The ponderosa's stomata are adapted to conserve and obtain moisture. The stomata are the openings in the needles through which transpiration, the exchange of gases, occurs. The needles of a ponderosa have a thick skin and breathing pores, called stomata, recessed into the skin. Another way to obtain moisture must be used. However, when there is a drought the small amount of precipitation may not be enough. Each tree needs ample space to collect water. The open space in a ponderosa forest is important. Where the soil is deep enough the roots may go down 36 feet and spread to a circumference of 100 feet around the tree. As with most plants, the roots are the primary tool for getting water. Surviving When Water Is Limitedĭuring times of drought, ponderosas are well adapted to get water and moisture whenever possible. Major conflagrations could occur but were uncommon. These fires were often ground fires that would clean up forest debris and remove shade tolerant species that might compete with young ponderosas for space and sunlight. Fire scars found in the growth rings give researchers a timeline to calculate the date of a fire. This fire record was obtained from tree core samples. Historically in the Black Hills, fires occurred in a particular area about every 27 years. The understory is kept clean of debris and shade tolerant species by periodic fires. Soon the Ponderosas take over the area and a climax forest is developed again that will maintain until the next major disturbance.Ī typical characteristic of a climax ponderosa pine forest is an open understory. The aspen seedlings can not tolerate the shade created by the Ponderosas. The aspens will continue to clone until the ponderosas begin to reseed. Cloning gives aspens a head start over other tree seedlings that start out with tiny rootlets to provide them with nutrients. Every tree growing in a stand is likely a clone. The parent rootstock produces a genetic twin or clone. Suckers are new trees that grow from the parent rootstock. In the Western United States, including the Black Hills, aspens reproduce with suckers. Individual trees may only live 30 to 50 years before they start to die. They are the first plant species to colonize a disturbed area. Grasses, shrubs and quaking aspen are introductory species. In this newly opened area other species of trees and plants will start to grow. A blow down or pine bark beetle infestation in an area can cause a break in the ponderosa climax community. If there is a disturbance in the ponderosa community, forest succession will start again from an earlier stage. A climax community is the final stage of biotic succession attainable by a plant community. In the Black Hills a ponderosa pine forest is the climax forest community. The ponderosa pine forest community has evolved with cycles of drought and fire to become home to a variety of species. Other species of pine like the Douglas fir, which is a western forest climax tree, can not tolerate the drier climate here. In the Black Hills ponderosa pines are found on dry, rocky, slopes, especially south facing slopes. Ponderosas can tolerate drier conditions. You can find ponderosas in the Black Hills, across the Rocky Mountains and westward to California. Ponderosa pine is the primary tree in the Black Hills around Mount Rushmore and are well adapted to the environment that they grow in. They have a sweet smell like vanilla or butterscotch. That is the scent of the ponderosa pine trees. If you walk through the forest in the cool of a summer evening and smell the air it may smell sweet. A group of ponderosa pine trees viewed from the ground.
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