Disfavor species that are distinctly maladapted

Urban areas will experience especially rapid changes in climatic extremes, and some species at the edges of their natural ranges may more quickly become maladapted to these conditions. In addition, urban environments are already extreme in many senses and more species may eventually become poorly adapted there. For example, species with a climate envelope that encompasses an urban area in large-scale future climate projections may not be able to tolerate conditions in more extreme urban microclimates.

Urban areas already contain a broad mixture of species that come from outside of the area. Because these species evolved in different climates, they will probably have very different tolerances to future climate conditions. In the urban landscape, fostering species transitions is less a question of whether to assist migration of species from other geographies; this is already a common occurrence. Instead, it is more about deciding when and where to incorporate species into forests and plantings in different habitats and land uses. These species could be nonnative taxa or species that are regionally native, that is, those from the same region but not currently growing at that particular location. In addition to increasing the climatic resilience of the urban landscape, urban forests could also facilitate the migration of species that will be favored under future climate to new habitats at or beyond the edges of their current range.