Premise of the Study: Patterns of fruiting phenology in temperate ecosystems are poorly understood, despite the ecological importance of fruiting for animal nutrition and seed dispersal. Herbarium specimens represent an under-utilized resource for investigating geographical and climatic factors affecting fruiting times within species, patterns in fruiting times among species, and differences between native and non-native invasive species. Methods: We examined over 15,000 herbarium specimens, collected and housed across New England, and found 3159 specimens with ripe fruits, collected from 1849–2013. We examined patterns in fruiting phenology among 37 native and 18 invasive woody plant species common to New England. We compared fruiting dates between native and invasive species, and analyzed how fruiting phenology varies with temperature, space, and time. Key Results: Spring temperature and year explained a small but significant amount of the variation in fruiting dates. Accounting for the moderate phylogenetic signal in fruiting phenology, invasive species fruited 26 days later on average than native species, with significantly greater standard deviations. Conclusions: Herbarium specimens can be used to detect patterns in fruiting times among species. However, the amount of intraspecific variation in fruiting times explained by temporal, geographic, and climatic predictors is small, due to a combination of low temporal resolution of fruiting specimens and the protracted nature of fruiting. Later fruiting times in invasive species, combined with delays in autumn bird migrations in New England, may increase the likelihood that migratory birds will consume and disperse invasive seeds in New England later into the year.
Bibliographical noteFunding Information:
The authors thank the collectors and staff that provided access to herbarium specimens for this project, including staff at Harvard University Herbaria, George Safford Torrey Herbarium at the University of Connecticut, University of Maine Herbaria, Hodgdon Herbarium at the University of New Hampshire, Yale University Herbarium, and the University of Massachusetts at Amherst herbarium. We thank two anonymous reviewers, Abe Miller-Rushing, Lucy Zipf, Caitlin McDonough MacKenzie, and Pam Templer for their helpful comments on this manuscript. This material is based on work supported by a National Science Foundation Graduate Research Fellowship to A. S. G. under Grant No. DGE-1247312 and an NSF iDigBio grant to the NEVP.
- climate change
- fleshy fruit
- invasive species
- museum specimen
- temperate forest
- woody plants