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Week of 15 January 1999 Vol. II, No. 19 Feature Article A classroom in the wild Treetop walkway gives bird's-eye view of rain forest diversity By Hope Green At the Tiputini field station in Ecuador, CAS Biology Professor Thomas Kunz pauses on the new elevated observation path, which BU constructed last August. It spans the length of a football field and allows students and scientists access to the forest's high branches. Photo by Philip Wittman Much of what happens in the rain forest escapes the human eye. A dozen scarlet macaws in flight, a leaf-nosed bat sucking nectar from a white Parkia blossom, a strangler fig seed sprouting a cascade of air roots from atop its lofty host plant -- all are obscured in a tangle of tree boughs 100 feet up. But deep in the Amazon, BU undergraduates who study tropical ecology have gained an enviable perch for viewing arboreal activity. At the Tiputini Biodiversity Station, in the Oriente region of Ecuador, the University's Center for Ecology and Conservation Biology (CECB) has installed an elevated walkway that weaves above and through rain forest branches at the height of a 10-story building. An observation tower was erected on the property two years ago, but the narrow walkway, which spans 600 horizontal feet, widens the opportunity for researchers to examine the forest's teeming canopy. "It's comparable to being able to swim through a stratum of the ocean rather than just being able to look at the surface," explains Thomas Kunz, CAS biology professor and CECB director. "The walkway allows biologists access to one of the last unexplored areas of rain forest." According to Kunz, the new $85,000 structure is connected by stainless steel cables to five tall-growing trees that emerge above canopy level. Unlike the old wooden models, of which there are about 30 worldwide, this one has treads and platforms constructed of Polywood, a patented recycled-plastic material that resists natural corrosion. Pedestrians on the undulating 20-inch-wide treads are protected by durable synthetic straps and safety nets. Among the first human footsteps on the walkway were those of six juniors and two seniors from BU who completed the fall Tropical Ecology Program. "It was a little frightening going up," admits Amanda Cooper (CAS'00), "because you're on a ladder that's attached to a tree and it's a very vertical ascent. But once you get up there you're in a whole other realm. We could see for miles. Every tree is different from the last one, and the epiphytes growing on them vary greatly also." Using the elevated footpath, Cooper and classmate Peter Frye (CAS'00) took an inventory of epiphytes such as orchids, ferns, and bromeliads (hanging moss). "The walkway gives you a large sample size because it covers such a wide area," Cooper says. The semester-long 18-credit program, which began in 1995, is jointly run by the Division of International Programs and the CECB in collaboration with the Universidad San Francisco de Quito (USFQ) in Ecuador. It is open to upperclassmen majoring in biology or environmental science who have earned a grade point average of at least 3.0. Besides their work at Tiputini, students conduct field studies in the mountains, on the Pacific coast at Los Piqueros, and on the Galapagos Islands. During the semester's first and last months, participants study Spanish, Ecuadoran culture, and tropical ecology at USFQ and are housed with local families. Students are applying to participate in increasing numbers, "which is good," says Kunz, "because it allows us to be selective." A group of 24 will fly to Ecuador this month for the spring term. The program's rain forest segment consists of four weeks in the 1,600-acre Tiputini Biodiversity Station, in what Kunz calls one of the world's last unspoiled tropical forest regions. Golden-mantled pygmy marmosets, armadillos, peccaries, and howler monkeys are some of the larger creatures students have reported sighting. Hundreds of other animal varieties (including an estimated 500 different birds) and multitudes of insect, fungus, and plant species make up the indigenous food chain. This wild laboratory, Kunz says, motivates undergraduates to raise questions and test their own hypotheses. One student last spring, for instance, studied a particular vine to determine which type of tree it prefers and why. Factors to review in that case included tree height, trunk diameter, and bark surface. "In the natural environment," says Kunz, "the biggest problem is to design an experiment in which you minimize the number of variables. It's not as simple in the wild as it is in the laboratory, but on the other hand, the lab experiment tends to be biased because the real world functions in a multifactorial way. So by exposing students to these kinds of questions, we're preparing them intellectually for the complexity they must face in the future." A view from ground level of the 10-story-high canopy walk, which is reached by ladder and stretches across the boughs of five trees, at the Tiputini Biodiversity Station. Photo by Thomas Kunz It is estimated that 70 percent of the world's flora and fauna live in the tropics, and half of tropical organisms live up in the rain forest canopy. The walkway will put more of them within the grasp of scientists. For starters, two graduate students will use the structure for research on bats this month under the direction of Kunz, a renowned specialist on the winged mammals. One study will compare the foraging behavior of three omnivorous bat species in a pristine habitat versus a disturbed one. Another project focuses on male tent-making bats, which attract females into enclosures they have delicately constructed from leaves. Using DNA probes, the researchers will examine the genetic population structure to determine whether one male sires all the offspring raised in his tent. "Studying animal and plant life at a pristine site like this one allows us to establish baseline information on the dynamics of the rain forest," Kunz says. "This helps us to better manage other areas that we're also trying to protect and preserve." Kunz likens the Tiputini walkway to the early microscopes that revealed previously unseen life forms in a drop of water. "There are so many organisms in the tropics that have never been described or discovered," he says. "And there are probably tens of thousands of insect species in the canopy of the rain forest that we don't even know exist. People tend to worry about the soft and cuddly and the mega-charismatic organisms like the big redwoods, rhinos, and giant pandas. These are important and are vehicles for us to appreciate and protect other areas, but those little inconspicuous insects are also important, because they play key roles in maintaining an ecological balance." Kunz has taught at BU since 1971. BU Adjunct Associate Professor Kelly Swing, who also holds a faculty title at USFQ, directs the Tiputini Biodiversity Station and supervises undergraduates there each semester. BU has just hired an additional instructor, Monica Swartz, to assist the students this spring. Eventually, Kunz hopes to add a 300-foot extension to the walkway, install solar power at the field station, and add a satellite link for Internet access. At the moment, though, his priority is to establish scholarship and fellowship programs in tropical ecology. "Any kind of quality educational program requires an underlying strong emphasis on research," he says.