Document: DAN-3-68-35

Predicting patterns of lodgepole pine serotiny across the Yellowstone landscape.

TINKER, D.B.* ¹, M.G.TURNER ¹ and W.H.ROMME ²

University of Wisconsin-Madison, Madison, WI 53706, USA ¹
Fort Lewis College, Durango, CO, USA ²

Abstract:
Lodgepole pine (Pinus contorta var. latifolia) forests dominated much of the landscape that burned in Yellowstone National Park (YNP) in 1988. Many of these trees produce serotinous cones, which do not open under normal conditions, but require high temperatures such as intense fires produce, to release their seeds. The occurrence of serotinous cones on some lodgepole pines was an important factor in determining post-fire pine seedling density in regenerating lodgepole stands. Our earlier estimates of the proportion of pre-fire serotinous trees across the YNP landscape ranged from near zero to over 80 percent. Where serotiny was high, post-fire seedling density was also high (up to 450,000/ha); where serotiny was very low, little seedling regeneration has occurred, even in stands that were previously forested. Thus, the density of serotinous cone-bearing trees is highly variable across the Yellowstone landscape, but little is known regarding the factors controlling the production of serotinous cones. We measured the percentage of serotinous trees in 63 unburned lodgepole pine stands in YNP that differed by age (<200 yr vs. >200 yr), substrate (infertile rhyolite vs. fertile andesite), and elevation (< 2300m vs. > 2300m). The percentage of serotinous trees was significantly higher (P < 0.05) in stands growing at elevations below 2300m than at higher elevations. Serotiny was also generally higher in younger stands than in older stands, although the difference was not significant. Understanding the occurrence of serotiny is necessary for predicting post-fire successional heterogeneity in YNP. The broad-scale variation in serotiny played a large role in producing a new landscape in which lodgepole pine stands of varying density will likely influence ecological processes for many years.

Keywords:

This abstract is being presented at: 3:15 PM in session:
Oral Session #35: Fire Ecology.