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Biodiversity offsetting relies on scientific hypotheses that are barely investigated. The aim of this paper is first to explore under what conditions it is possible to envisage biodiversity compensation from the perspectives of ecological science and planning policies. Two fundamental assumptions are scrutinized: the issue of substitution of a given ecological entity and the possibility to choose a given spatial and temporal reference for the dynamics of this entity. While scientific studies conducted on ecological systems have regularly emphasized the historicity of biological dynamics and the irrelevance of referring to a balance of nature, biodiversity offsetting principles rest on those out-dated assumptions. More specifically, the analysis of a practical case reveals that compensation proceeds by replacing the specificities of ecological entities by exogenous spatial and temporal framings. This process suggests that compensation should be viewed as a tool for the technoscientific reconfiguration of ecological problems. The temporal and spatial limits imposed by ecological entities are encapsulated in a political system specifically built to push back the boundaries of economic and urban development.