Scientists Discover Link Between Trees and Electricity 173
An anonymous reader writes "Everyone knows trees give us all oxygen so we can breathe, but according to Australian scientists, they also affect the concentration of positive and negative ions in the air. A team from the Queensland University of Technology's International Laboratory for Air Quality and Health ran experiments in six locations all over Brisbane and found that positive and negative ion concentrations in the air were two times higher in heavily wooded areas than in open grassy areas, such as parks."
Re:Seems kind of obvious that this should be true (Score:5, Informative)
This has been known (Score:5, Informative)
This has been known for a very long time and it's very much common knowledge. Ambient negative ion levels can even be obtained through weather services in my country. My Daikin air conditioner even claims to keep ambient ion levels at "lush forest" levels and it's not near new. Just do a google search for "forest negative ion" and you'll find tons of products and articles on the subject. Why is this at all news?
This is cooler (Score:4, Informative)
http://www.livescience.com/5711-electricity-harvested-trees.html
Trees actually produce a small current when a nail is inserted into them and connected to a ground. It is not via the same mechanism as a battery.
Re:And yet. (Score:5, Informative)
I think he exaggerated a bit. But most of the non-protected forests are replanted fast growing pine monocultures, not healthy natural forests.
Re:And yet. (Score:5, Informative)
Trees aren't equal. Fast-growing trees drain nutrients but absorb little CO2, for example. Very damaging to the environment, if planted in excess - which is why it is common in the US. Plantations are also not "woods" in any meaningful sense - woods aren't just trees, but complex ecosystems that include wildflowers, fungi, etc. Real woods don't generally have massive wildfires, those are almost invariably the consequence of plantations or excessively-managed areas. Not always, true, but natural forests with natural clearings and natural recycling of raw materials will tend to utilize forest fires to sweep out excessive trash and allow seedlings to grow -- this is obviously not possible when the heat destroys even the fire-resistant seed pods/cones and topsoil.
Some interesting numbers (Score:5, Informative)
http://www.fia.fs.fed.us/library/briefings-summaries-overviews/docs/ForestFacts.pdf [fs.fed.us]
"It is estimated that—at the beginning of European settlement—
in 1630 the area of forest land that would become
the United States was 1,045 million acres or about 46
percent of the total land area. By 1907, the area of forest
land had declined to an estimated 759 million acres or
34 percent of the total land area. Forest area has been relatively
stable since 1907. In 1997, 747 million acres—or
33 percent of the total land area of the United States—
was in forest land. Today’s forest land area amounts to
about 70 percent of the area that was forested in 1630.
Since 1630, about 297 million acres of forest land have
been converted to other uses—mainly agricultural. More
than 75 percent of the net conversion to other uses
occurred in the 19th century."
And it does go on to describe the kinds of differences - one of which you mention - between historical and contemporary forest composition.
Wot??? (Score:4, Informative)
> Everyone knows that trees give us all oxygen so we can breathe
I certainly don't know any such thing. In fact I thought forests were net zero oxygen because when trees die the decay of the tree consumes as much oxygen as the tree produced during its life. Not to mention that of course at night the tree is burning the sugars it made during the day by photosynthesis.
Plankton is where there is a possible net oxygen increase because when they go dead they can sink, and when that happens they don't decay.
Re:And yet. (Score:5, Informative)
Re:And yet. (Score:2, Informative)
Well, it is not immediately clear from the GP, but the draining/absorbing comes from different sources. While CO2 absorbtion is mostly from the air (which is why plants can grow bit in pots with little change to the soil), the nutrients are generally taken from the ground, thus "draining" it, in the absence of fertilizer or some other way to return nutrients to the ground. Most notable of these nutrients, and what is usually the limiting factor, is nitrogen (specifically, nitrates). Some trees actually leave the soil with more nitrogen, however, due to having a symbiotic relationship with nitrogen-fixing bacteria that lives in their roots, but these trees are in general not the fast-growing varieties grown in forestry. See Wikipedia [wikipedia.org] for some details [wikipedia.org].
As for the actual CO2 absorbtion rates, I would imagine that while fast-growing varieties probably absorb CO2 faster, on the whole, there is the whole density thing to consider.