Tree power

Do forests bring rain? Or does rain bring up forests?

A paper in BioScience Magazine called How Forests Attract Rain discusses a mostly overlooked hypothesis that explains how big rainforests actually drive the entire global water cycle. Forests pull in large amounts of water vapor from surrounding regions and from nearby bodies of water. As the vapor condenses into rain, the local atmospheric pressure drops. This sucks in more water vapor from outside the forest. It rains and the process goes on.

The whole rainforest-water vapor system is called a biotic pump because the living forest matter is what’s moving the water.

Forests also extract water and minerals from the soil, much of the water is transpired as a bi-product of photosynthesis. This makes the forest a moist damp area and keeps it cool during the day. During the night the moist air that is not generally blown away, starts condensing the moisture as dew, returning the water to the soil and keeping the night temperature warmer than it otherwise would have been. It takes time for the soil to develop its water cycle.

Planting of trees should help in bringing rains to an area, but caution is needed not to opt for monoculture.

The study explains why we see heavy downpours in the tropics as compared to the temperate or arid zones.

Anyway, Indonesia has hit upon a novel idea to reforestation – get every couple tying the knot to plant 10 saplings. And every pair that divorces has to plant 50 more saplings!

Two years ago, Indonesia was noted in the Guinness Book of Records for a dubious distinction--achieving the world's fastest rate of deforestation, cutting down an area the size of 300 soccer fields every hour, for a total of 4.4 million acres a year. The result was disastrous.

Well, it is clear that we need trees more than they need us. They give us the oxygen we need. They absorb carbon dioxide. They keep the soil intact. They bring rains. Any doubts why we must save them?