Threatened grasslands key to carbon capture solutions

Prairie grasslands store billions of tonnes of carbon dioxide in their soil, playing a critical role in the mitigation of climate change, yet over 80 per cent of Canada’s grasslands have been lost. They are the single most threatened ecosystem in Canada.

Climate Action Through Grazing (CAT-G), an innovative research project co-led by ecologist James Cahill in the Department of Biological Sciences and Carolyn Fitzsimmons, a research scientist for Agriculture and Agri-Food Canada, aims to bolster conservation efforts through better grassland management and methane gas emissions reduction. The objective is to store an additional 32.5 million metric tonnes of carbon in Canadian grasslands to help meet the goal of net zero emissions by 2050, positioning Canada as a global leader in rangeland sustainability. 

It’s an ambitious goal, aided by a large, cross-disciplinary team of experts in collaboration with ranchers and farmers. 

Now in the second of a four-year project, CAT-G is taking a holistic approach to the research, examining conditions above and below the ground, including the socio-economic impacts.

“We want our work to be translational into working ranches, rather than purely an academic study,” says Cahill, who leads the vegetation and soil team. “Conservation can’t be solved without making these systems biologically and economically sustainable.”

Fitzsimmons, co-located within the Department of Agricultural, Food & Nutritional Science, agrees. “In carbon cycling or carbon sequestration you have to measure what happens in the soil, what happens in the animal, what happens to the waste that animal produces and how it fits in that carbon cycling system,” she says. “We're looking at different grazing systems, rotational vs. continuous grazing, and at feed efficiency. Cattle that have better feed efficiency produce less methane — a major driver of global warming.”

Western Canada’s grasslands are made up of hundreds of species of plants, a mix of native and introduced varieties. In central Alberta, located at the northernmost edge of this massive transnational grassland system (just below the boreal forest transition zone), grasslands are under constant threat of being converted to croplands or some other type of development. 

“Grazed lands are largely on private property in Canada,” says Cahill. “Individual ranchers and producers face economic pressures that favour conversion, and the only way to have a large-scale conservation effort in grasslands is to ensure profitability so that the producers have long term sustainability.”

Cattle are conservation agents

Beef and dairy cattle account for the majority of Canada's agricultural methane emissions, contributing to the public perception that cows are the problem, but as Cahill notes, if you remove cattle from the landscape, the grasslands naturally convert to woodlands and shrubs, which in terms of carbon sequestration, are not as efficient and far less reliable.

Cahill calls grasslands a disturbance maintained ecosystem. To maintain the ecosystem, he says, you need a combination of grazing, fire and drought. Fires are stopped, and droughts can’t be controlled, so the only thing that can be controlled is the grazing. That is why it is the most important conservation tool for maintaining grasslands. 

“Cattle are a conservation agent,” says Cahill. “They are what’s preserving grasslands in Canada right now.” 

The research is being conducted on two University of Alberta Rangeland Research Institutes, the Mattheis Ranch and Kinsella Research Ranch, which have seen a positive impact as a result of the project in terms of new infrastructure and the influx of research funds — contributing to the long-term research potential at both ranches.

Over the last year, plant, soil microbial community composition and methane emission data under grazing conditions designed to mimic existing operational systems have been collected. Once fully analyzed, this data will serve as a comparative model against the experimental dual grazing techniques underway this year. 

CATG has received significant interest and support from various stakeholders, including international experts and industry partners. Plans to extend the experiment for longer-term data collection are in development.

“We are demonstrating that the processes that are the result of cattle grazing can be managed better,” says Fitzsimmons. “We hope to manage our animals in a way that actually improves carbon sequestration over the long term and preserves grasslands in Western Canada. That’s one of the reasons why there is excitement around this project: people realize there hasn’t really been a voice for producers who are trying to manage their lands with a sustainability aspect in mind.”