The ecology of crop pests

Ecological theory provides insights on pesticide use in agriculture

UNIVERSITY OF CALIFORNIA - SANTA BARBARA

Research News

 

As agriculture in the United States evolves, it's becoming more intensive and less complex. That means larger fields, more cropland and less crop diversity with fewer crops in rotation.

Ecological theory generally holds that diversity promotes stability in biological systems. Ashley Larsen, an assistant professor at UC Santa Barbara's Bren School of Environmental Science & Management, was curious how these tenets translate to agricultural landscapes, particularly with respect to crop pests.

Larsen and her colleague Frederik Noack, at the University of British Columbia, analyzed 13 years of data from Kern County, California -- which consistently tops lists of the nation's most valuable agricultural counties -- and discovered that less diverse croplands led to greater variability in pesticide use as well as to higher peak pesticide application. Their findings appear in the journal Nature Sustainability.

The idea that greater diversity stabilizes an ecosystem emerged around the 1940s, relatively early in the development of ecology as a field. The theory has encountered some skepticism throughout the years, and there's recently been a resurgence of interest in investigating this relationship.

Kern County provided a fantastic opportunity for the two researchers to study the phenomenon; in this case, how changes in crop and landscape diversity affect populations of crop pests.

"The U.S. has seen a shift toward larger agricultural enterprises," said Larsen. "So instead of small family farms we now have much bigger agricultural conglomerates." That has accompanied the trend of increasing field size and decreasing crop diversity. She suspects these all relate back to farmers taking advantage of the economy of scale.

Although Kern keeps extensive agricultural records, no one tracks the populations of pests, per se. This meant the researchers had to use a proxy: insecticide use. Only later did they appreciate how much this decision expanded the implications of their findings.

"Once you introduce insecticides into the study, then it's not just about diversity and stability in this ecological theory," Larsen said. "Now it has implications for environmental impacts and food security."

Larsen and Noack scoured the county records from 2005 through 2017 focusing on factors such as field size, as well as the amount and diversity of croplands. What they saw seemed to sync with their predictions. "We find increasing cropland in the landscape and larger fields generally increase the level and variability of pesticides, while crop diversity has the opposite effect," the authors wrote.

As field size increases, the area gets larger more quickly than the perimeter. This means that smaller fields have proportionally larger perimeters. And a larger perimeter may mean more spillover from nearby predators like birds, spiders and ladybugs that eat agricultural pests.

Smaller fields also create more peripheral habitat for predators and competitors that can keep pest populations under control. And since the center of a smaller field is closer to the edge, the benefits of peripheral land in reducing pests extends proportionally farther into the small fields.

Landscapes with diverse crops and land covers also correlated with reduced pesticide variability and overall use. Different crops in close proximity foster a variety of different pests. Though this may sound bad, it actually means that no single species will be able to multiply unimpeded.

"If agriculture is very simplified, there's little stopping a big outbreak of one type of pest," Larsen said. "If you're a pest in a monoculture, and that's your host crop, you have almost unlimited food resources."

Larsen and Noack's findings immediately suggest strategies for increasing food production while minimizing the impact of pesticides on human health and the environment. The study could not only help farmers make more informed decisions about field size and crop diversity, but also guide policy with the aim of decreasing insecticide use.

The Department of Agriculture's Farm Service Agency oversees several conservation-related programs addressing a number of different issues, including habitat preservation. Larsen suggests that tailoring these efforts to the nuances of different crop types could provide even greater benefits.

What's more, these voluntary programs currently focus on efforts by individual farmers. "Based on our results, we need to think, ideally, at more of a landscape scale," Larsen said.

It's difficult to untangle confounding factors in the relationship between land use and insecticide use. For instance, farmers put a lot of thought into how they plant their crops, potentially planting more valuable crops in larger fields or less diverse areas, Larsen explained. At the same time, farmers invest more in pest control, including chemical pesticides, for these high value crops, making it hard to tease apart the effect of landscape characteristics from these difficult-to-observe decisions.

The authors addressed these concerns using a combination of techniques borrowed from the economics literature in an attempt to establish a more causal understanding of the relationship between landscape characteristics and insecticide use.

California produces a diverse array of high-valued crops, from grapes and berries to almonds and citrus. This contrasts with regions like the Midwest and its amber waves of grain. Fields of cereals, like corn and wheat, can extend across vast swaths of the American heartland in virtual monocultures. What's more, these crops aren't nearly as valuable on a per-acre basis.

All these factors influence the risks associated with pests and the economics of pesticide application. "So it's hard to say whether these results would translate well to areas with very low value cropland because the incentives to really scout your pests might be much lower," Larsen said.

She has continued to investigate the effects of land use on agricultural production at both regional and national scales. In a recent paper published in the journal Landscape Ecology, she evaluated how both changing land use and climate may impact insecticide use throughout the U.S. While both are expected to increase future insecticide use, crop composition and farm characteristics are highly influential.

Unfortunately, national data does not provide the same high-resolution information as Kern County, Larsen explained. She plans to continue her work to bridge the detail and scale gap to better understand how land use impacts agricultural pests and pesticide use.

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Global analysis of forest management shows local communities often lose out

UNIVERSITY OF MANCHESTER

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VIDEO: FOREST MANAGEMENT 1 view more 

CREDIT: THE UNIVERSITY OF MANCHESTER

Maintaining forest cover is an important natural climate solution, but new research shows that too often, communities lose out when local forest management is formalised.

The new study published today in Nature Sustainability, led by Dr Johan Oldepkop at The University of Manchester and Reem Hajjar at Oregon State University, is based on 643 case studies of community forest management (CFM) in 51 different countries, from 267 peer-reviewed studies.

It provides the most comprehensive global analysis of CFM to date and shows that whilst CFM policies often have positive environmental and economic impacts, CFM often results in weakened rights and less access to forests for local populations.

Around the world, 1.6 billion people live within 5km (3 miles) forest, with 71% located in low or middle income countries.

"Improving forests can be a vital way to both tackle climate change and address poverty - however, our study shows that too often local communities lose out when the management of community forests is formalised by governments," said Dr. Oldekop. "With the clock ticking on catastrophic climate change, the world needs to learn from successes in countries like Nepal, where we saw some cases with simultaneous economic, environmental, and resource rights outcomes."

Previous research by Dr. Oldekop demonstrated that community-forest management in Nepal led to a 37% relative reduction in deforestation and a 4.3% relative reduction in poverty.

Around the globe, forests regulate climate, sequester carbon, are home to a large proportion of the worlds plants and animals and contribute substantially to the livelihoods of people living in or near them.

"Around 14% of forests worldwide and 28% of forests in low-middle-income countries are formally owned or managed by Indigenous people and local communities," said Reem Hajjar. "Case studies that show positive outcomes abound. But gaining a better understanding of the trade-offs - this outcome got better but at the expense of other outcomes getting worse - is critical for understanding forest governance systems' potential for addressing multiple sustainability objectives at the same time".

The new study analysed 643 examples of CFM in Latin America, Africa and Asia-Pacific, to gain a better understanding of the social, economic and environmental trade-offs which are occurring and what changes can help ensure goals across the spectrum are successful.

• Of the 524 cases that tracked the environmental condition of a forest following a formalised CFM initiative, 56% cited improvement but for 32% it decreased.
• Of the 316 cases that reported on livelihoods, 68% found an increase in income, 36% showed no change and 6.3% reported a fall.
• Among the 249 cases reporting on resource access rights, 34% indicated an increase compared to 54% that showed a decrease.

However, clear trade-offs were visible in cases which assessed joint outcomes. Of the 122 studies which looked at all three CFM goals, just 18% reported positive outcomes across the three goals.

"Community Forest Management can improve both forests and the lives of the people near them. While it is heartening to see improving incomes in 68% of cases, reduced environmental impacts in 56% and gains in resource rights in 34% of cases, the overall results are significantly less transformative than they could be. Governments need to do more to ensure it's a triple win for people and the environment, rather than a series of trade-offs between them," added Dr Oldekop.

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YouTube video: https://youtu.be/Onbi6SVMRYo

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Forest management 1

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For asymbiotic growth of arbuscular mycorrhizal fungi, feed them fatty acids

SHINSHU UNIVERSITY

Research News

 

IMAGE: SCIENTISTS AROUND THE WORLD HAVE BEEN WORKING TO GROW ARBUSCULAR MYCORRHIZAL FUNGI WITHOUT THEIR HOST PLANTS BECAUSE THEY CAN BE USED AS ORGANIC FERTILIZER IN AGRICULTURE AND FORESTRY. AM FUNGI... view more 

CREDIT: ASSOCIATE PROFESSOR KATSUHARU SAITO, SHINSHU UNIVERSITY, JAPAN

Scientists around the world have been working to grow arbuscular mycorrhizal fungi without their host plants because they can be used as organic fertilizer in agriculture and forestry. AM fungi help plants receive nutrients from the soil through a network that is efficient and far more reaching than their own roots can provide. A group led by graduate students Yuta Sugiura, Rei Akiyama and Associate Professor Katsuharu Saito of Shinshu University successfully demonstrated that AM fungi can be grown asymbiotically when given myristate as a carbon and energy source.

The history of the relationship between AM fungi and plants growing on land goes back 460 million years. For the first time in its 460 million year history, arbuscular mycorrhizal is about to gain independence from plants, so that it can be used to help plants grow in less fertile soil. Corresponding author Professor Saito states "although it was considered difficult, AM fungi has been successfully grown in a culture medium. With advancements, microbial materials for agricultural use can be produced."

"The growth speed and efficiency is still low and we are working on spore formation so the next generation can be grown. We hope to work on a collection of cultures that can be grown independently and be applied for use in agriculture." Currently, the only way for AM fungi to be used in agriculture is with their host plants, making its use as fertilizer expensive and hard to implement. With the advancement in asymbiotic culture, the hope is that less chemical fertilizer will be needed for use in agriculture.

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For more information, please read: Myristate can be used as a carbon and energy source for the asymbiotic growth of arbuscular mycorrhizal fungi

 

Distinct slab interfaces found within mantle transition zone

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

Research News

 

IMAGE: SEISMIC OBSERVATIONS (A) AND A CONCEPTUAL CARTOON SUMMARIZING THE ORIGIN OF IMAGED SLAB INTERFACES (B) view more 

CREDIT: CHEN QIFU'S GROUP

Oceanic lithosphere descends into Earth's mantle as subducting slabs. Boundaries between the subducting slab and the surrounding mantle are defined as slab interfaces, whose seismic imaging is the key to understanding slab dynamics in the mantle. However, the existence of slab interfaces below 200 km remains elusive.

Prof. CHEN Qifu's group from the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) and their collaborators observed two distinct seismic discontinuities within the mantle transition zone (~410 km to 660 km) beneath the western Pacific.

The two discontinuities represented the upper and lower boundaries of the subducted Pacific high-velocity slab, corresponding to the slab Moho and the surface of partially molten sub-slab asthenosphere, respectively.

This work was published in Nature Geoscience on Nov. 9.

The subduction process transports chemically differentiated and hydrated rocks into Earth's mantle, driving the cycles of heat and material changes between Earth's surface and its deep interior.

At shallow depths (<200 km), a variety of seismic reflection studies of subduction zones have identified the upper and/or lower interfaces of subducting slabs, all of which are characterized by sharp seismic velocity discontinuities.

The slab interfaces can be seismologically detected at shallow depths. However, how deep the seismic velocity discontinuities at slab interfaces can extend remains unclear, mainly due to the lack of high-resolution imaging of slab interfaces at depths below 200 km.

To understand the existence and origin of deep slab interfaces, the researchers took advantages of the dense seismic arrays in northeast China to study the upper mantle structures in the region.

They found sharp-dipping, double seismic velocity discontinuities within the mantle transition zone (~410 km to 660 km) beneath the western Pacific that coincide spatially with the upper and lower bounds of the high-velocity slab.

"Based on detail seismological analyses, the upper discontinuity was interpreted to be the Moho discontinuity of the subducted slab," said Prof. CHEN. "The lower discontinuity is likely caused by partial melting of sub-slab asthenosphere under hydrous conditions in the seaward portion of the slab."

The imaged distinct slab-mantle boundaries at depths between 410 and 660 km, deeper than previously observed, suggest a compositionally layered slab and high-water contents beneath the slab.

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The study was done in collaboration with California Institute of Technology, Rice University, China University of Petroleum (Beijing), Earth Observatory of Singapore, Nanyang Technological University, Peking University, Institute of Earthquake Forecasting, China Earthquake Administration, and University of Illinois Urbana-Champaign.

The work was supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences and the National Natural Science Foundation of China.

 

One third of UK fruit and vegetables are imported from climate-vulnerable countries

LONDON SCHOOL OF HYGIENE & TROPICAL MEDICINE

Research News

 

The UK's supply of fruit and vegetables has become increasingly reliant on imports from countries vulnerable to climate change, according to a new study in Nature Food.

The research, led by the London School of Hygiene & Tropical Medicine (LSHTM), involved analysing open-source data on food trade from 1987-2013. They estimated that the domestic contribution to total fruit and vegetable supply in the UK has decreased from 42% in 1987 to 22% in 2013, while at the same time imports of fruit and vegetables from climate-vulnerable countries have increased from 20% in 1987 to 32% in 2013.

The team found that the variety of fruits and vegetables imported into the UK has increased, and that there have been major shifts in the types of fruits and vegetables supplied to the UK market: tropical fruits have become more popular, but the supply of traditional vegetables has significantly declined.

In 1987, 21 crops comprised the top 80% of total fruit and vegetables supplied to the UK, and this rose to 27 in 2000 and 34 in 2013. The supply of pineapples increased from 0.9% to 1.4% of overall fruit and vegetable supply, and bananas from 3% to 7.8%, over this period.

Cabbages declined from 7.5% in 1987 to 2.5% of overall fruit and vegetable supply, peas from 5.0% to 1.3% and carrots from 7.0% to 5.8%.

Given the projected trends in global climate change, the researchers say that increased reliance on fruit and vegetable imports from climate-vulnerable countries could have a negative impact on the availability, price and consumption of fruit and vegetables in the UK. The researchers used a range of indices to assess the vulnerability of countries to current and future climate change. The analysis suggests that the most affected groups are likely to be people in low-income households.

Fruit and vegetables are key components of healthy diets, but globally their consumption is well below current international dietary recommendations. Just 30% of adults and 18% of children eat the recommended five portions of fruit and/or vegetables per day in England. Fruit and vegetables also typically have lower environmental footprints than animal sourced food and this dual contribution to health and sustainability is becoming increasingly recognised.

Dr Pauline Scheelbeek from LSHTM's Centre on Climate Change & Planetary Health, who led the study, said: "The UK's current trade patterns and climate change means the supply of fruit and vegetables in the UK is not secure. The recognition that trade is a key component of food system resilience is therefore vital information for policymakers.

"The increased reliance on fruit and vegetable imports from climate-vulnerable countries will, if no adequate climate change adaptation measures are taken in the production countries, lead to fruit and vegetable supply problems in the UK and potentially affect price and consumption of such foods. This could be a major challenge in our efforts to promote higher fruit and vegetable consumption in the UK, both for health and environmental reasons."

Professor Alan Dangour, Director of the Centre on Climate Change & Planetary Health at LSHTM, said: "It is very clear from the underlying trends in food production and trade that the UK is increasingly reliant on climate-vulnerable countries for its supplies of fruit and vegetables. The government cannot ignore these trends or it will be failing in its primary duty to protect its people from future shocks. I call on the government to do more now to support national food production, build resilience into the national food system and ensure the supply of healthy and sustainable diets for all."

The research team say that the results are particularly important in the light of several government- led programmes, such as the UK's National Food Strategy, the National Determined Contributions of the UK, and the Obesity Strategy, as well as ongoing Brexit trade negotiations.

Dr Pauline Scheelbeek, said: "The implications of vulnerability of our trade strategy cuts across traditional policy silos such as diets, health, agriculture, economy and the environment. We need to rethink our trade strategy to reduce dependency on climate vulnerable countries, import responsibly and look into possibilities to enhance consumption of sustainably grown fruit and vegetables, including those produced in the UK."

The study is subject to some limitations. The openly available trade data relies on reporting from individual countries, which may vary in quality. The indices used to determine climate vulnerability are modelled estimates and determined at country level: the vulnerability of the specific locations of crops production may not be the same as the country average.

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For more information or interviews, please contact press@lshtm.ac.uk.

A copy of the embargoed paper is available upon request.

Link to when paper goes live

Notes for Editors

Pauline FD Scheelbeek, Cami Moss, Thomas Kastner, Carmelia Alae-Carew, Stephanie Jarmul, Rosemary Green, Anna Taylor, Andy Haines, Alan D Dangour. UK's fruit and vegetable supply increasingly dependent on imports from climate vulnerable producing countries. Nature Food. DOI: 10.1038/s43016-020-00179-4

The London School of Hygiene & Tropical Medicine (LSHTM) is a world-leading centre for research, postgraduate studies and continuing education in public and global health. LSHTM has a strong international presence with over 3,000 staff and 4,000 students working in the UK and countries around the world, and an annual research income of £180 million.

LSHTM is one of the highest-rated research institutions in the UK, is partnered with two MRC University Units in The Gambia and Uganda, and was named University of the Year in the Times Higher Education Awards 2016. Our mission is to improve health and health equity in the UK and worldwide; working in partnership to achieve excellence in public and global health research, education and translation of knowledge into policy and practice. http://www.lshtm.ac.uk

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of new

 

Researchers present wild theory: Water may be naturally occurring on all rocky planets

UNIVERSITY OF COPENHAGEN THE FACULTY OF HEALTH AND MEDICAL SCIENCES

Research News

 

The emergence of life is a mystery. Nevertheless, researchers agree that water is a precondition for life. The first cell emerged in water and then evolved to form multicellular organism. The oldest known single-cell organism on Earth is about 3.5 billion years old.

So far, so good. But if life emerged in water, where did the water come from?

"There are two hypotheses about the emergence of water. One is that it arrives on planets by accident, when asteroids containing water collide with the planet in question," says Professor Martin Bizzarro from the Centre for Star and Planet Formation at the Faculty of Health and Medical Sciences, University of Copenhagen.

Together with Assistant Professor Zhengbin Deng he has headed a new study that turns the theory about the emergence of water upside down.

"The other hypothesis is that water emerges in connection with the formation of the planet. Our study suggests that this hypothesis is correct, and if that is true, it is extremely exciting, because it means that the presence of water is a bioproduct of the planet formation process," Martin Bizzarro explains.

If Martin Bizzarro and Zhengbin Deng's theory proves correct, life in planetary systems may have had better chances of developing than previously assumed.

The researchers' studies show that there was water on Mars for the first 90 million years of the planet's existence. In astronomical time, this is a long time before water-rich asteroids bombarded the planets of the inner Solar System like Earth and Mars, according to the first hypothesis. And this is very sensational', Martin Bizzarro explains.

"It suggests that water emerged with the formation of Mars. And it tells us that water may be naturally occurring on planets and does not require an external source like water-rich asteroids," he says.

The study is based on analyses of an otherwise modest black meteorite. But the meteorite is 4.45 billion years old and contains invaluable knowledge about the young solar system. Black Beauty, which is the name of the meteorite, originates from the original Martian crust and offers unique insight into events at the time of the formation of the solar system.

"It is a gold mine of information. And extremely valuable," says Martin Bizzarro. After having been discovered in the Moroccan desert, the meteorite was sold for USD 10,000 dollars per gram.

With help from funds, Martin Bizzarro managed to buy just under 50 grams for research purposes back in 2017. With the meteorite in the laboratory they are now able to present signs of the presence of liquid water on Mars at the time of its formation. First, however, they had to crush, dissolve and analyse 15 grams of the expensive rock, Zhengbin Deng explains:

"We have developed a new technique that tells us that Mars in its infancy suffered one or more severe asteroid impacts. The impact, Black Beauty reveals, created kinetic energy that released a lot of oxygen. And the only mechanism that could likely have caused the release of such large amounts of oxygen is the presence of water," Zhengbin Deng says.

Another bone of contention between researchers is how Mars with its cold surface temperature could accommodate liquid water causing the depositions of rivers and lakes visible on the planet today. Liquid water is a precondition for the assembling of organic molecules, which is what happened at least 3.5 billion years ago at the emergence of life on Earth.

The researchers' analysis of Black Beauty shows that the asteroid impact on Mars released a lot of greenhouse gasses into the atmosphere.

According to Zhengbin Deng, 'this means that the CO2-rich atmosphere may have caused temperatures to rise and thus allowed liquid water to exist at the surface of Mars'.

The team is now doing a follow-up study examining the microscopic water-bearing minerals found in Black Beauty. The age-old watery minerals are both original and unchanged since their formation, which means that the meteorite has witnessed the very emergence of water.

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A biomimetic membrane for desalinating seawater on an industrial scale

CNRS

Research News

 

The treatment of seawater, including its large-scale desalination, is a major challenge for our society. Reverse osmosis[1] is one of the most widely used techniques for the desalination of water. Some of the membranes currently used are artificial channels of water[2] inserted into lipid layers. But their large-scale performance is not satisfactory under real osmotic pressure and salinity conditions. An international team, involving researchers from KAUST (Saudi Arabia) and Politehnico di Torino (Italy) and coordinated by scientists from the Institut Européen des Membranes (CNRS/ENSC Montpellier/University of Montpellier), has developed a hybrid strategy, which consists of combining a polyamide matrix and artificial water channels into a single structure. Their membranes, which take the form of a sponge superstructure, have been tested under industrial conditions and outperform conventional membranes. Their flow is 75% higher than that observed with current industrial membranes and they require about 12% less energy for desalination. Their work is patented[3] and was published on November 9, 2020 in Nature Nanotechnology.

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Notes

1 Reverse Osmosis is a system of purifying water through a filtering system that only allows water molecules to pass through. Salt and other impurities do not pass through the filter membrane.

2 Artificial water channels are synthetic compounds that form pores permeable to water molecules, while rejecting ions.

3 Patent FR1910152, PCT/EP2020/075162, "Membrane biomimétiques composites à canaux artificiels d'eau".

 

Cutting emissions makes North Atlantic focus of ocean heat uptake under global warming

INSTITUTE OF ATMOSPHERIC PHYSICS, CHINESE ACADEMY OF SCIENCES

Research News

 

IMAGE: CUTTING EMISSIONS MAKES THE NORTH ATLANTIC THE FOCUS OF OCEAN HEAT UPTAKE UNDER GLOBAL WARMING. view more 

CREDIT: GANG HUANG

The Earth is getting warmer at a faster rate than ever. 93% of the net energy is absorbed by global ocean surface in the form of the Ocean Heat Uptake (OHU), which is the key factor modulating the rate of global warming.

The Southern Ocean (surrounding the Antarctic continent, south of 30°S ) plays a dominant role in global OHU while the North Atlantic takes a small share.

Future emissions of greenhouse gases (GHGs) and aerosols in the 21st century will be different from those in the historical period (since 1850), according to a new study published in Science Advances on Nov. 6.

The study was conducted by researchers from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences and their collaborators from University of California Riverside (UCR).

The researchers revealed the effects of aerosols and GHGs on regional OHU under different future warming scenarios. Based on the target of the 2015 Paris Agreement that limits global warming of 1.5°C or 2°C above pre-industrial levels by 2100, the new study first found the hemispheric asymmetry of OHU and its reasons under a low-emission scenario.

It also found that during the 21st century, the projected OHU showed collectively positive trends in the North Atlantic and Southern Ocean under the high-emission scenario. While under the low-emission scenario, as compared to the negative long-term trend of Southern Ocean OHU, North Atlantic OHU had a positive long-term trend, which makes the North Atlantic the focus of global OHU in the future.

The opposite OHU trends in the Southern Ocean could be attributed partially to distinct GHG trajectories under the two scenarios. While the common positive OHU trends in the North Atlantic in the two scenarios were due to the total effects from anthropogenic aerosols and GHGs.

The researchers also presented that projected decline in anthropogenic aerosols induced a weakening of the AMOC and divergence of meridional ocean heat transport, which leads to enhanced OHU in the North Atlantic.

Previous studies have found that comparing to the historical period, from the middle to high emission scenarios, the North Atlantic OHU takes more and more percentages in global OHU while the Southern Ocean OHU takes less and less share even though the Southern Ocean still contributes most to global OHU. However, the regional OHU change under the low-emission scenario is not well understood.

"We discover an obvious hemispheric asymmetry in OHU under the low-emission scenario. In the long term, North Atlantic OHU keeps increasing and will become the main region of OHU. Our finding reveals the importance of aerosol effects and AMOC influences, which are helpful to the attribution of climate events," said the lead author Xiaofan Ma, a Ph.D. candidate from IAP.

"To sustain the balance of Earth's ecosystem, human societies have been taking measures to slow down the global warming. Our work shows the scientific significance of the low-warming target. It also helps us to better understand and project the climate change under low-emission scenarios," said the corresponding author Prof. Gang Huang from IAP.

Huang also noted that due to the limits of observations, these results rely on the climate model simulations. He looks forward to carrying out further studies with the development of ocean observation systems and datasets.

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Half a billion years old microfossils may yield new knowledge of animal origins

UPPSALA UNIVERSITY

Research News

 

IMAGE: NORTHERN GREENLAND'S PORTFJELD FORMATION, MORE THAN HALF A BILLION YEARS OLD, CONTAINS EMBRYO-LIKE MICROFOSSILS. view more 

CREDIT: JOHN PEEL

When and how did the first animals appear? Science has long sought an answer. Uppsala University researchers and colleagues in Denmark have now jointly found, in Greenland, embryo-like microfossils up to 570 million years old, revealing that organisms of this type were dispersed throughout the world. The study is published in Communications Biology.

"We believe this discovery of ours improves our scope for understanding the period in Earth's history when animals first appeared - and is likely to prompt many interesting discussions," says Sebastian Willman, the study's first author and a palaeontologist at Uppsala University.

The existence of animals on Earth around 540 million years ago (mya) is well substantiated. This was when the event in evolution known as the "Cambrian Explosion" took place. Fossils from a huge number of creatures from the Cambrian period, many of them shelled, exist. The first animals must have evolved earlier still; but there are divergent views in the research community on whether the extant fossils dating back to the Precambrian Era are genuinely classifiable as animals.

The new finds from the Portfjeld Formation in the north of Greenland may help to enhance understanding of the origin of animals. In rocks that are 570-560 mya, scientists from Uppsala University, the University of Copenhagen and the Geological Survey of Denmark and Greenland have found microfossils of what might be eggs and animal embryos. These are so well preserved that individual cells, and even intracellular structures, can be studied. The organisms concerned lived in the shallow coastal seas around Greenland during the Ediacaran period, 635-541 mya. The immense variability of microfossils has convinced the researchers that the complexity of life in that period must have been greater than has hitherto been known.

Similar finds were uncovered in southern China's Doushantuo Formation, which is nearly 600 million years old, over three decades ago. Since then, researchers have been discussing what kinds of life form the microfossils represented, and some think they are eggs and embryos from primeval animals. The Greenland fossils are somewhat younger than, but largely identical to, those from China.

The new discovery means that the researchers can also say that these organisms were spread throughout the world. When they were alive, most continents were spaced out south of the Equator. Greenland lay where the expanse of the Southern Ocean (surrounding Antarctica) is now, and China was roughly at the same latitude as present-day Florida.

"The vast bedrock, essentially unexplored to date, of the north of Greenland offers opportunities to understand the evolution of the first multicellular organisms, which in turn developed into the first animals that, in their turn, led to us," Sebastian Willman says.

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Willman, S. Peel, J. S., Ineson, J. R., Schovsbo, N. H., Rugen, E. J. & Frei, R. (2020) Ediacaran Doushantuo-type biota discovered in Laurentia. Communications Biology. DOI:10.1038/s42003-020-01381-7

 

RUDN University soil scientist: Deforestation affects the bacterial composition of the soil

RUDN UNIVERSITY

Research News

 

IMAGE: A SOIL SCIENTIST FROM RUDN UNIVERSITY STUDIED THE EFFECT OF FOREST CONVERSION ON THE PROPERTIES OF THE SOIL: ITS ACIDITY, CARBON AND NITROGEN RESOURCES, BACTERIAL COMPOSITION, AND THE ACTIVITY OF... view more 

CREDIT: RUDN UNIVERSITY

A soil scientist from RUDN University studied the effect of forest conversion on the properties of the soil: its acidity, carbon and nitrogen resources, bacterial composition, and the activity of microorganisms. The study can help improve the methods of soil cultivation after deforestation, namely, select the best fertilizers, prevent erosion, slow down nutrient depletion, and balance the composition of the bacterial community. The results of the study were published in the Forest Ecology and Management journal.

The demand for crop farming products grows constantly, and to satisfy it, more and more forests are converted into plantations. In these converted areas sustainable and diverse ecosystems are replaced with monocultures (crop species). Such changes in land utilization affect both the chemical content of the soil and its biological composition, that is, the structure of its microbial community. Until recently, studies had focused on either the former or the latter aspect of this process. A soil scientist from RUDN University was the first to conduct a comprehensive study and to find out how deforestation and changes in chemical factors caused by it affect the bacterial composition of the soil.

"The diversity of soil microorganisms doesn't necessarily reduce as a result of forest conversion. However, bacterial communities undergo massive transformations. The bacteria that used to dominate in forest soils can almost disappear after deforestation and planting of crops. The key factors in this process are soil acidity and carbon and nitrogen resources," says Yakov Kuzyakov, a Ph.D. in Biology, and the Head of the Center for Mathematical Modeling and Design of Sustainable Ecosystems at RUDN University.

His team compared soil samples taken from a forest and four plantations in Hunan Province in South-Eastern China. Five years before that the whole territory had been covered with a pristine forest. The scientists measured the acidity of the soil, as well as the levels of carbon and nitrogen in it. All these indicators are associated both with soil fertility and bacterial activity. Microorganisms play a role in the circulation of soil carbon and also 'fix' nitrogen, making it accessible for plants. It turned out that soil acidity reduces after deforestation, and the levels of organic nitrogen and carbon drop by 83%. According to the team, this may be due to the reduction of vegetative cover and soil erosion. However, to the team's surprise, bacterial diversity in plantation soils turned out to be 6.8% higher than in forest soils.

The scientists believe this might be due to the fertilization of plantations. Fertilizers contain a lot of nutrients, thus increasing microbial diversity. Moreover, cultivated soil is enriched in carbon and other substances that also support intensive bacterial growth. Reduced acidity might be another factor to promote microbial and especially bacterial diversity. Different bacteria turned out to dominate in forest and plantation soils. For example, deforestation created perfect conditions for photosynthesizing bacteria. They transform sunlight into energy, which is a much more difficult task in shady forests.

"We found out that changes in the bacterial composition of the soil are mainly due to soil acidity and the levels of organic carbon and nitrogen. Therefore, efficient soil management methods should be developed for monoculture plantations to improve fertilization, prevent soil erosion, slow down the depletion of nutrients, and support microbial activity after deforestation," added Yakov Kuzyakov.

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