Overgrazing is threatening global drylands

Sheep on Green Grass Field
Photo Credit: Gökçe Gök

The positive effects of grazing by livestock and wild herbivores can turn negative as temperatures become warmer.

Grazing is a trillion-dollar industry, and is particularly important in drylands, which cover about 40 percent of Earth's land surface and support half of the world’s livestock. Livestock are critical for food, shelter and a source of capital, but changing climates threaten livestock production and the livelihoods of billions of people worldwide.

An international team of scientists has published a study in the journal Science today with the first global estimates of how grazing will affect ecosystem services across the world’s drylands. The research, led by the Dryland Ecology and Global Change group in Spain with collaborators from UNSW Sydney, shows that grazing by livestock and wild herbivores in drylands can have positive effects on ecosystem services, but these effects can turn negative as Earth’s temperature becomes warmer.

What Is: An Ecosystem

The Holocoenotic Nature of the Biosphere
Image Credit: Scientific Frontline / stock image

The Genesis of a Paradigm 

The concept of the ecosystem represents one of the most significant intellectual leaps in the history of biological science. It is not merely a label for a collection of living things, but a sophisticated framework that integrates the chaotic multiplicity of the natural world into a coherent, functional unit. To understand the ecosystem is to understand the fundamental architecture of life on Earth. This report provides an exhaustive analysis of the ecosystem concept, tracing its historical lineage, dissecting its thermodynamic and biogeochemical engines, exploring its diverse manifestations across the globe, and evaluating its resilience in the face of unprecedented anthropogenic pressure. 

Grassland Ecosystems Become More Resilient with Age

In diverse plant communities, evolution increases the division of labor between species over time.
Photo Credit: Alexandra Weigelt

Reduced biodiversity affects the stability of the entire ecosystem. A long-term experiment now shows that grassland plant communities with multiple species need about 10 years to adjust to each other and produce an even amount of biomass again.

Recent experiments have shown that the loss of species from a plant community can reduce ecosystem functions and services such as productivity, carbon storage and soil health. This reduced functioning may also destabilize the ecosystem in its ability to maintain ecosystem functions and services in the long term. However, assessing this is only possible if experiments can be maintained for a sufficient length of time.

Stable biomass production after 10 years

In a new study, researchers from the University of Zurich and colleagues from Leipzig and Jena analyzed the stability of plant biomass production over two decades in one of the longest-running grassland biodiversity experiments in the world, the Jena Experiment in Germany. After more than a decade, plant species in more diverse experimental communities complemented each other in producing stable biomass at the community level. At low plant diversity, by contrast, this “compensatory” effect was observed and community biomass varied much more from year to year. During the first decade of the experiment, species-rich communities had not yet stabilized because of large fluctuations in species populations. This long-term research shows that biodiversity plays an increasingly important role in stabilizing ecosystem productivity over time as plant communities mature.

Ecology: In-Depth Description

Photo Credit: Глеб Коровко

Ecology is the scientific study of the interactions between living organisms and their environment, including both living (biotic) and non-living (abiotic) components. Its primary goals are to understand the principles governing the distribution, abundance, and relationships of organisms, as well as the flow of energy and materials within ecosystems.

Apex predators in prehistoric Colombian oceans would have snacked on killer whales today

. Illustration of some of the apex predators in the Paja Formation biota with a human for scale.
Illustration Credit: Guillermo Torres, Hace Tiempo, Instituto von Humboldt.

Predators at the top of a marine food chain 130 million years ago ruled with more power than any modern species, McGill research into a marine ecosystem from the Cretaceous period revealed. 

The study, published in the Zoological Journal of the Linnean Society, reconstructs the ecosystem of Colombia’s Paja Formation, and finds it was teeming with marine reptiles reaching over 10 meters in length that inhabited a seventh trophic level.  

Trophic levels are the layers or ranks within a food chain that describe the roles organisms play in an ecosystem based on their source of energy and nutrients. Essentially, they help define who eats whom in an ecosystem. Today’s marine trophic levels cap at six, with creatures like killer whales and great white sharks. 

The discovery of giant marine reptile apex predators occupying a seventh trophic level underscores the Paja ecosystem’s unmatched diversity and complexity, offering a rare view into an evolutionary arms race among predators and prey. 

Marine heat waves disrupt the ocean food web in the northeast Pacific Ocean

Pyrosomes.
Photo Credit: Mark Farley, Hatfield Marine Science Center, Oregon State University.

Marine heat waves in the northeast Pacific Ocean create ongoing and complex disruptions of the ocean food web that may benefit some species but threaten the future of many others, a new study has shown.

The study, just published in the journal Nature Communications, is the first of its kind to examine the impacts of marine heat waves on the entire ocean ecosystem in the northern California Current, the span of waters along the West Coast from Washington to Northern California.

The researchers found that the biggest beneficiary of marine heat waves is gelatinous zooplankton – predominantly cylindrical-shaped pyrosomes that explode in numbers following a marine heat wave and shift how energy moves throughout the food web, said lead author Dylan Gomes, who worked on the study as a postdoctoral scholar with Oregon State University’s Marine Mammal Institute.

“If you look at single species interactions, you’re likely to miss a lot,” Gomes said. “The natural effects of a disturbance are not necessarily going to be straightforward and linear. What this showed us is that these heat waves impact every predator and prey in the ecosystem through direct and indirect pathways.”

The project was a collaboration by Oregon State University and the National Oceanic and Atmospheric Administration. Joshua Stewart, an assistant professor with the Marine Mammal Institute, mentored Gomes and co-authored the paper.

The many ways nature nurtures human well-being

Visitors leisurely enjoy an iris garden in Japan. Of all the pathways linking a single cultural ecosystem service to a single constituent of well-being captured from the academic literature, 86.3% represented positive contributions compared to just 11.7% negative contributions. 
Resized Image using AI by SFLORG
Credit: 2022 Nicola Burghall CC-BY-NC

A systematic review of 301 academic articles on “cultural ecosystem services” has enabled researchers to identify how these nonmaterial contributions from nature are linked to and significantly affect human well-being. They identified 227 unique pathways through which human interaction with nature positively or negatively affects well-being. These were then used to isolate 16 distinct underlying mechanisms, or types of connection, through which people experience these effects. This comprehensive review brings together observations from a fragmented field of research, which could be of great use to policymakers looking to benefit society through the careful use and protection of the intangible benefits of nature.

Do you ever feel the need for a bit of fresh air to energize yourself, or to spend time in the garden to relax? Aside from clean water, food and useful raw materials, nature provides many other benefits that we might overlook or find it hard to grasp and quantify. Research into cultural ecosystem services (CESs), the nonmaterial benefits we receive from nature, aims to better understand these contributions, whether they emerge through recreation and social experiences, or nature’s spiritual value and our sense of place.

Hundreds of CESs studies have explored the connections between nature and human well-being. However, they have often used different methods and measurements, or focused on different demographics and places. This fragmentation makes it difficult to identify overarching patterns or commonalities on how these intangible contributions really affect human well-being. Better understanding them could aid real-world decision-making about the environment, which could benefit individuals and the wider society.

Loss of nature costs more than previously estimated

Photo Credit: Christian Heitz

Researchers propose that governments apply a new method for calculating the benefits that arise from conserving biodiversity and nature for future generations.

The method can be used by governments in cost-benefit analyses for public infrastructure projects, in which the loss of animal and plant species and ‘ecosystem services’ – such as filtering air or water, pollinating crops or the recreational value of a space – are converted into a current monetary value.

This process is designed to make biodiversity loss and the benefits of nature conservation more visible in political decision-making.

However, the international research team says current methods for calculating the values of ecosystem services “fall short” and have devised a new approach, which they believe could easily be deployed in Treasury analysis underpinning future Budget statements.

Their approach, published in the journal Science, takes into consideration the increase in monetary value of nature over time as human income increases, as well as the likely deterioration in biodiversity, making it more of a scarce resource.

Urban birds prefer native trees

Urban great tits prefer native trees for breeding
Photo Credit: Sandra Alekseeva

Small passerine birds, such as blue and great tits, avoid breeding in urban areas where there are many non-native trees. Chicks also weigh less the more non-native trees there are in the vicinity of the nest. This is shown in a long-term study from Lund University in Sweden.

City trees contribute to several important ecosystem services such as lowering local temperature and purifying air but are also homes to birds and insects. Vegetation, especially trees, is the primary managed biological component of a city’s ecosystem. It is therefore important to understand the consequences of our planning of parks and green spaces. To find out how different types of trees affect birdlife, a research team, led by Lund University, monitored 400 nest boxes in five parks in the Swedish city Malmö over a seven-year period.

The results, now published in the scientific journal, Oecologia, show that native trees – defined in the study as species that have been in the ecosystem for at least 700 years – provide more resources and are preferred by urban birds.

New rapid method to predict effects of conservation actions on complex ecosystems

From left: Dr Matthew Adams, Sarah Vollert, Professor Drovandi
Photo Credit: Courtesy of Queensland University of Technology

A new way to analyze the effects of conservation actions on complex ecosystems has cut the modelling time from 108 days to six hours, QUT statisticians have found:

• Some conservation efforts backfire, eg eradicating feral cats could lead to rabbit explosion

• Modeling predicts the cascading effects through species in a complex ecosystem, but is computationally slow

• New method cuts prediction time from 3.5 months to six hours

PhD researcher Sarah Vollert, from the School of Mathematical Sciences and the QUT Centre for Data Sciences, said it was impossible to predict exactly how conservation actions would affect each species.

“Though well-intentioned, conservation actions have the potential to backfire,” Ms. Vollert said.

“For example, if decision-makers decide to eradicate feral cats, it could lead to explosive populations of their prey species, like rabbits.

“Uncontrolled rabbit populations could then have devastating effects on the vegetation, destroying the habitat native species need to survive.

Dry grass: Research project explores the effect of multi-year drought on grasslands

As a dry spell stretches from months to years, grasslands can adapt — to a point.
Photo Credit: Scientific Frontline / Heidi-Ann Fourkiller

A recent paper in the journal Science, “Drought intensity and duration interact to magnify losses in primary productivity,” explores how moderate and extreme droughts affect grasslands around the world. The paper has more than 180 international co-authors, with Binghamton University Assistant Professor of Ecosystem Science Amber Churchill among them.

Known as a distributed network, research projects of this type call upon collaborators to perform the same experiments locally, Churchill explained.

“The idea is that everyone uses the same methodology, but each local site is independently responsible for the maintenance of their site, data collection and ongoing measurements,” she said. “Often, individual sites will collect data in addition to the core project’s data.”

The experiment measured productivity, or how much plant biomass grows in a year. Less rain typically means less productivity, but the long-term picture is complicated by a number of factors. For one, not all grasslands are created equal; they come in a variety of types, with varying precipitation levels. Removing 10% of rainfall in an arid grassland is the equivalent of removing 40% of the precipitation in a wetter ecosystem, according to the research.

Forest Resilience Linked with Higher Mortality Risk in Western U.S.

A new study assesses decades of U.S. forest health data, revealing a twist in Western U.S. forest fate amid climate change — higher ecosystem resilience is linked with higher mortality risk
Photo Credit: Sarah Ardin

A forest’s resilience, or ability to absorb environmental disturbances, has long been thought to be a boost for its odds of survival against the looming threat of climate change.

But a new study suggests that for some Western U.S. forests, it’s quite the opposite.

In the journal Global Change Biology, researchers have published one of the first large-scale studies of U.S. forest land exploring the link between forest resilience and mortality.

The study is based on more than three decades of satellite image data used for assessing forest resilience, and more than two decades of ground observations of forest tree death across the continental United States.

The results show that while high ecosystem resilience correlates with low mortality in eastern forests, it is linked to high mortality in western regions.

“It’s a surprising finding. … It was widely assumed that greater forest resilience indicates lower mortality risk, but this relationship hadn’t been rigorously evaluated at such a large scale until now,” said Xiaonan Tai, assistant professor of biology at New Jersey Institute of Technology and the corresponding author.

Biodiversity 'time machine' uses artificial intelligence to learn from the past

Experts can make crucial decisions about future biodiversity management by using artificial intelligence to learn from past environmental change, according to research at the University of Birmingham.

A team, led by the University’s School of Biosciences, has proposed a ‘time machine framework’ that will help decision-makers effectively go back in time to observe the links between biodiversity, pollution events and environmental changes such as climate change as they occurred and examine the impacts they had on ecosystems.

In a new paper, published in Trends in Ecology and Evolution, the team sets out how these insights can be used to forecast the future of ecosystem services such as climate change mitigation, food provisioning and clean water.

Using this information, stakeholders can prioritize actions which will provide the greatest impact.

Principal investigator, Dr Luisa Orsini, is an Associate Professor at the University of Birmingham and Fellow of The Alan Turing Institute. She explained: “Biodiversity sustains many ecosystem services. Yet these are declining at an alarming rate. As we discuss vital issues like these at the COP26 Summit in Glasgow, we might be more aware than ever that future generations may not be able to enjoy nature’s services if we fail to protect biodiversity.”

Biodiversity loss happens over many years and is often caused by the cumulative effect of multiple environmental threats. Only by quantifying biodiversity before, during and after pollution events, can the causes of biodiversity and ecosystem service loss be identified, say the researchers.

New Insights into Ecosystem Functions

The mastermind behind the new statistical method: mathematician and statistician Anne Chao from National Tsing Hua University in Taiwan. Here she is in the university forest of the University of Würzburg on an experimental test plot.
Photo Credit: Simon Thorn/JMU

A DFG research group led by the University of Würzburg has developed a method that makes it possible to analyze the relationship between biodiversity within and between ecosystems and the multifunctionality of entire landscapes.

Ecosystems fulfil a number of vital tasks: They store carbon, clean polluted water, pollinate plants and so on. How well an ecosystem can fulfil these tasks depends largely on its biodiversity, i.e. the variety of plants, animals and microorganisms that live in it. Until now, scientists have only been able to understand the exact nature of this relationship at a local level, for example in relation to individual forest areas, meadows and ponds. The DFG (German Research Foundation) research group BETA-FOR, led by the University of Würzburg (JMU), has now succeeded in developing a statistical method that for the first time can also analyze the contributions of biodiversity between local ecosystems to the multifunctionality of entire landscapes.

Microbial DNA sequencing reveals nutrient pollution and climate change reinforce lake eutrophication

Lake 227 of the Experimental Lakes Area.
Photo Credit: Rebecca Garner

The algal blooms increasingly seen in Canadian lakes have been linked to both nutrient pollution from agricultural runoff and climate change. However, a new Concordia-led study using DNA sequencing of lakebed microbes reveals that these two drivers amplify each other in ways that profoundly affect the health of lake ecosystems.

Using records and samples from the International Institute for Sustainable Development Experimental Lakes Area (ELA), a group of 58 lakes in northwestern Ontario designated freshwater research facilities, the researchers paired environmental monitoring data dating back more than five decades with paleogenetic reconstructions from lakebed microbes dating back more than a century.

By sequencing DNA found in lake sediments, the researchers got insight into past algal communities’ composition and compare them to communities today. This provided critical insight into how those communities changed over decades.

“The sediment DNA archives gave us a chronology of these lakes’ history,” says lead author Rebecca Garner, PhD 2023, and currently a postdoctoral fellow at the University of California, Berkeley. “This is the first study to show that we can reconstruct the community dynamics of that ecosystem and dramatically expands the diversity of microorganisms that we were able to study.”

The study was published in the journal Environmental Microbiology.

Crayfish and carp among invasive species pushing lakes towards ecosystem collapse

Asian silver carp

Human activity and climate change are causing invasive non-native species to spread rapidly across the globe. Researchers have found that certain invasive species can push lake ecosystems beyond a critical ‘tipping point’, causing a sudden shift from healthy to degraded conditions that is difficult to reverse.

Invasive fish such as Asian silver carp Hypophthalmichthys molitrix, and crustaceans such as American signal crayfish Pacifastacus leniusculus, were found to significantly reduce the abundance of other important organisms in lakes and degrade water quality. The findings, published today in the journal Global Change Biology, also provide guidance on the best ways to manage waterbodies.

Shallow lakes naturally exist in one of two alternative stable states: either healthy - with clear water with an abundance of vegetation, or degraded - with cloudy water dominated by algae. When a lake is in the latter state, algae use up all the nutrients in the water and block sunlight, preventing the growth of aquatic vegetation that would aid ecosystem recovery.

Deteriorated, algae-dominated freshwater ecosystems also threaten the health and water security of human populations. Blooms of cyanobacteria, known as ‘blue-green algae’ can produce toxins that contaminate food webs and poison water supplies.

Development of a curious robot to study coral reef ecosystems

A grant by the National Science Foundation to researchers at the Woods Hole Oceanographic Institution (WHOI) and Syracuse University aims to open new avenues of robotic study of coral reefs by developing autonomous underwater vehicles capable of navigating complex environments and of collecting data over long periods of time. The team led by WHOI computer scientist Yogesh Girdhar aims to build a robot capable of navigating a reef ecosystem and measuring the biomass, biodiversity, and behavior of organisms living in or passing through a reef over extended periods of time.

Coral reefs support the health of the ocean and support large numbers of people worldwide. About one in four marine organisms relies on reefs at some point in their lifecycle, and hundreds of millions of people derive food, jobs, and protection from storms and erosion from reef ecosystems. A 2020 report on the status of coral reefs worldwide put the value of benefits reefs provide at $2.7 trillion per year. Despite this, reefs are in decline around the world as a result of rising temperatures, ocean acidification, pollution, and other threats. And scientists are scrambling to better understand complex reef ecosystems and devise ways to deal with a growing crisis.

“The tools we have right now to study coral reefs are pretty primitive,” said Girdhar. “The robots and the sensors we have at the moment can’t capture the spatial and temporal diversity of a reef at the same time. We want to amplify the capability of scientists in the field and the tools they’re using.”

Mussel survey reveals alarming degradation of River Thames ecosystem since the 1960s

Photo Credit: Gil Ndjouwou

The detailed study measured the change in size and number of all species of mussel in a stretch of the River Thames near Reading between 1964 and 2020.

The results were striking: not only had native populations severely declined, but the mussels that remained were much smaller for their age – reflecting slower growth.

Mussels are important in freshwater ecosystems because they filter the water and remove algae. As filter feeders they’re exposed to everything in the water, and this makes them a valuable indicator of ecosystem health. Mussel shells also provide places for other aquatic species to live.

“Mussels are a great indicator of the health of the river ecosystem. Such a massive decline in mussel biomass in the river is also likely to have a knock-on effect for other species, reducing the overall biodiversity,” said Isobel Ollard, a PhD student in the University of Cambridge’s Department of Zoology and first author of the report.

She added: “The depressed river mussel used to be quite widespread in the Thames, but this survey didn’t find a single one - which also raises concerns for the survival of this species.”

First-of-its-kind integrated dataset enables genes-to-ecosystems research

DOE national laboratory scientists led by Oak Ridge National Laboratory have developed the first tree dataset of its kind, bridging molecular information about the poplar tree microbiome to ecosystem-level processes.
Illustration Credit: Andy Sproles/ORNL, U.S. Dept. of Energy

The first-ever dataset bridging molecular information about the poplar tree microbiome to ecosystem-level processes has been released by a team of Department of Energy scientists led by Oak Ridge National Laboratory. The project aims to inform research regarding how natural systems function, their vulnerability to a changing climate, and ultimately how plants might be engineered for better performance as sources of bioenergy and natural carbon storage.

The data, described in Nature Publishing Group’s Scientific Data, provides in-depth information on 27 genetically distinct variants, or genotypes, of Populus trichocarpa, a poplar tree of interest as a bioenergy crop. The genotypes are among those that the ORNL-led Center for Bioenergy Innovation previously included in a genome-wide association study linking genetic variations to the trees’ physical traits. ORNL researchers collected leaf, soil and root samples from poplar fields in two regions of Oregon — one in a wetter area subject to flooding and the other drier and susceptible to drought. 

Details in the newly integrated dataset range from the trees’ genetic makeup and gene expression to the chemistry of the soil environment, analysis of the microbes that live on and around the trees and compounds the plants and microbes produce.

The dataset “is unprecedented in its size and scope,” said ORNL Corporate Fellow Mitchel Doktycz, section head for Bioimaging and Analytics and project co-lead. “It is of value in answering many different scientific questions.” By mining the data with machine learning and statistical approaches, scientists can better understand how the genetic makeup, physical traits and chemical diversity of Populus relate to processes such as cycling of soil nitrogen and carbon, he said. 

Rare glimpse at understudied ecosystem prompts caution on deep-sea mining

Some of the animals identified in the deep-sea that spend their life in the benthic boundary layer.
Photo Credit: Gabrielle Ellis

An enormous but poorly understood region of the global ocean–referred to as the abyssal benthic boundary layer–lies a few meters above the seafloor and has only been sampled a handful of times. A study by oceanographers at the University of Hawaiʻi at Mānoa provided the first in-depth look at this habitat, revealing a dynamic community that may be more sensitive to seasonal changes than previously understood. The research, published in Limnology and Oceanography, also concluded that deep-sea mining could have significant and unavoidable impacts on biodiversity, regardless of the time of year.

“Given the remoteness of this environment, we have extraordinarily limited knowledge of the animals that inhabit this zone,” said Gabrielle Ellis, lead author of the study and recent oceanography graduate from the UH Mānoa School of Ocean and Earth Science and Technology. “This study represents a significant contribution to our understanding of the benthic boundary layer community, and it starts to unravel temporal dynamics in the abyss.”