Halve the Farmland, Save Nature, Feed the World
By Tim Radford
Forget about organic farming: get the best out of the best cropland, return the rest to nature and still feed the world. It could work, say researchers.
Once again, scientists have demonstrated that humans could restore roughly half the planet as a natural home for all the other wild things, while at the same time feeding a growing population and limiting climate change.
That doesn't mean it will happen, or could be made to happen easily. But it does yet again address one of the enduring challenges of population growth and the potentially devastating loss of the biodiversity upon which all individual species – humans more than most – depend to survive.
The answer? Simply to farm more efficiently and more intensively, to maximize the yield from those tracts of land most suitable for crops, and let nature reclaim the no-longer so productive hectares.
Even more effective would be to release as much land as possible in those regions that ecologists and biologists like to call "biodiversity hotspots," among them the forests where concentrations of species are at their peak.
European researchers argue, in a study in the journal Nature Sustainability, that as less land was cultivated, but more intensively, the greenhouse gas emissions from farming would be reduced: so too would water use.
"The main questions we wanted to address were how much cropland could be spared if attainable crop yields were achieved globally and crops were grown where they are most productive," said Christian Folberth, a scientist with the International Institute for Applied Systems Analysis (IIASA) in Austria, who led the study.
"In addition, we wanted to determine what the implications would be for other factors related to the agricultural sector, including fertilizer and irrigation water requirements, greenhouse gas emissions, carbon sequestration potential, and wildlife habitat for threatened species."
The problem is enormous, and enormously complex. Cropland farming alone – forget about methane from cattle and sheep – accounts for 5% of all greenhouse gas emissions from human activity. Worldwide, about 70% of all the freshwater taken from rivers and aquifers goes into irrigation.
Global heating driven by fossil fuel investment continues to increase, and this in turn threatens to diminish harvest yields across a wide range of crops, along with the nutritive value of the staples themselves.
Nature under threat
At the same time, both climate change driven by global warming and the expansion of the cities and the surrounding farmlands continue to amplify the threat to natural habitats and the millions of species – many yet to be identified and named by science – that depend upon them.
And this in turn poses a threat to human economies and even human life: almost every resource – antibiotic medicines and drugs, food, waste disposal, fabrics, building materials and even fresh air and water – evolved in undisturbed ecosystems long before Homo sapiens arrived, and the services each element provides depend ultimately on the survival of those ecosystems.
So the challenge is to restore and return to nature around half the land humans already use, while at the same time feeding what could be an additional 2bn people, while reducing greenhouse gas emissions but still sustaining development in the poorest nations.
The scientists looked at the data for 16 major crop species around the world to calculate that at least in theory – with careful use of the right crops on the most suitable soils, and with high fertilizer use – about half of the present cropland now cultivated could still deliver the present output.
That is, the land humans occupy is not being managed efficiently. If it were, the other half could be returned to wilderness, and conserved as natural forest, grassland or wetland.
If humans then thought about how best to slow biodiversity loss, they would do almost as well by abandoning farmland in those places where there was the greatest concentration of wild things – tropical rain forests, estuary floodplains and mangrove swamps, for instance. And just returning 20% of farmland to nature everywhere else would still reduce human farmland use by 40%.
In return, fertilizer use would remain about the same, but greenhouse gas emissions and water use would fall, while more land would become free to sequester atmospheric carbon.
There would be costs – nitrogen pollution would go up in some places, and many rural farmers would become even poorer – so more thinking needs to be done. The point the European researchers want to make is that, in principle, it should be possible to feed people, abandon farmland to the natural world and reduce emissions all at the same time.
"It shows that cropland expansion is not inevitable and there is significant potential for improving present land use efficiency," said Michael Obersteiner, another author, now at the Environmental Change Institute at Oxford.
"If the right policies are implemented, measures such as improved production technologies can be just as effective as demand-side measures like dietary changes. However, in all cases, such a process would need to be steered by policies to avoid unwanted outcomes."
This story originally appeared in Climate News Network and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.
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By Katherine Kornei
Clear-cutting a forest is relatively easy—just pick a tree and start chopping. But there are benefits to more sophisticated forest management. One technique—which involves repeatedly harvesting smaller trees every 30 or so years but leaving an upper story of larger trees for longer periods (60, 90, or 120 years)—ensures a steady supply of both firewood and construction timber.
A Pattern in the Rings<p>The <a href="https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/coppice-standards-0" target="_blank">coppice-with-standards</a> management practice produces a two-story forest, said <a href="https://www.researchgate.net/profile/Bernhard_Muigg" target="_blank">Bernhard Muigg</a>, a dendrochronologist at the University of Freiburg in Germany. "You have an upper story of single trees that are allowed to grow for several understory generations."</p><p>That arrangement imprints a characteristic tree ring pattern in a forest's upper story trees (the "standards"): thick rings indicative of heavy growth, which show up at regular intervals as the surrounding smaller trees are cut down. "The trees are growing faster," said Muigg. "You can really see it with your naked eye."</p><p>Muigg and his collaborators characterized that <a href="https://ltrr.arizona.edu/about/treerings" target="_blank">dendrochronological pattern</a> in 161 oak trees growing in central Germany, one of the few remaining sites in Europe with actively managed coppice-with-standards forests. They found up to nine cycles of heavy growth in the trees, the oldest of which was planted in 1761. The researchers then turned to a historical data set — more than 2,000 oak <a href="https://eos.org/articles/podcast-discovering-europes-history-through-its-timbers" target="_blank" rel="noopener noreferrer">timbers from buildings and archaeological sites</a> in Germany and France dating from between 300 and 2015 — to look for a similar pattern.</p>
A Gap of 500 Years<p>The team found wood with the characteristic coppice-with-standards tree ring pattern dating to as early as the 6th century. That was a surprise, Muigg and his colleagues concluded, because the first mention of this forest management practice in historical documents occurred only roughly 500 years later, in the 13th century.</p><p>It's probable that forest management practices were not well documented prior to the High Middle Ages (1000–1250), the researchers suggested. "Forests are mainly mentioned in the context of royal hunting interests or donations," said Muigg. Dendrochronological studies are particularly important because they can reveal information not captured by a sparse historical record, he added.</p><p>These results were <a href="https://www.nature.com/articles/s41598-020-78933-8" target="_blank">published in December in <em>Scientific Reports</em></a>.</p><p>"It's nice to see the longevity and the history of coppice-with-standards," said <a href="https://www.teagasc.ie/contact/staff-directory/s/ian-short/" target="_blank">Ian Short</a>, a forestry researcher at Teagasc, the Agriculture and Food Development Authority in Ireland, not involved in the research. This technique is valuable because it promotes conservation and habitat biodiversity, Short said. "In the next 10 or 20 years, I think we'll see more coppice-with-standards coming back into production."</p><p>In the future, Muigg and his collaborators hope to analyze a larger sample of historic timbers to trace how the coppice-with-standards practice spread throughout Europe. It will be interesting to understand where this technique originated and how it propagated, said Muigg, and there are plenty of old pieces of wood waiting to be analyzed. "There [are] tons of dendrochronological data."</p><p><em><a href="mailto:firstname.lastname@example.org" target="_blank" rel="noopener noreferrer">Katherine Kornei</a> is a freelance science journalist covering Earth and space science. Her bylines frequently appear in Eos, Science, and The New York Times. Katherine holds a Ph.D. in astronomy from the University of California, Los Angeles.</em></p><p><em>This story originally appeared in <a href="https://eos.org/articles/tree-rings-reveal-how-ancient-forests-were-managed" target="_blank">Eos</a></em> <em>and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.</em></p>
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