The Yorkshire and Humber region contains some of the most diverse and important habitats and species in Britain. The Pennine Upland and North Yorkshire Moors contain the largest extent of upland heathland of any region in England, along with extensive areas of blanket bog. The lowlands of the region support substantial areas of lowland heathland and, more localised but still regionally important, areas of wetland habitat, including small mires and fens. The region contains one of the most extensive areas of low lying floodplain in Britain, associated with the Humber Estuary. This is internationally designated for its important wetland habitats, rare species of birds, mammals and fish and significant wintering and migratory bird populations. The region has an extensive coastline ranging from chalk cliffs to subtidal rock habitats and associated species. Lowland areas are characterised by extensive areas of arable farming, hedgerows and parkland, with nationally important concentrations of Ancient Woodlands in West and South Yorkshire and around Helmsley. The region also contains chalk wolds and the limestone habitats of the Yorkshire Dales. Both provide unique and rare calcareous grassland and associated species, with the upland areas also supporting over half of the UK’s limestone pavement resource. In addition the region supports small, but internationally important hay meadow and pasture habitats.
Description
Upland habitats
Upland heath
The upland areas of the region contain extensive areas of heathland, representing 28% of England’s total (Defra, 2000). Heathland has suffered fragmentation and decreased extent due to grazing pressure, artificial drainage, invasion by bracken, increased levels of burning, and afforestation. Heathland has an associated assemblage of bird species, some of which are priority species in decline, for example black grouse which is one of the most rapidly declining species in Britain.
Upland bog
The upland moors of the Pennines and North York Moors contain areas of blanket bog. Active raised bogs, of which those in the Humberhead Levels are amongst the largest in England, are one of Europe’s rarest and most threatened habitats (scheduled under the Habitats Directive and listed as a UKBAP priority habitat). Upland bog acts as a carbon sink and can also reduce the effect of flooding and drought through water storage. Current pressures on upland bogs include land drainage, burning, grazing and in some localised areas, recreational pressures. Bird species associated with upland bog have also shown declines, including snipe, lapwing, curlew and Dunlin (Natural England, 2008).
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© Peter Roworth / Natural England |
Upland woodland
Large wooded areas have been lost over the centuries due to clearances for stock grazing and others have been converted to plantation woodland. Remnants of woodland, believed to have existed since before AD1600, are now classed as ‘ancient’. UKBAP priority woodlands in the region’s uplands include: wet woodland (alder and willow), upland ash woodland (especially important in limestone areas), upland oak woodland. In addition there are also extensive coniferous plantations such as those in the North York Moors. Some issues relating to plantation forestry, and in particular links with economic activity, are addressed in the Business and the Economy section. Woodlands and the timber they produce are of crucial importance in the global carbon cycle. They can also reduce the impacts of flooding, acting to intercept rainfall, increase infiltration into the ground, and help to increase temporary storage capacity in floodplains. They can also help to bind and stabilise soils, preventing sediment and nutrient loss during flood events; and can ameliorate local climatic extremes. Woodland connectivity (as with all semi-natural habitats) is also important to species and habitat resilience. It allows species to adapt to change where ranges may alter due to climate change, minimising the affects of isolation and fragmentation.
Upland grassland
Grassland also stores carbon, although not to the same extent as blanket bog or woodland. Most unimproved grassland (i.e. not improved for agriculture) is located in the Pennines, though significant concentrations also occur in the Yorkshire Wolds and Derwent Valley. The region’s remnant hay meadows, which are largely managed by ‘traditional’ methods, support a very diverse flora. Of 610ha of good quality upland hay meadows in England, many are in North Yorkshire (Manley, 2003). The uplands of the Pennines and North York Moors also contain 20% of the UK’s total calcareous grassland resource.
Upland surface waters
The sources of the main rivers of the region are found in the uplands. Upland rivers are typically cool, fast flowing, highly oxygenated and high in energy, providing unique habitat for salmonid fish species (where present), white-clawed crayfish, aquatic mosses, liverworts and stonefly. Upland reservoirs, managed by Yorkshire Water, also provide habitat for grebe, geese, swans, moorhen, coot and red kite (http://www.yorkshirewater.com/recreation).
Yorkshire Dales National Park
The Yorkshire Dales are renowned for its extensive limestone (karst) landscapes, which include intimate mosaics of bare limestone rock, limestone pavements (a UKBAP priority habitat), lime-rich lakes, outcrops, scree and cliffs, caves in the Ingleborough area (Craven District), quarries and calcareous flushes and grassland. The Craven uplands contain over half of the UK total of limestone pavements in Britain. The moorland areas of the Yorkshire Dales contain extensive areas of blanket bog and heathland. Associated bird life includes hen harrier, peregrine falcon, merlin, curlew, golden plover, northern lapwing, ring ouzel, whinchat and Eurasian widgeon. The Yorkshire Dales supports a large proportion of the region’s internationally important species-rich unimproved hay meadows.
The park is also home to one of the last English strongholds of the red squirrel, a UKBAP priority species, which is found around Hawes (Richmondshire District). Fragmentation of woodland and unsympathetic management, including the planting of large-seeded tree varieties, add to the current threats it faces. Woodland habitats include nationally important areas of upland ash wood, wet woodland, upland oakwood, parkland and conifer plantation.
Pressures on biodiversity in the Dales include under-grazing, over-grazing and intensive sheep grazing, artificial drainage, water course pollution (e.g. synthetic pyrethroids and fertilisers), non-native invasive species (e.g. signal crayfish, grey squirrel, Himalayan balsam), recreation (e.g. footpath erosion and uncontrolled heather fires), and continued habitat fragmentation and loss through intensive farming and inappropriate management.
North York Moors National Park
Heather moorland, a UKBAP priority habitat forms the majority of upland habitat in the park, and is maintained by grazing hefted flocks of sheep. The moors also contain blanket bog as well as marsh, streams and ponds. Within the park there are also mixed ashwood, oakwood and wet woodland priority habitats. Valleys, which lead from the upland moorland plateau, are mainly grassland with traditional hay meadows rich in wildflowers in valley bottoms. There is a large amount of woodland in the south and west of the Park, including a nationally significant concentration of Ancient Woodlands around Helmsley, and the large coniferous plantations north of Pickering (Ryedale District).
Peak District National Park
Around one fifth of the Peak District National Park’s 1,400 km2 lies within the Yorkshire and Humber region, within Kirklees, Barnsley, and Sheffield Districts, but is administered from the East Midlands Region. It contains fragmented areas of limestone heathland and blanket bog. Species present include curlew, lapwing and twite (whose population is of grave concern nationally). It contains important areas of oak and birch wood with small areas of wet woodland, parkland and veteran trees. These specific habitats generally transition into rough grazing, unimproved pasture and remnants of hay meadow, rich in flowering plants, grasses and associated wildlife. The Peak District contains limestone dales consisting of wood, heath, grass, scrub and rock which due to inaccessibility have not been agriculturally improved.
Lowland habitats
Lowland heath
Lowland heath is a UKBAP priority habitat historically maintained by burning, grazing and turf extraction. It supports a number of notable species including adders, woodlark, woodpeckers, skylark, nightjar and a number of invertebrates. A number of areas throughout the Yorkshire and Humber region were historically exploited for more intensive agriculture, coal, steel and urban development, which has resulted in significant losses of lowland heath. Restoration programmes such as ‘The Coalfield Heathland Project’ and ‘Restoring the Heaths of the Vale of York’ aim to re-connect this fragmented habitat to allow species movement between sites, and improve habitat quality by thinning woodland and removing bracken.
Lowland grassland
Yorkshire and Humber includes important grassland habitats such as calcareous grassland associated with the Yorkshire Wolds; this now covers only 1.3% of its former area, and is a UKBAP priority habitat. Associated grassland species such as burnt orchid, field gentian, purple milk-vetch and slender bedstraw, chamomile, black veined moth, Duke of Burgundy butterfly and small blue butterfly have all declined in numbers. Roadside verges now act as important refuges for species as well as providing networks along which they can migrate. This has increased the importance of areas which fall more directly under local authority maintenance regimes.
The other, and internationally significant, area of lowland grassland is the Lower Derwent Valley. It represents one of the most important examples of lowland flood meadow in the country. As well as suffering ‘traditional’ threats associated with an increasingly intensively farmed landscape it is also particularly susceptible to changes in the frequency, timing and duration of flood events – both in terms of its botanical features and feeding and wintering bird populations.
Finally there are highly fragmented lowland grassland habitats across west and south Yorkshire, often occurring in peri-urban and post-industrial contexts, and which suffer a peculiar mixture of pressures from horse grazing, to fly-tipping, pollution and development.
Lowland Woodland
Lowland woodland includes areas of secondary woodland on post-industrial (typically mine waste) sites, woodland regeneration on lowland heaths, widely scattered game cover woodlands in intensively farmed lowland agricultural landscapes, historic parks and gardens in both rural and urban settings, some plantation woodland on ancient woodland sites and small amounts of ancient semi-natural woodland and wood pasture The biodiversity value of this suite of woodland types is hugely variable and depends as much upon their wider context as their intrinsic biodiversity.
Urban and brownfield land
Brownfield land often contains pioneer grassland habitat, heaths, pools and unmanaged flower rich grassland. “Open mosaic habitats on previously developed land” is a UKBAP priority habitat. Plants associated with this habitat include moss, lichen and declining countryside species such as bee and fragrant orchid, royal fern, lichens and petalwort (a European protected species). Bird species associated with urban and brownfield land in the region include the ringed plover, song thrush, willow tit and linnet; forty invertebrate species are only found on brown field sites, 18 of which are UKBAP priority species (Natural England, 2008). Urban and parkland trees also provide important ‘ecosystem services’ such as filtering air pollution, absorbing carbon dioxide, and intercepting rain and surface water run off. They can provide shelter and cooling, reducing the urban heat island effect and can also reduce the loss of heat from buildings in winter.
Lowland wetlands
The lowlands contain important wetland areas typically associated with the floodplain of the main rivers which ultimately drain to the Humber Estuary. Wetland was once more extensive but has been drained to reclaim the land for other uses. These wetlands include fen areas fed by surface and groundwater; flood meadows; grazing marsh; reed beds; open water (natural, agricultural and post-industrial) and ditches and mire. Lowland raised bog and fen are both UKBAP priority habitats. Lowland bogs support specialised plants including sphagnum moss, vascular plants like cotton grass and insectivorous plants like sundews. Reedbeds are important for species such as bittern, marsh harrier and bearded tit. Bogs also support unusual invertebrates in the region with Thorne and Hatfield Moors (Doncaster District) supporting nationally important rare peatland species including the mire pill beetle. Pressure on lowland wetland includes habitat isolation/fragmentation, water pollution, land drainage and inappropriate water level management. Water stress due to drainage and abstraction is also an issue in the region (Defra, 2007a).
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© Peter Roworth / Natural England |
Lowland surface waters
The lowland areas of the region carry the floodplains of the main rivers, a UKBAP priority habitat, which support aquatic plant species such as water crowfoot, water starworts, lesser water parsnip, water cress and brooklime.
Humber Estuary
The Humber Estuary is of international importance, designated as a Special Protection Area (SPA), a Ramsar wetland and a Special Area of Conservation. It is the largest British coastal plain estuary along the North Sea coast, and drains one fifth of England’s water. All the region’s main rivers drain into it. The Estuary is one of the top ten sites in Europe for wintering waterfowl, internationally-important for Brent geese, golden plover, lapwing and knot and is known for rare and important mammals and other species on the inter-tidal sands, mudflat and saltmarsh. Pressures on the Humber Estuary include coastal squeeze, impacts on the sediment budget, the geomorphological structure and function of the estuary (due to flood defence works, dredging, and the construction, operation and maintenance of ports, pipelines and other infrastructure), and pressure from additional built development.
Yorkshire and Humber coastline
Most of the coastline is designated as a sensitive marine area due to its important habitat, in addition to the numerous national and international conservation designations of the Humber Estuary. The coast includes the high cliffs at the edge of the North York Moors and chalk cliff at the edge of the Yorkshire Wolds which includes Flamborough Head with its sea caves and reefs. It is also an important sea bird colony and gannetry and designated as a Special Area of Conservation due to its reef and submerged and part submerged caves.
Other coastal habitats within the region include vegetated shingle, salt marsh, coastal dunes. Over 11% of Britain’s saline lagoon and mud flat is located around the Humber Estuary.
Pressures on the Yorkshire and Humber coastline predominantly relate to coastal squeeze, resulting from the natural erosion of the coastline and the desire to protect development on land.
Soil micro-organisms and biodiversity
It is important to note that the fate of terrestrial biodiversity in the region is heavily dependent upon the impact that climate change has on soils and soil micro-organisms. Soil micro-organisms include bacteria, archaea, micro fungi and algae. They cycle nutrients in soils, breaking down organic matter and releasing carbon dioxide and oxides of nitrogen, as well as fixing carbon and nitrogen in soils for uptake by plants. Impacts of climate change on this crucial element of all terrestrial habitats are the subject of ongoing research, but are likely to vary between areas and habitats.
Functional ecological networks
Functional ecological networks represent an approach to landscape management and nature conservation that ensures linkages between important habitats are considered alongside the distribution of specific habitat patches. These networks provide a framework for ensuring species survival in landscapes under increasing pressure from short-term threats, including land use intensification and associated habitat loss, as well as longer-term climate change. Species need to be able to disperse and colonise alternative locations should their existing areas become unsuitable. Many species do not require continuous habitat in order to disperse across a region, but can move between habitat patches. However, the great majority of flora and fauna can only move relatively short distances, and so dispersal of species can only be expected where semi-natural habitats are closely linked.
The Ecological Habitat Network maps produced by Natural England illustrate the extensive and almost continuous connectivity of semi-natural habitats in the upland parts of the region. By contrast the maps also highlight that across most of the lowland parts of the region wildlife habitats are often completely isolated, providing little opportunity for species to disperse and re-colonise as existing habitat niches come under threat.
The Habitat Network maps also show that the Yorkshire and Humber region contains a high proportion of the largest woodland habitat networks in England. These are mainly located in West and South Yorkshire and around Helmsley. These areas are characterised by steep sided valleys that link the lowland vales with the upland moors, and encompass a wide range of aspects, soils and habitat types. The future sustainable management of these valleys and the woodlands they contain will become increasingly important in helping wildlife to adapt to a changing climate.
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© Peter Roworth / Natural England |
Vulnerability / impacts
Climate change models predict different outcomes for biodiversity. This is not surprising given the complexity of interactions between different species, and between species and the wider habitats they occupy. Although the subject of considerable ongoing research, it is clear that those species which can disperse and colonise different areas easily will have the advantage over those which cannot.
In general the direct key impacts of climate change are likely to be:
- Changes in the timings of seasonal events (phenology), potentially leading to a loss of synchrony between species and the availability of food, and other resources upon which they depend;
- Shifts in suitable climate conditions for individual species (their climatic niche) leading to changes in both abundance and range;
- Changes to habitats and ecosystems such as:
- altered water regimes;
- increased rates of decomposition in bogs and higher growth rates in forests (Defra, 2007b); and
- changes in the composition of plant and animal communities;
Regional impacts have been determined using available information. There is a lack of information about biodiversity in some areas and long-term monitoring can be patchy or non-existent. It is therefore recommended as an overarching action, which would enable better understanding of the impacts of climate change and inform adaptive action, that information collection and collation relating to biodiversity is improved. This should particularly address its location, extent and rate of change. Greater understanding of the current situation will enable more refined adaptations to be developed at the generic level and tailored to particular situations.
The England Biodiversity Strategy provides, as required by Section 41 of the Natural Environment and Rural Communities (NERC) Act, 2006, a list of ‘Habitats of Principal Importance’. These are all the habitats in England that have been identified as requiring action in the UK Biodiversity Action Plan (UK BAP). All of the habitat types have the potential to be affected by climate change to a greater or lesser extent. Approximately 35 of these habitats are present within the Yorkshire and Humber region, of which 13 and are considered particularly susceptible to climate change (pers comm. Richard Wilson, 2008). They are:
- Coastal saltmarsh;
- Maritime cliff and slope;
- Intertidal mudflats;
- Saline lagoons;
- Eutrophic standing waters;
- Ponds;
- Rivers;
- Mountain heaths;
- Coastal and floodplain grazing marsh;
- Lowland fens;
- Lowland raised bogs;
- Reedbeds;
- Upland flushes, fens and swamps.
Twelve of the ‘Habitats of Principal Importance’ are also felt to have a particularly significant extent in Yorkshire and Humber (pers comm. Richard Wilson, 2008). These are:
- Upland heathland;
- Arable field margins;
- Upland calcareous grassland;
- Saline lagoons;
- Upland hay meadows;
- Limestone pavements;
- Blanket bog;
- Subtidal chalk;
- Intertidal chalk;
- Upland mixed ashwoods;
- Upland oakwood;
- Subtidal sands and gravels.
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© Peter Roworth / Natural England |
Upland habitats
Upland heathland impacts
Heathland is located on thin mineral soils or peat. Increased temperature is likely to lead to an increased range of temperature experienced at the soil surface. Combined with lower rainfall in summer months, this could result in soil moisture stress. Peat may be more resilient due to its water storage properties; however, its vulnerability to other stresses, for instance increased erosion from recreation or flooding, is expected to increase. The MONARCH project (UKCIP, 2001) predicts that climate change will severely restrict the distribution of upland heath species in the Pennines. It has also looked at the impact of species which are at their southern limit in Britain and concluded that heathland is a particularly vulnerable habitat. Species such as dunlin and golden plover are particularly susceptible to climate change. Some species, including dwarf willow and trailing azalea are predicted to disappear from the Pennines and North York Moors by 2050 (Smithers et al, 2007).
Defra research indicates that plant species in these habitats are becoming more diverse, altering the composition of upland habitats, and that there is likely to be an encroachment of general species into upland habitat and a consequent decline in specialist species.
Upland woodland impacts
Upland woodland is associated with thin acidic soils. The climate model predicts that soil moisture will typically reduce by approximately 10% relative to present day; this is a function of increased temperature in summer months which, combined with lower rainfall, is likely to lead to soil water stress. Heavy winter rainfall is likely to change soil structure and content, and may reduce root connectivity within soils, especially in more open or isolated stands. ‘Top dying’ of Norway spruce (caused by severe water stress as a result of adverse climatic conditions chiefly mild, windy weather during the dormant period reinforced by drought in the first part of the growing season) will increase and it could cease to be a productive species in England (Forestry Commission, 2002). Soil waterlogging could increase in winter months due to increased rainfall and this could combine with extreme wind events to increase tree fall, although it should be noted that natural tree fall can also increase biodiversity below the tree canopy. During summer periods there may also be an increase in pathogens and cracking of timber due to drought (Forestry Commission, 2002).
Upland oak woodland and coniferous plantations occur in the uplands of the region. Earlier spring budding is likely to occur as well as some dieback due to soil stress. The distribution of upland trees may expand to higher altitudes, however other pressures, such as pests, and species being out-competed, may arise. Species associated with oak woodland include hay-scented buckler fern, a UKBAP priority species that is likely to be confined to the Pennines as a result of a vertical migration in response to temperature rises through its present range.
Other potential climate change impacts upon woodland include:
- Altered dynamics in the exchange of nutrients between tree stands and soils;
- Some pathogens, such as thermophilic rust fungi on poplar, will favour warmer summers and their effects will become more widespread;
- Insect vectors of pathogens, and other pests with direct effects, are likely to extend their ranges;
- Drought will favour those fungi whose activity is determined by host stress, as that stress increases, and will also create conditions more favourable to foliar diseases such as left spot (Marsonina);
- Mycorrhizal fungi, which play a significant role in nutrient exchange, could be negatively affected by changes to soil moisture and temperature (Forestry Commission, 2002).
Upland grassland impacts
Upland hay meadows are unique to Northern England and depend on low intensity inputs, and the maintenance of cutting and grazing regimes. It is predicted that they may suffer from invasion by southerly species. Many species typical of the upland hay meadows are at the southern limit of their distribution in England and are likely to retreat northwards as the climate warms. Wood cranesbill occurs in northern England and its future climate space is predicted to occur at higher altitudes in the Pennines. The Globe flower is also found in upland hay meadows. Although its loss to date has been due to factors other than climate, its future distribution is likely to be restricted to higher parts of the Pennines, increasing its vulnerability and fragmenting its population. Defra research also highlights that other species including smooth lady’s mantle, intermediate lady’s mantle and eyebright have declined, suggesting a change to flora more typical of lowland hay meadows (a sensitive habitat type in its own right that presently occurs in the Lower Derwent Valley SAC and along the Ouse valley.
Upland calcareous grassland associated with the limestone country of the Pennines and the Yorkshire Dales (in particular in Richmondshire and Craven districts) is species rich but likely to lose some northern/upland species to be replaced by species more characteristic of lowland grasslands, as any northern expansion in its range will be limited by geology. Ingleborough (Craven District) is one of four sites in northern England supporting limestone pavements on carboniferous limestone. It has the most extensive series of limestone pavements in the UK, varying from moderate altitude to montane in character (300-640m). Given the already high altitude at which it is found, further pressure (i.e. climate change forcing its climate space higher) may lead to irrevocable losses. Lowland calcareous species are expected to spread into upland areas but management, land use and colonising ability will determine this.
Upland wetlands (incorporating blanket bog, upland flushes, fens and swamps) impacts
Each wetland has a distinct hydrology supporting it. Hydrological conditions determine the habitat and species which are found there and there is variability within and between sites. Climate change will inevitably change hydrological conditions. Increased rainfall in winter months may increase waterlogging and may prolong or change its seasonality, affecting plant communities of varying tolerance. Whilst reduced rainfall in summer months may lead to these habitats drying due to changes in the water table, spring lines and reduced groundwater.
There is a predicted overall increase in winter rainfall in the North York Moors and Yorkshire Dales areas. High rainfall sustains wetland habitats but excess rainfall associated with more intense rainfall events is likely to only increase runoff into surface water streams. In these situations heavy rainfall could enhance localised erosion risk to peat bogs, particularly when combined with other pressures such as recreational disturbance and extraction. Blanket bogs retain water and release it during dry periods; however, the extent of the resilience of bog to increased summer temperatures and a lack of available water is not known. Studies have shown the potential for accelerated release of CO2 from peatlands in warmer drier summers (Smithers et al, 2007), combined with a risk of habitat shrinkage and increased risk of fires.
Base rich fens in the Yorkshire Dales support a number of important plants which are characteristic of lime-enriched conditions. These include the nationally scarce bird’s eye primrose of which the Yorkshire Dales has a significant proportion of the UK population. Small base-rich wetlands are of very high biodiversity importance. Consequently in a recent review, upland flushes, fens and swamps has been added to the UK list of priority habitats for biodiversity action. These habitats are highly sensitive to impacts upon groundwater resources and springs.
Climate change may increase habitat and species stress overall, especially in areas where this is already an issue. Cotton grass is likely to be retained, and white-beaked sedge is also likely to do well under climate change, but habitats will be affected by a loss of other associated species. Bog myrtle shows little change while cloudberry is likely to decline in the north of England; it is possible, however, that earlier flowering may benefit its reproduction. Large heath butterfly a UKBAP species has a sparse distribution on wet peat bogs in northern England. Models predict it will initially benefit from climate change, but may lose out in the longer term as the suitability of its climate range will increase in the 2020s but decrease by the 2050s.
Upland surface waters impacts
Increasing temperature in streams will increase biological respiration and lower dissolved oxygen content, particularly during summer periods. Areas of anoxia (no oxygen) may increase. High summer temperatures are likely to reduce stream flow, and increased rainfall may flush sediments following dry periods in degraded areas, affecting water quality and species viability. The availability of water, flow conditions and water quality are likely to change, affecting the viability of freshwater habitats and species. The draft River Basin Management Plan for the Humber (Environment Agency, 2008) contains actions which seek to reduce the effect of flooding, drought and improve ecological status. Actions are reviewed for each six year planning cycle. Actions in future River Basin Management Plans will increasingly concentrate on how to respond to the impact of climate change and achieve the aims of the Water Framework Directive (Directive 2000/60/EC).
Lowland habitats impacts
Lowland heath impacts
Lowland wet heath occurs on gleyed (poorly drained) or peat soils; where conditions are very wet, mire develops. It is predicted that an increase in rainfall will expand wet heath at the expense of dry heath (UKCIP, 2001). Species such as cross-leaved heath as well as grasses, sedges and Sphagnum moss occur in wet heaths. Marsh gentian is also found in northern England. Climate modelling suggests that its distribution will remain unchanged across Britain due to the robustness of its associated species Erica tetralix. Heather could out-compete bracken and the balance of competition between heath and acid grassland will shift.
Lowland grassland impacts
Acid grassland is often associated with lowland heath and is affected by agricultural intensification, under-grazing, over grazing, afforestation and recreation. Increasing rainfall could leach more nutrients in poor, free-draining soils associated with grassland and favour deeper rooted, more drought-resistant species. Increased temperatures and soil nitrogen are likely to encourage the invasion of heathland into lowland grassland areas. However species associated with grassland such as common storksbill are predicted to expand their range.
Lowland calcareous grassland is found in the region, particularly within the Yorkshire Wolds, although the overall resource has reduced due to the intensification of agriculture. Temperature rises could increase the range of grassland species and insects associated with them. Species such as the stemless or dwarf thistle are likely to increase their ranges. It favours unshaded and well-drained habitat and is highly climate sensitive. Yellow-wort is located across parts of England, and although its range is likely to increase slightly north and westward this could be limited by a large decrease in rainfall. Distribution of Common Rock-rose, found across Britain, is also likely to increase its distribution slightly.
Lowland woodland impacts
Species such as sanicle will be significantly affected by drought as it requires a large reproductive effort in flowering, and stresses associated with drought will suppress flowering in the following season. Species such as the willow tit prefer damp, broadleaved woodland and nest in dead wood cavities, foraging on insects. Adults defend the same area in consecutive years. It has undergone loss due to: predators such as woodpecker; a reduction in dead wood through forest management; a reduction in broadleaved tree stands; and grazing pressures. While climate change may increase its potential range, the availability of suitable woodland habitat will limit it. Nuthatch breed in mature deciduous woodland and feed on bark insects. It is increasing in population and range and this is unlikely to be linked to increased habitat availability (UKCIP, 2001). Its laying date has advanced and productivity has increased; it is not known if this is due to climate change, but milder winters are likely to increase its food supply.
Arable areas impacts
Climate change is expected to put pressure on future food production. It will impact the productivity of soils, leading to increasing waterlogging in winter months which reduces soil respiration and can lead to anoxic conditions and change soil structure and content as well as micro-organism composition over the longer-term. Hotter drier summers will increase drought conditions which can result in
- friable soils eroding due to wind action (most likely affecting farms, parklands and suburban gardens on sandy soils, for example on parts of the Vale of York);
- salinisation of soils due to the evaporation and movement of salts to the surface (particularly in low-lying areas towards the coast);
- hard pan effects of drying out (notable on cracked clay soils particularly in low-lying areas) within the region) which reduces root penetration; and
- loss of soil organic matter.
Climate change may also change pest species which will affect the viability of future crop production. Global food security is under increasing risk as a result of climate change and an increase in bio-fuel crops is already re-intensifying agricultural production with more land likely to be brought into production. This will enhance cumulative pressure on overall biodiversity, which has suffered as a result of previous agricultural activity and which is likely to face increased competition for soil resources. Work by Defra (Smithers et al, 2007) indicates that vascular plant composition will change with species such as Alexander, common cudweed, asparagus, dwarf mallow, small-flowered crane’s bill, and meadow brome increasing between 1987 and 2004; drier summers and patches of bare ground have supported this change. This research has found that ancient and species rich hedgerows will be unaffected by climate change but summer drought will increase the death of trees such as beech. Non-native invasive species may thrive and their effect on this habitat is not known.
Monitoring of farming over the last 20 years shows that barley awns and apple buds are opening earlier. Agricultural habitats support a number of UKBAP priority species, including:
- 4 beetles;
- 13 birds;
- 13 butterflies and moths;
- 12 hymenoptera;
- 4 fungi;
- 7 lower plants;
- 1 mammal; and
- 19 plant species.
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© Robert Goodison / Natural England |
There is insufficient research to determine the impact of climate change upon them but it is thought that species dispersal rates can not match changes in suitable climatic area.
Further impacts include changes in phenology with a loss in synchronisation between species and food sources, an alteration in the range of species, the increasing dominance of drought tolerant species, changes in nutrient cycling and organic carbon availability, loss of physical space due to erosion and sea level rise which will impact low lying areas associated with the Humber.
Urban and brown field biodiversity impacts
Urban biodiversity contains elements of the rest of the region’s habitats and species, and climate impacts are addressed elsewhere. Gardens and parkland for example contain trees and grassland as well as surface waters such as ponds. General impacts on these species are addressed within the descriptions of other habitat types. However, there are particular concerns about the ability of existing mature trees to adapt to temperature and drought stress in summer because of an enhanced future urban heat island effect.
Increased fragmentation, combined with urban pressures such as noise, light, air quality and recreation, means that more sensitive species may also suffer more. Urban greenspaces also provides a home to non-native species. Some species which are found in gardens are already drought-tolerant, however they will face periods of increased winter rainfall and different conditions from their country of origin.
Lowland surface waters impacts (incorporating rivers, ponds and standing waters)
Water stress is already an issue for the region (Defra, 2007a). Water availability is likely to become more and more restricted as demand continues to grow, while supply, particularly in summer months declines due to lower rainfall. The draft River Basin Management Plan for the Humber contains strategic actions which respond to the need to reduce the effects of drought and flooding, and improve the ecological status of water. Predicted hotter drier conditions in summer are associated with low water flows, low water levels i.e. drought. There may also be issues associated with a reduction in dissolved oxygen (anoxia). Increased rainfall in winter and the possibility of heavy localised rainfall will increase the effect of flooding, which could lead to peaks in pollutants being flushed through the system. Flow will become more variable with low summer flow and higher winter flow affecting habitats which have adapted to less volatile conditions.
Changes in water flow, level and quality will affect freshwater habitats as well as the growth and reproduction of individual species. Species that may be affected include, great crested newt which is likely to breed earlier in the season due to milder winters. However, a loss of available ponds, as a result of drought conditions, may lead to further fragmentation of acceptable habitat.
Lowland wetland impacts (incorporating lowland fens, lowland raised bog, reedbeds and wet meadow)
Already prone to water stress, wetland areas are particularly sensitive to changes in hydrology. A decrease in rainfall in summer months may prolong an overall lowering of the water table, especially when combined with increasing abstraction pressures from existing and future development. Those areas predominantly fed by precipitation, such as lowland raised bog (of which the Thorne and Hatfield Moors complex represents the largest remnant in England), will be even more sensitive to drying out as a result in decreased summer rainfall. An increase in winter rainfall may also change or increase the seasonality of waterlogging, affecting plant species. Research indicates that the species composition of wetland will change in response to climate change, responding both directly and to hydrological change. Greater understanding of the water level dependencies of species is required to determine future habitat composition.
Defra research suggests that lowland wet meadow, already under threat from drainage, is likely to deteriorate further due to drought and also any related enhanced abstraction.
The future of marine-influenced wetlands, outside of the Humber Estuary, will be affected by predicted sea level rise. Changes in coastal erosion could increase the losses of such wetland and intertidal habitats; however they may also be influenced by other factors, suc as, increases in pollution and changes in nutrient cycling. Saltmarsh is likely to roll inland where there are no physical barriers. Changes in coastal processes may also have a detrimental impact on habitat availability. It should also be noted that habitat conservation targets will typically include ‘no net loss’ of that habitat type, i.e. there may be requirements to identify replacement habitat where coastal squeeze is considered an anthropogenic impact and is resulting in habitat losses.
Humber estuary habitat impacts (incorporating coastal saltmarsh, intertidal mudflats, and saline lagoons).
Rising sea levels will inevitably affect the shape of the Humber estuary (see the Coastal Processes section). Wildfowl use estuaries as roosting rather than feeding sites, while waders use them for feeding. The distribution of both will alter as the estuary evolves. There is likely to be a loss of salt and freshwater wetland due to coastal squeeze which will affect waders such as the golden plover and lapwing (already priority species). According to MONARCH (UKCIP, 2001) species have already shifted in the last two decades in response to weather, both in a northerly and easterly direction. Climate change could result in a further decline in non-estuarine waders with a northward shift. Colder weather, wind and rain reduce prey availability for waders. Non-estuarine waders likely to decline in numbers include ringed plover, sanderling, purple sandpiper and turnstone.
Managed re-alignment of the Humber estuary is already occurring with tidal inundation of adjacent agricultural land. However, with increased storminess comes increased erosion, and the natural processes moving sediments around our coasts will also change. As such, it is possible that intertidal flats will become sandier. This will improve habitat for oystercatchers but actually reduce habitat for other species such as redshank and dunlin. Where habitat losses occur, through for example sea-level rise associated coastal squeeze, habitat conservation targets of ‘no net loss’ may result in the requirement for replacement habitats to be identified.
Coastal habitats impacts (incorporating subtidal and intertidal chalk, subtidal sands and gravels and maritime cliff and slope)
Rocky coastal platforms will be affected by sea level rise and increases in air temperature. The chalk of Flamborough Head is predicted to suffer the most from this impact. There will also be enhanced abrasion by wave borne sediment. Vegetated shingle will be affected as will its associated species. Climate change is likely to move coastal dunes onshore with sea level rise, and inland where there are no physical barriers due to the action of wind, although this is not expected to have a significant impact on the associated flora and fauna.
Sea grass beds will be affected by sea level rise, higher sea surface temperature and storms. Higher sea surface temperature may cause dieback of sea grass, storms may uproot it, and if there are changes in pollutant loading this may also affect its viability. Changes to the sediment regime will also impact on sea grass beds.
Non-native invasive species impacts
Climate change may favour the spread of some non-native invasive species in terrestrial and aquatic habitats. Adaptation intended to increase habitat resilience for native species, in particular through enhancing habitat connectivity, may also favour the spread of these non-native species, particularly in surface waters.
| North Yorkshire | West Yorkshire | Humber | South Yorkshire |
The majority of the habitats identified at the regional level are present, to a greater or lesser extent, within all the sub-regional areas, with some obvious exceptions such as the Humber Estuary itself. In most cases the differences between projected climate changes for each of the sub-regional cells is not sufficiently different to draw markedly different conclusions with regard to impacts and adaptations. As such the majority of habitats will be subject to the generic impacts identified at the regional level, and similarly the adaptations identified alongside them will also be as applicable at the sub-regional level. Where sub-regional specific impacts and adaptations differ from those identified at a regional level they will be discussed here, otherwise comments made at the regional level apply.
Description
North Yorkshire‘s landscapes are diverse including a rich coastline, the uplands of the Pennines and North York Moors and the upland chalk of the Yorkshire Wolds. It also includes the fringe landscapes of the Pennines and the flatter vales of York, Mowbray and Pickering. The south of the area also includes the low-lying Humberhead Levels. The county is predominately rural and is mostly described as ‘super sparse’ in the Regional Spatial Strategy. There are urban areas including, Northallerton, Scarborough, Catterick Garrison and Harrogate as well as market towns throughout the county. The City of York is however mostly urban.
Upland moorland in the Dales and Moors includes heathland, rough grassland and blanket bog; the North York Moors containing the largest continuous area of heather moorland in England. The Yorkshire Dales also contains acid grassland, rock outcrop, cliff and scree as well as acidic tarns and reservoirs.
The Dales contain nationally important areas of upland ash woodland, and the Moors include a national significant concentration of Ancient Woodlands and associated Woodland Habitat Networks along its southern edge.
Both the Yorkshire Dales and Yorkshire Wolds contain calcareous grassland which is nationally rare and has become fragmented by agricultural intensification and water abstraction pressures. Other habitats include limestone rock, scree, cliffs, quarries and caves. Limestone associated species in the Yorkshire Dales includes sandwort (which is only found here and has a low dispersal ability), and prickly sedge (which is critically endangered). The Dales are also last refuge of lady’s slipper orchid. Yellow marsh saxifrage was once associated with lowland wetland but is now only found in upland areas and at its southerly extent in the Dales.
River floodplains are a prominent feature of the lowland areas as are remnants of once more extensive wetland, including flood meadows. Lowland areas also include grassland, woodland, parkland, hedgerow and arable areas as well as remnants of lowland heath and meadows. Lowland arable areas include field margin habitat as well as grassland and hedgerow. Species which are associated with lowland arable field margins include harvest mouse, hedgehog, bats, skylark, grey partridge, grasshopper warbler, spotted flycatcher, tree sparrow, linnet, yellowhammer, corn bunting, and yellow wagtail and starling.
All main rivers flow to the Humber Estuary. Surface waters include lakes, ponds, rivers and streams. Lowland fens are composed of wet ground which overlies peat and contains sedges and tall herbs.
The coast of North Yorkshire is largely within the North York Moors National Park. Habitats here consist of maritime cliffs, rock and soft shores with sublittoral habitats. Additionally the soft chalk cliffs at Flamborough Head are an important sea bird colony and gannetry, the largest sea colony in England.
Impacts
In addition to the wide-ranging impacts identified at the regional level, a number of impacts are of particular importance in the North Yorkshire sub-region. The key habitats particular to North Yorkshire are: Upland Mixed Ashwoods, Montane Heath, Upland Calcareous Grassland, Upland Heathland, Upland Hay Meadows, Limestone Pavement and Blanket Bog. Impacts include:
- Blanket bog occurs on flat moorland and is exposed to significant solar gain during hot summer months. Peat can be expected to shrink, especially in areas where there are already drainage, grazing or burning pressures, and this could lead to further breakup of peat and increased rates of peat oxidation and loss. This would have an impact on breeding bird populations, perhaps principally as a result of declines in invertebrates. Blanket bog peats would be expected to re-wet in winter months although since net annual rainfall is predicted to reduce this may only be a temporary effect.
- Fens are sensitive to changes in water level as well as pressures including conversion to forestry and agriculture, water abstraction, pollution and fragmentation.
- There is extensive heathland in North Yorkshire and models predict that some species may increase whilst others decline or disappear (eg dwarf willow). Upland heathland’s particular vulnerabilities to climate change stem from an increased risk of wildfires and the potential for greater recreational activity, as well as secondary effects of changes in agricultural practice and colonisation by woodland.
- Changes in moorland habitat will affect upland breeding bird populations which are under threat from loss and decline. It is likely that food sources will also change – perhaps particularly significant in this respect is the cranefly, the larval and adult stages of which are an important food source, and which is dependent on wet areas.
- Changes in grazing habitats, food supply and water supply are likely to impact on current agricultural practices.
- Moorland habitats are fundamentally dependent on a limited number of land management regimes and products (sheep, grouse, recreation). How these, especially sheep, will respond to climate change is unpredictable but the secondary effects of changes in agricultural systems are likely to match or even exceed the direct effects of climate change.
- Habitats such as hay meadows and upland calcareous grasslands are likely to change from their current species mix to more drought tolerant species with an increase in herbs and ruderals. The earlier on-set of plant growth relative to traditional grazing calendars may seriously impact those plant species sensitive to grazing e.g. annual species. Changes in plant assemblages will affect associated species as well as potentially silage and hay growth for livestock. In hay meadow habitats warmer summers may promote more frequent and earlier cutting, with negative impacts on ground nesting birds e.g. yellow wagtail, curlew, lapwing.
- The flush habitats associated with spring lines are obviously particularly vulnerable to declining water tables or increased water abstraction.
- Coastal habitats are prone to sea level rise and erosion which alter exposure to air and water. For example the chalk cliffs associated with Flamborough Head are soft and prone to erosion from sea level rise.
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The West Yorkshire region includes part of the Character Areas of the Dark Peak and Southern Pennines, Southern Pennine Fringe, Nottinghamshire, Derbyshire and Yorkshire Coalfield and Southern Magnesian Limestone. It therefore ranges from the Pennine moorlands of the Dark Peak and Southern Pennines with deeply dissected valleys into progressively lower and more undulating limestone landscape further east.
Upland habitats include upland heathland, both acid and neutral grassland, hay meadows and upland mixed ashwood, upland oakwood and areas of wet woodland. A high proportion of the sub-region’s woodlands are classified as Ancient, and the woodland habitat networks they form are of national significance.
Upland wetland areas are principally blanket bog with purple moor grass and rush pasture. Priority species associated with bog include bog-rosemary and marsh helleborine. Upland bird species are well represented including red grouse, dunlin, hen harrier, meadow pipit, short eared owl and merlin as well as the rare twite.
Grassland occurs across the area including acid grassland, lowland calcareous grassland, dry acid grassland, heath and meadows. Species associated with unimproved grassland include the skylark, slow worm, snipe, warblers, dark purple earth tongue, and pink waxcap, small copper and stags-horn clubmoss. Hedgerows support a wide range of species including linnet, bats, yellowhammer and reed bunting.
There is lowland mixed deciduous woodland in eastern part of the sub-region along with wood pasture and parkland. Notable species include the lesser spotted woodpecker, beaked bow-moss, pied flycatcher, dunnock, spotted flycatcher and hairy and red wood ant.
West Yorkshire impacts
Due to the wide range of habitats present in this sub-region, the wide-range of impacts identified at the regional level apply across this area, with the obvious exception of coastal and intertidal habitats. However it is worth noting the particular importance, in the sub-regional context, of upland heathland, blanket bog, woodland habitat networks and associated Ancient Woods, and a relative abundance of lowland dry acid grassland (>100ha in Wakefield).
The Humber sub-region includes a contrast in landscapes, between the high ground of the Yorkshire and Lincolnshire Wolds, and the lower lying areas of the Vale of York, The Humberhead Levels and the Humber Estuary.
The Humber Estuary is one of the largest river estuaries in England and its rivers drain about one-fifth of the country (a catchment of some 24,240 square kilometres). It is the largest macro-tidal estuary on the British North Sea coast and is the largest single input of freshwater from Britain into the North Sea. This estuarine landscape is typically bordered by the high flood banks which contain the estuary up to the point where it narrows, just west of the confluence of the rivers Trent and Ouse. Within this area the waters of the estuary itself provide the focal point of the landscape. Around it is a terrestrial landscape of very low-lying, flat farmland combined with urban and industrial development and some notable natural habitats.
It has the second-highest tidal range in Britain and approximately one-third of the estuary is exposed as mud or sand flats at low tide. The inner estuary supports extensive areas of reedbed with areas of mature and developing saltmarsh backed in places by limited areas of grazing marsh in the middle and outer estuary. On the north Lincolnshire coast the saltmarsh is backed by low sand dunes with marshy slacks and brackish pools. The Estuary regularly supports internationally important numbers of waterfowl in winter and nationally important breeding populations in summer. Its value as a conservation resource is seen in its designation as SPA, SAC, Ramsar and SSSI.
The site is a representative example of a near-natural estuary with component habitats including dune systems and humid dune slacks, estuarine waters, intertidal mud and sand flats, saltmarshes, and coastal brackish/saline lagoons.
The lower saltmarsh of the Humber is dominated by common cordgrass and annual glasswort communities. Low to mid-marsh communities are mostly represented by sea aster, common saltmarsh grass and sea purslane communities. The upper portion of the saltmarsh community is atypical, dominated by sea couch saltmarsh. In the upper reaches of the estuary, the tidal marsh is dominated by common reed and sea club rush swamp with the couch grass saltmarsh. Within the Humber Estuary Ramsar site are good examples of four of the five physiographic types of saline lagoon.
The Humber also supports internationally important populations of birds, including Eurasian Golden Plover, Red Knot, Dunlin and Black-tailed Godwit.
Outside the built-up area of Hull and the developed areas along the shores of the estuary, is predominantly arable farm land. Some grassland remains and is grazed by cattle. There are a few relic areas of salt marsh and reedbeds, along the tidal channels which cross the drained marshes, and there is also some remaining marshy grassland. The water-filled Barton clay pits, which once supplied the brick-making industry and now lie disused below the Humber Bridge, contain open water, reedbeds and other wetland vegetation and are of considerable value for birds. In the estuary itself mudflats cover extensive areas and are exposed at low water. They are of international importance because of their role in providing feeding areas for birds. Woodland cover is relatively sparse but there are a few blocks of medium-sized, regularly-shaped deciduous woodland, which are particularly prominent in the flat, open and uniform farmed landscape.
Upstream of the Humber are the Humberhead Levels. This is a predominantly flat agricultural landscape which is one of the most productive cropping areas in Britain. Some of the predominantly low-lying area is at or below the mean high-water mark. The landscape includes the broad floodplains of several major, often navigable, rivers which drain to the Humber. They include the Derwent, Don, Torne, Idle, Went, Aire, Ouse and Trent. The farmland is rich and intensively farmed in generally very large, open, geometric fields usually divided by dikes.
There are important alluvial flood meadows (Ings) which are valued for their wetland vegetation and as habitats for wintering and migrating birds. The sands still support some remnant heathland and there are also some areas of neutral grassland on clay soils which are of wildlife importance. The remnant raised mires on the peat deposits are of great importance although few areas remain which have not been affected by drainage or peat cutting.
Semi-natural habitats are extremely limited in this intensively farmed landscape and so those that remain require special consideration. This is particularly the case with raised mires; there may be opportunities to recreate areas of this habitat following peat extraction. Positive heathland management on the sandy ridges may also require incentives.
Much of the other areas within the Humber sub-region are also intensively farmed. It is predominantly arable although some pasture also occurs. There is woodland but its extent and distribution is variable. Where woods do occur they are important in providing enclosure and landscape structure. Ancient woodland is limited in occurrence. Semi-natural woodland is largely confined to steep slopes in the dry valleys of the Yorkshire and Lincolnshire Wolds, though the large wet woodland area of Bishop Wood is of regional significance. Semi-natural vegetation has largely been lost as a result of agricultural intensification and now only small fragments remain. For example, unimproved chalk grassland is today quite limited, confined to steep, dry, valley slopes, road verges, sea cliffs, quarries and road and rail cuttings. As such, many of these areas are of ecological importance. Marshland and meres were historically very common but Hornsea Mere, Yorkshire’s largest natural lake, is the only sizeable surviving example. Some unimproved neutral grassland still occurs on the boulder clays and a number of quarries and sand and gravel pits are of ecological importance.
Impacts
In addition to the wide-ranging impacts identified at the regional level, a number of impacts are of particular importance in the Humber sub-region:
- Rising sea levels could alter the form and function of the Humber estuary.
- The distributions of waders and wildfowl will alter in response to the evolution of the estuary and may affect its designated status.
- Coastal squeeze may result in losses to both brackish and freshwater wetlands. This will also affect numerous wading bird species.
- The MONARCH (UKCIP, 2001) research indicates that species have already shifted in a northerly and easterly direction over the last two decades in response to weather changes. If this continues it could result in further declines in non-estuarine waders.
- More serious storm surges may compromise Spurn Head, with unpredictable consequences.
- Several non-estuarine wading species are likely to decline in numbers due to coastal squeeze include ringed plover, sanderling, purple sandpiper and turnstone.
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The South Yorkshire sub region comprises a variety of landscape types. These range from, in the north and east, the internationally important area of the Humberhead Levels. Moving east to west there is part of the Magnesian Limestone Ridge, which bisects much of the region, the Nottinghamshire, Derbyshire and Yorkshire Coalfield area (the ‘Coal Measures’) and in the west and south, the Yorkshire Southern Pennine Fringe. Consequently, the sub region includes a wide variety of topography and landscape. Much of the rest of the sub area is characterised by rolling countryside and also includes part of the Peak District National Park.
The uplands consist of heathland, upland mixed ashwood, upland oakwood and hay meadows as well as acid grassland. Associated species include the goshawk, hen harrier, merlin, golden plover and dunlin, as well as twite. Rare flora includes the Derbyshire feather-moss and tassel stonewort.
Lowland habitats include arable field margins, lowland mixed deciduous woodland, ancient and species rich hedgerows and lowland meadow, as well as wood pasture, parkland and orchards. Habitats associated with limestone geology include calcareous grassland, caves, inland rock and chalk rivers.
Surface water and wetland habitats are diverse including rivers, mesotrophic, oligotrophic and dystrophic lakes as well as ponds. Wetland areas include lowland raised mire (the Thorne and Hatfield Moors complex is the largest remnant in England), blanket bog, fens, coastal and floodplain grazing marsh, and vegetated shingle. These all support an associated assemblage of plants and animals. Water related species include kingfisher, water vole, and white–clawed crayfish, the latter especially in upland rivers. Habitats associated with previous mining and mineral extraction include quarries, mines and gravel pits as well as the associated standing water. Urban habitats include brownfield sites, green space, derelict areas and street trees.
The easternmost part of South Yorkshire falls within the Humberhead Levels. As well as the designated sites this is a predominantly flat agricultural landscape and is one of the most productive cropping areas in Britain. Much of the area is extremely low-lying; some areas lie at or below mean high water.
Impacts
Due to the wide range of habitats present in this sub-region, the range of impacts identified at the regional level will apply across this area. However of almost unique significance are the Lowland Raised Mires of Thorne and Hatfield Moors. In addition there are significant extents of Lowland Heathland and Upland Oak Woodland, and the proportion of Ancient Woodland and the woodland habitat networks they form are of national significance.
