, life-saving medicines. More discoveries are made every year, but many rely on access to healthy forests.

As well as saving people’s lives, these medicinal plants are worth a staggering US$108 billion a year. So if anyone asks "why are rainforests important?" Here's one reason — and it's just scratching the surface!

When it rains, trees absorb stormwater into their roots and leaves, reducing erosion and flooding. Later, their leaves release it back into the air through transpiration, producing a powerful cooling effect that affects local microclimates. 

Trees reduce the need for carbon emissions from heating and cooling by helping to regulate air temperature. Well placed trees can reduce air conditioning costs by 30% and heating costs by as much as 50%.

The total forest area is 4.06 billion hectares, and approximately 1/2 of that forest area is relatively intact. Around 1/3 of that is primary forest, or forests with no visible indications of human activities and ecological processes that are not significantly disturbed. 

And it’s estimated that one hectare (2.47 acres) can contain over 750 types of trees and 1500 species of higher plants.

Nearly a third of that loss, 3.8 million hectares, occurred within humid tropical primary forest, areas of mature rainforest that are especially important for biodiversity and carbon storage.

Trees can absorb an average of 22 pounds of CO2 per year for the first 20 years of life. A typical passenger vehicle emits about 4.6 metric tons of carbon dioxide per year — so it stands to reason that vehicle owners would need to plant 460 trees to offset the average transportation impact. 

Trees release oxygen when they harness solar energy to transform carbon dioxide and water into glucose. They use some of the resultant oxygen when they break some of the glucose back down to power their metabolisms. But on average, trees produce more oxygen than they use.

As one tree is joined by others to form a stand, biodiversity will gradually grow. Once the stand approaches 100% forest cover, endangered and at-risk species like large predators and deep forest birds begin to appear, building species richness.

This in spite of the fact that the planet lost more than 1.33 million square kilometers between 1982 and 2016, mostly in the tropics. But it comes with a catch. These new trees, many of which are growing in tree plantations, are not a perfect replacement for rich and diverse primary forests.

But forests are not equally distributed around the globe. More than 1/2 of the world’s forests are found in only 5 countries (the Russian Federation, Brazil, Canada, the United States of America and China) and 2/3 (66%) of forests are found in 10 countries.

Primary forests, especially in the tropics and savannahs where deforestation is particularly intense, are old growth forests teeming with biodiversity. All of that is lost when these areas are cleared. 

Large-scale commercial agriculture (primarily cattle ranching and cultivation of soybean and oil palm) accounted for 40% of tropical deforestation between 2000 and 2010, and local subsistence agriculture accounted for another 33%.

This is down from 16 million hectares per year in the 1990s. And while this is good news, we’re still losing forests at a blistering rate. With daily evidence that climate change is gathering momentum across the globe, we can’t afford to keep losing them. 

The majority of tree species are angiosperms with enclosed seeds and broad leaves that change color and die every fall. They include oaks, maples and dogwoods and are deciduous. Gymnosperm trees, or those with unenclosed seeds, include species like pine, cedar, spruce and fir and are usually evergreen.

These families are, in order of magnitude: Leguminosae, Rubiaceae, Myrtaceae, Lauraceae, Euphorbiaceae, Malvaceae, Melasomataceae, Annonaceae, Arecaceae and Sapotaceae. 

This means that they only exist in one area. Endemic tree species are particularly threatened by deforestation, because if their habitat is destroyed, they’re likely to become extinct. 

With enough oxygen to support humans and the other oxygen-dependent life forms we share the planet with.

For those living in poverty, trees provide an important safety net if crops fail or diseases spread, preventing heads of households from being able to work. 

And in many countries in the developing world, people draw on fuelwood to meet as much as 90% of their energy requirements. As you might imagine, this contributes to deforestation, and is part of why it’s so important to include local communities in reforestation projects.

That’s because indigenous peoples hold to their traditional ways of life and draw on ancestral knowledge to tread softly in the natural world. 

In a recent study, it was found that people are paying an estimated 8 billion visits a year to these areas — greater than the total global population. 

This is partially due to historically heavy settlement in Europe, and accompanying land-uses like logging and intensive agriculture. Europe also has less total land area. 

If tropical deforestation were a country, it would rank third in carbon dioxide-equivalent emissions, only behind China and the United States of America. In fact, tropical forests are net carbon emitters due to deforestation. 

For this reason, it may make more sense to call the Amazon Earth’s air conditioner, rather than its lungs. 

Crucially, a majority of this carbon resides in forest soils, anchored by networks of symbiotic roots, fungi and microbes. Because of this, forests are typically considered carbon sinks (places that absorb more carbon than they release).