Changing leaf colors in New England can be beautiful to behold at this time of year. But since it’s an annual biological event, the weather can have a big influence over when it happens, and just how colorful it can be.
A new study from UConn examines leaf color change and its timing. It shows that changing weather patterns -- and climate change in particular -- are having an impact on New England foliage.
According to the study, which focuses on New England deciduous forests, weather factors such as rainfall, drought, and heat stress from spring to fall can affect leaf color change and leaf drop -- also known as autumn phenology.
Yingying Xie, a UConn researcher, published the study on Monday in Proceedings of the National Academy of Sciences of the United States of America, shedding new light on this process. Xie is a PhD student in ecology and evolutionary biology.
What will foliage look like in New England in the coming years? Based on future climate projections over the next few decades, Xie and her colleagues predict that northern areas will have later color change and leaf drop, but the southern coastal areas will have earlier changes than current years.
Low temperatures and short day lengths are the most common factors triggering the color change, Xie said. This means that less brilliant colors are likely, since climate change increases night temperatures.
Xie also said that an earlier timeline for foliage color change is likely. Climate change -- including heavy rainfall -- means warmer autumns and more heat stress for trees. Those factors will probably trigger an earlier change overall for Connecticut's trees.
The most misunderstood thing about why leaves change color is the physiological and ecological mechanism behind it, she added. “The important job of plants in autumn before they shed leaves is recollecting nutrients, especially nitrogen from chlorophylls, in leaf cells,” said Xie.
Plants break down chlorophyll to transport nitrogen to other parts of plants, such as buds and trunks, Xie said. Nitrogen is limited in a natural environment, and it’s a key element for plants -- so they develop a way to save nitrogen every year.
What's actually happening when you see a leaf change from green to brilliant yellow? The colors represent the final developmental stage of plants in a growing season, Xie said. Technically, the chlorophyll in leaf cells is broken down, and there's no new supply. This means yellow pigments come through, and sometimes red pigments are made, too.
Enjoy the peak foliage while it lasts. In the near future, it may not be quite as colorful.
Stephanie Riefe is an intern at WNPR.