Ice Storm Damage Greater Along the Terrestrial-Aquatic Interface in Forested Landscapes

Abstract

Ice storms are an important and recurring ecological disturbance in many temperate forest ecosystems. In 1998, a severe ice storm damaged over ten million hectares of forest across northern New York State, eastern Canada, and New England impacting ecosystem processes across the landscape. This study investigated the spatial arrangement of forest damage at the terrestrial-aquatic interface, an ecological edge of importance to aquatic habitat and nutrient cycling. Vegetation indices, derived from satellite imagery and field-based data, were used to measure forest canopy damage across a 2045 km2 region in northern New York State affected by the 1998 storm. We investigated the forest damage gradient in the riparian zone of 13 stream segments of varying size (92.5 km total length) and 13 lakes (37.4 km of shoreline). Large streams (-fourth and fifth order), occurring in forests that received modest ice damage (<15% disturbance coverage), exhibited significantly more damage in the riparian zone within 25 m of the water than in adjacent forest sections; F(3,12) = 7.3 P = 0.005. In similar moderately damaged forests, lake shorelines were significantly more damaged than interior forests; F(3,9) = 6.4 P = 0.013. Analysis of transitions in damage intensity revealed that canopy disturbance followed a decreasing trend (up to 3.5 times less) with movement inland from the terrestrial-aquatic interface. The observed predisposition of forest to disturbance along this ecosystem interface emphasizes the role of the physical landscape in concentrating the movement of wood from the forest canopy to locations proximate to water bodies, thus reinforcing findings that ice storms are drivers of ecological processes that are spatially concentrated.