Wealden District Council

Ashdown Forest Monitoring FAQs

Large parts of Ashdown Forest (2,729 hectares) are designated as a Special Area of Conservation (SAC). The SAC status was awarded because Ashdown Forest contains one of the largest single continuous blocks of lowland heath in south-east England. The SAC designation recognises the special nature of the vegetation found within Ashdown Forest, namely European dry heaths and North Atlantic wet heath and affords it legal protection by the Conservation of Habitats and Species Regulations 2012 (as amended) which transposes the requirements of the European Habitats Directive (92/43/EEC).

Wealden District Council is required to consider the effects of new developments on the integrity of the SAC. This includes considering the effect of new development on the SAC with regards to an increase in traffic that may result from such development. This is on the basis that excess nitrogen or an increase in nitrogen from more cars on the road or an increase in car journeys across the forest may result in damage to the protected species or a net decrease of species or habitat cover.

The information currently available on this subject suggests that there is an existing problem concerning nitrogen and the protected heathland habitats within the Ashdown Forest. However, the contribution of traffic emissions to effects on the Ashdown Forest SAC is not currently known. Wealden District Council has therefore commissioned Ecus Ltd to investigate the effects of nitrogen from road traffic. This includes air quality monitoring and vegetation surveys to gain a greater scientific understanding of the effects of air pollutants on the protected heathland species, which will be greatest within 200m of the road. If significant effects are identified, then this will inform the development of planning policies and whether certain development proposals may take place now or in the future.

There are a number of FAQ's provided below and an Ashdown Forest air quality and vegetation monitoring leaflet (pdf) is available to download.

Why is it necessary to monitor air quality in Ashdown Forest?

Air pollutants not only affect human health, they can also cause harm to plants, habitats and ecosystems. Nitrogen is an essential nutrient for plant growth. However, inputs of excess nitrogen into an ecosystem can result in detrimental effects. For example, excess nitrogen can cause a bloom of fast growing plants so that other plants are starved of nutrients and light and eventually die. The heathland habitat within the SAC requires a low nitrogen input to maintain the species of interest at Ashdown Forest.

While there are many sources contributing to nitrogen, an important one is air pollution. Nitrogen in the atmosphere comes from many different sources, both local and more distant. However, road traffic is the most important local source where road transport emits nitrogen from fuel combustion.

What air pollutants will be measured?

Measurements will be made of a number of nitrogen species in the atmosphere. This will include the gases: nitrogen dioxide, nitrogen oxides, ammonia and nitric acid, as well as nitrogen associated with airborne particles, in particular ammonium nitrate. These gases and pollutants are either deposited directly to the surface of vegetation or converted to other less common nitrogen compounds in the atmosphere which are also then deposited.

What type of air pollution monitoring equipment will be used?

There is an automatic monitor in an air conditioned housing measuring nitrogen dioxide, nitrogen oxides and ammonia. There are samplers that pump air through tubes that absorb ammonia, nitric acid, and ammonium nitrate particles. Finally there are diffusion samplers used to measure nitrogen dioxide and ammonia. These are small plastic tubes that are fixed to posts. The bottom of the tube is open, while a specially coated grid under the plastic cap at the top of the tube absorbs the pollutant. The tubes are replaced regularly and returned to the laboratory for analysis.

When will the air quality monitoring equipment be placed in the Ashdown Forest?

The first monitors were put out in August 2014. All of the other monitors were installed in October and November 2014.

Who will be undertaking the air quality monitoring work?

The air quality monitoring will be the responsibility of Air Quality Consultants Ltd. Regular visits will be made to the sites by WeCare4Air Ltd. to change the samplers. The automatic monitors will be serviced by Enviro Technology Services plc, and independently checked twice a year by Ricardo-AEA.

Why is it necessary to monitor ecology in Ashdown Forest?

Nitrogen deposition is increasingly recognised as being one of the most significant threats to biodiversity in Europe. The consequences of nitrogen deposition can have detrimental effects on certain plant species such as those present at Ashdown Forest. The ability for species to withstand the effects caused by nitrogen may differ from place to place and may depend on a range of different factors. For this reason, it is important to monitor the vegetation and species at Ashdown Forest to learn about the condition of the protected species and whether the health of the heathland habitat is changing over time. The purpose of vegetation monitoring is to therefore assess the effects and potential effects of nitrogen on the protected heathland species.

What will the vegetation monitoring involve and how intrusive is the vegetation monitoring?

A small number of transects will be set up throughout Ashdown forest, stretching from a road into the heathland, with a number of quadrats (an area of ground of 2 x 2m) selected along each transect. A survey of the vegetation within each quadrat will be undertaken on a yearly basis. The most intrusive aspect will be installing small ground markers to mark the quadrats, to ensure that the same locations are surveyed each year. Ground markers comprise metal pegs that are set into the ground, at or just below ground level. Two corners of each quadrat will be marked with pegs. This is a standard survey technique and approved by the Conservators of Ashdown Forest and Natural England. Survey work will require a small team of surveyors on the ground for up to four weeks each year.

What else is involved in the ecological monitoring?

In addition to transect monitoring, vegetation and soil samples will be taken for chemical analysis to determine the level of nitrogen present. Soil and vegetation sampling will be undertaken every year for the first three years of the study.

Will there be ecological survey equipment left on site?

The only permanent ecological monitoring equipment left on site will be the ground markers to identify the quadrat locations and these will not be visible to the public due to the height of the vegetation.

Who will be undertaking the ecological monitoring work?

Experienced ecologists from Ecus Ltd will be undertaking the vegetation survey work.

How long will the monitoring and surveying go on for?

To provide reliable data it will be necessary to carry out the monitoring for a number of years. The initial programme of monitoring and assessment runs for four years. A decision will then be taken as to whether it should be continued.

When will the data be available?

The monitoring began in the summer of 2014. It is necessary to monitor for at least a year to obtain reliable data. The first air pollution data should be available after the summer of 2015. However, it will be longer before a full understanding of the effects on vegetation can be determined and several years of monitoring may be required before any conclusion can be made. A report will be provided to the Council following 3 years of monitoring.

What will the results be used for?

The air pollution monitoring will be used, in conjunction with the results from a detailed numerical dispersion model, to predict the exposure of the vegetation in the SAC to potentially harmful effects from traffic emissions. The model will also allow impacts of future changes in traffic flows to be predicted.

The results of the vegetation surveys will be used in conjunction with the air pollution results to establish the extent to which the SAC is being harmed by road traffic emissions.

The results of this work will be used to assist the Council in planning decisions and the production of future planning policies relating to the level of development that is acceptable within the District when considering the duty imposed on the Council under the Habitats Regulations / Directive to consider the effect of development on the Ashdown Forest SAC.

Can aircraft emissions also result in a detrimental effect on the protected heathland habitat?

A large number of scientific research studies have shown that, once aircraft reach altitudes of more than a few hundred metres, which usually happens within a few hundred metres from the airport boundary, their effect on ground level air pollution concentrations becomes negligible. This is because the pollution which is emitted becomes dispersed and diluted into high-altitude air, rather than being brought down to the ground. Emissions at height will have an incremental effect on general background pollution levels, but no measurable effect on ground level concentrations or deposition rates.

Contact the Planning Policy Team