Different Ecosystems:

Tallgrass Prairie: Midwest | Chaparral: California & Southwest | Ponderosa Pine: West | Douglas Fir: West | Loblolly & Shortleaf Pine: South | Jack Pine: Great Lakes States

Ponderosa Pine: Western United States

Ponderosa pine can exist as one component of a mixed forest, particularly in combination with Douglas-fir, or as a pure forest type. The typical surface cover in a ponderosa pine forest is a mixture of grass, forbs and shrubs. This forest community generally exists in areas with annual rainfall of 25 inches or less. Extensive pure stands of this forest type are found in the southwestern U.S., central Washington and Oregon, southern Idaho and the Black Hills of South Dakota.

fire in the woods

Lake Roosevelt National Recreation Area, Washington

For approximately the first five years of their life cycle, ponderosa pine seedlings must compete strenuously with grass cover for survival and are very susceptible to fire. But, beginning in the fifth year or sixth year of its life, the tree begins to develop thick bark and deep roots and sheds its lower limbs. These factors increase its ability to withstand fire and decrease the possibility of a fire climbing to the crown. Furthermore, a thick bed of needles is deposited on the ground, suppressing grasses in the vicinity, thereby controlling the type of fuel available for burning and the type of fire that the tree may need to endure in the future.

Conifers, including ponderosa pine, are most flammable in the spring when their old needles are dry and new needles have not yet grown. In the fall, when the needles have dried out, conifers again are susceptible to fire.

Fire in ponderosa pine forests, as in Chaparral communities, serves to replace older plants with younger ones of the same species. Historically, fires in ponderosa pine communities burned naturally on a cycle of one every 5- to 25-years.

map with blue area indicating panderosa pine areas

Range of ponderosa pine in the Western United States.

Prescribed burning is applied with slightly greater frequency and regularity, keeping in mind that a fire that is ignited too early will not have sufficient fuel to be effective. Similarly, a fire ignited too late in the cycle may potentially develop into a high-intensity fire.