Favor or restore native species that are expected to be adapted to future conditions

Selecting native species already present in an urban area that are likely to do well under a range of future climate conditions can be a low-risk approach for transitioning to future climate conditions. Native species can provide important ecosystem services such as habitat for vertebrate and invertebrate species, and do not carry a risk of becoming invasive, spreading new diseases, or leading to genetic mixing. However, there may be a limited set of native species that will be able to withstand future climate conditions and also be adapted to harsh urban environments. Therefore, this approach will probably need to be balanced with other approaches to ensure sufficient biodiversity in an area.

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 (Woodall et al. 2010).