Effects of permanent and temporary edges on Pinus clausa (sand pine) architecture and stand conditions

Effects of permanent (i.e., maintained) and temporary edges with north- and south-facing exposures were studied in sand pine (Pinus clausa var. clausa (Chapm. ex Engelm.) Vasey ex Sarg.) scrub, an open-canopied forest type in Ocala National Forest, Florida. On edges and interiors of four stands of each type, we measured canopy tree architecture in 5 m x 100 m plots and stand density and basal area in 5 m x 200 m plots. Edge effects were modest but often stronger on south-than north-facing edges and along permanent forest roads than temporary edges of clearcuts that were allowed to regrow. Compared with interior trees, those on edges were typically shorter, retained branches lower on their boles, oriented their first branches more towards the edge, and produced more asymmetrical crowns with the long axis extending into the opening; these trends were greater on south- than north-facing edges and along permanent than temporary edges. Contrary to expectations, there were no edge effects on total basal area, dead tree densities, proportions of sand pine trees with leaning trunks, directions of lean, or angles of lean. Instead of an edge effect, most trees leaned towards the southwest, which seems related to the northeastern origin of prevailing winds and wind gusts.