Case Study: Seeing the Forest for the Trees

What is So Important about Forests?

A hemispherical photograph taken through a fisheye type lens. Photo by Sassan Saatchi. Source: NASA Earth Observatory.
Forests are important natural and economic resources. Forests serve as critical indicators of the environmental health of an ecosystem, and provide us with beautiful recreational settings. People rely on the trees within forests for goods, including paper, building materials, home heating, and medicinal resources. Trees, along with many forms of vegetation, also play an essential role in providing services, such as scrubbing pollutants from our atmosphere and replenishing the oxygen supply. Approximately 33% of the United States is covered by forests today, but the state of Maine is nearly 90% forested.

Biodiversity and Healthy Forests

Kennebago River winds through the Maine Forest. Source:

Worldwide, terrestrial forests contain enormous collections of plant, animal, and other species. The quantity of resources and complexity of life in a forest is what is known as biodiversity. It can be measured on several levels, including the ecosystem level, the species level, and the genetic level. Biodiversity not only encompasses the variety of life forms found in a forest, but it is also an indicator of forest health through the ecological roles and services that the plants, fungi, animals, and microorganisms provide. A highly diverse, and therefore healthy, forest is more resilient to environmental change, such as invasive species and catastrophic fire, as well as the threats of global climate change and human encroachment.

The forests of Maine are among the most diverse in North America. They include 14 conifer, or cone bearing, and 52 deciduous, or broadleaf, trees. Since their establishment nearly 6,000 years ago, the composition and extent of forests of Maine have changed, as a result of both natural and man-made events. In the early days of European Settlement, much of the forest of Maine (68%) was cleared to make way for farming. Since the early 1900's the forest has regenerated.

Become Involved in Forest Monitoring

Teachers attend Forest Inventory Growth training in Maine: setting up a permanent plot. Source: Project Learning Tree
Monitoring forest biodiversity over time is an important component of sustainable forest management. Due to the fact that biodiversity is defined on many levels, there is no one best measure to use. More significant for policy and monitoring purposes, it is crucial to track the relative change of forest biodiversity.

Project Learning Tree (PLT) is a multi-disciplinary environmental education program for educators and students in Pre-K through Grade 12. The American Forest Foundation supports Project Learning Tree. Any citizen scientist can use the PLT forest-monitoring techniques illustrated in this chapter. To learn more about Project Learning Tree and forest monitoring techniques consult the Teaching Notes for resource links.

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