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Studying the whole ecosystem

Matthew Mitchell’s research looks at how soybeans are affected by nearby forests

How can farmers produce food while also providing more environmental and societal benefits from the land they’re managing? That is a million dollar question that Dr. Matthew Mitchell is trying to answer.

While completing his PhD in natural resource sciences at McGill, Mitchell was part of a larger, two-year study looking at how people affect ecosystem services on farmland in southern Quebec. Ecosystem services include everything from carbon storage to food production to recreation, Mitchell explains.

Mitchell’s part of the project focused on how forest patches affected adjacent soybean fields. The fields were created under the seigneurial system, and measured about 30 metres wide and 1.5 kilometres long. Forest patches ranged from a few hectares to a couple of thousand hectares in size. Some forest patches were connected to each other. Others were fragments surrounded by farmland. Mitchell studied soybean aphid populations, other insect pests, pest regulation, soybean yield and soil properties.

“We really didn’t even know if those ecosystem services were going to change as you moved away from the forest patches,” he says.

Researchers did notice differences, starting with soybean yields. Soybean yields were low, averaging about 22 bushels per acre, right next to the forest at the field’s edge. Mitchell doesn’t know why, but the reason could be anything from shading to soil compaction. But 50 to 150 metres from the forest, yield averaged almost 52 bu./ac. The rest of the field averaged just below 45 bu./ac., he says.

“So having a forest patch close to your field actually ended up benefiting crop yields, even though right next to the forest it reduced the yields,” says Mitchell.

Mitchell also saw differences in insect damage. Fields next to isolated forest fragments had less leaf damage than those next to connected forest patches. Mitchell thought the forest might be a corridor for insect pests. Farmers with fields bordering connected forest patches might want to monitor more for insect damage in southern Quebec, he says.

Aphid numbers varied significantly year to year. But they generally weren’t high enough to affect soybean yield, he says. “You might see different patterns if you were working in years where there was a big outbreak.”

Mitchell cautions that his research results are unlikely to transfer directly to other regions. Ecology and farming practices are likely to differ. The history of agriculture is also different, and that history affects things like carbon storage and soil nutrients. How those soils respond to management techniques is likely to vary as well.

But whether a farm is in southern Quebec or Manitoba’s parkland, things like field size and how much forest is left will be important, he says. Figuring out how the landscape affects ecosystem services in a given area requires someone to study them, he adds.

Perhaps the biggest take-away from Mitchell’s project is that managing landscapes at a broader level is difficult. One action won’t net a benefit in all areas, he says.

“There’s going to be trade-offs about what you want to maximize or not across the landscape.”

The next steps

Mitchell is currently working as a post-doc researcher with the University of British Columbia. He’s applied for a grant, and hopes to work with ag environmental groups such as ALUS Canada and B.C.’s Farmland Advantage.

He plans to review practices, such as fencing riparian areas, tillage techniques, and conventional vs. organic farming practices. The idea is to study how they affect specific ecosystem services, such as carbon stored in soil and pest regulation. Mitchell would then use GIS data to decide where to implement management practices within the landscape to reap those benefits.

“Are there hot spots? Are there places where if we manage a certain way, we can actually get a bunch of different services? Or are there trade-offs?”

Mitchell plans to work in the Fraser Valley, Kootenays, and southern Quebec, but that project may expand. He is also hoping to do similar work with the Nature Conservancy and CGIAR, an international ag research group, pending funding. On the urban side, Mitchell is working with researchers at the University of Queensland to study carbon storage, flood regulation, and temperature regulation in Brisbane, Australia. He’s also co-supervising a PhD student at the University of Queensland.

Researchers face challenges early in their careers

Planning agricultural landscapes requires quite a bit of coordination. “You’ve got to get multiple farmers to cooperate. You’ve got multiple governments. You’ve got all sorts of different stakeholders and actors across the landscape. So it gets a lot more complicated and harder to actually do things.”

Mitchell sees a lot of potential in his field, but he suspects that it’s “not as sexy as doing the genetic work and biotechnology and that sort of stuff.”

One of the big problems many researchers face early in their careers is funding and jobs, says Mitchell. “Once you finish your PhD, it can be quite difficult to go that next step and get a permanent position.”

Mitchell says it’s also difficult to span the divide between scientific research and on-the-ground application for farmers. He was lucky to be part of a large project that involved farm groups during his PhD, he says. And one of his goals now is to make his research relevant to farmers, something he says can be difficult.

“At least in Canada, I haven’t seen a lot of good ways to facilitate that yet.”

About the author

Field Editor

Lisa Guenther is field editor for Grainews based at Livelong, Sask. You can follow her on Twitter @LtoG.

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