LINDA WERTHEIMER, HOST:
Now to Southeastern Africa, the island-nation of Madagascar - the Earth's forests are getting smaller. As they do, they're also changing shape - from big expanses of trees to smaller forest fragments separated by roads or farmland. That's making life a struggle for many plants and animals. And in Madagascar, conservationists are beginning to ask the question, how small a forest fragment is too small? Rowan Moore Gerety reports.
ROWAN MOORE GERETY, BYLINE: The forest in Ankafobe in Madagascar's Central Highlands begins just feet from the side of the highway in a narrow, wooded valley the size of a few New York City blocks. Down a few steep steps into the shade by a small creek, you can feel the temperature change right away.
JEAN JACQUES RASOLOFONIRINA: (Foreign language spoken).
GERETY: Jean-Jacques Rasolofonirina reels off the Latin names of the three lemur species that can still be found here. Then he stops to mimic the call of a Malagasy paradise flycatcher perched on a nearby branch.
RASOLOFONIRINA: (Foreign language spoken).
GERETY: And the bird replies.
(SOUNDBITE OF BIRD CHIRPING)
GERETY: For the last 12 years, Solofo and his neighbors have managed three forest fragments on 400 acres around this spot as a community preserve. The group has about 300 members. Their funding comes from the Missouri Botanical Garden. And there's a very specific reason the Botanical Garden started paying attention.
RASOLOFONIRINA: (Foreign language spoken).
GERETY: Solofo gestured at a gnarled windswept tree at the edge of the woods with smooth, gray bark and waxy leaves. That, he says, is the sohisika.
RASOLOFONIRINA: (Foreign language spoken).
GERETY: The sohisika is found nowhere on the planet outside the rolling grasslands here. There are 15 mature trees inside the preserve and two or 300 altogether, scattered in areas with no environmental protection.
Chris Birkinshaw, the lead botanist for MBG's Madagascar Program, says the group would have liked to protect a bigger area.
CHRIS BIRKINSHAW: Of course - because it's always better. But it's - sometimes you don't have a choice. It's either small or nothing.
GERETY: Some of Madagascar's most fragmented ecosystems are also among the most critical to global biodiversity. Today, some of the niches occupied by endemic plants and animals in Madagascar are as small as a couple square miles across.
BIRKINSHAW: What you've got - if it's little, it's little. And that's - how viable that will be will depend on how much we can intervene.
STUART PIMM: When it comes to fragmentation, there's bad news, and there's worst news. And there's worse news still.
GERETY: Stuart Pimm is a Duke University biologist who studies extinction.
PIMM: The tragedy of Madagascar is what very little forest remains there is in pieces. Fragments tend to be too small to maintain viable populations of the species that occur there.
GERETY: Hundreds of species unique to Madagascar are critically endangered, meaning close to being extinct in the wild - everything from grasshoppers to tortoises, frogs, ducks, fish and lemurs. Thousands more are endangered, including many we might not even know about. And a big part of that risk comes from deforestation, whether it's logging or converting woods to farmland.
What happens with forest fragments is a bit like when a child uses scissors to cut a sheet of paper into a snowflake. You get a little less paper and lots of new edges. In forests, those edges make it easier for predators. And they're vulnerable to drought.
PIMM: And when people light the fires in the fields, which they often do every year, the fragments get eroded year by year by fires.
GERETY: And that's exactly what's happening with fire at Ankafobe.
UNIDENTIFIED MAN: (Foreign language spoken).
GERETY: On a windy hillside, Solofo spots two colleagues with the preserve returning from patrol.
UNIDENTIFIED MAN: (Foreign language spoken).
GERETY: Today, they say we can go home. Rain is on the way.
The men work in pairs, rotating in weeklong shifts throughout the dry season. Members of the association also clear 14 miles of firebreaks every year by hand. But it's not always enough.
RASOLOFONIRINA: (Foreign language spoken).
GERETY: You see the big dead trees there? That's because of fire, Solofo says. We're at the top of a hill where fire tore through Ankafobe in 2014. Two hundred members of the association came out with buckets of water and green branches to help beat back the blades. But it still wiped out years of work. Thousands of native plant seedlings were lost and a chunk of forest, too.
RASOLOFONIRINA: (Foreign language spoken).
GERETY: Solofo says the fire made the association double-down on their work. The goal is to expand these tiny forests again and maybe even reconnect them so it's easier for animals to find a mate or spread seeds as they move back and forth.
Here's Pimm, the extinction expert, again.
PIMM: Reconnecting fragments is one of the most cost-effective conservation solutions that we have because it dramatically slows down the rate of extinctions.
GERETY: Solofo says only the oldest people who live near Ankafobe can remember a time when these three fragments were connected. He hopes the youngest might live to see that come true again. For NPR News, I'm Rowan Moore Gerety in Ankafobe, Madagascar.
[EDITOR'S NOTE ON NOV. 28: This story was reported with support from the environmental news service Mongabay, which has done a series on environmental issues in Madagascar. ] Transcript provided by NPR, Copyright NPR.