News
Trees ‘remember’ wetter times − never having known abundant rain could buffer today’s young forests against climate change
In a changing climate, trees exhibit “legacy effects” from past droughts or wet periods. Young trees, adapted to arid conditions, offer hope for future forest resilience amidst escalating climate challenges globally.
Alana Chin, Cal Poly Humboldt ; Janneke Hille Ris Lambers, Swiss Federal Institute of Technology Zurich, and Marcus Schaub, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
What does the future hold for forests in a warmer, drier world? Over the past 25 years, trees have been dying due to effects of climate change around the world. In Africa, Asia, North America, South America and Europe, drought stress amplified by heat is killing trees that have survived for centuries.
Old trees may have grown through entire millennia that were wetter than the past 20 years. We are scientists who study forest dynamics, plant ecology and plant physiology. In a recent study, we found that trees can remember times when water was plentiful and that this memory continues to shape their growth for many years after wet phases end.
This research makes us optimistic that young trees of today, which have never known 20th-century rainfall, have not shaped their structure around water abundance and thus may be better equipped to survive in a chronically dry world.
What if we water the forest?
This study built on nearly 20 years of forest research in response to early warning signs of forest loss in the 1990s in the dry Rhône River Valley of the Swiss Alps. At that time, scientists observed that Scots pine trees that had stood for around 100 years were declining and dying. They wondered whether drought or other climate factors were driving this loss.
To tackle this question, researchers at the Swiss Federal Institute for Forest, Snow and Landscape Research designed an ecological experiment. To understand the impacts of drought, they would irrigate a mature forest, doubling natural summertime rainfall, and then compare how these water-rich trees fared in comparison with those receiving only natural precipitation.
The Pfynwald experiment, launched in 2003, has shown that trees survived at higher rates in irrigated plots. After 17 years of irrigation, the team found that irrigation didn’t just help trees survive dry phases – it also increased their growth rates. https://www.youtube.com/embed/OA7A-xWhDeo?wmode=transparent&start=0 Tree physiologist Leonie Schönbeck conducts research at Pfynwald, a natural reserve in southern Switzerland, to learn how trees take up and store energy and use their reserves to recover from drought.
Legacy effects are forests’ memories
Trees experiencing drought alter their leaves, wood and roots in ways that prime them for continued dry conditions. Wood under drought might have smaller cells that are less vulnerable to future damage, and roots might increase relative to leaf area. These structural changes persist after the drought has passed and continue to influence the tree’s growth and ability to tolerate stress for many years.
Known as “legacy effects,” these lingering post-drought impacts represent an ecological memory of past climatic conditions at the tree and forest level. Knowing that trees hold a persistent memory of past dry phases, researchers wondered whether they might also show structural changes in response to past wet periods.
Eleven years after summertime irrigation started in Pfynwald, scientists stopped irrigating half of each plot in 2013 to address this question. The formerly irrigated trees, which at this point were about 120 years old, had experienced a lasting period of irrigation – but now those times of plenty were over.
Would the trees remember? A decade later, we found out.
Trees, trains and particle accelerators
On an early March morning in 2023, two of us (Alana Chin and Marcus Schaub) met at Pfynwald to collect very fresh leaf and twig samples so that we and colleagues could look inside to search for signs of lasting effects of past water richness.
At the site, we climbed canopy access towers to collect newly grown treetop leaves and twigs from control trees that had never been irrigated; trees that had been irrigated every summer since 2003; and formerly irrigated trees that had not received irrigation water since 2013.
We took our samples to the Swiss Light Source, an intensely powerful synchrotron – a type of particle accelerator that produces the world’s most intense beams of light. This facility is the home of the TOMCAT, an extremely high-resolution X-ray that allowed us to look inside our leaves and twigs without disturbing their structure.
Scanning our samples took all night, but when we stumbled out of the building, we had images capturing every cell in exquisite detail.
The memory of water
We found that the new leaves of once-irrigated trees were different from both continually watered trees and never-watered control trees. Leaves carry out photosynthesis that fuels a tree’s survival and growth. Inside them, we could see the legacy of past water abundance, written in the size, shape and arrangement of cells.
Reading this cellular signature, we observed that, at the expense of structures promoting productivity, formerly irrigated trees showed every sign of chronic water stress – even more so than never-irrigated trees. In their anatomy, we saw why these trees that had it easy for 11 wet years were now growing slowly.
Every cell in a leaf comes with a trade-off. Trees must balance investments in rapid photosynthesis with others that promote leaf survival. Rather than building the cells used to harvest sunlight and ship sugar to the rest of the tree, leaves on the trees that had been irrigated showed every indication of drought stress we could think to measure.
After receiving extra water for an 11-year stretch and then losing it, the trees were producing new, tiny leaves that invested mostly in their own survival. The leaves were structured to protect themselves from insects and drought and to store water reserves. Compared with leaves on trees that had never known irrigation, these looked as though they were in the middle of the drought of the century.
While this memory of water might seem negative, it likely once helped trees “learn” from past conditions to survive in variable environments. The formerly irrigated trees did not know that humans had played a trick on them. Like trees experiencing climate change, they had no way of knowing that the water was not coming back.
When trees experience a drought event, recovery can mean reaching a “new normal” state, in which they are prepared to survive the next drought, with smaller, less vulnerable cells and increased energy reserves to ‘save up’ for future dry periods. They may have deeper roots or a smaller pool of leaves to support, helping them prepare for an unstable environment.
We wanted to know whether the same was true of trees that had experienced water abundance. Were they waiting in distress for the water to return?
Hard times may make tough trees
In some temperate forests, like the ones we studied in Switzerland, old trees once knew levels of water abundance that now are gone, thanks to climate change. That past abundance may have locked into place structural and epigenetic changes in the trees that are mismatched to today’s drier world. If this is true, then some of today’s devastating global tree mortality events may be, in part, due to the legacy effects of past water abundance.
In most of the world’s temperate forests, however, the current cohort of young forest trees – those sprouting in the past 15 to 20 years – has managed to establish itself under conditions that once would have been considered chronic drought. Those young trees, which have survived an endless dry period, will form the forests of the future.
In all, our observations in Pfynwald have provided us some room for hope that young trees currently taking their place in many forests worldwide may be better prepared to cope with the world as humans have shaped it. Climate shifts in recent decades have primed them for hard times, without the lingering memory of water.
Alana Chin, Assistant Professor of Plant Physiology, Cal Poly Humboldt ; Janneke Hille Ris Lambers, Professor of Environmental Systems Science, Swiss Federal Institute of Technology Zurich, and Marcus Schaub, Group Leader, Forest Dynamics and Ecophysiology, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Food Truths
The Truth About the “Chemical” in McDonald’s Burger Buns: Should Consumers Be Concerned?
What’s in the Burger Buns:The “yoga mat chemical” controversy changed how consumers view food additives. Here’s what azodicarbonamide is, why McDonald’s removed it, and what the science actually says.
For years, headlines and social media posts have warned consumers about a so-called “yoga mat chemical” found in hamburger buns served by major fast-food chains. The claims sparked widespread concern, prompted petitions, and eventually led several restaurant companies—including McDonald’s—to change their recipes.
But what was the chemical, and is there actually a health risk today?
What Was the Controversial Ingredient?
The ingredient at the center of the controversy was azodicarbonamide (ADA), a chemical used as a dough conditioner. It helped improve the texture of bread, making dough easier to handle and producing softer, more consistent buns.
Ironically, the same compound is also used in manufacturing certain foamed plastics, including some yoga mats and shoe soles. That connection gave rise to the viral nickname, “the yoga mat chemical.”
While the comparison was technically accurate, it also lacked important context. Food-grade azodicarbonamide and industrial applications are very different, and many chemicals have multiple uses across industries.
Why Did People Become Concerned?
The concern wasn’t simply that ADA was used in food. Scientists focused on what happens during baking.
When bread is baked, most azodicarbonamide breaks down into other compounds. Some laboratory studies involving animals raised questions about one of these breakdown products, called semicarbazide (SEM), when administered in high doses.
Those findings prompted some countries to take a more cautious regulatory approach.
Why Is It Banned in Some Countries?
The European Union and Canada do not permit azodicarbonamide as a flour treatment agent. Their food safety policies often follow the precautionary principle, removing ingredients when safer alternatives exist or when scientific uncertainty remains.
In contrast, the U.S. Food and Drug Administration has determined that azodicarbonamide is safe when used within approved limits.
These differing regulations don’t necessarily mean one side believes the ingredient is dangerous while the other believes it is harmless. Instead, they reflect different philosophies about regulating food additives.
Does McDonald’s Still Use It?
No.
McDonald’s removed azodicarbonamide from its U.S. hamburger buns in 2014 following growing consumer demand for simpler ingredient lists.
Today’s buns no longer contain the ingredient, joining a broader trend among food manufacturers to eliminate additives that have become controversial with consumers.
Are There Other Ingredients Consumers Should Know About?
Modern commercial bread still contains ingredients designed to improve freshness, texture, and shelf life.
These may include:
- Calcium propionate to prevent mold
- Ascorbic acid (Vitamin C) as a dough conditioner
- Enzymes that improve consistency
- Emulsifiers that help maintain softness
These ingredients have been evaluated by food safety agencies and are generally recognized as safe when used according to regulations.
The Bigger Health Picture
Nutrition experts generally agree that focusing on one ingredient can distract from the larger issue.
The greatest health risks associated with fast food are more closely linked to:
- High sodium intake
- Excess saturated fat
- Added sugars
- Large portion sizes
- Frequent consumption of ultra-processed foods
An occasional fast-food meal is unlikely to determine someone’s long-term health. Overall dietary patterns, physical activity, sleep, and other lifestyle factors have a much greater impact.
Consumer Awareness Is Changing the Food Industry
Whether or not an ingredient poses a measurable health risk, public concern can influence corporate decisions.
Over the past decade, many food companies have reformulated products to remove controversial ingredients, reduce artificial additives, and simplify ingredient labels. In many cases, those changes have been driven as much by consumer preferences as by regulatory requirements.
The Bottom Line
The “yoga mat chemical” story captured public attention because it combined science, food safety, and memorable marketing. While azodicarbonamide was once used in some hamburger buns, including those supplied to McDonald’s, the company removed it from its U.S. buns years ago.
Current evidence suggests consumers are better served by paying attention to their overall diet rather than worrying about a single ingredient that has already disappeared from many products.
Being an informed consumer means looking beyond the headlines, understanding the science, and recognizing that nutrition is about the complete picture—not just one ingredient.
Related External Links
- U.S. FDA – Food Additives & GRAS Ingredients Information for Consumers
- U.S. FDA – Food Additives and Petitions
- FDA – Azodicarbonamide (ADA) Food Substance Database
- Electronic Code of Federal Regulations – 21 CFR §172.806 (Azodicarbonamide)
- FDA – Types of Food Ingredients and Why They’re Used
- Health Canada – Permitted Flour Treatment Agents
- McDonald’s USA – Nutrition Calculator & Ingredient Information
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STM Blog
Association of Black Cardiologists to Celebrate Legacy and Leadership at 16th Annual Spirit of the Heart Awards
The Association of Black Cardiologists (ABC) is bringing its signature celebration of impact back to New York City this fall—spotlighting leaders and organizations working to make cardiovascular care more equitable, more accessible, and more effective. The 16th Annual Spirit of the Heart Awards Program & Fundraiser is set for Saturday, October 3, 2026 (6:00 p.m.–9:00 p.m.) at Cipriani Wall Street in Manhattan.
For ABC, the evening is more than a high-profile awards program. It’s a cornerstone fundraising event that helps power the organization’s year-round work—supporting medical student scholarships, fellowships, education, and programs designed to strengthen the pipeline of diverse clinicians and researchers while improving outcomes in communities that carry a disproportionate burden of heart disease.
A fundraising night with long-term stakes
ABC leaders say the Spirit of the Heart Awards is built around a simple idea: celebrating progress while investing in the people who will drive the next wave of change.
Event co-chair Icilma Fergus, MD—Director of the Cardiovascular Disparities Center at Mount Sinai Medical Center and Board Chair of ABC—framed the night as a forward-looking commitment.
“This gathering is about more than one evening of celebration; it is about investing in the future of cardiovascular health for years to come,” Fergus said in the announcement. She added that the support generated through the event helps expand opportunities for aspiring clinicians, researchers, and leaders whose work can transform care and improve lives nationwide.
Honorary Chairperson: Samin K. Sharma, MD
ABC announced Samin K. Sharma, MD as the event’s Honorary Chairperson. Sharma serves as Chief of Clinical Cardiology, Director of the Cardiovascular Clinical Institute, and the Anandi Lal Sharma Professor of Medicine at the Icahn School of Medicine at Mount Sinai.
In the release, ABC highlighted Sharma’s international reputation in interventional cardiology and physician education, noting that he has trained cardiovascular specialists from around the world while advancing the field through research, mentorship, and patient care.
“I am honored to serve as Honorary Chairperson for this important event,” Sharma said. “The Spirit of the Heart Awards Program reflects the power of partnership, philanthropy, and leadership to advance cardiovascular health.”
A full weekend of impact, including policy
The awards program is part of a broader weekend of programming. On Friday, October 2, ABC will host its Annual Policy Pulse Summit at Venable LLP in New York City, convening leaders to discuss policy issues shaping the future of cardiovascular health.
What to expect at the Spirit of the Heart Awards
ABC is positioning the evening as both a celebration and a community gathering—bringing together leaders from healthcare, philanthropy, industry, and advocacy.
The event will be co-emceed by:
- Sandra Bookman, award-winning journalist and anchor of Eyewitness News on ABC7/WABC-TV New York
- Thomas Cunningham IV, President and Chief Content Officer of BrandCunningham
The program is expected to include:
- Presentation of the Spirit of the Heart Awards
- Recognition of medical student scholarship recipients
- Special guest appearances
- A live auction
- Musical entertainment
Event co-chair Barbara Hutchinson, MD, PhD, President of Chesapeake Cardiac Care, emphasized the role of sustained collaboration in moving the needle on heart health.
“The Spirit of the Heart Awards Program is a reminder that lasting progress in cardiovascular health is achieved through vision, partnership, and sustained commitment,” Hutchinson said.
How to attend, sponsor, or support
ABC is directing attendees and supporters to its event site for tickets, sponsorship opportunities, and donations:
- Event info / tickets / sponsorship / donations: https://abcardioevents.org
About the Association of Black Cardiologists
Founded on the belief that “every heart counts,” the Association of Black Cardiologists works to promote prevention and treatment of cardiovascular disease and to advance health equity by eliminating disparities. ABC’s membership is open to all, regardless of race, ethnicity, or vocation. The organization’s work spans education, advocacy, research, patient and community outreach, and leadership development.
- Organization website: https://abcardio.org
Source and media contact
- Press release source (PRNewswire): https://www.prnewswire.com/news-releases/association-of-black-cardiologists-to-celebrate-legacy-and-leadership-at-16th-annual-spirit-of-the-heart-awards-302206000.html
Media Contact (from the release):
- Akeia Blue, VP of Communications
- 419395@email4pr.com
- 240-321-9227
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Food and Beverage
Millions of Eggs Recalled Over Possible Salmonella Risk: What Consumers Need to Know
A major egg recall is affecting nearly 1.6 million dozen eggs sold under several popular brands. Here’s how to determine if your eggs are included and what steps to take if they are.
News You Can Use This Moment!
Consumers are being urged to check their refrigerators after a major recall involving nearly 1.6 million dozen shell eggs due to the potential presence of Salmonella Enteritidis, a bacterium that can cause serious foodborne illness.
The voluntary recall, announced by Midwest Poultry Services, L.P., affects white shell eggs and brown cage-free eggs produced at two Texas farms and distributed between June 6 and July 3, 2026. According to the U.S. Food and Drug Administration (FDA), the eggs were sold through grocery stores and foodservice distributors in Texas, Louisiana, Oklahoma, Arkansas, Mississippi, and New Mexico.
What Brands Are Included?
The recalled eggs were sold under several familiar brand names, including:
- Kroger
- Simple Truth
- Brookshire’s
- Country Morning
- Sunups
Not every carton under these brands is affected. Consumers should look for:
- Plant Code: P-1950 or 0840962
- Julian Dates: 157 through 184
- Best By/Sell By Dates: July 20, 2026, through August 17, 2026
Why the Recall Matters
Salmonella can cause symptoms including:
- Diarrhea
- Fever
- Stomach cramps
- Nausea
- Vomiting
Symptoms typically begin 12 to 72 hours after eating contaminated food and usually last four to seven days. While many healthy adults recover without treatment, infections can become severe in young children, older adults, pregnant women, and people with weakened immune systems.
The FDA and the Centers for Disease Control and Prevention (CDC) are investigating a multistate outbreak involving 98 confirmed illnesses across 17 states, resulting in 26 hospitalizations. No deaths have been reported. Investigators say the recalled eggs are linked to part of the outbreak, although they do not account for every reported illness.
What Should You Do?
If you have eggs matching the recalled codes:
- Do not eat them.
- Return them to the store for a refund or dispose of them safely.
- Wash your hands thoroughly after handling the carton.
- Clean and sanitize any refrigerator shelves, containers, or kitchen surfaces the eggs may have touched.
If you have already eaten the eggs and develop symptoms of Salmonella infection, contact your healthcare provider, especially if symptoms are severe or persist.
Are Arizona Consumers Affected?
The recalled products were officially distributed in six states, and Arizona is not listed among the primary distribution states. However, because food products can move through wholesalers, travelers, or secondary retailers, Arizona consumers who recently purchased eggs while traveling—or who received eggs from family or friends in affected states—should still check the carton codes.
The Bottom Line
Food recalls are an important part of protecting public health. Taking a few moments to inspect the eggs in your refrigerator could help prevent a serious illness. If your carton matches the recalled plant codes and date range, don’t take the risk—return it or throw it away.
STM Daily News will continue to monitor this developing story and provide updates as additional information becomes available.
Related Resources
- FDA Recalls, Market Withdrawals & Safety Alerts
- FDA Foodborne Illness Outbreak Investigations
- CDC: Salmonella Information
- FoodSafety.gov Consumer Resources
