Functional correlates of allelopathic potential in a successional plant community

Allelopathy, plant–plant interactions mediated through chemical production, is an active area of ecological research. Despite this widespread interest, we still lack community scale information on the prevalence of this interaction and the types of species that may be expected to be allelopathic. To address this research need, the allelopathic potential of 65 plant species from all stages of succession in the Piedmont region of New Jersey, USA, was determined with laboratory bioassays. The strength of each species’ allelopathic activity was then related to life form, origin, and fundamental plant traits. The vast majority of species tested exhibited significant allelopathic effects in the bioassays, with many of these having fairly strong effects. Overall, the allelopathic potential of species decreased with life span, roughly following the successional transitions from short-lived to long-lived herbs and to woody species. Herbaceous species on average were more allelopathic than woody species, but there was no difference between native and non-native species once life form was accounted for. In a principal components analysis, allelopathy was associated with other plant traits, but these relationships differed between woody and herbaceous species. Allelopathic potential was positively associated with plant height in herbaceous species, but negatively associated with height, leaf mass, and seed mass in woody species. These results indicate that allelopathy may be a quite common ecological strategy in plants and is equally common in both native and non-native species. The linkage of allelopathy with other plant functional traits suggests that allelopathy can and should be integrated into the broader suite of plant strategies that are studied.