While climatic conditions primary
determine the
distribution and functioning of plant ecosystems, plant
ecosystems also affect the climate, particularly through
evapotranspiration, albedo, carbon cycle, and roughness of
land surface. The degree, the sign (negative or positive),
and
the geographical distribution of the vegetation feedbacks
on
climate will all play a role in determining the final state
of
climate and final state of distribution and functioning of
terrestrial ecosystems.
Thus, for providing reliable predictions for the changes of
global climate, integrated terrestrial ecosystem models that
include biogeochemical processes and vegetation dynamics
would be required. However, a long time lag between
climatic changes and changes in plant ecosystem adapting to
the new climate are predicted, which makes the situation
more complicated. As such time lags are complex, and due to
diverse function of many factors (such as seed dispersal,
establishment conditions/rate, and growth rate), there are
no
reliable predictions at this moment.
To overcome this concern, we have been developing
the model, SEIB-DGVM. This is one of DGVMs that can
simulate changes in ecosystem functions (ex: carbon and
water flux) and ecosystem structures (ex: distribution and
composition) (Fig.1). Among existing DGVMs, only |
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SEIBDGVM
simulates local area interactions of individual trees
within a spatial explicit virtual forest; several sample plots
are
placed at each grid box, and calculate growth, competition,
and decay of each individual tree within the plots by
considering light conditions of each tree surrounded by other
trees (Fig.2).
This representation of plant dynamics has important
advantages over previous DGVMs; (1) competition and
succession dynamics are adequately represented, and hence
response of ecosystem to climatic change would be
reasonably predicted, (2) formation and recovery of forest
gaps and subsequent carbon behavior can be included, and
(3) information on the forest structures and dynamics can
be
directly applied for parameter estimation and validation
without introducing many additional assumptions.
Currently, development of the SEIB-DGVM is almost
completed. After verifying its reliability, we will incorporate
it into the Kyousei2-Integrated-Synergic-Sytem-Model-of-Earth
(KISSME), which simulates possible consequences of
climate-ecosystem interactions on the global change. |