8 in 10 lizards could be at risk due to deforestation

In Colorado, people flock to the Rocky Mountains when the summer heat gets unbearable. Animals seek shelter too when temperatures become extreme, and forests serve as critical sanctuaries for small tree-dwelling animals like lizards.

In a new study published March 5 in the journal Nature Climate Change, scientists from the University of Colorado Boulder and Tel Aviv University in Israel revealed that deforestation combined with climate change could negatively impact 84% of North America's lizards by the end of the century. Nearly one in five could face population decline.

Unlike mammals that can maintain their body temperatures in a variety of ways -- sweating when it gets too hot and relying on warm fur when it gets too cold -- cold-blooded animals like lizards have limited strategies to thermoregulate. Tree-climbing lizards move around tree trunks to bask in the sun for warmth. When the ground gets too hot, they climb higher or move into the shade.

"What's really interesting about lizards is that they just need to be able to move a short distance around the tree trunk to get to a very different climate and habitat environment," said Keith Musselman, an assistant professor in the Department of Geography and CU Boulder's Institute of Arctic and Alpine Research. "These microhabitats are particularly important when we think about how we modify our natural environment and make conservation decisions."

Using computer simulations, the team showed that global warming can actually benefit lizards living in colder regions or at higher latitudes in North America. Warmer weather increases the animals' activity time, meaning they have more time to look for food or mates during the day. However, deforestation would largely reverse these positive effects by reducing opportunities for shade in hotter climates that help them cool down.

The team simulated lizard models for different climate regions across North America. They found that tree loss could decrease lizards' activity time by an average of 34% by the end of the century. Without trees, the animals would have to hide under rocks or in caves to avoid overheating. The impact would be especially prominent for species that already live in warmer regions, where future summers will become too warm for activity on the ground.

The team estimated that deforestation would accelerate population declines for 18% of lizards in North America.

"Our work provides new insights into the mechanisms by which deforestation may cause population declines in the face of climate change," said Ofir Levy, a zoologist and Musselman's collaborator at Tel Aviv University. "The decline in lizards can lead to a cascading effect as they are an important part of almost every ecological system."

Despite international pledges to halt deforestation, tree clearing continues to happen globally. From 2001 to 2022, about 459 million hectares, or 12%, of global tree cover disappeared.

"Deforestation is a worldwide problem, and our conclusions can help decision-makers on other continents in designing conservation and habitat restoration programs that consider climate change," said Omer Zlotnick, the paper's first author and a Ph.D. student at Tel Aviv University.

Lizard populations are already at risk because of climate change. In one study, scientists estimated that 54% of lizard populations in Mexico would go extinct by 2080 because of their inability to adapt to the rapidly warming planet.

Deforestation would further exacerbate the threat by taking away these animals' refuges.

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Deforestation in the tropics linked to a reduction in rainfall

Deforestation is resulting in reduced rainfall across large parts of the tropics, according to new research.

People living in tropical forest communities have often complained that the climate gets hotter and drier once trees are cleared but until now, scientists have not been able to identify a clear link between the loss of tree cover and a decline in rainfall.

A research team at the University of Leeds combined satellite data of deforestation and rainfall to show that the loss of tree cover in the tropics over the last 14 years was associated with reductions in rainfall.

They estimate that by the end of the century, if the rate of deforestation in the Congo was to continue, rainfall in the region could be reduced by between 8% and 12%, with a major impact on biodiversity, farming and could threaten the viability of the Congo forests, which are among the world's largest stores of carbon.

Callum Smith, a doctoral researcher in the School of Earth and Environment at Leeds and the lead author in the study, said the investigation provides "compelling evidence" to protect forests from uncontrolled clearing.

He added: "Tropical forests play a critical role in the hydrological cycle through helping to maintain local and regional rainfall patterns. The reduction in rainfall caused by tropical deforestation will impact people living nearby through increased water scarcity and depressed crop yields.

"Tropical forests themselves rely on moisture to survive and remaining areas of forest will be impacted by a drier climate."

The research paper -- Tropical deforestation causes large reductions in observed precipitation -- is published today (Wed, March 1st) in the scientific journal Nature.

The researchers looked at the impact of forest loss in three areas of the tropics -- the Amazon, Congo and Southeast Asia -- which have all experienced rapid land-use changes. The study involved analysis of satellite observations from 2003 to 2017, to identify locations where forests had been cleared. Rainfall data in these areas, also measured by satellites, was compared to rainfall from nearby locations where forests had not been lost.

Forest loss linked to rainfall loss

The study revealed that tropical forest loss caused reductions in rainfall throughout the year, including in the dry season when any further drying will have the biggest ramifications on plant and animal ecosystems. The greatest absolute decline in precipitation was seen in the wet season with up to a 0.6 mm a month reduction in rainfall for every percentage point loss of forest cover.

Writing in the paper, the researchers warn that climate change will lead to increased drought and that will be exacerbated by continued deforestation.

Link between forest cover and rainfall

It is believed the loss of tree cover disrupts the process where moisture from leaves -- through a mechanism called evapotranspiration -- is returned to the atmosphere where it eventually forms rain clouds.

As well as impacting natural ecosystems, a reduction in rainfall would be detrimental to agriculture and hydropower plants. That would have a strong impact both on the healthy functioning of the forests and on local communities.

The research team say, on average, crop yields declined by 0.5% for every 1% reduction in rainfall.

Tropical forests sustain rainfall

Professor Dominick Spracklen, from the School of Earth and Environment at Leeds who supervised the project, said: "Local people living near deforested regions often report a hotter and drier climate after the forests are cleared. But until now this effect had not been seen in rainfall observations.

"The study shows the critical importance of tropical forests in sustaining rainfall. Although there have been efforts to halt deforestation, the loss of forest cover in the tropics has continued. There needs to be renewed efforts to stop forests being lost and to regenerate lost and degraded areas."

The scientists warn that a decline in rainfall has a negative impact on biodiversity, increases the risk of forest fires and reduces carbon sequestration, where nature removes carbon from the atmosphere and stores it.

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Companies' 'deforestation-free' supply chain pledges have barely impacted forest clearance in the Amazon, researchers say

More companies must make and implement zero-deforestation supply chain commitments in order to significantly reduce deforestation and protect diverse ecosystems, say researchers.

Corporate pledges not to buy soybeans produced on land deforested after 2006 have reduced tree clearance in the Brazilian Amazon by just 1.6% between 2006 and 2015.

This equates to a protected area of 2,300 km2 in the Amazon rainforest: barely the size of Oxfordshire in the UK.

The findings, made by tracing traders' soy supplies back to their source, are published today in the journal Environmental Research Letters. The work involved a team from the University of Cambridge, Boston University, ETH Zurich and New York University.

The researchers also discovered that in the Cerrado, Brazil's tropical savannah, zero-deforestation commitments have not been adopted effectively -- leaving over 50% of soy-suitable forests and their biodiversity without protection.

Brazil has the largest remaining tropical forests on the planet, but these are being rapidly cleared to rear cattle and grow crops including soybean. Demand for soy is surging around the world, and an estimated 4,800 km2 of rainforest is cleared each year to grow soybeans.

The majority of soy is consumed indirectly by humans: soybean is widely used as feed for factory-farmed chickens, pigs, fish and cattle. It also accounts for around 27% of global vegetable oil production, and as a complete protein source it often forms a key part of vegetarian and vegan diets.

By 2021, at least 94 companies had adopted zero-deforestation commitments -- pledging to eliminate deforestation from their supply chains. But the study revealed that many of these commitments are not put into practice.

And the researchers say that adoption of zero-deforestation commitments is lagging among small and medium sized food companies.

"Zero-deforestation pledges are a great first step, but they need to be implemented to have an effect on forests -- and right now it's mainly the bigger companies that have the resources to do this," said Professor Rachael Garrett, Moran Professor of Conservation and Development at the University of Cambridge Conservation Research Institute, a joint senior author of the report.

She added: "If soybean traders actually implemented their global commitments for zero-deforestation production, current levels of forest clearance in Brazil could be reduced by around 40 percent."

Deforestation is the second largest contributor to global greenhouse gas emissions after fossil fuel use. It also causes the loss of diverse animal and plant life, threatens the livelihoods of indigenous groups, and increases inequality and conflict.

The researchers say that the supply chains of other food products including cattle, oil palm and cocoa supply chains are more complex than soy, making them even more difficult to monitor.

"If supply chain policies intend to contribute to the task of tackling deforestation in Brazil, it's crucial to expand zero-deforestation supply chain policies beyond soy," said Garrett, who is also Professor of Environmental Policy at ETH Zurich.

A 'soy moratorium' was the first voluntary zero-deforestation commitment in the tropics -- by signing it, companies agreed not to buy soybeans produced on land deforested after 2006. But while the commitment was implemented in the Brazilian Amazon, most Brazilian soy is produced in the Cerrado -- which is rich in biodiversity.

The researchers say their findings suggest private sector efforts are not enough to halt deforestation: supportive political leadership is also vital to conservation efforts.

"Supply chain governance should not be a substitute for state-led forest policies, which are critical to enable zero deforestation monitoring and enforcement, have better potential to cover different crops, land users, and regions," said Garrett.

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Amazon deforestation threatens newly discovered fish species in Brazil

Smithsonian's National Museum of Natural History researcher Murilo Pastana and his colleagues have discovered and described two new species of Amazonian fish -- one with striking red-orange fins and the other so small it is technically considered a miniature fish species -- in a paper published today, May 16, in the Zoological Journal of the Linnean Society.

Both species inhabit waters located at the bleeding edge of human encroachment into the Amazon rainforest roughly 25 miles north of the Brazilian city of Apuí. Pastana and his co-authors, Willian Ohara with the Federal University of Rondônia and Priscila Camelier with the Federal University of Bahia, said that ongoing deforestation in the region places these roughly inch-long fish, part of a group known colloquially as the South American darters, in imminent danger of extinction. In particular, the more colorful of the two species, Poecilocharax callipterus, is at risk because its known range is limited to a single stream comprising roughly 1.5 square miles of habitat.

"It was exciting to find new species," Pastana said. "But in the field, we saw the forest on fire, logging trucks carrying out huge trees, and cleared patches turned into cattle pasture. This made us feel a lot of urgency to document these species and publish this paper as quickly as possible."

As a Brazilian-born scientist, Pastana is passionate about preserving the country's biological heritage, and his hope is that naming and describing these species might motivate the Brazilian government to protect and conserve these newly discovered, endangered fishes.

The small subfamily to which these previously unknown fish species belong is also highly desirable in the aquarium hobbyist market. Pastana, whose work is supported by the Smithsonian's Sara E. and Bruce B. Collette Postdoctoral Fellowship in Systematic Ichthyology, said that the exotic aquarium fish trade could pose yet another threat to these two new species even as scientists are first formally identifying them and learning of their existence.

The expeditions that uncovered these new freshwater species took place between 2015 and 2016. Pastana said the broad goal of these forays into the Brazilian Amazon was to search out the still unknown biological treasures of the many waterways in the Madeira River Basin, the richest river basin in the world in terms of fish biodiversity according to a 2019 estimate.

"We went to sample places that have never been visited by scientists," Pastana said. "This area is really important because this is one of the frontiers where deforestation is moving north -- the border between new cities and native forest."

The Apuí region where these scientific surveys took place sits at number two on a recent list of Brazilian municipalities with the highest deforestation rates. Ironically, the same roads that facilitate the region's accelerating loss of habitat also facilitated access to formerly unreachable streams, ponds and tributaries for Pastana and his colleagues.

So, in 2015 and 2016 Pastana and others camped along a road called AM-174 and collected fish using nets, traps and other methods. All the specimens were photographed, cataloged and preserved for further study back at the Museum of Zoology, University of São Paulo.

One of these specimens has vivid red-orange fins and a distinctive dark spot just in front of its tail. This fish stood out immediately as a new species, Pastana said. The fish, which has now been named P. callipterus, inhabits the margins of what scientists call a black water stream, so named because its waters are stained the color of coffee by tannins leached from fallen leaves. Males of the species have even more intense coloration and sport dorsal fins that can exceed half their body length, which averages just over an inch. Despite targeted efforts to seek out this species in the surrounding area on the 2016 return trip, Pastana and his colleagues were only able to find P. callipterus in the stream in which it was first discovered.

Researchers encountered the second new species documented on these field expeditions among tangles of tree roots protruding from the banks of muddy watered streams -- distinct from the relatively translucent, if darkly stained, black water streams. Given the scientific name P. rhizophilus for its love (phil) of roots (rhiz), this species is an amber yellow with males possessing dark streaks in their dorsal and anal fins. But perhaps the most distinctive quality of this new species is that it is so small that scientists consider it to be miniature, a designation given to any fish that is less than about an inch long when mature, Pastana said. He added that lab study revealed that in these three-quarter-inch-long fish, parts of the skeleton that are typically bone are instead made of cartilage.

Genetic investigations confirmed the evolutionary relationship of these two new closely related species and their relatives, bringing the total number of species in their small sub-family (Crenuchinae) to five. This is the first addition of a new species to the group in 57 years.

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Number of Earth's tree species estimated to be 14% higher than currently known, with some 9,200 species yet to be discovered

A new study involving more than 100 scientists from across the globe and the largest forest database yet assembled estimates that there are about 73,000 tree species on Earth, including about 9,200 species yet to be discovered.

The global estimate is about 14% higher than the current number of known tree species. Most of the undiscovered species are likely to be rare, with very low populations and limited spatial distribution, the study shows.

That makes the undiscovered species especially vulnerable to human-caused disruptions such as deforestation and climate change, according to the study authors, who say the new findings will help prioritize forest conservation efforts.

"These results highlight the vulnerability of global forest biodiversity to anthropogenic changes, particularly land use and climate, because the survival of rare taxa is disproportionately threatened by these pressures," said University of Michigan forest ecologist Peter Reich, one of two senior authors of a paper scheduled for publication Jan. 31 in Proceedings of the National Academy of Sciences.

"By establishing a quantitative benchmark, this study could contribute to tree and forest conservation efforts and the future discovery of new trees and associated species in certain parts of the world," said Reich, director of the Institute for Global Change Biology at U-M's School for Environment and Sustainability.

For the study, the researchers combined tree abundance and occurrence data from two global datasets -- one from the Global Forest Biodiversity Initiative and the other from TREECHANGE -- that use ground-sourced forest-plot data. The combined databases yielded a total of 64,100 documented tree species worldwide, a total similar to a previous study that found about 60,000 tree species on the planet.

"We combined individual datasets into one massive global dataset of tree-level data," said the study's other senior author, Jingjing Liang of Purdue University, coordinator of the Global Forest Biodiversity Initiative.

"Each set comes from someone going out to a forest stand and measuring every single tree -- collecting information about the tree species, sizes and other characteristics. Counting the number of tree species worldwide is like a puzzle with pieces spread all over the world."

After combining the datasets, the researchers used novel statistical methods to estimate the total number of unique tree species at biome, continental and global scales -- including species yet to be discovered and described by scientists. A biome is a major ecological community type, such as a tropical rainforest, a boreal forest or a savanna.

Their conservative estimate of the total number of tree species on Earth is 73,274, which means there are likely about 9,200 tree species yet to be discovered, according to the researchers, who say their new study uses a vastly more extensive dataset and more advanced statistical methods than previous attempts to estimate the planet's tree diversity. The researchers used modern developments of techniques first devised by mathematician Alan Turing during World War II to crack Nazi code, Reich said.

Roughly 40% of the undiscovered tree species -- more than on any other continent -- are likely to be in South America, which is mentioned repeatedly in the study as being of special significance for global tree diversity.

South America is also the continent with the highest estimated number of rare tree species (about 8,200) and the highest estimated percentage (49%) of continentally endemic tree species -- meaning species found only on that continent.

Hot spots of undiscovered South American tree species likely include the tropical and subtropical moist forests of the Amazon basin, as well as Andean forests at elevations between 1,000 meters (about 3,300 feet) and 3,500 meters (about 11,480 feet).

"Beyond the 27,000 known tree species in South America, there might be as many as another 4,000 species yet to be discovered there. Most of them could be endemic and located in diversity hot spots of the Amazon basin and the Andes-Amazon interface," said Reich, who was recruited by U-M's Biosciences Initiative and joined the faculty last fall from the University of Minnesota, where he maintains a dual appointment.

"This makes forest conservation of paramount priority in South America, especially considering the current tropical forest crisis from anthropogenic impacts such as deforestation, fires and climate change," he said.

Worldwide, roughly half to two-thirds of all already known tree species occur in tropical and subtropical moist forests, which are both species-rich and poorly studied by scientists. Tropical and subtropical dry forests likely hold high numbers of undiscovered tree species, as well.

"Extensive knowledge of tree richness and diversity is key to preserving the stability and functioning of ecosystems," said study lead author Roberto Cazzolla Gatti of the University of Bologna in Italy.

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Satellite map of human pressure on land provides insight on sustainable development

 The coronavirus pandemic has led researchers to switch gears or temporarily abandon projects due to health protocols or not being able to travel. But for Patrick Keys and Elizabeth Barnes, husband and wife scientists at Colorado State University, this past year led to a productive research collaboration.

They teamed up with Neil Carter, assistant professor at the University of Michigan, on a paper published in Environmental Research Letters that outlines a satellite-based map of human pressure on lands around the world.

Keys, lead author and a research scientist in CSU's School of Global Environmental Sustainability, said the team used machine learning to produce the map, which reveals where abrupt changes in the landscape have taken place around the world. The map shows a near-present snapshot of effects from deforestation, mining, expanding road networks, urbanization and increasing agriculture.

"The map we've developed can help people understand important challenges in biodiversity conservation and sustainability in general," said Keys.

This type of a map could be used to monitor progress for the United Nations Sustainable Development Goal 15 (SDG15), "Life on Land," which aims to foster sustainable development while conserving biodiversity.

Eight algorithms to encompass data from around the world

Barnes, an associate professor in CSU's Department of Atmospheric Science, did the heavy lifting on the data side of the project.

While staggering parenting duties with Keys, she wrote code like never before, working with trillions of data points and training up to eight separate algorithms to cover different parts of the world. She then merged the algorithms to provide a seamless classification for the whole planet.

At first, the two researchers had to learn to speak the other's work language.

"Pat initially had an idea for this research, and I said, 'Machine learning doesn't work that way,'" said Barnes.

She then sketched out the components with him: The input is something we want to be able to see from space, like a satellite image; and the output is some measure of what humans are doing on Earth. The middle part of the equation was machine learning.

Keys said what Barnes designed is a convolutional neural network, which is commonly used for interpreting images. It's similar to how Facebook works when the site suggests tagging friends in a photo.

"It's like our eyes and our brains," he said.

In developing the algorithm, they used existing data that classified human impacts on the planet, factors like roads and buildings, and grazing lands for livestock and deforestation. Then, the convolutional neural network learned how to accurately interpret satellite imagery, based on this existing data.

From an analysis of one country, to the world

The researchers started with Indonesia, a country that has experienced rapid change over the last 20 years. By the end of the summer, after they were confident about what they identified in Indonesia using machine learning, Keys suggested that they look at the entire globe.

"I remember telling him it's not possible," said Barnes. "He knows whenever I say that, I will go back and try and make it work. A week later, we had the whole globe figured out."

Barnes said using machine learning is not fool-proof, and it requires some follow-up to ensure that data are accurate.

"Machine learning will always provide an answer, whether it's garbage or not," she explained. "Our job as scientists is to determine if it is useful."

Keys spent many nights on Google Earth reviewing over 2,000 places on the globe in the year 2000 and then compared those sites with 2019. He noted changes and confirmed the data with Barnes.

The research team also did a deeper dive into three countries -- Guyana, Morocco and Gambia -to better understand what they found.

In the future, when new satellite data is available, Keys said the team can quickly generate a new map.

"We can plug that data into this now-trained neural network and generate a new map," he said. "If we do that every year, we'll have this sequential data that shows how human pressure on the landscape is changing."

Keys said the research project helped lift his spirits over the last year.

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