Geoscience Reference
In-Depth Information
3
Regional Expressions of the
Tropical Rainforest Biome
Three major regional expressions of the Tropical Rainforest Biome are apparent:
the Neotropical, the African, and the Asian-Pacific regions. Distinctions among
them are based on location, origin, climate, soil, forest structure, and species com-
position. They exhibit similarities (and differences) related to geologic, climatic, ev-
olutionary, and ecological events. Some plants and animals found in all regions of
the Tropical Rainforest Biome reflect early origins prior to the breakup of Gond-
wana or a time when rainforests were widely distributed across the continents (see
Chapter 2).
These and other environmental events of the past influenced the differences
seen between the regions. Clearly, the isolation of the regions from one another
provided time and opportunity for species to evolve unique adaptations to their re-
spective environments, as is evident in the flora and fauna of New Guinea and
Northern Australia. Orogenic events, such as mountain building, also isolated spe-
cies and created avenues for further adaptive radiation. Episodes of severe climate
change restricted the distribution of previously widespread species, isolating them
and leading to the evolution of endemic species (restricted to the area of origin).
Each region has elements that make it unique within the Tropical Rainforest
Biome. The Neotropical rainforest is the largest and most extensive, with the high-
est diversity of flora and fauna on the planet. Its long isolation produced endemic
plants and animals uniquely adapted to the Neotropical environment.
The African rainforest is smaller in extent and species diversity than the other
regions. The cooler and drier climate of the Pleistocene Epoch contracted the rain-
forest significantly. This constriction, along with the dominance of single species in
45
