Trees and the Public Realm - Westminster City Council

Trees and the Public Realm (Draft) Page 41
8. SUSTAINABILITY CONSIDERATIONS
105. In addition to the matters raised already in this document, it is also important to
consider the role trees play in the ‘green agenda’ and the increasingly pressing issue of
climate change. Within the City of Westminster there are many areas which have clear
deficiencies in open space and greenery, as shown in the map over the page 9 . Whilst
some of these areas may not be suitable to accommodate trees, there are a number of
opportunities for other interventions throughout the borough to address these
sustainability issues.
Biodiversity
106. Native trees are best for biodiversity as they generally support a wider range of species
than introduced trees. Large and older trees will support more plant and animal species
than small or young trees of the same species. Veteran trees 10 are particularly important
for biodiversity as they have the potential for bat and bird roosts owing to cracks and
holes that develop in the tree from decay over time.
107. Our parks, open spaces and cemeteries offer the greatest opportunity for the planting
of native species, but where possible and without conflict to other design intentions,
native trees should also be considered for street tree planting.
Climate Change
108. The maritime climate of the British Isles is historically characterised by the absence of
extremes of heat and cold. Our cities therefore have been climatically equitable places
in which to live and work. However there is a general consensus amongst experts that
temperatures will increase, summers will be hotter and drier, winters will be warmer and
wetter, and there will be an increase in the number of storms and floods. Recent reports
have recognised the role of trees in combating these trends 11 .
109. Trees in enclosed pits may struggle in future to find sufficient water to remain healthy,
and certain species, such as beech, birch and ash may not cope well with these
climatic changes.
9 This map has been extracted from council’s Open Space Strategy. Further details are provided in
Appendix E.
10 Veteran trees are trees which, because of their great age, size or condition, are of exceptional value
culturally, in the landscape, or for wildlife.
11 More details on the Mayor of London’s 2009 environmental programme are provided in Appendix E.