The council says the cause of the damage is nitrogen emissions from motor vehicles, and other sources, and “it is clear that additional housing will increase nitrogen deposition alongside roads close to Ashdown Forest Special Area of Conservation”.
The council is proposing action through its Local Plan, currently being prepared, as it considers the future threat to the forest.
One is to reduce the number of homes included in its Local Plan. The other is to introduce compensation measures before any new development in the district, involving increased vehicle use, can go ahead.
The council says, in document of frequently asked questions, produced this month:
“The evidence is clear that additional housing will increase nitrogen deposition alongside roads close to Ashdown Forest Special Area of Conservation.
“The amount of nitrogen deposited depends on the amount and location of housing.”
The council says a range of mitigation measures are already in place on the forest, and others have been discussed including traffic speed restrictions, introducing tolls, restricting categories of vehicles and options for tunnels in the forest.
It adds: “For a variety of reasons these additional measures would not produce significant improvements, because they are either not practical or not economically viable.
“The council continues to explore the issues but our current view is that compensation measures are required.”
The council’s favoured option is for comparable habitat to be provided which can be restored to lowland heath so compensating for the roadside areas affected by nitrogen deposition.
It says any new planning applications within the district will need to show they will not generate any additional vehicle movements in order to be considered for approval.
This will apply across the district, south as well as north.
The council says: “As a planning authority we cannot guarantee that new vehicle movements, resulting from a development in the district will not involve routes near, or through, the Ashdown Forest, and lead to consequent environmental damage.
“Once appropriate compensation measures are in place, new development will be possible up to the level set out in the plan.”
The proposal is to reduce the number of homes in the new Local Plan – which would run until 2028 – to about 11,500 homes from nearly 20,000 contained in a consultation document.
Of the 11,500 homes nearly 7,400 already have planning permission or been completed.
The results of nitrogen deposition monitoring and the action Wealden Council is taking have been shared with other planning authorities with areas close to Ashdown Forest.
Wealden says local authorities have a duty to cooperate on local plan issues and they have informed Mid Sussex, Tunbridge Wells, Eastbourne, Rother and Lewes councils and South Downs National Park.
Read the full document of frequently asked questions on the Wealden website. A link is within the section Wealden Local Plan Update – May 2017.
The Local Plan is being updated to take into account planning permissions granted after September 30, 2015, and the emerging evidence base.
It is due to goe before the Local Plan sub-committee, Joint Planning Committee North and South and Full Council later this year.
If approved, it will go out for formal representations. Those representations will be considered and the document will be submitted to the Planning Inspector for examination.