Trees, drought and climate change


Droughts are not new to the Prairies, but for Colin Laroque, a researcher at the University of Saskatchewan, the summer of 2021 stood out.

“No matter what area you went to, you felt that intense lack of rain and that intense heat that really flushed out any moisture left in the uppermost soil,” he said.

Larocque specializes in past and future climates and particularly the role of trees. He and his team have developed a set of free online tools (Shelterbelt DSS at to help farmers assess their existing resources and plan new ones.

This summer’s weather has scorched western Canada from the interior of British Columbia to Alberta, Saskatchewan, Manitoba and the northern United States.

According to, there were at least nine major droughts in the 20th century, including the often-mentioned events of 1961 and 1988. 2001 began the new century with a dry year, and 2015 saw British Columbia and the parched prairie provinces. by an event partly attributed to human-induced climate change.

Climate change threatens to make such events more frequent and more serious, Laroque said. Farmers will need to build the resilience of their operations if agriculture is to survive and thrive. Trees, especially windbreaks, can play a major role.

This can be a hard sell to a farmer who is tired of miscalculating and again hanging a seed drill in the bush. Many windbreaks were planted decades ago when the equipment was much smaller. With today’s larger equipment, they can really get in the way. At harvest time, shade from windbreaks can delay the drying of windrows. Such irritations convince many farmers to get rid of pesky trees.

U of S students Scott Wood and Brooke Howat take windbreak measurements near Loreburn, Saskatchewan. Such data forms the basis of the free online windbreak decision support system. | UNIVERSITY OF SASKATCHEWAN PHOTOS

Shathi Akhter is an Agri-Ecosystems Scientist at Agriculture Canada in Indian Head, Saskatchewan. She cited information that shows that of the more than 51,000 kilometers of windbreaks in Saskatchewan, 2,490 km were lost in the eight years between 2008 and 2016, a decrease of 5%.

Before lighting the bulldozer, Laroque urges farmers to learn a lesson from the past season, and from previous generations. He and his team spent over 10 years collecting data for a shelterbelt assessment and planning tool on Saskatchewan farms.

The conversations are talking. While young farmers may be ambivalent about shelterbelts, their parents and grandparents’ long-term views are very different.

“The old people always said, ‘Keep the trees. Keep those trees. You don’t realize what they’re doing, ”Laroque said. “When you look back a lifetime, (you can see) they help you. “

The attitude of farmers towards their trees is generally positive. A survey conducted in 2014 by the Rural Development Institute at Brandon University showed that the vast majority of pastoralists rated the importance of their shelterbelts as “very important” or “important”. Farmers were less enthusiastic, but more than half had similar positive feelings.

Knowledge from Laroque and Ahkter’s research can help advocate against removing windbreaks and planting even more.

Trees are valuable, but that’s not something you can compare apples to apples to with an annual cash crop. But in a year of drought, their value is evident. Laroque said the trees catch winter snows, slow drying winds and protect crops from the worst summer sun.

“What we measured is that there is a very good moisture content in the soil up to about three heights of your windbreak. So if the windbreak is 10 meters high, it protects 30 meters in both directions.

Come out in a crop at the end of a drought year, he said, and you will find the crop is higher and heading closer to the shelterbelts. Test the soil and it will be healthier near the trees, with more organic matter.

“One of the things these shelterbelts do whether you realize it or not is that they improve the soil,” Laroque said.

Although trees compete with crops, this effect is limited. Akhter’s research on windbreak intercrops shows that the ‘competitive zone’ is around two meters, while crops in the 11 meter ‘complementary zone’ between rows of trees actually benefit from their. presence. This includes improved nutrient cycling, nitrogen mineralization, soil organic carbon, and earthworm activity.

Akhter also considers shelterbelts as crops in their own right, choosing fruit and nut species such as buffalo, sea buckthorn, hazelnut and haskap. In a presentation on the subject, she said that while the first harvests will not take place for years, there may be other benefits in the meantime.

“As nitrogen-fixing crops, bilberry and sea buckthorn will bring significant amounts of nitrogen to the soil and could be of great benefit, especially on marginal lands. “

This type of approach would create windbreaks as a crop to be harvested rather than a static asset. This would require an overhaul on the part of the farmers. In the 2014 Brandon University survey, the main barriers to planting and maintaining shelterbelts were labor, time and costs associated with planting and maintaining trees. .

If interest in Laroque’s online resource is any indication, there are plenty of farmers ready to take this step. He reports that there have been more than 50,000 visits to the site since its launch last March and that it continues to generate interest.

The Shelterbelt DSS Planner is based on 10 years of data covering every area of ​​soil in Saskatchewan. Farmers can review the location of their own land and get recommendations on what tree species to plant and in which direction shelterbelts should be oriented in order to get the maximum benefit.

Since it uses data-rich satellite maps, Laroque said it is best to use it on a computer with a landline because a robust internet connection is required.

Tree selection is also important since the climate of the Prairies is at the extreme limit of survival capacity for some species. The research team drew on records from the PFRA Windbreak Center in Indian Head to find out which species had been shipped where over the decades and how well they survived. For example, some trees like white spruce only survived in places further south where farmers had given them a lot of attention.

Another aspect of windbreaks and Shelterbelt DSS is carbon. Trees are great at capturing and sequestering carbon, and if it can be measured, it can be of value to the farmer. Laroque noted that the major parties in the last federal election all took a stance on carbon as having value, and several provinces already have carbon credit systems in place.

From a public perception perspective, windbreaks also provide a chance for farmers to push back against negative rhetoric about agriculture and climate change.

“On the one hand, running tractors, pulling crops out in the short term, so you’re carbon footprint is kind of negative,” Laroque said. “If you turn it over and say, ‘I have a whole range of shelterbelts,’ you say, ‘well, these trees sequester more carbon than we put in the exhaust. “

In the long term, he said, trees are a heritage asset, adding long-term value to any given piece of land, both for agronomic benefits and for combating climate change.

“This carbon is actually worth something or something in some provinces, not yet in ours, but it is worth something around the world. It’s going to be, ”said Laroque. “At least we’re going in that direction.

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