Substantial declines in urban tree habitat predicted under climate change

Abstract

Globally, local governments are increasing investment in urban greening projects. However, there is little consideration of whether the species being planted will be resilient to climate change. We assessed the distribution of climatically suitable habitat, now and in the future, for 176 tree species native to Australia, commonly planted across Australia's Significant Urban Areas (SUAs) and currently grown by commercial nurseries.Species' occurrence records were obtained from inventories and herbaria, globally and across Australia, and combined with baseline climate data (WorldClim, 1960–1990) and six climate scenarios for 2030 and 2070 using climatic suitability models (CSMs). CSMs for each species were calibrated and projected onto baseline and future scenarios. We calculated changes in the size of climatically suitable habitat for each species across each SUA, and identified urban areas that are likely to have suitable climate for either fewer or more of our study species under future climate.By 2070, climatically suitable habitat in SUAs is predicted to decline for 73% of species assessed. For 18% of these species, climatically suitable area is predicted to be more than halved, relative to their baseline extent. Generally, for urban areas in cooler regions, climatically suitable habitat is predicted to increase. By contrast, for urban areas in warmer regions, a greater proportion of tree species may lose climatically suitable habitat. Our results highlight changing patterns of urban climatic space for commonly planted species, suggesting that local governments and the horticultural industry should take a proactive approach to identify new climate-ready species for urban plantings.