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Bullard Spotlight: Isabelle Chuine on What Makes Spring Buds Burst

Tuesday, May 1, 2018
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Several times a year, we feature research by one of Harvard Forest's Charles Bullard Fellows. This spring, we're highlighting Isabelle Chuine, a research director at CNRS (French National Center for Scientific Research), based at the Centre of Functional and Evolutionary Ecology in Montpellier.

Her research lies at the interface of functional ecology and evolutionary ecology. She focuses on the ecological niches and phenology of forest trees, using a combination of modelling, experimental work in both field and controlled conditions, and long-term monitoring of natural populations. Her work is grounded in climate change investigation: the models she develops are intended to provide accurate forecasts of species distribution and phenology for the coming centuries. She has created a national observatory on phenology and a citizen science program called the Observatoire Des Saisons

During her 2017-2018 Bullard Fellowship, Chuine has been based primarily at Harvard's Arnold Arboretum in Boston, working in collaboration with Elizabeth Wolkovich. Chuine has been conducting experiments to investigate the factors that determine bud dormancy in trees growing at Harvard Forest (red oak, yellow birch, sugar maple, beech) - trees for which phenology has been monitored for more than 25 years by John O'Keefe

Her research question is timely in the context of global climate change. Models project a phenomenon called "dormancy break failure" - or, a failure to meet the winter cold duration needed by trees to produce growth hormones for leaf-out in spring - at tree species' warmer range margins by the end of the 21st century.

For Chuine, the most rewarding aspects of the Bullard Fellowship have been "the amazing facilities available," especially the growth chambers and the microscopy lab at the Arnold Areboretum, and "interesting and inspiring discussions with people at Harvard Forest and at the Arboretum." Equipment at the Arboretum has allowed her to monitor buds' dormancy state using aniline blue staining of callose (see photo), a plant polysaccharide that may be a plant's key to managing dormancy. She says her Fellowship work in the lab has been very intensive, but very exciting and fruitful.

(Photo: bud section under epifluorescence microscope with aniline blue staining of callose in the bud phloem, courtesy of Isabelle Chuine)

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