Aphaenogaster rudis is considered a keystone seed disperser for myrmecochorous plants in North American forests, helping to structure understory flowering plant communities. These plants attach food bodies called eliaosomes to their seeds to attract ants and encourage dispersal. Very little work has been done to compare the phenology of fruit dehiscence and seed removal. We placed seeds of four native plant species with eliaosomes at 5 sites in the deciduous forest at Koffler Scientific Reserve in Ontario, Canada. Seeds were placed once a week for 10 weeks, and seed removal by A. rudis was measured 8 and 24 hours later. Eliaosome removal by invasive slugs was also measured at those times. We tracked fruit dehiscence of those same four species plus one more over 16 weeks at the five sites. Temperature measurements were taken at one site at KSR. We compared peaks in fruit dehiscence and seed removal, and modelled the effects of temperature and eliaosome removal on seed removal.
Results/Conclusions
Aphaenogaster rudis removed seeds of different species at different rates, yet there was also an overall pattern of removal across species, peaking in the second week of June and then remaining steady with some decline in the last weeks. Eliaosome removal was initially very low but increased steadily until the end of the experiment. There was little overlap of fruit dehiscence times between species; dehiscence was spread over the 16 weeks of the study. Peak seed removal did not correlate with dehiscence peaks. Seed removal was significantly correlated with temperature, particularly minimum daily and weekly temperature, which rose sharply to coincide with peak seed removal in the second week of June. Our research suggests that temperature has a strong effect on A. rudis dispersal phenology, and that eliaosome removal by invasive slugs may reduce seed dispersal.