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Harvard Forest Research Project 2024
- Title: Hurricane Manipulation Experiment
- Principal investigator: Audrey Barker Plotkin (aabarker@fas.harvard.edu)
- Institution: Harvard Forest
- Primary contact: Audrey Barker Plotkin (aabarker@fas.harvard.edu)
- Team members: David Foster
- Abstract:
Wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. In 1990, we initiated a large hurricane simulation experiment in a 0.8-ha manipulation (pulldown) and 0.6-ha control area of a maturing red oak - red maple (Quercus rubra and Acer rubrum) forest in New England. We toppled 276 trees in the pulldown, using a winch and cable, in the northwesterly direction of natural treefall from major hurricanes. Eighty percent of canopy trees and two-thirds of all trees >5 cm dbh (diameter at breast height) suffered direct and indirect damage. Based on the patch size and disturbance magnitude, we expected pioneer tree and understory species to drive succession.
The first decade of analyses emphasized tree seedling establishment and sprouting by damaged trees as the dominant mechanisms of forest recovery in this extensive damaged area. However, despite 80% canopy damage and 8000-m2 patch size, surviving overstory and advance regeneration controlled longer-term forest development. Surviving oaks are still a major part of the stand's structure and biomass. The new cohort of trees is dominated by black birch advance regeneration. There were shifts in understory vegetation composition and cover, but few species were gained or lost after the first decade or so. Stand productivity rebounded quickly (litterfall recovered to pre-disturbance levels in six years), and woody biomass has nearly recovered after 30 years. However, we predict that basal area in the pulldown will lag behind the control for decades to come.
This controlled experiment showed that although the scale and intensity of damage were great, abundant advance regeneration, understory vegetation, and damaged trees remained, allowing the forest to resist changes in ecosystem processes and invasion by new species.
