Some neighbors are better than others: variation in associational effects among plants in an old field community

Consumer-resource interactions are often influenced by other species in the community, such as when neighboring plants increase or reduce herbivory to a focal plant species (known as associational effects). The many studies on associational effects between a focal plant and some neighbor have shown that these effects can vary greatly in strength and direction. But because almost all of these studies measure associational effects from only one or two neighbor species, we know little about the actual range of associational effects that a plant species might encounter in a natural setting. This makes it difficult to determine how important effects of neighbors are in real field settings, and how associational effects might interact with competition and other processes to influence plant community composition. 
In this study, we used a field experiment with a focal species, Solanum carolinense, and 11 common neighbor species to investigate how associational effects vary among many co-occurr...