Marine Ecosystems Research Department - jamstec japan agency ...

Japan Marine Science and Technology Center
Frontier Research System for Global Change
effects on lower branch shedding besides conventionally
known shortage of light source (figure ).
In addition, we launched research on dynamic global
vegetation models (DGVM), which will play a critical
role in constructing ecosystem models in the future.
c. Ecosystem Geographical Distribution Model Group
The objectives of Ecosystem Geographical
Distribution Model (EGDM) Group are remotely sensed
satellite observations to monitor and model terrestrial
ecosystems and their relation to environmental and climate
variability. We focused on the effects of snow
cover on vegetation dynamics in Northern Hemisphere
land areas and satellite-based photosynthetically active
radiation (PAR) and its role in terrestrial primary production
and ecosystem-atmosphere carbon exchange.
In FY , we used -year satellite observations of
snow cover, vegetation greenness (measured by the
normalized difference vegetation index, NDVI), and air
temperature data for North Eurasian land areas to
examine the spatial and temporal patterns in the relation
between snow cover, climate, and vegetation growth
(Figure ). Since reliable data on the global distribution
and temporal variability of PAR are essential to
accurate modeling of the terrestrial carbon cycle, we
applied PAR data obtained from a tropical site in northcentral
Thailand into a two-leaf (sun-shade) model of
forest canopy photosynthesis. The results show that
daily net canopy photosynthesis increases with increasing
diffuse fraction (DF) (when the total available PAR
becomes a limiting factor). These results reinforce past
studies that have relied on modeled or empirical estimates
of PAR. This research contributes to improving
latitude
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day of year
latitude
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b
-0.02 -0.01 0.00 0.01 0.02
ZFSF (linear trend, fraction/yr)
50 100 150 200 250 300 350
day of year
latitude
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c
0.000 0.002 0.004 0.006 0.008
ZNDN (linear trend, fraction/year)
50 100 150 200 250 300 350
day of year
-0.20 -0.10 0.00 0.10 0.20
ZT (linear trend, deg. C/yr)
Fig.15 View of 54-year-old stand of subalpine fir forest, simulated
by PipeTree.
Fig.16 Linear trends (1982-1999) in (a) zonal snow-cover (ZFSF), (b)
normalized NDVI (ZNDN), and (c) air temperature (ZT). For
ZNDN and ZT, only active growing season values are displayed
(days in which the 18-year mean ZT > 0 degrees C).
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