Detecting changes in forest floor habitat after canopy disturbance

Abstract

AbstractA massive ice storm hit northeastern North America in 1998, dropping more than 100 mm of freezing rain at its epicenter in southern Quebec, Canada. There has been extensive study of which trees and areas received the most damage, but the biodiversity consequences of this damage at landscape scales have not received much attention. We assessed the effectiveness of seven remotely sensed vegetation indices—Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index, Difference Vegetation Index, Renormalized Difference Vegetation Index, Atmospherically Resistant Vegetation Index, Green Normalized Difference Vegetation Index and Visible Atmospheric Resistant Index—for modeling the coarse woody debris (CWD) influx in an old growth forest reserve at the storm's epicenter; NDVI was the best predictor of CWD influx. We categorized the geospatial CWD predictions from the NDVI‐derived model to map the spatial distribution of sun‐exposed, moist‐shaded, dry‐shaded and wet CWD microhabitats on the forest floor. Moist‐shaded, dry‐shaded and wet patches of CWD were large and well connected, but sun‐exposed patches were small and sparse. Since these microhabitats affect the distribution and abundance of saproxylic insects, wood‐rotting fungi, salamanders, birds, small burrowing mammals and plant species dependent on nurse‐logs for establishment, the CWD influx from the 1998 ice storm may have revitalized local populations of these taxa through increased habitat availability as well as increased dispersal within the reserve.