Email to a friend
Fishbone deforestation pattern
affecting environment, research shows
photo to enlarge
by L. Brian Stauffer
Baidya Roy, a professor of atmospheric
sciences at Illinois, is studying the atmosphere
dynamics of fishbone deforestation.
CHAMPAIGN, Ill. —
Researchers at the University of Illinois at Urbana-Champaign are studying
the environmental impact that unique patterns of deforestation in Rondonia,
Brazil, have on the land and climate.
Rondonia is a state in the Amazonian region where the establishment
of rural development projects has resulted in the construction of orthogonal
road networks. Deforestation along the rapidly expanding network of
highways and local roads has created a unique fishbone pattern.
Somnath Baidya Roy, a professor of atmospheric
sciences at Illinois, is studying the atmosphere dynamics of fishbone
deforestation, and will present his findings at the American Geophysical
Union meeting in San Francisco, Dec. 11-15.
“People often relate tropical deforestation to clear-cuts,”
Roy said. “Climate models show that clear-cuts, if they happen
on a basin-wide scale, will result in decreased rainfall and bring about
a drier, more arid landscape. In the case of fishbone patterns, the
deforestation is in isolated segments of the landscape, and our models
indicate that it results in increased precipitation over these deforested
Whether there has been a change in the overall amount of precipitation
has not been established, but there is definitely evidence for the redistribution
of precipitation. Roy attributes this redistribution to “vegetation
breezes” that are similar to lake and sea breezes.
A deforested patch is warmer than the neighboring forests. Warm air
is lighter and rises, creating a localized low-pressure zone. Cool air
then rushes in to fill the void. Because of this convergence, more cumulus
clouds and rainfall occur over the deforested patch.
Roy uses a high-resolution computer simulation model to study the effects
of deforestation on climate, and the effects that climate change has
on the landscape, a process known as “feedback cycle.”
Recent studies have indicated that fishbone deforestation can trigger
up to 15 millimeters more rain over pastures, stimulating an increased
growth of vegetation in these areas.
“It is very counter-intuitive that in these cases, fishbone deforestation
results in a negative feedback-cycle,” Roy said. “It’s
negative because it speeds up vegetation recovery and thus offsets the
effects of deforestation.”
If the deforestation had resulted in less rainfall, leading to a decrease
in plant growth, this would be referred to as a “positive”
Roy’s model is high-resolution, resulting in very detailed data.
The drawback to this model is that it cannot be carried out for prolonged
periods, unlike more conventional climate models, which provide coarser
data but can be carried out continuously.
“Our next goal is to correlate my model with other climate models,”
Roy said, “so that we may study the longer term aspects of fishbone
deforestation, while maintaining the high-resolution.”
Editor’s note: To reach Somnath Baidya
Roy, call 217-244-1123; e-mail: firstname.lastname@example.org.