Rice will lose nutritional value as carbon dioxide levels rise

An international research team led by the University of Tokyo has found that rising levels of carbon dioxide (CO2) will lower the nutritional value of rice.

When rice was grown under the atmospheric conditions that are expected in the second half of this century, iron, zinc, protein, and vitamins B1, B2, B5, and B9 were all reduced.

Study co-author Professor Kazuhiko Kobayashi is an expert on the impacts of air pollution on agriculture.

“Rice is not just a major source of calories, but also proteins and vitamins for many people in developing countries and for poorer communities within developed countries,” said Professor Kobayashi.

People in countries with the highest rice consumption and the lowest gross domestic product could face increasing rates of malnutrition as the nutritional value of rice  and other low-cost foods decline.

However, not all types of rice responded to the experiential conditions in the same way, which means there is a chance that scientists could identify varieties of rice that maintain their nutritional value regardless of CO2 levels.

The rice was grown at research sites in China and Japan, where researchers built 55-foot-wide plastic pipes elevated about a foot above the tops of plants within standard rice fields. Wind speed and direction were measured by a network of sensors and monitors to control how much carbon dioxide was released out of the pipes, which is a technique known as Free-Air Carbon dioxide Enrichment (FACE).

“I first started using this technique in 1998, because we knew that plants raised in a plastic or glass house do not grow the same as plants in normal, open field conditions,” explained Professor Kobayashi.

“This technique allows us to test the effects of higher carbon dioxide concentrations on plants growing in the same conditions that farmers really will grow them some decades later in this century.”

There were some challenges to overcome, such as the interference of wild animals.

“At our first field site, we learned we have to keep all of the pipes and tubes above the ground because raccoons kept chewing through everything and jeopardized the experiment,” said Professor Kobayashi.

Researchers analyzed a total of 18 different varieties of rice to look for protein, iron, and zinc levels, while nine varieties of rice grown in China were used for testing levels of vitamins B1, B2, B5, and B9.

Six hundred million people in regions such as Bangladesh, Cambodia, Indonesia, Lao People’s Democratic Republic, Myanmar, Vietnam, and Madagascar get at least 50 percent of their daily protein directly from rice.

The research is published in the journal Science Advances.

By Chrissy Sexton, Earth.com Staff Writer

Forests and tree-dwelling birds died when dinosaurs vanished

A team of scientists has revealed that dinosaurs were not the only casualty of the catastrophic asteroid event 66 million years ago. The experts have discovered that the world’s forests were also completely destroyed, which caused the extinction of tree-dwelling birds.

Study co-author Regan Dunn is a paleontologist at the Field Museum in Chicago.

“Looking at the fossil record, at plants and birds, there are multiple lines of evidence suggesting that the forest canopies collapsed,” said Dunn.

Lead author Daniel Field explained that the team used a combination of techniques for the investigation.

“We concluded that the temporary elimination of forests in the aftermath of the asteroid impact explains why arboreal birds failed to survive across this extinction event,” said Field. “The ancestors of modern arboreal birds did not move into the trees until forests had recovered from the extinction-causing asteroid.”

Study co-author Antoine Bercovici is a pollen expert at the Smithsonian Institution and the Denver Museum of Nature and Science, Bercovici analyzed microscopic fossils of pollen and spores to determine that the planet’s forests were destroyed.

“After a disaster like a forest fire or a volcanic eruption, the first plants to come back are the fastest colonizers – especially ferns,” said Dunn. This is due to fact that ferns do not sprout from seeds, but from small spores that are made up of just a single cell.

“Spores are minuscule, the size of a grain of pollen, so they’re easily dispersed. They get picked up by the wind and go further than seeds can, and all they need to grow is a wet spot.”

“The spores are tiny – you could fit four across a single strand of your hair. To see them, we take a sample of rock from the time frame just after the collision and dissolve it in acid. Then we purify it so that all that remains is the organic debris, like pollen, spores and little leaf bits, then we look at them under a microscope.”

Immediately after the asteroid collided with the Earth, the fossil record showed the charcoal remains of trees, and then, tons of fern spores.

“Our study examined the fossil record from New Zealand, Japan, Europe and North America, which showed there was a mass deforestation across the globe at the end of the Cretaceous period,” said Bercovici.

The researchers found that the only birds that survived were ground-dwellers. Their fossilized remains contained strong legs like modern ground birds such as kiwis and emus. Tree-dwelling birds have delicate legs that are designed for perching on branches, and they had no place left to live.

“Today, birds are the most diverse and globally widespread group of terrestrial vertebrate animals–there are nearly 11,000 living species,” said Field. “Only a handful of ancestral bird lineages succeeded in surviving the mass extinction event 66 million years ago, and all of today’s amazing living bird diversity can be traced to these ancient survivors.”

Dunn pointed out that fossil plants are critical in reconstructing the history of life on earth.

“Plants are everything, plants are the context in which all terrestrial life evolves and survives. They’re primary producers, they make energy available to all life forms by capturing it from the sun–we can’t do that.”

Dunn also emphasized that the loss of life resulting from the mass extinction 66 million years ago is relevant today.

“The end-Cretaceous event is the fifth mass extinction – we’re in the sixth,” said Dunn. “It’s important for us to understand what happens when you destroy an ecosystem, like with deforestation and climate change–so we can know how our actions will affect what comes after us.”

The study is published in the journal Current Biology.

By Chrissy Sexton, Earth.com Staff Writer

image Credit: Regan Dunn, The Field Museum

One invasive pest species can alter an entire ecosystem

A new long term study has demonstrated how a seemingly harmless single invasive species can cause declines in biodiversity and alter entire ecosystems.

Eastern hemlock, a tree species native to North America, has been facing serious declines due to the hemlock woolly adelgid. The non-native insect hails from East Asia and feeds off the sap of hemlock trees.

The waxy secretions of the pest decrease the growth of Hemlock trees and put a large amount of stress on older trees that can then easily succumb to drought or climate change.

A new study, conducted by researchers from Pennsylvania State University, reveals how invasive adelgids are killing off trees and impacting bird populations that were specialized to the hemlock habitats.

The research was published in the journal The Condor: Ornithological Applications and is one of the most thorough long-term studies examining how tree decline of a single species affects birds and biodiversity.

For the study, the researchers used surveys of Eastern hemlock forests conducted in 2000 before adelgids had caused any decline. Data from the surveys were then compared to new data from the same forests taken in 2015 and 2016.

Native bird species were also considered and the researchers analyzed data showing how different bird populations were affected by the invasive pests.

The researchers discovered that as the Eastern hemlocks declined, specific bird species that are particular to the area also declined and were replaced by other bird species normally found in more general hardwood forests.

“Invasive species, climate change, and land-use change are all similar in that they make our world a less diverse place, and this study helps greatly in understanding how the loss of the eastern hemlock plays its own role in the degradation of biodiversity,” said Morgan Tingley, a professor from the University of Connecticut who was not associated with the research.

The study shows how damaging even just one invasive pest can be and how important conservation efforts are to manage and reduce invasive pests from non-native areas.

“To sum up, to people who are saddened by the loss of hemlocks and the birds that rely on them, I would say one thing: We cannot turn back the clock–we cannot un-introduce the hemlock woolly adelgid; but we absolutely possess the power to prevent this story from repeating itself,” said Matthew Toenies, the study’s lead author.

By Kay Vandette, Earth.com Staff Writer

Image Credit: D Williams

Magic mushrooms help people with depression process emotions

A new study published in the journal Psychopharmacology has found that psilocybin, the main substance in magic mushrooms, may potentially help patients with severe depression process emotions.

Previous research has found that magic mushrooms show promise as a treatment for depression, with one BBC report saying that psilocybin acts like a “lubricant for the mind” and resets the brain.

Magic mushrooms seem to be especially helpful for patients who have not had any success with other traditional medications for anxiety and depression.

The drug helps with changing mood and perceptions, and this recent study conducted by researchers from Imperial College and University College London found that psilocybin was effective for helping depressed patients process and understand others emotions.

Often times, patients with depression are not able to interpret social cues and read expressions as negative.

For the study, researchers administered a psilocybin treatment and psychological support to 17 patients with treatment-resistant depression. 16 control patients were also given a placebo treatment as part of the study.

The participants were shown a series of photographs of 12 male and female actors that had been doctored so each face portrayed an emotion such as happiness, sadness, or anger.

After receiving the psilocybin treatment, the patients were able to read the faces and categorize the emotions. The control patients, however, had no improvement and were not able to read the faces any better.

“Prior to treatment with psilocybin, depressed patients in this trial were shown to have a global deficit in processing emotional faces as compared with healthy controls, as reflected in longer reaction times to identify all emotion types,” the researchers said. “We observed a reaction time improvement post-treatment for all emotion types in depressed patients.”

Magic mushroom treatments are still a long way off, even though some researchers claim they are the safest recreational drug to take.

The study itself was also relatively small and more in-depth research will be needed to better understand how psilocybin affects depression.

By Kay Vandette, Earth.com Staff Writer

Soil microbes communicate and battle with chemical attacks

A handful of soil contains millions of bacteria and fungi, which are competing for space and food. Most are essential in creating healthy soil, but a few of these organisms cause devastating crop diseases. A new study has revealed how some harmful microbes use chemical warfare in response to threats from pesticides as well as from neighboring organisms.

Nancy Keller is a professor of Medical Microbiology and Immunology at the University of Wisconsin-Madison who has studied the interactions among soil pathogens for years, investigating the chemical signals that are sent back and forth among them.

Keller’s team has managed to interpret a signal from the fungal pathogen Fusarium fujikuroi, which responds to an attack by the bacterial wilt species Ralstonia solanacearum by generating a host of antibacterial compounds to defend itself.

“Ralstonia is a lethal wilt pathogen worldwide and attacks over 200 plants,” said Keller. Fusarium species are also a major cause of fungal wilt diseases in crops.

In a previous study, Keller’s students noticed competition between Ralstonia and Fusarium. A closer inspection revealed that Ralstonia caused the nearby fungi to produce chlamydospores, which help the fungus survive stress. The distinctive structures turned a unique shade of rusty red.

In the current study, the team identified the red compound as bikaverin, a chemical that helps prevent infection from bacteria.

The researchers demonstrated that Ralstonia secretes a compound that causes Fusarium to produce chlamydospores. Next, Fusarium produces antimicrobial agents, including the red bikaverin, to protect the chlamydospores from invasion.

The scientists discovered that inhibiting the ability of Fusarium to produce bikaverin allowed Ralstonia to successfully invade the spores.

An unrelated fungal species that is also a damaging plant pathogen, known as Botrytis, genetically acquired the ability to produce bikaverin from Fusarium. Botrytis has the same response to an attack by Ralstonia and produces chlamydospores.

The researchers were surprised to find that Ralstonia could induce bikaverin in both of the fungal species regardless of the environment. Fusarium and Botrytis normally produce the red pigment under very different conditions, primarily based on what nutrients are available.

Keller said that these call-and-response offensive and defensive maneuvers are certainly just a small part of the chemical signals passed between microbes hidden from view.

“How these microbes interact and talk with each other is still in its infancy,” said Keller. “We really don’t know how they talk to each other. And that’s where we want to go in our lab.”

A greater understanding of the messages among the microbial communities in soil could help scientists find ways to respond to persistent threats to crops.

The research is published in the journal mBio.

By Chrissy Sexton, Earth.com Staff Writer

Sweet potatoes are native to Asia, not the Americas, study finds

A study of several plant fossils has uncovered new revelations about the evolutionary history of sweet potatoes, finding that they are not native to the Americas after all.

It had been previously thought that sweet potatoes were native to Central and South America, but although some scientists had argued that the sweet potato plant family actually originated in the Old World and not the Western Hemisphere.

Now, new research conducted by David Dilcher, a paleobotanist from the Indiana University Bloomington has found that sweet potatoes actually came from Asia.

The study was led by Dilcher along with a team of colleagues from India and the results were published in the journal Proceedings of the National Academy of Sciences.

Dilcher and his team studied 57-million-year-old fossils from eastern India that were part of the plant family Convolvulaceae, which includes both morning glory flowers and sweet potatoes.

Although previous fossil evidence pointed to the morning glory family originating in North America, Dilcher discovered that the plant family actually originated much earlier in the late Paleocene epoch in the East Gondwana landmass that would later become part of Asia.

The researchers analyzed 17 fossils from the morning glory family that were discovered in northeastern India. The fossils included both morning glories and nightshade and are the earliest recorded fossils of the morning glory family ever found.

Dilcher and the research team used microscopic analysis of the shape and structure of the leaves to compare the fossil’s leaf veins and cells with other known plants in the same genus.

“We don’t know that these were sweet potatoes,” said Dilcher. “We can’t say there were delicious sweet potatoes there. There may have been, or there may not.”

This method of analyzing plant fossils to better understand evolutionary relationships is a specialty of Dilcher’s.

The fossils were in the Ipomoea genus which contains both sweet potatoes and morning glories, potentially showing that sweet potatoes originated in Asia much earlier than previously realized.

“I think this will change people’s ideas,” said Dilcher. “It will be a data point that is picked up and used in other work where researchers are trying to find the time of the evolution of major groups of flowering plants.”

By Kay Vandette, Earth.com Staff Writer

The secret weapon plants use to battle deadly fungus

Plants can fight back against pathogens that cause disease like a fungus that takes over a fruit or vegetable with gray mold disease.

The way that plants ward off unwanted pathogens is a subject of much interest to researchers as it could help ensure food security.

Both plants and the pathogens that infect them use molecules called small RNAs which are important for invasion and defense.

This process of using RNAs as a defense mechanism is called cross-kingdom RNA interference. Small RNAs can interfere with gene expression and this can work in the favor of the plant when the pathogen takes in small RNAs that inhibit its ability to infect.

A new study conducted by researchers from the University of California, Riverside shows how these RNAs are packaged and delivered from the plant to the pathogen, something that previously had been a mystery.

The results were published in the journal Science.

Hailing Jin, a professor of microbiology and plant pathology at the University of California, Riverside led the study.

The researchers focused on the fungus Botrytis cinerea in order to determine how small RNAs moved across the cellular boundaries between host and pathogen.

After studying infected plants, the researchers found that after being infected with Botrytis cinerea, plant cells package small RNAs inside sacs called exosomes which are delivered from the cells to the site of infection.

The fungus takes in the exosomes and the RNAs stops the disease by inhibiting the expression of certain fungal genes. The researchers call these exosomes “battling bubbles” because of their round shape and effective use as a defense mechanism.

Jin has been working with RNAs,  plant immunity, and disease in an effort to develop effective and eco-friendly ways to control plant diseases that will aid in ensuring food production security.

“The discovery of the role of exosomes in cross-kingdom RNA interference will help us develop effective delivery methods to target plant pathogens with artificial sRNAs, with the goal of controlling plant diseases in crops,”  said Jin.

By Kay Vandette, Earth.com Staff Writer

Image Credit: Rasbak (CC BY 3.0)

Stopping global warming at 1.5°C can save a vast number of species

The effects of global warming are projected to influence climate across the entirety of our planet, changing ecosystems and weather patterns along the way. These changes put many plant and animal species in jeopardy, as they need to adapt more quickly to a less hospitable environment. Now, a new study published in Science has found that limiting global warming to 1.5°C would save the vast majority of the planet’s animal and plant species from climate change.

While past research has focused on quantifying the benefits of limiting warming to 2°C above pre-industrial times, they have not explored how this affects insects. This new research from the University of East Anglia (UEA) is the first to explore how limiting warming to 1.5°C would benefit species globally.

Researchers from UEA and James Cook University in Australia assessed roughly 115,000 species – including 31,000 insects, 8,000 birds, 1,700 mammals, 1,800 reptiles, 1,000 amphibians, and 71,000 plants. Not surprisingly, this is the largest scale study of its kind.

The research team was looking at how different projected climate futures affected areas, making them climatically unsuitable for the plants and animals that live there. “We measured the risks to biodiversity by counting the number of species projected to lose more than half their geographic range due to climate change,” explains Rachel Warren, a professor at UEA and lead researcher on the study. “We found that achieving the ultimate goal of the Paris Agreement, to limit warming to 1.5°C above pre-industrial levels, would reap enormous benefits for biodiversity – much more so than limiting warming to 2°C.”

Their results showed that insects were especially sensitive to climate change. Of the 31,000 insects studied, 18 percent were projected to lose over half their range at a 2°C increase. But at a 1.5°C increase, the number was reduced to 6 percent.

“The current global warming trajectory, if countries meet their international pledges to reduce CO2, is around 3°C,” says Warren. “In this case, almost 50 percent of insects would lose half their range. This is really important because insects are vital to ecosystems and for humans. They pollinate crops and flowers, they provide food for higher-level organisms, they break down detritus, they maintain a balance in ecosystems by eating the leaves of plants, and they help recycle nutrients in the soil.”

Even more concerning, the researchers found that the three biggest groups of pollinating insects were the most sensitive to warming.

In their study, the researchers also assessed the ability of species to relocate to more habitable locations as the climate changes. “If warming is limited to 1.5°C by 2100 then more species can keep up or even gain in range, whereas if warming reached 2°C by 2100 many species cannot keep up and far more species lose large parts of their range,” Warren says.

Although just half-a-degree Celsius may not seem like much, this study shows that there are major consequences that lie between 1.5 and 2°C. If we aren’t able to cut back on the contributing factors to man-made climate change, we might be finding out what those consequences are for ourselves.

By Connor Ertz, Earth.com Staff Writer

Warming climate threatens vast swathes of biodiversity

Average global temperatures are increasing as climate change continues to be a major crisis for our planet. A recent report published in Science, from Rachel Warren at the Tyndall Centre for Climate Change Research at the University of East Anglia in the United Kingdom, found that if global temperature increase cannot be limited to 1.5°C, and rises to 2°C, it just about doubles the risks associated with warming for plants, animals, and insects.

Now, in a reaction to that report, Guy Midgley – a world-leading expert on global change and impact on biodiversity – has published an insight article in Science detailing the effect this temperature change would have on biodiversity.

Warming by more than two degrees will take the world into a temperature state that it hasn’t seen for several millions of years,” says Midgley, a professor in the Department of Botany and Zoology at Stellenbosch University, South Africa.

Based on current pledges by countries for limiting climate change, scientists predict a corresponding warming of roughly 3.2°C. If this were to occur, it’s estimated that the geographic ranges will be lost for 47% of insect species, 26% of vertebrates, and 16% of plant species.

Midgley believes that higher levels of warming may lead to systemic ecological simplification, where many “climate losers” are replaced by far fewer “climate winners.” A simplified ecological landscape could impact ecosystem services such as water quality, soil conservation and flood prevention. If insect populations were to decrease, it would likely mean fewer pollinators – which would be a major loss for plant species and human food production.

“We need to stay as close to 1.5°C as possible. That is really the conclusion from the Warren et al paper,” Midgley says. “So here is the irony. In order to achieve the 1.5°C target, we may well damage many of the habitats that support biodiversity in order to achieve a target that will save biodiversity.” What this means is that, even if governments and industry can limit warming to 1.5°C, recent research shows that large tracts of land would need to be made available for capturing and storing carbon. Expanding land use for carbon storage would likely threaten the habitats that occupy this land.

“There is way too much debate about the issue of climate change and whether or not it is real,” laments Midgley. “What we really need to be doing is debating how we solve this problem…  if we fail to reduce our dependence on fossil fuels, we could literally move the world back 20 to 30 million years in the space of a century.”

By Connor Ertz, Earth.com Staff Writer

Many diverse tropical species can find their roots in the Amazon

A new study has found that many diverse tropical species now found in Latin America originated in Amazonian rainforests.

The American tropics are one of the most biodiverse areas on the planet, with many unique species found nowhere else in the world.

An international team of researchers led by Harvard Visiting Scholar Alexandre Antonelli identified the processes by which many species first colonized and evolved in Latin America, leading to a thriving ecosystem with unrivaled species diversity.

The study is published in the journal Proceedings of the National Academy of Sciences.

“We were astonished to detect so much movement across such different environments and over such large distances,” said Antonelli, the study’s lead author. “Up until now, these natural dispersal events were assumed to be quite rare. Our results show how crucial these events have been in the formation of tropical America’s unique and outstandingly rich biodiversity.”

Species have naturally come to colonize different regions and it’s a process that has taken tens of millions of years.

The plants and animals that migrated away from their original area had to learn to adapt to different conditions and over time, these species evolved into completely different species in their new environment.

This process is exactly why the American Tropics are so diverse compared to other regions around the world and the researchers wanted to better understand what mechanisms drive species distribution.

“Most evolutionary research focuses on how new species form,” said Antonelli. “But we want to understand how whole ecosystems evolve, and what makes some regions much more species-rich than others. This is important because it shows us how plants and animals deal with new environments and what factors determine biodiversity.”

The researchers collected an expansive amount of data on evolutionary relationships, distribution, and timing of the origin of thousands of tropical species in order to calculate the frequency that species were distributed to a different region.  

Birds, frogs mammals, snakes, lizards, and plants were all considered for the study.

Among all the regions in the American tropics that have distributed species, Amazonia was the main source of many of the species in the area.

“Two main factors seem to explain the key role of Amazonia in exporting so much diversity: its huge area, and the large amount of time that species have existed there,” said Antonelli. “Together, these have increased the chances of species dispersing into new habitats and regions.”

Besides proving the key role that Amazonia played in the biodiversity of the American Tropics, the study shows the danger that many tropical ecosystems face due to human activities.

“Biodiversity is the dark matter of our planet: we know there must be millions of species that we haven’t found yet,” said Antonelli. “Finding, understanding, and protecting this diversity is probably humanity’s toughest but most important challenge”

By Kay Vandette, Earth.com Staff Writer

Seasonal allergies intense? Climate change may be to blame

If you think your seasonal allergies are worse than usual this year, you may be right – and climate change seems to be behind it.

Climate scientists have been recording earlier starts to spring, warm winters with more rain and snow, and longer growing seasons, which leads to more pollen in the air longer, they said. For the more than 50 million Americans who struggle with seasonal allergies, that’s bad news.

“Some research has suggested that the warming trend that we have in our environment is causing the pollen seasons to start a little bit earlier, and extend a little bit longer,” said Dr. Stanley Fineman, a Georgia allergist and immunologist, told NBC News.

That longer pollen exposure means allergy sufferers are battling symptoms longer, said Fineman, is is a past president of the American College of Allergy, Asthma and Immunology.

The claims are backed by research into seasonal changes in the United States over the past few years.

Between 1995 and 2011, the pollen season around the U.S. grew longer by 11 to 27 days, according to a report released by the Allergy and Asthma Foundation of America. Increased atmospheric carbon encourages plants like ragweed to grow faster and larger, the report noted. Higher carbon levels can actually make pollen that produces a stronger allergic reaction among people who suffer seasonal allergies, the researchers found.

Warming temperatures can affect the protein composition of pollen and fungal spores, the American Academy of Allergy Asthma & Immunology writes on its website. Changes in weather patterns can also affect how pollen spreads.

Tree pollen is also exploding. A video that captured the massive pollen release of a pine tree in Cumberland County, New Jersey went viral this week after it was posted on Facebook.

In 2014, a team of climate experts around the country recorded observations about changing climate conditions all over the country. They found that the rise of average global surface temperatures were having an effect inside the U.S.

“Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours,” the team wrote in their peer-reviewed National Climate Assessment. “People are seeing changes in the length and severity of seasonal allergies, the plant varieties that thrive in their gardens, and the kinds of birds they see in any particular month in their neighborhoods.”

And while much of the focus this time of year is on seasonal allergies caused by pollen, warmer and wetter winters can also lead to more fungal growth. Fungal spores are another irritant.

“Flooding and severe storms can result in damp buildings and resultant mold exposure,” the AAAAI website said. “In addition to triggering allergic reactions, increased mold spore exposures have been linked to other lung diseases.”

This spring, there has been a huge jump in the number of people who are suffering seasonal allergies for the first time, the organization told NBC.

Symptoms of seasonal allergies – also called hay fever or allergic rhinitis – include itchy, burning or watery eyes; itchy, stuffy or runny nose; sneezing; and itching of the roof of the mouth. In some cases, seasonal allergies can lead to allergic asthma, which can cause coughing, wheezing and inflamed airways. Seasonal allergies can also raise the risk of sinus infections, bronchitis and other respiratory illnesses.

Anyone experiencing symptoms of allergies or allergic asthma should consult their doctor about relief strategies, from home treatment to over-the-counter or prescription medications.

Allergy sufferers should avoid pollen during the growing season, by exercising indoors, closing windows and using an air conditioner as needed.

By Kyla Cathey, Earth.com staff writer

Mixed forests are more economically and ecologically valuable

Forests with a diverse mix of plants and trees are more productive than forests with only a single kind of species, also known as a monoculture.

Mixed forests do better on all five of the Earth’s continents but still, many forest managers are unconvinced, sticking to monocultures.

That is why researchers from the Technical University of Munich (TUM) conducted an expansive international overview study reviewing research on mixed forest productivity in order to aid in future forest management on a global scale.

“We know of the many advantages of mixed forests,” said Hans Pretzsch, a co-author of the study. “Mixed-species forests are ecologically more valuable as versatile habitats. They mitigate climate change, as they mean a higher carbon sink.”

The researchers reviewed 600 studies that examined why mixed forests were more productive. Of those 600, the researchers filtered out 126 case studies from 60 areas around the world from 1997 to 2016.

Long-term studies, which the 126 were, make for better research because measurements and data come from years of record keeping which provides a more accurate picture of how environments respond to different factors.

Many of the studies were conducted in Bavaria, some of which are the oldest forestry experiments in the world. Experimental areas with mixed forests and monocultures in Bavaria were first set up in the 1870s and measurements are still taken today.

After analyzing the data, the researchers discovered that trees in mixed forests have better access to light, water, and soil nutrients compared to monocultures. The complex network of root systems compliment each other which allows for better absorption with mixed species.

“This makes mixed stands more resilient during dry years. In addition, they are more stable against pests and visually more appealing,’ said Pretzsch.

The researchers say that the results show that choosing a combination of tree species creates more resilient and productive forests.

“Based on these findings, the interactions between the individual tree species will be studied in more detail at the TUM,” said Pretzsch.

In order to do this, the researchers will expand the Bavarian plots to include more than a hundred hectares of mixed stand experiments.

“This will be highly interesting for science and provide practical decision-making aids,” said Pretzsch. “In light of climate change and the increasing ecological, economic, and social requirements that forests need to fulfill, mixed stands will increase in importance throughout the world.”

By Kay Vandette, Earth.com Staff Writer

Image Credit: Photo: L. Steinacker/Technical University of Munich (TUM)