A sweltering mid-June day with temperatures topping 100 degrees spurred one of the largest livestock die-offs in recent Kansas history, killing about 2,000 cattle.
Twice that many cattle perished in fierce 2011 Iowa heat, with thousands more dying in neighboring states. And a July 1995 heat wave took a similar toll in the Farm Belt.
Heat stress reduces cows’ appetite, fertility and milk production. It also suppresses their immune systems. And that is likely to happen more often as the climate warms, particularly in the Midwest and Great Plains where heat, drought, fire and flood are challenging long-standing farm practices.
Yet premature cattle mortality could be mitigated by a centuries-old land management approach used by Native tribes on what were once millions of acres of oak savannas stretching from Texas to Minnesota, according to research at the University of Missouri.
“Silvopasture” could also be an effective and inexpensive way for farmers to protect livestock against climate extremes while improving farm forest conditions for aesthetic, ecological and economic purposes. Experts say it’s a win-win for farmers, but it will require unlearning a century of conventional wisdom that brawny bovines belong on pastures and ranchlands, not forests.
“The idea is there is a sweet spot where we can manage pastureland for trees, forage and livestock,” said Ashley Conway-Anderson, an assistant research professor at the University of Missouri who is working to restore silvopasture landscapes at a research farm in the northeast Ozarks. The 1,200-acre property is predominantly woodland forest, with roughly 230 acres being managed for pasture and forage production.
In that way, the farm is largely representative of what remains of the Midwestern oak savanna, where wooded areas “aren’t really being managed at all,” Conway-Anderson said in an interview. “Livestock are kept out of the forests,” she said, “and there’s nothing happening to improve those areas for other purposes.”
Such purposes include cultivating fruits or nuts and restoring habitat for native species, many of which have seen population crashes over two centuries converting treed landscape to cropland.
Increasingly, however, scientists have found that silvopasture can be an important tool for farmers to beat back climate change — providing shelter from extreme heat and humidity, storms and floods that can destroy farms and farm economies. Silvopasturing could also save farmers millions of dollars in reduced costs for water misters and artificial shade structures that are increasingly necessary to protect cattle from heat stress.
Acute heat waves in Middle America, some of which can last for days and weeks, are becoming more common under a warming climate, scientists say. So too are quick, unpredictable hot and cold snaps that livestock is not naturally adapted to handle.
Researchers from Ohio State University and the University of Illinois found that beef and dairy cattle losses from heat stress averaged $1.26 billion annually, a figure that’s expected to rise as worsening heat and drought grip the heartland.
“Economic losses are incurred by the U.S. livestock industries because farm animals are raised in locations and seasons where effective temperature conditions venture outside their zone of thermal comfort,” the researchers wrote.
Experts say such “thermal comfort” zones are shifting, making cattle production more difficult and expensive in Southern Plains states like Texas and Oklahoma, but also in parts of Kansas, Missouri, Iowa and Wisconsin. Rangelands across the West, too, are seeing the effects of warming, particularly as drought and fire consume millions of acres annually.
According to Conway-Anderson, silvopasturing where pastures are interspersed with deciduous trees and pine stands offers benefits on both sides of the climate equation. They restore forest health through carbon absorption — a core tenet of what’s known as “regenerative agriculture” — while also protecting animals and crops from extreme heat.
“It’s adaptation in the sense that animals, like humans, are experiencing the worsening effects of our changing climate,” she said.
Healthy livestock may adapt to changing conditions over decades, she noted, but when climate change-induced extreme events cause dramatic changes in temperature, humidity or land conditions, animals don’t have time to adapt. Such events “are occurring with greater intensity, and I think it’s only going to become more of an issue,” Conway-Anderson said.
Conservation is key
But silvopasturing involves much more than allowing livestock to roam in forests or congregate around random tree stands.
According to the Department of Agriculture, it’s “the deliberate integration of trees and grazing livestock operations on the same land,” where they are “intensively managed for both forest products and forage, providing both short- and long-term income sources.”
In Missouri, Conway-Anderson is engaged in a multiyear project aimed at restoring a healthy oak savanna with the proper balance of trees, forage and open space for cattle to graze in an environmentally sustainable way.
It’s slow, hard work, she said, because many candidate forests for silvopasturing have been poorly managed or simply abandoned as U.S. agriculture became less integrative and more industrialized.
Crop farmers see forests as obstacles. Livestock farmers have long been conditioned to keep cattle out of forests, in part by professional foresters and conservationists who argue livestock damages forest habitats by indiscriminate grazing and trampling on emergent trees and fragile soils.
Conway-Anderson said the sharp distinction between farm and forest management has created a “fortress conservation” mentality that doesn’t promote true restoration of native landscapes like the oak savannas, which have been largely forgotten.
The result is “there are very, very few original remnant oak savannas left,” she said. “A lot of what we’re seeing in Missouri is second-growth,” which has little resemblance to the native forests that existed pre-colonization and provided multiple uses.
It’s an open question as to how much of the native oak savanna could be reclaimed, she said, but efforts are underway to map a once-distinct ecosystem in the heart of America.
“If we’re really going to move forward with climate adaptation and mitigation, we need to look at uplifting the Indigenous practices that were used to manage these lands before colonization,” she said. “I don’t promote it as a silver bullet, but it’s one practice we need to have … in our toolbox.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2022. E&E News provides essential news for energy and environment professionals.
