A new study Pervasive Defaunation of Forest Remnants in a Tropical Biodiversity Hotspot reports that local extinctions of mammals in Brazil's coastal forests is occuring at an alarming rate despite efforts to protect old growth areas. Voice of America gives us a summary—
The Atlantic forest in Brazil, once a part of the great Amazon basin on the South American continent, is suffering from widespread species loss according to a new study.
Ecologist Carlos Peres with England’s University of East Anglia and then University of Cambridge graduate student Gustavo Canale traveled through the region between 2003 and 2005. They documented 200 of the largest and least disturbed old-growth forest fragments in the vast region of the Atlantic Forest.
On average, they found only four of the 18 mammal species they were looking for. Canale, now working in Brazil at the State University of Mato Grosso, says he and Peres drew largely on information from wildlife surveys, camera traps, and interviews with local people.
The scientists were surprised that even in what looked like healthy forest cover, the larger mammals were absent. “The situation was worse than we thought,” Canale said.
“All the charismatic species,” said Peres, “the large primates, the large ungulates, brocket deer, tapirs, giant anteaters, jaguars, the large cats, all of those things are pretty much gone from even fragments that look on the surface of it, okay, in terms of forest cover.”
Hunting is the main driver of species loss on lands fragmented by deforestation. Peres says Brazilian law protects forest cover, but not wildlife in the remnant forest patches. Unless that law is changed, he says, the losses will continue.
Here's the study abstract—
Tropical deforestation and forest fragmentation are among the most important biodiversity conservation issues worldwide, yet local extinctions of millions of animal and plant populations stranded in unprotected forest remnants remain poorly explained. Here, we report unprecedented rates of local extinctions of medium to large-bodied mammals in one of the world's most important tropical biodiversity hotspots.
We scrutinized 8,846 person-years of local knowledge to derive patch occupancy data for 18 mammal species within 196 forest patches across a 252,669-km2 study region of the Brazilian Atlantic Forest. We uncovered a staggering rate of local extinctions in the mammal fauna, with only 767 from a possible 3,528 populations still persisting. On average, forest patches retained 3.9 out of 18 potential species occupancies, and geographic ranges had contracted to 0–14.4% of their former distributions, including five large-bodied species that had been extirpated at a regional scale.
Forest fragments were highly accessible to hunters and exposed to edge effects and fires, thereby severely diminishing the predictive power of species-area relationships, with the power model explaining only ~9% of the variation in species richness per patch. Hence, conventional species-area curves provided over-optimistic estimates of species persistence in that most forest fragments had lost species at a much faster rate than predicted by habitat loss alone.
Lead author Carlos Peres gave Reuters about the bottom line—
"This is bad news for conservation." Many animals had vanished even in what seemed big areas of forest with intact tree canopy, he said.
Bad news for conservation. Even when some humans set aside protected areas for "charismatic" species, other humans will hunt them down if there is no law which says they can't. Hunting them down is the default case.
The scientists urged better conservation. In Brazil, animals survived best in five forest remnants that were protected as parks. "This paper is a very big positive endorsement of more protected areas," Peres said.
Hunting is not allowed in parks. Peres thought putting an economic value on forests might also help.
Forests absorb carbon dioxide, the main greenhouse gas, as they grow and release it when they burn or rot. Between 12 and 20 percent of man-made greenhouse gas emissions, most of which come from burning fossil fuels, are caused by deforestation.
Almost 200 nations are looking into ways to protect forests through a U.N. programme called REDD (Reducing Emissions from Deforestation and forest Degradation) that would put a price on carbon stored in trees in developing nations, for example by bringing forests into carbon trading systems.
Peres said that "degradation" in U.N. jargon referred mainly to logging but should be expanded to cover threats to wildlife. "My mission is to put wildlife and biodiversity into that second 'D' of REDD," he said.
Ah, yes — Homo economicus. If you want to protect forests and the species which live within them, you've got to attach a cost to destroying those forests and species. You could accomplish that by putting a price tag on the carbon those forests sequester. Unfortunately for the tapirs, the large ungulates and the howler monkeys [image above], they don't store much carbon. Few people give a damn about them, so they are subject to endless human predation if you don't explicitly outlaw it.
And when properly prepared, these mammals make for a tasty meal, too.