Studying the rainforest canopy
Learning about the richest region of the forest
Crane’s Eye View
Tina Butler, mongabay.com
April 21, 2005
A groundbreaking new project dedicated to studying rainforest canopies is about to enter the implementation stage in five tropical forests across the globe. The Global Canopy Programme, headed by Dr. Andrew Mitchell of Oxford University, consists of the placement of giant cranes in Brazil, Ghana, India, Madagascar and Malaysia. The cranes, outfitted with observation platforms and laboratories, will swing exploratory arms freely out over the top of the canopy with enough clearance to avoid disturbing the environment or its inhabitants. The 17 million-dollar project is not the first of its kind—similar projects have been installed in Panama among other locales—but the program is notable for its scale. Ten cranes under the same program are already in use in temperate forests, but the real mystery lies still in the tropical rainforests, specifically in the canopy.
While study of these regions has been increasing and evolving, the rainforest canopy remains relatively uncharted territory. The gap in knowledge may be accounted for due to the problem of access, but closing this gap is crucial in improving scientists’ understanding of rainforest functioning as a whole as well as gaining insight on particular processes such as pollination and symbiotic relationships in this forest level. The canopy is indisputably the richest region of the forest; an estimated 40% of all terrestrial species are found at a height of 20 meters and higher, the canopy level being situated at this height in most forests. Dr. Mitchell himself asserts that 80% of insects recovered from the canopy are new species. Generally 70-90% of life in the rainforest exists in the trees and the canopy accommodates the highest density of life. Clearly, the potential for new and meaningful discovery is profound.
The canopy’s basic makeup is central to its burdensome role as provider and protector in the forest. Essentially a dense ceiling of closely spaced trees and their branches, this forest level is a zone of high-energy absorption and production. Photosynthesis occurs at a very rapid rate as the billions of leaves concentrated in the one area act as miniature solar panels. This massive energy exchange results in greater fruit, seed, flower and leaf yields than any other part of the forest, therefore attracting and supporting a wide variety of animal life. The canopy performs an invaluable function in regulating the climate, on both a regional and global scale, because it is the primary site of the interchange of heat, water vapor and atmospheric gases. Acting simultaneously as a shield, insulator and energy producer among other things, the canopy plays the most essential and irreplaceable role in the forest. And yet there is still so much that remains unknown.
One of the main unanswered questions posed by the creators of the Global Canopy Programme is whether the canopy functions as a sink for or a source of carbon. Given the growing focus on global warming and its influences on climate and subsequent general well being of Earth’s living things, this is one of the major issues the project hopes to shed light on. The primary reason such a weighty question like this persists is due to the problem of access to the canopy level. Scientists have been studying the rainforest for decades, but getting to the crucial area of the forest has proved to be an elusive and troublesome endeavor.
Some early techniques for studying the canopy level ranged from the destructive to the deranged to the divine, including the felling of whole trees, shooting down branches with shotguns, hiring natives to climb trees, and firing ropes up into the trees for climbing. One scientist in Borneo devised a low-impact, non-intrusive, but ultimately limiting method that consisted of a monkey trained to retrieve certain plant species from the upper levels of the forest. All of these techniques, regardless of their imaginative, aggressive or downright foolish qualities, resulted in an incomplete collection of information, revealing little about the exotic and still compelling area.
In the 1970s, advances were made in the methods for accessing the canopy by employing mountaineering techniques with ropes and the building of platforms for extended observation-based study. Despite major improvements upon earlier techniques, the small, stationary yet expensive platforms offered only a narrow range of observation and the use of ropes was often dangerous. More modern methods of access have included the use of ultra-lite planes, blimps, ski lift-like trams and remote controlled pulley systems. One other innovative experiment involved balloon rafts, placed on top of rainforests in West Africa and French Guyana. While this method afforded greater access on a more long-term basis, the projects were very costly and the weight of the rafts resulted in damage to the canopy.
Canopy walkways are currently one of the most popular and practical modes for reaching this forest level. Large areas of forest, connected by a network of swinging bridges, are now accessible and the walkways have the added benefit of having little negative impact on rainforest habitats and rhythms. The only real threat inherent in these walkways is overuse, not likely by scientists, but by tourists who are visiting the rainforests in increasing numbers and frequency. The cost of building and maintaining the walkways is often recovered by the profits from ecotourism. There is always room for improvement however, and the Global Canopy Programme aspires to be the next big thing.
The unique benefits of the cranes are clear, but there are certain issues that remain problematic. While the cranes will rotate a safe distance above the canopy top, for airborne animals like bats and birds, (which are extraordinarily plentiful in the rainforest), one wonders what effect these new, large foreign bodies will have on the natural existence and movement patterns of resident animals. There is also the question of noise and heat emitted by the cranes in terms of movement and from generators powering the labs and how that will impact the organisms and their environment. Finally, while the cranes will be helicoptered into the forest in pieces, the process of construction and erection of the machines will undoubtedly cause some inevitable damage. These issues aside, the Global Canopy Project looks to be the most revolutionary project on the horizon for canopy study. Hopefully, the information collected over the coming years will proffer new insight on this fugitive frontier.
The Rainforest Canopy