Science Seminar Series Resumes

January 11, 2011

BRANDON, MB — The Science Seminar Series begins its winter semester offerings on Friday, January 14, with Dr. Terrence McGonigle, the chair of the Department of Biology. His talk, entitled “Degree-day prediction of first flowering in subarctic Manitoba” will take place at 3 p.m., in Room 342 in the Brodie (Science) Building. Admission is free.

The Abstract for this talk is as follows:

“The date of first flowering was recorded from 2001 to 2009 for seven subarctic angiosperm species around Churchill. At the same sites, mean daily temperatures were determined for monitoring on 5-minute intervals at heights relative to the soil surface of 150 cm, 0 cm, -5 cm and -10 cm. Degree days for first-flowering were calculated using threshold temperatures of 2oC, 0oC, and -5oC. Using coefficient of variation (cv) for means across years, degree-day scores (DS) were considered less variable than numeric scores for calendar dates (NS) when cvDS/cvNS was <0.9 for a combination of species and site.

Irrespective of threshold, degree-days offered considerable advantage over calendar date to predict flowering when temperature was recorded at 150 cm height for Dryas integrifolia, Ledum palustre ssp. decumbens, Ledum groenlandicum, and Vaccinium vitis-idaea. For these species, other heights for temperature monitoring were less reliable predictors of flowering. In contrast, either 150 cm or 0 cm above soil surface was equally effective for Saxifraga oppositifolia, but a threshold of -5oC was essential to predict flowering for this species.

Degree-days offered no advantage over calendar date to predict flowering for Arctostaphylos rubra and Salix reticulata. Degree-day values were site-specific, where multiple sites were investigated, indicating that environmental factors in addition to day-length and temperature contribute to flower initiation for L. palustre ssp. decumbens, L. groenlandicum, and Vaccinium vitis-idaea. The utility of degree-days to predict flowering suggests that temporal patterns of flowering will be modified across the subarctic as climate warming proceeds.”

The next seminar is slated for January 21, when Louise Buck will discuss “HGIS and 19th-century St. Mary’s River Maps.”

For more information, contact:

Joanne F. Villeneuve
Brandon University
270 – 18th Street
Brandon, MB R7A 6A9
Tel. 204-727-9762