3. Towards the development of urban biodiversity

Biodiversity loss and related environmental changes are currently occurring more rapidly than at any other time in human history: many plant and animal populations are in decline, both in terms of numbers of individuals and/or geographical extent (see ). The current extinction caused by human activities is a major one: by 2050, it is estimated that 25% of species will have disappeared. Even if species extinction is part of the natural course of Earth's history, it is accelerated by at least 100 times due to human activity; E.O. Wilson even talks of 1,000 times! It takes several million years to recover biological diversity following a mass extinction, but also to regain ecosystem functioning, i.e. relations between species....