Friday, August 6, 2010

PS 102-106: The roles of fire and landform in controlling stand dynamics of high elevation pine ecosystems in northeastern West Virginia

Lauren F. Howard, Daniel Brophy, and Maria Stelacio. Arcadia University

Background/Question/Methods

Successful conservation of rare high elevation (> 1200 m) pine-dominated ridges in northeastern WV depends on understanding the natural role of fire. We hypothesized that periodic fire is essential for regeneration and structures communities on hillsides and plateaus, but pines can persist without periodic fire on environmentally stressful cliffs and sphagnum bogs. We sampled 44, 400-m2 sites, paired on gradients from a cliff or bog to 100-200 m downslope or upslope, respectively. We measured tree diameters, extracted ~12 increment cores per site, estimated plant percent cover, counted pine seedlings < 1 m tall, and recorded physical evidence of fire, including bark charring and soil charcoal.

Results/Conclusions

Fire evidence was found at 100% and 93% of plateau and hillslope sites, and at 89% and 43% of cliff and bog sites. Of 258 pitch pine seedlings encountered, 42% occurred on cliffs and 53% in bogs, indicating a lack of regeneration on plateaus and hillslopes and supporting our hypothesis. Cliff and bog sites were older on average than plateaus and hillslopes (90th percentile of tree age was 101 vs. 82 years), however this was not always true for individual site pairs. The standard deviation of tree age was not higher at cliff and bog sites where multigenerational stands were expected (28 years vs. 27 years at plateaus and hillslopes). Preliminary dendrochronological analysis of radial growth patterns shows an individualistic disturbance history for each site that does not consistently support our original prediction of even-aged stands on hillslopes and multigenerational stands on cliffs and bogs.