weeds

Elephants And Global Warming | Earth Wise

March 9, 2023 By EarthWise Leave a Comment

A study by researchers at Saint Louis University has found that elephants play a key role in creating forests that store large amounts of atmospheric carbon and in maintaining the biodiversity of forests in Africa. Since elephants are endangered, their status represents a significant threat to an ecosystem that is very important to the Earth’s climate.

The African rainforest contains trees with both low carbon density (light wood) and high carbon density (heavy wood). High carbon density trees grow more slowly and can be crowded out by the faster growing low carbon density trees rising above them. Elephants affect the relative abundance of these trees by feeding more on the low carbon density trees which are more palatable and nutritious. This thinning of the forest allows the trees that sequester the most carbon to flourish.

Elephants are also excellent dispersers of the seeds of high carbon density trees. Essentially, elephants are the gardeners of the forest. They plant the forest with high carbon density trees and get rid of the weeds – in this case, the low carbon density trees. According to the study, if elephants were to become extinct, the African rainforest – the second largest on earth – would gradually lose between six and nine percent of its ability to capture atmospheric carbon.

Elephants have been hunted by humans for millennia. Gaining support for protecting them has mostly been driven by the argument that everybody loves elephants. Focusing on their role in maintaining forest diversity has not driven much more action. The hope is that the evidence of how important elephants are for climate mitigation will be taken seriously by policy makers to generate the support needed for improved elephant conservation.

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Can Elephants Save the Planet?

Photo, posted March 15, 2008, courtesy of Michelle Gadd/USFWS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Agriculture Turning Wild Plants Into Weeds | Earth Wise

February 7, 2023 By EarthWise Leave a Comment

We often hear about the importance of native plants in the environment and how invasive species can wreak havoc with ecosystems. But it turns out that human activities can change the characteristics of native species and create unexpected new problems.

Common waterhemp is plant native to North America that typically grows near lakes and streams. It never used to be any kind of problem, but in recent times it has become nearly impossible to eradicate from farms as a result of genetic adaptations triggered by modern agriculture.

A study led by researchers at the University of British Columbia looked at waterhemp samples from modern farms and neighboring wetlands and compared them with historical samples dating back as far as 1820 stored in various museums.

In recent times, mutations in genes related to drought tolerance, rapid growth, and resistance to herbicides have resulted in waterhemp that has become a pervasive weed on farms. These genetic shifts, scarcely ever seen in historical samples, have made the plant thrive among human agricultural activities and enable it to outcompete crops.

Genetic analysis of the plants showed that herbicide-resistant mutations that were mostly absent from historical samples stand out as factors that allow waterhemp to prosper in agricultural settings. There are some plants in natural habitats that have herbicide-resistant mutations, but in many cases, these mutations are actually harmful to the plants in the wild.

Understanding how plant adaptations occur on relatively short timescales is increasingly important as farming and climate change continue to drive rapid plant evolution.

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How intensive agriculture turned a wild plant into a pervasive weed

Photo, posted February 16, 2016, courtesy of Aqua Mechanical via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Benefits Of No-Till Farming | Earth Wise

October 5, 2021 By EarthWise Leave a Comment

No-till farming is not new. In fact, it was used as far back as 10,000 years ago. But during the 18th and 19th centuries, tilling became popular because it allowed farmers to plant seeds more efficiently.

Tilling (or ploughing) is the process of preparing the soil for the cultivation of seeds by overturning the soil. The practice works animal manure, weeds, and other surface residues deep into the soil. While this all sounds like a good thing, it’s not.

Tilling removes plant matter and loosens the soil, leaving the soil bare and vulnerable to erosion. Tilling also displaces the millions of microbes and insects that form healthy soil biology. The long-term use of tilling can turn healthy soils into lifeless growing mediums dependent on chemical inputs.

But no-till farming also tends to rely on chemical inputs like glyphosate for weed control. According to a new study recently published in Agronomy Journal, researchers at Penn State have found that farmers using no-till farming can reduce herbicide use and still maintain crop yields by implementing integrated weed-management methods.

The research team conducted a nine-year experiment using herbicide-reduction practices in a crop rotation, which included soybean, corn, alfalfa, and canola. Some of the practices used to reduce herbicide inputs included seeding small-grain companion crops with perennials, and plowing once in six years to terminate the perennial forage rather than killing it with an herbicide.

While there was more weed biomass in the reduced herbicide treatment, the researchers found that the added weed pressure did not substantially affect crop yields.

It is possible to make agriculture more environmentally-friendly and sustainable without sacrificing productivity.

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No-till production farmers can cut herbicide use, control weeds, protect profits

Photo, posted February 11, 2019, courtesy of the United Soybean Board via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Potential For Solar Canals In California | Earth Wise

April 29, 2021 By EarthWise Leave a Comment

California’s network of almost 4,000 miles of aqueducts is the world’s largest water conveyance system. It serves the state’s Central Valley which produces a quarter of America’s food. About 20% of the nation’s groundwater demand is pumped from Central Valley aquifers.

A recent study by the University of California Santa Cruz and UC Merced has determined that covering these aqueducts with solar panels could be an economically feasible way to advance both renewable energy and water conservation. California’s aqueducts might more properly be called canals because they are located at ground level.

The concept of solar canals has been gaining increasing interest around the world as the changing climate leads to more droughts in many regions. Placing solar panels above the canals can shade them to help prevent water loss through evaporation. In addition, some types of solar panels can work better situated over canals because the cooler environment improves their operation. In addition to the increased solar panel output and the water evaporation savings, shade from solar panels could help control the growth of aquatic weeds, which are a costly canal maintenance issue.

Spanning canals with solar panels can be accomplished either by using steel trusses or suspension cables, either of which is more expensive to build than ordinary ground-mounted solar panel supports. But the research study showed how the benefits of solar canals combine to outweigh the added costs for cable-supported installations.

Apart from the economic benefits of a solar canal system, producing solar energy in the canal system could eliminate the use of 15-20 diesel-powered irrigation pumps, helping to reduce air pollution in a region with some of the nation’s worst air quality.

Solar canals could be a real winner.

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New analysis shows potential for ‘solar canals’ in California

Photo, posted July 23, 2015, courtesy of Lance Cheung / USDA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Allergies | Earth Wise

March 23, 2021 By EarthWise Leave a Comment

According to a new study published in the Proceedings of the National Academy of Sciences, an addition to the many hardships that climate change is causing around the world is the fact that it is making allergy season worse.

Researchers have found that there is a strong link between planetary warming and pollen seasons. The combination of warming air and higher levels of carbon dioxide in the atmosphere has caused North American pollen seasons since 1990 to start some 20 days earlier, on average, and to have 21% more pollen.

The most pronounced effects were seen in Texas, the Midwest, and the Southeast. The effects were less obvious in the northern United States, including New England and the Great Lakes states. The greatest pollen increases came from trees, as opposed to grasses and weeds.

Allergies do not just trigger sniffles and sneezes; they have serious effects on public health in the form of asthma and other respiratory conditions. Studies have shown that students do less well in school during peak pollen season. Of special concern at the moment is that high-pollen periods have been associated with greater susceptibility to respiratory viruses. The U.S. has nearly 25 million people with asthma and 19 million adults reported hay fever in the past 12 months. Research suggests that the early onset of pollen season correlates with a higher risk of hospitalization for asthma.

There are far fewer pollen monitoring stations than those measuring particle pollutants and air quality. As the climate warms, we need to pay more attention to pollen as an airborne pollutant.

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Achoo! Climate Change Lengthening Pollen Season in U.S., Study Shows

Photo, posted May 18, 2012, courtesy of Forest Wander via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Not Enough Buzz For Bees | Earth Wise

February 11, 2021 By EarthWise Leave a Comment

The dramatic worldwide decline in bees and other pollinating insects represents a serious threat to the global food supply, but it isn’t really getting much attention in the mainstream news. Close to 75% of the world’s crops for human consumption depend, at least in part, on pollinators for sustained production, yield, and quality.

A new study by researchers at the University of Illinois Urbana-Champaign looked at nearly 25 million news items from six prominent sources, including The New York Times, The Washington Post, the Associated Press, as well as three overseas English-language news services. The study found “vanishingly low levels of attention to pollinator population topics”, even compared with what many people consider to be the limited coverage of climate change.

The study made use of the Global News Index, which is a unique database of millions of news items from thousands of global sources published over decades. It may be the largest academic study of the evolving nature of news coverage ever performed.

Even though the entomological community is highly focused on the impending pollinator crisis, the public is not paying much attention. It is not even indifference; it is just that people don’t even know about it.

The majority of studies on pollinator decline have been done in Europe and North America, which means we don’t even know how serious the problem is given that most insect biodiversity is in the tropics.

Public awareness is important because individuals can make a difference by their decisions about what flowers to plant in their gardens, which weeds to tolerate in their yards, and how to manage insect pests.

The loss of pollinators is a very serious problem, and it is not likely to get enough attention if people don’t know about it.

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Pollinators not getting the ‘buzz’ they need in news coverage

Photo, posted December 28, 2006, courtesy of Alpha via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Birdseed And Weeds | Earth Wise

April 16, 2020 By EarthWise Leave a Comment

More than 55 million adult Americans feed wild birds and along the way spend more than three billion dollars a year on bird food as well as nearly a billion on bird feeders, bird baths, bird houses and other bird feeding accessories. Feeding birds is a very popular hobby in both the United States and the United Kingdom.

Researchers at the University of Missouri in Columbia Missouri investigated the content of 98 commercially available bird feed mixes. They uncovered several significant things.

The various mixes contained seeds from 29 weed species and almost all of the mixes contained seeds for pigweed, which can be a significant threat to agriculture. One in ten of the mixes contained Palmer amaranth or waterhemp seeds that demonstrated a resistance to glyphosphate. Other common weed species found in many of the mixes were kochia, common ragweed, foxtail species, and wild buckweed.

The overall collection of seed mixes contained an average of 363 amaranthus seeds in each kilogram of bird feed. Based on this, it is possible that 105 million amaranthus seeds are transported in bird feed mixes each year.

According to the researchers, it is difficult to estimate the exact role that commercial bird seed plays in spreading troublesome weed species into new regions, but it is clear that the widespread use of these seed mixes is a contributing factor to the spread of weeds.

The researchers recommend careful weed management in crop fields designated for bird feed, as well as sieving during packaging to reduce weed seed contamination. They also noted that regulatory measures adopted in Europe to limit weed seed content in bird seed have proven to be effective.

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