Two new official publications potentially strengthen tree managers’ ability to protect and enhance urban and protected tree stocks, reinforcing broader policy aims that recognise their many benefits. The Government announced in March that new developments must provide "biodiversity net gain", and said this will feature in the Environment Bill, still before Parliament.
The Ministry of Housing, Communities & Local Government’s guidance on the natural environment, updated on 21 July, states only that planning conditions or obligations "can, in appropriate circumstances, be used to require that a planning permission provides for works that will measurably increase biodiversity". These measures need not be on the development site itself and can include providing street trees locally as well as other green infrastructure features such as green roofs, green walls or sustainable drainage systems.
In such cases though, the developer will need to show that such measures "will lead to genuine and demonstrable gains for biodiversity", and therefore need to be "supported by the appropriate scientific expertise and local wildlife knowledge". Official guidance on biodiversity offsetting is available from Defra.
Biodiversity is, of course, not the only reason to plant and maintain urban trees. The guidance lists their other benefits as "encouraging walking and enhanced physical and mental health; contributing to local environmental character and distinctiveness; reducing noise and excessive heat; and supporting sustainable drainage", adding that "trees of the right species and age profile are essential".
On the practicalities of planting and maintaining street trees in particular, it points out: "The interaction of trees and tree roots with built infrastructure, transport networks, buildings and utility services is complex and requires detailed interdisciplinary co-operation, with expert arboricultural or forestry advice. The selection of street trees needs to consider which species will best suit the highway environment in the long term, including associated infrastructure and utilities."
Coinciding with this, the Forestry Commission’s newly published "Highway tree management: operations note 51" lists a number of both engineered and tree maintenance solutions that can be deployed to maintain highway trees. All of these "will require the co-ordinated response and guidance of an experienced and qualified arboriculturist working closely with an experienced highway engineer".
Yet this need not be difficult, as it points out: "There is a wealth of technical advice and information available across the relevant sectors that provide practical and comparatively low-cost methods of permitting highly valued trees to exist within a well maintained and modern inclusive highway."
A modern priority
One of the most marked recent changes in guidance on tree-related planning issues relates to ancient woodland and ancient or veteran trees, which since last year have the highest possible protection from development under the revised National Planning Policy Framework.
Natural England’s ancient woodland inventory can help to establish whether a given wood meets this designation, the guidance notes. The Forestry Commission and Natural England, meanwhile, publish standing advice on what constitutes ancient or veteran trees, and the Woodland Trust maintains an inventory of known ancient trees.
Planners "need to consider both the direct and indirect impacts on ancient woodland and ancient or veteran trees when assessing development proposals and the scope for avoiding or mitigating adverse impacts", the guidance adds. "Their existing condition is not something that ought to affect the local planning authority’s consideration of such proposals." The test of "wholly exceptional reasons" for removing or compromising such trees or woodland should be met before any compensation measures can be considered, it states.
On new woodlands, including designated community forests as well as the National Forest in central England, the guidance reads: "Planning policies and decisions need to consider the extent and type of woodland planting necessary to ensure that the new development will contribute to the creation and emerging character of forests." In its guide for developers published last year, the National Forest Company set area thresholds of 20% "forest green infrastructure" for smaller developments and 30% for larger ones.
Welcoming the two documents, Sharon Hosegood, chartered arboriculturist and vice-president of the Institute of Chartered Foresters, says: "Our members already work with developers, councils and planners to make sure they have the best advice, not just when it comes to planting but also selecting the right species of trees for the location.
"With planting more trees at the forefront of the current political agenda, the role of chartered arboriculturists has never been so important."
On the Forestry Commission guidance, she adds: "Critically, it makes clear that decisions about tree care must be a collaboration between a suitably qualified and experienced arboriculturist working closely with a highway engineer."