# Amazon Jungle Becomes Grasslands-Effect on O2 Production? **URL:** \ **Category:** Factual Questions\ **Created:** [May 24, 2007, 2:27pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346 "2007-05-24T14:27:24Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [May 24, 2007, 2:27pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/1 "2007-05-24T14:27:24Z")
Suppose that due to climate change and development, the Amazon basin changes from a tropical rainforest to a savannah-grassland type environment. Would the replacement of the trees (by grasses) substantially change the oxygen balance of the area? Could such an area support a substantial human population? If the basin were to becokme something like the US grat Plains, would this have any bearing on climate change? ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [May 24, 2007, 2:32pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/2 "2007-05-24T14:32:00Z")
They’d be irrigable and produce one more production but if you had a gemstone on 'em, POOF! It’s gone! ---
**Author:** ![toadspittle](https://avatars.discourse-cdn.com/v4/letter/t/c0e974/32.png) [@toadspittle](https://boards.straightdope.com/u/toadspittle)\ **Post date:** [May 24, 2007, 2:59pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/3 "2007-05-24T14:59:47Z")
Apparently, cutting down more trees–or if there’s another drought this summer–might mean that the whole forest will die. [http://www.nzherald.co.nz/section/2/story.cfm?c\_id=2&objectid=10392615&pnum=0](http://www.nzherald.co.nz/section/2/story.cfm?c_id=2&objectid=10392615&pnum=0) > [@](#): > > Dr Antonio Nobre, of Brazil’s National Institute of Amazonian Research, told the floating symposium of unpublished research which suggests that the felling was drying up the entire forest and helping to cause the hurricanes that have been battering the United States and the Caribbean. > > The hot, wet Amazon, he explained, normally evaporates vast amounts of water, which rise high into the air as if in an invisible chimney, drawing in wet northeast trade winds, which have picked up moisture from the Atlantic. > > This, in turn, controls the temperature of the ocean - as the trade winds pick up the moisture, the warm water left gets saltier and sinks. > > Deforestation disrupts the cycle by weakening the Amazonian evaporation which drives the whole process. > > One result is that the hot water in the Atlantic stays on the surface and fuels the hurricanes. > > Another is that less moisture arrives on the trade winds, intensifying the forest drought. > > … > > Studies by the blue-chip Woods Hole Research Centre, carried out in Amazonia, have concluded that the forest cannot withstand more than two consecutive years of drought without breaking down. > > Scientists say that this would spread drought into the northern hemisphere and could massively accelerate global warming with incalculable consequences. > > The research - carried out by the Massachusetts-based centre in Santarem on the Amazon River - has taken even the scientists conducting it by surprise. > > When Dr Dan Nepstead started the experiment in 2002 - by covering a chunk of rainforest the size of a football pitch with plastic panels to see how it would cope without rain - he surrounded it with sophisticated sensors, expecting to record only minor changes. > > The trees managed the first year of drought without difficulty. In the second year, they sunk their roots deeper to find moisture, but survived. But in year three, they started dying. Beginning with the tallest the trees started to come crashing down, exposing the forest floor to the drying sun. > > By the end of the year the trees had released more than two-thirds of the carbon dioxide they have stored during their lives, helping to act as a break on global warming. Instead they began accelerating the climate change. > > The Amazon now appears to be entering its second successive year of drought, raising the possibility it could start dying next year. The immense forest contains 90 billion tons of carbon, enough in itself to increase the rate of global warming by 50 per cent. > > Nepstead expects “mega-fires” rapidly to sweep across the drying jungle. With the trees gone, the soil will bake in the sun and the rainforest could become desert. > > Deborah Clark from the University of Missouri, one of the world’s top forest ecologists, says research shows “the lock has broken” on the Amazon ecosystem and the Amazon is “headed in a terrible direction”. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 24, 2007, 10:25pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/4 "2007-05-24T22:25:24Z")
[QUOTE=ralph124c] Would the replacement of the trees (by grasses) substantially change the oxygen balance of the area? [/quote] No, impossible. We could kill every tree on the planet and it wouldn’t substantially change the oxygen balance of anywhere at all. Put quite simply forests don’t produce any significant amount of net oxygen. The idea that the Amazon produces oxygen comes from an incorrect teaching of plant physiology that seems to be very widepread in US schools. In a nutshell while trees produce oxygen they also burn exactly as much oxygen. They are not net oxygen producers over any meaningful timescale. > [@](#): > > Could such an area support a substantial human population? Given that rainforests can’t suport humans at all as far as anyone can tell then the answer must be that it woudl suport a far, far higher human population than it does currently. > [@](#): > > If the basin were to becokme something like the US grat Plains, would this have any bearing on climate change? Hard to say, far to many unknowns. One thing we can say is that the massive release of cabron into the atmophere would accelarate the pace of climate change. ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [May 24, 2007, 10:29pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/5 "2007-05-24T22:29:35Z")
[QUOTE=Ludovic] They’d be irrigable and produce one more production but if you had a gemstone on 'em, POOF! It’s gone! [/QUOTE] Thats why you get the engineers involved to make them plains instead grassland. ---
**Author:** ![Dr.Lao](https://avatars.discourse-cdn.com/v4/letter/d/2bfe46/32.png) [@Dr.Lao](https://boards.straightdope.com/u/Dr.Lao)\ **Post date:** [May 24, 2007, 10:38pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/6 "2007-05-24T22:38:03Z")
[QUOTE=Blake] No, impossible. We could kill every tree on the planet and it wouldn’t substantially change the oxygen balance of anywhere at all. Put quite simply forests don’t produce any significant amount of net oxygen. The idea that the Amazon produces oxygen comes from an incorrect teaching of plant physiology that seems to be very widepread in US schools. In a nutshell while trees produce oxygen they also burn exactly as much oxygen. They are not net oxygen producers over any meaningful timescale. [/quote] While I agree that trees are not huge O2 contributors, they do contribute more O2 that they consume. The cellulose in their trunks and branches was made from CO2 through photosynthesis. This carbon is never combined again with O2 by the tree. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 24, 2007, 10:44pm UTC](https://boards.straightdope.com/t/amazon-jungle-becomes-grasslands-effect-on-o2-production/405346/7 "2007-05-24T22:44:56Z")
[QUOTE=Dr. Lao] While I agree that trees are not huge O2 contributors, they do contribute more O2 that they consume. The cellulose in their trunks and branches was made from CO2 through photosynthesis. This carbon is never combined again with O2 by the tree. [/QUOTE] By the tree, not much. By bacteria, and termites, an beetles, and fungi, and elephants, and … In a tropical rainforest the vast majority, as in over 95%, of that carbon in the branches is returned to the atmosphere within 6 months of the tree dying. 99% is returned within a year. Any budget that accounts for the oxygen added to the atmopsphere by the tree has to also account for the oxygen deficit the tree produces by adding reduced carbon to the biosphere. Whether that deficit is repayed by the tree itself or by various consumers and decomposers is of no consequence. The deficit is incurred by the tree and must ultimately be repayed. Hence trees produce no net oxygen. Over any meaningful timesclae they are oxygen neutral.