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The rainforest canopy. (Photo by R. Butler)
THE CANOPY
An estimated 70-90 percent of life in the rainforest exists in the trees, above the shaded forest floor. Primary tropical rainforest is vertically divided into at least five layers: the overstory, the canopy, the understory, the shrub layer, and the forest floor. Each layer has its own unique plant and animal species interacting with the ecosystem around them. The overstory refers to the crowns of emergent trees which soar 20-100 feet above the rest of the canopy. The canopy is the dense ceiling of closely spaced trees and their branches, while the understory is the term for more widely spaced, smaller tree species and juvenile individuals that form a broken layer below the canopy. The shrub layer is characterized by shrubby species and juvenile trees that grow only 5-20 feet off the forest floor. The forest floor is the ground layer of the forest made up of the trunks of trees, fungus, and low-growing vegetation. These layers are not always distinct and can vary from forest to forest, but serve as a good model of the vegetative and mechanical structures of the forest.
The overstory is characterized by scattered emergent trees that tower above the rest of the canopy, the tops of some species exceeding 210 feet (65 m). Below the overstory trees, the canopy stretches for vast distances, seemingly unbroken when observed from an airplane. However, despite overlapping tree branches, canopy trees rarely interlock or even touch. Instead they are separated from one another by a few feet. Why the branches of these trees do not touch is still a mystery, but it is thought that it might serve as protection from infestations from tree-eating caterpillars and tree diseases like leaf blight. To survive, canopy dwellers must have the ability to negotiate these gaps by climbing, leaping, gliding, or flying.
The billions of leaves of the canopy, acting as miniature solar panels, provide the source of power for the forest by converting sunlight to energy through photosynthesis. Photosynthesis is the process by which plants convert atmospheric carbon dioxide and water into oxygen and simple sugars. Since the rate of photosynthesis of canopy trees is so high, these plants have a higher yield of fruits, seeds, flowers, and leaves which attract and support a wide diversity of animal life. Besides attracting a broad array of wildlife, the canopy plays an important role in regulating regional and global climate because it is the principal site of the interchange of heat, water vapor, and atmospheric gases. In addition to collecting solar energy and regulating the climate, the canopy shields the understory from harsh and intense sunlight, drying winds, and heavy rainfall, and retains the moisture of the forest below. Thus the forest interior is a far less volatile environment than the upper parts of the canopy ceiling. The interior region is protected from the extremes of the canopy: temperature fluctuations, damaging solar radiation, and strong winds. Light levels are diffuse and subdued, the humidity is higher and more constant, and there is very little direct sunlight in the lower canopy.
Canopy research is key to understanding rainforests
(11/28/2006) Home to perhaps half the world's terrestrial species, rainforests are the most biodiverse ecosystems on the planet. However, when one strolls through the forest, this biodiversity is rarely apparent for the simple reason that most activity in the rainforest occurs in the canopy, a layer of overlapping branches and leaves some 60-120 feet off the ground. Here, a wealth of ecological niches creates opportunities for plants and animals, including species generally considered to be ground-dwellers: crabs, kangaroos, and even earthworms. Beyond housing biodiversity, the canopy is the power source of the rainforest, with billions of tree leaves acting as miniature solar panels to convert sunlight into energy through photosynthesis. Since the rate of photosynthesis of canopy trees is so high, these plants generate higher yields of fruits, seeds, flowers, and leaves which attract and support a wide diversity of animal life. Further, as the principal site of the interchange of heat, water vapor, and atmospheric gases, the canopy also plays an important role in regulating regional and global climate.
Builder of rainforest canopy walkways believes conservation can be profitable
(9/20/2005) This month's issue of The Ecological Finance Review details Greenheart Conservation Company, a for-profit company that designs, builds and operates conservation based canopy walkways (canopy trails) and other nature-based attractions around the world. Operating on the premise that conservation can be economically viable, Greenheart believes that is has already become a "model of how to shift gears from an industrial to a green economy." Greenheart has developed or is developing canopy walkways in Peru, Nigeria, Madagascar, Ghana, Brazil, Guyana, the United Kingdon, and Canada.
Rainforest Canopy - Overstory
(3/1/2005) The overstory consists of giant emergent trees that tower above the surrounding canopy. These trees are huge, at least by tropical standards, some exceeding a height of 213 feet (65 meters) with horizontal limbs that stretch over 100 feet (30 m). These trees live in a different climate from the trees of the canopy. The air is much drier and moderately strong winds blow through their branches. These overstory species have adapted to take advantage of the wind for seed dispersal and typically the seeds of these species are light and equipped with some sort of mechanism to allow the winds to carry the seeds great distances away from the parent tree. The Kapok (Ceiba), or Silk-cotton tree, of South America releases its seeds attached to cotton-like material, which drifts in the wind currents for miles before reaching earth. Before fruiting, the tree sheds all its leaves so breezes pass unimpeded through its branches. In Asia, the seeds of emergent tree species Dipterocarps are equipped with "wings" that cause the spinning seed to slow as it falls and enable it to be carried long distances by the breeze..
Rainforest Canopy - Research & Study
(3/1/2005) Little was known about this rich layer until relatively recently when scientists discovered efficient ways to study the canopy. However, even with modern techniques of study, many species, systems, and relationships of the canopy are still mysterious and much is still left to be discovered.
Rainforest Canopy - Introduction
(3/1/2005) An estimated 70-90 percent of life in the rainforest exists in the trees, above the shaded forest floor. Primary tropical rainforest is vertically divided into at least five layers: the overstory, the canopy, the understory, the shrub layer, and the forest floor. Each layer has its own unique plant and animal species interacting with the ecosystem around them. The overstory refers to the crowns of emergent trees which soar 20-100 feet above the rest of the canopy. The canopy is the dense ceiling of closely spaced trees and their branches, while the understory is the term for more widely spaced, smaller tree species and juvenile individuals that form a broken layer below the canopy. The shrub layer is characterized by shrubby species and juvenile trees that grow only 5-20 feet off the forest floor. The forest floor is the ground layer of the forest made up of the trunks of trees, fungus, and low-growing vegetation. These layers are not always distinct and can vary from forest to forest, but serve as a good model of the vegetative and mechanical structures of the forest.
