8/29/2023 0 Comments Autumn colors 2014To gain historical perspective on changes in fall foliage, Forkner and Alexis Garretson, now a doctoral student at the Jackson Laboratory in Maine, turned to herbaria-the plant collections maintained by universities and other institutions. One out of every five plant species documented in the park a century ago can no longer be found today. Trees and other plant life are feeling this change. In the past century, the park has warmed by 3.4☏. “This is the biggest signal we have seen,” says Stephanie Spera, an environmental scientist at the University of Richmond who is studying leaf changes in the park. In Maine’s Acadia National Park, scientists have noted a possible link between warm nights in September and delayed fall colors. We don’t have enough people researching it.” “If they’re not getting their nutrients back, we could see some problems in our forest, but it’s too early to know. “Plants have this amazing capacity to cope,” says Forkner, but scientists don’t yet know the limits of trees’ ability to adapt. Climate change is disrupting it in some species more than others, with unknown consequences. The process leading up to shedding is known as leaf senescence. Scientists think these red compounds are like a leaf’s winter coat, helping stave off the cold and allowing trees to absorb any last nutrients from the leaves before a cold snap kills the leaves. In addition, shorter, colder days prompt some tree species, including red and sugar maples, to produce red anthocyanins. All spring and summer, their leaves produce a green pigment called chlorophyll that captures sunlight, providing trees the energy to create the sugars and carbohydrates they need to grow and survive.Īs temperatures drop and days grow shorter, signaling an end to the growing season, trees respond by ending chlorophyll production and absorbing any remaining nutrients-in effect laying down stores for winter.īut lurking under that chlorophyll all spring and summer are orange and yellow-hued chemicals, which are unveiled as trees begin to go dormant. Like people, trees must prepare for the cold, dark winter. “While nobody wants to be the ‘sky is falling’ kind of person, we do understand these changes are the plants telling us something is not right.” “We ought to be concerned potentially, not just about timing of change for autumn, but whether or not it portends some forest collapse,” says George Mason University ecologist Rebecca Forkner. What that means for forests-how well trees grow, where they can live, and whether they can keep storing carbon at the same rate-is still unclear. What’s more, climate-related delays in leaf coloration are disrupting annual cycles of growth and rest that trees undergo. As climate change affects all those factors, it’s making the timing of peak foliage harder to predict. Temperature is not the only driver precipitation or the lack of it, extreme weather, and insect infestations also play a role. And the Northeast, which is most famous for fall foliages, is warming faster than the rest of North America.įrom Vermont to North Carolina, fall foliage has been appearing behind schedule-continuing a long-term trend that, according to one recent study of maples by researchers at George Mason University, has pushed the appearance of fall colors back more than a month since the 19th century. “You combine that with vivid fall colors and it’s just sort of magical.”īut fall is getting warmer as a result of climate change.įrom 2014 to 2021, the Northern Hemisphere experienced its eight warmest Octobers on record. “The mountains here in general are gorgeous,” says Larry Deane, a professional photographer who lives in the foothills of the Blue Ridge Mountains outside Asheville, North Carolina. The air is crisp, the days are still warm, and the turning foliage offers an irresistible riot of color-one that, by one rough estimate, generates as much as $30 billion a year in tourism revenue from Maine to the Carolinas. Fall is a special time of year in the forests along the eastern seaboard, as trees explode in brilliant shades of red and gold.
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