Throughout the urban landscape, trees make up
important elements of the overall green infrastructure – providing us with
numerous ecosystem services of which we depend on as a community. Trees also help us orientate and relate to
the spatial context around us, creating an architectural transition from bold
and often large scale buildings down to ground level as experienced by man. In
the past, city trees would mirror the prosperity and cultural affluence of a
society and as such, trees were planted mainly for beautification and
aesthetics. Today, we know that the qualities of the urban tree stock reach
beyond these concepts. With current challenges of climate change and rapid
urbanization, the focus on trees has shifted towards many of the regulating
ecosystem services much needed in the urban landscape. The role of urban trees
today and in the future will thus be to help mitigate the urban heat island
effect, shade buildings and thus reducing energy consumption, slow down surface
runoff, act as noise filters, and purify the air through capturing particulate
matter, carbon dioxide, ozone and other air pollutants originating from traffic
and industrial activities. Whilst such services are generally measurable, urban
trees also provide for more boundless qualities increasing recreation, health
and wellbeing for the community – and yes, aesthetics too.
However, in order to plan and
subsequently secure a sustainable succession and development of our urban
trees, we need to reach a better understanding and increase our knowledge of
how different species respond in different situations – all in order to
provide for different ecosystem services.
With the limited space in towns and cities, and with current and future change
occurring in climate and pattern of urbanization, multi-functionality and
reliable plant material will become increasingly important. As such we need to
begin a new discourse where focus is directed towards what kind of tree species
we are using and from which cultivar the species originate? For the urban tree
planner and landscape professional, a better understanding of the indigenous
background and strategy of different tree species will in the end provide a
robust platform from which decisions can be made in order to plan, design, and
manage a sustainable urban landscape. With examples of how to link biological tree
strategies as found in nature to the current urban context the presentation
will provide some illustrative examples from eastern Europe, China, and the
U.S. and how knowledge from nature will help in the selection of site adapted
species choice for different urban environments.