PONDEROSA PINE: PACIFIC NORTHWEST U.S.

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 and can extend down into the mountains of Utah anf and New Mexico.

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 with the fifth year or sixth year of its life, the tree begins to develop thick bark, deep roots and to shed 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.

The Ponderosa Pine life zone occurs between 7,000 and 9,000 feet in New Mexico. Tall ponderosa pine trees with open, park-like forest floors characterize this life zone. Many of the plants in this life zone, inlcuding the ponderosa pine have adaptations for surviving forest fires. Low-temperature ground fires used to be an important component of this forest ecosystem.

Ponderosa pine trees have long needles that attach to the tree in bundles of three. These trees have thick bark that peels off in puzzle-piece shapes. When heated by fire, the bark pops off the tree, protecting the tree from high temperatures. Ponderosa pines also have self-pruning branches. As the tree grows, the lower branches drop off. As a result, a ground fire cannot climb up the tree via the branches to burn the crown.

The Abert's Squirrel is a common resident of old-growth ponderosa pine forests. This squirrel has a long, bushy tail and tall, tufted ears. Abert's Squirrels rely on the ponderosa pine for food. During the summer they gather ponderosa pine nuts. During the winter, when snow covers the nut supply, the squirrels nip off the ends of the pine boughs. They peel off the needles and eat the succulent inner bark of the twigs.