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Mining with plants

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Plants absorb nutrients and minerals from the soil as they grow and incorporate them into their leaves and stems.  Such plants can be used to remove toxic elements from soil.  Cleaning soil in this way is called phytoremediation. 

Researchers at the University of Massachusetts Amherst are trying to go beyond phytoremediation and do phytomining, in which hyperaccumulated minerals from the soil can be harvested from plants for use in industrial or manufacturing applications.

One mineral that is critically needed for modern technology is nickel.  There are trace amounts of nickel in nearly one million acres of topsoil in the US, making the soil inhospitable for most crops, but the economics and environmental impact of extracting it make doing it impractical. 

A common plant, Alyssum murale, is a nickel hyperaccumulator; in fact, up to 3% of the plant’s biomass can be made up of nickel.  But the plant is slow-growing and difficult to manage and is also considered an invasive species

Another common plant, Camelina sativa, does not have the downsides associated with Alyssum and is also a rich source of valuable biofuel.  The Amherst researchers are working to determine which genes and proteins are responsible for Alyssum’s nickel hyperaccumulation and hope to genetically engineer Camelina sativa to have the same ability.

The researchers believe there is enough nickel in barren soil in the US to supply 50 years of phytomining.  It wouldn’t supply all the nickel the economy needs, but it could account for 20 to 30 percent of the projected demand.

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Scientists at UMass Amherst Engineer Plant-based Method of ‘Precious’ Mineral Mining

Photo, posted July 10, 2017, courtesy of Matt Lavin via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Engineering plants to consume more carbon dioxide

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The most abundant protein on the planet is an enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase, better known as RuBisCO.  Its critical role in photosynthesis makes life as we know it on earth possible.  What it does is convert carbon dioxide from the atmosphere into the organic matter contained in plants.

Getting plants to take up more carbon dioxide from the atmosphere is a key strategy for mitigating climate change.  Planting lots of trees is one way to do it.  Another is to get individual plants to capture more carbon dioxide.

Scientists at the University of Illinois have focused on getting plants to produce more RuBisCO which allows them to grow faster, consuming more carbon dioxide in the process.

Some plants are better than others at taking advantage of the earth’s rising carbon dioxide levels.  Among these are food crops like corn, sugarcane, and sorghum.  Such plants’ growth is not primarily limited by how much carbon dioxide is in the atmosphere but rather by how much RuBisCO is in their leaves.  The Illinois scientists tweaked genes in corn and sorghum to produce plants containing more RuBisCO.  Laboratory experiments on corn demonstrated faster corn growth.  Recent outdoor field experiments on sorghum demonstrated a 16% boost in its growth rate. 

Improving photosynthesis in this way is not only a potential strategy for increasing plants’ ability to combat climate change.  It is also a way to cope with the world’s increasing demand for food by producing crops that can grow larger and more quickly.

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Scientists Engineer Crops to Consume More Carbon Dioxide

Photo, posted April 12, 2016, courtesy of K-State Research and Extension via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Growing safer potatoes

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We are often advised to avoid eating green areas on potatoes.  The green comes from chlorophyll that occurs naturally when potatoes are exposed to light.  It is harmless but when it is there, it can be accompanied by a natural toxin – a substance called solanine, which is a steroidal glycoalkaloid or SGA.  Sunlight can produce solanine as well as chlorophyll.  Solanine is produced by plants to protect them from insects. 

Solanine is bitter tasting so one is unlikely to consume much of it.  But consuming enough of it can lead to gastrointestinal complications like diarrhea, abdominal pain, vomiting, and sweating. 

Researchers at the University of California Riverside have discovered a way to eliminate toxic compounds from potatoes, making them safer to eat and easier to store.  They have identified a key genetic mechanism in the production of SGAs.  They found a specific protein that controls the production and believe it will be possible to control where and when SGAs are produced.  Thus, it may be possible to have SGAs present in the leaves of potato plants, thereby protecting them from insects, while having none in the potatoes themselves.  By limiting SGAs to non-edible parts of plants, they can be safer and more versatile plants.  For example, modified potatoes could be stored in sunny places without worry and would always be safe to eat.

Plants have evolved ingenious ways to balance growth, reproduction, and defense.  Our growing understanding of these mechanisms can allow people to redesign crops to meet modern needs, increase food safety, and reduce food waste.

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Growing safer spuds: Removing toxins from potatoes

Photo, posted October 14, 2013, courtesy of Elton Morris via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A dangerous invasive species

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Weeds are the bane of every gardener’s existence.  They pop up, uncontrolled and unwelcome, and must be tediously managed time and time again.  But in some cases, weeds are more than just a nuisance.  Some are a public health hazard. 

Meet giant hogweed.  Native to Europe’s Caucasus Mountains, giant hogweed belongs to the carrot family. The plant resembles Queen Anne’s Lace – on steroids. Giant hogweed can grow up to 15 feet tall with three inch stems, five-foot-wide leaves, and an umbrella-like canopy of white flowers.

Botanists brought giant hogweed to England as an ornamental plant in the 1890s.  It made its way to the U.S. via horticultural channels.  In fact, one of the first specimens was planted in a Victorian garden near Rochester, NY.  

As with most invasive plants, it quietly escaped cultivation. In the U.S., giant hogweed can be found in New England, the Mid-Atlantic Region, and the Northwest, with plants preferring moist habitat near roadside ditches and stream banks.   

While a seemingly innocent flowering plant, giant hogweed is actually one of the most hazardous plants in the U.S.  Brushing against or breaking the plant releases sap that, when combined with sunlight and moisture, can cause severe burn-like lesions, blistering sores, and purplish or blackened scars.  Getting sap in your eyes can result in temporary or even permanent blindness.

With each plant dropping up to 120,000 seeds, it’s no surprise that giant hogweed is proving difficult to eradicate.

If you suspect giant hogweed is growing near you, photograph the plant from a safe distance and report the sighting to local environmental authorities. 

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Plant Pest Risk Assessment for Giant Hogweed

Giant Hogweed

Photo, posted March 22, 2021, courtesy of Scottish Invasive Species Initiative via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Where not to plant trees

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Planting huge numbers of trees is often proposed as a way to reduce the severity of climate change.  Studies have looked at the potential for Earth‘s ecosystems to support large additional areas of forest and have found that it would be possible to have at least 25% more forested area than we do now.  This in turn could capture large amounts of carbon and substantially reduce the amount in the atmosphere.

A recent study by researchers at Clark University in Massachusetts and The Nature Conservancy mapped the climate impact of tree planting across the globe, identifying where it would be most and also least beneficial.  The study, published in Nature Communications, found that trees planted in arid, desert regions or in snowy places like the Arctic would, on balance, worsen warming rather than reduce it.

Trees take up carbon dioxide from the atmosphere, which helps to keep warming in check.  But trees with dark, green leaves also absorb heat from sunlight.   Snow and desert sand, on the other hand, are light-colored and reflect more sunlight back into space.  For this reason, trees planted in snowy areas or in the desert will absorb more sunlight than their surroundings.  This can negate the climate benefits of soaking up carbon dioxide.

Previous studies only looked at how much carbon dioxide would be removed by planting trees in order to determine how much warming would be prevented.  The new study finds that it matters where the trees are planted.

Fortunately, the new study also shows that tree planting projects that are currently underway or that are in the pipeline are largely concentrated in regions where they will indeed help slow global warming.

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This Map Shows Where Planting Trees Would Make Climate Change Worse

Photo, posted April 5, 2022, courtesy of UC Davis Arboretum and Public Garden via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Detecting dangerous chemicals with plants

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Researchers at University of California Riverside have been studying how to enable plants to sense and react to a chemical in the environment without damaging their ability to function in all other respects.  Why do this?  The idea is to be able to use plants as environmental sensors that can detect the presence of harmful substances.

The impetus for the work is presence of a protein in plants that senses a plant hormone called abscisic acid (or ABA) that helps plants acclimate to environmental changes.  During drought, plants produce ABA causing the plant to produce ABA receptor proteins that close pores in its leaves and stems, keeping in moisture.

The UCR researchers demonstrated that these ABA receptor proteins can be trained to bind to chemicals other than ABA.  This ability enabled them to create sensors for many chemicals, including banned pesticides.

In their recent publication, they demonstrated a green plant that turns bright red in the presence of azinphos-ethyl, a banned pesticide.  The goal is to easily detect chemicals in the environment from a distance.  A field of these plants would provide an obvious visual indicator of the use of a banned pesticide.  The researchers also demonstrated the ability to turn a variety of yeast into a sensor that could respond to two different chemicals at the same time.

Ultimately, it would be extremely valuable to design plants that sense dozens of chemicals to they could be used as living sensors that persist for years and provide environmental information.  The sensor plants are not being grown commercially at this time.  That will require regulatory approvals that are likely to take years.  But the discovery opens up real possibilities.

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Plants transformed into detectors of dangerous chemicals

Photo, posted August 29, 2013, courtesy of the United Soybean Board via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Liquid Fuel From Sunshine | Earth Wise

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A key goal of artificial photosynthesis research is to be able to produce a useful liquid fuel using only carbon dioxide, water, and sunlight in a single step.  Such a so-called solar fuel would produce net zero carbon emissions and would be completely renewable.

Bioethanol has long been touted as a green alternative to fossil fuels, since it is made from plants rather than petroleum.  But producing it takes up agricultural land that could be used to grow food instead and there are emissions associated with many aspects of the process by which plant mass becomes fuel.

Researchers from the University of Cambridge in the UK have developed a so-called artificial leaf that produces ethanol or propanol – usable liquid fuels – in a single step.  They developed a copper and palladium-based catalyst that allows the artificial leaf to directly produce multicarbon complex chemicals.  Earlier versions of artificial leaves could make simple chemicals, such as syngas, which would then require additional processing to turn into high-density fuels.

The new device produces liquid fuel from carbon dioxide and water simply by shining sunlight on it.

At present, the artificial leaf is a proof-of-concept device that exhibits only modest efficiency.  The researchers are working to optimize the device’s light absorbers so that they can better make use of sunlight and to optimize the catalyst so that it can convert more of the sunlight into fuel.  In addition, the device needs to be scaled up so that it can produce large volumes of fuel.

All that being said, it is an important step towards people being able to do what plants have been doing for millions of years.

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Driving on sunshine: clean, usable liquid fuels made from solar power

Photo, posted March 23, 2015, courtesy of Astro via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Mercury In The Amazon Rainforest | Earth Wise

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Recent research has found that some of the highest levels of mercury pollution ever recorded are in a patch of pristine Amazonian rainforest.  The international team of researchers discovered that illegal goldmining in the Peruvian Amazon is the source of the pollution.

Illegal miners separate gold particles from river sediments using mercury.  Mercury binds to gold, forming pellets large enough to be caught in a sieve.   The pellets are then burned in open fire ovens, releasing the mercury to the atmosphere, leaving the gold behind.  The mercury smoke ends up being washed into the soil by rainfall, deposited onto the surface of leaves, or directly absorbed into leaf tissues.

Deforested areas had low levels of mercury, while the areas with the largest, densest old-growth trees captured huge volumes of atmospheric mercury, more than any other ecosystem studied in the entire world.  Mercury levels were directly related to leaf area index:  the denser the canopy, the more mercury it holds.  Birds from this area have up to twelve times more mercury in their systems than birds from less polluted areas.  Such high concentrations of mercury could provoke a decline of up to 30% in these birds’ reproductive success.

Small-scale artisanal gold mining is an important livelihood for local communities.  Eliminating it outright may not be a viable solution but coming up with ways to continue to provide a sustainable livelihood while protecting communities from poisonous pollution is essential.

In the meantime, the forests are doing an important service by capturing much of the mercury and preventing it from getting into the general atmosphere and endangering more people and animals.  Burning or harvesting the mercury-ridden trees would release the mercury back into the atmosphere.

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Modern Day Gold Rush Turns Pristine Rainforests into Heavily Polluted Mercury Sinks

Photo, posted August 24, 2016, courtesy of Anna and Michal via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Importance Of City Trees | Earth Wise

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It is well known that green spaces can improve the quality of life and create a better climate in cities.  City trees and vegetation can help reduce urban heat island effects by shading buildings and roads, deflecting radiation from the sun, and releasing moisture into the atmosphere.  City trees and green spaces have also been proven to increase property values, promote wildlife and plant diversity, reduce noise pollution, and improve human health.  But how important are trees and vegetation for producing cleaner air in cities?

According to a new study led by researchers at the University of Gothenburg in Sweden, trees do contribute to cleaner air in cities, but the degree to which they do so varies greatly between different locations. 

The research team measured air pollutants across seven urban settings in the city of Gothenburg, and compared them with pollutants on the leaves of deciduous trees.  The researchers chose to focus on polycyclic aromatic hydrocarbons (PAHs), which are pollutants generated primarily during the incomplete combustion of organic materials, like coal, oil, and wood.

The results revealed that the pollutants in leaves did increase over time.  The researchers were able to show a clear correlation between the level of air pollutants and the concentration of pollutants in leaves. 

But at the same time, the researchers discovered that pollution levels varied greatly between measurement sites.  For example, the levels of PAHs were seven times higher at the most polluted site (the city’s main bus station) than they were at a location on the periphery of the city.

The research team hopes its findings will be used to help guide the planning of future urban landscapes.

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Trees are important for cleaner air in cities

Photo, posted November 5, 2021, courtesy of Maria Eklind via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Potential Of Artificial Photosynthesis | Earth Wise

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The sun is the primary source of energy on the earth.  Enough solar energy hits the earth in one hour to meet all of human civilization’s energy needs for an entire year.  The two leading forms of renewable energy – photovoltaic solar power and wind power – are ways of making use of the sun’s energy.  Wind power is indirectly provided by the sun; photovoltaic power uses sunlight to generate electricity.

The most efficient use of solar energy on the planet is one perfected by plants millions of years ago:  photosynthesis.  Photosynthesis is a complex sequence of processes by which plants convert sunlight and water into usable energy in the form of glucose.  Plants utilize a combination of pigments, proteins, enzymes, and metals to perform their magic.  If we can develop artificial photosynthesis, it would be a dramatic improvement of humans’ ability to power society cleanly and efficiently.  Whereas photovoltaics capture about 20% of the sun’s energy, photosynthesis stores 60% of the sun’s energy as chemical energy.

Researchers across the globe are working to develop artificial photosynthesis.  A group at Purdue university has been making progress in trying to mimic the ability of leaves to collect light and split water molecules to generate hydrogen. This is a critical step in photosynthesis that is accomplished by protein and pigment complexes known as “photosystems II”.  The Purdue group is experimenting with these proteins and various synthetic catalysts in order to try to develop artificial leaves based on abundant, nontoxic materials. 

It is likely to take a decade or more for artificial photosynthesis technology to become part of our energy system, but its ultimate potential is enormous.

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Soaking up the sun: Artificial photosynthesis promises a clean, sustainable source of energy

Photo, posted June 14, 2007, courtesy of Alex Holyoake via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Turning Atmospheric Carbon Into Useful Materials | Earth Wise

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Plants have the ability to capture carbon dioxide from the atmosphere and incorporate it into leaves, fruits, wood, and other plant materials.  This beneficial process is mostly temporary, as much of this carbon dioxide from plant matter ends up back in the atmosphere through decomposition, or even burning.

Researchers at the Salk Institute have proposed a more permanent fate for captured carbon by turning plant matter into a valuable industrial material called silicon carbide.

In a recent study published in the journal RSC Advances, Salk scientists transformed tobacco and corn husks into silicon carbide and evaluated and quantified the benefits of the process.

The researchers used a previously reported method to transform plant matter into silicon carbide in three stages and carefully tracked the carbon utilization at each stage.

Stage one is growing the plants.  They used tobacco from seed, chosen for its short growing season.  Then the harvested plants are frozen, ground into a powder, and treated with chemicals including a silicon-containing compound.  Finally, the powder is subjected to a high-temperature process resulting in the production of silicon carbide.

Their analysis showed that much of the carbon sequestered by growing the plants could be preserved through the full process and the amount of energy required for the production of the silicon carbide (mostly from the high-temperature process) is comparable to current manufacturing processes for the material.

Permanently sequestering carbon from agricultural waste products by incorporating it into a valuable industrial material would be a valuable addition to strategies for reducing greenhouse gases in the atmosphere.

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Transforming Atmospheric Carbon Into Industrially Useful Materials

Photo, posted August 3, 2013, courtesy of AJ Garrison via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Forests And Climate Change | Earth Wise

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A carbon sink is anything that absorbs more carbon from the atmosphere than it releases.  Examples of carbon sinks include the ocean, soil, and plants.  In contrast, a carbon source is anything that releases more carbon into the atmosphere than it absorbs.  Volcanic eruptions and burning fossil fuels are two examples.

Forests are among the most important carbon sinks.  Trees remove carbon from the air and store it in their trunks, branches, and leaves, and transfer some of it into the soil.  But in many regions, deforestation, forest degradation, and the impacts of climate change are weakening these carbon sinks. As a result, some climate activists advocate for large-scale tree-planting campaigns as a way to remove heat-trapping CO2 from the atmosphere and help mitigate climate change. 

But according to a new study recently published in the journal Science, planting new trees as a substitute for the direct reduction of greenhouse gas emissions could be a pipe dream.  While planting trees is easy, inexpensive, and can help slow climate warming, the ongoing warming would be simultaneously causing the loss of other trees.  Instead, the research team says it makes more sense to focus on keeping existing forests healthy so they can continue to act as carbon sinks, and to reduce emissions as much as possible and as quickly as possible.        

But keeping forests healthy will require a paradigm shift in forest management.  Instead of trying to maintain forests as they were in the 20th century, the research team says forests need to be managed proactively for the changes that can be anticipated. 

One thing is clear: We cannot plant our way out of the climate crisis.

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Forests and climate change: ‘We can’t plant our way out of the climate crisis’

Photo, posted August 9, 2015, courtesy of Nicholas A. Tonelli via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Why Do Trees Change Color? | Earth Wise

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We had a particularly colorful fall in the Northeast this year.  Almost everywhere you looked, there were brilliant displays of yellow, orange, and red.  The colors of fall are a result of chemistry and environmental events that may have taken place many months in the past.

The color of leaves comes from 4 pigments whose effects are governed by photosynthesis.  The one that is actually used in photosynthesis is chlorophyll and it causes leaves to be green.  But when a tree begins to prepare for dormancy, it stops producing chlorophyll, the green pigmentation fades, and the other pigments that were already in the leaves become visible.

There are xanthoplylls, which are the yellow pigments that are seen the most in fall trees.  They are the same pigments that color egg yolks and sometimes parts of the human eye.  They are only produced by plants and appear in humans and animals only through consumption.

There are carotenes, which are the orange pigments found in fruits and vegetables, such as carrots, oranges, some bell peppers and squashes.

And there is anthocyanin, which is the pigment found in blueberries, blackberries, and red or violet roses.  Its color depends on the pH level of the plant; higher pH leads to darker color.  This is the pigment seen in red maples, black cherry trees, Shumard oaks, and more.  Only 10% of trees in temperate climates produce anthocyanin and its red pigmentation and most of those trees are in New England.

All these pigments serve purposes.  They help trees absorb light energy, prevent sun damage, and even regulate how much energy chlorophyll produces.

There are complicated chemical and environmental factors at play in fall foliage but when they come together like they did this year, it’s a magnificent spectacle.

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Why Do Trees Change Color?

Photo, posted October 17, 2020, courtesy of John Brighenti via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Restoring Seagrass In Virginia | Earth Wise

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Seagrass is found in shallow waters in many parts of the world.  They are plants with roots, stems, and leaves, and produce flowers and seeds.  They can form dense underwater meadows that constitute some of the most productive ecosystems in the world.  Seagrasses provide shelter and food to a diverse community of animals including tiny invertebrates, fish, crabs, turtles, marine mammals and birds.

In the late 1920s, a pathogen began killing seagrasses off the coast of Virginia.  In 1933, a hurricane finished them off completely.  For nearly 70 years thereafter, the bay bottoms of the Virginia coast were muddy and barren, essentially devoid of fish, shellfish, mollusks and other creatures that inhabit seagrass meadows.  The local scallop industry was no more.

The largest seagrass restoration project ever attempted has changed all that.  During the past 21 years, scientists and volunteers have spread more than 70 million eelgrass seeds within four previously barren seaside lagoons.  This has spurred a natural propagation of meadows that have so for grown to almost 9,000 acres, the largest eelgrass habitat between North Carolina and Long Island Sound.

The long-term research conducted by the team from the University of Virginia shows that the success of the seagrass restoration project is improving water quality, substantially increasing the abundance of fish and shellfish in the bays, and capturing carbon from the water and atmosphere and storing it in the extensive root systems of the grasses and in the sediment below. 

The study shows that marine restorations are possible on scales that contribute directly to human well-being.

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Some Good News: Seagrass Restored to Eastern Shore Bays is Flourishing

Photo, posted May 17, 2019, courtesy of Virginia Sea Grant via Flickr. Photo credit: Aileen Devlin | Virginia Sea Grant.

Earth Wise is a production of WAMC Northeast Public Radio.

Planting Trees and Climate Change | Earth Wise

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Forests are among the most important natural carbon sinks.  Trees remove carbon from the air and store it in their trunks, branches, and leaves, and transfer part of it into the soil.  But in some regions, these natural carbon sinks are starting to weaken due to deforestation, forest degradation, and the impacts of climate change.  This problem has led some climate mitigation projects to focus on increasing the overall number of trees on the planet. 

But, according to a paper recently published in the journal Science, “we can’t plant our way out of climate change.”  That’s the simple message from Restoration Ecologist Karen Holl and University of São Paulo Professor Pedro Brancalion to anyone who thinks planting one trillion trees will reverse the effects of climate change.  They say planting more trees is only one piece of the puzzle.  Any initiatives like 1t.org or the Trillion Tree Campaign must be done carefully and be accompanied by commitments to long-term management.

Tree plantings can provide many environmental benefits, including improving water quality, biodiversity, and increasing shade.  But trees can sometimes have undesirable impacts, such as harming native species and ecosystems or reducing water availability, depending on where and how the trees are planted.

The authors suggest four principles that should guide forest enhancement initiatives: reduce forest clearing and degradation, balance ecological and social goals, view tree plantings as one part of a multifaceted solution, and plan, coordinate and monitor the work. 

While tree plantings can clearly be part of the solution, slowing the pace of climate change requires a comprehensive approach that must start with burning less fossil fuels.

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Challenges in tree-planting programs

Planting trees is no panacea for climate change

Photo, posted December 1, 2019, courtesy of Akuppa John Wigham via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Narwhal Tusks And Stories Teeth Can Tell | Earth Wise

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Teeth and particularly narwhal tusks are getting some unusual press recently when one of them was the weapon of choice to fend off the London Bridge attacker, which was a good choice according to Harvard dental researcher Dr. Martin Nweeia.  Turns out that narwhal tusks have some pretty amazing physical features.  They exhibit both extreme strength and flexibility at the same time.  The narwhal is known as the unicorn of the sea, a pale-colored, medium-sized whale found in Arctic coastal waters and rivers.  In males, the more prominent tooth grows into a sword like, spiral tusk up to 8.8 feet long.

Changes in the shape of teeth over time can tell us about climate change. Adaptations in horse teeth 55 million years ago from North America were observed and caused by changes in climate, favoring different food sources.  The horses changed their diets from fruit to more favorable grasses and their teeth changed in response. For this same reason, the teeth of elephants adapting in different environments of Asia and Africa have different tooth forms.  Both eat plants but Asian elephants, with more ridges on their teeth, eat larger amounts of grasses while African elephants, with wider spread ridges, eat more leaves. 

Teeth have been used to link land mass theories like the Bering Land Strait Theory, hypothesizing that North America and Asia were once one land mass. The teeth shape and form of people on both sides of the Bering Land Bridge shared a common “mongoloid dentition” with unique features. And so, can the narwhal tusk tell us something about a changing Arctic?  Scientists have discovered that the narwhal tusk is a giant sensory organ that is able to continually monitor its environment and has the ability to detect ice formation, and melt, both capabilities helpful for surviving in a changing Arctic.

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–Earth Wise acknowledges script contribution from Dr. Martin Nweeia of Harvard University.

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Fossil teeth reveal new facts about a mass extinction 260 million years ago

From the Horse’s Mouth: Teeth Reveal Evolution

Photo, posted April 3, 2019, courtesy of James St. John via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Bees And Plastic

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Wild bees in Argentina have recently been found to be constructing nests entirely made of flimsy plastic material left on farms and scientists don’t know why.

In 2017 and 2018, researchers at Argentina’s National Agricultural Technology Institute built wooden, artificial nests for wild bees.  These bee species burrow into nests to individually lay larvae rather than having a large hive with queens and workers.  The artificial nests provide hollow openings that bees generally fill with cut leaves, twigs, and mud.

Sixty-three wooden nests were constructed and three were found lined entirely with plastic.  The bees carefully cut bits of plastic in the shape and size of fingernails and arranged them in an overlapping pattern in their nests.  The plastic seems to have come from plastic bags or films, which have a similar texture to the leaves bees ordinarily use to line their nests.  And, in fact, leaves were readily available to the bees making use of plastic.

This is the first time that bees have been seen making nests entirely out of plastic, but for years scientists have known bees were incorporating plastic into their building materials.  Research is needed to determine the potential impact plastic might have on bees, but the nest building shows that bees are highly adaptive to changing environments.

Plastic often forms a threat to wildlife in the form of microplastics that can be consumed.  But there is no evidence that bees are consuming plastic.  Some researchers have speculated that the plastic in bees’ nests may form a barrier against common nest issues like mold and parasites.

At this point, it is not clear whether it is a good thing or a bad thing that some bees are choosing plastic over natural materials, but it is certainly interesting.

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Wild bees are building their homes from plastic—and scientists aren’t sure why

Photo, posted December 12, 2014, courtesy of Judy Gallagher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Trees And The Future Of Cities

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The shade of a single tree is a welcome source of relief on a hot summer day.  But even a relatively small patch of woods can have a profound cooling effect.  A new study at the University of Wisconsin-Madison looks at the role trees play in keeping towns and cities cool.

According to the study, the right amount of tree cover can lower daytime temperatures in the summer by as much as 10 degrees.  The effects are noticeable from neighborhood to neighborhood and even on a block-by-block basis.

Cities are well-known to be hot spots due to the urban heat islanding effect.  Using trees to keep temperatures more comfortable in cities can make a big difference for the people who live and work there.

The man-made structures of cities – roads, sidewalks, and buildings – absorb heat from the sun during the day and slowly release it at night.  Trees, on the other hand, not only shade those structures from the sun, but they also transpire -or release water in the air through their leaves – which helps to cool things down.

According to the study, to get maximum cooling benefits, tree canopies must exceed forty percent, meaning that city blocks need to be nearly halfway covered by tree branches and leaves.  To get the biggest bang for the buck, cities should start planting more trees in areas that are already near the forty percent threshold.  But

trees can’t just be in parks.  They need to be in places where people are active.

If we want the places where we live to be more comfortable and resilient in a warming world, we need to plant more trees.

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Study suggests trees are crucial to the future of our cities

Photo, posted May 26, 2012, courtesy of Mislav Marohnic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving Beaches With Seagrass

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Almost a quarter of the Gross Domestic Product of places around the Caribbean Sea is earned from tourism.  Preserving the beaches in the region is an economic imperative.  With increasing coastal development, the natural flow of water and sand is disrupted, natural ecosystems are damaged, and many tropical beaches simply disappear into the sea.

With such high stakes, expensive coastal engineering efforts such as repeated replenishing of sand and the construction of concrete protective walls are common strategies.  Rising sea levels and increasingly powerful storms only increase the threat to tropical beaches.

Researchers from The Netherlands and Mexico recently published a study in the journal BioScience on the effectiveness of seagrass in holding onto sand and sediment along shorelines.

Seagrasses are so-named because most species have long green, grass-like leaves. They are often confused with seaweeds but are actually more closely related to flowering plants seen on land. Seagrasses have roots, stems and leaves, and produce flowers and seeds. Seagrasses can form dense underwater meadows and are one of the most productive ecosystems in the world. Seagrasses provide shelter and food to an incredibly diverse community of animals, from tiny invertebrates to large fish, crabs, turtles, marine mammals and birds.

The researchers performed measurements of the ability of seagrass along Mexico’s Yucatan Peninsula coastline to keep sand in place and prevent erosion.  They found that the amount of erosion was strongly linked to the amount of vegetation.  Quite often, seagrass beds have been regarded as a nuisance, rather than a valuable asset for preserving valuable coastlines.  The study opens opportunities for developing new tropical beach protection schemes in which ecology is integrated into engineering solutions.

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Seagrass Saves Beaches and Money

Photo, posted October 13, 2010, courtesy of NOAA via Flickr.

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