In 1917, a German scientist climbed a mountainside in Sweden every day for five years to collect vegetation data. Exactly 100 years later, researchers from the University of Guelph returned to the same place and found practically nothing had changed.
With rapid ecological changes happening worldwide, this finding intrigued Dr. Andrew MacDougall, U of G professor in the College of Biological Science, who wondered: Was the unaltered mountainside an exception – or a rule?
In an ambitious study recently published in Nature Ecology & Evolution, MacDougall assembled a team of more than 80 grassland researchers worldwide. They found that grasslands are experiencing sharp increases or declines in plant production (i.e., in their biomass) depending on their location, the climate and local conditions.
In other words, grasslands have not followed uniform rules in response to global climate change. Many places, like the mountainside in Sweden, are stable and resistant to change. But on a world scale, other grasslands are undergoing dramatic changes.
Biomass decline could spell trouble for food security
If biomass is declining in some grasslands and increasing in others, that could lead to a great disparity in food production around the world, with some regions more vulnerable to climate change than others.
“Grasslands are a critical ecosystem for agriculture, and they’re a tension zone,” explains MacDougall. “If they’re too wet, they turn into shrubland or forest; if they’re too dry, they turn into deserts. This makes them very sensitive to climate change.”
As the study describes, the variability in grassland biomass seems to be related to hotter temperatures, changes in precipitation and longer growing seasons – the study found the average global growing season increased by an average of nine days since the 1980s.
And there were other surprising results.
“I had expected to see a global decline in production, but most of the world is actually getting greener and bushier,” MacDougall says.
Despite lengthened growing seasons, some sites, especially in the Arctic, showed no change in biomass at all. And though most of the sites showed increases in biomass, this might not be a strictly positive result.
“Unfortunately, a lot of the species that can keep growing are invasive,” MacDougall says. “There seems to be a genetic hardwiring in some species that means they can’t capitalize on the longer growing season and the great conditions, because they’re programmed to finish early.”
Grasslands are critical and highly diverse ecosystems, covering about a quarter of the Earth’s land surface and ranging from the Arctic tundra to woodland savannah. They support a significant portion of the world’s livestock and contribute to global food security.
As they are essential for supporting biodiversity, maintaining soil health and regulating carbon storage, the study’s findings suggest the need for locally tailored approaches to conservation, rather than a one-size-fits-all strategy.
Global data collection sparks future of grasslands research
Much of the research on grasslands has focused on remote data, which is prone to many biases. In this study, researchers collected data for 84 grassland sites since the 1980s, combining decades of remote satellite data with on-the-ground field observations – a first for grasslands research.
“The validation of remotely sensed data had never been done before on a global scale because no one had the global field data,” says MacDougall. “This collaboration allowed us to more accurately assess what is happening at sites all around the world.”
MacDougall plans to continue to monitor how grasslands respond to environmental change and to further expand the global scope of this research by inviting scientists from underrepresented areas in Africa and Asia.
“The collaborative nature of this project gives us the powerful data we need to test these complex questions,” explains MacDougall.
That a solitary endeavour on a remote Swedish mountain has sparked a major global collaboration highlights how environmental research has evolved over the last 100 years. The future of science, says MacDougall, depends on these types of collaborations across countries and disciplines.
This study was funded in part by the National Sciences and Engineering Research Council of Canada.
Written by Eleonore Lebeuf-Taylor, a writer with SCRIBE, a program for graduate students in the College of Biological Science to gain paid experience in translating research results for a non-specialist audience.