Grassland traps carbon but measurement tricky

LUNDBRECK, Alta. — There are various incentives in Canada and the world to encourage new initiatives for carbon sequestration and offset greenhouse gas production.

Rewards for already doing those things, by maintaining healthy perennial grassland, for example, are much harder to come by.

Ed Bork, a University of Alberta range ecologist, wants to change that.

He and his colleagues are studying grasslands and grazing systems’ contributions to ecological goods and services. If those can be accurately measured, it could allow governments to devise a system to reward those who manage and graze those grasslands.

“Our leading policy makers that are looking at trying to reward agriculture producers for increasing carbon (storage), they want to be able to say that ‘we are rewarding people for storing new carbon,’ ” Bork told those at a July 10 event organized by the Foothills Forage and Grazing Association.

“It’s something I call the additionality roadblock, which means if you can’t show it’s new carbon, they’re not going to necessarily pay for it.

“Another way of thinking about it is they don’t want to pay for something they’re getting for free already. I argue that’s not the way to look at it. You need to look at it as what’s at risk of potentially being lost if we continue to convert land.”

Bork contended there is more to climate change than the burning of fossil fuels. Conversion of grassland into crop production is also a factor.

Cultivation aerates the soil, raising its temperature and increasing the activity of microbes that emit more carbon dioxide than the crop can absorb. The end result is a 40 to 60 percent reduction in the amount of carbon formerly held in the soil.

“We need to start recognizing the value of existing perennial grasslands for the carbon that is already stored there and recognize that it is at risk if we undergo land-use conversion,” said Bork.

Under current Alberta practices, a person who converts grassland to cultivated cropland, and then chooses zero tillage farming methods, is eligible for carbon offsets even though the land would subsequently sequester less carbon than it did as grassland.

It’s easy to understand the economics of cropping versus grazing from a landowner’s perspective, Bork said in an interview.

Grazing is the only revenue stream available for grassland.

“There’s nothing for species at risk. There’s nothing for consumptive wildlife species. There’s nothing for biodiversity. There’s nothing for carbon storage. There’s nothing for greenhouse gas uptake.”

Canola crops replacing grassland would generate more money but would also contribute to rising carbon dioxide levels and global climate instability and affect water quality and quantity, among other effects.

“All these things add up, but we don’t necessarily think about it along those lines,” said Bork.

“We’re undervaluing the EG and S (ecological goods and services) that are provided by these grasslands. So our fight, our crusade, is basically to push and push and push with more and more empirical data, that policy makers eventually simply can’t ignore us and have to take this into account.”

The major problem with that is the variability of grasslands in terms of soil type, vegetation, climate and microclimate.

“The question becomes how do we quantify the size of the carbon pool or the size of the sinking of greenhouse gases that’s going on within there, in a way that they can be comfortable that, if they decide to put a payment in place for offset, that they can report back to either the citizens of Canada or their international partners to say we’ve done our part to reduce emissions.”

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