Humans are producing more food than ever – but at what cost to the environment?
A new analysis from University of Guelph researchers, published in Nature Ecology and Evolution, says our global food systems are becoming less diverse and more vulnerable to climate change, in part due to animals and plants shrinking over time.
According to the work, our global food production systems are changing animal and plant communities towards relatively smaller and faster-growing species that rely on limited food and energy sources.
For example, the transition from forest ecosystems to wheat fields shows a shift from large, long-lived organisms (e.g., trees) to small, short-lived ones such as annual grain crops. The same happens in fisheries once top predators are fished out. Common management practices, like deepwater trawling, select for small, fast-growing species capable of outlasting the high mortality rates of harvesting. Commercial harvesting tends to also reduce the average body size of individual species.
Human management leads to vulnerable land, water ecosystems
What surprised the researchers is that this phenomenon spans both land and water ecosystems. Dr. Kevin McCann, co-author and professor at the Department of Integrative Biology in the College of Biological Science, says the team reviewed both experimental and theoretical research from farms and fisheries to develop their conclusions.
“One of the things that interested me is how the data show the same structural shifts whether this is a farm or a marine fishery,” McCann says. “The result of human management seems to always be the same.”
These ecological changes make our food system more vulnerable to changing climate conditions and extreme weather. They lower biodiversity and erode the natural mechanisms that stabilize the environment. They also change the way species interact with each other, increasing competition between them.
McCann notes this means our food webs – the interdependent food chains we rely on – become less stable, while population size and density become more variable over time.
“When we start to manage land and seascapes for food, we opt for a high-production model, changing the nature of the species present and creating food systems and ecosystems that are less resilient and so more vulnerable to things like climate change.”
More productive, but less stable food system: Trade-off we can’t ignore
Lead author and postdoctoral researcher Dr. Marie Gutgesell says this productivity-stability “trade-off” is often ignored. That is, our highly productive food systems today produce massive amounts of nutrition, but they have transformed from complex ecosystems into extremely simple land and seascapes.
Such highly productive food systems not only cause ecological harm but may also have hidden underlying costs, as it takes more fertilizers and pesticides to maintain them.
“By recognizing this trade-off, we can focus on developing more resilient food systems that restore natural heterogeneity of land and seascapes,” Gutgesell says.
To build greater food security and more resilient food systems, researchers say creating sustainable global food production systems requires what’s called landscape-scale restoration design, which aims to introduce more diversity and complexity in the environment. More naturalized areas to agricultural lands, for instance, might increase plant biodiversity and encourage the return of native pollinators. This would allow food webs to be more adaptive, fulfilling various ecosystem functions and building overall resilience.
This might also involve changing harvesting strategies to take pressure off larger-bodied mobile predators in fisheries. These top predators are important as they prevent any single species from monopolizing resources. In short, McCann explains, large predators promote the balance of organisms and act as a buffer against changes like overfishing.
The study also emphasizes the importance of weaving Indigenous knowledge systems with Western scientific approaches, as Indigenous communities have a long history of sustainably managing food production systems such that they remain productive even during climatic problems like droughts or pest outbreaks.
Study co-author Dr. Evan Fraser, director of the Arrell Food Institute, says the project sparks ideas about how to manage our global food systems in the future.
“In this day of increasingly climatic uncertainty, understanding how human impacts create additional vulnerability is vitally important,” Fraser says. “This study helps point the way to more sustainable and resilient food systems.”
The study was funded by U of G’s Centre for Ecosystem Management and the Food from Thought research program, funded in part by the Canada First Research Excellence Fund.
The Centre for Ecosystem Management is a research group committed to collaborations between scientists and policymakers to advance knowledge and inform sustainable resource management.
Co-authors included U of G researchers in ecology and food sustainability working alongside other university and non-academic partners at Colorado State University, University of Toronto Mississauga, Trinity College Dublin, Yale University and Fisheries and Oceans Canada.