First-Decade Biomass and Carbon Accumulation, and Woody Community Change after Severe Wind Damage in a Hemlock-White Pine Forest Remnant

Abstract

Studies of biomass and carbon dynamics and community composition change after forest wind disturbance have predominantly examined trends after low and intermediate severity events, while studies after very severe wind disturbance have been few. This study documents trends in aboveground biomass and carbon across 10 years of forest recovery after severe wind disturbance. In July 1989, a tornado struck mature Tsugacanadensis-Pinusstrobus forest in northwest Connecticut, USA, causing damage across roughly 8 ha. Canopy tree damage and regeneration were surveyed in 1991 and 1999. Two primary hypotheses were tested, both of which derive from regeneration being primarily via the release of suppressed saplings rather than new seedling establishment: (1) Biomass and carbon accumulation will be faster than accumulation reported from a similar forest that experienced similar severity of wind disturbance; and (2) The stand will experience very little change in species composition or diversity. Estimated immediate post-disturbance (1989) aboveground live-tree carbon was 20.7 ± 43.9 Mg ha−1 (9.9% of pre-disturbance) Ten years after the disturbance, carbon in aboveground live tree biomass increased to 37.1 ± 47.9 Mg ha−1; thus for the first decade, annual accumulation averaged 1.6 Mg ha−1 of carbon; this was significantly faster than the rate reported in a similar forest that experienced similar severity of wind disturbance. The species diversity of woody stems ten years after the disturbance was significantly higher (nonoverlapping confidence intervals of rarefaction curves) than pre-disturbance canopy trees. Thus, hypothesis 1 was confirmed while hypothesis 2 was rejected. This study augments the limited number of longer-term empirical studies that report biomass and carbon accumulation rates after wind disturbance, and can therefore serve as a benchmark for mechanistic and modeling research.