It’s all in the timing: Answering short term research questions while establishing a long-term phenology study

Background/Question/Methods

Phenology offers insights into species’ response to climate change. Shifts in phenology can disrupt ecological processes including: exposure to spring frost, availability of leaves for herbivorous insects, increase risk of seed predation, plant-pollinator interactions and seed production. Nantucket Island, Massachusetts is host to a unique assemblage of coastal shrubland, heathland, and the globally rare sandplain grassland. Species-specific responses to climate changes could result in alterations to these threatened habitats. In establishing a new, long-term phenological research program, we focus on common shrubs characteristic of the native plant communities. While we recognize the benefits of a long-term data-set, we begin by asking short-term research questions to 1) justify the expense and labor to our funding agencies, board of directors, and constituents, 2) offer educational opportunities to our community, and 3) provide a base for student research projects.  To accomplish this, we established eight plots across our study site with multiple individuals of each study species present and recording hourly temperature.

Initial questions: What are the main phenophases of the common, woody shrubs of the coastal heathland community? How do small differences in temperature (imposed by topography) affect the timing of these phenophases among plots and years? How do these differences vary among species?

Results/Conclusions

At the early stages of this phenology program, we have been able to identify the main phenophases of 10 of our common, native shrubs characteristic of the Nantucket coastal heathland communities. Among our plots, even slight variations in topography resulted in temperature differences of up to 10°C. These temperature differences had species-specific effects; some shrubs had more synchronous annual bud burst regardless of within-season temperature variation. Other species, such as Gaylusaccia baccata, had asynchronous bud burst spanning a 10 day period with leaf-out correlated with minimum spring temperatures. These results provide a base for a long-term research program. Additional years of data will help illustrate potential plant species’ responses to changing temperatures. Differential climate sensitivities have implications for the assemblages of shrub communities in these threatened systems with predicted warmer temperatures. If future communities leaf out and/or flower in novel assemblages, pollinator-mediated interactions may be altered and plant reproductive performance could be impacted.