Silvicultural Rehabilitation of Cutover Mixedwood Stands

Abstract

We investigated rehabilitation of mixedwood stands degraded by exploitative cutting on the Penobscot Experimental Forest in Maine. Three precommercial rehabilitation treatments were applied: control (no rehabilitation), moderate rehabilitation (crop tree release [CTR]), and intensive rehabilitation (CTR, timber stand improvement [TSI], and red spruce fill planting). Crop trees (primarily red maple, paper birch, spruce, aspen, and eastern hemlock) were selected and released based on their potential for improved growth and value, spacing, and species composition. Rehabilitation reduced sapling basal area, density, and hardwood abundance and increased crop tree diameter increment. Fill planting increased spruce stocking, but many planted seedlings were browsed. Long-term projections suggested that future stand value will repay costs of moderate rehabilitation (CTR); intensive rehabilitation (CTR-TSI-planting) as applied in this study requires greater investment than can be repaid through quality and growth improvements of low-value hardwoods and softwoods. Although simulations suggested no difference in future stand value between treated and untreated stands, improvements in composition, growth, and quality after rehabilitation will facilitate later commercial thinning and shelterwood regeneration in stands which otherwise have few management options.