Trees thrive and are normally found in forests. The individuals on the
edges of forests tend to suffer the damage and stress of the local climate.
As one penetrates deeper into a forest the individual trees tend to become
less damaged, healthier and larger than those at the edges.
Various factors can be at work. Wind stress, less moisture retained in the soil, more competition from shade sensitive species that can not thrive under a forest canopy and such things as freezing rain all can impact the fringe trees.
In general human activity has fragmented forests and created isolated woodlots, wind breaks and fence rows. Studying and documenting the habitat of the fringe trees and isolated ones, comparing this to the interior of larger stands, would be an interresting effort. The image below shows 30 Sideroad of Amaranth Twp. passing through Maple Grove. The view looking east shows the reduced growth along the northern fringe of the stand of mostly sugar maple (Acer saccharum Marsh.). This could be one example of the phenomenon, or it could simply be new growth extending away from the main stand. It is impossible to attribute the form of a particular site to any specific causes without detailed study. Discovering how these forces interact with various species is a challanging task but probably full of satisfaction and surprise.