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Biodiversity and ecosystem resilience

The decline of biodiversity globally, most severely manifested in freshwater systems (MEA 2005b), has renewed interest in ecosystem conservation and management and in the links between bio- diversity and ecosystem functioning (Holling and others 1995; Tilman and others 1997), including the role in human well-being (MEA 2005c) and the links to poverty (Adams and others 2004; WRI and others 2005). Many people highlight the ethical argument for conserving biodiversity for its own intrinsic value, and projects aimed at conserving endangered species (establishment of protected areas, changed land-use practices) have been common investment strategies, with different social outcomes (Adams and others 2004).

Research in recent decades has illustrated the importance of species diversity for ecosystem functioning (see photos of wetland biodiversity). The general theory is that a more diverse system contributes to more stable productivity by providing a means of coping with variation.

Photo by C. Max Finlayson



Photo by C. Max Finlayson

Crocodile Elephants

However, it has recently been argued that it is not the richness of species that contributes to eco- system functioning, but rather the existence of functional groups (predators, pollinators, herbivores, decomposers) with different and sometimes overlapping functions in relation to ecosystem process- es (Holling and others 1995). To understand the role of diversity for ecosystem functioning, it is necessary to analyze the identities, densities, biomasses, and interactions of populations of species in the ecosystem, as well as their temporal and spatial variations (Kremen 2005). Diversity of organ- isms within and between functional groups can be critical for maintaining resistance to change.

Species that may seem redundant during some stages of ecosystem development may be criti- cal for ecosystem reorganization after disturbance (Folke and others 2004). Response diversity (the differential responses of species to disturbance) helps to stabilize ecosystem services in the face of shocks (Elmqvist and others 2003).


Photo by Karen Conniff

Photo by C. Max Finlayson

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