Document: DAV-3-69-11

Constraints on forest regrowth following 19th century clearcutting and fire.

LYTLE, D.E.*

University of Minnesota, St. Paul, MN 55108 USA ¹

Abstract:
In eastern North America, forests are resilient to disturbance. If forest regrowth following disturbance is the rule, the 30 km² Kingston stump barren in northern Michigan is the exception. Prior to logging and fire a century ago, the Kingston sand plain supported a mixed white pine-eastern hemlock-beech forest. Clearcutting and fire destroyed the forest, replacing it with barrens vegetation dominated by grasses, bracken fern, blueberries, and reindeer moss. Scattered white pine, red maple, and paper birch occur on the plain, as do large white pine stumps from the pre-harvest forest. I conducted experiments and observations to understand what limits reforestation of the plain. A three-year experiment with eastern hemlock and white, red and jack pine seedlings shows that competition for water with barrens vegetation limits both seedling growth and survival; adding water or removing barrens vegetation significantly increases growth and survival. Spatial patterns of trees and shrubs on the plain may reflect this water limitation. Analysis of distances between trees, and between trees and remnant stumps, in twenty-one 625m² plots shows trees are significantly closer to both other trees and to stumps than would occur if the distribution of trees and stumps were random. Near stumps, soil temperature is significantly lower and soil moisture is significantly greater than in areas more distant from trees and stumps. Soil temperature is also significantly lower under tree canopies than in open areas. These results suggest that on drought-prone sites like the Kingston sand plain, forest resilience to disturbance is not certain. Disturbances that reduce water availability (e.g. by removing the forest canopy or destroying the forest floor litter layer) may be sufficient to limit forest regrowth for decades or perhaps centuries.

Keywords: forest, disturbance, barren, logging, fire

This abstract is being presented at: 10:30 AM in session:
Poster Session #12: Disturbance Ecology.