If you have not as yet, read part 1 of this post here.
11. They keep dirt in its place
A forest's root network stabilizes huge amounts of soil, bracing the entire ecosystem's foundation against erosion by wind or water. Not only does deforestation disrupt all that, but the ensuing soil erosion can trigger new, life-threatening problems like landslides and dust storms.
12. They clean up dirty soil
In addition to holding soil in place, forests may also use phytoremediation to clean out certain pollutants. Trees can either sequester the toxins away or degrade them to be less dangerous. This is a helpful skill, letting trees absorb sewage overflows, roadside spills or contaminated runoff.
13. They clean up dirty air
We herald houseplants for purifying the air, but don't forget forests. They can clean up air pollution on a much larger scale, and not just the aforementioned CO2. Trees catch and soak in a wide range of airborne pollutants, including carbon monoxide, sulfur dioxide and nitrogen dioxide.
14. They muffle noise pollution
Sound fades in forests, making trees a popular natural noise barrier. The muffling effect is largely due to rustling leaves - plus other woodland white noise, like bird songs - and just a few well-placed trees can cut background sound by 5 to 10 decibels, or about 50 percent as heard by human ears.
15. They feed us
Not only do trees provide fruits, nuts, seeds and sap, but they also enable a cornucopia near the forest floor, from edible mushrooms, berries and beetles to larger game like deer, turkeys, rabbits and fish.
16. They give us medicine
Forests provide a wealth of natural medicines and increasingly inspire synthetic spin-offs. The asthma drug theophylline comes from cacao trees, for example, while a compound in eastern red cedar needles has been found to fight MRSA, a type of staph infection that resists many antibiotic drugs. About 70 percent of all known plants with cancer-fighting properties occur only in rain forests.
17. They help us make things
Where would humans be without timber and resin? We've long used these renewable resources to make everything from paper and furniture to homes and clothing, but we also have a history of getting carried away, leading to overuse and deforestation. Thanks to the growth of tree farming and sustainable forestry, though, it's becoming easier to find responsibly sourced tree products.
18. They create jobs
More than 1.6 billion people rely on forests to some extent for their livelihoods, according to the U.N., and 10 million are directly employed in forest management or conservation. Forests contribute about 1 percent of the global gross domestic product through timber production and non-timber products, the latter of which alone support up to 80 percent of the population in many developing countries.
19. They create majesty
Natural beauty may be the most obvious and yet least tangible benefit a forest offers. The abstract blend of shade, greenery, activity and tranquility can yield concrete advantages for people, however, like convincing us to appreciate and preserve old-growth forests for future generations.
20. They help us explore and relax
Our innate attraction to forests, part of a phenomenon known as "biophilia," is still in the relatively early stages of scientific explanation. We know biophilia draws humans to water, woods and other natural scenery, though, and exposure to forests has been shown to boost creativity, suppress ADHD, speed up recovery, and encourage meditation and mindfulness. It may even help us live longer.
21. They're pillars of their communities
Like the famous rug in "The Big Lebowski," forests really tie everything together - and we often don't appreciate them until they're gone. Beyond all their specific ecological perks (which can't even fit in a list this long), they've reigned for eons as Earth's most successful setting for life on land. Our species probably couldn't live without them, but it's up to us to make sure we never have to try.
The more we enjoy and understand forests, the less likely we are to miss them for the trees.