Scientists estimate the world’s population will increase to 9 billion by 2050 and agricultural production will need to increase by up to 70 percent to meet the increased demand for food, fuel, feed and fiber. At the final Heuermann Lecture of 2019, Craig Allen, director of the National Science Foundation Research Traineeship at Nebraska, and two other panelists gave hope and strategies for meeting this need while maintaining healthy agricultural ecosystems.
Allen laid out the case for using resilience theory to manage agricultural ecosystems. He told the audience of about 100 at the Nebraska Innovation Campus that resilience holds a meaning in ecology different from the more common definition used in other fields like medicine and psychology.
“Many people, when you hear resilience used casually, are talking about ‘bounce-back.’ That’s the rate of return,” Allen said. “A different idea of resilience that includes the bounce-back idea is ecological resilience. This is simply a measure of amount of disturbance that a system can withstand before it fundamentally changes in structure and function.”
To illustrate the difference between the two ideas, Allen poked a red balloon with his fingers and then a pin. The balloon showed resilience to being poked by his fingers, bouncing back to its former shape between jabs. When poked with the pin, the balloon burst and collapsed on the floor.
“Not all systems are completely flexible and bounce-back-able,” Allen said. “Sometimes the perturbation is so strong that the system collapses and there is no return. You change state.”
Ecological resilience theory recognizes a change of state can occur when an ecosystem encounters too great of a disturbance and crosses a threshold from one state to the next. For instance, a lake polluted by runoff and chemicals may not bounce back but may cross over to a degraded state with toxic algae.
“When the system is rapidly changing, we call that nonstationary, and when there are thresholds—critical thresholds, we call them—beyond which a system can’t recover, a different idea of resilience that includes the bounce-back idea is ecological resilience,” Allen said.
Both definitions can be useful, he said, but bounce-back theory fails when the system is nonstationary and contains thresholds.
In addition, people trying to use bounce-back theory on a collapsed ecosystem may have difficulty knowing what the system should bounce back to.
“Think New Orleans Ninth Ward after Hurricane Katrina,” Allen said. “To bounce back to the condition it was in before would be just a disservice to the population that lives there. It would be much better to bounce forward, or what I would call ‘transform,’ to a more desirable state of the system.”
Since degraded systems like polluted waterways, drought-stricken lands, and tree-invaded grasslands work counter to the goal of feeding the world and keeping agro-ecosystems healthy, humanity must foster resilience in healthy systems and transform degraded systems into healthy systems. However, once a system has become degraded or collapsed, it can be difficult to get it back to a healthy system or transform it into one. Undesirable systems can become resilient too.
Allen said the system may show hysteresis, meaning that the path in is not the same as the path out. As an example of this, he showed how the red balloon that released all of its air after being popped could not be fixed by trying to blow air back into it. He spoke of sandbars on the Platte River as another example.
“When we’re trying to recover sandbar-mobilized sandbar habitat when the river has changed state from the sand habitat to a wooded and invaded habitat, we have to do a lot more than just restore flows,” he said. “We have to cut trees, remove biomass, herbicide, plow to get the structure out of the sandbars, etcetera.
“So, hysteresis tells us that it is really expensive sometimes to get back to where you were, and it suggests it is better to maintain resilient systems in desirable states than to try to manage them back after they have collapsed.”
Ecological resilience has an enormous body of theory behind it that bounce-back resilience theory doesn’t, and it offers solutions for the future, Allen said.
“We can foster resilience in systems that are in desirable states,’ he said. “We can manage the tradeoffs that occur both across scales and across aspects of the system: the economic, ecological, agriculture, infrastructure, etcetera. We can avoid and manage away from critical thresholds so that we don’t cross them.”
We still need to know the long-term resilience of our current agriculture systems and whether they contain thresholds and where those thresholds may be, Allen said.
“There are ways to quantify resilience,” he said. “I’m not gong to talk about this, but as I said, there is a big body of literature out there. People are working to find what resilience is, how to identify critical thresholds, identifying leading indicators of state changes so we can manage away from them, and all kinds of other approaches, all very much in the academic realm, but with real application to real-world problems.”
The second panelist in this Heuermann Lecture, Andrea Basche, a professor in the NRT and the Department of Agronomy and Horticulture, built on Allen’s resilience talk but zeroed in on the health of agricultural soil.
Basche said that since 1850, we have lost about half of the most productive part of our soil, which is topsoil.
She also discussed a 2019 soil erosion study that indicated some Nebraska watersheds experienced soil loss that would require more than 100 years to be replenished at natural replacement rates.
“We can lose soil much more quickly than we form it,” Basche said. “We can degrade our resources over a short period of time.”
Strategies she suggested for conserving soil health to help meet increasing food demands included integrating livestock on croplands, minimizing disturbance of the soil by not tilling, diversifying the crops planted and keeping continuous crop cover on soil or roots in it.
She said that although some of the latest research indicates the U.S. agricultural industry can increase production to meet needs, this isn’t the full picture.
“Our production trends, they’re on track,” she said. “But when it comes to environmental goals, we are not on track.”
She spoke about the hypoxic zone in the Gulf of Mexico. Nutrients from U.S. farms drain into the Gulf and stimulate massive algal growth, which is decayed by oxygen-consuming bacteria. The resulting low oxygen levels can kill fish and marine life.
“To ensure sustainable intensification, we need to make sure that we have some real metrics in terms of our environment and that we’re working in earnest to achieve them,” Basche said.
The third panelist of the Heuermann lecture, Michael Forsberg, cofounder of the Platte Basin Timelapse project, focused on the importance of water to sustain ourselves and our environment.
“Water is the thing that binds us all together,” he said. “It pays no attention to what we believe, where we come from, what our political stripes are. It’s something that we have to think about.”
Forsberg and his team produced the “Follow the Water” documentary that the audience watched during dinner following the Heuermann Lecture. The Platte Basin Timelapse project communicates the importance of water through photography and documents changes on the landscape for education and research.
Michael Boehm, Vice Chancellor for the Institute of Agriculture and Natural Resources, concluded the final Heuermann Lecture of 2019.
“We really are about the production of food, fuel, feed and fiber for a growing world,” he said, “and doing that mindful of the sustainability of our natural resources: our water, our soils, our air and the people who produce the food.”
The Heuermann Lectures in the Institute of Agriculture and Natural Resources at Nebraska are made possible through a gift from B. Keith and Norma Heuermann of Phillips. The Heuermanns are longtime university supporters with a strong commitment to Nebraska's production agriculture, natural resources, rural areas and people.
Video recordings of the lectures can be watched on the Heuermann webpages.
— Ronica Stromberg, Program Coordinator