Ecological sustainability and biodiversity

The immense complexity of ecosystems severely hampers the underpinning of the ecological sustainability paradigm. The few existing definitions of ecological sustainability, such as ecosystem health, are based on the obsolete superorganism paradigm of ecosystems, assuming an equilibrium for every ecosystem. New, anthropocentric approaches, like the ecosystem integrity concept, surmise that ecosystems are dynamic, loosely defined assemblages of species, which necessitates adaptive management. Another complicating factor is our poor understanding of the complex relation between biodiversity and ecosystem functioning. The few hypotheses about the role of species in ecosystems, like the rivet popper and the functional redundancy hypotheses, are not universally applicable. The functional importance of an individual species is unpredictable and context-dependent, even for keystone species. Biodiversity buffers changes in environmental conditions and might be considered as a kind of insurance.