hide
Free keywords:
-
Abstract:
The factor separation of Stein and Alpert (1993)
is applied to simulations with the MPI Earth system model
to determine the factors which cause the differences between
vegetation patterns in glacial and pre-industrial climate. The
factors firstly include differences in the climate, caused by
a strong increase in ice masses and the radiative effect of
lower greenhouse gas concentrations; secondly, differences
in the ecophysiological effect of lower glacial atmospheric
CO2 concentrations; and thirdly, the synergy between the
pure climate effect and the pure effect of changing physiologically
available CO2. It is has been shown that the synergy
can be interpreted as a measure of the sensitivity of ecophysiological
CO2 effect to climate. The pure climate effect
mainly leads to a contraction or a shift in vegetation patterns
when comparing simulated glacial and pre-industrial vegetation
patterns. Raingreen shrubs benefit from the colder and
drier climate. The pure ecophysiological effect of CO2 appears
to be stronger than the pure climate effect for many
plant functional types – in line with previous simulations.
The pure ecophysiological effect of lower CO2 mainly yields
a reduction in fractional coverage, a thinning of vegetation
and a strong reduction in net primary production. The synergy
appears to be as strong as each of the pure contributions
locally, but weak on global average for most plant functional
types. For tropical evergreen trees, however, the synergy
is strong on global average. It diminishes the difference
between glacial and pre-industrial coverage of tropical evergreen
trees, due to the pure climate effect and the pure ecophysiological CO2 effect, by approximately 50 per cent.
