Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Research System for Global Change
ation effect was apparently different between C -dominated
forests and C -dominated grasslands. Long-term
simulation suggests that δ C of the terrestrial biosphere
has gradually decreased during the last decades.
A considerable magnitude of isotopic disequilibrium
was found between the atmosphere and biosphere.
However, the interannual variability of isotopic disequilibrium
is shed by the seasonal change and spatial
difference. These results may carry implications for the
inversion analyses of global carbon cycle based on
atmospheric CO and its isotopic composition data.
Furthermore, to investigate the response of terrestrial
carbon budget to the future climate change, a series of
off-line simulations was performed. As a result of the
drastic increase in atmospheric CO and global warming,
plant productivity was estimated to increase by
approximately %, leading to net carbon accumulation
into biomass storage. At the same time, the
warmer climate enhanced microbial soil decomposition,
and soil organic carbon was estimated to the
release of carbon to the atmosphere.
Furthermore, we conducted simulation by using
three climate scenarios and obtained a different
response for each in terms of net ecosystem carbon
(Figure ). This finding allows us to recognize the
importance of introducing the carbon cycle feedback
into the next generation climate model.
b. Ecosystem Architecture Model Group
The objective of this group is to forecast long-term
(-year) changes in forest ecosystems, which form the
largest terrestrial organic carbon pool, in response to climate
and environmental changes. For this, we have
modeled ecological processes at various scales by concentrating
on three-dimensional ecosystem architecture.
In FY , we further revised the shoot-modulebased
simulator, PipeTree, targeting a sub-alpine coniferous
forest of central Japan, and developed individualtree-based
model for deciduous forest systems in
northern Japan. We also took a new modeling
approach as a sub-model of Sim-CYCLE to predict the
forest boundary change with global warming in taigatundra
boundary. In addition, PipeTree has been
applied for the observed natural regeneration processes
of the subalpine species. This study suggested that contact
stimulus between nearby branches had additional
Fig.14 Temporal variation in total terrestrial carbon storage from 1950 to 2099, estimated by Sim-
CYCLE simulation. IPCC-SRES A2 atmospheric CO 2 scenario and climate projections by
CCSR/NIES, CCCma, and HadCM3 climate models were assumed.
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