Physical Stress and Positive Associations Among Marsh Plants

The contribution of positive interactions such as facilitations and mutualisms to the structure and organization of natural communities has received little recent attention. Here we show that distribution patterns of New England salt-marsh plants are strongly influenced by facilitative associations among neighboring plants. Positive interactions among marsh plants appear to be the simple by-product of neighbors buffering one another from potentially limiting physical stresses and thus only occur in physically harsh habitats. Positive associations such as these are likely common but unappreciated forces in harsh environments that have been largely overlooked by contemporary ecologists because of their preoccupation with competitive phenomena.