Parts of a forest
The living parts of a forest include trees, shrubs, vines, grasses and other herbaceous (non-woody) plants, mosses, algae, fungi, insects, mammals, birds, reptiles, amphibians, and microorganisms living on the plants and animals and in the soil.

These interact with one another and with the non-living part of the environment - including the soil, water, and minerals, to make up what we know as a forest.

How many trees make a forest?
Forests (according to the U.S. National Vegetation Classification system) consist of trees with overlapping crowns forming 60% to 100% cover. Woodlands are more open, with 25% to 60% cover. 

Other classification systems recognize savannas, which are discussed in this Web site, as having widely spaced trees with anywhere from a minimum of 5 - 10 % cover to a maximum of 25 - 20% cover.

Many definitions of forest
Today, there are more than 250 definitions of the term "forest." These definitions differe based on the emphases or concerns of different people.

A legal definition is different from an ecological definition. The perspective of the economist differs from that of a geographer. All definitions stress the importance of trees in the system and include places where tree cover ranges from 5% to as high as 100%.