From outer space, a new dilemma for old-growth forests

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Old Growth Douglas Fir.
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A new study using laser pulses shot from satellites has found that the world's tallest forests are those along the Pacific Northwest coast. Though the findings shouldn't shock anyone who grew up in the region, they offer another indication of how important these ancient trees eventually could become.

The temperate forests of Douglas fir, Western hemlock, redwoods and sequoias that stretch from northern California into British Columbia easily reach an average height of more than 131 feet. That's taller than the boreal forests of northern Canada and Eurasia, tropical rainforests and the broadleaf forests common in much of the United States and Europe. The only forests that come close are in Southeast Asia, along the southern rim of the Himalayas and in Indonesia, Malaysia and Laos.

As scientists try to unravel the mystery of missing carbon, increasing attention is focused on these forests.

From 15 percent to 30 percent of the 7 billion tons of carbon that are released globally every year is unaccounted for, government scientists say. About 3 billion tons remain in the atmosphere, and the oceans absorb 2 billion tons. Vegetation, including the forests, probably absorbs the remaining 1 billion to 2 billion tons, but no one knows for sure how much and where.

Scientists suspect that the forests with the biggest trees store the most carbon, and the Northwest forests are probably among the largest carbon sinks in the world. However, they also say that while slower-growing older trees store more carbon, younger trees also absorb more carbon as they grow rapidly. That sets up a debate about how forests should be managed, particularly whether older trees should be cut to make way for younger ones or whether they should be protected to store the carbon they contain.

"It's a hot topic," said Elaine Oneil, a research scientist at the University of Washington's School of Forest Resources and the executive director of a consortium that's been studying the issue. "We can't afford a one-size-fits-all solution. We can't lock it all up, and it's not feasible to cut it all for 2-by-4s."

Ongoing studies using the satellites and lasers may provide valuable information on how fast the forests are growing and how much carbon they store.

More: http://www.miamiherald.com/2010/08/30/1798747/from-outer-space-a-new-dilemma.html#ixzz0yAWUFEUw

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