Tuesday
December 13, 2005
news@michigandaily.com
W : Sdjtauftg
SCIENCE
5
'U' biology station helps with climate-change research
By A.J. Hogg U For the Daily
Chris Vogel believes climbing a 160-foot-tall ladder in a snowstorm
is one of the best cardiovascular workouts in science. "It's not dan-
gerous," the University research scientist quipped. "Just cold." But
when an instrument fails on the University of Michigan Biological Station
Flux Tower, he doesn't have any choice but to climb.
Built in 1997, the tower is part of Ameriflux, an umbrella organization
of nearly 150 research sites stretching across the Americas, from Canada
to Argentina. Ameriflux is an effort to understand the way different eco-
systems - such as tundra and farmland - respond to changes in carbon
dioxide in the atmosphere.
Knowing this, researchers can predict how land-based ecosystems will
respond to climate change. In the forest ecosystem, the Flux Tower con-
tributes by measuring the addition and removal of carbon dioxide from
the atmosphere.
"It's a great resource that frames a lot of what we do," said Ecology
and Evolutionary Biology professor Knute Nadelhoffer, who is also the
Biological Station director. "It allows us to put biological and ecological
measurements into a region and climate context."
Situated in the middle of a University-owned forest located in the
10,000-acre Biological Station, the Flux Tower, a collaboration with
researchers from Ohio State University and Indiana University, is located
20 miles south of the Mackinac Bridge.
The tower will help answer one major question facing the researchers:
How can forests help mitigate climate change by removing carbon dioxide
from the atmosphere?
All the fossil fuel burned today - the source of the excess carbon diox-
ide that is causing climate change - was once plant litter. That dead plant
material fell to the ground, was buried, and converted over long periods
of time into oil or coal.
Nadelhoffer says research at the Flux Tower aims to shed light on how
quickly today's ecosystems are sending that carbon back into the earth
rather than into the atmosphere. "What proportion of annual tree growth
is getting stored, as the end product of plant litter decomposition, in soil
over the longer term?" he asks.
How quickly forests and other ecosystems can do this is a key ques-
tion that researchers have yet to fully understand. Nadelhoffer likens it
to "storing a little for retirement in a 401K - but in this case, you don't
know how much you are contributing."
"You toss your money - your carbon - on the forest floor and wait
to see how much is lost. It's like negative interest," he said. Much of the
carbon is cycled through plants or animals again and again before it goes
into long-term storage in the ground.
To accurately measure the flux, or transfer, of carbon dioxide, the
Flux Tower team has installed instruments recording wind speed, wind
direction, carbon dioxide concentration, temperature and humidity 10
times per second.
That means they collect 36,000 data points for each measurement every
hour. These measurements are converted into hourly data points that tell
researchers how much water, heat and carbon dioxide is moving up from
or down into the forest.
But you don't need high-tech instrumentation to get a practical lesson
in how the forest affects the atmosphere.
When a new instrument needs to be installed on the tower, Vogel
starts on the forest floor, next to a research building about half the
size of a semi-trailer. It hums with the sound of pumps pulling air
samples from the top of the tower to the ground. About 40 feet above
the surface, he finds himself surrounded by the branches of the forest
canopy. As he climbs past the tips of the trees, he is still 70 feet below
the tower top.
"There is nothing like actually experiencing the sudden increase in
wind speed as you climb above the canopy," Vogel said. "You just don't
get that from a graph of the data."
"It allows us to put biological and
ecological measurements into a
region and climate context."
- Knute Nadelhoffer
Ecology and Evolutionary Biology Professor
The tower data, however, measures only the net transfer of carbon
dioxide as measured from the top of the tower. To double-check this
measurement, the Flux Tower team also measure the biological pro-
cesses within the forest.
These ground measurements include tree diameter growth, the amount
of leaves on the trees, the amount of carbon dioxide coming from the soil,
and other sources and sinks for carbon in the forest.
The comparison of the ground and tower measurements surprised
Vogel.
On a yearly basis, the two sets of data only match within about 25 percent.
But once the Flux Tower data were added up over a five-year period, the two
data sets began to converge. This led to the realization that there seems to be
a one-year lag between the tower data and the ground-based data.
One hypothesis of the cause of this "mystery carbon" is that the trees
take it from the atmosphere in the fall, and store it as starch in their
stems and roots. The carbon uptake doesn't show up as growth until the
following year.
Although the cold weather has slowed research for now, Vogel hopes to
catch the mystery carbon once the leaves bud in the spring.
Mice grow human brain cells
. after stem-cell injections
High-tech for seniors
moves beyond The
Clapper and Life Alert
Research draws
concerns over mixing
human and animal cells
SAN FRANCISCO (AP) - Add
another creation to the strange scien-
tific menagerie where animal species
are being mixed together in ever more
exotic combinations.
Scientists announced yesterday
that they had created mice with small
amounts of human brain cells in an
effort to make realistic models of neu-
rological disorders such as Parkinson's
Still, the work adds to the growing
ethical concerns of mixing human and
animal cells when it comes to stem cell
and cloning research. After all, mice
are 97.5 percent genetically identical
to humans.
"The worry is if you humanize them
too much you cross certain boundar-
ies," said David Magnus, director of
the Stanford Medical Center for Bio-
medical Ethics. "But I don't think this
research comes even close to that."
Researchers are nevertheless begin-
ning to bump up against what bioethi-
cists call the "yuck factor."
Three top cloning researchers, for
human and animal tissue is vital to
ensuring that experimental drugs and
new tissue replacement therapies are
safe for people.
Others have performed similar
experiments with rabbit and chicken
eggs while University of Califor-
nia-Irvine researchers have reported
making paralyzed rodents walk after
injecting them with human nerve
cells.
Doctors have transplanted pig valves
into human hearts for years, and scien-
tists have injected human cells into lab
animals for even longer. But the brain
poses an additional level of concern
WASHINGTON (AP) - One day, people with
Alzheimer's disease could have telephones that
show them a picture of the caller and remind
them who it is and when they last talked.
They might walk across a floor with sensors
that check their gait and sound an alarm if they
fall. Others might relax on a bed that monitors
their pulse and breathing.
New technologies for seniors, supplementing
conveniences like The Clapper and emergency
warnings like Life Alert, are on display this week
at the White House Conference on Aging.
There are four main focus areas for the new
innovations, Dishman said: disease prevention,
early detection, caregiver support and maintain-
ing independence.
Take Intel's phone for those with early and
developing cases of memory-wasting Alzheim-
er's.
A screen like that of a computer monitor sits
next to the phone. No more embarrassing pauses
while the person getting the call tries to remem-
ber who Christine is. Using caller ID technology,
the screen can provide a photo of the caller, tell