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.
By Dana M Bergstrom, Euan Ritchie, Lesley Hughes and Michael Depledge
In 1992, 1,700 scientists warned that human beings and the natural world were "on a collision course." Seventeen years later, scientists described planetary boundaries within which humans and other life could have a "safe space to operate." These are environmental thresholds, such as the amount of carbon dioxide in the atmosphere and changes in land use.
The Good and Bad News<p><span>Ecosystems consist of living and non-living components, and their interactions. They work like a super-complex engine: when some components are removed or stop working, knock-on consequences can lead to system failure.</span></p><p>Our study is based on measured data and observations, not modeling or predictions for the future. Encouragingly, not all ecosystems we examined have collapsed across their entire range. We still have, for instance, some intact reefs on the Great Barrier Reef, especially in deeper waters. And northern Australia has some of the most intact and least-modified stretches of savanna woodlands on Earth.</p><p><span>Still, collapses are happening, including in regions critical for growing food. This includes the </span><a href="https://www.mdba.gov.au/importance-murray-darling-basin/where-basin" target="_blank" rel="noopener noreferrer">Murray-Darling Basin</a><span>, which covers around 14% of Australia's landmass. Its rivers and other freshwater systems support more than </span><a href="https://www.abs.gov.au/ausstats/[email protected]/latestproducts/94F2007584736094CA2574A50014B1B6?opendocument" target="_blank" rel="noopener noreferrer">30% of Australia's food</a><span> production.</span></p><p><span></span><span>The effects of floods, fires, heatwaves and storms do not stop at farm gates; they're felt equally in agricultural areas and natural ecosystems. We shouldn't forget how towns ran out of </span><a href="https://www.mdba.gov.au/issues-murray-darling-basin/drought#effects" target="_blank" rel="noopener noreferrer">drinking water</a><span> during the recent drought.</span></p><p><span></span><span>Drinking water is also at risk when ecosystems collapse in our water catchments. In Victoria, for example, the degradation of giant </span><a href="https://theconversation.com/logging-must-stop-in-melbournes-biggest-water-supply-catchment-106922" target="_blank" rel="noopener noreferrer">Mountain Ash forests</a><span> greatly reduces the amount of water flowing through the Thompson catchment, threatening nearly five million people's drinking water in Melbourne.</span></p><p>This is a dire <em data-redactor-tag="em">wake-up</em> call — not just a <em data-redactor-tag="em">warning</em>. Put bluntly, current changes across the continent, and their potential outcomes, pose an existential threat to our survival, and other life we share environments with.</p><p><span>In investigating patterns of collapse, we found most ecosystems experience multiple, concurrent pressures from both global climate change and regional human impacts (such as land clearing). Pressures are often </span><a href="https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2664.13427" target="_blank" rel="noopener noreferrer">additive and extreme</a><span>.</span></p><p>Take the last 11 years in Western Australia as an example.</p><p>In the summer of 2010 and 2011, a <a href="https://theconversation.com/marine-heatwaves-are-getting-hotter-lasting-longer-and-doing-more-damage-95637" target="_blank" rel="noopener noreferrer">heatwave</a> spanning more than 300,000 square kilometers ravaged both marine and land ecosystems. The extreme heat devastated forests and woodlands, kelp forests, seagrass meadows and coral reefs. This catastrophe was followed by two cyclones.</p><p>A record-breaking, marine heatwave in late 2019 dealt a further blow. And another marine heatwave is predicted for <a href="https://www.theguardian.com/environment/2020/dec/24/wa-coastline-facing-marine-heatwave-in-early-2021-csiro-predicts" target="_blank" rel="noopener noreferrer">this April</a>.</p>
What to Do About It?<p><span>Our brains trust comprises 38 experts from 21 universities, CSIRO and the federal Department of Agriculture Water and Environment. Beyond quantifying and reporting more doom and gloom, we asked the question: what can be done?</span></p><p>We devised a simple but tractable scheme called the 3As:</p><ul><li>Awareness of what is important</li><li>Anticipation of what is coming down the line</li><li>Action to stop the pressures or deal with impacts.</li></ul><p>In our paper, we identify positive actions to help protect or restore ecosystems. Many are already happening. In some cases, ecosystems might be better left to recover by themselves, such as coral after a cyclone.</p><p>In other cases, active human intervention will be required – for example, placing artificial nesting boxes for Carnaby's black cockatoos in areas where old trees have been <a href="https://www.environment.gov.au/biodiversity/threatened/publications/factsheet-carnabys-black-cockatoo-calyptorhynchus-latirostris" target="_blank" rel="noopener noreferrer">removed</a>.</p><p><span>"Future-ready" actions are also vital. This includes reinstating </span><a href="https://www.abc.net.au/gardening/factsheets/a-burning-question-fire/12395700" target="_blank" rel="noopener noreferrer">cultural burning practices</a><span>, which have </span><a href="https://theconversation.com/australia-you-have-unfinished-business-its-time-to-let-our-fire-people-care-for-this-land-135196" target="_blank" rel="noopener noreferrer">multiple values and benefits for Aboriginal communities</a><span> and can help minimize the risk and strength of bushfires.</span></p><p>It might also include replanting banks along the Murray River with species better suited to <a href="https://www.abc.net.au/gardening/factsheets/my-garden-path---matt-hansen/12322978" target="_blank" rel="noopener noreferrer">warmer conditions</a>.</p><p>Some actions may be small and localized, but have substantial positive benefits.</p><p>For example, billions of migrating Bogong moths, the main summer food for critically endangered mountain pygmy possums, have not arrived in their typical numbers in Australian alpine regions in recent years. This was further exacerbated by the <a href="https://theconversation.com/six-million-hectares-of-threatened-species-habitat-up-in-smoke-129438" target="_blank" rel="noopener noreferrer">2019-20</a> fires. Brilliantly, <a href="https://www.zoo.org.au/" target="_blank" rel="noopener noreferrer">Zoos Victoria</a> anticipated this pressure and developed supplementary food — <a href="https://theconversation.com/looks-like-an-anzac-biscuit-tastes-like-a-protein-bar-bogong-bikkies-help-mountain-pygmy-possums-after-fire-131045" target="_blank" rel="noopener noreferrer">Bogong bikkies</a>.</p><p><span>Other more challenging, global or large-scale actions must address the </span><a href="https://www.youtube.com/watch?v=iICpI9H0GkU&t=34s" target="_blank" rel="noopener noreferrer">root cause of environmental threats</a><span>, such as </span><a href="https://www.nature.com/articles/s41559-018-0504-8" target="_blank" rel="noopener noreferrer">human population growth and per-capita consumption</a><span> of environmental resources.</span><br></p><p>We must rapidly reduce greenhouse gas emissions to net-zero, remove or suppress invasive species such as <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/mam.12080" target="_blank" rel="noopener noreferrer">feral cats</a> and <a href="https://theconversation.com/the-buffel-kerfuffle-how-one-species-quietly-destroys-native-wildlife-and-cultural-sites-in-arid-australia-149456" target="_blank" rel="noopener noreferrer">buffel grass</a>, and stop widespread <a href="https://theconversation.com/to-reduce-fire-risk-and-meet-climate-targets-over-300-scientists-call-for-stronger-land-clearing-laws-113172" target="_blank" rel="noopener noreferrer">land clearing</a> and other forms of habitat destruction.</p>
Our Lives Depend On It<p>The multiple ecosystem collapses we have documented in Australia are a harbinger for <a href="https://www.iucn.org/news/protected-areas/202102/natures-future-our-future-world-speaks" target="_blank">environments globally</a>.</p><p>The simplicity of the 3As is to show people <em>can</em> do something positive, either at the local level of a landcare group, or at the level of government departments and conservation agencies.</p><p>Our lives and those of our <a href="https://theconversation.com/children-are-our-future-and-the-planets-heres-how-you-can-teach-them-to-take-care-of-it-113759" target="_blank">children</a>, as well as our <a href="https://theconversation.com/taking-care-of-business-the-private-sector-is-waking-up-to-natures-value-153786" target="_blank" rel="noopener noreferrer">economies</a>, societies and <a href="https://theconversation.com/to-address-the-ecological-crisis-aboriginal-peoples-must-be-restored-as-custodians-of-country-108594" target="_blank" rel="noopener noreferrer">cultures</a>, depend on it.</p><p>We simply cannot afford any further delay.</p><p><em><a rel="noopener noreferrer" href="https://theconversation.com/profiles/dana-m-bergstrom-1008495" target="_blank" style="">Dana M Bergstrom</a> is a principal research scientist at the University of Wollongong. <a rel="noopener noreferrer" href="https://theconversation.com/profiles/euan-ritchie-735" target="_blank" style="">Euan Ritchie</a> is a professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences at Deakin University. <a rel="noopener noreferrer" href="https://theconversation.com/profiles/lesley-hughes-5823" target="_blank">Lesley Hughes</a> is a professor at the Department of Biological Sciences at Macquarie University. <a rel="noopener noreferrer" href="https://theconversation.com/profiles/michael-depledge-114659" target="_blank">Michael Depledge</a> is a professor and chair, Environment and Human Health, at the University of Exeter. </em></p><p><em>Disclosure statements: Dana Bergstrom works for the Australian Antarctic Division and is a Visiting Fellow at the University of Wollongong. Her research including fieldwork on Macquarie Island and in Antarctica was supported by the Australian Antarctic Division.</em></p><p><em>Euan Ritchie receives funding from the Australian Research Council, The Australia and Pacific Science Foundation, Australian Geographic, Parks Victoria, Department of Environment, Land, Water and Planning, and the Bushfire and Natural Hazards CRC. Euan Ritchie is a Director (Media Working Group) of the Ecological Society of Australia, and a member of the Australian Mammal Society.</em></p><p><em>Lesley Hughes receives funding from the Australian Research Council. She is a Councillor with the Climate Council of Australia, a member of the Wentworth Group of Concerned Scientists and a Director of WWF-Australia.</em></p><p><em>Michael Depledge does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</em></p><p><em>Reposted with permission from <a href="https://theconversation.com/existential-threat-to-our-survival-see-the-19-australian-ecosystems-already-collapsing-154077" target="_blank" style="">The Conversation</a>. </em></p>
- Coral Reef Tipping Point: 'Near-Annual' Bleaching May Occur ... ›
- Scientists Warn Humanity in Denial of Looming 'Collapse of ... ›
EcoWatch Daily Newsletter
To save the planet, we must save the Amazon rainforest. To save the rainforest, we must save its indigenous peoples. And to do that, we must demarcate their land.
A new EarthxTV film special calls for the protection of the Amazon rainforest and the indigenous people that call it home. EarthxTV.org
- Meet the 'Women Warriors' Protecting the Amazon Forest - EcoWatch ›
- Indigenous Tribes Are Using Drones to Protect the Amazon ... ›
- Amazon Rainforest Will Collapse by 2064, New Study Predicts ... ›
- Deforestation in Amazon Skyrockets to 12-Year High Under Bolsonaro ›
- Amazon Rainforest on the Brink of Turning Into a Net Carbon Emitter ... ›
By Anke Rasper
"Today's interim report from the UNFCCC is a red alert for our planet," said UN Secretary General Antonio Guterres.
The report, released Friday, looks at the national climate efforts of 75 states that have already submitted their updated "nationally determined contributions," or NDCs. The countries included in the report are responsible for about 30% of the world's global greenhouse gas emissions.
- World Leaders Fall Short of Meeting Paris Agreement Goal - EcoWatch ›
- UN Climate Change Conference COP26 Delayed to November ... ›
- 5 Years After Paris: How Countries' Climate Policies Match up to ... ›
- Biden Win Puts World 'Within Striking Distance' of 1.5 C Paris Goal ... ›
- Biden Reaffirms Commitment to Rejoining Paris Agreement ... ›
India's New Delhi has been called the "world air pollution capital" for its high concentrations of particulate matter that make it harder for its residents to breathe and see. But one thing has puzzled scientists, according to The Guardian. Why does New Delhi see more blinding smogs than other polluted Asian cities, such as Beijing?
- This Indian Startup Turns Polluted Air Into Climate-Friendly Tiles ... ›
- How to Win the Fight Against Plastic - EcoWatch ›
In a historic move, the Delaware River Basin Commission (DRBC) voted Thursday to ban hydraulic fracking in the region. The ban was supported by all four basin states — New Jersey, Delaware, Pennsylvania and New York — putting a permanent end to hydraulic fracking for natural gas along the 13,539-square-mile basin, The Philadelphia Inquirer reported.
- Appalachian Fracking Boom Was a Jobs Bust, Finds New Report ... ›
- Long-Awaited EPA Study Says Fracking Pollutes Drinking Water ... ›
- Pennsylvania Fracking Water Contamination Much Higher Than ... ›