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Film summary
Tropical rainforests are competitive environments where plants must compete for space and resources. But other dangers threaten the balance and future of these important habitats.Key facts
- Tropical rainforests cover only 6% of the globe.
- However, they are home to over half of all species.
- Trees absorb water and release the excess as vapor, which rains back down.
- Due to man's destruction, rainforests are under serious threat.
Transcript
Tropical rainforest covers just 6% of the globe, yet they are home to half of all species on Earth.
Tropical rainforests are found just south of the equator in Africa and Asia.
Tropical rainforest:
6% of Earth's land
Most biodiverse habitat on Earth
The world's largest rainforest is the Amazon, in South America, spanning nine countries and 4 million km2.
The Amazon rainforest:
South America
4 million km2
The sheer size of these rainforests means they create their own climate through a process called transpiration.
Transpiration
The trees absorb more water than they use, so some is released back into the atmosphere as mist.
The mist gathers into clouds, which then move across the jungle and release their moisture as rain.
On average, a rainforest receives a staggering two meters of rain a year, half of it created by the trees.
Too much water can be a problem for plants, so many have waxy leaves with drip tips to drain excess water.
Tropical rainforest climate:
High sunlight
2m annual precipitation
Despite 12 hours of daylight year round, the thick canopy of a rainforest allows only 2% of sunlight to reach the forest floor, making it difficult for seedlings to grow.
So when an older tree falls the race for a spot in the canopy is on.
Macaranga plants
Macaranga plants can grow 8m a year.
Hardwood trees
Hardwood trees grow to 50m.
Liana vines
And liana vines can be over 900m long, creating highways for insects and animals between the trees.
Rainforests are a vital habitat, sustaining diverse ecosystems.
But these remarkable forests are under serious threat.
In the last 40 years, 20% of the Amazon has been destroyed for human gain.
If destruction continues unchecked, there are fears that by 2020 the overwhelming majority of pristine Amazon rainforest will be lost forever.
