There are many reasons to be thankful for trees. The beautiful plants provide homes for animals. They also produce oxygen. Without oxygen, there would be no life on Earth. Trees also supply important products like wood, paper and fruit.

Unfortunately, only some of Earth's surface is forested. There are three different types of forests. Boreal forests are located the farthest north. Tropical forests are found close to the equator. Temperate forests grow in between these two.

Trees need specific conditions to grow. Healthy soil, sunlight and rainfall are all important. Temperature also matters. Most trees do not grow well in very hot or very cold areas. Trees need conditions that are just right.

Even then, they are not always safe. Trees face a number of threats such as pests. One serious pest is the mountain pine beetle (Dendroctonus ponderosae). It has destroyed many square miles of forest.

Both Nature and Humans can Hurt Forests

Another threat to forests is fire. Lightning strikes can set entire forests on fire. Heavy winds can quickly spread a fire. Forest fires have become a big problem in the western United States. Fires are part of the natural cycle in forests. Droughts have become more common, though. So have high temperatures. As a result, forest fires are changing. They are becoming larger and more dangerous.

Less common problems include earthquakes and volcanoes. In 1980, Mount St. Helens erupted in the state of Washington. It knocked over thousands of trees. The eruption also caused volcanic mudflows. They ripped trees from the ground and scattered them across the land.

Human activities hurt forests as well. Some forests are cut down for wood or to clear the land. Tree removal is taking place in many regions. It can be harmful to ecosystems. Cutting down forests reduces biodiversity. It destroys habitats and forces animals to move. Cutting down forests is also harmful to the native people who live in or near forests. Many of these people rely on the forest. They need it for food and shelter.

Trees do not grow equally around the planet. Some regions have more forests than others. This inequality has important effects. In areas without forests, there are no forest products to be sold. People in those areas miss out on certain benefits. They miss out on money from tourism. They also do not have the pleasure of being in the forest.