How Redlining Shaped Baltimore’s Tree Canopy Redlining was pervasive in American cities from the 1930s through the late 1960s. Maps were drawn specifically to ensure that Black people were denied mortgages. These discriminatory practices created a lasting legacy of economic and racial inequality which persists today. Less obvious is how redlining has shaped nature and the urban ecosystem. A recent study found that previously redlined neighborhoods in Baltimore have fewer big old trees and lower tree diversity than other parts of the city. These findings are part of the Baltimore Ecosystem Study, a collaborative research project which has tracked the city’s changing urban environment for the past 25 years. But it’s not all bad news. The city has a comprehensive tree replanting initiative and is now working to restore its tree canopy. In 2007, Baltimore set a goal to increase the tree cover from 20% to 40% by 2037. Since then, officials have been working closely with non-profit community organizations to plant trees all over the city—especially in previously redlined and otherwise under-served neighborhoods. Ira talks with Karin Burghardt, assistant professor of entomology at the University of Maryland about her latest research into the effect of redlining on Baltimore’s tree ecosystem. And later, Ira speaks with Ryan Alston, communications and outreach manager for Baltimore Tree Trust, which has planted over 16,000 trees in the city to date.   What’s Going On Underground With Gophers? Pocket gophers, also known as gophers, are often viewed as a pest species. But their extensive tunnel networks are good for soil and help shape healthy ecosystems everywhere gophers are found. Producer Christie Taylor talks to two University of Florida researchers who investigated the mystery of the pocket gopher—why does a single gopher build such a large network of tunnels? What they found led to deeper questions about how gophers get enough food for their extensive energy needs, and whether they might even be cultivating roots in a deliberate act of farming. Plus, why pocket gophers deserve our appreciation as ecosystem engineers.   How This Chemist Is Turning Agricultural Waste Into Water Filters Activated carbon filters have become common household items as water filters in pitchers, or directly on your faucet. These activated carbon filters are also used in industrial processes like wastewater treatment and to filter out chemicals released in smokestacks. Dr. Kandis Leslie Abdul-Aziz, assistant professor of chemical and environmental engineering at University of California Riverside, has created activated carbon filters from agricultural waste like corn stover and orange peels. Abdul-Aziz talks with Ira about her research, and what it will take to shift manufacturing processes to be more sustainable and less harmful to the planet.     The Nose Knows When It’s Cold—And It May Get You Sick It’s something most of us know from experience: When it’s cold outside, you’re likely to see a lot of people sneezing and coughing. Upper respiratory infections, like the flu, colds or even COVID-19 are common in winter. But understanding the biological reasons why hasn’t been known—until now. Researchers at Mass Eye and Ear cracked the mystery in the Journal of Allergy and Clinical Immunology last month. The study points to the cold-sensitive nose—specifically extracellular vesicles inside nose cells—as the key immune response impacted by temperature. It turns out that a temperature drop of about 40 degrees Farenheit triggers a severe decrease in the quantity and effectiveness in EVs, decreasing the body’s ability to prevent infection. Ira speaks to the study’s lead author Benjamin Bleier, associate professor at Mass Eye and Ear in Boston, Massachusetts, about this breakthrough and the impact it could have on future treatments for respiratory illness.   By Hiding Their Blood, These Frogs Pull Off The Ultimate Disappearing Act Glass frogs have a superpower: If you look at them from above, they look like regular green frogs. But if you flip one over, you can see right into their bodies: hearts, intestines, bones, and all. As these frogs doze off, however, something changes: They disappear. Well, almost. A new study shows that the frogs can hide their red blood cells as they sleep, becoming expert camouflagers. Dr. Carlos Taboada, a biologist at Duke University, is a co-author on this study and he joins Ira to talk about the glass frogs’ tricks.   Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.