The Office of
307 Bynum Hall
Campus Box 4106
UNC-Chapel Hill
Chapel Hill, NC 27599-4106
Tel: (919) 962-6136
Invasive plants and animals once foreign to the famous archipelago are eroding fragile landscapes and threatening species that have been aiding scientific discovery since Charles Darwin’s first voyage in 1835. The Ecuadorian government knows this, as do other local organizations and the United Nations, which is considering listing the archipelago as a World Heritage Site at risk. That’s why Ecuador’s ministry of the environment asked Steve Walsh, geographer and fellow at the Carolina Population Center, to help map the problem and form a team to find solutions.
Since 1997, Walsh has been studying changes in land use and land cover in the Ecuadorian Amazon Forest. The ministry wondered if Walsh’s satellite technology and high-resolution imaging could pinpoint invasive species in the Galapagos. So last February Walsh’s team mapped the spatial patterns of selected invasive plants and used satellite data to build digital elevation models to map three dimensional landforms and landscapes. One of his maps shows how guava fruit trees, which were brought in by humans long ago, spread so fast that grasslands are changing into forests. Before that, no one could show the pattern of how guava had been spreading.
But beyond making maps and models, Walsh is putting together a team to tackle the larger issue of human involvement that dates back to Darwin’s time.
The Galapagos remained unsullied by humans for millions of years until whalers, sealers, and even pirates put goats and pigs on the islands as food sources for return visits. The animals thrived, in part by eating guava, whose seeds traverse animal digestive tracts intact. Thanks to the natural fertilizer and the increase in animal populations, guava trees began sprouting like weeds. They germinated densely, creating a canopied forest where grasslands had been.
“Now such plants are overtaking indigenous plants that appear no place on Earth other than in the shadows of volcanoes,” Walsh says. “There are entire landscapes overcome by invasive species. It is a dramatic problem.”
Eradicating some invasive species might be a result of Walsh’s maps, but his goal is much broader.
“It’s about trying to understand how the human dimension connects with the environment,” he says.
Thirty thousand people live on the Galapagos, and about 125,000 tourists visit annually. There are hotels, restaurants, two airports, farms and plans for further development.
Walsh returned to the archipelago this summer with sociologist Ron Rindfuss, anthropologist Flora Lu Holt, Carolina students Carlos Mena, Amy McCleary, Julie Tuttle and Patricia Polo, and two colleagues from other universities. They validated Walsh’s preliminary maps, gave workshops on spatial digital technology, and held meetings about Carolina becoming a longstanding research partner with the Charles Darwin Research Center, the Galapagos National Park, and Ecuador’s Ministry of the Environment to study and help ecological systems under stress.
Walsh will return to the Galapagos this fall to present his team’s preliminary research at a public forum.
Provided by Research and Economic Development.
Editor: Neil Caudle
Writer: Mark Derewicz