Trees in our streets improve air quality, provide beneficial micro-climate, enhance property values and aesthetics, attenuate storm water, conserve energy, reduce noise pollution, provide wildlife habitat, and have a positive effect on physical and mental human health.
There’s no denying that trees can cause problems in the built environment. Their roots can disturb pavements, roads or underground services, they can be too close to buildings undermining foundations or blocking sunlight and views. Fallen trees or limbs in storm events can block roads and railway lines, they sometimes damage property and do sometimes kill people. Perhaps it’s no wonder that trees are increasingly seen as a liability.
Street trees should be managed for their benefits however, as well as for risk and hazard. I’m often horrified at the sight of a street tree, stripped of its limbs and decency – all in the interests of health and safety. There is a cultural obsession in our towns and cities in trying to remove as much risk as possible but this can be detrimental to tree health. This is important because poor health is linked to tree stress and in turn its susceptibility to tree pathogens; and we know that threats from tree pests and diseases are ever-increasing. Furthermore, a decline in tree health will more likely lead to a tree that it is prone to shedding limbs or uprooting: over-pruning a tree is likely to be worse than not pruning at all.
The larger the tree, the greater the benefits. We need more large trees in our streets, and for these to be lightly maintained for both their and our benefit. Urban foresters and town planners will need to challenge perceived wisdom in tree management, as we aim to make our towns and cities fit for the 21st Century. Ultimately, we need to start looking at the entire street tree resource in any town or city as an Urban Forest, and plan to deliver all the benefits listed above.