Leaves Changing

Behind the scenes: vibrant foliage

The science of leaves changing colors in fall

Veda Thangudu thangved000@hsestudents.org

It is the time of the year when the weather starts to cool down and leaves start to fall o trees. Fall is mainly characterized by the color change in leaves. Biology teacher Alex Smith talks about the science behind leaves changing color. “Plants have chemical mechanisms that let them tell how much daylight there is in the day,” Smith said. “Because [plants] know the days are getting shorter and they have less daylight to make carbohydrates, they’re going to start slowing down production of things like chlorophyll, which they use to harness the sun’s energy.” Chlorophyll is green in color. Additionally, plants have other pigments in the background like carotenoids, which are di erent colors. “Chlorophyll breaks down, the green color goes away, and then all that’s le are the carotenoids, which are red-brown, the fall colors,” Smith said. While it may seem visually appealing to humans, leaves changing colors and falling o from trees has other e ects on the ecosystem. Along with signifying the end of growth season for plants, there are negative impacts on the environment. “Leaves are a really important food source for a lot of organisms,” Smith said. “During the fall, leaves become less nutritious and start to drop o plants.” Once they fall o plants and hit the ground, decomposers start breaking them down, leaving numerous species of birds and herbivores food-less. “ at’s why they’ve developed strategies to deal with winter,” Smith said. “Lots of mammals hibernate during the winter because there’s less food. Birds will migrate to nd more plentiful food sources near the equator. Camou age is set up for spring and summer, so prey might be more vulnerable during fall and winter.” e science behind leaves changing colors during this season can induce certain emotions from people whether that be positive or negative. Junior

Zeina Wanas thinks that the weather helps support many activities like biking and walking. “I think that fall is the best season of the entire year,” Wanas said. “De nitely because of the weather and the way it looks - the orange and red leaves - everything about it is so pretty and the weather is not too cold, not too warm.” Another element that Wanas likes about fall is the fall avors at multiple restaurants. Cafes and restaurants re-introduce their fall collection, bringing back their pumpkin spice and cinnamon themed foods and drinks. “Pumpkin spice lattes are so good,” Wanas said. “Anything pumpkin spiced or cinnamon, [or] anything fall avored is just so good.” Although Wanas has her reasons to like fall, sophomore

Krishna Patel thinks it is over hyped. She believes that the weather gets too cold. “It’s a hassle readjusting to the whole school schedule, and waking up early during cold days [is hard],” Patel said. Patel brings up the point of how spring is known to be ‘allergy season’ and fall is o en not considered as a time for allergies to kick in. According to the American College of Allergy, Asthma and Immunology (ACAAI), ragweed is the most common trigger for fall allergies. “You can also have allergies during fall,” Patel said. “ ey might not be as strong, but you can still have them during fall.” Similar to how the environment a ects humans, the reverse occurs as well. Smith believes that foliage can be impacted by a variety of human activities, like migration and shipping. One instance of that can be found locally. According to Indiana’s Department of Natural Resources, a pest named Hemlock Woolly Adelgid(HWA) was identi ed in LaPorte county in the mid 1920s, and eventually spread all across southern Indiana. It is an invasive species that transfers by attaching to items. HWA fed on deciduous trees, negatively impacting the native plants. “A lot of the colors that used to be present in these beautiful forest landscapes are starting to become rarer, as the pest destroys native plants,” Smith said. Furthermore, Smith mentioned how humans can contribute to the environment through a very simple task at this time of the year. According to him, it is okay to pick up fallen leaves o private yards, but not in a wooded area. In those locations, leaves should be le on the ground. “Big trees drop their leaves and it serves as a mechanism for killing o other competitive plants,” Smith said. “So if you pick up leaves, it makes it more likely for invasive plants to come in and harm native ora.”