"...mein Acker ist die Zeit", Aufsätze zur Umweltgeschichte - Oapen

City and Nature (2007)
Sustainability and
equilibrium
establishment of a dynamic
equilibrium under natural conditions
and over a long period
(decades or centuries)
Biodiversity species abundance
‘normal’
135
states of equilibrium in urban biotic communities
more or less ruled out because the
system will probably be destroyed before
the state of equilibrium can be attained
high diversity of sites, organisms, and biotic
communities
precisely in cities. Despite the fundamental differences between urban and nonurban
ecosystems, there are other differences that have to be stressed. They bring
into focus the functional characters and links between system elements and biological
entities (see Table 3).
Cities can be described and analysed in terms of ecological approaches, and
once they have achieved a certain stage, they even show cyclic phases of developmental
stages as other ecosystems do (see Figure 4.).
Figure 4. Cyclic model of stages of urbanization based upon population change in core
and fringe zones of urban agglomerations. Compare Table 6. Notes: U = urbanization; S =
suburbanization; D = disurbanization or counterurbanization; R = reurbanization phase.
Source: From Antrop, “Landscape Change”, Fig. 2; reproduced with permission from Elsevier.
As city ecosystems are created and maintained only by human decisions, they do
not emerge by themselves. This is why I consider this cyclic behaviour as a mere
analogy (instead of a homology), especially as it is described only for contemporary
cities. Therefore one should be wary of biological analogies which are willingly
absorbed by decadence or depravation theories that address cities as if they were
organisms and subjects of organismic evolution or selection. Those approaches are
fallacies.