III. CHARACTERISTICS OF LODGEPOLE PINE FORESTS

In Crater Lake National Park there exists a wide variety of plant communities presently dominated by lodgepole pine.Some communities have only a single age-class of lodgepole pine, which includes almost all the trees. Others haveseveral distinct age-classes, or have age structures that indicate that reproduction occurs more or less continuously ratherthan as a short-term response to disturbance. Some communities include other species of trees in the overstory orunderstory; others are essentially pure lodgepole pine. From this type of information we inferred what type of successionoccurs in the various forests.

Some forests are obviously seral, with lodgepole eventually being replaced by other tree species. In some seralcommunities, lodgepole pine reproduces little and the replacement is rapid, with only one generation of lodgepoleoccupying a site before the more shade tolerant trees take over almost complete dominance. Of course, some catastrophemay at any time destroy the forest, allowing lodgepole pine to return.

In one seral community the complete replacement of lodgepole pine is delayed, apparently indefinitely, by periodic lightground fires which burn the area incompletely. In two others, invasion of other tree species is slow even without fire,requiring two or more generations of lodgepole pine before the invaders gain dominance.

The lodgepole communities also vary in their understory layers, from almost absent to relatively dense. In twocommunities, at least, we think the understory plays an important role in delaying tree invasion. Managers can useunderstory composition to determine the type of forest by using the key in Appendix B; this is more accurate than themaps (Fig. 2, Appendix C) in most situations and can be applied to unmapped areas. Knowing the community, one candetermine our management recommendations from section VIII below.

The environments of the various communities are very similar in many ways. Lodgepole forests usually occur onglowing avalanche deposits on relatively gentle topography. Soils are almost all of the Steiger series. We found noevidence of serious moisture stress in any lodgepole forest. Elevations range from the lowest in the Park to over 2000 m.

However, we have identified some differences reflecting the pattern in the forest communities. Topographic basinsusually support climax lodgepole forests toward the center, the more sparse and species-poor ones being closest to themiddle. These very depauperate forests have the lowest moisture stress but do not usually include small streams andusually seem to be the farthest from outcrops of rocks other than pumice or scoria. In contrast the seral forests with thedensest ground vegetation have considerable andesite, dacite, or weathered material in the parent material or nearbyupslope, include many streams, have the greatest soil profile development but yet have the greatest moisture stress on thesaplings of lodgepole pine. Elevation correlates with some community differences, and continuity with ponderosa pineforest is characteristic of some types.

http://www.nps.gov/crla/lodgepole/lodgepole3.htmDate: 29-May-2001

CRATER LAKEReport: Lodgepole Pine—History and Management

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11/29/2011http://web.archive.org/web/20081009014057/http://www.nps.gov/archive/crla/lodgepole/lodgepole3.htm