After autumn harvest, some farmers in the Lake Erie basin spray fertilizer on newly planted fields of wheat. The fertilizer lightly penetrates the rich, sandy soil and sits dormant till spring.
This simple, long-held growing strategy supercharges the growth of new crops when spring snowmelt and rain mix with latent fertilizer to jump-start the growing season. The result is more bountiful and resilient crops, which help feed the world and improve global food security. But climate change has complicated the ecological impact of those fertilizer treatments, to the point of endangering dozens of native species.
“The fastest time of year in terms of climate change has come in the shoulder seasons,” said Dr. Kevin McCann, a mathematical ecologist, professor in the Department of Integrative Biology at the University of Guelph, and a Food from Thought researcher.
“[The] two seasons bump up against each other, and they generate the greatest extreme events”.
McCann’s research with Food from Thought has focused on the impact of climate change—specifically, extreme weather events—and the interconnectedness of food systems. “I believe all these problems can be solved, and I’m a pro-agriculture person,” said McCann. “ We need to feed the world; our argument is, we need to think of this at a landscape scale.”
With funding from Food from Thought, McCann and his team modelled nutrient movement and food webs on land, showing that “fast water” ecosystems greatly destabilized larger ecosystems in Lake Erie.
“Fast water” describes the rapid flow of rainwater and snowmelt off farmers’ fields and into surrounding watercourses through tile drainage, rows of pipes under a field that remove excess water. When extreme weather events increase the flow of water, tile systems carry nutrients into the lake, sparking massive and toxic algal blooms that can negatively impact fish, birds and water quality.
When these algal blooms die and settle at the bottom of the lake, bacteria colonize them and absorb much of the ecosystem’s available oxygen. This makes it impossible for other species to survive, resulting in what researchers call a “dead zone.”
“This is novel science,” said McCann. “People really often do not understand the implications of increased connectivity and how it can have fundamental implications across ecosystems. Nutrients put on a field 100 kilometres away can lead to a collapse of an ecosystem through a dead zone,” said McCann. Dead zones pose an existential threat to some animal species, causing a decline in biodiversity that also affects human diets and food security. Moreover, toxins from the algae can enter the food chain, creating additional threats to human health.
“The goal here is to use science to develop ‘slow water’ landscapes that allow the maintenance of productive farms while reducing nutrients, and promoting biodiversity, carbon storage and flood control,” said McCann. “ Erie is a model for this, but this is worldwide,” he added. “Wherever there is land modification that creates fast-water landscapes and high nutrient systems …. You’re going to have the same process that happens over and over again on repeat.
McCann and co-authors demonstrate in a recently published paper in Nature Ecology & Evolution that many of the practices we have developed to maximize productivity in our agricultural landscapes have substantial consequences for ecosystem services and biodiversity. Termed the ‘productivity-stability trade-off’, McCann argues that we need to consider these long-term landscape scale consequences and how they will impact sustainable food production.
McCann is also the director and a co-founding member of the Centre for Ecosystem Management (with Dr. John Fryxell), where scientists, policy-makers and other stakeholders from many disciplines collaborate on sustainability measures in the Great Lakes basin. McCann draws a straight line between Food from Thought and the Centre’s creation in 2022.
“I honestly think without Food from Thought, I wouldn’t be sitting here today, in this position, doing this thing,” he said. “It made myself and John Fryxell work with a variety of different ag people, geographers … and it opened up this sort of world of questions that come out of that. The funding was great, but it was also just that ability to sit in rooms and hear people that are doing things. It’s amazing as a scientist, or any kind of thinker.”
The productivity-stability trade-off
Illustrated by Hope Jesmer
Read more about Dr. McCann’s research in a recent U of G News article.
