Of roots that bind

LIVING HISTORY

We often underestimate the value of trees. According to researchers, they cause cooling of land and slow down erosion. Also, they act as carbon sinks.

Trees link us to our past and are our bridges to the future. They have a system of warning each other of dangers and help each other. As botanists confirm, the list of the biggest living things on earth which includes among others, the dinosaur and the blue whale, is a tree that goes by the name ‘sequoia’. The tree can be found in North California in America. It is understood that a single tree weighs more than six blue whales. Some redwood trees and Australian eucalyptus trees are more than 270 feet high and thrice as much as the length of the greatest dinosaurs. Some pine trees in Western America are more than 4,000 years old.

These trees are green machines and their value to human beings is difficult to measure.
Trees are known to send invisible signals to each other in times of distress, according to ecologists. Take the example of the willow, which is used to make cricket bats. When the trees are attacked by webworms or caterpillars, they give off a chemical which alerts nearby willows. These trees respond by pumping more tannin into their leaves which makes it more difficult for the insects to digest them. Researchers have also found similar qualities in sugar maples, birches and other trees. One of the unusual qualities noticed in them is that they respond differently to different attacks.

Trees, according to researchers, cause cooling of the land, slow down the wind evaporation, erosion and transpire water into the sky from their leaves. Scientists have found that trees may cause rain in more peculiar ways. Many species of trees are inhabited by bacteria, which promote freezing as an attacking mechanism. They generate proteins that will trigger freezing at higher temperatures than usual and the resulting ice damages the tree, giving the bacteria access to the nutrients they need.

Another amazing fact that has been discovered by researchers is regarding the growth and relationship between the same kind of trees or different kind of trees. An alliance may be developed between two trees standing side by side through microscopic substances. This is known as mycorrhiza.

Mycorrhiza is the symbiotic relationship between the mycelium of a fungus and the roots of a higher plant. The association is referred to as external in cases in which the fungus entwines the ground tissue of the ends of young roots and penetrates the intercellular spaces of the outer layers of bark.

Endotrophic or internal mycorrhiza is the implantation of mycelium inside the cells of a plant. Ectotrophic mycorrhiza occurs in many trees including oak, spruce, pine and birch.

Scientists are of the opinion that through these fungi, all the trees in a forest can be linked like a community. If one tree has access to water, another to nutrients, a third to sunlight, then the trees apparently can share these with one another.



Carbon audit

* Braced against a slope, Robert Hrubes cinched his measuring tape around the trunk of one tree after another, barking out diameters like an auctioneer announcing bids. Hrubes’ task was to calculate how much carbon could be stored within the tanoak, madrone and redwood trees in that plot. Every year or so, other foresters will return to make sure the trees are still standing and doing their job.

* Such audits will be crucial as California embarks on its grand experiment in reining in climate change. On January 1, it will become the first state in the United States to charge industries across the economy for the greenhouse gases they emit. Under the system, known as “cap and trade,” the state will set an overall ceiling on those emissions and assign allowable emission amounts for individual polluters. A portion of these so-called allowances will be allocated to utilities, manufacturers and others; the remainder will be auctioned off. Over time, the number of allowances issued by the state will be reduced, which should force a reduction in emissions. Just three years ago, California’s plan was viewed as a trial run for a national carbon market that one day might tie into existing markets in Europe and elsewhere.

* There are several basic requirements for a forest offset. Credits cannot be granted for preserving trees that were going to be left standing anyway. The change must be long-lasting: Trees must be left intact for a century. And owners must hire accredited verifiers to audit their claims. The offset marketplace is already beginning to hum as companies gear up for California’s rollout.

* Making strategic decisions about how many trees to harvest and how many to use to lock up carbon is an uncertain business. Other carbon markets have generally not done well by investors, and some brokerages have closed their carbon desks.

Felicity Barringer
New York Times News Service