Tropical Rain Forest
Tropical rain forests, sometimes colloquially called "jungles", are the most rainy and humid areas on the Earth. These biomes are areas of high diversity, and only cover about 6% of globe's surface. Plants tend to have adaptations to survive frequent rainfall and poor soils.
Types
Moist seasonal tropical forest: high rainfall during summer; cooler dry winter
Montane rainforests: areas between 1,500 - 3,000 m above sea level
Flooded rainforests: found in the Amazon basin
Climate
Rainfall
More than 200 cm/yr (up to 1,150cm/yr)
Mawsynram India, the wettest place, receives 11.9 meters (or 39 feet) of precipitation per year
Temperature
Year-round warmth
Tropical rain forests are almost always between 19 - 28°C
Above: A Whittaker Graph showing where tropical rainforests occupy this abiotic space, based on precipitation and temperature
Soils
Soils are very poor in rain forests due to leaching by rainfall
Oxisols: highly weathered tropical and subtropical soils
Regional Expressions
South America; west Africa; southeast Asia
Flora
High diversity; species spaced apart
Evergreen trees with four layers of vegetation
Emergent
Canopy
Under-story
Forest floor
Plant Adaptations
Drip tips, waxy leaves
Buttress roots and Prop roots
Large showy flowers to aid in pollination
Shade-adapted and large leaves in under story plants
Lianas and vines
Epiphytic habit
Water storage stems in forests cacti
Velamen on roots in orchids
Cup-like rosette of leaves in bromeliads
Above: Buttress roots
Above: Prop roots
Evolution of the biome
Tropical rainforests, areas of high rainfall near the equator, existed on Earth since the Carboniferous Period (over 300 million years ago)
The Coal Age was a time in which much of the Earth was warm and tropical, and vast swamps with scale trees, tree ferns, and tree-sized horsetails
These Paleozoic rainforests would have looked much different from modern jungles, with different groups represented and a canopy that was more open
Over geologic time, rainforests have expanded and shrunk with changes in the climate
Tropical Rain Forests.pdf