Dendrology

Life as a reading of the self

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{ Vincent del Brouck }

Sudden hush across the water, and we’re here again

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In theory, the relationship between rainfall and tree cover should be straightforward: The more rain a place has, the more trees that will grow there. But small studies have suggested that changes can occur in discrete steps. Add more rain to a grassy savanna, and it stays a savanna with the same percentage of tree cover for quite some time. Then, at some crucial amount of extra rainfall, the savanna suddenly switches to a full-fledged forest.

But no one knew whether such rapid transformations happened on a global scale. (…) Holmgren’s group identified three distinct ecosystem types: forest, savanna, and a treeless state. Forests typically had 80 percent tree cover, while savannas had 20 percent trees and the “treeless” about 5 percent or less. Intermediate states — with, say, 60 percent tree cover — are extremely rare, Holmgren says. Which category a particular landscape fell into depended heavily on rainfall.

Fire may be another important factor in determining tree cover.

{ ScienceNews | Continue reading }

painting { Albert Bierstadt, Giant Redwood Trees of California, 1874 }

For you have five trees in Paradise which do not change, either in summer or in winter, and their leaves do not fall

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The genius behind the square tree was Robert Falls, who in the late 1980s was a PhD candidate in the U. of B.C. botany department. Falls noticed that some tree trunks exposed to high winds had become less round in cross section — they’d grown thicker on their leeward and windward sides to buttress themselves. Falls theorized that flexing of the bark by the wind encouraged the cambium— the layer of growth cells just beneath the bark — to produce extra wood. To test his theory, Falls subjected trees to what he thought might be comparable stress by scarring them with surgical tools. Sure enough, more wood grew at the site of the scars.

Hearing the news, a professor in the university’s wood science department suggested Falls try using this discovery to grow trees with a square cross section. Square trees would be a boon to the lumber industry. Since boards are flat and trees are round, only 55 to 60 percent of the average log can be sawed into lumber — the rest winds up getting turned into paper pulp and the like, or just gets thrown away. So Falls obligingly scarred seedlings of several species (western redcedar, black cottonwood, and redwood) at 90-degree intervals around their trunks. The trees responded as hoped, becoming “unmistakably squarish,” he tells me. (…)

Square trees were just the start. In 1989 Falls was awarded a Canadian patent for an “Expanded Wood Growing Process,” a bland title that fails to capture the revolutionary nature of the concept. Square trees by comparison are a mere novelty. The young scientist had come up with a way to grow boards.

{ The Straight Dope | Continue reading }

image { Bo Young Jung & Emmanuel Wolfs, Square Tree Trunk stool II, 2009 | bronze }

‘The tyrant will always find a pretext for his tyranny.’ –Aesop

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Substance is by nature prior to its modifications

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{ Leonard Johnson, A traveler palm tree, Philippine Islands, 1926 }

A pause. Infernal machinery.

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Ask any second grader what you can do with the rings on a tree, and they’ll respond, “Learn the age of the tree.” They’re not wrong, but dendrochronology—the dating of trees based on patterns in their rings—is more than just counting rings. The hundred year-old discipline has given scientists access to extraordinarily detailed records of climate and environmental conditions hundreds, even thousands of years ago.

The ancient Greeks were the first people known to realize the link between a tree’s rings and its age but, for most of history, that was the limit of our knowledge. It wasn’t until 1901 that an astronomer at Arizona’s Lowell Observatory was hit with a very terrestrial idea—that climatic variations affected the size of a tree’s rings. The idea would change the way scientists study the climate, providing them with over 10,000 years of continuous data that is an important part of modern climate models. (…)

Dendrochronology operates under three major principles and a handful of other ground rules. The uniformitarian principle is perhaps the most important. It implies that the climate operates today in much the same way it did in the past. The uniformitarian principle does not imply that the climate today is the same as it was in the past, or even that today’s climatic conditions ever occurred in the past. It simply states that the basic processes and limiting factors are consistent through time.

{ Ars Technica | Continue reading | Dendrochronology | Wikipedia }

photo { David Stewart }