Mixed Forests Are Healthier, But Can They Survive Climate Change?
By Tim Radford
German researchers have confirmed once again that a good forest is a mixed forest, a natural one, with a diversity of species. The more diverse the forest, the better it becomes at doing what forests do.
Forests with a greater number of species grow at a faster rate, store more carbon, and are more resistant to pests and diseases, according to a six-nation study of European woodlands.
But this safety-in-species-numbers approach may not offer quite the protection against climate change and its consequences that such a finding should predict. A second study by European researchers suggests that when conditions become extremely wet, or extremely dry, diversity may not confer automatic resilience.
The message is that healthy, diverse, natural forest systems remain important buffers against climate change—but also that climate extremes could diminish the capacity of the forest to absorb carbon and limit global warming.
At the heart of both studies is a deeper concern about the response of the natural world to human-induced change, in the destruction of habitat, the loss of the plants, birds, insects, mammals, amphibians and reptiles that depend on habitat, and in the steady increase in atmospheric levels of greenhouse gases, as a consequence of profligate combustion of fossil fuels.
Repeated studies have confirmed that the world's forests are under threat. Repeated studies have confirmed that in overall rewards for humanity, undisturbed natural forests deliver a greater economic return. And repeated studies have confirmed that rising global temperatures offer a threat to plant diversity around the planet in general and to Europe in particular.
Researchers at the Centre for Integrative Biodiversity Research in Germany reported in the journal Ecology Letters that they selected plots of forest in Germany, Finland, Poland, Romania, Italy and Spain.
Within these plots the numbers of species varied: there might be one species, or five. The German plot, for example was home to beech, oak, Norway spruce, birch and hornbeam.
The scientists then measured 26 functions in these plots that could answer questions about nutrients, carbon cycles, growth and resilience and forest regeneration. Those stands of timber with more species grew faster and withstood pests and disease assault better than those with fewer.
"Our summers will be drier and longer as a result of climate change," said Christian Wirth, who directs the Cenre for Integrative Biodiversity Research and heads the department for systematic botany at Leipzig University. "We are therefore presuming that in future, it will be even more important to manage forests in a way that they have a high diversity of tree species."
But a study in the Journal of Ecology suggests that the answer may not be so simple.
Researchers led by Hans de Boeck from the University of Antwerp reported that they looked at a wide range of studies of what scientists call ecosystem stability and biodiversity during climate extremes—that is, unusual heat, drought or flooding.
The answer, they found, was mixed. A greater range of diversity in an ecosystem seemed to speed up recovery after an extreme climatic event, but if the event was extreme enough biodiversity alone might not offer much protection.
The relationship between diversity and resistance wasn't always obvious. Researchers, the scientists suggested, have more questions to resolve.
In the stilted language of sciencespeak, the researchers concluded that "there are numerous and non-trivial exceptions to the purported general rule that biodiversity increases stability. This raises the question of whether existing concepts of biodiversity-stability derived from the context of mild fluctuations are readily transposable to extreme events."
Reposted with permission from our media associate Climate News Network.
Yet another former Trump administration staffer has come out with an endorsement for former Vice President Joe Biden, this time in response to President Donald Trump's handling of the coronavirus pandemic.
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Every September for the past 11 years, non-profit the Climate Group has hosted Climate Week NYC, a chance for business, government, activist and community leaders to come together and discuss solutions to the climate crisis.
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By D. André Green II
One of nature's epic events is underway: Monarch butterflies' fall migration. Departing from all across the United States and Canada, the butterflies travel up to 2,500 miles to cluster at the same locations in Mexico or along the Pacific Coast where their great-grandparents spent the previous winter.
Millions of People Care About Monarchs<p>I will never forget the sights and sounds the first time I visited monarchs' overwintering sites in Mexico. Our guide pointed in the distance to what looked like hanging branches covered with dead leaves. But then I saw the leaves flash orange every so often, revealing what were actually thousands of tightly packed butterflies. The monarchs made their most striking sounds in the Sun, when they burst from the trees in massive fluttering plumes or landed on the ground in the tussle of mating.</p><p>Decades of educational outreach by teachers, researchers and hobbyists has cultivated a generation of monarch admirers who want to help preserve this phenomenon. This global network has helped restore not only monarchs' summer breeding habitat by planting milkweed, but also general pollinator habitat by planting nectaring flowers across North America.</p><p>Scientists have calculated that restoring the monarch population to a stable level of about 120 million butterflies will require <a href="https://doi.org/10.1111/icad.12198" target="_blank">planting 1.6 billion new milkweed stems</a>. And they need them fast. This is too large a target to achieve through grassroots efforts alone. A <a href="https://www.fws.gov/savethemonarch/CCAA.html" target="_blank" rel="noopener noreferrer">new plan</a>, announced in the spring of 2020, is designed to help fill the gap.</p>
Pros and Cons of Regulation<p>The top-down strategy for saving monarchs gained energy in 2014, when the U.S. Fish and Wildlife Service <a href="https://www.fws.gov/southeast/pdf/petition/monarch.pdf" target="_blank">proposed</a> listing them as threatened under the Endangered Species Act. A decision is expected in December 2020.</p><p>Listing a species as endangered or threatened <a href="https://www.fws.gov/endangered/esa-library/pdf/listing.pdf" target="_blank">triggers restrictions</a> on "taking" (hunting, collecting or killing), transporting or selling it, and on activities that negatively affect its habitat. Listing monarchs would impose restrictions on landowners in areas where monarchs are found, over vast swaths of land in the U.S.</p><p>In my opinion, this is not a reason to avoid a listing. However, a "threatened" listing might inadvertently threaten one of the best conservation tools that we have: public education.</p><p>It would severely restrict common practices, such as rearing monarchs in classrooms and back yards, as well as scientific research. Anyone who wants to take monarchs and milkweed for these purposes would have to apply for special permits. But these efforts have had a multigenerational educational impact, and they should be protected. Few public campaigns have been more successful at raising awareness of conservation issues.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="91165203d4ec0efc30e4632a00fdf57d"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/KilPRvjbMrA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The Rescue Attempt<p>To preempt the need for this kind of regulation, the U.S. Fish and Wildlife Service approved a <a href="https://www.fws.gov/savethemonarch/pdfs/Monarch%20CCAA-CCA%20Public%20Comment%20Documents/Monarch-Nationwide_CCAA-CCA_Draft.pdf" target="_blank">Nationwide Candidate Conservation Agreement for Monarch Butterflies</a>. Under this plan, "rights-of-way" landowners – energy and transportation companies and private owners – commit to restoring and creating millions of acres of pollinator habitat that have been decimated by land development and herbicide use in the past half-century.</p><p>The agreement was spearheaded by the <a href="http://rightofway.erc.uic.edu/" target="_blank">Rights-of-Way Habitat Working Group</a>, a collaboration between the University of Illinois Chicago's <a href="https://erc.uic.edu/" target="_blank" rel="noopener noreferrer">Energy Resources Center</a>, the Fish and Wildlife Service and over 40 organizations from the energy and transportation sectors. These sectors control "rights-of-way" corridors such as lands near power lines, oil pipelines, railroad tracks and interstates, all valuable to monarch habitat restoration.</p><p>Under the plan, partners voluntarily agree to commit a percentage of their land to host protected monarch habitat. In exchange, general operations on their land that might directly harm monarchs or destroy milkweed will not be subject to the enhanced regulation of the Endangered Species Act – protection that would last for 25 years if monarchs are listed as threatened. The agreement is expected to create up to 2.3 million acres of new protected habitat, which ideally would avoid the need for a "threatened" listing.</p>
A Model for Collaboration<p>This agreement could be one of the few specific interventions that is big enough to allow researchers to quantify its impact on the size of the monarch population. Even if the agreement produces only 20% of its 2.3 million acre goal, this would still yield nearly half a million acres of new protected habitat. This would provide a powerful test of the role of declining breeding and nectaring habitat compared to other challenges to monarchs, such as climate change or pollution.</p><p>Scientists hope that data from this agreement will be made publicly available, like projects in the <a href="https://www.fws.gov/savethemonarch/MCD.html" target="_blank">Monarch Conservation Database</a>, which has tracked smaller on-the-ground conservation efforts since 2014. With this information we can continue to develop powerful new models with better accuracy for determining how different habitat factors, such as the number of milkweed stems or nectaring flowers on a landscape scale, affect the monarch population.</p><p>North America's monarch butterfly migration is one of the most awe-inspiring feats in the natural world. If this rescue plan succeeds, it could become a model for bridging different interests to achieve a common conservation goal.</p>
The annual Ig Nobel prizes were awarded Thursday by the science humor magazine Annals of Improbable Research for scientific experiments that seem somewhat absurd, but are also thought-provoking. This was the 30th year the awards have been presented, but the first time they were not presented at Harvard University. Instead, they were delivered in a 75-minute pre-recorded ceremony.