War and civil strife have beset Congo since the African nation’s independence in 1960. That conflict has included two civil wars—in 1996-1997 and 1998-2003—and even now rebel groups continue to plague parts of the country. Millions were killed, and millions more were forced from their homes. These internally displaced persons numbered 3.4 million at their maximum in 2003, but approximately 2.7 million have yet to return due to ongoing violence, mostly in the eastern part of the country.
Some of those people are known to have moved into Congo's forests to escape the violence, and this had severe impacts on the wildlife: Half the gorilla population in the Kahuzi-Biega National Park was killed for bushmeat. There were reports of increased poaching of bonobos and other wildlife. And many animals, including baby primates, were captured for the pet trade.
The extent of deforestation due to this movement of the human population has been unknown. But new analyses of satellite imagery of two protected areas in the north of the country have given researchers a window into this migration. From 1990 to 2000, forest loss—presumably from people clearing pockets deep within the wilderness for farmland—occurred at more than double the rate seen from 2000 to 2010, Janet Nackoney of the University of Maryland College Park and colleagues report in Biological Conservation.
The study examined deforestation in the Luo Scientific Reserve, established in 1992, and the newly created Iyondji Community Bonobo Reserve (ICBR), two areas comprised mostly of lowland rainforest and swamp forest and home to bonobos and many other animals. About 6,500 people live in the Luo reserve, and they’re allowed to hunt animals—though not bonobos or other primates—using traditional methods. They’re also allowed a limited amount of farming on established fields; they can’t clear forest for any new ones, though. Rules for the ICBR, which was set up in 2012, are still being established.
Nackoney and her colleagues compared Landsat images taken of the two reserves in 1990, 2000, 2005 and 2010 (there wasn’t any cloud-free imagery from 1995). To be picked up by the satellite images, any clearings in the forest had to be greater than 30 square meters—about the size of a baseball diamond. They found that the total amount of forest loss over that time wasn’t big, usually less than one percent during each time interval. But as each map was compared with earlier ones, the researchers found increases in the numbers of small, isolated clearings.
These small clearings—rather than vast tracts of denuded land—point to the idea that people who had lived near the reserves moved into the forests when conflict raged. What's more, the rate of primary forest loss declined after the the second civil war ended. And as people returned home after the wars, possibly with larger families, they began to clear forest for new agricultural fields near their old villages, resulting in an increase in forest loss in those areas, the researchers found.
The movement of people in response to conflict had direct effects on the populations of endangered bonobos in the region, according to Nackoney and her colleagues. Researchers have been studying and tracking bonobos in this area since 1973 but were pretty much pushed out during the years of conflict. Those years were devastating for the bonobos—between 1991 and 2005, the number of bonobos in this area declined by more than half, from nearly 250 to about 100, and three groups known to roam the forests disappeared entirely.
Local taboos against eating primates had begun to break down even before the first civil war. It is thought that city-dwellers fleeing political conflict introduced the bonobo-hunting practice when they arrived in the area. During the war, bushmeat hunting thrived. Soldiers pressured villagers to hunt bonobos, and with access to markets cut off, local people had to rely more on bushmeat simply for survival. And it wasn’t just bonobos; elephants, hippos, buffalo and gorillas were also hunted.
The animals aren’t necessarily safe today, though—researchers working on the ground in the two reserves in Congo have reported scattered populations of humans deep in remote forest. Those people moved there during the years of civil conflict and never left, Nackoney and colleagues write.
Tracking something like the hunting of bonobos or small settlements of humans requires people on the ground. Measuring deforestation, though, is lot easier, thanks to satellite images. And it's getting even easier with a new tool for monitoring forests in near real-time and at a resolution of just 30 meters: The World Resources Institute’s Global Forest Watch lets anyone map forest change across the globe. So all Internet users, not just scientists, can watch as big or small patches of trees are cleared, whether it’s for large-scale agriculture, timber production or survival during a war.