Reflections on urban flora and climate change

Abstract

Based on the experience obtained at the Botanical Garden of Barcelona over the last twenty-five years, some aspects are highlighted that could be useful in the selection of plants in Mediterranean urban environments in the light of the uncertainties posed by climate change. Plants in the city provide numerous ecosystem services and, in climates with hot summers, they are especially useful for moderating heat peaks. Most species on street-tree alignments are allochthonous or of hybrid origin. In Barcelona, only 3% are Mediterranean forest trees. Previous studies showed that the best adapted species are deciduous or semi-deciduous trees that are naturally distributed in temperate or subtropical regions marked by summer rainfall, with compound leaves, naked or hypsophyllary leaf buds, anemochore seed dispersal and entomophilous pollination. However, vigilance should be exercised in the introduction of new, little-known plants because of the risk of introducing invasive species. As regards other plants, the aggregation of those that in nature form natural communities can be a good guideline for designing resilient and harmonious gardens.