megafires

Megafires and orchard health

November 1, 2024 By EarthWise Leave a Comment

The frequent and massive megafires in places like Canada and the American west have led to a lot of research on the impact of smoke on humans but there has been less study of the effects of smoke on plant health. Researchers at the University of California, Davis have found that trees are just as vulnerable as humans are to the harmful effects of long-term exposure to smoke.

The Davis researchers studied almond, pistachio, and walnut trees at 467 orchard sites in California’s Central Valley from 2018 to 2022. In 2022, so-called megafires burned more than 4.2 million acres in California, pouring ash and smoke into the sky. The researchers had been studying how trees store carbohydrates to cope with heat and drought.

With the onset of the fires, they saw an opportunity to study how smoke affects carbohydrate levels. Trees use stored carbohydrates to sustain them through winter dormancy and spring growth. Trees produce carbohydrates via photosynthesis and thick smoke blocks the amount of light reaching the trees. Beyond that, there are other aspects of wildfire smoke, such as particulate matter and ozone that appear to affect photosynthesis.

The team found that the smoke not only reduced the amount of carbohydrates in trees but also caused losses that continued even after the fires were extinguished. This led to nut yield decreases of 15% up to 50% in some orchards. The researchers expected to see some impact on the trees during periods when smoke was really dense but were not expecting the smoke to have such a lingering effect and result in a significant drop in yield.

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Smoke From Megafires Puts Orchard Trees at Risk

Photo, posted October 1, 2008, courtesy of Suzi Rosenberg via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Megafires and ecosystems

November 15, 2023 By EarthWise Leave a Comment

Wildfires are a natural phenomenon. They have occurred long before there were people around. Ecosystems adapt to fires and some species can benefit from them or even depend upon them. But in recent times, fires have been intensifying and increasing in frequency and they are beginning to outstrip nature’s ability to bounce back from them.

So-called megafires – ones that dwarf typical wildfires in size – have an immediate ecological toll. They kill individual plants and animals that might have survived smaller fires.

Over millennia, many species of plants and animals have evolved to adapt to periodic fires. They are especially sensitive to smoke and take protective action in a timely fashion. Others take advantage of food sources that arise when trees burn.

But even species that capitalize on burned-out areas of forests require oases of healthy woodland for at least part of their activities. When fires are too widespread, such oases are too few and far between.

Animals that survive fires must find food, water, and shelter in the aftermath. And all air-breathing animals are going to be impacted by smoke exposure because the chemicals in smoke are toxic to them as well as to people.

In places like Canada’s Northwest Territories, repeated fires have transformed some forests, eliminating dominant tree species and replacing them with others whose light seeds were carried on the wind.

Scientists have estimated that increased global fire activity could push more than 1,000 threatened plant and animal species closer to extinction. Changing fire patterns are transforming landscapes and utterly remaking ecosystems.

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How Megafires Are Remaking the World

Photo, posted December 19, 2022, courtesy of Brian Pippin/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fighting Zombie Fires | Earth Wise

April 30, 2021 By EarthWise Leave a Comment

Peat fires are a global threat to both economies and the environment. They generally burn a smaller area than fast-moving forest fires, but they can burn up to ten times more fuel matter per acre, producing far more smoke and far more carbon emissions. They ignite very easily, are notoriously difficult to put out, all while releasing as much as 100 times more carbon into the atmosphere than flaming fires. Some smoldering peat megafires are the largest and longest burning fires on Earth and are responsible for as much as 15% of annual global greenhouse gas emissions.

Peat fires are known as “zombie fires” because of their ability to hide and smolder underground and then reemerge as new flames days or weeks after they were supposedly extinguished.

Firefighters use billions of gallons of water to tackle a peat fire. For example, fighting the 2008 Evans Road peat fire in North Carolina used up 2 billion gallons of water. When water alone is used to extinguish peat fires, it tends to create large channels in the soil, which diverts water from nearby smoldering hotspots. This is one reason that it is so difficult to extinguish a peat fire.

Researchers at Imperial College London have combined water with an environmentally friendly fire suppressant – one already used on flaming wildfires – and tested its use on peat fires. They found that adding the suppressant to water helped them put out peat fires nearly twice as fast as using water alone, while using only a third to half of the usual amount of water. The suppressant reduces the surface tension of the liquid, making it less likely to create large channels. Instead, the liquid flows uniformly through the soil. This could be an important tool in battling peat fires.

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‘Magical’ fire suppressant kills zombie fires 40% faster than water alone

Photo, posted in August, 2011, courtesy of Chris Lowie / USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.