conservation of habitats (rain forest)

lou jost
Tue, 27 Dec 2011 10:27:36 PST
Peter, while forests are really important for regulating the water cycle and storing carbon, they have virtually nothing to do with oxygen generation or regulation. The idea that forests are the "lungs of the earth" or "make our oxygen" is a myth. Forests are approximately oxygen-neutral. They are also almost carbon-neutral, but they do have a vast store of standing carbon (accumulated over a long timespan) at any moment. This carbon is all released into the atmosphere when the forest is burned.

On the other hand, forests' role in water regulation is under-appreciated. A large fraction of the water that falls as rain in Amazonia has been recycled through trees multiple times, so western Amazonia would  get much less rainfall if the Amazonian rain forest were reduced. Trees reduce runoff; if the trees were not there, water would go quickly and directly into rivers and then to the ocean, rather than being taken up by the vegetation and transpired. This also makes for more stable rivers that flood less often and do not dry up as often. Also, in cloud forests, water condensing or collecting on tree leaves is an important source of "rain"; this rain only falls inside the forest. This kind of "rain" keeps many rivers alive during dry seasons, and many cities depend on such streams. The streams would disappear without the forest.
Lou Jost

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