Trees - Ponderosa Pine
The ponderosa pine is the most widely distributed species of its genus in North America. It is generally found in a sub-humid area deficient in summer rainfall. The tree reproduces through seeds produced in cones, which require 2 years to mature. The Black Hills forest is dominated by the ponderosa pine tree. Where conditions permit, other trees such as the birch, white spruce, quaking aspen, and elm also grow.
Wind Cave National Park can be divided into two major vegetation types: the ponderosa pine forest and the mixed grass prairie. Twenty-five percent of the park is tree covered. The forested area includes ponderosa pine forests and scattered groves of elm, aspen, bur oak, boxelder, and birch. These scattered groves are generally found along drainage areas. The ponderosa pine forest occupies the higher elevations in the park.
The ponderosa is an extravagant user of readily available moisture. It sends down a fast growing taproot which enables it to obtain moisture from many levels. As a seedling it also possesses the ability to withstand prolonged drought. The trees are capable of growing exceptionally fast if conditions are good for them. Because of the taproot, the trees can generally withstand high winds. When "wind throw" does occur it is often because the tree has root rot or the root systems are shallow because of the rock on which the tree is growing.
Ponderosa pines are considered fire resistant, damaged only when the fire "crowns" and sixty percent or more of the tree is destroyed. Some observers feel that a natural thinning process has largely disappeared because of organized fire protection. As a result even-aged, stagnating stands of the species have developed.
Ponderosa pines are prolific and pine seedlings grow in the shade of mature trees. If not kept in check, young trees will form exceptionally thick stands. Because of the intense competition for nutrients, moisture and sunlight, very few trees develop fully. This creates a stagnant situation for all the trees and even the grasses and forbs in the area.
Fires kept the forest in check and opened the land to grasses and other vegetation. Fires burned young seedlings so that only a few healthy ones survived to replace large trees that were dying. In this way the trees of the forest were in different stages of development and the forest was healthier.
In a healthy forest, insects, such as the mountain pine beetle, have less chance to destroy trees. The pine beetle attacks trees that are about 9 inches in diameter and are close together. In a mature, fire controlled forest, this situation rarely developed.
After a century of use and misuse the ponderosa pine forest of the Black Hills has developed into a vast area of even-aged trees. These trees are susceptible to insect infestation and destruction by fire. Also, because they are so prolific, the trees are encroaching upon the prairie and using so much of the land's moisture and nutrients that other plants can not thrive.