Important Tree Species Ranges
Tree species differ in responses to their environment and ability to compete with one another for nutrients. These factors strongly influence where individual tree species are found across the landscape.
The Forest Service, Forest Inventory and Analysis (FIA) program recognizes more than 400 different tree species in its survey of the forests of the United States. Included in the Forest Atlas are 24 of the most important tree species, striking a balance between deciduous and coniferous trees and representing all of the ecological divisions in the contiguous United States.
The importance of tree species within each ecological division is further understood by calculating the relative proportion of the total number of trees and tree volume for each tree species.
Using these criteria, some of the most abundant species as measured only by total volume, such as yellow-poplar and Engelmann spruce, are not included because they are not among the most “important” tree species within the ecological divisions where they occur.
In both of these charts, the outer ring represents the distribution of values across ecological divisions, and the inner ring represents the distribution of values across species within ecological divisions.
Predominantly non-forested ecological divisions are grouped together as “other” in the charts, as are minor species within each ecological division. The “other” species group is large because most forested landscapes are incredibly diverse, yet these other species add surprisingly little volume or numbers of trees.
Red maple is an important tree species in the Eastern United States.
Red Maple shows up on the charts because it is one of the top three species in four different ecological divisions, when measured by either number of trees or tree volume.
A map of species relative bundance shows the distribution of red maple across the contiguous United States, as modeled using FIA field plot data.
Although the absolute values associated with the maps differ from species to species, the highest values within each map are always associated with the darker colors. The outlined species range map shows the species historical range as mapped by E.L. Little in the 1970’s.
Redwood is an example of an important species along the Pacific coast.
Redwood is included in the Forest Atlas because it is the top-ranked species by tree volume and second-ranked species by number of trees in the Mediterranean Division.
Like the Red Maple example, the accompanying map depicts the abundance and distribution of Redwood across the contiguous United States, modeled using FIA field plot data.
EXPLORE WHERE DIFFERENT TREE SPECIES OCCUR AND THEIR TREE NUMBER / VOLUME RELATIONSHIP.
Select a species from the scroll bar to investigate this for different tree species. What is the story that you would tell about Balsam Fir?