Disease Regulation as a Missing Ecosystem Service in Restoration Planning
This study challenges the assumption that ecosystem restoration uniformly reduces zoonotic disease risk by demonstrating through simulations that vector-borne diseases often experience transitional risk amplification during partial recovery, thereby highlighting the critical need to integrate disease-specific surveillance and sustained funding into restoration planning to secure health co-benefits.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Restoring a damaged landscape is one of the most hopeful actions humanity can take for the planet. Whether it involves planting trees in a cleared forest, cleaning up a polluted river, or bringing back wetlands, the goal is to help nature heal itself. When an ecosystem recovers, it usually becomes better at regulating its own processes, supporting more species, and even helping to control the spread of diseases that jump from animals to humans. This idea, often called "One Health," suggests that a healthy environment is a safe environment. However, the path from a broken landscape to a healthy one is rarely a straight line. Nature does not simply flip a switch from "sick" to "well." Instead, ecosystems pass through messy, transitional stages where the rules of life change, and sometimes, these changes can temporarily make things more dangerous before they get better.
A new study by researchers at Bangor University, the University of Stirling, and other institutions challenges the simple belief that restoring land always immediately lowers the risk of disease. The team used computer simulations to model how four different types of diseases—those carried by rodents, ticks, mosquitoes, and those spread through direct contact between animals and people—respond to restoration efforts. They found that while fixing an ecosystem eventually leads to safer conditions, the journey there is complicated. In some cases, the act of restoration itself creates a window of time where the risk of disease actually spikes, rising higher than it was in the degraded landscape before the work began.
The researchers built a sophisticated digital model to test these ideas. They did not just guess; they created a system that runs thousands of different possible scenarios, accounting for the uncertainty of how nature behaves. They looked at what happens when restoration is done with low, medium, or high intensity, and they even simulated what would happen if funding for these projects ran out or was delayed. The results showed that the type of disease matters immensely. For diseases carried by rodents, the risk drops steadily and quickly as the land heals. As the habitat improves, the specific conditions that allow rodent populations to explode disappear, and the threat fades in a predictable way.
However, the story is very different for diseases carried by insects like ticks and mosquitoes. In these systems, the researchers found a "hump" in the risk curve. When restoration begins, the risk of disease often goes up before it goes down. For mosquito-borne diseases, this happens because early restoration efforts often involve re-wetting the land. This creates pools of standing water that are perfect breeding grounds for mosquitoes. The predators that usually eat mosquito larvae, such as certain fish, amphibians, and birds, take time to return to the area. So, for a while, the mosquitoes have a feast, and the risk of disease transmission rises. Only after the ecosystem matures and the predator community is re-established does the risk finally crash down, eventually falling to levels much lower than where it started.
Tick-borne diseases follow a similar but slower pattern. Restoring a forest might initially connect habitats, allowing deer and other animals that carry ticks to move more freely and reproduce. The large predators that keep these animal populations in check, such as wolves or foxes, take years or even decades to return. During this long waiting period, the number of ticks can swell, creating a prolonged period of high risk. The study showed that if restoration is only partial—meaning the land is fixed up a little but not completely—the ecosystem can get stuck in this dangerous middle ground. It has enough life to support the disease vectors but not enough regulation to control them.
The timing of money and effort is just as critical as the work itself. The simulations revealed that delaying investment can be disastrous for public health. If a project waits too long to move from a small-scale effort to a large, complete restoration, the ecosystem spends more time in that dangerous "hump" phase. Conversely, if funding is cut short after a project has started, the results depend on how long the project had been running. For mosquito systems, there appears to be a critical point around five to ten years; if the project survives this long, the ecosystem becomes resilient enough that a drop in funding does not immediately undo the progress. For tick systems, which operate on a much slower timeline, cutting funding even late in the game can severely compromise the outcome, as the slow-moving predators have not yet had time to establish control.
The researchers also highlighted that the common assumption—that more restoration always equals less disease in a direct, proportional way—is often wrong. In many cases, a half-finished restoration project is worse for disease control than leaving the land alone or fixing it completely. A partially restored landscape can maintain the perfect conditions for disease to spread while failing to bring back the natural checks and balances needed to stop it. This means that restoration planners cannot just look at how many trees are planted or how much water is flowing; they must also consider how long it will take for the natural predators to return and how the landscape changes during the transition.
To help planners navigate these complex choices, the team developed a free, interactive tool that allows users to explore these scenarios. By inputting local conditions and different funding plans, decision-makers can see how their choices might affect disease risk over time. The tool does not promise a perfect prediction, but it makes the hidden risks visible. It shows that while restoring nature is essential, it requires patience, sustained funding, and a clear understanding that the road to a healthy ecosystem is not a straight line. The goal is to push through the temporary dangers of the transition phase to reach the stable, regulated state that comes only with a fully recovered ecosystem. Without this careful planning, well-intentioned efforts to heal the land could inadvertently create a temporary spike in the very risks they hope to eliminate.
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