Forest fragmentation has been a major concern of conservationists for many years, with vast sections of forest being cut away for logging, farming, ranching, and development leaving smaller and smaller fragments of forest habitat. Earthwatch supported research has raised awareness about deforestation and forest conservation among both scientific and local communities. Facing the reality that many forest areas cannot be restored in their entirety, Earthwatch-supported scientists have explored ecological processes in forest fragments and how to best manage fragments for optimal biodiversity.
In the 1990's, Dr. William Newmark (Utah Museum of Natural History) gained Earthwatch support for the longest continuous study of any tropical bird community in a fragmented landscape, the rich forests of the Usambara Mountains, Tanzania. Newmark had earlier shocked wildlife managers in the United States when he discovered that Yellowstone National Park was too small and isolated a fragment to sustain signature species like grizzly bears. Newmark's work in Tanzania was one of the first demonstrations of metapopulation dynamics in any tropical community. Earthwatch teams working with Newmark have discovered that most understory bird species will not cross gaps in the forest wider than one kilometer. Newmark's work has led to the creation of wildlife corridors to link the Usambara Mountains to remaining large blocks of forest as part of the East Usambara Forest Area Management Project. A major grant from the MacArthur Foundation is supporting a broader biodiversity study by Tanzanian researchers under Newmark's leadership (see Legacy of Learning).
"Earthwatch support and the help of Earthwatch volunteers have been central to the achievement of my research objectives," said Newmark, principal investigator of Tanzanian Forest Birds. "It would not have been possible to conduct this research for the length of time that I have without Earthwatch support."
In the highly fragmented Atlantic Forest of Brazil, where less than 10 percent of the forest remains, Earthwatch teams helped Alexine Keuroghlian (University of Nevada, Reno) find that white-lipped peccaries survived in small fragments if habitat diversity and keystone fruits were available. Foraging outside forest reserves for seasonal fruits was also important. Another Atlantic Forest study by Dr. Athayde Tonhasca (Universidade Estadual do Norte Fluminense) and colleagues evaluated the ecological importance of forest fragments in the buffer area of the proposed Desengano State Park, Brazil. By monitoring the movements of euglossine bees, important pollinators of forest plants, Earthwatch teams were able show that forest fragments may recover functional orchid populations once disruptive actions such as fire and logging are halted. These findings were helpful in determining the ecological importance of forest fragments.
A landmark study was conducted by Dr. Alejandro Estrada (Universidad Nacional Autonoma de Mexico) and Rosario Coates-Estrada (Los Tuxtlas Biological Station) in the rainforest of northern Mexico. With help from over 200 Earthwatch volunteers, these researchers sought to examine the effect of rapid deforestation on biodiversity. In a region where only 15 percent of the original rainforest remained, Earthwatch teams surveyed 92 sites in a variety of habitats to sample 16,000 birds and mammals, representing 340 species. They found 80 percent of the species in small forest fragments, suggesting that these fragments can harbor more species than originally thought. In some cases, farmlands that had replaced forests were actually serving as corridors for species to travel from one fragment to another. The Estradas' research revealed that many of the crops that provided successful links between fragments were also valuable export crops like coffee, cacao, mangos and citrus fruits.
"The work of Earthwatch teams verified that-far from being worthless-small forest patches, in concert with certain croplands and plantations, show tremendous potential as refuges for rainforest wildlife," said Estrada. "Maybe they will be able to protect only one out of every fifty forest fragments, but at least we can tell them which fragments are most important and how best to manage the rest." The Estradas' work led to the Mexican government decreeing the region of Los Tuxtlas as a biosphere reserve, effectively halting deforestation in the area.
More recently, Drs. David Westcott and Andrew Dennis (both of CSIRO Tropical Forest Research Center) have studied the behavior and movements of seed-dispersing animals in continuous rainforest and rainforest fragments in Queensland, Australia. Working as part of Earthwatch's Australian Conservation Research Initiative, volunteers in the Wet Tropics World Heritage Area are using radiotelemetry and direct observation to monitor everything from cassowaries to golden bowerbirds to musky rat-kangaroos. They have collected enough data on 17 species to begin building models of seed dispersal for each, helping to predict how species decline may influence forest dynamics fundamental to biodiversity.
"Our greatest achievement with the help of Earthwatch volunteers has been the steady accumulation of very large sets of data," said Dennis, principal investigator of Rainforests of Northern Australia. "It's the sort of thing that we would not be able to achieve on our own, because collecting this kind of data takes an enormous amount of time."