Ecological correlates of allelopathy in a successional system

Background/Question/Methods

Allelopathy, plant-plant interactions mediated through chemical production, has become a much more active area of ecological research.  Despite this renewed interest, we still lack basic information on the prevalence of this interaction and the types of species that may be expected to be allelopathic.  To address this research need, 64 plant species from all stages of succession were used in standardized laboratory bioassays to determine each species’ allelopathic potential.  The strength of each species allelopathic activity was then related to species life form, origin, and other plant traits.

Results/Conclusions

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 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 of allelopathic potential with other plant traits, allelopathy was positively associated with leaf water content and phosphorus content, and negatively associated with plant height, biotic dispersal, and seed mass.  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 argues that allelopathy should be included in the broader suite of plant strategies that are studied.  While the allelopathic potential results presented here needs to be verified in further studies under less restrictive conditions, this survey shows that allelopathy is a predictable trait within plant communities.