When the heat is on: pasture recovery after fire or drought

Following years of drought and a record-breaking wildfire season, pastures across Alberta are in poor condition. We asked rangeland ecologist Cameron Carlyle to bring us up to speed on the situation and provide some recommendations on how to help pastures recover.

Across Alberta, wildfires and drought reduced available grazing acres in 2023, resulting in heavy use on grazable land. Whether as a result of drought, fire or overgrazing, damaged pastures need time to recover and, given adequate moisture and rest, they usually will.

The effects of fire and drought on a pasture differ, both at the surface level and below it. Fire generally does the most damage to the surface, stripping all vegetation including important plant litter. Drought damages both plant vigour on the surface and root reserves deeper in the soil.

How quickly pastures recover from both kinds of damage depends heavily on moisture. “The litter layer is super important for holding moisture in the ground and contributing to forage production, and in a fire all the vegetation burns up,” explains Cameron Carlyle, Associate Professor of Rangeland Ecology at the
University of Alberta. “In drought conditions, plants have less root energy reserves and less vigour because they didn’t have the same growth opportunity the year before.”

Carlyle has been active in pasture productivity research in Alberta for many years. In one study, his team looked at grassland recovery following grass fires in southern Alberta and southern Saskatchewan in 2017, comparing grazed versus ungrazed areas. While grazing impacted forage recovery, the biggest single factor was rainfall. “When the rain came, that’s when we started to see recovery,” he says.

Long-range forecasts suggest rainfall in 2024 may not be sufficient in many areas of the province. While we can’t make the rain fall, Carlyle offers some valuable suggestions based on his research to support pasture recovery.

MAINTAIN HEALTHY PASTURES

In every corner of the province, making a concerted effort to maintain rangeland health is important. It increases resilience in case of either fire or drought. “Generally we find that drier areas of the province tend to be more sensitive to drought and to overgrazing, and possibly that is true of fire as well,” says Carlyle.

Carlyle’s research found that areas that had higher range health prior to fire recovered a bit faster. “This suggests that maintaining good range management practices does help provide some resilience when fires happen,” he says.

GIVE IT A REST

On drought or fire-damaged acres, support recovery by providing adequate rest. Carlyle’s grassland fire recovery research found that grazing during the recovery period slowed the development of surface litter. “It might look okay if there is rainfall and you see plants growing, but the litter layer needs time to develop to create drought resilience in the system,” he says.

The only constant is knowing that conditions will continue to change.

MONITOR RECOVERY

While allowing a pasture to rest, producers can monitor plant height and vigour, and watch for changes in the types of vegetation present. The key following a fire is to focus on the developing litter layer. “You can take photos or do a litter scrape in the years following a fire to see how well the litter layer is developing over time,” Carlyle suggests.

PATIENCE PAYS OFF

Generally, Carlyle recommends practicing patience. “Monitor forage growth and reduce stocking rates on drought or fire affected areas as much as possible,” he says.

The amount of time required for damaged pastures to recover varies. Carlyle’s research found that after four years, forage production on grassland recovering from fire returned to the same level as it was in areas that hadn’t burned. But even after four years, the litter layer hadn’t recovered. He adds: “Other studies have shown that where there was above average rainfall in the years following drought or fire, recovery happened very quickly. So, it depends.”

CHANGE IS A CONSTANT

There’s no question – producers dealing with drought or fire damaged pastures are in a tough situation right now, and the only constant is knowing that conditions will continue to change. Hopefully, for the better.

“Producers have to graze when animals need to be fed,” says Carlyle. “But if possible, I recommend avoiding grazing for a year on an area that burned. Following drought, the same applies – as much as possible, you want to reduce the use of those pastures.”

This article was first published in Volume 4 Issue 1 of ABP Magazine (February 2024). Watch for more digital content from the magazine on ABP Daily.