When thermodynamic systems are moved away
from their local equilibrium, they shift their state in a
way which opposes the applied gradients and moves
the system back towards its equilibrium attractor. In
simple terms, systems have the ability to resist being
moved from equilibrium and a tendency to return to
the equilibrium state when moved from it (Schneider
and Kay, 1993). The breakdown of stability into the
two principal components resistance and resilience ( as
suggested by Webster et al., 1975) seems therefore
appropriate to gain a certain degree of simplification in
order to discuss and visualize the most important
aspects of ecological stability. Correspondingly,
(Grimm et al., 1992) rank resistance and resilience
among the most important stability concepts related to
specific properties and measures in ecological systems.
Resistance (inertia, immovability) comprises the
ability of a system or the component in focus to resist
external stress. An ecosystem feature that is easily
changed has a low resistance, whereas one that is difficult
to displace is resistant and in this sense stable.
Resilience (recoverability) comprises correspondingly
the ability of a system feature, when changed by
a perturbation, to return to its former dynamic state. A