Forest Atlas Of The United States

Types of Forest Communities

Forest communities are made up of distinct assemblages of plant species. These communities are distributed quite variably across the landscape.

Certain tree species are often found together in natural forest communities. Likewise, the associated understory vegetation, as well as the wildlife that depends upon it, often occurs in assemblages that are distinctive to the composition of the tree canopy.

There are many different approaches to classifying forest communities. These classifications are useful to scientists and natural resource managers alike. However, they inevitably imply distinct boundaries, while real forest communities transition gradually from one to another, both across the landscape and over time. For this reason, classifications of forest communities evolve over time, as our understanding of these communities changes.

This chart identifies 140 forest types across the US. These are aggregated into 28 groups of similar forest types for mapping purposes. This forest community classification scheme is based upon the relative abundance of tree species, which is indicative of the amount of available light, water, and soil nutrients each use.

Distribution of forest-type groups. The map depicts the distribution of FIA forest-type groups across the contiguous US. The cyan to violet palette represents softwood forest-type groups while the red to green palette represents hardwood forest-type groups. The distribution of forest types across the US is quite variable. The majority of hardwood forest types are found in the eastern US, from the Midwest to the Northeast, as well as west Texas and the Central Valley of California. Softwood forest types are found primarily in the Southeast and throughout the western US from the Rocky Mountains to the Pacific Northwest.

explore EXPLORE WHERE TREES GROW. Select the forest type group color from the legend.Toggle between the graph and map legend buttons.

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forest type groups

This dendrogram depicts the hierarchical relationship among forest types and forest-type groups, here arranged as a circle. The diagram is read from the center of the circle moving outward. All forests can first be divided into hardwood and softwood clusters. Within each of these major clusters, forests can be further subdivided into forest-type groups. Finally, forest-type groups can be broken down into individual forest types