Birch Trees To Edge Out Aspens In Warming World

Birches will likely drive out many aspens in northern forests as mounting levels of carbon dioxide force the trees to compete more fiercely for soil nutrients in the coming decades, a University of Michigan researcher and his colleagues have concluded

Carbon dioxide is emitted when fossil fuels are burned, and it's a heat-trapping gas blamed for global warming. But rising carbon dioxide levels also have a fertilizing effect on trees and other plants, making them grow faster than they normally would.

At a 38-acre experimental forest in northeastern Wisconsin, U-M microbial ecologist Donald Zak and his colleagues have been pumping extra carbon dioxide into the tree canopies since 1997 to simulate atmospheric conditions expected in the latter half of this century. The forest contains several thousand trembling aspen, paper birch and sugar maple trees.

Mixed aspen-and-birch stands bathed in extra carbon dioxide grow about 45 percent faster than their untreated neighbors. To sustain that speedy growth, the experimental trees had to find a way to extract more of the essential nutrient nitrogen from the soil.

It appears that the extra carbon dioxide (CO₂) helps the trees do just that, by allowing them to grow more roots and "forage" more successfully for nitrogen, said Zak, a professor at the U-M School of Natural Resources and Environment and the Department of Ecology and Evolutionary Biology.

The birch trees seem better at nitrogen foraging than aspens, said Zak, one of the lead scientists at the federally funded experiment in Rhinelander, Wis. In mixed stands of aspen and birch subjected to elevated carbon dioxide levels, birch trees increased recent nitrogen acquisition by 68 percent, compared to a 19 percent increase among the aspens.

"The implication from that experiment is that it could alter the abundance of birch and aspen-in places like Michigan-by favoring birch," Zak said.

In another study being published online in the Proceedings of the National Academy of Sciences, Zak and colleagues at three other experimental forests say current models about how ecosystems will respond to mounting carbon dioxide fail to include their critical recent findings about nitrogen foraging.

Climate researchers and ecosystem modelers assume that in the coming decades, CO₂'s fertilizing effect will boost the growth rate of northern temperate forests for some unknown period of time. But eventually, current models say, the growth spurt will grind to a halt because the plants won't be able to get the soil nitrogen needed to sustain it.

But in the PNAS paper, Zak and his colleagues say enhanced nitrogen-foraging abilities should allow trees to keep the fast-growth train chugging right along.

And that's significant because forests are important carbon "sinks." They pull carbon dioxide gas out of the air during photosynthesis and lock the carbon away, for a time, in tree tissues.

In doing so, forests could help dampen the heat-trapping effects of rising carbon dioxide -- if they sustain this greater growth and nutrient uptake as they mature. If the period of CO₂-enhanced tree growth persists longer than scientists previously believed, then the climate-buffering effects of northern temperate forests could be greater than they'd assumed.

"Some of our initial assumptions about ecosystem response are not correct," Zak said. "Elevated CO₂ increases the ability of these forest trees to get limiting nutrients out of the soil. And that's a mechanism that's not in our current conception of how CO₂ will affect the way forests work."

The journal of Global Change Biology article was published online August 6. Zak and former U-M researcher William Holmes are authors of both the PNAS and Global Change Biology papers. Other authors of the PNAS article are from Boston University, Oak Ridge National Laboratory, Duke University, the University of Tennessee, the U.S. Forest Service, the College of Charleston, and several European institutions. Other authors of the Global Change Biology paper are from Michigan Technological University, North Carolina State University, and the U.S. Forest Service

Technorati : Birch, Edge . Aspens, Trees, Warming, World

Linux will be on a Third of Smart Phones in 2012

pb:24hours news

By 2012, Linux will be running on nearly 31 percent of all smart devices, thanks to a growth rate faster than Windows Mobile and Symbian, according to predictions from a research firm.

Linux smartphones will grow at more than 75 percent per year, according to ABI Research, and will be running on 331 million devices by 2012.

"Serious initiatives from the likes of Intel and Access are gathering pace and momentum, whilst the carrier community continues to identify Linux as one of the few operating systems that it intends to support in its long-term plans," said ABI research director Stuart Carlaw.

Symbian won't be too pleased with the figures, as it claims to currently have 72 percent of the smartphone market. However, Symbian's figures are very regional: it has around 90 percent of the Europe and "rest of the world" sectors, but it hasn't cracked the U.S. (it has less than ten percent there) and is only around 65 percent of the market in China and Japan, according to Canalys figures that Symbian quotes.

In China and Japan, Linux smartphones already have more than 30 percent market share, having grown massively since 2004 as earlier Canalys graphs show.

Access, which owns the Palm operating system, has created the Access Linux Platform (ALP). It is also planning a move to Linux for the Palm OS. Intel, meanwhile is supporting Linux in its ultra-mobile platform.

"Linux is benefiting from growing support in the handset OEM community, most notably Motorola, but also Nokia with less traditional types of devices aimed at mobile broadband applications," said Carlaw.

Motorola has revealed plans to have Linux on 60 percent of its handsets within the next two years, and founded the LiMo group.

Nokia, meanwhile is heavily committed to Symbian, but has put Linux on its N800 Internet tablet .

The other wild card is Google. The company's entry into the phone hardware market is still rumor but most of the latest rumors suggest a Linux-based phone.

Technorati : Smart Phones