How will climate change affect future urban naturalistic herbaceous planting? The role of plant origin and fitness

Abstract

Climate change challenges urban planners, urban designers, landscape architecture professionals and horticulturists to pursue more sustainable vegetation in urban spaces. However, climate change also helps to free up conventional thinking, by making people come to terms with the idea that the future will not be the same as the past. Throughout the past twenty years, there has been much attention directed towards the design of structurally diverse and species-rich naturalistic vegetation for utilisation in urban areas. The aims of this study were to test whether species derived from Continental, near Mediterranean and Temperate maritime grasslands grown in designed meadow-like communities became fitter or less fit under different climate change scenarios. A community of thirty-six species from these three climatic types were chosen to represent a gradient from well-fited to poorly-fited to the current British climate. The species were chosen to share similar morphological characteristics, in terms of canopy height and structure. They were also chosen for their colourful flowers from spring to autumn, to maximise attractiveness to the public. Experiments were conducted to investigate the effects of different climate scenarios on the fitness and growth performance of these species with three watering regimes (50 % increase in precipitation; 50 % decrease in precipitation; and ambient), and two different temperature treatments (ambient and ambient plus 3 °C). The study showed that water availability and temperature have a significant impact on plant species fitness for green space under future climate change scenarios, particularly changed in concert with one another. Poorly fited species used in the study were intolerant of high levels of moisture, but increasing air temperature reduced the negative effect of additional water. Designed naturalistic plant communities of temperate and near Mediterranean plant species are a potentially sustainable element for urban landscape under future UK climate change scenarios. This study is the first to look at the effects of climate fitness on designed communities of native and non-native meadow plant species in urban landscapes.