Friday, October 17, 2025

Research shows how Dust Bowl-type drought causes unprecedented productivity loss

Extreme, prolonged drought conditions in grasslands around the world would greatly limit the long-term health and productivity of these crucial ecosystems

Colorado State University

Grassland research center 2 — image:
The Semi-arid Grassland Research Center in northern Colorado. One of the sites used for the International Drought Experiment. Credit: Colorado State University College of Natural Sciences
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Credit: Colorado State University College of Natural Sciences

A global research effort led by Colorado State University shows that extreme, prolonged drought conditions in grasslands and shrublands would greatly limit the long-term health of crucial ecosystems that cover nearly half the planet. The findings are particularly relevant as climate change increases the possibility of more severe droughts in the future – potentially leading to a situation that echoes the Dust Bowl of the 1930s.

The new research published in Science shows that losses in plant productivity – the creation of new organic matter through photosynthesis – were more than twice as high after four years of continued extreme drought when compared to losses from droughts of moderate intensity. The work shows that these grassland and shrubland ecosystems lose their ability to recover over time under prolonged dry conditions.

“We show that – when combined – extreme, multi-year droughts have even more profound effects than a single year of extreme drought or multi-year moderate droughts,” said CSU Biology Professor Melinda Smith, who led the study with Timothy Ohlert, a former CSU postdoctoral researcher.

“The Dust Bowl is a good example of this,” she continued. “Although it spanned nearly a decade it was only when there were consecutive extremely dry years that those effects, such as soil erosion and dust storms, occurred. Now with our changing climate, Dust Bowl-type droughts are expected to occur more frequently.”

Smith designed and led the International Drought Experiment with more than 170 researchers around the world. For the project, researchers built rainfall manipulation structures that reduced each rainfall event by a target amount over a four-year period in grassland and shrubland ecosystems across six continents. The CSU research team includes University Distinguished Professor Alan Knapp, Professor Eugene Kelly, Associate Professor Daniela Cusack and Research Associate Anping Chen. Former Ph.D. student Amanda Cordiero and Postdoctoral Researcher Lee Dietterich also contributed to the study.

By simulating 1-in-100-year extreme drought conditions, the team was able to study the long- and short-term effects on grasslands and shrublands, which store more than 30% of global carbon and support key industries, such as livestock production. Variations in precipitation, as well as soil and vegetation across continents, meant different sites experienced different combinations of moderate and extreme drought years – providing unique experimental conditions that informed this study.

Smith said the paper highlights the interaction between extremity and duration in drought conditions and that this interaction has rarely been systematically studied using experiments.

She added that the research suggests that the negative impacts on plant productivity are also likely to be much larger than previously expected under both extreme and prolonged drought conditions.

Plant growth is a fundamental component of the global carbon cycle. That is because plant photosynthesis is the main way carbon dioxide enters ecosystems, where animals consume it and plants store it as biomass. Because grasslands and shrublands cover roughly 50% of the Earth’s surface, they play a large role in balancing and facilitating carbon uptake and sequestration globally. That means changes to these ecosystems caused by drought could have wide-ranging impacts, Knapp said.

“An additional strength of this research is that the scale of the experiment matches the extent of these important grassland and shrubland ecosystems,” Knapp said. “This allowed us to show how widespread and globally significant these extreme drought impacts can be.”

For more than a decade, Smith, Knapp and their colleagues have worked on similar research into grasslands at CSU. They often partner with agencies like the Department of Agriculture to develop a better understanding of the consequences of climate change to these ecosystems on topics such as species diversity. The International Drought Experiment is a key example of this work. The team recently published findings in PNAS from the same multi-site research network that quantified the impact of extreme short-term (one year) drought on grassland and shrubland ecosystems. Smith said the pair of papers now form an important foundation for further research into this topic.

“Because of the historic rarity of extreme droughts, researchers have struggled to estimate the actual consequences of these conditions in both the near and long-term,” she said. “This large, distributed research effort is a truly a team effort and provides a platform to quantify and further study how intensified drought impacts may play out.”

Journal

Science

DOI

10.1126/science.ads8144

Article Title

Drought intensity and duration interact to magnify losses in primary productivity

Article Publication Date

16-Oct-2025

Grassland research at CSU video [VIDEO]

Colorado State University Department of Biology ecologists Melinda Smith, Alan Knapp and Kate Wilkins discuss why grasslands are important ecosystems, and how they will be impacted with climate change.

YouTube: https://www.youtube.com/watch?v=3qD2rzn4vLc

The Semi-arid Grassland Research Center in northern Colorado is one of the sites used for the International Drought Experiment.

Credit: Colorado State University College of Natural Sciences

Rainout shelters at the Purdue Wildlife Area, near West Lafayette, Indiana, reduced precipitation in a restored prairie as part of the International Drought Experiment

Credit Credit Jeffrey Dukes

Experiment site Allmend in Switzerland.

Credit: Andreas Stampfli, Bern University of Applied Sciences

An experiment test site in the cloud forests of the Kosñipata Valley, Peru

Credit David Bartholomew

New study overturns long-held assumptions about how plants spread to islands

A new study from Iceland’s Surtsey island shows that birds carried most of the plants that colonised the island, challenging long-held beliefs that seed or fruit shape determines how plants spread —

Náttúrufræðistofnun

When the volcanic island of Surtsey rose from the North Atlantic Ocean in 1963, it offered scientists a once-in-a-lifetime opportunity to observe how life takes hold on a brand-new and barren land. For decades, ecologists believed that plants’ ability to reach remote and isolated places depended mainly on special adaptations for long-distance dispersal — for example, fleshy fruits thought to attract birds, which would eat the fruit and later disperse the seeds — giving those species a decisive advantage in colonising new areas.

A new study published in Ecology Letters challenges this long-standing view. Researchers from Iceland, Hungary, and Spain found that most of the 78 vascular plant species that have colonised Surtsey since 1965 lack any of the traits traditionally associated with long-distance dispersal. Instead, gulls, geese, and shorebirds have played the leading role in bringing seeds to the island — carrying them in their guts or droppings. In doing so, birds have transported a wide range of plant species, laying the foundations for Surtsey’s developing ecosystem.

“Birds turned out to be the true pioneers of Surtsey — carrying seeds of plants that, according to conventional theories, shouldn’t be able to get there,” says Dr. Pawel Wasowicz of the Natural Science Institute of Iceland, one of the study’s authors. “These results overturn traditional assumptions about plant colonisation and show that to understand how life spreads and responds to environmental change, we must look at the interactions between plants and animals. Life does not move in isolation — it follows life.”

Dr. Andy Green from the Estación Biológica de Doñana (CSIC, Spain), who co-led the research, adds:

“Our findings have far-reaching implications for ecology and conservation. Animals — especially birds — are key drivers of plant dispersal and colonisation. As migration routes shift under a warming climate, birds will play a vital role in helping plants move and adapt to new environments.”

The study underscores the exceptional importance of Surtsey as a natural laboratory, where scientists can observe the fundamental processes of life — how ecosystems emerge, evolve, and respond to environmental change. It calls for new ecological models that account for real biological interactions rather than relying solely on seed traits or taxonomic classifications.

“Long-term research like that carried out on Surtsey is invaluable for biology,” says Dr. Wasowicz. “It allows us to witness ecological processes that would otherwise remain invisible — how life colonises, evolves, and adapts. Such work is essential for understanding the future of ecosystems in a rapidly changing world.”

Plants colonising lava field on Surtsey island

Credit

Pawel Wasowicz