ECOLOGY: The proliferation of species common to two neighbouring biotopes, which creates very restricted ecological conditions.; FORESTRY: the effect on trees - adapted to conditions inside the forest - of the sudden exposure to new conditions (such as temperature) when clear- cutting next to them makes them the new edge of the forest; IRRIGATION, FERTILIZERS: Plants growing along the sides and ends of plots frequently are larger than those in the middle of the plot because of greater available fertility or water supply.