Environmental Relationships in Tropical

Rainforests

Climate: Tropical Wet

(Af)• 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

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).

OVERVIEW: TROPICAL RAINFOREST ENVIRONMENTS

Tropical Rainforest Vegetation: Broadleaf

EvergreenDeciduous vs. Evergreen

Broadleaf vs. Needle-Leaf

• Cold

• Low Sunlight

• Drought

• Abundance of Water

• Cold

Buttresses

Epiphyte

Lianas (Vines)

Epiphyte

Strangler Fig

3-Toed Sloth, Panama Clear-cut Tropical Deforestation

Slash-and-Burn Agriculture

Leaf-cutter Ants, Costa Rica

Sugar Cane Field, Maui

Tropical Soils: Laterization

Laterite Soil,

Fiji

Ironically, tropical areas have poor soils. High temperatures and very high rainfall lead to the characteristically red soils of tropical areas.

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.

Summary: Tropical RainforestWhere: 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!

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.