Regeneration and Seedling-habitat Relationships of the Marginal Population of Pitch Pine (Pinus rigida) After Prescribed Burning, Eastern Ontario, Canada

Abstract

Post-fire seedling establishment in relation to microsite conditions and relationships of seedlings (saplings) to older tree individuals was studied in two treatments (i.e., burned and unburned sites) in an area known as the pitch pine (Pinus rigida) ridge on Hill Island, St. Lawrence Islands National Park, Eastern Ontario. Pinus rigida is a rare tree species in Canada at the northern limit of its range. Pinus strobus (eastern white pine) and Quercus alba (white oak) are also common species of the site. The negative correlation between density of mature P. rigida trees and total canopy cover and hardwood density was con.rmed in unburned plots on the ridge. On the other hand, P. strobus density was positively correlated with those parameters. The density of P. rigida seedlings is higher (by 48%) and P. strobus seedlings lower (by 82%) in burned plots than in unburned plots. Seedling recruitment was also dependent on the occurrence of seed trees of both species. The density of P. strobus seedlings was generally higher than that of P. rigida seedlings, especially in unburned plots. The long absence of .re, high seed production of P. Strobus, and relatively low number of P. rigida seed-producing trees, which have a low amount of fertile cones, are probably the main factors in.uencing seedling recruitment on the ridge. Discriminant analysis con.rmed different seedbed requirements of both species. Pinus strobus seedlings occurred within both treatments, especially on deeper soil pro.les with thicker litter depth, although, for seed regeneration, a mineral soil seedbed or a greatly reduced organic layer was also important. Pinus rigida seedling recruitment on burned and unburned plots was comparatively higher on mineral soil, thinner litter layer, and moss and lichen cushions.