 |
|
|
 |
|
 |
| |
Welcome to ProQuest-CSA, your Guide to Discovery. ProQuest-CSA helps researchers worldwide find and manage relevant information in their field. If you're a member of an academic institution you may have access to CSA Illumina. Please contact your library to find out. |
|
 |
|
 |
|
Responses of net ecosystem exchanges of carbon dioxide to changes
in cloudiness - Results from two North American deciduous forests
Gu, Lianhong | Fuentes, Jose D | Shugart, Herman H | Staebler, Ralf
M | Black, T A
Journal of Geophysical Research. Vol. 104, no. D24, pp. 31,
421-31, 434. 27 Dec. 1999
We analyzed half-hourly tower-based flux measurements of CO2 from
a boreal aspen forest and a temperate mixed deciduous forest in
Canada to examine the influences of clouds on forest carbon
uptake. We showed that the presence of clouds consistently and
significantly increased the net ecosystem exchanges (NEE) of CO2
of both forests from the level under clear skies. The enhancement
varied with cloudiness and solar elevation angles, and differed
between the two forests. For the aspen forest the enhancement at
the peak ranged from about 30 percent for the 20-25-deg interval
of solar elevation angles to about 55 percent for the 55-60-deg
interval. For the mixed forest the enhancement at the peak ranged
from more than 60 percent for the 30-35-deg interval of solar
elevation angles to about 30 percent for the 65-70-deg interval.
Averaged over solar elevation angles greater than 20 deg, the
aspen and mixed forests had the maximal NEE at irradiance
equivalent to 78 and 71 percent of the clear-sky radiation,
respectively. The general patterns of current sky conditions at
both sites permit further increases in cloudiness to enhance their
carbon uptake. We found that both forests can tolerate exceedingly
large reductions of solar radiation (53 percent for the aspen
forest and 46 percent for the mixed forest) caused by increases in
cloudiness without lowering their capacities of carbon uptake. We
suggest that the enhancement of carbon uptake under cloudy
conditions results from the interactions of multiple environmental
factors associated with the presence of clouds. (Author)
 Descriptors: ECOSYSTEMS | CARBON DIOXIDE | FORESTS | CLOUDS | NORTH AMERICA | REGRESSION ANALYSIS | CARBON
|
|
|
|
