Farms that create habitat key to food security and biodiversity
It seems intuitive that forests would provide better habitat for forest-dwelling wildlife than farms. Yet, in one of the longest-running studies of tropical wildlife populations in the world, Stanford researchers found that over 18 years, smaller farms with varying crop types – interspersed with patches or ribbons of forest – sustain many forest-dependent bird populations in Costa Rica, even as populations decline in forests.
In a paper published Sept. 4 in the Proceedings of the National Academy of Sciences, Nicholas Hendershot and colleagues compared trends in specific bird populations across three landscape types in Costa Rica: forests, diversified farms, and intensive agriculture. The steepest declines were found in forests, then in intensive agriculture (and the species succeeding in intensive agriculture were often invasive). But on diversified farms, a significant subset of bird species typically found in forests, including some of conservation concern, actually increased over time.
“Birds are kind of a proxy we use to track the health of ecosystems. And the birds we’re seeing today aren’t the same as we saw 18 to 20 years ago. This paper really documents this pattern,” said Hendershot, a postdoctoral fellow at the time of this research in Stanford’s Department of Biology in the School of Humanities and Sciences (H&S), the Stanford Center for Conservation Biology (CCB), and the Stanford-based Natural Capital Project (NatCap).
Food security at stake
While this research implies that diversified farming could be key for biodiversity, the relationship goes both ways: biodiversity is key for food security. In this case, that means having a variety of types of birds feeding on insects and helping to pollinate crops.
“Identity does seem to matter a lot for pest control and other ecosystem services birds provide. These species are not interchangeable,” said Hendershot.
“We need a constant stream of pollinators servicing farms. About three-quarters of the world’s crops require pollinators to some extent, and that 75% is our most nutritious food – think of all the vitamins and minerals packed into fruits, nuts, and veggies,” explained Gretchen Daily, faculty director of NatCap and CCB, Bing Professor of Environmental Science in H&S, and a senior author on the paper. “We need a constant stream of birds, bats, and other wildlife to help control pests: they suppress the vast majority naturally. And we need to start building flood protection, water purification, carbon storage, and many other vital benefits back into agricultural landscapes, way beyond what can be achieved in protected areas alone.”
Daily also noted that, in terms of food production, diversified farms are not necessarily lower yielding than intensive agriculture. “This is a recent assumption that is being overturned,” she said.
Beyond protected areas
It has become increasingly apparent around the world that while protected areas remain critical, they are too few and far between to provide the ecosystem services people and nature need to thrive. Working landscapes are crucial now for preserving biodiversity and its benefits. “People, including scientists, had the idea that farmland would not support a meaningful amount of biodiversity,” said Daily. In this case, not only are diversified farms themselves providing habitat, they connect otherwise fragmented forested areas.
Over time, Hendershot said, “I have moved away from the ‘fortress conservation’ model, which focused more on creating protected areas separate from human activities, and see more and more how much potential there is outside of forests. The forests are key – we need them, of course. But in addition to that, I’m always surprised by how important how you manage a farm is for biodiversity.”
“We believe the findings of our research are new to science, but in a sense, it merely confirms what Indigenous communities around the world have already known for a long time, which is that humans can and should have reciprocal relationships with the rest of the local ecological community they are part of,” said Tadashi Fukami, a professor of biology in H&S and of Earth system science in the Stanford Doerr School of Sustainability and a co-author of the paper.
Incentivizing farmers
In the 1980s and 90s, deforestation was occurring in Costa Rica at the fastest rate ever seen on a country scale. Then, they turned it around – becoming a renowned model of success. By setting up the world’s first countrywide payment for ecosystem services (PES) program, Costa Rica reversed this trend: today, forests cover almost 60% of its land, up from 40% in 1987.
The country currently aims to double the amount of protected forest in just a few years. In its existing PES program, any landowner can receive money for reforesting even small parts of their land. Now, the government is also working toward a new PES program to incentivize farmers to adopt best management practices.
This study will help inform Costa Rican policymakers in understanding the benefits provided over time by different farming practices. Said Daily, “We need to recognize the vital work many farmers are doing that supports biodiversity.”
Nicholas Hendershot was a postdoctoral researcher with the Center for Conservation Biology at Stanford and is now a forest ecologist with The Nature Conservancy-California. Gretchen Daily is also a senior fellow in the Stanford Woods Institute for the Environment. Other co-authors on the paper are Alejandra Echeverri, a senior scientist at the Natural Capital Project, Luke Frishkoff of the University of Texas at Arlington, and prominent Costa Rican ornithologist Jim Zook.
Hendershot’s work was supported by the Gerhard Casper and John P. Morgridge Stanford Graduate Fellowship, the OTS Emerging Challenges in Tropical Science Fellowship, and the Winslow Foundation. Funding for data collection from 1999-2017 was generously provided to Daily by the LuEsther T. Mertz Charitable Trust, the Moore Family Foundation, and the Winslow Foundation.
JOURNAL
Proceedings of the National Academy of Sciences
ARTICLE TITLE
Diversified farms bolster forest-bird populations despite ongoing declines in tropical forests
ARTICLE PUBLICATION DATE
5-Sep-2023
Mary Swansburg
Mon, September 4, 2023
Eoghan Daltun has held many titles in his lifetime — farmer, sculptor, and now author and activist for conservation in rural Ireland. In the past 14 years, he has undertaken an effort to restore the native wildlife to the Beara hillside.
The Beara hillside is known for its beautiful landscapes and historical remains of the Bronze Age, but 15 years ago, the wildlife wasn’t an accurate representation of Ireland’s biodiversity. A large portion of the native plants were stripped away as a result of an overabundance of animals that feed on them and invasive plant species.
In an interview with the Guardian, Daltun described the area as “biologically empty” and explained how he began to remedy this by purchasing and rewilding a portion of the land.
Rewilding prioritizes the natural biodiversity of an area — it involves reintroducing previously pushed-out species and restoring the local wildlife to a landscape. The process allows the native plants and animals in the area to flourish as they did before other factors — like invasive species and human intervention — made that difficult.
According to the Guardian, native forests used to make up 80% of Ireland’s landscape, and by the time the Daltun began rewilding, that number had shrunk to 1%.
His strategy included removing invasive, non-native plants — such as rhododendron — and adding fencing to keep non-native animals. These animals, such as sika deer, are known to damage trees by stripping their bark and causing harm to their trunks, as well as eating shoots and seedlings, making it difficult for wildlife to grow.
After removing the elements that made it difficult for the native wildlife to thrive, it was a waiting game to see when the ecosystem would rebuild itself — and Daltun reported that it began the process shortly after.
It’s not just native species that benefit from rewilding, though — restoring healthy, natural wildlife produces cleaner air and water, as well as perks for local buildings and the economy.
A thick tree canopy slows down the speed at which rain gets to the ground, and the roots anchor the soil — decreasing flooding and erosion. Plus, the natural beauty can stand alone as a tourist attraction — giving the local economy a boost.
Daltun told the Guardian that the transformation began immediately, but the restoration was still a gradual process. Over the years, previously suppressed wildlife began to truly flourish in the area. There is now a noticeable abundance of native wildlife, and Daltun describes how the soil was healthier and taking in more water — faring well in a recent drought.
“The result was amazing,” Daltun added.
His contribution was impressive and well appreciated — but it’s important to remember that you don’t need to have the same kind of time or funds to dedicate to the movement. This article by Mossy Earth has some great ways to help the conservation effort — some of which are free or take only a few minutes.
“We either start protecting the little natural habitats we have left, or we lose them,” Daltun told the Guardian.
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