The canopy system characteristic of tropical rainforests
further increases diversity by creating new niches in the form of new
sources of food, new shelters, new hiding places, and new areas for
interaction with other species. In fact, it is estimated that 70-90
percent of life in the rainforest is found in the
trees. One of the best examples of a canopy niche which multiplies diversity
are the epiphytes, many of which form tiny ecosystems of their own.
The tank bromeliads of New World forests can hold over eight liters
(two gallons) of water in catchments formed in their stiff, upturned
leaves. These pools of water serve as nurseries for frog tadpoles and
insect larvae specifically adapted to life in this tiny obscure niche,
and provide water for millions of other canopy dwellers. Over 28,000
epiphyte species are known to science, although many more have never
been catalogued.
In addition to epiphytes, other plant species including lianas and creepers,
create new means for ground-dwelling animals to access the resources
of the canopy. Many of the ground-dwelling animals of the temperate
zone, like porcupines, kangaroos, anteaters, earthworms, and crabs,
have moved up into the canopy in tropical regions.
Rainforest canopy in Borneo. (Photo by R. Butler)
Review questions:
How does the canopy amplify rainforest biodiversity?
How does area impact biodiversity?
Does forest fragmentation reduce forest diversity?