New Forest climate risks/opportunities assessment

Summary

Climate change is increasingly viewed as the greatest long-term threat to biodiversity and the natural environment, both globally and locally in the New Forest. At a local level, Met Office projections suggest a continuation of trends observed over the last two decades, with hotter drier summers, milder wetter winters, rising sea levels, and more frequent episodes of extreme weather leading to increased risks of drought, flooding, and wildfire. In the last four years alone, the New Forest has experienced record summer temperatures (2022), the wettest winter on record (2023/24), and one of the driest and hottest spring/summer periods on record (2025). These changes are impacting the management and use of the National Park by people, and the associated ecosystem services and benefits that the New Forest provides.

This report, commissioned by the New Forest National Park Authority, assesses climate change risks and opportunities for the New Forest National Park. It forms a contribution to the YouCAN project, which is funded by the National Lottery Community Fund.

The report focuses on the natural environment and the special qualities that distinguish the New Forest from other parts of lowland England, and that underpin the conservation designations and landscape character that provide the unique sense of place that is the New Forest National Park.

The assessment uses land-cover mapping, coupled with an assessment of habitat sensitivity to climate and consideration of adaptive capacity, to produce a series of maps showing the spatial distribution and magnitude of risk across the landscape. Key points from the habitat assessment are:

• More than one-third (37%) of the New Forest National Park is at high or very high risk of habitat loss or damage due to climate change. This includes freshwater and wetland habitats that are highly sensitive to changes in precipitation and temperature, coastal habitats that are unable to naturally migrate in response to sea-level rise, unique ancient pasture woodlands featuring a high proportion of drought sensitive Beech and heathland habitats that are vulnerable to wildfire.
• Measures to mitigate the impacts of climate change on freshwater and wetland habitats are largely the same as those needed to improve ecological status, i.e. more effectively protecting habitats from pollution, restoring natural flow/hydrology wherever possible, retaining or increasing shade and natural features within channels, and creating new ponds and freshwater features to increase resilience and connectivity.
• Sea-level rise is a major socio-ecological challenge for the New Forest, for which anticipation and planning are essential, involving active engagement with statutory processes. Coastal ecosystems, some of which are already highly degraded, deliver a multitude of ecosystem services. Nature-based solutions have the potential to play an important role in maintaining and enhancing these services in the long term.
• Both wet and dry heathlands require active management coupled with restoration to reduce fragmentation and isolation, mitigate wildfire risk, and restore hydrology to maximise resilience to climate change.
• Risks to woodland habitats vary depending on a range of factors including species type and provenance, soil conditions and setting, stand size, and exposure to aggravating pressures. As noted above pasture woodlands have been rated as very high risk due to the relative importance of Beech in New Forest pasture woodlands, their sensitivity to drought and the very low adaptive capacity of these habitats to naturally regenerate under high grazing pressure. Other woodland types (riverine and bog, managed broadleaf and conifer) have been grouped as moderate risk. Some of the commonest tree species are poorly adapted to cope with changing hydro-meteorological regimes and/or the pressure of new and existing pests and diseases. Both natural regeneration and the use of seed and saplings of species with southern provenance are strategies that are expected to increase woodland resilience to climate change. Woodland creation opportunities provide an important pathway to increase connectivity and size of wooded areas which also increases climate resilience.
• Climate change risks to the natural environment are amplified, in nearly all cases, by the presence of other pressures such as fragmentation, pollution and agricultural intensification. Reducing these pressures will increase the resilience of the New Forest landscape and biodiversity to climate change.
• Highly modified grasslands deliver some of the lowest biodiversity and ecosystem service values of the New Forest landscape - there are numerous opportunities to increase the contribution of these grasslands to climate resilience through improving soil health, restoring hydrology and water features, and reducing intensity of use to allow more habitat heterogeneity (hedges, edges, field margins).
• In all cases, improved monitoring will be vital to understand how these habitats are responding locally to climate change, and to inform appropriate iterative management.

The map below shows the spatial distribution of climate risk for New Forest habitats, based on land-cover data and a combined habitat sensitivity and adaptive capacity rating.

The table below summarises the spatial extents of the different risk classes.

Alongside the habitat assessment, which forms the core of this study, a review of climate risks to 1) species, 2) pests and diseases, 3) natural capital and ecosystem services, 4) heritage, 5) landscape, and 6) the special qualities of the New Forest have been completed. For species, the key points are:

• The New Forest is increasingly recognised for its exceptional species diversity, which includes an estimated total of over 20,000 species of animal, plant, and fungus. In the UK, climate change is already the second most important driver of change in terrestrial and freshwater species abundance and distribution, behind (primarily agricultural) land-use change.
• Species responses to climate change can generally be considered as changes in 1) distribution, 2) phenology and behaviour, 3) physiological and/or genetic evolution, and 4) (ecological) network interactions. Distribution and phenology are the most easily observed and widely researched.
• Climate change creates dispersal / expansion opportunities for multiple New Forest species groups, with the potential to improve biodiversity in other regions. Dispersal success depends on many factors including existing population size, dispersal capabilities, availability of habitat and food, and the pathways and barriers (e.g. verges, roads) associated with movement.
• There is likely to be a continuing increase in the number of new species of southern provenance arriving naturally, and increased survival of anthropogenically-assisted invasive non-native species.
• There is potential for loss of species that cannot tolerate the new climatic envelope of the New Forest, including tree and plant species that may lead to changes to the visual landscape. However, variations in microclimate can significantly exceed the projected magnitude of climate change, highlighting the importance of habitat heterogeneity and potential for habitat refugia to provide a buffer to climate change at very local levels, offering opportunities for species to persist beyond macroclimatic thresholds.
• The impact of range shifts on ecological networks is poorly understood but has the potential to impact ecosystem function and associated ecosystem services.

Key points from the remaining sections are:

• Pest, pathogen, and disease risks to people, animals, and plants are all increasing in response to climate change and will continue to increase in the future. This includes vector-borne diseases transmitted by ticks and mosquitos, fungal pathogens, and mobile insect pests. Increased monitoring and awareness are vital to inform early intervention.
• Biodiversity underpins the ecological condition and quality of ecosystems that together form the natural capital of the New Forest, that directly benefits people through delivery of a diverse range of ecosystem services. There is a high risk that these services will be modified by climate change, but also a wide range of opportunities to enhance natural capital whilst also increasing climate resilience and delivering adaptation. Mobilising public and private finance to support natural capital investment is an increasingly important opportunity for the New Forest.
• Climate change increases the risk of damage and destruction of heritage assets through mechanisms such as coastal erosion, water damage, subsidence, vegetation growth, fungal decay, and extreme event impacts. These will increasingly force a reconsideration of how some heritage assets are managed and maintained; in some situations, full or partial loss or extensive adaptation will be necessary. This may increase the potential for conflict within the planning system as sympathetic adaptation may not always be viable.
• Beyond risks to physical heritage assets, climate change has potential positive and negative impacts on cultural heritage including the local commoning community. Although climate change will likely increase costs of livestock management, the landscape-scale conservation grazing provided by commoner’s livestock will be increasingly recognised as an essential tool for climate resilience, including vegetation management to reduce wildfire risk.

The New Forest is special because much of the landscape has been protected from the land-use intensification of past decades. Going forwards, a combination of legal protection, active commoning, and conservation-informed forestry will help to sustain a high-quality and diverse mosaic of habitats. However, current evidence is unclear as to whether overall New Forest biodiversity and ecosystem services will increase, as is likely to be the case in the short term, or decline, which remains a significant risk in the longer term. Much will depend on how effectively the collective interests of New Forest landowners, residents, and visitors can be aligned to address the needs of habitats and species, and how willing people are to support and implement change.

As well as risks, climate change also creates opportunities. The New Forest is one of the most biodiverse landscapes in the UK, loved by many, with a rich cultural heritage, strong local communities, and a historic and thriving practice of biological observing and recording. Climate change provides a shared challenge and opportunity to leverage the strengths of the New Forest to rebuild human connection with the natural environment, to understand and learn from change, to innovate, to show national leadership and to learn from and share solutions, approaches, successes and failures to support the collective challenge of increasing resilience and adapting to climate change.

The study outlines 13 opportunities that are grouped into six themes: Lead, Learn, Enable, Protect, Manage, Restore & Create. These opportunities are summarised as O1-13 in the table below.

Lead

Learn

Enable

Protect

Manage

Restore & Create

Table of Contents

Acknowledgements

This work has been delivered by a small team under the oversight and guidance of John Stride at the New Forest National Park Authority. Christine Sams (Wild New Forest) led the writing and literature review, Andy Murdock (Maploom) led the mapping and spatial analysis, and Prof Russell Wynn (Wild New Forest) provided input throughout, particularly on local ecology.

Our sincere thanks go to all those who have discussed this work and provided input including Steve Cham (independent odonatologist and author), Clive Chatters (independent naturalist and author), Paul Edgar (Amphibian and Reptile Conservation Trust), Dom Longley (Environment Agency), Andrew Parry-Norton (Chair, Commoners Defence Association), Mike Pittock (Forestry England), Daisy Slocombe (Chair, New Forest Young Commoners), staff at the National Park Authority and New Forest District Council, and workshop attendees at the 2025 New Forest Biodiversity Conference.

1 Introduction

This report provides a baseline assessment of the climate change risks and opportunities facing the New Forest National Park. The work was commissioned by the New Forest National Park Authority (NPA) as part of the YouCAN project, funded by the National Lottery Community Fund.

The New Forest National Park (referred to in this report as the New Forest) is an extraordinary place for nature. This is primarily because it has survived, for the most part, the dramatic changes in land use seen across the UK since WW2. The diverse landscape of the New Forest supports nationally and internationally important assemblages of wildlife and provides ecosystem services to millions of people. This includes around 35,000 residents living within the National Park, almost 1 million residents ‘on the doorstep’ and c. 3 million annual day visits by tourists and holiday makers from further afield¹.

The primary aim of this work is to improve understanding of how the changing local climate will impact the New Forest and identify opportunities that arise in response to climate change. The focus is firmly on the natural environment, as it is primarily this characteristic which distinguishes the New Forest from other areas of lowland England and underpins its various conservation designations and the landscape character that provides the unique sense of place that is the New Forest.

As guardians of a national park, the New Forest National Park Authority (NPA) has statutory purposes and socio-economic responsibilities as specified in the Environment Act of 1995:

• To conserve and enhance the natural beauty, wildlife and cultural heritage of the area
• To promote opportunities for the understanding and enjoyment of the special qualities of the National Park by the public.

Working in partnership with other organisations it is also the Authority’s duty to seek to foster the economic and social well-being of the local communities within the National Park.

The NPA sum this up as: Protect – Enjoy – Prosper

As of December 2023, under the new Protected Landscapes Duty, Government departments, public bodies, statutory undertakers (such as utility companies) and persons holding public office must now ‘seek to further’ these statutory purposes.²

A second aim of this study is to inform the development of the next iteration of the New Forest National Park Partnership Plan (due in 2027).

This section, Section 1, sets out the methodology used in this study and the climate change context. Section 2 assesses the risks of climate change considering the New Forest purposes. Section 3 identifies climate change opportunities for the New Forest.

¹ Based on the Liley et al. 2019, visitor survey data, using total estimated day visits per annum of ~15 million

² See UK Government guidance and Campaign for National Parks (CNP) explainer

1.1 Approach

The study has been guided by the approach defined in ISO 14091:2021³ using the conceptual framework for risk illustrated in Figure 1. Definitions for the terms used are provided below.

Risk is used to describe the potential for adverse consequences.

Climate Hazard refers to projected changes to the climate in response to greenhouse gas emissions; the data used for this assessment are discussed in section 1.2.

Exposure refers to the presence of an asset, habitat, or species in a location that could be adversely affected, i.e. reflecting how many and/or how much is potentially impacted by the risk. This is assumed to be uniform across the New Forest. In reality there are significant differences in climate depending on the scale considered (i.e. cm to km), including the marine/coastal influence and topographic variation. The future climate projections used in this study are km scale and therefore these variations have been assumed to be negligible. Alongside spatial variability, exposure also has temporal variability. This is illustrated clearly in the work of Wilson and Pescott (2023), Figure 2, which shows the increasing effect of climate change over time and variation in exposure across the UK. The New Forest is within the region with the greatest exposure.

Response acknowledges that the natural environment of the New Forest is a managed landscape and that the type of management in place now, and potential changes to management in the future, have an impact on and can mitigate climate risk.

Vulnerability is an assessment of the sensitivity of a particular asset, habitat, or species to climate change and its adaptive capacity, where Sensitivity is used to mean the degree to which a system is affected, positively or negatively, by climate change and Adaptive Capacity is used to describe the ability of a system to adjust to potential damage; this might be to limit that damage, take advantage of opportunities, or otherwise cope with the consequences of climate change. Adaptive capacity is used here to reflect either inherent properties or associated human actions carried out in response to, or in anticipation of, changes in climate.

Resilience is another term used throughout this report. It is defined as the ability of a system to absorb disturbances while retaining the same basic functions; a resilient system has capacity to adapt to stress and change.

Opportunity refers to potential actions that could be taken to reduce risk.

³ Adaptation to climate change — Guidelines on vulnerability, impacts and risk assessment

Figure 1: Conceptual Framework for Risk based on the approach used in IPCC AR5.

Figure 2: Spatial differences in climate change exposure across the UK (left), UK landcover map (right) (Wilson and Pescott, 2023).

1.1.1 Scope

The risk assessment covers habitats and those characteristics of the New Forest National Park that are particularly connected to habitats i.e. heritage, landscape, the special qualities of the National Park, pest and disease risks, and risks to natural capital and ecosystem services. A section on species risks has been included, although within the scope of this study the detail is limited. There is much more work that needs to be done to understand how species assemblages and their interactions are being influenced by climate change, and how they might continue to change in the future.

The work has been drawn together using academic and other literature, supplemented by local knowledge and experience where possible. The consultation process has been non-exhaustive. Drawing on wider perspectives and experience from those who live, work, and visit the New Forest is an essential ongoing task in the process of mitigating climate risk and adapting to climate change.

The risk assessment approach varies by topic. Habitats form the core of the risk assessment and the most substantive section of the report. The main aim has been to establish how vulnerable the New Forest habitats are to climate change and where the greatest vulnerabilities are (spatially). Habitats have been given a risk rating based on a combination of their sensitivity to climate change and adaptive capacity, with the results geospatially mapped. For the remaining topics the sections provide summary information of current understanding of climate risks and impacts from a New Forest perspective. Apart from pest and disease risks these have not been assigned risk ratings.

All the assessments have been made considering a medium emissions scenario (RCP 4.5⁴), the projected consequences of which are described in Section 1.2. Under a lower emissions scenario the impacts are likely to be reduced, whereas higher emissions will lead to more rapid and extreme changes to the climate making it harder for the natural environment to adapt. No attempt has been made to map impacts to different emissions scenarios or time steps at this stage. For the scopes assessed, in all cases risks increase as emissions increase, and in all cases both risk and uncertainty increase over time.

Figure 3: Natural England’s Landscape Scale Climate Change Assessment Methodology Flow Chart showing the steps completed in this assessment.

⁴ RCP’s (Representative Concentration Pathways) are sets of assumptions about the economic, social, and physical changes to our environment that will influence climate change. Each RCP pathway represents a plausible future that results in a different level of global warming relative to the pre-industrial era (taken as 1850 – 1900).

Geospatial data and mapping

A variety of geospatial data have been used to inform the risk assessment. Spatial extents of priority assets (habitats, agriculture, and historical sites) have been defined using readily available GIS datasets. Where possible, a single dataset was used to maximise consistency.

By mapping asset extent, it is possible to see where the current stock of assets is located throughout the New Forest National Park, and by understanding the vulnerability of these assets to climate change impacts, where the areas at risk are and where action needs to be taken.

The datasets used are:

• Priority Habitat Inventory (Natural England)
• Ancient Woodland Extent (Natural England)
• National Forest Inventory (Forest Research)
• Heritage assets (Historic England)

Several features of interest were either not available as GIS datasets or were only available as a low-resolution layer, missing detail and smaller features. To address this, some features of interest have been extracted from the Ordnance Survey’s highest resolution data via the OS Maps API under the NPA PSGA licence. These features include:

• Springs, water courses, drains, conduits and standing water, ponds
• Agricultural land and glasshouses

Further processing has been implemented to enhance the OS features with data from the Priority Habitat Inventory layer, which enabled the separation of arable land from pasture.

Several other sources have been used to provide additional information and context, such as:

• Soils (British Geological Survey)
• Peaty soils (Natural England)
• Terrain and tree canopy (Environment Agency)
• Legal and administration boundaries (Forestry Commission, NPA)

Flood risk was identified using:

• Flood Zones (Environment Agency) – climate change flood risk layer.

It was not possible to define spatial extents from existing GIS data for:

• Peat Bogs and Valley Mires
• Riverine and Bog Woodland

All datasets have been cropped to an extent based on the New Forest National Park boundary with a 1km buffer zone applied. This allowed for the visualisation of connectivity of the selected assets outside the National Park and calculations both inside the National Park and within the buffer zone.

Data have also been segmented based on other extents of interest (e.g. open forest, Crown Lands etc) for additional calculation of area statistics.

Mapping and geospatial analysis was undertaken in Maploom® and provided as an interactive platform for the project: https://nf-ccra.maploom.com

1.2 Past, Present, and Future Climate

The term climate is used to mean average weather, typically looked at over a period of 30 years. There is now unequivocal evidence that climate change is increasing average temperatures, driving sea level rise, and making extreme weather such as heatwaves and heavy rainfall more likely in the UK. In 2024, annual global average temperatures exceeded 1.5°C above pre-industrial levels for the first time.⁵

Global greenhouse gas emissions continue to increase⁶, on a trajectory that suggests global average warming will reach 2°C in the next 25 years, with the possibility of significant further warming by the end of the century (see footnote 5). The implications are that the New Forest will face more unpredictable conditions, with higher year-round temperatures, more frequent extreme heat and drought conditions, and more intense rainfall leading to increased flood risks. The risks of exceeding ‘safe limits’ are growing.

In July 2022, Met Office records show that southeast England reached a record temperature of 40.2°C, resulting in ~3000 heat-related deaths and an unprecedented number of wildfires. The preceding winter and subsequent summer of 2022 received significantly less than the usual levels of rainfall, leading to extensive drought. Attribution studies show that these extremely hot and dry conditions were made 10 times more likely as a result of climate change.⁷ In the New Forest, sections of the Highland Water dried up for the first time in living memory.

Beginning almost immediately after this hot dry period, England experienced the wettest 18 months on record. The plots in Figure 4 show how different the temperatures and precipitation rates were during the summer of 2022 and winter of 2024 compared to the average. The images in Figure 5 illustrate some of the impacts of these conditions in the New Forest.

Figure 4: Met Office plots showing the hot dry summer of 2022 (left) and warm wet winter of 2023/2024 (right)⁸.

Figure 5: Images, left to right, Beech leaf fall in the August 2022 drought (Busketts Wood), fallen tree on a New Forest Road (Bolderwood), grazing lawn inundated during flood (Longwater Lawn).

The UK Met Office, UK Climate Change Committee and Intergovernmental Panel on Climate Change (IPCC) AR6 Synthesis report provide detailed authoritative information on climate change.

The next section provides a short overview of past and future projected climate of the New Forest extracted from the Met Office UKCP18 User Interface, Climate Data Portal and the Local Authority Climate Service. A more detailed assessment is provided in Report 1: New Forest Climate (Jan 2025).

Table 1 (below) shows average annual and seasonal temperatures and rainfall in the New Forest over the past 40 years, alongside projected changes to these averages in the future covering four different time intervals through to 2100¹.

The future projections are probabilistic (i.e. behind these data are a full a range of potential outcomes with an associated probability of occurrence). Representative Concentration Pathways (RCP’s) provide projected temperature changes under different emission scenarios; there are three commonly used scenarios:

• RCP 2.6 represents a future with strong global action on climate change resulting in a median global temperature increase of c.1.6°C by 2081.
• RCP 4.5 is a medium emissions scenario that results in a best estimate median temperature change of 2.4°C by 2081.
• RCP 8.5 is a high emissions scenario that results in a best estimate median temperature change of 4.3°C by 2081.

The values shown in black are the median (central) result for the intermediate emissions pathway (RCP4.5). The values in grey are the median results for a low (RCP2.5) and high emission scenario (RCP 8.5).

For context, the WMO report that the 2024 global average temperature was about 1.55°C above pre-industrial levels, and the past ten years (2015 – 2024) are the ten warmest years on record.

Table 1: Past and future climate projections for the New Forest National Park (based on 25km resolution data). The grey numbers shown are the median (central) results for a low (RCP2.5) and high emission scenario (RCP 8.5). Future projections are relative to the average of the period 1981 to 2000.

Table 1 clearly shows the headline trends: higher average temperatures for all seasons, drier springs and summers, and wetter autumns and winters. Importantly, overall precipitation is not expected to vary significantly.

It is important to interpret these data within the context of UK weather patterns. UK rainfall patterns are not uniform and vary on seasonal and regional scales; these will continue to vary in the future. Natural variation means that some cold winters, some dry winters, some cool summers, and some wet summers will still occur. Analysis by the Met Office shows that while the projections show a clear shift to higher probabilities of drier summers, they also suggest that the likelihood of individual wet summers reduces only slightly (Maisey, 2019).

For other climate variables, the UK Climate Projections (UKCP18) suggest the following for the New Forest region:

• Negligible change to windspeeds (within +/- 0.5m/s to 2080’s)
• An increase in the magnitude, frequency, and duration of heatwaves and drought conditions
• An increase in the intensity of rainfall (~25% increase in summer and autumn)

The implications of hotter, drier summers are an increase in the magnitude and duration of wildfire conditions, especially in central and eastern southern England (including the New Forest).

Alongside temperature, the other clearest signal of climate change is sea-level rise, and an ongoing increase to mean sea level at the coast. The projected increases in sea level for the New Forest coast are shown in Table 2.

Table 2: Change in sea level with reference to 1981 – 2000 baseline (cm) (spatial average calculated as the mean of all grid boxes along the coastal boundary of the NFDC Local Authority area). The upper value shows the central projection; the range is provided in grey italics underneath.

Both increases in average temperatures and changing concentrations of CO2 in the atmosphere have implications for plant growth. Growing degree days are a metric of the number of days above a threshold temperature (5.5°C) used to indicate when conditions promote growth in the natural environment. Table 3 shows how the growing degree day indicator increases with different thresholds of warming, alongside frost days and very hot days (>25°C). The implications for plants of increasing CO2 concentrations have not been discussed in any detail in this report.

Table 3: Projected changes in annual growing degree days, frost days, and number of days exceeding 25°C for the New Forest region.

⁹ Growing Degree Days indicate if conditions are suitable for plant growth. A Growing Degree Day (GDD) is a day in which the average temperature is above 5.5°C. It is the number of degrees above this threshold that counts as a Growing Degree Day. E.g. if the average temperature for a specific day is 6°C, this would contribute 0.5 Growing Degree Days to the annual sum, an average temperature of 10.5°C would contribute 5 Growing Degree Days.

The impact of shifting averages on extreme events

Alongside changes to average conditions, analysis of UKCP18 data show an increase in the frequency and intensity of extremes. An extreme weather event is one that is rare at a particular place and time of year, with unusual characteristics in terms of magnitude, location, timing, or extent.¹⁰ These events are above or below a threshold near the upper or lower (tail) ends of the range of observed values in a specific region. Even if a weather or climate event is not statistically extreme, there are cases where an event, an accumulative series of events, or a specific combination of events can lead to extreme conditions or impacts (e.g. a simultaneous high tide, storm surge, and heavy or prolonged precipitation leading to extensive flooding).

It is predicted that as the climate continues to change the New Forest will be subject to climate hazards and extremes of different frequency, severity, and duration. UKCP18 results highlight that from the 2050s onwards, higher emissions scenarios are projected to lead to greater increases in extreme weather and sea level and that the severity of extremes is projected to increase with global warming. It is also important to note, however, that unprecedented extremes will continue to occur in the future as a result of natural variability.

There is an increasing risk of passing climate ‘tipping points’ as global warming progresses. Tipping points are thresholds in the earth system that, if crossed, lead to large, accelerating, and potentially irreversible changes to our current climate - examples include changes to ocean circulation or loss of major Antarctic ice sheets. The impacts of crossing these tipping points are not included in the climate projections and remain poorly understood. As a consequence, there is a residual risk of rapid changes in climate outside the envelope of scenarios currently modelled by the UKCP18 suite of climate projections.

¹⁰ https://wmo.int/topics/extreme-weather

2 Climate Change Risks

2.1 Habitats

The New Forest consists of an inter-connected mosaic of habitats including extensive heaths and grasslands (wet and dry), valley mires and bogs, ancient pasture woodlands, and forestry inclosures. The interior contains a network of rivers, streams, and ponds, while the 26 miles of coastline feature shingle beaches, saltmarshes, lagoons, and mudflats.

Residential and commercial developments within the New Forest range from single dwellings and small urban centres to large private estates which include land managed for farming, shooting, and fishing. Interactive versions of maps in this report are available here: https://nf-ccra.maploom.com/

Figure 6: Habitat map of the New Forest showing the National Park boundary (solid black line) with a 1km buffer (dotted black line).

2.1.1 Methodology

For the purposes of this assessment, New Forest habitats have been grouped as listed below. In practice, each habitat represents a spectrum of different features or vegetation communities that are dynamic and transitional and encompass within them significant spatial variation.

• Freshwater
• Peat Bogs and Valley Mires
• Coastal and Estuarine
• Heathland
• Acid Grassland
• Woodland, split into old growth pasture, riverine and bog, and other types of woodland
• Agriculture, Horticulture and Modified Grassland
• Soils

Table 4 and Table 5 below show the criteria used to rate sensitivity and adaptive capacity of habitats. Combined (multiplied) these results give overall risk of habitat modification in response to climate change, as shown in Table 6. The assessment is subjective, reflecting published evidence and local experience; these should be modified if new information or understanding becomes available.

Each habitat section includes an overall risk rating and map, a brief summary outlining the rationale for the ratings given, context, more detailed discussion of potential climate impacts, and a short summary of adaptation and mitigation response options identified in the literature. These are expanded and discussed in the context of the New Forest in Section 3 (Opportunities).

A higher level of detail is provided for those habitats that are deemed to be at high or very high risk.

The review has drawn extensively from the key references shown below. Additional sources are individually referenced.

• UK 3rd Climate Change Assessment (CCRA3) and supporting technical reports (2021). Note CCRA4 is currently underway, due for publication in 2026.
• Natural England and RSPB, 2019. Climate Change Adaptation Manual - Evidence to support nature conservation in a changing climate, 2nd Edition. Natural England, York, UK, and the 2023 update (see Staddon, 2023).
• Living with Environmental Change (LWIC): archive of publications and reports.

2.1.2 Summary of habitat results

provides a summary of the risk assessment results for each habitat class. This is followed by three maps which present the results (excluding the soils class) in a visual format, with tables summarising spatial extents for each result.

Figure 7: Map showing results of the climate sensitivity assessment for the New Forest based on habitat classes.

Figure 7 above shows the spatial distribution of the climate sensitivity assessment based on land cover data and the results shown in Table 7.

Freshwater, coastal and estuarine habitats are the most sensitive (very high), driven by the combined effects of rising temperature, lower spring and summer precipitation, and higher drought risks. Coastal habitats are impacted by sea level rise and coastal squeeze.

Wetland bogs, mires, heathland and old growth pasture woodland habitats have been rated high due to their dependence on precipitation and sensitivity to sustained periods of higher temperatures. Old growth pasture woodlands are extremely scarce habitats that are unique to the New Forest. They feature Beech as a major component, are highly fragmented and are under high grazing pressure which prevents natural regeneration.

Riverine and bog woodland alongside other woodland habitat types have been rated as moderate sensitivity, reflecting an understanding that woodlands will certainly survive in this region (notwithstanding a catastrophic disease outbreak), albeit with some changes in species. This rating masks considerable variation in sensitivity between different tree species - some such as Beech are highly sensitive (see e.g. Martinez del Castillo et al., 2022) whereas others, such as Pedunculate Oak are more resilient. There are also variations in sensitivity depending on the type of woodland, with riverine woodland potentially more resilient and woodland on free-draining and more exposed sandier soils potentially less so (depending on which species are located in those areas). Agriculture, horticulture, and modified grasslands have been rated as moderate as these are all highly modified by management, yet also sensitive to temperature and water availability.

Acid grasslands have been rated as least sensitive to the projected changes in climate for this region.

Soils are not shown on the map but have been rated as high sensitivity. Temperature and precipitation are key drivers of multiple soil processes influencing soil health. Physical impacts include increased risk of soil erosion from higher temperatures and repeated cycles of drought and flooding. Drier soils lose structural and water retention capacities. Higher intensity and increased winter precipitation increases the loss of soil nutrients and risk of run-off and erosion of soil into watercourses. Wetter winters increase the duration during which soils are saturated increasing susceptibility to compaction.

Sensitivity of any habitat to climate change may be amplified or moderated depending on the capacity of a habitat (whether naturally or in response to changes in management) to adapt. Figure 8 (below) shows the spatial distribution of the adaptive capacity assessment based on land-cover data and the results shown in Table 7.

Figure 8: Map showing results of the adaptive capacity assessment for the New Forest based on habitat classes.

Two habitats have been rated as having very low adaptive capacity; these are freshwater habitats and old growth pasture woodland. Freshwater habitats have an extremely limited ability to adapt to changes in water volume and precipitation, which can exceed behavioural or survival thresholds of some species. Although flow rates and temperatures vary under ‘normal’ conditions, the magnitude of temperature and volume changes that are anticipated in the New Forest region have the potential to exceed the thresholds of multiple species. Old growth pasture woodlands have been rated as very low due to their fragmentation, very low regeneration success, lifespan and high levels of protection limiting intervention options.

Peat bogs, mires, heathlands, coastal habitats, and all other woodland types have been rated as having low adaptive capacity. This reflects the time taken for these habitats to regenerate (especially some tree species), and their ability to maintain their current composition under a modified climatic regime (including higher sea levels).

Soils and acid grassland have been classed as moderate for adaptive capacity based on an understanding that they are more resilient to climate change than the more water-sensitive types. Confidence in the assessment for soil is low due to a lack of published evidence.

Agriculture, horticulture, and modified grasslands have been rated as having the highest adaptive capacity as they are strongly influenced by human management and can be modified more easily than the more highly protected areas.

The spatial extents of the risk classes within the National Park boundary are shown in Table 10 below. Figure 9 shows the spatial distribution of climate risk for New Forest habitats based on land cover datasets and a combined sensitivity / adaptability rating.

Figure 9: Map showing the spatial distribution of climate risk for New Forest habitats, based on land-cover data and a combined sensitivity / adaptability rating.

2.1.3 Freshwater Habitats

The New Forest contains over 1000 ponds and an abundance of streams that feed into several rivers, which drain into the Solent, the River Avon, and the River Test; the quality and quantity of these freshwater habitats makes the New Forest one of the best Important Freshwater Areas in the UK.

Figure 10: Map showing freshwater habitats and catchments. Sources: Ordnance Survey MasterMap (Standing Water and Water courses), Environment Agency Catchments.

Summary

• The volume and temperature of water available within freshwater habitats is of fundamental importance to their function and condition.
• Within the New Forest, freshwater habitats are primarily dependent on rainfall and surface run-off for their supply, making these habitats very sensitive to projected changes in climate (higher average and extreme temperatures coinciding with lower spring and summer rainfall).
• Across the New Forest, these habitats have exceptional biodiversity. Most aquatic species are ectothermic and highly sensitive to temperature. Those without aerial life stages have limited abilities to disperse in search of cooler conditions.
• Ongoing nutrient enrichment and chemical contamination issues increase the vulnerability of these habitats to climate change.
• Due to the limited ability of freshwater systems to respond to extensive drought, as well as physiological sensitivity of fish and aquatic invertebrates to changes in water temperature, the adaptive capacity of these habitats is very low.

Sensitivity to Climate Change: Very High
Adaptive Capacity: Very Low
Risk Rating: Very High
Confidence: High

Relevant sections of the Natural England & RSPB Climate Adaptation Manual are rivers and streams (sensitivity rated high) and standing open water (sensitivity rated high).

Context

Although the New Forest has a high number of good-quality waterbodies, their status and extent within England is highly degraded. An estimated 90% of wetlands, including 75% of ponds (90% of ponds in lowland England) have been lost over the last century. Most rivers and lakes are not close to their natural state in any part of the UK (Absalom and Bennett, 2024).

Within the New Forest, well over half the total length of main streams and tributaries have been modified in the past by drainage schemes to improve areas for forestry or grazing, dating back to 1870 (Smith, 2006, Part 2). Despite this, the freshwater and wetland habitats of the New Forest are of international importance and are recognised as a Ramsar site and a key feature of the New Forest SAC.

Freshwater and wetland habitats are described in Smith (2006, Part 2) and in the New Forest SAC Management Plan (NE, 2025). Whatley & Ewald (2012) also provide useful context with a focus on freshwater environments. Thomas et al. (2016) describe some of the historical issues of drainage and other physical modifications, and subsequent restoration efforts. The 2019 wetland restoration strategy (Hill et al., 2019) remains current.

There are two catchment partnership groups within the New Forest, the Hampshire Avon Catchment Partnership and the New Forest Catchment Partnership, which is co-hosted by the Freshwater Habitats Trust (FHT) and the NPA. Through the Higher-Level Stewardship Scheme (HLS), and other precursor initiatives, a major programme of wetland restoration in the New Forest has been ongoing since 2010.

Eco-hydrological processes

An understanding of the eco-hydrological processes that support New Forest freshwater and wetland habitats is fundamental to assessing their sensitivity to climate change, and to predicting how they may evolve in the future. A brief overview is provided here for context.

The geology and soils across much of the New Forest are relatively impermeable and consist of a combination of clay, silt, sand, and gravel deposits; these provide limited groundwater to support streams and wetlands, which are mostly dependent on rainfall and surface run-off for their supply. As a result, river flows tend to closely reflect the intensity and duration of rainfall, rising swiftly in response to precipitation. Wetland bogs and mires act as sponges, absorbing and slowly releasing water that feeds the streams that flow into the New Forest and Avon Valley rivers and out into the Solent.

During prolonged dry summers, many of the ephemeral ponds and wetlands, smaller streams, and headwaters exhibit low flows or dry up completely. Natural seasonal drying helps to support important plant and invertebrate communities; however, sudden or unexpected drying of more permanent features has the potential to cause damage to species which have not evolved to tolerate these conditions (Whatley & Ewald, 2012).

Debris dams are important features along the New Forest streams, particularly in wooded catchments where large woody debris influences channel morphology, creating diverse microhabitats and refugia. Woody debris traps sediment and gravel and promotes overbank flow in localised areas, which support floodplain habitats, it also slows downstream flow, particularly during peak discharges, provides food for invertebrates, shelter for fish, and has an overall positive effect on river biodiversity and food webs (Smith, 2006; Thompson, 2017).

In terms of nutrients, the streams of the New Forest are typically base poor with low nutrient concentrations. Water chemistry varies according to the underlying geology, soils, and land use, with waters tending to be particularly acidic in the upper reaches of catchments. The naturally low nutrient levels increase the sensitivity of associated freshwater species to additional organic inputs such as sewage or diffuse pollution from other sources (Smith, 2006).

Periods of low flow can exacerbate water quality issues by reducing the volume of water available for dilution of pollutants, and habitat availability for freshwater species. This tends to occur in the summer when visitor numbers increase, which can exacerbate issues such as pollution and recreational disturbance (Whatley & Ewald, 2012).

Water quantity and quality

The proportion of New Forest waterbodies (rivers) meeting at least good ecological status declined from 20.8% in 2016 to 16% in 2019 (the last full assessment), with none meeting high ecological status (CNP, 2024). Current management issues for New Forest river catchments are:

• Poor water quality, particularly diffuse sources of phosphorus, nitrate, and sediment
• Water quantity, i.e. low summer flows and winter flood conditions
• Habitat degradation, including over-widening of the river channel, disconnection with the floodplain, and physical (man-made) in-channel obstructions
• Morphology, i.e. loss of natural processes, and floodplain and habitat connectivity

Sewage and other chemical pollutants are a major issue, with regular inputs from combined sewer overflows (CSO’s) associated with moderate to high intensity rainfall. This is especially problematic at the head of the Beaulieu River, but also regularly impacts the Lymington River (James and Longley, 2023).

Concerns are increasing over other sources of chemical pollution, including the impact of flea treatment insecticides on freshwater biodiversity, introduced through the increasing number of pet dogs visiting the New Forest and ‘dog dipping’ into water bodies.¹¹ (Perkins et al., 2024).

There are no surface water reservoirs within the New Forest and no abstraction for public water supply from the rivers or groundwater. There are, however, active abstraction licences to support activities including agriculture, horticulture, and the visitor economy (Smith, 2016, EA, 2019c, Southern Water, 2022).

¹¹ See also FHT and BBC reporting.

Species

The freshwater biotic (living) environment includes an incredibly diverse range of fish, amphibians, reptiles, birds, mammals, micro and macro-invertebrates, bryophytes, plants, fungi, algae, and bacteria that all contribute to the ecosystem processes and dynamics of these habitats.

The varied nature and high quality of New Forest freshwater and wetland habitats is reflected in the number of species they support and their importance for nature conservation. These include 30% of England’s threatened freshwater species, 30% of the UKs freshwater invertebrate species (approx. 400 species) and 65% of the UK’s wetland plants (300 species) (Whatley & Ewald, 2012).

Freshwater habitats are also important for vertebrates, with Otter Lutra lutra, Daubenton’s Bat Myotis daubentonii, and Kingfisher Alcedo atthis being relevant examples within the New Forest.

Impacts of Climate Change

Climate change impacts on freshwater habitats can be considered in terms of three types of impact (expanded below):

• Direct impacts in response to gradual changes in baseline conditions (temperature, precipitation)
• Direct impacts in response to episodic ‘pulse’ events (extreme precipitation, flooding, drought, heatwaves)
• Indirect effects (e.g. modified behaviour of people, livestock and wildlife in response to weather)

Direct impacts in response to gradual changes in baseline conditions

Flow and water temperature are the primary variables that influence river ecosystem structure and function. (EA, 2025). Temperature of freshwater bodies is largely controlled by solar radiation and therefore varies diurnally and seasonally in line with air temperature. Temperature is also dependent on water volume and catchment hydrology (i.e. where is the water coming from and how quickly) and other factors such as the geometry and condition of river channels and shading by riparian (bankside) vegetation.

Impacts of warming on fish species are described in Section 2.2.5 and on aquatic invertebrates in Section 2.2.6. A key concern is exceedance of thermal thresholds that may drive population or community change even at sub-lethal levels.

Warming water aggravates pervasive issues such as eutrophication, pollution, and the spread of disease, exacerbating the impacts of low flow rates which concentrate nutrients and pollutants by reducing the volume of water available for dilution.

Phosphorus (P) and nitrogen (N), when combined with higher temperatures, can drive excessive growth of algae and plants and lead to eutrophication¹². This adversely affects water quality and is damaging to local ecology, especially species suited to low nutrient environments (EA, 2022).

Elevated temperature is also known to alter the toxicity of other pollutants such as ammonia, pesticides, and other chemicals. There is evidence that elevated water temperature can alter the bioavailability, toxicity, and bioaccumulation of toxic metals. The impact of how pollutants may affect the ability of an organism to cope with rising temperatures (i.e., toxicant-induced climate sensitivity) is less known. Local monitoring suggests that a combination of contamination and nutrient enrichment, alongside higher temperatures and low summer flows, have accelerated the decline of sensitive fish species, especially in the Beaulieu River (James & Longley, 2023).

Warmer average conditions may increase the suitability of freshwater habitats to non-native species, with the potential to become invasive. They may also alter the balance of competition enabling existing species to become invasive or otherwise dominant with the potential for cascading ecosystem effects.

¹² Phosphorus is the main cause of eutrophication in freshwaters, whereas nitrogen is usually the key nutrient involved in eutrophication in saline waters (EA, 2025)

Direct impacts in response to episodic ‘pulse’ events

Impacts associated with extreme changes in water flow and temperature have been found to substantially reduce species richness in streams and rivers. Of these, flow interruption (i.e. in response to drought) has been found to have the largest impact on river biota and ecosystem function (Sabater, 2022) with the potential to induce regime shifts in river ecosystems, particularly affecting organisms such as invertebrates.

Prolonged low flows and associated temporary reductions in habitat extent and quality lead to increased competition and predation, affect the passage of migratory fish, can increase siltation (due to reduced flushing), increase pollution concentrations, and lead to reduced dissolved oxygen levels in both sediments and overlying water. Vegetation can encroach into channels, further impeding flow and reducing habitat availability.

The species likely to suffer the most are those that are adapted to cool, fast-flowing waters and those that have poor powers of re-colonisation, such as those without aerial or drought-resistant life stages. Ephemeroptera (Mayflies), Plecoptera (Stoneflies) and Trichoptera (Caddisflies) are identified as the most affected groups of invertebrates, as they tend to adapt poorly to warmer temperatures, lower dissolved oxygen levels, and shrinking waters (Sabater, 2022).

As well as droughts, flood risks are also projected to increase. Floods can help to shape and restore modified waterways, but they can also lead to human interventions and modifications to increase protection of people and property from flood risk, with the potential for habitat damage.

High intensity rainfall increases the volume and energy of catchment run-off, potentially generating enhanced loads of fine sediment and diffuse pollutants, particularly nutrients. Siltation and nutrient enrichment are key impacts on freshwater biota. Siltation can lead to smothering of coarse substrates and generate excessive growth of benthic and planktonic algae, leading to declines in species dependent on clean, coarse sediments (e.g. salmonids and many benthic invertebrate species) and species adapted to low nutrient and well oxygenated conditions (e.g. many stonefly species).

Increased scour may partly offset increased pollutant loads by transporting pollutants downstream more effectively.

High intensity rainfall can also cause downstream ‘wash out’ of species, although there is not yet any evidence of this causing issues in the New Forest.

Indirect effects

Consultees have provided anecdotal observations of changes in the behaviour of humans and livestock associated with hotter drier weather and heatwaves. During these periods, visitors and livestock are observed to be more highly concentrated around water bodies, with higher numbers of people and dogs entering the water. This can increase recreational disturbance, direct habitat damage, and pollutant load (e.g. from dogs).

Mitigation and Adaptation Opportunities

In general, measures to mitigate the impacts of climate change are largely the same as those needed to improve the ecological status of freshwater habitats, i.e. more effectively protecting our freshwater habitats from pollution, restoring natural flow wherever possible, retaining or increasing shade and natural features within channels, and creating new ponds and freshwater features across the landscape to increase resilience and connectivity.

For rivers and streams, important measures include ensuring availability of refugia such as deep pools and large woody debris and, depending on the location, either maintaining or increasing riparian shade. Warming is highest along stretches of open river exposed to direct solar radiation (insolation), the effects of which propagate downstream. As temperatures increase, reducing insolation becomes increasingly important.

Managing ponds for climate resilience needs to reflect the specific setting and characteristics, recognising that the wide variety of pond types found in the New Forest is a key feature that makes these habitats so valuable for biodiversity.

Ongoing work that is contributing to adaptation includes wetland restoration and habitat creation via the HLS and SSF projects.

Links to resources and further reading

• New Forest Freshwater and Wetland Habitats Restoration: Strategy 2019. (Hill et al., 2019)
• Storyboard created by the Freshwater and Wetland Restoration Forum
• Rivers Trust https://theriverstrust.org/key-issues
• Grantham et al., (2019) identify measures that address variability, heterogeneity, connectivity and work at catchment scale.
• The Environment Agency (2023b) report provides case studies and a review of measures to support wildlife during high and low flows.
• Keeping Rivers Cool Project: EWCO - Keeping Rivers Cool Riparian Buffers | Forestry Commission Open Data website

2.1.4 Peat Bogs and Valley Mires

The New Forest contains the largest concentration of valley mires in lowland Europe, as well as seepage mires and fens. They are diverse habitats with varying moisture, nutrient, and acidity levels, which drive the vegetation types that are found. The carbon-rich organic matter that accumulates under wet, anoxic conditions forms peat, or peaty soils that play a nationally important role in carbon sequestration as well as regulating the flow of water.

Figure 11: Map showing peat bogs, valley mires and fens within the New Forest boundary + 1km buffer (dotted line). Sources: Natural England Priority Habitats (Wetlands), Environment Agency catchments.

Sensitivity to Climate Change: High
Adaptive Capacity: Low
Risk Rating: High
Confidence: Medium

Summary

• These habitats support specialist species, many with narrow hydrological requirements that are sensitive to changes in the quality and quantity of water supply and its seasonal availability.
• Due to the limited availability of this habitat in central southern England, dispersal opportunities for species dependent on these habitats are limited.
• Reliance on precipitation, and potential for succession to a different type of habitat under a warmer and drier climatic regime, makes the overall risk for these habitats high.

Relevant sections of the Natural England & RSPB Adaptation Manual are lowland fens (sensitivity rated high), lowland raised bog (sensitivity rated medium) and Purple Moor-grass and rush pastures (sensitivity rated medium).

Context

Peat bogs are a type of wetland which is waterlogged only by direct rainfall; peat-forming bog systems are referred to as mires¹³. The seasonally (in some areas permanently), waterlogged bogs and valley mires of the New Forest rely on continuous grazing to prevent dominance of Purple Moor-grass Molinia caerulea and succession to willow and birch scrub and woodland. Associated specialised plant and bryophyte assemblages are dominated by a range of Sphagnum mosses, as well as vascular plants adapted to waterlogged conditions; these include carnivorous plants such as sundews and butterworts that have evolved to survive in low nutrient environments by feeding on insects (Chatters, 2024). Some of the specialist plant and invertebrate bog species are biogeographically isolated at a national and/or regional level, e.g. Marsh Gentian Gentiana pneumonanthe, Bog Orchid Hammarbya paludosa, Slender Cottongrass Eriophorum gracile, Great Sundew, Drosera anglica, and Black Bog Ant Formica picea.

¹³ Briefing#1 at https://www.iucn-uk-peatlandprogramme.org/resources/briefings

Impacts of Climate Change

Temperature and precipitation have a controlling influence on peat-forming vegetation, in particular Sphagnum mosses (bryophytes) which are critical components of peatland ecosystems, due to their role as ‘ecosystem engineers’ favourably modifying their immediate environment and facilitating the accumulation of carbon in the soils.

There are numerous studies into the sensitivity of Sphagnum mosses to climate change showing that they are vulnerable to warming especially when combined with restricted availability of water. The condition of peatland habitats also influences their sensitivity to climate change. Degraded peatlands, that have been drained or otherwise compromised, have higher sensitivity to climate change than intact, functioning peatlands, due to their reduced ability to absorb and regulate water flow.

Paleo records reveal variations in the rate that peat formed in the past, showing that this was driven by climatic shifts, accumulating most in warmer periods. These records show minimal or non-existent growth during drier periods coupled with an ability of Sphagnum species to recover and continue to accumulate peat when hydrological conditions are favourable. This suggests that Sphagnum will grow more as the temperature rises provided there is enough moisture. This is cautioned by a note that the ability of bogs to recover from a dry period now is not certain as historic bog formation was not subject to the additional modern pressures of peat-cutting, drainage, and variable grazing intensity (Carey, 2015). Work by Bragazza (2008) in an alpine context identified an irreversible desiccation threshold for sphagnum moss of < 6.5 mm/°C (mean monthly precipitation to mean monthly temperature ratio).

Bioclimatic envelope modelling has been used to map the potential future distributions of UK peatlands under climate change, indicating as much as an 84% retreat under high emission scenarios (Ritson, 2025). This work aligns with the assessment made in the UK’s 3rd climate risk assessment (Betts & Brown, 2021) which reported that at 4°C warming, large areas of UK peatlands could cease to be viable.

Although annual average precipitation volumes in the New Forest are not expected to change significantly, seasonal patterns are projected to be markedly different. This suggests that the future of these habitats in the New Forest will depend on how effectively precipitation can be retained within the landscape, and whether the volumes that are retained are sufficient to prevent irreversible damage during extended periods of hot, dry conditions.

When peat soils dry, Sphagnum and other mosses become less abundant and vascular plant cover increases, supporting the growth of more woody, shrubby vegetation which impacts species composition. Increasing pressure from generalist dominant species is anticipated. If allowed to grow, species such as Purple Moor-grass Molinia caerulea, Heather Calluna vulgaris, and Silver Birch Betula pendula will intercept rainfall, increase transpiration, and encourage the development of flow paths associated with root systems. This may in turn heighten the risk of wildfire damage and subsequent erosion. In an unmanaged fire, dry peat will burn along with surface vegetation and can be extremely difficult to extinguish.

Drying of peat soils increases the potential for oxidation, followed by a release of nutrients further driving composition changes. Hotter summers increase evapotranspiration, compounding the effects of drought, including increasing concentrations of pollutants such as nitrogen. There is some evidence that warmer temperatures and fluctuating water tables increase microbial activity to release stored carbon (Wentworth, 2022).

Under very wet conditions there are risks of increased nutrient inputs from in-washed sediment and run-off which will increase the stress on communities reliant on nutrient-poor conditions and may drive composition changes. Flooding and extreme wet weather increase the risks of peat slippage and erosion and directly hamper management activities.

Mitigation and Adaptation Opportunities

Increasing the resilience of these habitats to climate change requires restoration of natural hydrology (removing drainage, re-wetting) to slow the flow of water through these habitats, and the reduction of other pressures such as pollution from the atmosphere (nitrogen) and from road and other run-off sources.

Further Reading

• The IUCN UK Peatland Programme provides access to a large body of information on peatlands https://www.iucn-uk-peatlandprogramme.org/

2.1.5 Coastal and Estuarine Habitats

The New Forest coastline is dominated by sheltered mudflats and muddy gravels, with extensive areas of saltmarsh and grazing marsh. Interspersed within these habitats are stretches of shingle and sand, soft cliffs, and a small number of saline lagoons contained by spits or seawalls (HCC, 2025). Although only covering a small area of the National Park (2-3%), coastal habitats, particularly mudflats, saltmarshes, and lagoons, are designated for their internationally important populations of overwintering waders and wildfowl, along with nationally important seabird colonies nesting on the shingle spits and offshore islands. The coastal area of the New Forest is designated under local (LNR, SINC, Wildlife Trust Reserve), national (NNR, SSSI), and international (SAC, SPA, RAMSAR) conservation designations.

Figure 12: Coastal habitats

Sensitivity to Climate Change: Very High
Adaptive Capacity: Low
Risk Rating: Very High
Confidence: High

Summary

• Coastal and estuarine habitats are at risk due to sea-level rise, which is linked to increased rates of coastal erosion and coastal inundation. In locations where inland migration of coastal habitats is constrained by hard defences, the coastal strip can be ‘squeezed’ leading to loss of habitat. Habitat loss can also occur via natural coastal processes that may be exacerbated or modified by climate change. There is potential for marine and coastal habitats to expand.
• The Western Solent, bordering the length of the New Forest coastline, has experienced significant habitat degradation losing hundreds of hectares of saltmarsh, seagrass, and oyster beds over the recent and historic past. Although restoration projects are underway¹⁴, saltmarsh extents are projected to continue to decline (e.g. Thurstan et al., 2024, Parry, 2022).
• Climate change threatens all the coastal habitats of the New Forest and wider Solent, not only through rising sea level but also from rising sea and air temperatures, changing patterns of precipitation (which influence water levels and flood risk), ocean acidification, saline intrusion, and indirect risks such as pollution release from the exposure of coastal landfill sites through higher water levels and erosion.
• For estuarine habitats, potential risks include habitat loss due to sea-level rise, modified river flows with impacts on freshwater-seawater mixing, changes in sediment transport, habitat composition, biodiversity, and the fluxes of nutrients, pollutants, pathogens, and viruses.
• Hotter, drier summers, and milder year-round conditions are expected to increase recreational pressures on these internationally important sites for wildlife.

Relevant sections of the Natural England & RSPB Adaptation Manual are Coastal floodplain and grazing marsh (sensitivity rated medium), Coastal saltmarsh (sensitivity rated high), Saline lagoons (sensitivity rated high), Maritime cliffs and slopes (sensitivity rated high), and Coastal vegetated shingle (sensitivity rated high).

¹⁴ E.g. https://solentseascape.com/ and https://www.bluemarinefoundation.com/projects/solent/

Figure 13: New Forest coastline showing Environment Agency Flood Risk Zones 2 and 3 in blue, the distribution of coastal habitats, and the current shoreline management plan policies.

Impacts of Climate Change

Sea-level rise along the coast of the New Forest is projected to increase from the current trajectory of ~0.5 m to as much as 1.0 m by the 2080’s, relative to the 1981-2000 baseline¹⁶. Regardless of action to reduce emissions, sea levels will continue to rise for centuries (Stokes et al. 2025), the extent to which will be governed by ocean warming and ice melt. Exploratory sea-level rise projections are now available that extend to 2300¹⁷.

Sea-level rise increases coastal erosion and inundation, (flood) risk, and (nationally) is contributing to a decline in the extent of saltmarshes, shingle beaches, and sand dunes that act as a natural buffer to flooding (Haigh et al. 2022).

Flooding affects coastal species and habitats through frequency of saline inundation, which may be temporary (e.g. due to a storm surge) or permanent (e.g. due to a planned or unplanned breach of coastal protection), and is heavily controlled by coastal topography. In the New Forest, vulnerable habitats include the coastal grazing marshes, which are dominantly terrestrial/freshwater features and the coastal (saline) lagoons. Changes in precipitation patterns, coastal inundation frequency, and rising temperatures have the potential to modify the salinity and chemistry of the lagoons, which may alter suitability for a range of species, and facilitate the spread of invasive non-native species.¹⁸

As with terrestrial habitats, as conditions change the composition of coastal plant and associated species will evolve, although due to natural inertia and in the absence of disturbance, existing vegetation (notably dominant species) can have a strong intrinsic resistance to displacement which will manifest in a time-lag response (Burdon et al. 2020, Betts & Brown, 2021).

Saltmarsh habitats

Saltmarsh habitats are a particularly critical coastal habitat that have been declining across the Solent for decades (see Figure 14). They provide multiple ecosystem functions including coastal protection through accretion of sediments, pollution and carbon sequestration, and recreational benefits for a wide range of coastal users. They also support wildlife including breeding waders and wildfowl, provide habitat for specialist plants and invertebrates, and nursery sites for fish.

Figure 14: Historical change in saltmarsh extent for the western Solent (figure from Parry, 2022).

Saltmarsh losses within the New Forest are attributed to internal dissection (i.e. widening and lengthening of creeks) exacerbated by sea level rise, and large losses due to seaward edge erosion, representative of coastal squeeze. Chatters (2024) describes how the vegetation has evolved from seagrasses Zostera spp. and mud, to expansion and then contraction of cord-grasses (Spartina spp.)¹⁹ None of the New Forest SSSI saltmarshes are in favourable condition (Parry, 2022).

If saltmarsh has space to migrate and sediment supply is sufficient, and if wind-wave regimes do not significantly change, then saltmarsh is capable of sustaining growth, potentially maintaining pace with sea level rise. If the rate of sea-level rise is greater than the rate of sedimentation, saltmarsh will continue to erode and eventually disappear. Due to coastal protection work to the west of the Solent, natural sediment movement processes are impaired. Parry (2022) provides a timeline of when New Forest coastal saltmarsh is expected to disappear under current rates of loss.

If storm frequency increases, saltmarsh erosion will be further exacerbated as storms naturally erode and remove sediment. Fragmentation, as observed in the saltmarshes of Keyhaven, Lymington, and Beaulieu (as noted by Parry, 2022) also accelerates loss (“fragmentation is particularly destructive to saltmarsh as the deepened gullies can remove large areas of saltmarsh sediment and leave the remaining marsh less stable, thus allowing elevated tidal flows to further break up the marsh”). Loss of saltmarsh leads to loss of habitat and with that carbon storage, and ongoing carbon sequestration.

Extreme Events

Coastal change tends to be driven by extreme events that can cause dramatic modification in very short timeframes. A recent update to future storm and wave projections found that there could be an increase in the number of very severe winter storms crossing the UK as a result of climate change. The tendency of the UK to experience storm clustering, with typically less than two weeks between successive storms, has the potential to compound the impacts of these events (Bricheno et al. 2025).

Hurst and Calshot Spits are key features of the New Forest coast, with Hurst in particular providing storm protection. The Hurst to Lymington Strategy review has generated a large body of evidence on the impacts of sea-level rise associated with this stretch of the New Forest coast. The ‘Do Nothing’ scenario report (JBA, 2023) describes the impacts of coastal defence failures which are linked to age but significantly exacerbated by sea level rise. Figure 15 shows potential change in coastal habitats under a ‘do nothing’ scenario for coastal management of Hurst Spit, this is based on a breach of sea defences in 2036 and shows habitats landward of the defences experiencing a transition to more saline habitats following the breach (i.e. changes that would occur gradually from 2036 through to ~2122, which is the timeframe considered in the assessment) (JBA, 2023).

Figure 15: Current coastal habitats (left) alongside projected habitats under a future ‘do nothing’ scenario (right), (JBA, 2023).

Erosion rates of maritime cliffs (such as those found at Lepe) are expected to increase in response to increased periods and intensity of rainfall as well as rising sea level. Although the dynamic processes of erosion are critical to the specialist invertebrate and plant communities that these habitats support, their response to accelerated rates of change is uncertain.

Shingle habitat is relatively rare and therefore recolonisation rates by vegetation communities following extreme event disturbances such as storms are uncertain. Long-term change is also anticipated in these habitats in response to increased temperatures and changes in precipitation, especially due to the poor water retention of these environments leading to greater impact of summer droughts (Burdon et al, 2020).

Coastal change has potential increasing risks for coastal communities and visitors, although the frequency and consequences of flooding have reduced over time due to improvements in flood defences, as well as developments in flood forecasting, emergency response, and spatial planning (Haigh et al. 2022). Of the nine Category 5 or above coastal flooding events recorded in the UK over the past 150 years, three affected the Solent region²⁰ (Kovats & Brisley, 2021).

Impacts on Estuaries

Climate risks to estuaries vary according to their specific physical and biological conditions. In general, alongside habitat loss from sea-level rise, climate change is influencing and will continue to drive changes in freshwater-seawater mixing, sediment transport, habitat composition, biodiversity, and the fluxes of nutrients, pollutants, pathogens, and viruses (Robins et al. 2015). Altered river flows could increase the risk of eutrophication, hypoxia, and harmful algal blooms, although the risks for New Forest estuaries may be low.

Increased temperatures may increase microbial pathogen concentrations and increase public health risk, and changes to the salt balance may impact species reproduction. Rising sea levels combined with periods of low river flow increase the risk of saltwater intrusion into the upper zones of estuaries, with potential implications for ecosystem function and associated habitats and species. Little et al. (2022) define this as estuarine squeeze, reflecting the loss of upper estuarine tidal freshwater and low salinity zones against in-channel man-made barriers.

Mitigation and Adaptation Opportunities

Anticipating and planning for coastal change is vital. There is a large body of work addressing options associated with the shoreline management processes and ongoing coastal research. The Channel Coastal Observatory (CCO) provide local expertise and a rich time-series of data and analysis.

The Natural England and RSPB Climate Adaptation Manual notes the need to adjust boundaries and interest features of protected sites as coasts evolve, and the potential to enlarge functional units to increase resilience.

Efforts to restore or improve coastal habitat condition increase resilience to climate change. This includes eliminating or reducing any non-climate pressures such as pollution and disturbance and addressing as far as practicable physical modifications that have detrimental effects on coastal processes.

Further Reading

• Shoreline Management Plans for the Western Solent
• Lymington to Hurst Strategy https://www.hurstspit2lymington.co.uk/
• Solent State of Nature Report Solent State of Nature Report | Solent Seascape Project
• The Solent Forum provide useful introductory information on coastal habitats and invasive non-native species
• Marine Climate Change Impacts Partnership evidence Reports (includes coastal)
• Channel Coastal Observatory (CCO) - channelcoast.org

2.1.6 Heathland

The New Forest contains the largest area of lowland heathland in the UK, covering around 24% of the area of the National Park (12,234 ha). It is particularly important for the diversity of its habitats and the range of rare and scarce species which it supports (Natural England, 2025). The majority of heathland (89%) lies within the Crown Lands managed by Forestry England.

Figure 16: Heathland (Natural England Priority Habitats Inventory) showing the Crown Lands boundaries in green.

Sensitivity to Climate Change: High
Adaptive Capacity: Low
Risk Rating: High
Confidence: Medium

Summary

• Wet and dry heathland are sensitive to changes in temperature and precipitation.
• Climate change impacts will depend largely on how the changing precipitation patterns evolve. If overall annual precipitation rates remain similar (as suggested by current projections) the projected wetter winters may regulate or limit the potential consequences of hotter drier summers.
• Under hotter, drier conditions there is potential for wet and humid heaths to become drier, with associated changes in their species composition. Equally, if winter precipitation outpaces reductions in summer rainfall there is potential for wet heath to transition into mire. These types of adaptation have consequences for heathland specialist species (McCullagh et al., 2025).
• Heathland habitats are highly important for birds, reptiles, and several invertebrate groups, and support specialist communities such as rare bryophytes.
• Heaths are highly combustible. Wildfire risks are increasing, particularly in the south-east of England. This increases the risk of temporary heathland habitat loss.
• Although the heaths of the New Forest are managed through a combination of year-round grazing and a prescribed burning regime, neither of these management interventions are sufficient to prevent potential modification of community composition in response to the projected patterns of climate change.

The latest assessment led by Natural England (Staddon, 2023) concludes that both wet and dry lowland heath is highly sensitive to climate change regardless of condition. Relevant sections of the Natural England & RSPB Adaptation Manual (published 2021) are Lowland heathland (sensitivity rated medium).

Context

The extent of heathland in England has declined by ~70-80% over the past 300-400 years, mainly driven by changes in land use. Remaining areas of heathland, particularly in the lowlands, have become highly fragmented, divided by roads and separated by mixed land use. Heathland degradation is also linked to drainage, inappropriate vegetation management, and nutrient enrichment (McCullagh et al., 2025).

The heathlands of the New Forest occur across a gradient of moisture, from very dry conditions on nutrient poor, acidic mineral soils through to wet, shallow peats (<30 cm deep). Wet heaths feature bog-mosses (Sphagnum spp.), Cross-leaved Heath Erica tetralix, and Purple Moor-grass Molinia caerulea, and support specialist lichen communities that depend on periodic fires to survive (Chatters, 2024). Dry heaths are characterised by low nutrient, acidic soils supporting a mixture of dwarf shrubs such as Heather Calluna vulgaris, Bell Heather Erica cinerea, and gorses Ulex spp., with herbaceous vegetation, lichens, and bryophytes. These areas form a dynamic habitat which represents the succession from bare ground (e.g. after burning or tree clearing) through to grassland and/or mature, dense heath with scrubby patches.

Heathlands in the New Forest are particularly important habitats for plants, bryophytes, invertebrates, reptiles, SAC features and bird species noted within the Special Protection Area (SPA) designation including breeding Dartford Warbler Curruca undata, Nightjar Caprimulgus europaeus, and Woodlark Lullua arborea.²¹

The New Forest has long been recognised as an ecologically important area in which the most complete spectrum of heathland fauna stands the best chance of survival, with the potential to function as a ‘biodiversity bank’ supporting re-colonisation of other viable sites. (Tubbs, 2001).

²¹ https://sac.jncc.gov.uk/habitat/H4030/

Impacts of Climate Change

The sensitivity of heathlands to changes in temperature and precipitation creates risks to their long-term survival, especially in southern England where heathland habitat is highly fragmented. Although the habitat is not expected to be lost in the foreseeable future, a marked shift in community composition is possible.

Hotter, drier weather will tend to modify the species assemblage, particularly on wet heath. Carey (2015) suggests that drier conditions will result in the disappearance of remnants of wet heath dominated by bog-mosses and Cross-leaved Heath, although the latter may be replaced by other Erica species.

On dry heath there is a (low) risk of transition to dry acid grassland. This pressure is exacerbated by increased nitrogen availability, which together with warmer temperatures and drier conditions encourages grass species, e.g. Purple Moor-grass, to become dominant over dwarf shrubs such as Heather and Bell Heather (NE and RSPB, 2021). In the New Forest given the relatively low levels of nitrogen deposition and projected increase in autumn and winter precipitation, this is not considered a likely scenario.

Changes in precipitation, frost, and fire will likely alter the amount of bare ground, which will impact plant assemblages through modified regeneration/recruitment of annual plants from the seed bank. This may favour stress-tolerant (e.g. deep rooted) and ruderal species due to the increased gaps/bare ground in swards. Summer drought may favour annual species over perennials, and oceanic/sub-oceanic species may decline e.g. Bird’s-foot Ornithopus perpusillus, Heath-bedstraw Galium saxatile, and Sand-spurrey Spergularia rubra.

Both wildfire risk and the duration of the wildfire season will increase as temperature (and recreational pressure) increase, especially on dry heaths during periods of below average precipitation and drought. Dry acid grassland will potentially replace dry heath in the event of significant fires (Carey, 2015). Hot, dry conditions also lead to drying of soils and increased erosion risk, while higher temperatures also drive an increase in decomposition, which can lead to CO2 release.

Hotter summers have the potential to drive increased visitor numbers. An increase in unmanaged access could lead to local damage to vegetation, increased risk of wildfires, and increased disturbance and predation of ground nesting birds. Local experience from recent dry spring-summer periods shows that, under drought conditions, areas of the New Forest that are normally waterlogged and inaccessible become accessible to both people and generalist predators.

Very wet winters impact heathland management. The exceptionally wet winter of 2023/24 had a major impact on the prescribed burning programme, with only ~5% of the planned area completed (noted in 2024 Open Forest Advisory Committee Minutes). Changing breeding bird phenology in early spring can lead to overlap with delayed management activities in spring.

Mitigation and Adaptation Opportunities

In the short to medium-term, addressing existing pressures on heathland (such as fragmentation, isolation, management, hydrology) will increase resilience to climate change (McCullagh et al., 2025). Active management of heathlands is essential for above-ground vegetation dynamics, but also for maintaining below-ground soil nutrient and carbon pools (Gliesch et al., 2024). Ensuring optimal management and adapting management to reflect changing growth characteristics (modifying grazing or burning regimes where practicable) increases resilience.

Effective management of wildfire risks is increasingly critical including ensuring wildfire management and mitigation plans are co-ordinated and joined up across the landscape as far as possible.

Further Reading

McCullagh, F., Alonso, I., Hedley, S., Crowle, A., Diack, I., Glaves, D., Key, D., Mousley, S. 2025. Definition of favourable conservation status for heathland. RP2977. Natural England. https://publications.naturalengland.org.uk/publication/6212544182878208

2.1.7 Acid Grassland and Road Verges

Acid grassland occurs alongside heath on nutrient-poor soils, where the regime of year-round grazing and trampling creates a mosaic of short vegetation and bare ground. As with heathland, acid grasslands can be dry or wet.

Grass road verges are also included in this section, some of which are acid grassland, particularly within the SSSI. Outside the SSSI there is a diverse range of habitat types, mainly influenced by adjacent land use, including both non-designated verges and Road Verges of Ecological Importance (RVEI’s²²). RVEI’s are a Hampshire County Council designation for verges that support a notable species or provide a species-rich semi-natural habitat. They are subject to a modified cutting programme that aims to maintain biodiversity. Verges support important plant species and provide forage, habitat, and habitat connectivity for wildlife.

Sensitivity to Climate Change: Low
Adaptive Capacity: Moderate
Risk Rating: Low
Confidence: Medium

(map shown overleaf/below)

Summary

• Acid grasslands are rated as having low sensitivity to climate change, in part because many of the constituent species are adapted to challenging conditions. The main risk is drought, although increased duration and intensity of winter inundation of wet grasslands may lead to changes in species assemblages.
• Road verges have not been rated separately (or mapped explicitly due to data availability). Sensitivity to climate change is likely to be highly context specific (location, species present), and will be influenced by prevailing management, and presence of other pressures.

Relevant sections of the Natural England & RSPB Adaptation Manual are Lowland dry acid grassland (sensitivity rated low)

²² https://www.hants.gov.uk/landplanningandenvironment/environment/biodiversity/informationcentre/roadverges

Figure 17: New Forest acid grassland extent, road verges are not shown as no land-cover class exists. Note that some mixed acid grasslands and heathlands are classified as heathland on the land-cover maps as shown on Fig. 18.

Context

Acid grasslands can have a high cover of bryophytes, and parched acid grassland can be rich in lichens. Parched acid grassland also contains a significant number of rare and scarce vascular plant species, many of which are annuals. As well as supporting several priority bird species, e.g. Woodlark, this habitat supports specialist invertebrates which do not occur in other types of grassland. For example, open, parched, acid grasslands on sandy soils support a considerable number of ground-dwelling and burrowing invertebrates such as solitary bees and wasps.

Nationally there are ~313,500 miles of rural grass road verges, equivalent in area to the total remaining lowland species-rich grassland in the UK. They support an estimated 700 species of wildflower and provide refugia and habitat connectivity for many different species (Bromley et al., 2019). Anecdotally, many road verges around the Forest fringe provide vital refugia for wildflowers and their associated species (e.g. invertebrates) that are unable to survive in adjacent intensively managed grasslands. Opportunities to maintain and improve the condition of these habitats has the potential to boost biodiversity and increase climate resilience of grassland supported species.

Outside the SSSI, grass verge biodiversity value is reflected through local designation of selected verges as ‘Road Verges of Ecological Importance’ (RVEI’s). These are an initiative of Hampshire County Council to recognise verges with important botanical communities and modify management (i.e. mowing regimes) to protect and enhance their botanical value. Hampshire has an estimated 13,000 ha of roadside verge habitat (see footnote 22).

The HLS programme has supported a programme of verge restoration within the Crown Lands over several years.²³

²³ https://www.hlsnewforest.org.uk/protecting-new-forest-verges/verge-restoration/

Impacts of Climate Change

Grasslands are relatively resilient to climate change, however, as temperatures increase, and precipitation patterns change, there will be changes in the species assemblage. For example, phenology may change significantly, with flowering and seed setting occurring earlier in season, while there may be a shift to southern temperate and Mediterranean continental plant species. Bracken Pteridium aquilinum and Bramble Rubus fruticosus agg. may spread and dominate some areas. Early growth in response to warmer temperatures is likely to be offset by parching during dry summers reducing summer forage for livestock. Wet winter conditions can lead to increased poaching and damage of grasslands and their associated soils.

Mitigation and Adaptation Opportunities

• Use of adaptive management to respond to growing and ground conditions e.g. additional capacity for back-up grazing to increase flexibility in the timing and intensity of grazing.
• Increasing the extent of dry acid grassland by restoring semi-improved grasslands and re-creating habitat on improved grassland and arable land will support resilience, enabling buffering of existing sites and improving connectivity.
• Managing, protecting, and creating refugia areas to mitigate the impacts of extreme heat and drought on species, considering shade, micro-topography, disturbance, pollution (e.g. nitrogen levels) and species diversity. Ensuring that these are under optimal management. Allowing growth of scattered scrub, especially on drought-prone sites can increase the range of microclimates and soil conditions.
• Aiming to increase topographic and hydrological heterogeneity when identifying potential restoration or habitat creation sites.
• Monitoring and controlling the spread of potential native and non-native invasive species.

Further Reading

• Definition of Favourable Conservation Status for Lowland Dry Acid Grassland (RP2945)
• Buglife page
• Plantlife pages on Road Verges

2.1.8 Woodland

Broadly, woodland types found within the New Forest can be grouped as: pasture woodland, riverine woodland, bog woodland, and silvicultural inclosures, with varying sensitivities to climate change depending on tree species and local setting including e.g. soil type, topography, and exposure. For all woodland types adaptive capacity is limited due to the slow rate of regeneration.

The New Forest is particularly notable for its ancient woodlands and veteran trees which are important for rare and specialist woodland-associated species. These habitats have been continuously wooded since 1600 and have extremely high ecosystem service value both culturally and ecologically. Due to their age and life histories these ancient woodland sites are irreplaceable. Their features include a range of native, naturally regenerated tree and shrub species, old trees and deadwood, woodland flora, and rich and undisturbed woodland soils (Read, 1999).

The woodland assessment has been split into three sub-groups to enable the variations in sensitivity and adaptive capacity of different woodland types to be discussed and reflected in the spatial assessment. The sub-groups considered, and rationale for their selection is as follows:

• Old growth pasture woodland (alternatively referred to as ancient and ornamental woodland). This type of woodland has extremely high cultural and ecological importance, is irreplaceable and is unique in the UK due to its extent and provenance
• Riverine and bog woodland, assessed separately due to the high quality of this habitat in the New Forest, it’s rarity and ecological importance, and because climate change impacts include significant modification to seasonal precipitation.
• Other woodland types have been grouped together, this includes SSSI native woodland (ungrazed), managed native woodland outside the SSSI, managed conifer plantation, trees within the landscape (e.g. hedgerows, gardens/urban settings) and other woodland sites that encompass a variety of management regimes and species.

Woodland Type: Old Growth Pasture Woodland — Sensitivity to Climate Change: High; Adaptive Capacity: Very Low; Risk Rating: Very High; Confidence: Medium

Woodland Type: Riverine and Bog Woodland — Sensitivity to Climate Change: Moderate; Adaptive Capacity: Low; Risk Rating: Moderate; Confidence: Medium

Woodland Type: Other Woodland — Sensitivity to Climate Change: Moderate; Adaptive Capacity: Low; Risk Rating: Moderate; Confidence: Medium

Figure 18: National Woodland Inventory dataset, with the ancient woodland areas shown in light green.

Summary

• Climate change influences woodland growth and survival rates.
• Increased temperatures extend the growing season but also create favourable conditions for new and existing pests and diseases to thrive. Trees affected by ‘water stress’ are more susceptible to pests and diseases which could drive increases in diseases, e.g. Phytophthora disease of alder (Phytophthora alni)²⁴. Pest and disease risks are one of the least predictable risks, and potentially one of the greatest impacts of climate change on woodland habitats. Pest and disease risks are increasing.
• Non-native mammals such as Grey Squirrel Sciurus carolinensis, Fallow Deer Dama dama, Sika Deer Cervus nippon, and Muntjac Deer Muntiacus reevesi are expected to benefit from climate change, increasing the risk of stress and damage to existing trees and reducing the potential for natural regeneration to succeed.
• Alongside increased pest and disease risk, the other primary concern for New Forest woodland is drought, with the greatest impacts on woodland dependent on or defined by surface water availability such as lowland Beech and Yew, and wet woodland. In general woodland habitats with a ‘dry’ nature such as wood-pasture, parkland, and lowland mixed deciduous woodland are expected to have a relatively lower sensitivity to climate change (Staddon, 2023).
• Climate risk varies by species and is influenced by a wide range of very localised factors including the provenance of individual trees, soil conditions, location and surrounding environment, stand size, and exposure to aggravating pressures.
• Increasingly, as temperatures rise, and precipitation patterns are modified, suitability of species in this region will change. Prolonged and increased frequency of drought is likely to drive changes in the dominant tree species and ground flora with consequences for species assemblages. The rate at which these habitats evolve will depend on how precipitation patterns change and how these impact water levels in localised areas. Hotter drier summers may be countered by wetter winters but could still lead to species composition changes.
• Extreme and unseasonal weather increase stress and mortality rates. Extreme events could increase the loss of veteran trees leading to an increase in deadwood dependent species in the short to medium term before potentially decreasing if the host species is lost from the habitat altogether.
• Impacts of climate change are expected to be seen first in young and newly established trees, and as conditions change further, street trees and trees in hedgerows. This is likely to be followed by more widespread declining tree health (in climate sensitive species), increasingly difficult establishment, and increased mortality of mature trees due to both direct and indirect impacts. Even where the composition of the tree canopy remains unchanged, the composition, structure and character of the ground fora may change significantly.
• Woodland provides an important role in natural flood, erosion, and water quality management and therefore could play an important role in managing flood risks and drought, with opportunities for habitat expansion and creation.

Relevant sections of the Natural England & RSPB Adaptation Manual are lowland mixed deciduous woodland (sensitivity rated low), beech and yew woodland (sensitivity rated medium), wet woodland (sensitivity rated medium) and wood pasture and parkland (sensitivity rated low).

²⁴ https://www.forestresearch.gov.uk/tools-and-resources/fthr/pest-and-disease-resources/phytophthora-disease-of-alder-phytophthora-alni/

Context

Depending on the dataset used, somewhere between 36% to 40% of the New Forest is wooded, with about two-thirds of this being broadleaf woodland. About 75% of the ancient woodlands in the New Forest are in public ownership, with most managed by Forestry England but also including the Langley Wood National Nature Reserve managed by Natural England. The remaining 25% is split across a mix of eNGO’s and private landowners, including the RSPB (e.g. Franchises Wood), Hampshire and Isle of Wight Wildlife Trust (e.g. Royden Woods) National Trust (Deazle Wood), larger private estates and smaller private land holdings.

There are also a significant number of trees outside woodlands e.g. in hedgerows, gardens, and urban settings²⁵.

Around 40 native tree species are commonly found within the New Forest (increasing to 136 if hybrids and apomictic species are included), predominantly Oak, Beech, Birch, Holly, Hawthorn, Willow, Alder, Ash, Hazel, Rowan, Whitebeam, Lime, and Hornbeam (Newton, 2010, Chatters, 2024). Non-native species, including those planted for commercial timber, include Sycamore, Sweet Chestnut, Red Oak and Scots Pine alongside other conifer species such as Corsican pine, Douglas Fir, Lawson Cypress, Sitka and Norway Spruce.

Some areas of the New Forest are managed for commercial forestry and timber production; where these areas are in public ownership the plans and long-term vision are published (i.e. the Forestry England 2019 – 2029 Plan²⁶), for privately or trust owned woodlands management plans are not openly accessible. UK policy for ancient woodland sites includes a presumption towards conservation, and ambition for restoration where sites have been planted with non-native species, or where ancient wood pasture and parkland has been infilled.²⁷

Trees, whether within or outside woodlands, play a crucial role in in the functional ecology of the New Forest ecosystem, providing habitat structure within or on which other flora and fauna exist whilst contributing to ecosystem processes that directly or indirectly support other flora and fauna.

Whilst native trees are generally considered to provide greater ecosystem value, non-native species also contribute to wildlife conservation. This is through the provision of breeding or roosting places for birds, bats, or invertebrates, providing a substrate on which important plant, lichen or fungi species may occur, or by contributing to geomorphological and hydrological processes.

Forests and woodlands are recognised for hosting the majority of the world's invertebrates, and highly diverse understudied groups such as soil bacteria, fungi, nematodes, protists and mites which alongside forest dependent pollinators and saproxylic beetles play crucial roles in ecosystem function (Rivers, 2023).

²⁵ Trees Outside Woodland Data accessible via Forest Research here

²⁶ https://www.forestryengland.uk/forest-planning/new-forest-inclosures-forest-plan-2019-2029

²⁷ https://www.gov.uk/government/publications/keepers-of-time-ancient-and-native-woodland-and-trees-policy-in-england/keepers-of-time-ancient-and-native-woodland-and-trees-policy-in-england

General impacts of climate change on woodland habitats

Climate change both directly and indirectly increases threats to woodlands, both those managed for commercial timber, woodlands managed for wildlife and conservation, and trees outside woodlands. Assessing the risk for woodland habitats in the New Forest has been more challenging than other habitat classes due to conflicting literature - whilst some authoritative literature suggest risks are low, other references suggest that risk may be high (or very high) due to the relative exposure of this region to warming and drought stress, as well as proximity to Europe increasing the risks of new disease arrivals.

Forest Research state that climate change impacts on woodland are “…likely to be most serious and apparent in southern England, particularly on the more freely draining soils.” (Nicoll, 2025)²⁸ Rivers et al. (2023) suggest that the indirect risks associated with climate change from invasive species, pests, and diseases are expected to pose a greater threat to tree species than direct impacts from climate change.

The range of different impacts of climate change on woodland habitats are discussed below (primarily based on Atkinson, 2022):

Increased growth in response to higher levels of atmospheric CO2. Where water is not a limiting factor, tree growth rates for most species are predicted to increase as a result of longer growing seasons, increased warmth, and the rising level of CO2.

Altered suitability of tree species. Different woodland types and different species vary in their sensitivity to climate change. As average climatic conditions shift, the suitability of tree species also changes. For example, by 2050, under a high emissions scenario, species such as Silver Birch, Alder, Beech, and Sessile Oak become marginal or unsuitable for the projected climate of southeast England.²⁹ The implications are that these species will suffer higher mortality and lower growth rates, and in the absence of intervention overall woodland health and ultimately ecosystem function will suffer.

Changes in phenology. It has been widely recorded that there has been a general trend of earlier budburst across the UK in recent decades for several tree species. Analysis of the Marsham and Coombes phenological time series shows that bud burst of Pedunculate Oak in southeast England occurred about two weeks earlier during the period 1985-2000 compared to pre-1950 (Vitasse, 2022). Nature’s Calendar³⁰ and the annual Met Office led ‘State of the UK Climate’ reports³¹ provide further evidence of phenological shifts.

Earlier bud burst leads to an extended growing season, however, there is a trade-off between earlier budburst and the risk of damage from a late spring frost. If the growing seasons starts earlier and finishes later the risk of damage from frosts may not decrease and might increase. The risk will depend on whether minimum daily temperatures increase consistently, or whether they become more variable so that at critical periods in the year frosts will still occur, which is more likely in the near term.

There is also potential for cascading impacts on other woodland flora. Leafing phenology directly influences the amount of light penetrating the canopy, which can be a limiting factor on the rate of growth and reproduction in the ground flora. If phenological changes disrupt the characteristic chronology of spring emergence then this may lead to changes in species composition (Roberts, 2015).

Increased wildfire risk, especially in locations with high recreational use. Wildfires are expected to become an increasing factor affecting the condition and longevity of some woods and forest areas. (Forestry Commission, 2020). Woodland habitats considered high risk for wildfires are young coniferous stands of pine, spruce or fir, and plantations of eucalyptus or cypress. Broadleaved, mixed, and yew woodlands are usually considered low-risk habitats, although young or newly planted broadleaves will be at risk of substantial damage if there is combustible ground vegetation (Atkinson, 2022).

As the majority of UK wildfires are ignited by people (unintentionally), adjacent habitat types and recreational use are important contributing factors to overall risk.

Stress and damage from drought. Drought can drive physiological changes in trees leading to reduced tree growth, crown dieback, and mortality. Timing influences consequences: dry springs affect current year growth; late summer droughts may have a greater impact on subsequent season’s growth. Repeated droughts can have cumulative effects, leading to growth reductions several years later. The impact of drought conditions is exacerbated by heatwaves that