All tropical
rainforests are located in a narrow belt that girdles
the earth's equator. This belt is known as the
"tropics." In the tropics, constant sunlight, rain and
high temperatures spell year-round life -- making the
rainforests rich in a wide variety of plant and animal
species. In fact, tropical rainforests contain over
half of all the living things known to man.
photo M. Noonan
In the
Eastern United States we have temperate forests. In
these forests, plants bud and bloom in the spring and
summer, when temperatures are warm and sunlight is
available. Then, in the fall and winter, temperate
trees drop their leaves and go dormant for the harsh
winter months. This leaf litter builds up on the forest
floor, creating a stockpile of nutrients in the
temperate soil.
In contrast,
the tropical rainforest lacks such a seasonal cycle.
Here, sunlight, rain, and warm temperatures are fairly
constant, meaning that plants germinate, grow, flower
and seed year-round. These warm temperatures ensure
that decomposition of dead leaves and other waste
material occurs at a rapid pace in the tropics. Thus,
the ecosystem of the rainforest has most of its
nutrients stored overhead in the leafy canopy rather
than underfoot in the soil, as it is in the temperate
regions of the globe.