Chestnut Avenue Consultation
Explore the options and have your say
The council has launched a consultation on how to manage the declining health of an historic avenue of chestnut trees on Tooting Common. Have your say before the closing date on September 4th.
Tooting Common covers 92 hectares (221 acres) and is the largest open space in the borough. It has many diverse habitats, with its 3,300 trees forming a significant part of the landscape. The council has developed a comprehensive management and maintenance plan for the common, covering the next ten years.
The council is responsible for tens of thousands of trees, many of which require active management throughout their lifespans to ensure they remain safe and to tackle any health issues. Each year some trees require extensive pruning or complete removal as their health and structural strength is affected by age, pests or conditions like bleeding cancer or ash die back.
These issues are common across the country, both within cities and rural settings. Examples of other locations to face significant tree management issues in recent years include Barrington Court (Somerset), Parkway Avenue (Hertfordshire), Wollaton Park (Nottingham) and Whaddon Recreation Ground (Cambridgeshire).
Chestnut Avenue runs northeast from the junction of Tooting Bec Road and Dr Johnson Avenue towards Bedford Hill, it is one of four historic avenues on the common. An ‘avenue’ is a double row of trees flanking a road, path or walk, and is planted with regularly- spaced trees of similar size and age, and to best effect, is of a single species. It is the uniformity of an avenue that makes it stand out as a landscape feature.
Chestnut Avenue was first recorded on Ordnance Survey maps in 1868, making it approximately 140-150 years old. The trees would normally grow for around ten years before being planted so the original trees themselves are likely to be between 150 and 160-years old. At this age chestnuts are approaching the end of their natural lifespan.
2015 Tree Surveys
To inform the Tooting Common management plan two tree surveys were commissioned in 2015:
- Tree Condition Survey, by Treework Environment Practice: a general condition survey of all 3,300 trees on the common.
- Heritage Tree Survey, by University of East Anglia: a more detailed survey focussed on the common’s trees with significant heritage value in terms of age, species and location, including the four historic avenues.
2015 survey findings summary
Of the 77 trees in the avenue, 67 are horse chestnuts and both surveys indicated their condition is deteriorating due to a combination of age and other factors. Some have fallen over in the past, whilst others have required very significant pruning to remove weak limbs. These factors are causing the avenue to fragment and lose its value as a significant landscape feature.
The Heritage Tree Survey recorded 30 as being in ‘good’ condition with 43 described as ‘fair’ while two were ‘dead’ and two in serious decline. At that stage 20 trees were recorded as having contracted Bleeding Canker disease.
Bleeding Canker is a bacterial disease that causes cankers (bark infections) to horse chestnut trees. It affects the disruption of water and nutrients throughout the tree and if it reaches the stem it will cause the tree to die and become unstable. Bleeding Canker can also be passed from one tree to another and there is no chemical cure or control currently available. More information about the disease is available on the Forestry Commission’s and Royal Horticultural Society’s websites.
Due to various problems affecting the avenue as a whole and threats to the on-going viability of many of these trees, the Heritage Tree Survey’s authors concluded that “…serious consideration should be given to replanting of the avenue with another species.”
Chestnut Avenue – near misses
The age and health conditions affecting the trees have led to several dangerous incidents. One tree fell over in February this year despite being registered as in ‘fair’ condition in the 2015 Heritage Tree Survey.
Several other trees have dropped heavy branches without warning.
2016 in-depth Tree Condition Survey
Following the earlier survey results and safety incidents the council commissioned a more in-depth tree condition survey by Gifford Tree Services to inform this public consultation and next steps. This 2016 study focused only on the trees along Chestnut Avenue and involved a much closer examination of each tree's structural condition.
2016 survey findings summary
This survey shows the avenue is in significantly worse condition than the earlier Heritage Tree Survey study suggested. Of the horse chestnut trees surveyed, three were recorded as dead (including the one which fell), 26 were recorded as “poor”, 29 as “fair” and four as “good”. The difference between the surveys is attributed to the closer examination of the trees’ structural condition.
Short term measures
The consultant which undertook the 2016 in-depth survey has recommended a programme of work for which the council considers necessary to reduce the risk of another dangerous incident:
- The removal of five trees, including two immediately.
- Due to structural weaknesses, a further 26 trees require extensive works. This entails substantial pruning to reduce the height of the majority of the larger trees to prevent the breakage or collapse of large limbs and will need to be repeated at regular intervals in future because the underlying weaknesses will increase with time.
Preferred long term options for consultation
There are different ways the council could manage the declining health of Chestnut Avenue and we want to hear residents’ and stakeholders’ views on these different options. The feedback received will be taken into account when councillors make a final decision, alongside the views of tree experts within the Parks Service and the evidence compiled within the three independent tree surveys.
Maintain the existing horse chestnuts, allow them to decline and die whilst protecting public safety. As some trees will need to be removed and many others will need to be extensively pollarded, the result will be an uneven row of trees.
This will lead to gradual loss of trees and new trees can be planted as trees are lost, but these will all be of different ages and grow at different rates. There will be a continual cycle of loss and replacement - the avenue will not recover its former appearance of evenness and uniformity.
(The illustrative images below are not to scale).
Remove all the trees along the avenue and do not replant. This would remove the safety risk associated with an aging and declining avenue of trees, leaving a wide open space in place of the existing landscape feature.
(The illustrative image below is not to scale).
Replace the horse chestnuts with an avenue of new trees. The removal of the current avenue and the planting of the replacement avenue would be carried out at the same time. It would take approximately 20 to 30 years for the trees to reach maturity.
By removing all the existing trees, the new trees can grow unimpeded and will have all the light, water and air they need, and will therefore reach maturity more rapidly. This is the quickest way to establish a new avenue landscape feature for the common.
Horse chestnut trees have relatively short lifespans in tree terms and they are not native to Britain. They are subject to a number of pests and diseases and they do not support as much biodiversity as other trees. The recommended tree for a new avenue would be the small leafed lime. This species lives longer, is more durable, and by being a native British tree, will support greater biodiversity.
(The illustrative images below are not to scale).
The following option is viable, but very unlikely to result in a new avenue of evenly sized, evenly spaced and consistently healthy trees on Tooting Common. As such it is not included in the preferred options for consultation, but nor has it been ruled out completely.
Plant a new avenue of young trees in the spaces between the existing trees:
This is not a preferred option because:
- Gaps between existing trees are uneven and there is insufficient space to plant an even row of trees that would form an avenue in future years.
- Most of the new trees would be located within the dense shade of the existing trees’ canopies and within the existing trees’ root network. It is very unlikely they would all successfully establish themselves and grow into a healthy and symmetrical avenue in these conditions.
- To improve the growing environment some of the the existing mature trees would need to be felled and others would be heavily cut back but this would affect their health, diminish their individual appearance and diminish the overall landscape value of the avenue.
The following options are not considered viable and have been ruled out:
1) Do nothing:
This option has been ruled out on in light of recent dangerous incidents and the on-going risk to the public.
It is clear that significant works to these trees are required to ensure the common provides a safe environment for local people.
2) Plant a new avenue inside the existing lines of trees:
There is insufficient space between the existing trees and the shared cycle/footpath for new trees to grow.
New trees would be located within the shade of the existing trees’ canopies and within the existing trees’ root network. It is very unlikely they would successfully establish themselves and grow into a healthy and symmetrical avenue in these conditions.
To improve the growing environment the existing trees could be heavily cut back but this would affect their health, diminish their individual appearance and undermine the overall landscape value of the avenue for many years.
3) Plant a new avenue outside the existing lines of trees:
There are physical barriers to planting a full length avenue outside the existing tree line, including the playground, tennis courts and lake. As such the new line of trees would be incomplete and asymmetrical.
The new trees could not be successfully planted between the existing physical barriers and the existing trees as they would be shaded and within the established root networks. As such they would be unlikely to have the light, water and nutrients they need for healthy growth. It is unlikely they would grow evenly to form a symmetrical avenue in these conditions.
To improve the growing environment the old trees could be heavily cut back but this would affect their health, diminish their individual appearance and undermine the overall landscape value of the avenue for many years to come.
We want to understand local residents views on the challenges facing these trees and the options outlined above. To have your say please complete the on-line questionnaire before the closing date September 4, 2016.