| Fig. 3.2.5. The effect of dominance by a single type of organism on ecosystem processes. A Removal of a dominant species by a stress has a greater impact than the loss of a rare species. B If a keystone species dies out then the ecosystem is affected more than expected from the comparatively small proportion of biomass that was removed by extinction of the keystone species. The effect is much greater than for species whose function can be replaced (redundant species). C Depending on the structure (plant life form) of the predominant vegetation, there are various stable states that the ecosystem can develop with increasing or decreasing biodiversity. The dotted line shows alternative states that an ecosystem under moderate stress could return to. Points A and B are threshold values at which the system changes from one state to another. (Sala et al. 1996; WBGU 1998)

Bayreuth, 1996- 1998

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