Knowing the tree in front of you is the first step to looking after it, and trees repay the care.
The benefits of trees
Shade and cooling
A large tree shades buildings and paving and cools the air as water evaporates from its leaves. Studies of urban forests, such as those done with the Forest Service's i-Tree tools, estimate that shade from trees cuts energy use for cooling in summer and that trees can block winter wind.
Water
Tree crowns catch and slow rainfall, and roots take up water from the ground. In cities, trees can reduce stormwater runoff. In the countryside, tree roots hold soil on slopes and river banks.
Air
Leaves trap particles and take up gaseous pollutants. A Forest Service study found that trees remove a large amount of air pollution across the United States, with the largest health benefits in urban areas. Trees also take up carbon dioxide and store carbon in wood and soil.
Habitat
Native trees support birds, insects, mammals and fungi. Oaks, for example, support a very large number of caterpillar species, which in turn feed nesting birds. Standing dead trees and fallen logs provide homes for many animals as well.
People
Trees provide timber, paper, fruit, nuts, maple syrup and shade. Time among trees is also linked with reduced stress. Trees are part of the character of places: avenues, parks and village greens.
Choosing and caring for a tree
Choose a tree that is suited to your climate, soil and space, preferably a native species. Water young trees in dry weather, keep mulch off the trunk, and avoid compacting the ground over the roots. Check the health problems page for what to do when something looks wrong.