Qualitative assessment

Food production

The proposed scheme is likely to result in an overall loss of agricultural land. Notably, there is a loss of almost 6ha of general cropping habitat (non-cereal crop habitat and temporary grass and clover leys), and some loss of cereal crop habitat. The creation of modified grassland goes someway to counter this impact, however there would likely be an overall net loss for this ecosystem service. It is likely that the value of food production varies across the areas of impacted agricultural land more than it was possible to capture within the quantitative assessment. Nonetheless, it is considered that there will be a potentially moderate adverse impact on this ecosystem service.

Potential moderate adverse ecosystem service impact

Timber production

It is anticipated the proposed scheme will likely result in a loss of timber production. This is due to areas currently used for felling potentially being taken out of production to enable mitigation planting. There are two key areas within the scheme boundary that have active felling licences. The Dalpowie plantation is expected to be taken out of timber production prior to construction of the proposed scheme, therefore there is considered to be no impact on this area. Another area to the south of the proposed scheme (Muir of Thorn and Gelly Wood) also has active felling licences, and this area is expected to be used for mitigation planting. It is assumed that in this case, felling will no longer occur, therefore reducing this benefit. There are however uncertainties around how much are this area will be required for planting and therefore it is expected the impacts will be moderately adverse.

Potential moderate adverse ecosystem service impact

Air pollutant removal

The proposed scheme encompasses a significant area of woodland, which plays a vital role in mitigating the impacts of air pollution, particularly in comparison to other habitats such as grassland, agricultural land, and developed areas. However, the construction of the scheme will lead to an overall loss of coniferous woodland which is one of the most effective natural assets for removing atmospheric pollutants.

As a result of the habitat changes, this ecosystem service will likely be diminished both during construction and operation of the proposed scheme. Although the proposed scheme creates some woodland and grassland habitat areas, the benefits of this will not be immediately realised, as newly planted areas will require time to establish. Given the rural setting of the project, where background air pollution levels are low and expected to remain low, the overall decline in air pollutant removal services is anticipated to be moderately adverse.

Potential moderate adverse ecosystem service impact

Carbon reduction

The proposed scheme covers a significant area of woodland as well as areas of heathland, grassland and arable land which all have increased carbon stocks when compared with developed, sealed surfaces. Carbon storage (stocks) is expected to decrease overall with the introduction of the proposed scheme due to losses of vegetation carbon as a result of clearance and soil carbon associated with disturbance during construction and land use changes. This is largely due to the initial loss of soil carbon and vegetation carbon during the construction phase and the subsequent time for newly created habitats to replenish soil carbon stocks during the operational phase. There are anticipated to be some benefits to carbon reduction during the operational phase, notably associated with the planting of parcels of compensatory woodland habitat. The average age of existing woodland stands relevant to the proposed scheme is assumed to be approximately 40 years. The Woodland Carbon Code (WCC) states that carbon sequestration in trees typically peaks between years 16 and 25 of a tree's life, after which this tails off with a slowing growth rate. Consequently, the replacement of existing woodland parcels with new planting is expected to provide a net benefit to carbon drawdown. However, such gains are not expected to outweigh the initial losses of soil and vegetation carbon during construction and thus a potentially substantial adverse impact on this ecosystem service is anticipated.

It should be noted that the carbon fluxes described above are discussed in further detail in Section 6.5.

Potential moderate adverse ecosystem service impact

Flood regulation

Within the NCA boundary the baseline habitat includes a small area of blanket bog and a substantial area of woodland and grassland. These natural assets are effective at intercepting rainfall and slowing flood waters compared to agricultural and developed land. It is likely that there would be a reduction in this ecosystem service during construction and the period immediately following. This is due to an initial loss of high value habitat (conifer woodland), and whilst an overall increase in other types of woodland and grassland is expected as a result of the proposed scheme, there will be delays until benefits will be realised, due to the time taken to establish newly created habitats. Overall, there is likely to be a reduction in this service as a result of the proposed scheme, mitigated to an extent by the creation of new woodland and grassland areas.

Potential moderate adverse ecosystem service impact

Pollination

The proposed scheme is anticipated to result in both gains and losses of habitat types that are important to support pollinator species. The most significant of these include a loss of coniferous woodland and overall gains in both lowland mixed deciduous woodland and neutral grassland. Both woodland and grassland habitat types are particularly high value for supporting pollinators, whilst the coniferous woodlands scores poorly, meaning there is an overall gain in habitats which are likely to be more beneficial for pollinator species. The overall impacts on this ecosystem service are expected to be a potential moderate positive impact.

Potential moderate positive ecosystem service impact

Soil erosion protection

Soil erosion protection provided by habitats via vegetation can reduce the risk of landslips and maintain ground stability. Geotechnical hazards have been identified along the proposed scheme, including areas where landslides have occurred historically as well as potential rock slope hazards. Habitat changes are anticipated which will decrease vegetation cover along the proposed scheme; however, replacement habitats are planned (note. the extent of replacement habitats has not been confirmed at the time of writing, therefore has not been considered in this assessment). Earthworks are proposed in areas of existing geotechnical hazards and there is potential for the failure of both natural and engineered slopes if hazards are not mitigated through implementation of good practice measures and design. Geotechnical hazards are to be considered at the proposed scheme specimen design and subsequent detailed design stages. As soil erosion protection will be provided by replacement habitats and geotechnical hazards are to be mitigated through good practice and design, a limited/no ecosystem service impact is expected for the proposed scheme.

Limited ecosystem service impact expected

Education

The Dunkeld area is frequented by universities in Scotland as a field trip site to educate students on structural geology and is recommended as an excursion by Geological Societies. There is potential for the proposed scheme to create new areas of geological interest through exposure of rock for new road cuttings, including areas which could be related to recognised GCR (Geological Conservation Review) Sites. Three areas of cut have been identified as potentially exposing bedrock features of interest which could enhance the existing educational visits already carried out in the Dunkeld area. This is dependent on these areas of road cut being made accessible to the public and the presence of unique rock features. Due to the increase in educational visits, a potentially moderate positive ecosystem service impact is anticipated for the proposed scheme.

Potential moderate positive ecosystem service impact

Landscape and amenity

The area of the proposed scheme is currently characterised by the varied landscape of the Tay Valley, with the River Tay meandering through the glen and views of the highlands further north. Extensive areas of woodland and forest cover the surrounding area, and even where managed, form a perception of a natural setting. Landscape designations across the proposed scheme include the River Tay (Dunkeld) National Scenic Area (NSA), Murthly Castle Garden and Designated Landscape (GDL), The Hermitage GDL, Dunkeld House GDL, Tay forest park, Dunkeld Conservation Area, and the Birnam Conservation Area.

There is potential for the proposed scheme to result in adverse impacts to the local community, with the consultation process raising concerns arounds loss of woodland (resulting in loss of biodiversity), risk of windthrow for the remaining woodland, loss of screening vegetation, encroachment of the proposed scheme on the footprint of existing gardens, and effects on the River Tay NSA area’s beauty and tourism. All of these impacts would likely reduce the quality of the surrounding landscape (although some of it would be temporary due to construction), which could ultimately reduce the benefits to both local communities and people visiting.

Key, temporary impacts from construction that are likely to negatively impact landscape include the removal of roadside woodland and scrub, an increase in machinery (excavators and plant) and haulage routes, additional exposed bare earth, structures, earthworks and road surfacing works, temporary soil storage and stockpiles of construction material, and lighting associated with nighttime working and site accommodation. The most significant adverse impacts are expected where major structures and junctions and associated earthworks are being constructed. Key operational impacts that are likely to have more permanent negative impacts on landscape include the operation of the additional carriageways, junctions, and side roads, the addition of associated infrastructure (signage, cameras, barriers, fencing, lighting etc.), a change in the perception of landscape character or landscape/townscape, loss of woodland, alteration of vegetation patterns and field patterns due to tree loss, changes appearance of landform along the road corridor, presence of new bridge structures, and increased visual influence of traffic on the surrounding landscape. In addition, it is anticipated the proposed scheme will have a visual impact, with up to 73 buildings and 35 outdoor locations impacted during construction, and during operation, initially 43 buildings and 35 outdoor locations impacts, reducing to three buildings and five outdoor locations impacts after 15 years (due to the establishment of vegetation planted). All of these impacts influence the natural beauty of the area, which many people in the local community and visitors will benefit from.

There are mitigation measures planned as part of the proposed scheme. These include earthworks proposals that minimise the impact of cutting and embankment slopes, the incorporation of Sustainable Urban Drainage Systems (SUDS), returning compensatory flood storage areas to former land cover (where appropriate), use of earth bunding to provide noise barriers, use of natural stone cladding etc. on structures, retaining existing and woodland where possible and planting to replace trees lost, use of native species to enhance biodiversity, and grass and wildflower seeding. All of these measures would minimise the negative impacts on the scheme, and where enhancements to the natural environment are included (e.g., woodland planting, wildflower planting etc.) this would have natural capital benefits for the local community and visitors. In addition, some of these mitigation measures may support additional ecosystem services, for example the planting of native species may support pollinators, and woodland planting may support flood regulation, air pollutant removal, and carbon sequestration and storage.

Overall, the landscape and visual assessments concluded there would be some significant (large) impacts to landscape on the year of opening, specifically on the Strath Tay: Lower Glen Local Landscape Character Area. This would reduce following establishment of replacement planting; however, this is still considered significant (moderate). In other areas, the initial impacts are likely to be moderate, however following the establishment of planting, these would reduce to not significant. It is therefore concluded that from a natural capital perspective, there is likely to be limited ecosystem service impact. Whilst some of the proposed mitigation measures may have positive impacts to the local community and visitors, there would likely be negative impacts during construction and until any vegetation planted is established.

Limited ecosystem service impact expected

Recreation

The proposed scheme is not expected to have any tangible impacts on the amenity of any green spaces dedicated to outdoor recreation. However, there are various path creation and enhancement measures planned as part of the proposed scheme, some of which are anticipated to have a tangible, positive impact on the recreational experience of walkers, wheelers, cyclists, and horse-riders (referred to as WCH) of two ‘Outdoor Access Areas’ (OAAs) (as defined within the DMRB Stage 3 EIAR Chapter 17 (Population – Accessibility)). The relevant path creation and enhancement measures are shown in APPENDIX B. In summary, the path enhancement and creation measures in Appendices B1 and B2 should improve accessibility to the Hermitage from Dunkeld for WCH and create a new circular route with enhanced accessibility around the River Braan (Inver) OAA. Meanwhile the creation of the new path shown in Appendix B3 should connect up two popular routes for walkers, the Ring Wood area and the Murthly Riverside Path, creating a single, cohesive route along the banks of the Tay. This could potentially notably improve the River Tay Way walking route.

Potential substantial positive ecosystem service impact

Volunteering

Environmental volunteering offers a variety of personal and social benefits, including physical activity, social connections, skill development, and preparation for employment. Additionally, collecting data on volunteer involvement and highlighting the positive impact of volunteer opportunities can be instrumental in securing financial support from donors. The proposed scheme has the potential to support volunteering hours for local environmental groups to increase their outreach. These groups carry out activities such as ecological surveys and tree planting. If this were to be supported, a potential moderate positive ecosystem service impact is anticipated for the proposed scheme.

Potential moderate positive ecosystem service impact