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Ponderosa Pine Woodlands

Pinus ponderosa

The coniferous forest of the refuge consists solely of ponderosa pine. Ponderosa pine associations are intermixed on refuge uplands with both steppe and soil- infuenced climax plant associations.

The single most defining ecological process in pre-settlement ponderosa pine forest in the west was a natural disturbance regime consisting of frequent, low intensity ground fires that shaped the age and size structure of forest stands and their distribution across the landscape. These fires burned through refuge ponderosa pine forest as frequently as once every 8 years.

Pre-settlement pine stands had 19 - 47 trees per acre and trees were often found in relatively even-aged clumps approximately tenth of an acre in size. Snags (dead standing trees) and down woody debris were an important component of these forests. Although a diversity of different age and tree densities were present in the landscape, the overall aspect of the forest was open and park-like, with predominately large diameter trees.
Past logging, grazing and suppression of fire has created pine stands with tree densities several times the pre-settlement condition. Large diameter trees that formally dominated this landscape constitute a small percentage of the stands. Prior to recent thinning efforts and reintroduction of fire, large portions of the refuge ponderosa pine forest had a similar age and size structure. The forest understory was dominated by decadent snowberry and a dense layer of organic debris that suppresses the growth of native bunchgrasses and forbs. Fuel loading in refuge pine stands was several times greater than the average for this forest type. The open park-like savanna of large ponderosa pine trees with an understory of bunchgrasses and forbs typical of this forest type vanished. Conditions were ripe for catastrophic loss due to insects, disease, and fire. Current restoration efforts involving mechanical thinning, piling and burning of excessive downed fuel, and following up with a low intensity understory burn has begun to restore the forest to a natural range of conditions.

Facts About Ponderosa Pine Woodlands

  • Can reach 500 years old
  • Shade intolerant
  • Fire resistant adaptations
  • Presettlement conditions included widely spaced, large diameter trees with an understory of native forbs and bunchgrasses
Last Updated: Jan 31, 2013
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