Trees

Trees

Trees are woody plants with a distinct stem, or trunk. They are usually the tallest of plants, and their height and single main stem differentiate them from shrubs. Trees are perennials that live at least three years. Some tree species are extremely short but others may reach a height of more than 367 feet. The General Sherman Tree, a giant sequoia in California’s Sequoia National Park, has a height of 275 feet and a diameter of 37 feet. The largest trees are not always the oldest. The bristlecone pine, for example, grows to a height of only 30 feet but one specimen has been dated to be at least 4600 years old.

There are two general types of trees, angiosperms and gymnosperms. Angiosperms are flowering plants that have a seed. They include maples and oaks, which are dominant species in Kentucky. Gymnosperms, on the other hand, do not bear flowers. Their seeds lie exposed in structures such as cones or fleshy cups called arils. This group includes conifers, gingkos, and cycads.

Trees grow throughout the world, from the icy regions near the Arctic to the steaming tropical regions near the equator. They may grow along steep cliffs, in swamps and deserts, and on mountaintops at even the highest of elevations. Although trees can grow alone, most grow in strands, which consists of one species or a mixture of species. A forest is a plant community that is made up of the trees, shrubs, and herbs that cover an area.

Forests provide many social, economic, and environmental benefits. Forest provide wildlife habitat and recreational opportunities, prevent soil erosion and flooding, and help to provide clean air and water. Forests are also an important defense against global climate change. Through a process known as photosynthesis, plants exchange the oxygen that is necessary for life with carbon dioxide, the chemical most responsible for global warming. By decreasing the amount of carbon dioxide forests may reduce the effects of global warming.

In the United States, forests are threatened by extensive logging, called clear-cutting, which destroys much of the plant and animal habitats and leaves the landscape bare. Until the 1990’s, the U.S. Forest Service was directed by Congress to maximize the amount of timber harvested in order to provide jobs. In the late 80’s and early 90’s, environmentalists sued the government for violating the National Environmental Policy Act. As a result, the amount of timber harvested was reduced and foresters were directed to follow a policy known as ecosystem management.