Amazon Trees Gain Mass
Scientists do not know what is causing the increase
in mass of Amazon trees during the past 20 years. Oliver Phillips of
the University of Leeds in the United Kingdom believes that the Amazon forests
have become more massive, because the amount of Carbon they absorb from
the atmosphere has increased. This indicates that they are acting
as a huge "carbon sink," and they are keeping some of the carbon they absorb.
It was thought that trees released as much carbon as they absorbed.
The latter theory is not the only explanation for the growth of forest
mass. Another theory says that there are more nutrients available because
of human activities. Forest fires are releasing nitrogen into the atmosphere.
Afterwards the nitrogen is absorbed by clouds and then returned to Earth
as rain to fertilize the forests.
There is a third possibility obtained from research led by Stephen Pacala,
an ecologist at Princeton University in New Jersey. He has studied a similar
carbon-sink effect in the United States. He thinks this is the result of
the re-growth of previously logged forests.
Let’s assume that the Amazon forests are gaining mass because of the carbon-sink
effect, and then we should ask how long the effect will last. Researches
have shown that this effect will last only a few years. The amount pf nitrogen
limits the effect. A computer modeling study done recently by Peter Cox,
a scientist at the Hadley Center for Climate Prediction in the United Kingdom,
shows that as temperatures increases, forests would possibly dry out and
become a reason of increasing the amount of CO2 in the atmosphere and not
a reason of decreasing this amount as they are now.
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Studies Measure Capacity of "Carbon
Sinks"
Scientists are getting a better idea of the amount of
carbon that Earth's forests absorb from the atmosphere, acting as "carbon
sinks." New research in this area will be very important in devising solutions
to the global warming problem. Recent studies have found that more diverse
plant ecosystems are better able to absorb carbon dioxide. When old growth
forests like this one are clear cut, timber companies often replant the
areas with a single tree species, a practice known as "monoculture," which
reduces the biodiversity.
Scientists know that forests, crops, soils, and other organic matter absorb
carbon, slowing down the rate of global warming. The results in calculating
haw much carbon is absorbed differ.
Different Measuring Techniques
How much carbon is "stored" has been measured in two ways: one atmosphere
based, the other land based.
1. Atmosphere based: measures concentrations of CO2 in the air when it
is moving from point A to point B.
2. Land base: makes an inventory of all the carbon in a given area.
Then the variation of this amount is recorded.
The results of the atmospheric methods are similar to each other, and they
have shown higher levels than the land based method. This was because in
land based methods, only the amount of carbon in tress was taken in account.
Now they took in account the carbon absorbed by landfills, soils, houses,
etc. These results are now consistent with the atmosphere based method.
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