Abstract Detail

Ecological Section

O'Leary-Ponzo, David [1], Filó, Luiz E. C. [2], Metsger, Deborah A. [3], Dickinson, Tim [1].

Ontario spring-flowering species and climate change.

Because phenology may be dependent on external cues, it is expected that organisms may respond to a warming climate by changing the timing of their phenophases. Recently, herbaria have been recognized as sources of historical phenological data through which problems such as plant responses to climate change can be examined. The use of data from herbarium specimens makes possible the study of large sample sizes over more than a century. At the same time, however, dealing with collections made in regions where climate may vary dramatically with geography poses challenges for the use of these data. We have collected data from Ontario specimens of Maianthemum canadense, Claytonia virginica, and Crataegus punctata in the Green Plant Herbarium of the Royal Ontario Museum, as well as from specimens in the Herbarium of the Canadian Museum of Nature. We selected specimens in which individuals have some but not all of the flowers on their inflorescence fully opened. We then recorded the Julian date at which this stage was reached, together with the year of collection and the geographic coordinates of the collection site. Our data extend back over the past 100-150 years.

The province of Ontario extends over 15 degrees of latitude, and lies on the shores of four of the Great Lakes. Although altitudinal variation is limited, what relief there is interacts with these other factors to produce a highly non-linear advance of spring. We used maps depicting the seasonality of the Ontario climate in order to control for this non-linearity in analysing the relationship between year of flowering and the Julian date of flowering. With this control, both the Maianthemum data and the Crataegus data showed signs that vernal accumulated heat may function as a proximal cue for flowering. Accumulated heat values for the onset of flowering in the species we examined have largely remained constant over the past century. At the same time, recent flowering dates are earlier than was the case 50-100 years ago. In contrast, the Claytonia data show a much more ambiguous pattern. We speculate about the possible role of growth form in the similarities and differences we have observed.

1 - University of Toronto, Ecology and Evolutionary Biology
2 - University of São Paulo
3 - Royal Ontario Museum, Natural History

Keywords:
phenology
Ontario
herbarium
climate change
Maianthemum canadense
Crataegus punctata
Claytonia virginica.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PEC035
Abstract ID:975
Candidate for Awards:Ian and Syvia Taylor Award