When it comes to conservation, we need to end our preoccupation with quantity - and think about quality too

While some scientists have suggested we need to protect half of Earth’s surface to preserve most of its species, new research indicates that quality, not just quantity, is vital for effective conservation efforts.

“There’s a lot of discussion about protecting ‘Half Earth’ as a minimum to protect biodiversity. The challenge is, which half do we protect?” says lead study author Stuart L. Pimm, professor of conservation ecology at Duke University’s Nicholas School of the Environment.

“The predilection of national governments is to protect areas that are ‘wild’—that is, typically remote, cold, or arid,” Pimm says. “Unfortunately, those areas often hold relatively few species. Our analysis shows that protecting even as much as half of the world’s large wilderness areas will not protect many more species than at present.”

To protect as many at-risk species as possible, especially those with small ranges, governments should expand their conservation focus and prioritize the protection of key habitats outside existing wildernesses, parks, and preserves, Pimm and his coauthors from China and Brazil say.

“If we are to protect most species from extinction we have to protect the right places—special places—not just more area, per se,” says Binbin Li, assistant professor of environmental sciences at Duke Kunshan University in China.

The team’s new study, which appears in Science Advances, uses geospatial analysis to map how well the world’s current system of protected areas overlaps the ranges of nearly 20,000 species of mammals, birds, and amphibians, the species that scientists know best.

“We found that global conservation efforts have enhanced protection for many species—for example, nearly half the species of birds with the smallest geographical ranges now have at least part of their ranges protected to a degree—but critical gaps still exist,” says Clinton Jenkins of Brazil’s Instituto de Pesquisas Ecológicas.

These gaps occur worldwide, including in biodiversity hotspots such as the northern Andes, the coastal forests of Brazil, and southwestern China, and they will continue to persist even if governments protect to up to half of the world’s remaining wild areas, the study shows.

“Certainly, there are good reasons to protect large wild areas: they provide environmental services,” Pimm says. “An obvious example is the Amazon, where the loss of the forest there might cause massive changes to the climate. But to save as much biodiversity as possible, we have to identify the species that remain poorly protected—which this paper does—and then pinpoint where they are, so we can effect practical conservation.”

Many of the unprotected habitats are small parcels of land in areas that humans already affect, disqualifying them for protection as wildernesses.

“The ‘Half Earth’ approach provides an inspiring vision to protect the world’s species,” Pimm says. “A preoccupation with concentrating on the total area protected is misleading, however. It’s quality, not quantity that matters.”

Pimm, Jenkins, and Li lead a nonprofit organization called SavingSpecies that partners with local conservation groups in South America, Asia, and other regions to protect such lands.