mercredi 22 avril 2009

A tragic error in watershed management.

Once I read a story in "Trees", an yearbook of the Agricultural department of the U.S.A.. It consists of a mountain to manage adjacent to farmlands. They wanted most of the water coming from the river that feeds the mountain. They have to thin the forests of the watershed. The possibilities range from light to heavy thinnings. So the possibilities range from five to fifty percent of the forest canopy. Preposterously, they decided that the more heavy the thinning, more water will be available. So they cut at forty percent the forest lands. So they thinned the forest lands about forty percent. The reasoning was that then with fewer trees to absorb water, more water will be available. They neglected to verify what will happen with light thinnings. If you are scientific, you have to verify all the options. You cannot decide of what will be the results. It is the same people who decided that prescribed burning should be banished in resinous forest management.

Within a resinous stand, you cannot cultivate, one by one, the trees as in a hardwood forest. Because, once the stand is thinned, the seedlings will not sprout.
So, they decided that forty percent was a good measure and so, more water will be available for the farmlands. And that was a big error.

I say, if they had thinned with five or ten percent the forests regularly, the output of the river will have increased after a brief adaptation. The adaptation is the time required for seedlings to establish. At the start they would have had to thin at about the five years. After a long time, the thinning must be done at about the two years. But there is the problem that such stands were resinous (Pines). You have to do "prescribed burning" or "controlled burns". I don’t know if it will work, but prescribed burning may be replaced by raking the surface for liberating the mineral soil, as for permitting the seedlings to establish on a surface free of soil litter. It is time consuming while prescribed burning is not but requires strategy.

So, as the Quebec may lose its hydroelectric plants of the North, I say that if they had chosen thinning, prescribed burning and tree seeds planting, then there will be no problem with water out there.

As for the science behind my conclusion, be sure I would have wanted to find an university willing to evaluate my theories. I still hope to prove my point one day.

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