Earth's water cycle and global warming. Opinions needed. Part 4?

Question

Just how much water does a tree evaporate?
How much does the oceans?
Given that only the surface of a body of water evaporates.
Would an acre of trees evaporate more than an acre of water?
Is it a hugely significant difference?
Time for real math.
Million?? Way more??? Acres of trees gone.
Trillions??? Way more??? Less water evaporating.
Hmmm... Did we screw up the earths water cycle?
Maybe its time for a new text book.
Earth's water cycle only needs buildings and roads to work properly. Who thought all those trees were needed?
Page 52 shows only skyscapers are needed for the cycle to work right. So what happened?
Cut em down. Cut em all down.
Those darn trees are killing us.

Do your part. Get a chainsaw, and lets eliminate this problem.

Later, I found this and the link. While evaporation from the oceans is the primary vehicle for driving the surface-to-atmosphere portion of the hydrologic cycle, transpiration is also significant. For example, a cornfield 1 acre in size can transpire as much as 4000 gallons of water every day.

I'm guessing an acre of tall trees would be more. 10 times more??. So an acre of trees might be 40,000 gallons in a day. Then a million acres would be 40,000,000,000 gallons, also in a day. Sounds like a lot but on a global water scale, who knows.

http://earthobservatory.nasa.gov/Library/Water/water_2.html

No questions need no solutions.

While evaporation from the oceans is the primary vehicle for driving the surface-to-atmosphere portion of the hydrologic cycle, transpiration is also significant. For example, a cornfield 1 acre in size can transpire as much as 4000 gallons of water every day.

I'm guessing an acre of tall trees would be more. 10 times more??. So an acre of trees might be 40,000 gallons in a day. Then a million acres would be 40,000,000,000 gallons, also in a day. Sounds like a lot but on a global water scale, who knows.

http://earthobservatory.nasa.gov/Library...

Some Reported Evapotranspiration Rates
In studies, water hyacinth evapotranspiration water loss has been calculated to be from 1.3 to 2.7 times greater than evaporation water loss, depending on lake location and conditions. In some studies, water hyacinth transpired up to .5 inch/day, with most loss occuring between August and October.


In one study, a single acre of water hyacinth transpired 21,000 gallons (87 tons).

ttp://earthobservatory.nasa.gov/Library..

a cornfield 1 acre in size can transpire as much as 4000 gallons of water every day.

I'm guessing an acre of tall trees would be more. 10 times more??. So an acre of trees might be 40,000 gallons in a day. Then a million acres would be 40,000,000,000 gallons, also in a day. Sounds like a lot but on a global water scale, who knows.


in one study, a single acre of water hyacinth transpired 21,000 gallons (87 tons) of fresh water per day. Water hyacinth increased water loss over evaporation losses by 30 inches per year.
An acre of open water under the same conditions would evaporate about 9,000 gallons (37 tons) of fresh water per day.

An acre of water lettuce transpired 9,000 gallons per day; salvinia transpired 8,500 gallons per day; azolla transpired 7,600 gallons per day.


http://plants.ifas.ufl.edu/guide/evaptran.html

Answer 1

From the U.S. Forest service I got this:

Case study analyses across a range of site conditions and species indicate a maximum transpiration capacity of approximately 7.5 x 10^6 liters of water per hectare per year (8 x I0^5 gallons of water per acre per year), with a range of 1.5 x 10^6 to 7.5 x 10^6 liters per hectare per year (1.6 x 10^5 to 8 x 10^5 gallons per acre per year). Variation among sites is related to species, tree size, and stocking (i.e., vegetation density) differences.

Sea surface evaporation rates seem to be harder to find. Most of my searches for sea evaporation came up with salinity studies. Salinity seems to have a big effect on evaporation rates. So do many other factors, like temperature. Obviously boiling water evaporates extremely fast and icy water does not. For fresh water, I found this at the second source:

Open water evaporation rates reported from around the world range from 30 inches/year to 103 inches/year.

Now some math to convert units. 30 -103 inches per year is 2.5 to 8.58 feet. So there are between 2.5 and 8.58 cubic feet per year evaporating from every square foot of open water. Google says 1 cubic foot = 28.3 liters, so we get about 71 to 243 liters per year per square foot. A hectare is 10,000 square meters or about 107,639 square feet. At 71 to 243 liters per square foot we get 7.6 X 10^6 to 2.7 X 10^7 liters per year per hectare. That is more than for a hectare of trees, but not hugely more.

So I conclude open water can evaporate more vapor than the same area of forest land can transpire, but not way more.

Answer 2

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