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Chinese Journal of Population, Resources and Environment 2005 Vol. 3 No.2
Corresponding author: Qi Ye (yeqi@bnu.edu.cn)
1 INTRODUCTION
Evapotranspiration (ET) is the key process controlling the
exchange of energy and hydrologic flux for vegetated
surface. Terrestrial net primary productivity (NPP)
represents the carbon available for plant allocation to
leaves, stems, roots, defensive compounds, reproduction
and is the basic measure of biological productivity. Tree
growth, forage available for grazing, food productivity,
and atmospheric CO
2 levels are all strongly controlled by
NPP (White et al., 2000).The exchange of carbon, water
and energy between vegetation and atmosphere are
important determinants of regional and global carbon
budgets (Denning et al., 1995). Regional flux rates of
carbon dioxide and water from terrestrial vegetation must
be known in order to understand the interaction of the
biosphere with the hydrosphere and atmosphere, and also
to determine the response of the terrestrial ecosystem to
climate change.
Numerical models of carbon, water and nutrient budgets
Modeling Carbon and Water Budgets in the
Lushi Basin with Biome-BGC
Dong Wenjuan, Qi Ye, Li Huimin, Zhou Dajie, Shi Duanhua
& Sun Liying
School of Environment, Beijing Normal University, Beijing 100875, China
Abstract: In this article, annual evapotranspiration
(ET) and net primary productivity (NPP) of four
types of vegetation were estimated for the Lushi basin,
a subbasin of the Yellow River in China. These four
vegetation types include: deciduous broadleaf forest,
evergreen needle leaf forest, dwarf shrub and grass.
Biome-BGC--a biogeochemical process model was
used to calculate annual ET and NPP for each
vegetation type in the study area from 1954 to 2000.
Daily microclimate data of 47 years monitored by
Lushi meteorological station was extrapolated to
cover the basin using MT-CLIM, a mountain
microclimate simulator. The output files of MT-
CLIM were used to feed Biome-BGC. We used
average ecophysiological values of each type of
vegetation supplied by Numerical Terradynamic
Simulation Group (NTSG) in the University of
Montana as input ecophysiological constants file.
The estimates of daily NPP in early July and annual
ET on these four biome groups were compared
respectively withfield measurements andother studies.
Daily gross primary production (GPP) of evergreen
needle leaf forest measurements were very close to
the output of Biome-BGC, but measurements of
broadleaf forest and dwarf shrub were much smaller
than the simulation result. Simulated annual ET and
NPP had a significant correlation with precipitation,
indicating precipitation is the major environmental
factor affecting ET and NPP in the study area.
Precipitation also is the key climatic factor for the
interannual ET and NPP variations.
Key words: Carbon and water budgets, Biome-
BGC, the Lushi basin, evapotranspiration, net
primary productivity (NPP), gross primary
production (GPP)
ARTICLES