The plant species for the parks of the future have to be planned with a long-term, integrated approach, because plants – especially trees – have long life-spans and take a long time to develop. The pressure on parks will increase as the parks become ever smaller and more built-up and subject to ever more wear and tear. Plants are also needed for new kinds of uses, such as for storm water areas and for the greening of roofs and walls. Climate change may increase the range of plants available, but it can also increase the risk of introducing invasive alien species and plant diseases and pests. The future can be secured only by planting the greatest possible number of different plant species, and this is particularly important when choosing trees.