Life zone

The life zone concept was developed by C. Hart Merriam in 1889 as a means of describing areas with similar plant and animal communities.

[1] The life zones Merriam identified are most applicable to western North America, being developed on the San Francisco Peaks, Arizona and Cascade Range of the northwestern USA.

For example, the scrub oak chaparral in Arizona shares relatively few plant and animal species with the Great Basin sagebrush desert, yet both are classified as Upper Sonoran.

However it is still sometimes referred to by biologists (and anthropologists) working in the western United States.

Holdridge's system uses biotemperature first, rather than the temperate latitude bias of Merriam's life zones, and does not primarily use elevation.

Holdridge life zone classification scheme. Although conceived as three-dimensional by its originator, is usually shown as a two-dimensional array of hexagons in a triangular frame.