Plant–Plant Interactions in Coastal Dunes

Biotic interactions among plants have long been recognized as important in determining community structure and dynamics (Pickett 1980). Interactions range from negative to positive and function simultaneously. The result is a balance among mechanisms that cause a gradient of potential effects. In general, it is accepted that as the abiotic stress increases, so will the importance of positive interactions, and the opposite occurs when physical stress is reduced, and the importance of competition is expected to increase (Bertness and Callaway 1994). In coastal dunes, in particular, high environmental heterogeneity generates the possibility of the occurrence of a wide variety of interactions among plants.