The Coconino National Forest

The Coconino National Forest is located in north central Arizona within the Coconino, Yavapai, and Gila Counties. (See Figure 1). The survey area encompasses approximately 2,010,782 acres (813,735 hectares) within the proclaimed forest boundaries. Approximately 165,122 acres (66,823 hectares) of other lands within unit boundaries occur as private, state or otherwise alienated lands. An estimated 150,000 acres (60,703 hectares) of wilderness or primitive areas occur within the forest.

Figure 1

The purpose of a Terrestrial Ecosystem Survey (TES) is to map and evaluate the terrestrial ecosystems in the survey area. It can be used to evaluate and adjust land uses to the limitations and potentials of natural resources and the environment. It is also useful for determining areas in which more detailed information is needed.

Climate

The survey area occurs within the north central climatological division of Arizona. In this division, the climate is highly variable as a consequence of the uneven topography and the wide range in elevation. The elevation ranges from a low of 800 meters near Verde Hot Springs to a high of 3850 meters at the top of Humphreys Peak. The climate varies from hot steppe at the lower elevations to boreal at the higher elevations.

The information presented in this section is based upon climatic station data; however, these ranges may be exceeded at either elevation extreme.

Average annual precipitation ranges from 28 to over 90 centimeters. Precipitation distribution is bimodal. The wettest season extends from July to October; a second wet season extends from December to March. In the northern and eastern portions of the forest, less than 50 percent of the average annual precipitation occurs during the low-sun half year period of 01 October to 31 March. In the southern and central portions of the forest more than 50 percent occurs during the same time period. Mean annual snowfall ranges from 0 to over 200 centimeters. However, at the lower elevations snow cover does not persist for more than a few days.
Average annual temperature ranges from 20 degrees Celsius at the lower elevations to less than -2 degrees Celsius at the higher elevations. For the month of January, mean minimum temperature ranges from -14 to -7 degrees Celsius; mean maximum temperature ranges from 0 to 12 degrees Celsius. For the month of July, mean minimum temperature ranges from 6 to 14 degrees Celsius; mean maximum temperature ranges from 21 to 45 degrees Celsius. The average date of the last spring killing freeze ranges from April 1 through July 1. The average date for the first fall killing freeze ranges from September 10 through November 1. Thus the freeze-free period ranges from approximately 250 days at the lowest elevations to less than 50 days at the highest elevations.