BBC News science correspondent David Shukman has been looking at the effects of deforestation on Borneo's rainforests.
The towering habitats play host to a diverse range of species and are also responsible for absorbing huge amounts of the greenhouse gas carbon dioxide. Scientists believe that protecting them will play a vital in curbing climate change.
As he inches his way down one of the rainforest's vast trees, David offers an insight into the layers that make up this vibrant ecosystem.
The tops of the rainforest's very tallest trees - some reaching heights of more than 60m (200ft) - make up what scientists describe as the emergent layer.
Towering above the ground below, the trees withstand weather extremes, including searing heat, strong winds and fierce rain storms.
Despite this, many animals make these heady heights their home, including eagles, gliders, bats and butterflies.
A ceiling of densely packed foliage, jostling to catch as much sunlight as possible, forms the rainforest's canopy layer.
Loaded with fruit and seeds, the canopy provides a rich food source for the huge number of species that dwell there, including insects, primates, bats and birds.
Because trapped rainwater continuously evaporates from this layer, the canopy impacts upon local and global weather.
Little sunlight makes its way through to the understorey layer, where insects dominate.
Here, juvenile trees wait - often for years and years - for a taller tree to fall and leave a break in the canopy that will let in the light that they need to grow.
This layer is also key to the climate - tree trunks hold massive amounts of carbon dioxide, but if the trees are felled and burnt, this gas is released back into the atmosphere.
The dark, humid forest floor is home to detrivores - animals such as microbes, fungi and insects that feast on rotting organic material.
As the creatures break down the dead leaves and branches, nutrients are released back into the soil to be soaked again up by the enormous root systems of the vast trees.
Other larger animals live here too, such as orangutans.