Farms with diverse crops protect animals and the climate

Farms with diverse crops can help protect wildlife and buffer against climate change, researchers report.

The researchers found that farms with diverse crops planted together provide more secure, stable habitats for wildlife, and are more resilient to climate change than the single-crop standard that dominates today’s agriculture industry.

The research provides a rare, long-term look at how farming practices affect bird biodiversity in Costa Rica.

Coffee is one of the best crops for growing in a diversified landscape because it is sensitive in the heat and can use the shade of taller plants. Here, the single-crop system directly exposes the coffee to the powerful sun. (Credit: Nick Hendershot)

“Farms that are good for birds are also good for other species,” says coauthor Jeffrey Smith, a graduate student in the biology department at Stanford University. “We can use birds as natural guides to help us design better agricultural systems.”

By and large, the team found that diversified farms are more stable in the number of birds they support, provide a more secure habitat for those birds, and shield against the effects of climate change much more effectively than single-crop farms.

“…local farming practices really matter in protecting biodiversity and building climate resilience.”

“The tropics are expected to suffer even more intensely in terms of prolonged dry seasons, extreme heat, and forest dieback under climate change,” says senior author Gretchen Daily, director of the Stanford Natural Capital Project and the Center for Conservation Biology. “But diversified farms offer refuge—they can buffer these harmful effects in ways similar to a natural forest ecosystem.”

The findings highlight the importance of farms that grow multiple crops in a mixed setting instead of the more common practice of planting single-crop “monocultures.”

“This study shows that climate change has already been impacting wildlife communities, continues to do so, and that local farming practices really matter in protecting biodiversity and building climate resilience,” says lead author Nick Hendershot, a graduate student in the biology department.

‘One-two punch’

Tropical regions are some of the most species-rich in the world, but they also face the greatest threats to biodiversity. As their forests are felled to plant cash crops like bananas and sugarcane, the amount and availability of natural habitats have shrunk dramatically. Meanwhile, climate change has resulted in longer, hotter dry seasons that make species survival even more challenging.

“It’s the one-two punch of land-use intensification and climate change,” Hendershot says. “Wildlife populations are already severely stressed, with overall decreased health and population sizes in some farming landscapes. Then, these further extreme conditions like prolonged drought can come along and really just decimate a species.”

Until now, little had been known about how agricultural practices affect biodiversity in the long term. This study’s researchers used nearly 20 years of meticulously collected field data to understand which birds live in natural tropical forests and in different types of farmland.

“Each bird serves a unique role as part of the machinery of nature. And the habitats they live in support us all.”

“It is only because we had these unusually extensive long-term data that we were able to detect the role of diversified farmlands in helping threatened species persist over multiple decades,” says senior author Tadashi Fukami, an associate professor of biology.

The varied agricultural systems at work in Costa Rica provided the research team with an ideal laboratory for studying bird communities in intensively farmed monoculture systems, diversified multi-crop farms, and natural forests. They compared monoculture farms—like pineapple, rice, or sugar cane—to diversified farms that interweave multiple crops and are often bordered by ribbons of natural forest.

The many benefits of farms with diverse crops

Surprisingly, the researchers found that diversified farmlands not only provide refuge to more common bird species, they also protect some of the most threatened. Species of international conservation concern, like the great green macaw and the yellow-naped parrot, are at risk in Costa Rica due to habitat loss and the illegal pet trade.

In intensive monocrop farmlands, these species are declining. But in the diversified systems the researchers studied, the endangered birds can be found year after year.

“Which species are in a given place makes a huge difference—it’s not just about numbers alone, we care about who’s there,” Daily says. “Each bird serves a unique role as part of the machinery of nature. And the habitats they live in support us all.”

In Costa Rica and around the world, the researchers see opportunities to develop integrated, diversified agricultural systems that promote not only crop productivity and livelihood security, but also biodiversity. A paradigm shift towards global agricultural systems could help human and wildlife communities adapt to a changing climate, Daily says.

“There are so many cash crops that thrive in diversified farms. Bananas and coffee are two great examples from Costa Rica—they’re planted together, and the taller banana plant shades the temperature-sensitive coffee bean,” she adds. “The two crops together provide more habitat opportunity than just one alone, and they also provide a diversified income stream for the farmer.”

The research appears in Nature.

Source: Stanford University

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