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Acid sensitive catchments

Guidance on managing forests in order to minimise adverse impacts in acid-sensitive areas

View of a stream

Achieving 'Good Ecological Status' (GES) in all water bodies by 2027 is an objective of the Water Framework Directive (WFD). Acidification, a significant Reason for Failure (RFF), affects water bodies in acid-sensitive regions in the UK and Wales is particularly affected. In spite of the reduction in atmospheric pollution, acidification continues to cause adverse ecological changes in freshwaters and to damage fisheries.

Forestry and acidification

Forestry is known to have an influence on degrees of acidification, principally as a result of forest canopies' ability to capture more acid sulphur and nitrogen pollutants from the atmosphere than shorter types of vegetation. As a result, forestry in vulnerable areas needs to be managed to ensure that there is no increase in acidification or delay in returning waters to Good Ecological Status.

Standards for sustainable forest management

The UK Forestry Standard (UKFS) sets the standard for sustainable forest management. It has seven associated guidelines and the Forests and Water Guidelines (F&WG) (Forestry Commission, 2011) (UK publication in English only) require that an assessment of forestry's contribution to acidification and the recovery process be made, in catchments of water bodies that are vulnerable to acidification. This requirement was included in the 4th edition of the F&WG (2003) but no details were provided on how to implement certain aspects of the assessments.

Forestry Commission Scotland has produced these two short videos on good practice regarding water management during harvesting and cultivation activities. They demonstrate some simple ways in which operations can become compliant with the UK Forestry Standard (UKFS) Forests and Water Guidelines. The videos are made for Forest Managers and contractors, and provide a useful message for all those involved in forest operations.

Forests in sensitive catchments

In May 2014, the good practice guide, ‘Managing forests in acid sensitive catchments’, was published. This describes the measures that can be taken to minimise adverse impacts and provides a methodology for determining whether new planting, felling or restocking proposals might pose further risks to those freshwaters considered to be vulnerable.

Site impact assessments

The guide provides information for those involved and describes the component steps of catchment-based critical load and site impact assessments. The Welsh Government, Natural Resources Wales and key stakeholders were involved in consultation with the Forestry Commission throughout the process.

Clarification and simplification

Wales has taken the lead in producing an 'Implementation guide to managing forests in acid-sensitive areas,' with the aim of clarifying and simplifying the ways in which the guidance is put into practice in Wales. This guide contains information about how Natural Resources Wales can assist others as they manage their processes, in order to achieve quicker and better outcomes.

Achieving Good Ecological Status (GES)

Implementing the guidance is an important step towards ensuring GES in some of our failing upland water bodies. Natural Resources Wales has several roles to play in order to ensure proper progress is made. We work as forestry regulators, water regulators, a conservation body and as an advisor and land manager.

What are acid-sensitive areas?

To implement the guidance noted above, two categories of acid sensitivity have been identified. These are defined as ‘failing due to acidification’ and ‘at risk of failing due to acidification’.

Water bodies identified as currently ‘failing’ are shown in red on the map below. Their status has been verified as a result of actual monitoring of their acidity. The ‘at risk of failing’ water bodies, shown in yellow, have been identified, via the findings of the Welsh acidification risk assessment, as being at risk of failing due to emissions in 2027. The risk assessment combines chemical and biological data and an assessment of the environment's ability to neutralise the predicted acid pollutants.

Where are the acid-sensitive areas in Wales?

There is a map available showing where the acid sensitive water bodies are in Wales.  Relevant forestry projects will need to be assessed against the criteria in the Good Practice Guide.

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