Before winter ends, trees begin to bud, and sap starts flowing again… This poses a risky strategy for plants. “ This is the result of a long evolutionary history ,” explains botanist Yves Caraglio.
This article is published in partnership with a magazine.
Why the 12-5-30 Incline Walking Method Is the Ultimate Fat-Burning Workout, According to Fitness Experts
The ultimate trick to banish mold from your bathroom grout in just 7 minutes—no vinegar or baking soda needed
In March, buds are already evident on some trees despite the risks of frost. Yves Caraglio, a botanist at the mixed research unit for botanical and bioinformatics of plant architecture (Amap) in Montpellier, discusses the reasons behind early budding.
The Salamander — Why do some trees bud before winter ends ?
Yves Caraglio — It partly stems from the long evolutionary history of different species and their biogeographic origins, each finding their niche in various ecosystems and within the seasonal calendar. Capitalizing early on the increasing light before the foliage becomes widespread can be an advantage. Or, for instance, aligning their awakening with the emergence of a specific pollinator.
However, there are risks involved. When budding occurs, leaf spread begins and sap circulation resumes. Since buds protect leaf primordia from the cold, if winter has not yet fully passed, the floral parts and young shoots can freeze.
How does the plant respond to this risk ?
The plant must mobilize stem cells from the meristem to replace the parts affected by the cold. If these disturbances recur, they will lead to energy consumption that can deplete the specimen.
In some regions, species like oaks naturally produce several shoots in a season. Thus, they are less penalized by temperature fluctuations. However, they suffer more from water shortages and droughts. The effects of climate change also impact fruit production since early budding remains vulnerable to frost until May.
How does the plant adapt to these variations ?
In a population, there is variability that helps to mitigate these effects. Individuals that better resist disturbances are naturally selected. But trees have a life cycle and a time span between generations that are longer than those of, say, a fly, so this genetic selection takes time. However, freezes aren’t guaranteed every year, and the early bloomers reproduce and thus survive within the population.
When are buds formed ?
Most plants pre-manufacture them at the end of summer when photosynthesis provides a significant energy source. At the very beginning of the following spring, initiating leaf growth and spreading them will require a lot of energy and water conduction from internal sources. Anticipated production thus allows plants to conserve their resources during this crucial season. Nevertheless, during winter, even though it is dormant, the bud slowly matures and grows, as cellular divisions still occur quietly.
| This article is from issue No. 286 of the Salamandre Review. |
