Edge effects on the lichen genus Lobaria in Atlantic Canadian Forests

Abstract

Clear-cut or mosaic forestry practices are known to reduce biodiversity in harvested areas, but the biodiversity in the remaining adjacent forests is also affected. Interior parts of the forest that become edge have increased light, wind, and temperature, and a decrease in moisture. Species with a narrow range of tolerance to environmental change are most affected. To better understand this "=edge effect' in the Acadian Forest, 20 mature deciduous stands in northeastern New Brunswick were examined that were adjacent to clear-cuts ranging from 6-11 years old. We used lichens as our bioindicators and selected the genus Lobaria because it is particularly sensitive to disturbance, but also common in mature deciduous forests of this region. Three Lobaria species that are known to occur in the Acadian Forest were examined: L. pulmonaria, L. quercizans, and L. scrobiculata. Canopy closure, temperature, and presence data were recorded at the forest edge and at the first occurrence of any of these three species along a transect running directly into the forest (three transects at each stand, 60 total). Our results show that the species selected have a negative response to newly created forest edges. Lobaria pulmonaria was the most tolerant to edge effects followed by L. quercizan and L. scrobiculata. The mean occurrence distance from the forest edge for all three species was 12.12 m (± 5.66). Forest managers can use these findings to better understand the impacts of clear-cutting on the biodiversity that inhabits the edges created in the residual forests.