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Cell structure linked to longevity of slow-growing ponderosa pines

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Slow-growing ponderosa pines may have a better chance of surviving longer than fast-growing ones, especially as climate change increases the frequency and intensity of drought, according to new research from the University of Montana.

Researchers found that ponderosa longevity might hinge on the shape of microscopic valve-like structures between the cells that transport water through the tree.

The study, led by UM alumna Beth Roskilly and Professor Anna Sala, was published in the Proceedings of the National Academy of Sciences. The researchers sampled growth rates of ponderosa pine trees of varying ages at two remote sites in Idaho. They also studied structural traits of the trees’ xylem – vascular tissue that transports water and minerals through the wood and provides structural support.

Their findings reveal that some young trees grow quickly while others grow slowly. But old ponderosa pine trees – those older than 350 years – are slow growers compared to younger trees, and these individual trees have always been slow growing, even when they were young.

In contrast to predictions, slow-growing trees, whether old or young, did not produce denser, tougher wood, which might have made the trees more resistant to disease or decay. Instead, a key difference between fast and slow growers resides in a microscopic valve-like structure between the cells that transport water in the wood, called the pit membrane. The unique shape of this valve in slow-growing trees provides greater safety against drought, but it slows down water transport, limiting growth rate.

“Ponderosa pines, like people, cannot have it all,” said Roskilly, the paper’s lead author. “Drought resistance contributes to longevity but also to slow growth. In other words, there is a fundamental tradeoff based on xylem structure. Our study suggests that trees with fast growth become large quickly, which can be beneficial for young trees competing for resources, but they are more vulnerable to drought and can die at earlier ages. On the other hand, trees that grow slowly are more drought resistant, which enhances longevity.”

Roskilly earned her UM master’s degree in organismal biology, ecology and evolution in 2018, and the study is a result of her degree work in UM’s College of Humanities and Sciences.

“Ancient trees are special for many reasons,” said Sala, a professor in UM’s Division of Biological Sciences and an adjunct professor in the W.A. Franke College of Forestry and Conservation. “They are beautiful, they make the highest quality musical instruments, they help maintain diversity, and they store atmospheric carbon in wood for a long time. But the results of this research also suggest they are special because forest managers cannot make just any ponderosa pine tree live for centuries no matter how hard they try. For ponderosa pines to become centennials, their wood must possess this unique structure.”

Other co-authors in the study include UM alumnus Eric Keeling, a professor at the State University of New York; UM alumna Sharon Hood, a research ecologist with the U.S. Forest Service; and Arnaud Giuggiola, a former visiting master’s student from the University of Bordeaux. This project built on dissertation work by Keeling and began as an undergraduate research project started by Roskilly.

Read the paper: PNAS

Article source: University of Montana

Image: Beth Roskilly

Assessing the greenhouse gas impact of forest management activities in EU countries

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On 18 June 2019, the Commission published its assessment of Member States’ draft plans to implement the EU’s Energy Union objectives, in particular the agreed EU 2030 energy and climate targets, as well as technical recommendations on Member States’ National Forestry Accounting Plans.

These plans contain a proposed “Forest Reference Levels”, which act as a baseline for future greenhouse gas emissions and removals from managed forest land.

The JRC played a key role in the development of this concept, which allows assessing the greenhouse gas impact of human action in the forestry sector.

Measuring the impact of human action in the forestry sector

The EU has set a target for reducing its anthropogenic greenhouse gas (GHG) emissions by at least 40% by 2030 relative to 1990.

As explained by Giacomo Grassi, the JRC’s expert on measuring the climate impact of forest management, “it is rather straightforward to measure the impacts of human activities on emissions from, for instance, the energy sector: all emissions are anthropogenic and any reduction of emissions can be claimed as anthropogenic. But in the forestry sector this becomes more challenging”.

Forest trees absorb CO2 through photosynthesis, and therefore mitigate climate change. In the EU, for example, forests offset nearly 10% of total EU GHG emissions.

However, to give the right policy incentives for enhancing our carbon sinks, we need to identify how much of this absorption is due to recent forest management decisions.

“If you plant a tree, continues Giacomo, this is clearly a result of recent human action. However, the CO2 absorption in the majority of existing EU forests is largely affected by natural factors or by management choices done a long time ago, e.g. when your grand-grandfather planted a tree”.

Measuring how much of the current CO2 absorption by forests is due to ongoing human activities has therefore long been a demanding task.

Science-based carbon accounting system for forest management

A JRC-led group of forest experts has developed a new science-based approach to assess the greenhouse gas impact of human action in the forestry sector.

This approach is based on country-specific projected baselines which will be used to measure the GHG impact of future forest activities.

“In other words, says Giacomo, each country calculates how much CO2 would be absorbed by its forests without changing the current management. This sets the baseline, called Forest Reference Level”.

This approach ensures greater environmental integrity and comparability of mitigation efforts across sectors of the economy.

At the same time, it allows to reflect the country-specific forest dynamics, for example if a forest on average is getting older.

Integrating the land-use, land-use change and forestry (LULUCF) sector in the EU climate strategy

This approach was included in the EU Regulation from 2018 incorporating the forest sector in the EU 2030 climate targets.

As required by this Regulation, the EU Member States propose their Forest Reference Levels for the period 2021-2025.

An expert group composed of Member States representatives, technical specialists, NGOs and research organisations was formed to undertake a technical assessment of the plans and the proposed forest reference level.

The JRC played a very active role in facilitating this technical assessment.

The Commission has now issued technical recommendations reflecting the conclusions of the assessment process.

These technical recommendations will form the basis for the revision of Member States’ forest reference levels, which are to be submitted by 31 December 2019.

The Commission will then adopt delegated acts containing the final forest reference levels for the period 2021 and 2025 by 31 October 2020.

Article source: European Commission, Joint Research Centre (JRC)

Image: pixel2013/Pixabay

Wheat myth comes a cropper

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The myth that modern wheat varieties are more heavily reliant on pesticides and fertilisers than older varieties has been debunked by new research.

The University of Queensland’s Dr Kai Voss-Fels said modern wheat varieties have out-performed older varieties in side-by-side field trials under both optimum and harsh growing conditions.

“There is a view that intensive selection and breeding, which has produced the high-yielding wheat cultivars used in modern cropping, has also made them less resilient and more dependent on chemicals to thrive,” Dr Voss-Fels said.

“However, the data published today unequivocally shows that modern wheat out-performs older varieties, even under conditions of reduced amounts of fertilisers, fungicides and water.

“We also found that genetic diversity within the relatively narrow modern wheat gene pool is rich enough to potentially generate a further 23 per cent increase in yields.”

The researchers compared 200 wheat varieties, essential to agriculture in Western Europe over the past 50 years, under contrasting input levels of mineral fertilisers and plant protection chemicals.

Dr Voss-Fels said the findings might surprise some farmers and environmentalists.

“Quite a few people will be taken aback by just how tough modern wheat varieties proved to be, even in harsh growing conditions, such as drought, and using less chemical inputs.”

Dr Voss-Fels and Professor Ben Hayes at the Queensland Alliance for Agriculture and Food Innovation (QAFFI) developed a method to match the performance differences with the different varieties’ genetic make-up.

“This genetic information allows us to take the discovery to the next level,” Dr Voss-Fels said.

“We want to develop breeding strategies to bring together favourable alleles in new cultivars in the shortest possible time.”

“We are using artificial intelligence (AI) algorithms to predict the optimal crosses needed to bring together the most favourable segments as fast as possible.”

Global yields of the world’s most important food crop have been reduced by droughts in recent years.

Dr Voss-Fels said with more climate risk anticipated, the hardiness of modern wheat varieties was an issue of global significance.

“Increased breeding efforts are needed to enhance the resilience of wheat varieties to challenging environmental conditions.”

Dr Voss-Fels said the study’s findings could also have important implications for raising the productivity of organic cropping systems.

Professor Rod Snowdon of the Justus-Liebig-University Gießen (JLU) and collaborators from seven other German universities led the research.

Read the paper: Nature Plants

Article source: University of Queensland

Image: University of Queensland

Ancient DNA from Roman and medieval grape seeds reveal ancestry of wine making

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A grape variety, still used in wine production in France today, can be traced back 900 years to just one ancestral plant, scientists have discovered.

With the help of an extensive genetic database of modern grapevines, researchers were able to test and compare 28 archaeological seeds from French sites dating back to the Iron Age, Roman era, and medieval period.

Utilising similar ancient DNA methods used in tracing human ancestors, a team of researchers from the UK, Denmark, France, Spain, and Germany, drew genetic connections between seeds from different archaeological sites, as well as links to modern-day grape varieties.

It has long been suspected that some grape varieties grown today, particularly well-known types like Pinot Noir, have an exact genetic match with plants grown 2,000 years ago or more, but until now there has been no way of genetically testing an uninterrupted genetic lineage of that age.

Dr Nathan Wales, from the University of York‘s Department of Archaeology, said: “From our sample of grape seeds we found 18 distinct genetic signatures, including one set of genetically identical seeds from two Roman sites separated by more than 600km, and dating back 2,000 years ago.

“These genetic links, which included a ‘sister’ relationship with varieties grown in the Alpine regions today, demonstrate winemakers’ proficiencies across history in managing their vineyards with modern techniques, such as asexual reproduction through taking plant cuttings.”

One archaeological grape seed excavated from a medieval site in Orléans in central France was genetically identical to Savagnin Blanc. This means the variety has grown for at least 900 years as cuttings from just one ancestral plant.

This variety (not to be confused with Sauvignon Blanc), is thought to have been popular for a number of centuries, but is not as commonly consumed as a wine today outside of its local region.

The grape can still be found growing in the Jura region of France, where it is used to produce expensive bottles of Vin Jaune, as well as in parts of Central Europe, where it often goes by the name Traminer.

Although this grape is not so well known today, 900 years of a genetically identical plant suggests that this wine was special – special enough for grape-growers to stick with it across centuries of changing political regimes and agricultural advancements.

Advanced knowledge

Dr Jazmín Ramos-Madrigal, a postdoctoral researcher from the University of Copenhagen, said: “We suspect the majority of these archaeological seeds come from domesticated berries that were potentially used for winemaking based on their strong genetic links to wine grapevines.

“Berries from varieties used for wine are small, thick-skinned, full of seeds, and packed with sugar and other compounds such as acids, phenols, and aromas – great for making wine but not quite as good for eating straight from the vine. These ancient seeds did not have a strong genetic link to modern table grapes.

“Based on writings by the Roman author and naturalist, Pliny the Elder, and others, we know the Romans had advanced knowledge of winemaking and designated specific names to different grape varieties, but it has so far been impossible to link their Latin names to modern varieties.

“Now we have the opportunity to use genetics to know exactly what the Romans were growing in their vineyards.”

Roman seeds

Of the Roman seeds, the researchers could not find an identical genetic match with modern-day seeds, but they did find a very close relationships with two important grape families used to produce high quality wine.

These include the Syrah-Mondeuse Blanche family – Syrah is one of the most planted grapes in the world today – and the Mondeuse Blanche, which produces a high quality AOC (protected regional product) wine in Savoy, as well as the Pinot-Savagnin family – Pinot Noir being the “king of wine grapes”.

Further back in time

Dr Wales said: “It is rather unconventional to trace an uninterrupted genetic lineage for hundreds of years into the past. Instead of exploring broad patterns in genetic ancestry, as in most ancient DNA projects, we had to think like forensics scientists and find a perfect match in the database.

“Large databases of genetic data from modern crops and optimized palaeogenomic methods have vastly improved our ability to analyse the history of this and other important fruits.

“For the wine industry today, these results could shed new light on the value of some grape varieties; even if we don’t see them in popular use in wines today, they were once highly valued by past wine lovers and so are perhaps worth a closer look.”

The researchers now hope to find more archaeological evidence that could send them further back in time and reveal more grape wine varieties.

Read the paper: Nature Plants

Article source: University of York

Image: PIRO4D / Pixabay

Superweed resists another class of herbicides

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We’ve all heard about bacteria that are becoming resistant to multiple types of antibiotics. These are the so-called superbugs perplexing and panicking medical science. The plant analogue may just be waterhemp, a broadleaf weed common to corn and soybean fields across the Midwest. With resistance to multiple common herbicides, waterhemp is getting much harder to kill.

In a new study from the University of Illinois, scientists document waterhemp’s resistance to yet another class of herbicides, known as Group 15s. The study provides the first documentation of a non-grass plant to be resistant to Group 15 herbicides.

There are many herbicides on the market, but they all fall into one of 16 classes describing their mode of action (MOA), or specific target in the plant that the chemical attacks. Because of various regulations and biological realities, a smaller number of herbicide MOAs can be used on any given crop and the suite of weeds that goes along with it. Historically, about nine have been useful for waterhemp – and now the weed appears to be resistant to at least seven.

“In some areas, we’re one or two MOAs away from completely losing chemical control of waterhemp and other multiple-herbicide-resistant weeds,” says Adam Davis, head of the Department of Crop Sciences at Illinois and co-author on the study. “And there are no new herbicide MOAs coming out. There haven’t been for 30 years.”

Illinois weed scientist and co-author Aaron Hager adds, “We don’t want to panic people, but farmers need to be aware this is real. It continues on with the challenges we’ve warned people about for years.”

The research team tested the effectiveness of soil-applied Group 15 herbicides in a Champaign County population already resistant to five MOAs. They applied eight Group 15 formulations in the field at their label rates, and chose three – non-encapsulated acetochlor (Harness), S-metolachlor (Dual Magnum), and pyroxasulfone (Zidua) – for a rate-titration experiment in which the herbicides were applied at one-half, one, two, and four times the label rate.

The eight Group 15 products varied in their effectiveness, with encapsulated acetochlor (Warrant), S-metolachlor, metolachlor (Stalwart), and dimethenamid-P (Outlook) performing the worst. These products provided less than 25% control 28 days after application and less than 6% control 14 days later.

Of the rate-titration experiment, Hager says, “We found we could apply significantly higher than the labeled dose and still see resistance.” For example, S-metolachlor provided only 10% control at the standard label rate, 20% at 2x the label rate, and 45% at 4x the label rate.

Hager says farmers might not notice the poor performance of these soil-applied pre-emergence herbicides because waterhemp germinates continuously throughout the season. When a weed pops up mid-season, it’s hard to tell exactly when it emerged and whether it was exposed to residual soil-applied herbicides.

“If you think about how you use these products, rarely do they last the entire year. They’re very dependent on environmental conditions to work effectively. It could be too wet or too dry. Generally speaking, you have some weed escape. But many farmers would chalk it up to these weather issues. If you’re not thinking about it, you could very easily overlook resistance,” Hager says.

To confirm results from the field, the team performed a dose response test in the greenhouse. In that test, four waterhemp populations – three with resistance to multiple herbicides and one that is sensitive to all herbicides – were dosed with increasing levels of S-metolachlor, acetochlor, dimethenamid-P, and pyroxasulfone. Populations from Champaign County and McLean County survived higher levels of the Group 15 herbicides than the other populations.

Hager suspects the plants are breaking the chemicals down before they cause damage, a trick known as metabolic resistance. All organisms can turn on cellular defenses against toxins, but it is rather worrisome when weeds and other undesirable pests use their biology against human interventions.

“As we get into the era of metabolic resistance, our predictability is virtually zero. We have no idea what these populations are resistant to until we get them under controlled conditions,” Hager says. “It’s just another example of how we need a more integrated system, rather than relying on chemistry only. We can still use the chemistry, but have to do something in addition.

“We want farmers to understand that we have to rethink how we manage waterhemp long term.”

Read the paper: Weed Science

Article source: University of Illinois

Image: Aaron Hager with waterhemp. Photo by L. Brian Stauffer

Can a Hands-on Model Help Forest Stakeholders Fight Tree Disease?

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When a new, more aggressive strain of the pathogen that causes sudden oak death turned up in Oregon, scientists and stakeholders banded together to try to protect susceptible trees and the region’s valuable timber industry.

Sudden oak death is a serious threat. Since 1994, the disease has killed millions of trees in California and Oregon. If the disease spreads from an isolated outbreak in Curry County, Oregon, to neighboring Coos County, the impact could be severe: a 15% reduction in timber harvest, loss of 1,200 jobs and about $58 million in lost wages, according to an Oregon Department of Forestry report.

Researchers with North Carolina State University’s Center for Geospatial Analytics reached out to help in Oregon, offering Tangible Landscape, an interactive model that allows people of all skill levels to control complex simulation models with their hands and collaboratively explore scenarios of management decisions.

While predictive models can provide useful forecasts about where the pathogen may go, they can be tough to work with, requiring coding or technical software experience, says Devon Gaydos, lead author of an article in Philosophical Transactions of the Royal Society B: Biological Sciences and an NC State doctoral student.

“The Tangible Landscape system makes it a lot easier because people can interact with the model by touch instead of through the code or the computer,” Gaydos says. “People can add objects to a 3D model of the landscape to represent different types of management, and then with the click of a button we see how that action may affect the disease’s spread within a few moments.”

The model also allows participants to factor in budgets for disease management to try out different approaches to stop its spread, both on a large and small scale, Gaydos says.

“You can think of our disease spread model like a weather forecast: Knowing what the weather may look like this afternoon can help you decide if you want to bring an umbrella to work,” she explains. “Similarly, knowing how the pathogen may spread over the next year can help people gather resources, figure out which areas to target for surveillance or management, and request funding.”

Researchers took a participatory modeling approach because the disease could affect many stakeholders in Oregon – private landowners, timber producers, U.S. Forest Service managers, tribal groups that consider tanoak trees sacred, and thousands of local residents, including those employed in the timber industry. They began by working with a dozen local and regional experts, in the spirit of learning from each other.

“The idea of co-creating models with stakeholders is that by involving the people who are most affected, you’re going to get better data as a scientist because they have a lot of information about local dynamics and on-the-ground management that you may not know,” Gaydos says.

“It’s all about working together as partners to frame questions and problems, improve models and decide how to use those results for sustainable solutions,” adds co-author Ross Meentemeyer, NC State Forestry and Environmental Resources professor and director of the Center for Geospatial Analytics.

In this case, the team found out that some of the data used in the model needed to be more accurate at a fine scale – a problem participants could help with. In addition, the model needed to show the impact of decisions at more frequent intervals to capture the complexity of field operations.

The team also learned that collective action is paramount. Meentemeyer notes that “just a few uncooperative landowners ‘opting out’ of management could allow the pathogen to escape quarantine and the put the region at huge economic risk.”

After making adjustments, researchers plan to use an updated version of Tangible Landscape with a larger group of stakeholders in Oregon, as well as pursuing new research.

“More and more stakeholders are becoming interested in using the model, and the Oregon Department of Forestry wants to use it in an economic analysis of the situation and to test different management scenarios for the future,” Gaydos says.

“We are excited to collaborate with more teams and apply our modeling approach to forecast and control emerging infectious diseases of other plant, animal and human populations,” Meentemeyer says.

The article, “Forecasting and control of emerging infectious forest disease through participatory modelling,” appears in Philosophical Transactions of the Royal Society B: Biological Sciences. Co-authors include Anna Petrasova of NC State’s Center for Geospatial Analytics, Richard C. Cobb of California Polytechnic State University and Meentemeyer.

Read the paper: Philosophical Transactions of the Royal Society B: Biological Sciences

Article source: North Carolina State University

Image: Danny Norlander, Oregon Department of Forestry

Study reports breakthrough to measure plant improvements to help farmers boost production

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An international team is using advanced tools to develop crops that give farmers more options for sustainably producing more food on less land. To do this, thousands of plant prototypes must be carefully analyzed to figure out which genetic tweaks work best. In a special issue of the journal Remote Sensing of Environment, scientists have shown a new technology can more quickly scan an entire field of plants to capture improvements in their natural capacity to harvest energy from the sun.

“The method we developed allows us to measure improvements we have engineered in a plant’s photosynthesis machinery in about ten seconds, compared to the traditional method that takes up 30 minutes,” Katherine Meacham-Hensold, a postdoctoral researcher at the University of Illinois, who led this work for a research project called Realizing Increased Photosynthetic Efficiency (RIPE). “That’s a major advance because it allows our team to analyze an enormous amount of genetic material to efficiently pinpoint traits that could greatly improve crop performance.”

RIPE, which is led by Illinois, is engineering crops to be more productive by improving photosynthesis, the natural process all plants use to convert sunlight into energy and yield. RIPE is supported by the Bill & Melinda Gates Foundation, the Foundation for Food and Agriculture Research (FFAR), and the U.K. Government’s Department for International Development (DFID).

The traditional method for assessing photosynthesis analyzes the exchange of gases through the leaf; it provides a huge amount of information, but it takes 30 minutes to measure each leaf. A faster, or “higher-throughput” method, called spectral analysis, analyzes the light that is reflected back from leaves to predict photosynthetic capacity in as little as 10 seconds.

“The question we set out to answer is: can we apply spectral techniques to predict photosynthetic capacity when we have genetically altered the photosynthetic machinery,” said RIPE research leader Carl Bernacchi, a scientist with the U.S. Department of Agriculture, Agricultural Research Service, who is based at Illinois’ Carl R. Woese Institute for Genomic Biology. “Before this study, we didn’t know if changing the plant’s photosynthetic pathways would change the signal that is detected by spectral measurements.”

Although they can prove this method can be used to screen crops that have been engineered to improve photosynthesis, researchers have not uncovered what spectral analysis measures exactly. “Spectral analysis requires custom-built models to translate spectral data into measurements of photosynthetic capacity that must be recreated each year,” Meacham said. “Our next challenge is to figure out what we are measuring so that we can build predictive models that can be used year after year to compare results over time.”

“While there are still hurdles ahead, spectral analysis is a game-changing technique that can be used to assess a variety of photosynthetic improvements to single out the changes that are most likely to substantially, and sustainably, increase crop yields,” said RIPE executive committee member Christine Raines, a professor of plant molecular physiology at the University of Essex, whose engineered crops were analyzed with the technique. “These tools can help us speed up our efforts to develop high-yielding crops for farmers working to help feed the world.”

Read the paper: Remote Sensing of Environment

Article source: RIPE

Image: Beau Barber/University of Illinois

How plants are working hard for the planet

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As the planet warms, plants are working to slow the effect of human-caused climate change – and research published in Trends in Plant Science has assessed how plants are responding to increasing carbon dioxide (CO2).

“We know that terrestrial plants are currently absorbing more CO2 than is released into the atmosphere through the combination of fire, decomposition, plant respiration, and land-use change,” lead researcher Lucas Cernusak said.

“This is commonly known as the land carbon sink, and we know it’s currently slowing the rate at which atmospheric CO2 is increasing. What we don’t know is how strong that response is, and how long we can count on it. This research is a first step towards answering those questions.”

Associate Professor Cernusak, a terrestrial ecologist at James Cook University in Cairns, Australia, worked with colleagues from CSIRO Oceans and Atmosphere in Canberra and the French National Institute for Agricultural Research (INRA) to measure the strength of the terrestrial biosphere’s response to increasing CO2.

They focussed on photosynthesis – the process in which plants capture energy from the sun and use it to synthesize carbohydrates from CO2 and water – and examined terrestrial gross primary productivity (GPP), a measure of global photosynthesis.

Their modelling and analysis revealed that, since the beginning of the industrial era, photosynthesis has increased in nearly constant proportion to the rise in atmospheric CO2.

“We expected the two would corelate, since CO2 stimulates photosynthesis, but given the complexity of plant and environmental interactions we were impressed by how closely they have kept pace,” Associate Professor Cernusak said.

“We can say that plants are working hard –the response is at the highest end of the expected range.”

The researchers used a combination of existing analyses and new modelling, alongside laboratory studies, to examine how increased CO2 affects photosynthesis, from individual leaves up to a global scale.

“This is an important step forward in the long and complex task of gauging how terrestrial vegetation will respond to climate change in the longer term,” Associate Professor Cernusak said.

While increased CO2 has allowed an increase in photosynthesis and global leaf area, the researchers warn that further climate change – with increasing frequency of events such as heat waves, droughts and storms – has the potential to significantly stress terrestrial vegetation and decrease production.

“It’s also important to remember that global change will manifest differently in different regions,” Associate Professor Cernusak said.

“Our observations and modelling analyses suggest that in high latitude ecosystems it’s global warming that is driving the increase in leaf area and growing-season length.

“That’s quite different from the tropics, where our study indicates that CO2 fertilisation is driving the growth in photosynthesis, while climbing temperatures can create significant stress for some plant species.”

The researchers’ focus is now on the future.

“Looking back over time has answered one of the questions we started out with. We’re seeing a robust response from terrestrial ecosystems, or the land carbon sink, to increasing CO2.” Dr Cernusak said.

“The next step is to use what we’ve learnt, to develop ways to better predict how terrestrial ecosystems will interact with future changes in the global carbon cycle. That would help us answer that second question: how long can we count on plants to slow the rate at which atmospheric CO2 is increasing?”

Read the paper: Trends in Plant Science

Article source: James Cook University

Image: James Cook University

A global map to understand changing forests

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An international collaboration of hundreds of scientists – led in part by the Forest Advanced Computing and Artificial Intelligence (FACAI) Laboratory in Purdue’s Department of Forestry and Natural Resources – has developed the world’s first global map of tree symbioses. The map is key to understanding how forests are changing and the role climate plays in these shifts.

The findings, reported today in the journal Nature, come from the Global Forest Biodiversity Initiative (GFBI), a consortium of forest scientists and practitioners of which the FACAI Lab is a key hub and global center. Jingjing Liang, a Purdue University assistant professor of quantitative forest ecology, is co-supervisor of the FACAI Lab, coordinator and co-founder of the GFBI and co-lead author of the paper. Mo Zhou, a Purdue assistant professor of forest economics and management, is a senior author of the paper, co-supervisor of the FACAI Lab and lead economist of the GFBI.

Purdue’s FACAI Lab employs artificial intelligence and machine learning to study global, regional and local forest resource management and biodiversity conservation. For this research, FACAI compiled species abundance data from 55 million tree records in 1.2 million forest sample plots spanning 110 countries. The organization of the data was integral to developing the global map.

“The map and underlying global forest inventory database will serve as the foundation for research on the environmental impacts of forest changes, biological conservation and forest management,” Liang said.

The map identifies the types of mycorrhizal fungi associated with trees in a particular forest. These fungi attach to tree roots, extending a tree’s ability to reach water and nutrients while the tree provides carbon necessary for the fungi’s survival. The two most common types of mycorrhizae are arbuscular, which grow inside the tissues of tree roots and are associated with tree species such as maple, ash and yellow poplar, and ectomycorrhizal, which live on the outside of roots and are associated with tree species such as pine, oak, hickory and beech.

Those associations are important because the mycorrhizae affects the trees’ ability to access nutrients, sequester carbon and withstand the effects of climate change.

“Managing forests for climate change mitigation and sustainable development, therefore, should go well beyond managing only trees,” Zhou said.

The authors found that climate is the most significant factor affecting the distribution of mycorrhizae. A warming climate is reducing the abundance of ectomycorrhizal tree species by as much as 10 percent. That change is altering forests’ ecological and economic footprints, especially along the boreal-temperate ecotone, the border areas between colder and warmer forest. Losses to ectomycorrhizal species have implications for climate change since these fungi increase the amount of carbon stored in soil.

“Knowing the species composition in the forested area across the world is an important start,” Liang said. “There are many fundamental and socioeconomic questions we can answer now with GFBI data and cutting-edge machine learning techniques.”

The FACAI lab is currently developing collaborations to explore questions about ecology and economics, including self-learning forest models, innovative approaches to biodiversity valuation, locating unknown forest resources and space exploration.

The work aligns with Purdue’s Giant Leaps celebration, acknowledging the university’s global advancements made in health, space, artificial intelligence and sustainability as part of Purdue’s 150th anniversary. Those are the four themes of the yearlong celebration’s Ideas Festival, designed to showcase Purdue as an intellectual center solving real-world issues.

Brian S. Steidinger, a postdoctoral research fellow at Stanford University, and Thomas Ward Crowther, an assistant professor at ETH Zurich, are co-lead authors of the Nature paper with Liang. Sergio de Miguel, an assistant profession and principal investigator of the GFBI Hub at University of Lleida, Spain, and Xiuhai Zhao and Chunyu Zhang, professors at Beijing Forestry University, are among the senior collaborators of this paper.

Read the paper: Nature

Article source: Purdue

Image: Leonhard Steinacker

Amount of carbon stored in forests reduced as climate warms

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Accelerated tree growth caused by a warming climate does not necessarily translate into enhanced carbon storage, an international study suggests.

The team, led by the University of Cambridge, found that as temperatures increase, trees grow faster, but they also tend to die younger. When these fast-growing trees die, the carbon they store is returned to the carbon cycle.

The results, reported in the journal Nature Communications, have implications for global carbon cycle dynamics. As the Earth’s climate continues to warm, tree growth will continue to accelerate, but the length of time that trees store carbon, the so-called carbon residence time, will diminish.

During photosynthesis, trees and other plants absorb carbon dioxide from the atmosphere and use it to build new cells. Long-lived trees, such as pines from high elevations and other conifers found across the high-northern latitude boreal forests, can store carbon for many centuries.

“As the planet warms, it causes plants to grow faster, so the thinking is that planting more trees will lead to more carbon getting removed from the atmosphere,” said Professor Ulf Büntgen from Cambridge’s Department of Geography, the study’s lead author. “But that’s only half of the story. The other half is one that hasn’t been considered: that these fast-growing trees are holding carbon for shorter periods of time.”

Büntgen uses the information contained in tree rings to study past climate conditions. Tree rings are as distinctive as fingerprints: the width, density and anatomy of each annual ring contains information about what the climate was like during that particular year. By taking core samples from living trees and disc samples of dead trees, researchers are able to reconstruct how the Earth’s climate system behaved in the past and understand how ecosystems were, and are, responding to temperature variation.

For the current study, Büntgen and his collaborators from Germany, Spain, Switzerland and Russia, sampled more than 1100 living and dead mountain pines from the Spanish Pyrenees and 660 Siberian larch samples from the Russian Altai: both high-elevation forest sites that have been undisturbed for thousands of years. Using these samples, the researchers were able to reconstruct the total lifespan and juvenile growth rates of trees that were growing during both industrial and pre-industrial climate conditions.

The researchers found that harsh, cold conditions cause tree growth to slow, but they also make trees stronger, so that they can live to a great age. Conversely, trees growing faster during their first 25 years die much sooner than their slow-growing relatives. This negative relationship remained statistically significant for samples from both living and dead trees in both regions.

The idea of a carbon residence time was first hypothesised by co-author Christian Körner, Emeritus Professor at the University of Basel, but this is the first time that it has been confirmed by data.

The relationship between growth rate and lifespan is analogous to the relationship between heart rate and lifespan seen in the animal kingdom: animals with quicker heart rates tend to grow faster but have shorter lives on average.

“We wanted to test the ‘live fast, die young’ hypothesis, and we’ve found that for trees in cold climates, it appears to be true,” said Büntgen. “We’re challenging some long-held assumptions in this area, which have implications for large-scale carbon cycle dynamics.”

Read the paper: Nature Communications

Article source: University of Cambridge

Image: Ulf Buntgen

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