source : nytimes.com
Sit on a log by the Madidi River in Bolivia at dusk and you can hear what an Amazon forest should sound like. The music includes red howler monkeys, breathy thumps from the mutum jungle fowl, droning cicadas, eerie calls locals attribute to deadly bushmaster vipers and the unhinged excitement of elusive titi monkeys. Around your feet, the beach is crisscrossed by jaguar tracks and those of the pony-size tapir, a shy beast that, if you keep quiet, will saunter out of the forest and swim across the river.
This is what scientists call an “intact forest landscape.” It’s a swath of at least 500 square kilometers (about 193 square miles, equal to 70,000 soccer fields) of unbroken forest. Because of their size, these areas have maintained all their native plant and animal life and biophysical processes. These forests still adorn parts of our planet’s tropical midsection, notably the Amazon, Congo Basin and the island of New Guinea. And they form a northern belt, the boreal forests of Canada, Russia, Alaska and Scandinavia.
Intact forests today total around 11.8 million square kilometers (about 4.6 million square miles), according to estimates by a group of researchers and organizations, including Greenpeace, Global Forest Watch, World Resources Institute, Transparent World, University of Maryland, World Wildlife Fund of Russia and Wildlife Conservation Society. That’s roughly the United States and Mexico combined. It’s about a quarter of the planet’s total forest area, the rest of which is fragmented by roads, mines, cities and agriculture. Over 7 percent has been lost since 2000. Keeping the rest is a key to turning around three stubborn global trends: climate change, the sixth great extinction crisis and the loss of human cultures.
In the tropics, intact forests hold 40 percent of the aboveground forest carbon even though they make up only 20 of those latitudes’ forests. And intact forests have been shown recently to absorb enough carbon to offset many Amazon countries’ (like Peru) total emissions. When forests become fragmented, edge effects (forest damage at created edges), drying and fire cause over 150 million tons of annual emissions — more than result from outright deforestation.
The United States Environmental Protection Agency estimates suggest that