Monday, October 31, 2011

Tropical rainforests – Age and origin

Tropical rainforests today belong to the areas with the richest biodiversity on our planet. But when and where did these ancients forests came to life? Up to now the generally accepted theory was that these ancient forests originated 65 million years ago at the Equator.

However, according to the latest study by the IRD biologists these forests are in fact much older as they were born around 100 million years ago, and not in the Equator but in the ancient super continental landmass in the Northern Hemisphere. The Equator climate at this time was too hot and dry for humid forests to survive.

The scientists discovered this by using a molecular dating method - based on DNA sequences calibrated with fossils as they constructed a dated phylogeny tracing the origin of existing palm lineages.

It is estimated that tropical rainforests today give habitats to around 50 % of all known species of plants and animals and account for third of our planet's total forests, covering around 7% of our planet's surface.

Why are tropical rainforests so rich with different animal and plant species? The scientists believe that this huge biodiversity is the result of constant diversification due to the continuing existence of this ecosystem since its formation and also at the time of glaciations and massive extinctions they served as refuge zones for many plants and animals.

Tropical rainforests are today under great threat from human activities as deforestation is taking heavy toll in South America, Africa and Asia. Rainforests provide us with valuable resources such as wood, fruit and land reserves so preserving them should be a top priority for world leaders.

Tropical rainforests are also very important in our fight against climate change because they sink huge amounts of carbon dioxide from the atmosphere.