Edges

Edges of fragmented forests, such as those of our Seattle Parks, have been presumed to have deleterious affects on the organisms that rely on the forests.  Edge types often define what plant species can invade a given forest edge.  One clear example was in Brussels, where a 1km squared plot was surveyed, and this survey showed a strong correlation between, the study revealed that along the forest edge, at different types of edge, there were indicator species that could be used to define four different ecological groups; clear-felled, riverbanks, artificial / anthropised, and disturbed habitats.  While no correlation was found between any species and the inner forest.

This brings up, just WHY are there several species, that is, nearly 8 percent in one study, are found in significantly higher numbers along edges?  One explanation is that the alien species requires an edge as a corridor to be spread around the forest, and that perhaps some alien species cannot survive inside the established inner forest.

Most studies seek static or simplistic answers, and are left with site-specific results that may not apply elsewhere.  Data about the intensity and impact of edges on forests is urgently required, and little may be done until the mechanics of edge effects are better understood.