Conservation and Sustainable Use of the Biosphere - WBGU

Biogeographical criticality F 5.3
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sent the regional biospheric transpiration output on
a global scale.
F 5.3.2
Identification of biogeographic regions of
importance for the Earth System
Taking all of the biospheric functions outlined above
together in the form of intersecting thematic maps of
biospheric ‘energy intake’, ‘thermostat effect’ and
‘influence of the global hydrological cycle’ already
shows a rough approximation of the most important
biogeographical regions of the Earth (Fig. F 5.3-1).
Outstanding biogeographical regions are either characterized
by high intake of solar energy, an important
role within the hydrological cycle, a stabilizing effect
on albedo in the local biosphere or a combination of
these aspects.
By linking this representation with another value
in the criticality function, robustness R, furthermore
a particular protective merit of the regions may be
derived. To assess R, which designates a stability criterion
within the local biosphere, a worldwide representation
of local sensitivity of net primary production
for precipitation and temperature changes was
used. From a random sample of NPP at over 62,000
locations and the associated climate (air temperature
close to the ground, precipitation, light penetration
with consideration for cloud cover, etc) a statistical
correlation model was drawn up. To ascertain sensitivity
of NPP vis-à-vis climatic changes it uses a neuronal
network (Moldenhauer and Lüdeke, 1999;
Lüdeke et al, 1999) that quantifies the functional
dependency of NPP on certain climate values. The
resultant global map shows in which regions of the
world NPP is relatively stable in the face of climate
fluctuations and where major effects are to be
expected from minimal climatic changes. Combining
this result with the map shown in Fig. F 5.3-1 then
identifies those biogeographical regions that equally
have an important function for the Earth System and
react sensitively to changes in environmental conditions
(Fig. F 5.3-2).
Certain critical regions are outlined below. In the
Northwest of the United States, an East-West strip
(circle 1 in Fig. F 5.3-2) was identified as critical running
within the Rocky Mountains parallel to the
Canadian border. The vegetation types in this region
vary between boreal mixed forest, coniferous forest
and grassland and are at risk from human influence
particularly in the regions around Seattle and Portland,
through deforestation (clear-cutting) or the
spread of settlement (Urban Sprawl Syndrome; cf
also Chapter G, Fig. G 4.2-3).
The Atlantic coastal area of the Amazon together
with Guyana, Surinam and Brazil is another important
and fragile region (circle 2 in Fig. F 5.3-2). In that
Importance of
biogeographic regions
Low
High
Figure F 5.3-1
The importance of biogeographic regions for the Earth System in the context of energy absorption, the thermostat effect and
the hydrological cycle.
Source: WBGU