i also have always thought trees provide oxygen and hece just looked it up and found among many othere things: "A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings." - McAliney, Mike. Arguments for Land Conservation: Documentation and Information Sources for Land Resources Protection, Trust for Public Land, Sacramento, CA, December, 1993 "On average, one tree produces nearly 260 pounds of oxygen each year. Two mature trees can provide enough oxygen for a family of four." - Canada's environmental agency, Environment Canada there must be an xplanation. robin carrier ----- Original Message ----- From: "lou jost" <loujost@yahoo.com> To: <pbs@lists.ibiblio.org> Sent: Tuesday, December 27, 2011 1:27 PM Subject: Re: [pbs] conservation of habitats (rain forest) 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 http://www.loujost.com/ http://www.ecominga.com/