9 Stability Properties in the Wadden Sea
Volker Grimm, Hauke Bietz, Carmen-Pia Gi.inther, Andreas Hild,
Marlies Villbrandt, Verena Niesel, Ulrike Schleier, Sabine Dittmann
Abstract: To achieve an understanding of the processes and mechanisms responsible for the reaction of the components of the Wadden Sea to disturbances, an attempt is made to assess the stability properties of the components studied by
ELA W AT. It is discussed how this assessment depends on the choices of the variable of interest, the scale of observation, the type of disturbance, and the identification of the reference dynamics. The assessment shows that the components of
the Wadden Sea possess certain stability properties: both biotic and abiotic components exhibit low constancy or high variability at small spatial and temporal scales,
constancy (as well as resilience in the case of disturbances) at intermediate time
scales of years to several decades and spatial scales of entire tidal flats, and persistence under natural conditions at temporal scales of many decades to centuries
and for the entire Wadden Sea (or large parts thereof). Among the most important
stability mechanisms of the organisms living in the Wadden Sea are their high
taxonomic or functional diversity, their mobility and their high potential population
growth rates. Benthic organisms may react to disturbances via "resilience in-situ"
or "resilience by migration". However, the natural, tide-driven web of abiotic
processes must continue to persist if the stability mechanisms of the organisms in
the Wadden Sea are to unfurl.
9.1
Introduction
The goal of the ELA W A T project was to gain a better understanding of the properties and processes which enable the Wadden Sea to react flexibly to events such
as storms, ice winters and anthropogenic influences. Therefore natural structures
were studied, as were structure-generating processes and the manner in which the
generation of structures is affected by disturbances (Chap. 2).
Although the reaction of ecological systems to disturbances can of course be
studied without referring to stability concepts (e.g., Sousa 1980), the pivotal concept of ELA W AT was resilience, i.e. the ability of a system to return to reference
dynamics following a temporary disturbance. The motivation behind studying
resilience was to understand the processes in the Wadden Sea to a degree which
would allow a general assessment of the stability properties emerging from these
processes. Consequently, this chapter comprises a detailed discussion of the components of the Wadden Sea with respect to their stability properties (i.e. constancy,
resilience, resistance, and persistence; cf. Chap. 2).
Volker Grimm, Hauke Bietz, Carmen-Pia Gi.inther, Andreas Hild,
Marlies Villbrandt, Verena Niesel, Ulrike Schleier, Sabine Dittmann
Abstract: To achieve an understanding of the processes and mechanisms responsible for the reaction of the components of the Wadden Sea to disturbances, an attempt is made to assess the stability properties of the components studied by
ELA W AT. It is discussed how this assessment depends on the choices of the variable of interest, the scale of observation, the type of disturbance, and the identification of the reference dynamics. The assessment shows that the components of
the Wadden Sea possess certain stability properties: both biotic and abiotic components exhibit low constancy or high variability at small spatial and temporal scales,
constancy (as well as resilience in the case of disturbances) at intermediate time
scales of years to several decades and spatial scales of entire tidal flats, and persistence under natural conditions at temporal scales of many decades to centuries
and for the entire Wadden Sea (or large parts thereof). Among the most important
stability mechanisms of the organisms living in the Wadden Sea are their high
taxonomic or functional diversity, their mobility and their high potential population
growth rates. Benthic organisms may react to disturbances via "resilience in-situ"
or "resilience by migration". However, the natural, tide-driven web of abiotic
processes must continue to persist if the stability mechanisms of the organisms in
the Wadden Sea are to unfurl.
9.1
Introduction
The goal of the ELA W A T project was to gain a better understanding of the properties and processes which enable the Wadden Sea to react flexibly to events such
as storms, ice winters and anthropogenic influences. Therefore natural structures
were studied, as were structure-generating processes and the manner in which the
generation of structures is affected by disturbances (Chap. 2).
Although the reaction of ecological systems to disturbances can of course be
studied without referring to stability concepts (e.g., Sousa 1980), the pivotal concept of ELA W AT was resilience, i.e. the ability of a system to return to reference
dynamics following a temporary disturbance. The motivation behind studying
resilience was to understand the processes in the Wadden Sea to a degree which
would allow a general assessment of the stability properties emerging from these
processes. Consequently, this chapter comprises a detailed discussion of the components of the Wadden Sea with respect to their stability properties (i.e. constancy,
resilience, resistance, and persistence; cf. Chap. 2).