Geoscience Reference
In-Depth Information
Figure 2.6 Forest structure of a lowland rainforest in the Neotropics and Asian-Pacific.
The forest structure of African rainforest is similar but trees tend to be smaller. (Illustra-
tion by Jeff Dixon. Adapted from Lambertini 2000.)
of the forest canopy passes to this layer. Suppressed growth is characteristic of the
young trees that inhabit this zone, although they are capable of a rapid surge of
growth when a gap in the canopy opens above them. Shrubs that can grow in low
light are found in this layer, many having large leaves to catch whatever light is
available.
Little grows on the forest floor. Less than 1 percent of the light that strikes the
top of the forest penetrates to the forest floor. In this shade, few green plants can
grow. Moisture is also reduced by the canopy above: one-third of the precipitation
is intercepted before it reaches the ground. The layer is composed of a few ferns
and herbaceous plants, but mostly dead, decaying plants and animals and the
organisms that decompose them (see Figure 2.7).
As the layers of vegetation in the canopy are varied, so too are the habitats they
provide for other organisms. Each layer has a unique set of lifeforms and lifestyles
of organisms that have adapted to the specific resources available to them.
Common Characteristics of Tropical Trees
Trees in the Tropical Rainforest Biome are often different from trees found at other
latitudes, yet are similar throughout the tropical forest regions of the world. Some
of the common characteristics include smooth bark or bark with spines or spikes,
buttressed trunks, large leaves, and leaves with drip tips. In addition to similar tree
characteristics, the tropical rainforests of the world contain climbing woody plants
in the form of vines or lianas.
Buttresses. Many emergent trees found in the Tropical Rainforest have broad,
woody flanges at the base of the trunk. These buttresses were originally believed to
help support trees with a shallow network of roots, adding support in wet soils.
Recently it has been shown that these buttresses also take part in carbon dioxide
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