Urban trees are special. Along with grass, they are the heroes of the built environment.

They provide significant environmental, financial and social benefits and make a fundamental contribution to the well being of nearly 80 per cent of the UK population who live and work in urban areas. Poetically trees in streets and parkland may be described trees as ‘sentinels’, standing over peoples, times and landscapes like no other organism. They may be referred to as islands, even archipelagoes of life wherever they appear in the urban environment. Treekind and humankind need each other!

Database of British Trees

Why are large trees so special?

Large species trees (ie those that can attain heights of over 15 m) are the most important single elements of the green infrastructure or the "urban forest" – the trees and woodlands within and around towns and cities. They form vital elements that can match and compliment the architecture of the city in scale and create great places. You only have to walk along the tree-lined canals of Amsterdam, the boulevards of Paris, lime allées of Berlin to know that it is the large species trees that help create memorable city environments.

Large species trees are vital parts of ecosystem services with significant economic, social and environment values. By not planting more trees
future generations will miss out - and a There is no doubt that large trees are important for creating climate-proof, happy and healthy cities for the future.

So why aren't more large trees being planted instead of the small "lollipop" species seen being planted along city streets? Since the 1970s several droughts have created a situation where larger high moisture demand trees have been implicated in causing structural damage to buildings because of foundation movement where the buildings are founded on shrinkable clay soils. As well as causing building damage trees have been implicated in disrupting utility apparatus and highway infrastructure.

This perception has been exacerbated by a lack of consistency in the way that trees are managed and maintained in public and private areas. This has resulted in concerns that large trees inevitably cause tree related property damage insurance claims. Many of the finest large urban trees are a living legacy from the Victorian era and a substantial number are now nearing the end of their lives. The more recent proliferation of smaller ornamental varieties has been a response to competition for space in cities, and a misunderstanding of the problems with trees regarding issues such as structural damage and subsidence.

Keeping track of green assets of the urban environment is a worthwhile civic excercise which will involve citizens in mapping and caring for trees in public spaces.

Green maps
So-called ‘green maps’ provide means of describing (and no more than describing) the location of green areas and ‘green facilities’ in towns and cities ( Using a series of icons, a range of features are simply located on the map - from bird-watching areas to recycling plants, from wildlife corridors to litter bins.

Mental maps
Mental maps are cartographic representations of the ‘known space’ of individuals, groups or communities. They are subjective visualisations which emphasise (and are generally more accurate in the representation of) the familiar and the valued. That such maps can clearly indicate the importance placed upon green (and blue) open space was demonstrated by Soini (2001) in her review of the potential use of mental maps in Finnish landscape planning.

Google do-it-yourself maps
An example of a Google mapping database described by its makers as a virtual heritage centre of notable trees. The trees selected are individuals and in parks and streets which are notable because they carry messages in history, biology, art and poetry to produce a specific sense of place.


Biodiversity within urban trees