Slopes and valleys with woodland

Overall vulnerability

Feature(s) assessed:

• Slopes and valleys with woodland
• Wooded narrow steep sided cloughs
• Meandering pastoral river valleys defined by woodland

Special qualities:

• Beautiful views created by contrasting landscapes and dramatic geology

Feature description:

Areas of woodland on slopes or within valleys and cloughs can be found throughout the PDNP from small pockets to large tracts of wooded land.

In the South West Peak there are significant woodlands, particularly above Macclesfield and the Goyt Valley. Within the Dark Peak there are a number of woodlands including large areas of conifer plantation in the Derwent Valley. Around the moorland slopes and cloughs any woodland is smaller and more scattered in nature. For slopes and valleys with woodland in the White Peak please see the Limestone Dales feature.

Slopes and valleys with woodland provide a contrast to more open landscape types in the PDNP, such as heather moorland or pastoral farmland.

How vulnerable are slopes and valleys with woodland?

Slopes and valleys with woodland in the PDNP have been rated ‘high’ on our vulnerability scale. This score is due to high sensitivity and exposure to climate change variables, coupled with a variable condition and a moderate adaptive capacity.

Wooded slopes and valleys in the PDNP are already in a poor state, with low diversity and invasive species in many areas, and replacement by conifer plantations affecting others. An increased prevalence in extreme events, rainfall and higher temperatures would have a large negative impact on the woodland significantly affecting the feature. The feature may be damaged directly or indirectly by invasive species, nutrient changes and human behaviour change resulting from climate change.

Slopes and valleys with woodland are somewhat resilient as there are funds available through environmental stewardship options and other national schemes for maintenance, restoration and tree establishment. However significant intervention will be required in order to make this feature resilient to climate change.

Current condition:

In certain areas woodland diversity has been reduced by the isolation of their location, high levels of grazing by deer and sheep, and invasion by rhododendron. Deer and sheep alter the structure of the woodland, reducing woodland regeneration by damaging young trees and impacting plants on the woodland floor.

Diverse semi-natural habitats, such as native woodland, have been replaced in places by less diverse conifer plantations. Some native woodland habitat still exists within moorland cloughs but the condition is often poor and suffers damage from grazing. The location of these clough woodlands contributes to the diversity of the landscape. The dry slopes provide a contrast to the wet moorland tops and streams at the bottom of cloughs, allowing for more plant diversity.

Ash dieback has been found within the PDNP however it is currently much more of a problem in the White Peak where ash dominated woodlands are found. (see ‘Limestone Dales’ for more information).

Historic management of woodlands, including coppicing and pollarding has had an impact on woodland structure, leaving some woods with a lack of veteran trees and deadwood. However, these management features can also have heritage significance in their own right particularly where associated industrial and other sites remain. In other places an absence of management has led to woodland undergoing successional changes that would have previously been prevented.

As well as some mismanagement of the woodland within the valleys, people have also developed these valleys for housing, quarrying and recreational facilities. This can all lead to destruction, disturbance, trampling and pollution of these environments.

Nitrogen deposition from air pollution and nutrient enrichment from agricultural changes on nearby land have both had an impact on the woodland within the slopes and valleys of the PDNP. In particular lichen and bryophyte communities are affected by these changes.

What are the potential impacts of climate change?

Overall potential impact rating

Direct impacts of climate change

Mature and veteran trees could be lost if storm events including strong winds increase. This could then have a knock on effect to specialist species associated with veteran tree habitat such as fungi, invertebrates and lichens. Rowan and birch could become more dominant in areas affected by damage to oak trees, changing the appearance of the landscape. Data Certainty: High

Altered seasonal rainfall patterns could have a significant impact on this feature. Drier and warmer summers and an increase in frequency and severity of drought could impact on drought sensitive tree species especially sycamore within dry woodlands, and particularly those in shallow free-draining soils and clay soils. This is also true of ferns, bryophytes and lichens that prefer a cool wet climate. In extreme drought many trees and plants could be lost entirely. Data Certainty: High

Increasing temperatures can also affect the phenology and health of woodland species; buds can burst earlier and as winters are warmer cold hardening may not happen. This could negatively affect species by risking a mismatch with other species, or by impacting those species that depend on undergoing a cold hardening process as part of their life cycle. Data Certainty: High

In wetter conditions the ground may become waterlogged restricting the root depth for species intolerant of such conditions. Shallower tree roots may increase the risk of wind throw and exacerbate the effects of summer drought while waterlogging can also reduce soil stability. Such changes could see an increase in dominance of wet woodland species, for example alder and willow, and change the composition of native woodlands. The appearance of wooded river valleys could be changed as a result. Data Certainty: High

The growth of trees and productivity may be enhanced by changes in atmospheric composition allowing young trees to grow quickly and increase leaf area. This could see an increase in shading and change the composition of ground flora composition and regeneration capacity. Data Certainty: Low

Invasive or other species interactions

Fewer frost events could see a greater prevalence of diseases and enable species such as deer and grey squirrel to survive in higher numbers, affecting woodland regeneration. Data Certainty: High

Changes in seasonal rainfall patterns could see a rise in pathogens, flooding, increased fluctuation in the water table and the spread of invasive plant species. Changes to wetness can increase the impact of disease and invasive species by making trees stressed and therefore more susceptible. Invasive or nuisance plants, such as Himalayan balsam and rhododendron are a threat to the understorey of woodland. The risk is especially high for woodland located near water courses as invasive species colonise these areas easily. The number of key canopy species in woodland could be impacted which in turn could increase the vulnerability of ground flora to drought, altering the ground flora habitat composition. Data Certainty: High

The complete loss of trees during storms or flooding events could open up bare ground increasing the risk of invasive species colonisation. Rich ground flora such as bluebells and wild garlic could be replaced by invasive species including Himalayan balsam and rhododendron. Data Certainty: Low

Higher average temperatures may lead to an increase in growth rate of riparian invasive species such as Japanese knotweed and Himalayan balsam. This could lead to the destabilisation of slopes and river banks as well as a reduction in the diversity of ground flora. Data Certainty: Low

Human behaviour change

If summers become drier, the economics of farming and forestry may change, as drier woodlands may be more suitable for grazing or forestry. In areas not protected by Site of Special Scientific Interest (SSSI) designation, woodlands may be more sensitive to both of these activities leading to damage to ground flora and the loss of species including birds and invertebrates as well as heritage assets. Such changes could affect historic woodland and reduce the visual appeal of these sites. Data Certainty: High Visitor numbers could increase in hotter drier summers leading to ground flora being trampled and damaged, and wildlife being disturbed. This could also lead to the loss of bird and invertebrate habitat. Data Certainty: High

Conversely, the demand for carbon sinks through the creation or extension of woodlands, such as clough woodlands in the Dark Peak, could increase biodiversity and improve the habitat for birds such as pied flycatchers. Such a move could also improve the resilience of the landscape to erosion and flood risk, both assisting with its preservation. Data Certainty: Low

Increased demand for renewable energy may result in river flow being harnessed for energy generation. The addition or modification of reservoirs and installation of hydropower schemes (including small-scale and microgeneration) would affect the landscape, habitats and aesthetics. Data Certainty: Low

Nutrient changes or environmental contamination

Warmer temperatures may suppress the release and uptake of carbon dioxide in woodlands, as suggested by a Forestry Commission study in the south of England. Woodland could take up less carbon dioxide during the day and also release less during the night, which may have implications for tree growth. Data Certainty: Moderate

Lichen and bryophytes are sensitive to air pollution which could see the loss of some species and a rise in others. This could result in a minor change of appearance of these landscapes. Data Certainty: Moderate

Hotter, drier summers and wetter winters could see more of a change in the community composition and habitat of ground flora, lichen and bryophyte communities. This could be due to further agricultural changes to adjacent land in order to increase productivity, in particular nutrient enrichment. Data Certainty: Low

Sedimentation or erosion

An increase in evapotranspiration in hotter summers could impact ground conditions and the stability of slopes. This may cause the shrinking of clay and shale soils. If the erosion of slopes increases, run off rates may increase and vice versa. This would leading to a rise in flood risk downstream, and could alter the appearance of the landscape. Data Certainty: Low

Wetter winters could also see slopes become less stable if subject to increased hydraulic action. This could damage woodland ground flora. Data Certainty: Low

Other indirect climate change impacts

Drier ground conditions caused by hotter summers could increase the risk of wildfire. Although broadleaved trees such as oak are relatively resistant, there is a risk to ground flora and understorey. Any damage from fire could alter the habitat composition and character of woodland trees and ground flora, also leading to the loss of nesting and feeding habitat. Data Certainty: Moderate

What is the adaptive capacity of slopes and valleys with woodland?

Overall adaptive capacity rating

Generally woodlands on slopes and within valleys within the PDNP are fragmented and small in scale. Oak woods are confined to cloughs and valley sides. Connectivity varies, and is often low, reducing the adaptive capacity of this feature. However, some woodland species can exist within a wide range of elevation, habitat and isolation gradients which means connectivity between different areas should be possible and could be improved. Data Certainty: High

Mixed species woodlands will be more resilient to outbreaks of disease and pests. Woodlands dominated by a single species such as plantations are at risk, but there are significant areas of conifer plantation that could be diversified. This work would be reliant on water companies and the Forestry Commission and could alter the contribution of this feature to its special quality. Data Certainty: High

Environmental stewardship options and other national schemes are available for maintenance and restoration of woodland. Data Certainty: High Organisations such as the Moors for the Future Partnership and National Trust are able to facilitate works to increase resilience of woodland, including clough woodland establishment to increase the cover of woodland within slopes or valleys. Data Certainty: High

Large stands of woodland are more resilient against extreme temperatures due to their cool and humid microclimate. Dry woods may have increased anchorage through the root system which grow deeper to access water or overcome potential nitrogen deficiencies. These deep roots provide stability in high winds and storm events. Woodland tree growth is limited by water availability and exposure to harsh climate, which could affect future woodland regeneration. Data Certainty: Moderate

Woodland can help to make the slopes and valleys more resilient to future climate changes. On slopes woodland can decelerate water flow and reduce flood damage to lower lying landscapes, while riparian woodland has the potential to reduce water temperature in summer through its shading effect. This would help to protect fish and invertebrate populations. Woodland has the capacity to reduce erosion by stabilising soils. Data Certainty: Moderate

Management can be undertaken to partially offset the effects of climate change stressors. Structural and species diversity can be promoted and water availability can be managed. Data Certainty: Moderate

Key adaptation recommendations for slopes and valleys with woodland:

Improve current condition to increase resilience

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations are aimed at improving the condition of the feature at present, therefore making it better able to withstand future changes to climate.

• Reduce grazing pressure where possible, for example reducing deer and sheep numbers to allow for more flowering and seed setting of ground flora, increasing the potential for populations to survive drought years.
• Encourage and protect regeneration where appropriate. Natural regeneration including a scrub phase will benefit biodiversity and ecosystem services. Establish significantly more tree cover in the upland valleys of the Dark and South West Peak, where appropriate.
• Consider blocking artificial drainage channels within woodland in areas predicted to become drier.
• Undertake contingency planning for outbreaks of new tree diseases.
• Develop fire contingency plans, and ensure management of habitats reduces fire risk e.g. rewetting and increasing species or structural diversity.
• Influence visitor and behaviour management plans and practices to minimise ignition risk.
• Include surveys for heritage significance to enable protection of the historic environment to be built into woodland management practices.
• Consider the impact on key views when planning adaptations.

Improve current condition to increase resilience: Increase structural diversity of the landscape to improve resilience to change

The current condition of a feature is an important factor alongside its sensitivity and exposure, in determining its vulnerability to climate change. These recommendations focus on increasing the structural diversity of the area or habitat in which the feature is found. This can help to offset the effects of climate change on the feature, as well as to allow it to be in a better position to recover from future climate changes.

• Continue improving woodland condition through the careful management of plantations and more native plantings. Replace non-native conifer plantations with native broadleaved woodland.
• Encourage a greater mix of native trees through active management.
• Replace unused small plantation woodland with native broadleaf woodland.
• Increase the age structure and structural heterogeneity of woodland, for example by reducing coupe size i.e. the area harvested in one operation and encouraging continuous cover forestry rather than large scale clear felling.
• Take positive steps to increase the proportion and diversity of decaying wood throughout sites to ensure both, resilience of dependant species, and the replenishment of woodland soils’ organic content.
• Allow natural woodland processes and/or woodland management to promote a diversity of age structure within woodlands. This may include retaining some undisturbed old growth stands, encouraging natural regeneration, allowing pockets of wind throw trees and deadwood, and creating a ‘graduated’ woodland edge as opposed to a sharp boundary with neighbouring land uses.

Adaptations that could aid other features

These recommendations are changes that could be made to this feature, which will have a positive impact on the ability of other vulnerable features to withstand future climate change.

• Link woodland patches together - to provide wildlife corridors.
• Increase woodland cover and the shade/shelter for other species as temperatures rise.
• When determining the optimal management of sites, consider the requirements of key species such as woodland birds to ensure minimum patch size is retained.