With 66% of the world’s population predicted to live in cities by 2050, the challenge of reconciling urban growth with biodiversity conservation demands attention.
Although the environment is altered by urbanization, there is potential for cities to support a great deal of biodiversity [Collas 2017: 1866].
This study shows that urban growth and biodiversity enhancement are compatible by increasing housing density (in order to reduce total surface area of development) while restoring ecosystems on remaining green space through woodlot plantings. The study was conducted in Cambridge, England, whose population is expected to grow by 22% between 2011 and 2031, and where “current green space supports relatively few trees” [Collas 2017: 54]. Green space could be maximized and restored to woodlots while additional high-density housing could accommodate the expected population growth.
Furthermore, only 2% of green space (i.e. ≥30 ha) is needed for conversion to woodlot to increase the native tree population size in Cambridge while also increasing high-density housing. This is compared to an alternative growth scenario, where new development is low-density and inhabitants are expected to plant trees in their relatively large yards, while no city-led green space ecosystem restoration occurs.
In conclusion, the authors offer this:
For other cities in the UK and across Europe, which have generally long been cleared of natural habitat, restoration in parallel with the expansion of higher density housing would appear to offer greatest scope for accommodating population growth at least cost to nature. This would require policy and economic incentives to directly link high-intensity human land-use to large-scale restoration [Collas 2017: 1871].
Collas, Lydia, et al., 2017, Urban development, land sharing and land sparing: the importance of considering restoration, Journal of Applied Ecology 54, https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12908.