Herbarium specimens show patterns of fruiting phenology in native and invasive plant species across New England

• Published in: American journal of botany Vol. 105; no. 1; pp. 31 - 41
• Main Authors: Gallinat, Amanda S., Russo, Luca, Melaas, Eli K., Willis, Charles G., Primack, Richard B.
• Format: Journal Article
• Language: English
• Published: United States John Wiley and Sons, Inc 01-01-2018; Botanical Society of America, Inc
• Subjects: Animal nutrition; Animal Nutritional Physiological Phenomena; Animals; Birds; Birds - physiology; climate change; Dispersal; Dispersion; Feeding Behavior; fleshy fruit; Fruit - growth & development; Fruits; Indigenous species; Introduced Species; Invasive plants; Invasive species; Magnoliopsida - growth & development; Migratory birds; museum specimen; New England; Nonnative species; Nutrition; Phenology; Phylogenetics; Phylogeny; Plant species introduction; RESEARCH ARTICLE; ripening; Seasons; Seed Dispersal; Seeds; Species Specificity; temperate forest; Temperature; Temporal resolution; woody plants; New England; New England states; temperate forest; museum specimen; ripening; woody plants; fleshy fruit; invasive species; climate change
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/ajb2.1005

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.