Environmental Relationships in
Tropical Rainforests
Climate: Tropical
Wet (Af)
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High rainfall all year (>2” / month)
Straddles Equator by 5o - 10o
Windward mountain regions in tropics
Consistently warm (all months > 18ºC/64.4ºF)
Annual precipitation exceeds evaporation
Daily temp range exceeds annual temp range
Cook Islands, 2001
Costa Rica, June 2004
Costa Rica, June 2004
Fiji, 2004
OVERVIEW: TROPICAL RAINFOREST ENVIRONMENTS
Where: Straddles Equator by 5o - 10o. Northern South America, Central America,
West and Central Equatorial Africa, SE Asia, NW Coastal Australia, Pacific Islands.
Covers 6% of land surface (down from 14% prior to humanity).
Vegetation: Tens of thousands of species. Highest density of species, tall
trees, many canopy layers, evergreen, broadleaf trees, epiphytes, lianas (vines),
climbers, stranglers, ferns.
Fauna: More species than all other biomes combined, colorful insects,
amphibians, reptiles, and birds, few large animals, high density of biomass and
incredible species diversity.
Soils: Laterite, thin and poor, most nutrients in vegetative litter because of
leaching, biological processes, and rapid weathering. Red or orange soils.
Threats: Among most threatened biomes. Logging and various types of
deforestation, mining, cattle ranching, and development all contribute to an
estimated loss of 214 acres a day (larger than New York City).
Tropical Rainforest Vegetation:
Broadleaf Evergreen
Deciduous vs. Evergreen
• Cold
• Low Sunlight
• Drought
Broadleaf vs. Needle-Leaf
• Abundance of Water
• Cold
Lianas (Vines)
Epiphyte
Epiphyte
Buttresses
3-Toed Sloth, Panama
Clear-cut Tropical Deforestation
Strangler
Fig
Slash-and-Burn
Agriculture
Leaf-cutter Ants,
Costa Rica
Tropical Soils:
Laterization
Ironically, tropical areas have
poor soils. High temperatures
and very high rainfall lead to
the characteristically red soils
of tropical areas.
Sugar Cane Field, Maui
Most minerals are dissolved
and leached away out of
reach of plants. The
remaining minerals (iron,
aluminum, and manganese)
are highly oxidized (rusted)
and appear red. Only a very
thin top layer of soil is rich.
Laterite
Soil, Fiji
Summary: Tropical Rainforest
Where: Straddles Equator by 5o - 10o. Northern South
America, Central America, West and Central Equatorial Africa, SE
Asia, NW Coastal Australia, Pacific Islands. Covers 6% of land
surface (down from 14% prior to humanity).
– Vegetation: Tens of thousands of species; highest
density of species, tall trees, many canopy layers, evergreen,
broadleaf trees, epiphytes, lianas (vines), climbers,
stranglers, ferns.
– Fauna: More species than all other biomes
combined; colorful insects, amphibians, reptiles, and birds,
few large animals, high density of biomass and incredible
species diversity.
– Soil: Laterite; fairly thin and poor, most nutrients in
vegetative litter because of leaching, biological processes,
and rapid weathering.
– Threats: Among most threatened biomes; logging and
various types of deforestation, mining, cattle ranching, and
development all contribute to the loss of 214 acres a day
(larger than New York City).
Remember:
Geographers
Do Fieldwork!
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Global Rates of Rainforest Destruction (including deforestation)
2.4 acres (1 hectare) per second: equivalent to two U.S. football fields
149 acres (60 hectares) per minute
214,000 acres (86,000 hectares) per day: an area larger than New York City
78 million acres (31 million hectares) per year: an area larger than Poland
Source: Myers, Norman. 1989. Deforestation Rates in Tropical Forests and Their Climatic Implications. Updated 1994.