Abstract:
The causes of variation in the expression of functional traits are relatively poorly understood. While functional traits may be affected by abiotic conditions, traits could potentially also be influenced by plant-plant interactions. Indeed, functional traits have been found to respond to biotic interactions in some systems. Nurse plants, in particular, may influence the expression of functional traits by the other plants, as they strongly modify microhabitat conditions, changing the fine-scale environmental conditions experienced by interacting individuals. I investigated whether functional trait values are influenced by facilitative interactions on Marion Island, using the interactions between cushion plants (known to facilitate species in harsh environments. and beneficiary species as a model system. Contrary to expectation, I found a limited response of seven leaf traits of a perennial grass (Agrostis magellanica. to the interaction with a cushion plant (Azorella selago., despite A. selago having a strong impact on the biomass, abundance and population structure of A. magellanica. Functional traits also showed limited responses to elevation, and the influence of microhabitat type (i.e. growing in cushion plants or in adjacent substrate. did not vary with elevation, despite the net outcome of the interaction between A. selago and A. magellanica being related to elevation. These results show that plant performance, as assessed by functional traits, has a limited response to the interaction with nurse species. This research demonstrates that the process through which facilitation occurs is not through shifting beneficiary species’ expression of functional traits towards more resource-acquisitive states. Therefore, other processes must be responsible for translating beneficial microhabitat modification by benefactor species into positive impacts on beneficiary species. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
