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STATUS OF RARE WOODLAND PLANTS AND LICHENS

1.0 Introduction

The parlous status of woodland birds and butterflies has long been recognised and there are examples that show that woodland plants have also exhibited dramatic levels of decline over the past century. This study attempts to quantify the losses of rare and threatened woodland plants and lichens, and identify the changes to which these losses can be attributed. In particular, it will focus on the threatened and near threatened and Priority BAP species in the British flora. It also covers widespread species, especially those of international significance, in Britain, where data was available.

Woodlands are a prominent part of the British landscape and are the natural

vegetation of a great deal of the land below the tree line. Woodland cover is below 10% in most parts of the UK due to millennia of woodland clearance and natural climate deterioration. The cover of ancient native woodland is even lower. The expectation would therefore be that woodland would be a premier habitat for rare plants in Britain.

Woodland is certainly an important habitat for all groups, but for different groups the relative importance varies markedly. For vascular plants and bryophytes, open habitats feature much more strongly than woodland habitats for our most threatened species. For lichens and fungi, in strong contrast, woodlands stand out as very rich habitats for rare species. The distribution of rare species within woods is also very patchy, with average woods lacking rare species, but with some specific woodland habitats and types being spectacularly rich.

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2.0 British woodlands 2.1 Types of woodland Woodlands have been classified in various ways over the past century by

ecologists and conservationists. These vary from very broad generalisations, often characterised by the usually dominant tree, such as Upland Oak Wood, to detailed phytosociological classifications, such as the National Vegetation Classification (NVC) (Rodwell, 1991) or computer-based stand classifications (Bunce, 1982).

An intermediate type of classification is the Peterken Stand Type classification of the over-storey layers in coppiced ancient woodlands (Peterken, 1993). The broad generalist classifications can be quite problematic, for instance the interest of west Highland hyper-oceanic woodlands for epiphytic lichen appears inversely related to the dominance of oak, making the names Upland Oak Woods or Atlantic Oak Woods, somewhat problematic (Coppins & Coppins, 2005). Detailed floristic classifications can emphasise widespread common features, especially in the ground flora, uniting otherwise rather disparate woodlands. For example, the NVC unites acid upland temperate zone woodlands, often with oak prominent and acid boreal birch woodlands, which never have oak, under the name Quercus petraea – Betula pubescens – Dicranum majus Woodland (W17). The frequent ground flora species are common between the two woodland types but the canopy composition and epiphytic lichen floras are different. Stand type classifications, such as Peterken’s Stand Type Classification, can express regional canopy variation in detail but are not comprehensive. Peterken Stand Types work well in the lowlands but there is a desperate need for a similar system for the uplands. Unpublished work, to allow condition assessments of woodland lichens in Scotland, by Brian and Sandy Coppins, demonstrated that a very useful classification was possible using a combination of tree and shrub composition, topography and land use, in contrast to the coppice layer composition and soil characters used in Peterken. The NVC is certainly over-used in situations where it is too generalist for the purpose; it expresses shared common features and irons out local distinctness (Rackham, 2003).

In this study it was found rather difficult to use any of the current widely

used classifications. Broad systems such as the woodland habitats defined for the Biodiversity Action Plans were sometimes too vague to easily assign species to them. Equally, full floristic or stand type classifications were too detailed to use for general conclusions. For this report, a broad but comprehensive climatic-based classification was created to help understand the distribution of species of concern within Britain. This was inspired by the climatic zonations indicated by epiphytic lichen assemblages, which change in more marked degree than do vascular plants (Coppins & Coppins, 2002).

Comment [TCW1]: Originally published in 1981. PETERKEN, G. P. 1981 Woodland Conservation and Management. London, Chapman and Hall.

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Temperate woodland: native woodland with temperate broadleaved trees such as oak and ash prominent. Within temperate woodlands the following species assemblages were recognised. These pick out distinctive regions within the temperate woodlands:

• Hyper-oceanic temperate woodland species: confined to areas of

extreme and very wet oceanic climates. These constitute distinctive assemblages of bryophytes, lichens and ferns, which occur most extensively in the western Highlands but with outliers in the Lake District and North Wales (Hodgetts, 1997).

• Oceanic temperate woodland species: species that extend into, or are

confined to, sunnier southern oceanic areas in the south west. There is a rich assemblage of southern Atlantic, or more widely distributed oceanic lichens, a distribution not reflected strongly in other groups of woodland species.

• Sub-oceanic temperate woodland species: species confined to drier

eastern areas. These include a sizeable lichen flora, now confined to clean air areas in Scotland, and a small group of vascular plants, mainly found in the east of central England.

• Temperate woodland species: species that are generally found across

the country. This group includes most vascular plants as well as significant numbers of mosses and lichens.

• Temperate – boreal woodland species: a number of species occur in

both the temperate and boreal woods, including species with hyper-oceanic, sub-oceanic and general temperate distributions.

Temperate woodlands are developed below 200 – 300m in the Scottish

Highlands. The altitudinal limit is unclear in the south, as virtually no woodland survives beyond the limit of oak here, one of the species that best defines this climatic zone. Oak woods reach to just over 400m in the Lake District and Dartmoor and native beech woods grow to up to a similar altitude in south-east Wales. Within temperate woodlands, there are strong gradients from north to south and east to west in response to increasing temperature and rainfall respectively.

Tree assemblages, however, have not reached equilibrium with the climate (Svenning & Skov, 2007); the slow post-glacial recolonisation of beech and hornbeam is particularly notable. The case of beech is especially striking; beech can easily naturalise well north of its apparent native distribution, and would probable grow at a greater altitude and further north than oak, if it reached its full potential natural range (Peterken, 1996 & Maxwell, 1929). Curiously, fossil pollen indicates that it may actually have succeeded in spreading further north and west in the past but lost ground due to woodland clearance (Rackham, 2003).

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On top of natural factors of climate, recolonisation rates and soil composition, woodland composition is also determined by changes due to woodland exploitation and management. Small-leaved lime in particular has lost ground in face of exploitation (Peterken, 1993 & Rackham, 2003). It has gone from an abundant tree across the lowlands of England and Wales to uncommon and locally extinct.

On a national scale, most vascular plant composition varies on a north to

south axis, with species numbers dropping off to the north. There are small assemblages of species that show a west to east gradient, with a few ferns confined to western oceanic woods and a few sub-oceanic woodland herbs confined to the south east.

In contrast, bryophytes and lichens in temperate woodlands show a much stronger east to west variation than vascular plants. Bryophytes and lichens have exceptionally rich and diverse assemblages of Atlantic species, dependent on strongly oceanic climates. These reach their apogees in very wet hyper-oceanic temperate climates. These conditions are most strongly developed where high mountains rise close to the western seas, as in the western Highlands, Lake District and North Wales. For lichens, there are also distinctive assemblages of sub-oceanic species in clean air areas along the east coast. These are similar to the woodland lichen assemblages of Denmark and southern Sweden.

Within all temperate woodlands, local variations between woods in

composition mainly relate to soil differences. An important axis is between strongly acid to strongly base rich soils, and another from wet soils through to dry soils. Woodlands on strongly acid soils are poorer in vascular plants species than less acidic soils. The richest woods are usually large woods with varied soil types.

A typical example would be a wood with both base rich clays and acid sands with springlines producing areas of wet woodland. Although base rich soils support species-rich communities, woods on chalk and limestone are rarely the richest woods overall as they lack acid and wet soils. An additional factor is longevity; the longer a wood has survived, the more time it has to accumulate species - ancient woodland (Peterken, 1993). For epiphytic species a continuity of old trees is also highly significant - old growth woodland (Alexander et al., 2002). Connectivity between woods also increases resilience over time (Peterken, 1993). This temporal and spatial variation is discussed further below.

Within individual woodland types, diversity is associated mainly with varied

structure producing varied light conditions. If the trees and shrubs form a full canopy, they use so much of the light there is not enough left over to allow smaller terrestrial or epiphytic species to flourish. There are a few saprophytic or semi-parasitic vascular plant specialists that utilise dark stands, especially of beech, but species diversity increases with increasing light. As well as dappled light from incomplete canopies, temporary full

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light from felling or coppicing and semi-permanent or permanent glades or rides are important promoters of diversity.

Coppicing produces particularly species rich, if temporary, communities (Rackham, 2003). Coppicing was a fundamental part of the character of lowland woodlands for centuries before the decline of the practice. It produces flushes of freely flowering woodland species and more weedy species, neither of which survive well if woodland cover does not return rapidly. In the shade phase, coppice plants survive as less freely flowering individuals or in the seed bank. It is difficult to see direct analogies with natural woodlands for the coppice habitat (Rackham, 2003). It appears to be a man-made landscape, exploited by plants evolutionarily adapted to exploit smaller canopy gaps caused by windblow or disease. Glades that are more permanent have a different flora, which is essentially that of our native grasslands and heaths. With the exception of chalk and limestone grasslands, most British grassland and heathland communities readily form from cleared and grazed woodland. There are, however, some specialist wood edge species as well. Many assemblages of now rare and declining epiphytic lichens appear to be strongly associated with glades and canopy collapse deep within old growth woodlands (Coppins & Coppins, 2005 & Sanderson, 2007a).

The issue of diversity and light is at the heart of a deep paradox within

woodland conservation. Woodlands should be among our most natural habitats, but removing man’s management results in darker woodlands with lower species diversity. In particular, there is the phenomenon of invasion by native shade-bearing late succession species such as beech and holly. These regenerate under the shade of other less shade-casting species such as oak and hazel, which themselves require strong light to regenerate. The result is that non-intervention woodlands in the western European lowlands, that have been left untouched for long periods, become species-poor beech woods (Vera, 2000). A monitored British example, The Mens in Sussex, has shown a steady decrease in species diversity since monitoring started in 1972 (Swift & Howorth, 2006). This appears to have been caused by increasing cover of beech and holly. Even the considerable windblow which occurred during the 1987 storm has failed to halt this decline.

Two key species, oak and hazel, which appear to be eventually eliminated

in non-intervention stands, were however a prominent and permanent component of natural western European woodland. It is clear that reference non-intervention stands are failing to replicate natural conditions (Vera, 2000 & Kreuz, 2007). This issue has resulted in great controversy about the exact drivers that maintain openness within natural woodlands.

Vera (2000) postulated that grazing and browsing animals were much more important in driving woodland dynamics than had been previously accepted by woodland ecologists (Peterken, 1996). Some responses to this were very critical (Mitchell, 2005) but failed to postulate realistic alternatives (Kreuz, 2007). Svenning (2002) showed that openness was even greater in previous

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interglacials and supported browsing animals as a major factor in these interglacials: most floodplains were permanently clear of trees and low productivity soils supported significant open areas of up to 30% of land cover. On mesic soils openness occurred but was less than 5% of the land cover. This suggested that the loss of very large browsing in this interglacial resulted in the grazing and browsing animals becoming a less significant driver in natural woodlands in this period. A role for grazing and browsing in driving natural woodland dynamics is now more generally accepted (Peterken, pers. com. & Kreuz, 2007), but not necessarily as dominant or all encompassing as in the more extreme interpretations of Vera’s theory.

For modern woods, the upshot is that doing nothing certainly does not

produce species rich, diverse woodlands, in the short or medium term. Reference non-intervention stands are an important scientific objective (Peterken, 1996) but do not conserve rich woodland floras. Either active management of the trees is required, or in unexploited woods, more naturalistic grazing regimes (Hodder et al., 2005) are required to prevent late-succession tree species totally dominating.

Boreal woodland: boreal woodland must once have been widespread at

high altitudes in Britain, probably above 300 – 400m in England and Wales, but falling above 200 – 300m in the southern Highlands, and to sea level in the north west. The upper limit of frequent oak is probably the most efficient definition of the beginning of zone, but the boundary is very vague. This type of woodland has effectively been lost south of the Scottish Highlands. On gentle slopes in many areas to the south, blanket bog has spread to below the upper climate limit of oak, and the loss of boreal woodland is probably natural in these circumstances. On steeper slopes, the disappearance is likely to be due to deforestation. Boreal woodland, however, is still widespread in the Highlands.

There will have been, and is, no sharp boundary between temperate and

boreal woodland; gradual transitions are the rule, especially on more fertile soils. On the dominant acid soils, the presence of pine is an obvious characteristic, and the native pine woods are deservedly famous (Steven & Carlisle, 1959). They are not, however, the totality of boreal woodland. They are replaced by other sorts of boreal woodland on less acidic soils and to the north of the current native distribution of pine.

Even the current dominance of pine in some woods, may not have been long lived. Pollen diagrams from Glen Affric, show a switch from pine-birch woods with alternating phases of canopy collapse and regeneration to pure pinewood in about the 18th century (Wolf & Tipping, 2003 & Shaw & Tipping, 2003). Other pollen diagrams show pine dominance for a much longer time, particularly in the east. However, in Abernethy Forest, although always subordinate, birch has declined in recent centuries to give the modern pure pine stands (O’Sullivan, 1975). Associated species include silver birch on lower ground, mountain downy birch Betula pubescence ssp tortuosa at

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higher altitudes, and universally in the west (Worrell & Malcom, 1998), rowan, aspen, juniper and alder. The surviving native pine woods all contain old growth stands and appear to have been within of unclosed grazing land for millennia.

Various birch dominated woods are associated with pine woods, or dominate

in areas without pine. Some may be woods from which pine was lost in the past, but many are on more fertile soils, where spruce would normally replace pines in continental boreal woods. In Scotland the place of spruce appears to be taken by mixed boreal broad-leaved woodlands dominated by silver or mountain downy birch which, when in good condition, can also contain rowan, alder, hazel, aspen, birch cherry, mountain goat willow and juniper.

These are less well known than the pine woods but can be significant for old growth dependent mosses and lichens. Examples include silver birch woods with aspen clones rich in rare species, and most of the other trees mentioned above within farmland enclosing the more fertile soil adjacent to the pine woods in Speyside. These are relatively low-altitude woodlands but higher altitude mountain downy birch woods occur on fertile soils on unenclosed hill land, typically with associated huge ancient alders, often pollards, (McVean, 1956a & 1956b & Stiven & Hole, 2004), along with mountain goat willows Salix caprea spp sphacelata, rowan and aspen. The best-known example is on the Creag Meagaidh National Nature Reserve. An exiting recent development (MacDonald, 2005), which accords with the author’s personal observations, is that many more high-altitude birch woods are at or near the natural tree line (in the sense of coherent woodland with trees over 3m in height) than was appreciated previously.

Boreal woodlands in the Highlands have greatly reduced in area since their

greatest extend about 5,000 years ago. Much of the loss since then, especially in the west, has been to the apparently natural spread of blanket bog (Davies, 2003a), with the onset of wetter climates. In western Glen Affric, Davies (2003b) shows large-scale natural decline of woodland with peat spread, especially for pine that occupied acid gentler slopes, and longer-term survival of boreal birch woods on slopes. These survived millennia of human settlement, although were finally lost in the medieval period. In the much drier Caenlochan, in Angus, pollen diagrams presented by Huntley (1981) show high altitude birch-hazel-alder woods as opened up and effected by grazing after 2,750 years before the present, but surviving until as late as 200 years before the present, when they disappeared entirely.

In the Ben Alder and Loch Treig area, an early map, the Blaeu Atlas of Scotland, 1654, appears to show extensive open woodland in the area (Smout et al., 2005). Some of these still survive (McVean, 1956a & 1956b) and have been examined by the author. They proved to be the remains of high-altitude mountain downy birch woods with rowan, mountain goat

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willow, aspen and alder on peat-free slopes, and a single surviving pine on the edge of the encroaching blanket bog. As for the native pine woods, only one mapped wood, south of Loch Leven in Lochaber, appears to have disappeared entirely in the early modern period (Smout et al., 2005). In recent centuries losses appear to have been much more severe for boreal birch woods on richer or damper soils than the native pine woods on acid soils. Until recently, almost all surviving boreal woods were heavily grazed and had little regeneration. The surviving woods, however, have been grazed for over two millennia by domestic stock, with native deer and wild cattle present prior to this, so they must have regenerated under grazing pressure many times.

Man has certainly played a large part in deforesting many areas, especially

in the east and on more fertile soils, but Fenton (1998, 2004 & 2008) has challenged the significance of this. The core of his argument is that the densities of red deer quoted low enough for adequate tree regeneration (as low as four-eight deer per square kilometre) are considerably below the natural carrying capacity of the hills for red deer, which is about 20 deer per square kilometre in the worst sort of ground. This is a result of the mild oceanic climate, which also contributes to wide-scale natural acidification and nutrient impoverishing of the soils.

Given this, the conclusion that moorland is likely to be as natural as woodland and that much deforestation would have occurred naturally, would seem difficult to refute. His position is extreme, but in the far north west, at least very credible. In less extreme areas, the facts point to natural woodland that was more strongly affected by grazing than lowland woodland, with a great deal of natural openness. This was proposed by Peterken (1996) before grazing and browsing was accepted as having any impact on lowland natural woodlands. Natural boreal woodland in oceanic Britain may have been a very distinctive, extreme type, with the less extreme winters and severely leached soils allowing natural grazing impact to be a much more significant driver of woodland dynamics, and fire much less prominent. Given this, the modern fashion for total grazing exclusion as a tool in boreal woodland restoration is questionable (Dennis, 1998), if natural or semi-natural native woodland is the objective.

2.2 Longevity and size 2.2.1 Habitat longevity Longevity in woodland habitats has been demonstrated to be a significant

factor in the richness of woodland floras (Peterken, 1993). Staring from bare ground, time is required for woodland ecosystems to fully assemble. On a very long timescale the tree and woodland herb floras appear still not to be fully at climatic equilibrium since the return of trees to northern Europe (Skov & Svenning, 2004 & Svenning & Skov, 2007). In Britain most concerns, however, are on a shorter timescale and concern recovery of woodland recolonising cleared land (Peterken, 1993 & Rackham, 2003); and conserving those woods that have survived as woodland since medieval or at least early

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modern periods. There is a rather complex nomenclature involved in describing longevity in woodland habitats with very different meanings (Alexander et al., 2002), which are listed below:

Virgin woodland: woodland never disturbed by man. It is often pointed

out that there is none of this in Britain, but equally there is little of it anywhere else. Much supposed virgin woodland in other contexts was exploited by aboriginal inhabitants in ways not immediately recognisable to Europeans. Often used as a euphemism for old growth woodland

Primary – secondary woodland: in a British context, woodland that has

never been cleared since woodlands returned, versus woodland that has been cleared but then recolonised. Outside Europe, this normally would also be old growth or virgin woodland, but in Britain the term is used for managed young growth woodland. It is not really proven that this is of much significance over long timescales. Small leaved lime has colonised Iron Age hill fort banks (Rackham, 2003); species rich woodlands can be found developed over Roman farmland on the chalk in southern England (Colebourn, 1983); and very rich woodland of medieval origin has been studied in Oxfordshire (Day, 1993).

On the other hand, there are a few species, which appear largely confined to primary woodland, but there always are exceptions (Spencer, 1990). There is certainly a lot of primary woodland in Britain, but it is difficult to distinguish from very old secondary woodland. At shorter timescales, there are much clearer differences, which are accommodated in the ancient and recent woodland split.

Ancient – recent woodland: this is currently the most frequently used

category in Britain. This distinguishes between older woodlands, pre-dating 1600AD (ancient woodland) and those post-dating this (recent woodland) (Peterken, 1993 & Rackham, 2003). All recent woodland is secondary woodland but ancient woodland can be either primary or secondary. The date is largely one of convenience. Secondary woodlands predating 1600AD are much more difficult to identify as maps are lacking and documentation spasmodic. Secondary woodlands of late medieval origins are also rare, while woodlands of post 1600AD origin are widespread. Ancient Woodland Inventories produced even younger dates (Spencer, & Kirby, 1992), with the earliest available accurate county map used, usually dating from the mid-to-late 18th century, but as late as the 1840s in some northern English counties.

Differences between ancient and recent woodland are usually very

pronounced, with a large suite of plant species proving to be slow colonisers over this timescale. This has led to the compiling of lists of ancient woodland indicator species (Peterken, 1974 & Rose, 1999). Colonisation does occur, even if slow (Brunet & Von Oheimb, 1998, Bossuyt et al., 1999 & Verheyen & Hermy, 2001) and can proceed at different rates in different habitats. For example, recent woodlands on floodplains in Belgium are

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colonised much faster by woodland species than woodland off floodplains (Verheyen et al., 2003).

The concept of ancient woodland indicator species seems to work best in the drier parts of Britain, in areas with scattered isolated woods and with recent woods originating on arable land. It works less well in wetter areas of the country, areas with interconnected woodlands, and where woodland has colonised some types of natural grassland. With numerous exceptions, it is best to regard vascular plant woodland indicator species lists as indicators of woodland habitat that is strongly associated with ancient woodland; but not as direct indicators of ancient woodland.

Ancient woodlands are now a keystone feature in woodland conservation

and woodland policy in Britain (Forestry Commission, 2005 & ODPM, 2006). They represent woodland habitats that cannot be recreated in the short term.

Old growth – young growth: ancient woodland is determined on the continuity of the site, not the trees themselves. The trees could be coppiced on a five-year rotation, but the woodland would still be an ancient woodland. This is something of an alien concept to conservationists in most other parts of the world, where such woodland would be regarded as of little consequence (Rhind, 2003). In most parts of the world, little disturbed or near natural woodlands are the main conservation issue. These are often described as old growth woodlands. These are essentially woods in which trees live out their natural lives. In many parts of the world, old growth stands are synonymous with virgin forest as old growth stands predates the start of European exploitation.

They can equally be found within cultural landscapes and be woods that were managed primarily for products other than timber, such as stock grazing or wild game (Alexander et al., 2002). Generally the term is confined to woods that are at least semi-natural and have been in an old growth condition for at least several generations of trees. Disturbed young growth woods, however, will develop into old growth woodland if left unmanaged. In Britain, most woodland types begin to develop strong old growth characteristics after a stand age of about 200 years, although hazel-dominated stands probably become old growth in about 100 years. Old growth woods are especially rich in species of lichens that are dependent on niches found only in older trees (Coppins & Coppins, 2005 & 2006, Sanderson, in prep, and Sanderson & Wolseley, 2001). As with vascular plants, indicator lists of lichens associated with high-quality old growth woodland have been drawn up (Coppins & Coppins, 2002). There are four separate indexes of ecological continuity covering different climatic

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zones. The occurrence of the species used is directly linked to old trees and continuity of this habitat. As a result the lichen indicator indexes are more of a direct measure of old growth continuity than vascular plants are indicators of ancient woodland continuity.

Although Britain may have no virgin woodland, it has a surprising large

amount of old growth woodland associated with woods that were traditionally utilised mainly for grazing, and related habitats in parklands. For example the New Forest, Hampshire, alone has as much old growth woodland as the whole of northern New England and southern New Brunswick (Flower & Tubbs, 1982 & Selva, 1994). Lowland England certainly has considerably more old growth woodland than lowland France (Rose, 1988). Only 1% of forests in Norway are older than 160 years (WWF, 2003), yet woodland cover in Norway is often compared favourably with the Scottish Highlands, where well over 50% of ancient native woodlands are probably older than this.

Much old growth within the cultural landscapes of Britain is certainly of international significance. Unlike ancient woodland, however, there has been no attempt to carry out an inventory of old growth woodland and there is no explicit protection given to old growth woodland (Alexander et al., 2002).

2.2.2 Habitat size Large areas of woodland tend to be richer in species than smaller

woodlands. This is both because larger woods harbour more varied individual habitats and because they are able to sustain larger and hence more sustainable populations of individual species.

Rackham (2003), however, demonstrates that for ancient coppices in eastern lowland England the relationship is weak for plants. These woods have been isolated for more than a millennium and have probably long reached equilibrium. Rackham (2003) suggests that the current fashion to apply island biogeography theory to English woods is pushed too far. He argues that lowland ancient coppices are suffering from far more pressing problems than millennium-old fragmentation, such as the cessation of coppicing and increasing deer numbers. This is in contrast to habitats such as fens and heathlands that have been massively reduced in area in the past 200 years, and where there are serious and real fragmentation problems.

Unlike woodland vascular plants, many epiphytic lichens show the more

conventional behaviour expected of woodland species; they avoid woodland edges and can require very large areas of old growth woodland to survive (Sanderson, 1998a & 2010). Some very interesting results produced by Ellis & Coppins (2007) showed that modern epiphyte diversity in individual aspen stands within boreal woodland, was related to woodland size in the 19th century, not to modern woodland size. Where woods have declined in area since the 19th century, then this implies a looming extinction debt. Again this suggests that fragmentation should be regarded as a priority issue in

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habitats that have been reduced in size in the past few centuries. Schemes to undo fragmentation that occurred millennia ago could be something of an extravagance.

2.3 Historic woodland management 2.3.1 Introduction The history of woodland management in relation to nature conservation

value has only relatively recently been studied in detail, with much pioneering work done by Oliver Rackham (Rackham, 1980). This was largely based in East Anglia and adjacent areas (Rackham, 1986, 1989, 1990 & 2003). Unfortunately, there was no other review of a similar level of authority based on other areas of the country until Smout et al. (2005) on Scotland and this lacks the depth of coverage of biodiversity issues of Rackham’s work. This has unfortunately led to a tendency for nature conservationists to uncritically project Rackham’s work from East Anglia on to other areas of Britain. This is in spite of Rackham’s exultations to have regard to the unique nature of every wood and not to dwell on commonplace shared features (Rackham, 2005).

2.3.2 Coppicing, timber and grazing The main historic methods of exploiting woodland are grazing (either by

domestic stock or by killing wild game), coppicing bushes or young trees for small wood with the intention of re-cutting them or felling larger trees for timber. A variant on coppicing in grazed woodlands is to pollard trees, thus protecting the regrowth from browsing.

It is likely that woodland exploitation started as a chaotic combination of all methods of exploitation, but with grazing predominant (Vera, 2000). The New Forest was a multi-use system with all the above forms of exploitation carried out in the same piece of land by competing, and often mutually antagonistic, interests in the early modern period (Reeves, 2006, Roberts 2002 & Tubbs, 2001). There seems to be a strong relationship between the density of settlement and the degree of separation between types of woodland exploitation. Areas of the country with dense settlement, with large areas of fertile land capable of arable production, tend to segregate the different uses of woodland. In particular, grazing is separated from woodland all together. This separation allowed for more efficient use of limited land resources. In contrast, areas where arable land was very limited are likely to have retained unspecialised multi-use woodland systems for far longer. East Anglia, where Oliver Rackham carried out much of his work, is very much a crowded landscape, hence it is problematic to uncritically use his work here as a template for other parts of the country.

In well settled areas of the country, fully enclosed coppice tended to

dominate woodland use at a fairly early date. If grazed at all, this would be carefully controlled and have limited effect on the woodland composition. Remaining unenclosed land tended to lose woodland altogether and moor, heath, fen and down would dominate. Where woodland survived on open land, normally forests, it would typically be in the form of

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compartmentalised pasture woodland - embanked coppices enclosed for several years after cutting but later thrown open to grazing, as in Hatfield Forest (Rackham, 1989). This did not always work well and changes to composition due to past browsing damage to coppice can be seen in surviving examples.

In less populous areas, separation of woodland uses tended to be much

weaker and grazing in particular was often all pervasive (Smout et al., 2005 & Winchester, 2000). Land use and woodland management was often much more fluid compared to the extreme long-term stability shown by many lowland enclosed coppices. The management of such complex systems was inefficient in terms of timber and wood production and, from the mind set of the enlightenment elite, irrational. From a nature conservation perspective, a major impact of such inefficient systems was that they tended to preserve old growth characteristics inherited from natural woodland. This is a key factor in the survival of internationally important old growth dependent epiphytic lichen floras in the west of Britain. Such systems have declined with modernity and, where they survive, tend to be simplified.

In the uplands, a sequence of woodland development has been shown in

several areas, where subsistence peasant farming was replaced commercial sheep farming (Winchester, 2000). The earlier subsistence farming was characterised by extensive unenclosed woodlands, cattle dominated grazing, references to ‘panage’ (feeding pigs on acorns) and extensive heather dominated moors. The switch to commercial sheep farming was associated with the loss of unenclosed woodland, disappearance of panage and replacement of heather moor by grass moor. Wales, the Pennines and the southern Uplands were in the latter condition by the end of the medieval period. The Scottish Highlands remained in the former condition into the modern period.

2.3.3 Coppice The role of coppice in traditional management within British woodlands is

well known and described (Rackham, 2003). The scale of coppicing, however, is probably not widely appreciated. Many attempts at coppice revival are rather half-hearted, with too many standards retained, the coppice stools reduced to too low a density by over shading and the ‘coupe’ (area of coppice) size much too small. The latter is very important. Much conservation revival coppicing is carried out in very small coupes of about quarter a hectare or less. In contrast, much historic coppicing was carried out by felling coupes of many hectares in extent at once. This was especially so in areas with industrial woodland industries feeding charcoal furnaces or cutting oak for tan bark. A picture (Fig 73) in Peterken (2007a) dating to before 1929 in the lower Wye valley at Tintern illustrates this well. There is a similar picture in Peterken (2007b). In the lower Wye, entire hillsides were cut at once with virtually no standards retained.

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The biodiversity impact of controlled grazing in coppiced woodlands is especially obscure, as the treatment has totally disappeared. It is likely to have favoured woodland edge and woodland grassland species.

2.3.4 Pasture woodland The role of coppice in traditional management within British woodlands is

well-known, but the extent and variety of woodland in which grazing was the predominant use is less widely appreciated. Interest in the nature conservation value of the habitat, however, has increased greatly since this was first analysed in Harding & Rose (1986). As was the case with Harding & Rose (1986), this report is considering the wider pasture woodland habitat, rather than a narrow view of ‘wood pasture’. The former term is used advisedly in this report as it covers all the aspects of extensively grazed woodland habitats. This includes grazed high forest with a woodland ground flora, park-like (savanna) stands and associated open grasslands (Chatters & Sanderson, 1994). Wood pasture, as strictly defined by Rackham (2003), is confined to trees over grassland without a woodland element in the ground flora. Rackham argues that grazing in woodland depends on there being grassland maintained under the trees. This definition excludes grazed woodland sites such as the New Forest, which Rackham has accepted is not a wood pasture under his definition (Rackham, pers. com.).

In fact, grazed woodlands historically were complex systems with competing

land users who did not always share similar aims and therefore were not necessarily logical (Tubbs, 2001 & Smout et al., 2005). In addition, shelter and winter browse within pasture woodlands were often (and in the New Forest still are) more valued than the summer grazing within the woods by graziers. In this case opening up woods to a degree that encouraged summer use would negate their greatest value in winter. Preservation of woodland almost entirely for its value as shelter for cattle seems to have been a feature of well-managed late medieval to early modern Highland estates (Watson, 1997). Where summer grazing was particularly good, typically trees would be removed altogether, producing what were often known as lawns in England. The whole system would be complicated by the wood and timber rights usually being separate from grazing rights. Neither party might be getting exactly what they wanted.

Where pasture woods were, and are, being managed sustainably, then

regeneration must occur. When it occurs it tends to occur in clumps, eventually producing a glade and grove structure but with areas of savanna produced by canopy collapse (Vera, 2000). There are also likely to be permanent open areas where the grazing is most productive. A pasture woodland consisting of nothing but savanna is a dying woodland and not a sustainable habitat. It is therefore rather odd that in some areas healthy regenerating pasture woodlands are termed ‘infilled wood pastures’ with the implication that this regeneration is damaging (Stiven & Hole, 2004).

The Wood Pasture and Parkland BAP explicitly rejected the narrow

definition of wood pasture and adopted the wider pasture woodland

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definition (Definitions Sub-group, 2001), although the misleading term ‘wood pasture’ is still used in the title.

Building on Harding & Rose (1986), the following general classification of

pasture woodland can be made with reference to the past traditional use: Lowland forests and commons: generally grazed for most of the year,

producing wood from pollards and temporary coppicing and usually significant amounts of timber. Found mainly on forests and chases but also on common land in some areas. Surviving pasture woodlands near London were dominated by pollarding, but this seems to have been unusual, and reflects distortions cased by the huge firewood market in London. In most woods, the lord of the soil had the right to grow timber, and lowland pasture woodlands were a major source of timber in early modern England (Stagg, 1989). This was the native tradition of English high forest management, but one that relied on ‘wild regeneration’ of patchy scattered regeneration occurring where it could, rather than dense carefully preserved ‘natural regeneration’. Strictly, ‘natural regeneration’ is a propaganda term from modern German foresters for the unnaturally dense and regular regeneration aimed at in shelter wood and selection felling systems of high forest treatment (Vera, 2000). Recent research in the numerous documents surviving from the New Forest (Reeves, 2006) gives vivid picture of the management of such pasture woodlands in the 17th century. The New Forest was a heavily exploited old growth woodland that still retained its old growth characteristics (Sanderson, 2010.).

Winter grazed woodlands: these were briefly mentioned in Harding & Rose

(1986), with reference to the old growth oak woods of Horner Combe, Exmoor. They were actually very widespread in the uplands of Britain, and were especially important in the western Highlands (Smout et al., 2005). Management appears to have been much like lowland pasture woodlands, but coppicing was easier without summer grazing and, while pollards are present in some regions, they are absent in others. In south west England and the Scottish Highlands, these occurred in the modern period on enclosed commons or hill grazings. In Wales and northern England most were in enclosed land, called the ffrith or out bye. In these the importance of grazing can be seen on old maps, as virtually all woodland in the ffrith and out bye fails to fit to any boundaries, whether wooded enclosures or rough grazing. In these areas there was virtually no woodland on hill commons, a great contrast to the Scottish Highlands. In many areas, a great deal of this often very mixed woodland was replaced by industrial coppiced oak plantations in the 18th and 19th centuries (Smout, 2005 & Coppins & Coppins, 2005). Given that these areas were originally grazed, it is ironic that many conservationsists do not support them reverting to pasture woodlands. Interestingly, in one of the best preserved areas of former winter grazed pasture woodland in Borrowdale, Lake District, grazing was a significant positive factor for 80% of the internationally significant bryophytes there (Thomason, 1995). In western Scotland, the impact of 18th and 19th century industrial coppicing on formerly winter grazed woodlands is variable (P. Quelsh, pers. com.). There are substantial areas of surviving

Comment [TCW2]: The irony that grazing management is being opposed when these areas were originally grazed – i.e. they were replanted as coppice in between.

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old growth woodland which were not affected but also very large areas of mixed pasture woodland where coppicing for charcoal was intensified in the 18th and early 19th centuries but which remained mixed grazed woodlands. These are now reverting to old growth woodland and are nearly as lichen rich as the woods undamaged by coppicing. In contrast, substantial areas were converted to pure oakwood (Tittensor, 1970) and remained intensively managed for tanbark until the early 20th century (Smout et al., 2005). These oakwoods are still much poorer in lichens than the other types of woodland (Coppins & Coppins, 2005).

Summer grazed woodlands: these were not described by Harding & Rose

(1986), but are a significant feature of the Scottish Highlands. They were the woodlands that survived within the summer grazings used by cattle-dominated transhumance systems in medieval and early modern periods. Most had probably been grazed for several millennia (Huntley, 1981). Tiny relicts survive in the Pennines (Fleming, 1997 & Sanderson, 2001a). These woods probably included much of the boreal pine and birch woods. They also included the more isolated temperate woodlands, particularly at the heads of inland glens.

A well-preserved example is the ten km long pasture woodland on the north east shore of Loch Lomond at Pollochro (Sanderson, 2005a). An interesting reference in Smout et al. (2005) refers to tenants of Craigroyston in 1758, to the south of Pollochro, complaining that for 11 months of the year their only pasture was in the woodlands that were about to be enclosed and converted to oak coppice. A characteristic identifying feature of summer grazed upland pasture woodlands is the presence of alder pollards (Sanderson, 1998b). In winter grazed upland woods (and in lowland grazed woodlands), alder appears to have been mainly coppiced as the species is unpalatable, and is able to recover even under quite heavy, if extensive, grazing. Many high altitude former summer grazed pasture woodlands are now in very poor condition, having failed to regenerate since the coming of sheep farming or creation of modern sporting deer forests (Maxwell, 1929) in the late 18th or early 19th centuries. They are now grazed heavily throughout the year, rather than for a few months starting from May or early June through to October at the latest (Harvey, 2002, & Winchester, 2000). As a result, the current very open condition of many of these woods is probably not representative of how they looked in their prime. There are exceptions, for example, the pasture woods at Pollochro, Loch Lomond, have younger generations of trees succeeding the oldest generation of ash and alder pollards. The woods appear to have regenerated at least twice in the 19th or early 20th centuries, with the pollards dating from the 18th century. The woods were still grazed as part of a farm when they regenerated but presumably had low deer numbers (Sanderson, 2005a). Currently these woods are not regenerating in spite of the withdrawal of farm stock but they still have significant numbers of red deer.

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Contemporaneous regeneration within such woods, as at Creag Meagaidh NNR, has only been achieved by reducing grazing to levels well below both the natural carrying capacity of the land (Fenton, 1998, 2004 & 2008) or the likely levels of summer grazing when they were summer grazed pasture woods. These woods appear to have been favoured by very low deer numbers, but quite high but seasonal stock grazing, not an easy combination to obtain in the modern uplands.

Deer parks: privately owned enclosed pasture woodlands housing deer

were prominent status symbols in the medieval period (Rackham, 2003). A few have survived as semi-natural ecosystems, with many old trees, unimproved grassland and more dense wooded patches, e.g. Dinefwr in Wales and Widen Park, Exmoor. Most, however, have been absorbed into landscape parks, a somewhat different status symbol developed in the early modern period. Few of these are semi-natural systems and the majority are artificial arboretums, although they are important reservoirs of veteran trees. Historic landscape conservation considerations usually preclude rewilding and regenerating these habitats using wild regeneration.

2.4 Methods of floristic analysis 2.4.1 Scope The analysis of the rare plant flora covers Britain, i.e. England, Wales and

Scotland and includes vascular plants, bryophytes and lichens. The species covered are those included within the most recent Red Data Books (for vascular plants - Cheffings & Farrell, 2005; for bryophytes - Church, 2001; for lichens - Wood & Coppins, 2003) and the latest list of BAP species (Biodiversity Reporting and Information Group, 2007). For lichens, an unpublished spreadsheet for the second edition for the Conservation Evaluation was used as this was digitised already, added many new species and made some obviously required changes.

Woodland species were defined as any species which appeared to the author

to have at least some of its British population within wooded habitats. There are obviously borderline species, where arbitrary decisions had to be made. Of the lower plants, epiphytes which are clearly confined to trees outside of woodland were not included in the main figures, but were considered separately.

2.4.2 Information The habitat, ecology and threats to the individual species were determined

using personal experience and mainly standard accounts such as Preston et al. (2002) and Hill et al. (1991, 1992 & 1994). The data on the National Boidiversity Network web site www.searchnbn.net/ was especially useful for researching species not well known to the author. The UK Biodiversity Action Plan website was also consulted. Many other publications were consulted, which are referenced in the text. As well as the broad climatic classification of woodland outlined in section 2.1, attempts were made to allocate species to other classifications. The woodland Priority BAP Habitats (Biodiversity Reporting and Information Group, 2007) proved

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relatively straightforward but woodland Annex 1 Habitat Directive Biotopes (European Commission, 2003) proved difficult. The data was entered into spreadsheets.

3.0 Rare and declining plants 3.1 Vascular plants 3.1.1 Red Data Book and Biodiversity Action Plan species – numbers and

distribution

Key to abbreviations:

IUCN category Critically Endangered (CR) Endangered (EN) Vulnerable (VU) Near Threatened (NT) Data Deficient (DD) Least Concern (LC)

The most recent Red Data Book (Cheffings & Farrell, 2005) is a full

assessment of the whole vascular plant flora and lists 443 species that are of Conservation Concern or Near Threatened (NT). Of these species, 48 are clearly woodland species, 11% of the total. Similarly, of the 171 vascular plants listed as priority Biodiversity Action Plan (BAP) species, 29 are woodland species, 17% of the total. This, however, includes 12 whitebeam micro-species of rocky habitats usually within woodlands, and excluding these brings the Red Data Book (RDB) species to 8% of the total and BAP species down to 11%. This explains a general feeling among botanists that open habitats harbour more rare species and are under greater threat than woodlands. This is likely to reflect the degree of protection that has been afforded to woodland in the past half century. Much has changed and been lost within British woodlands but the habitat remains widespread and the losses are small compared with habitats such as fens and heathlands. A species that exemplifies this is oxlip Primula elatior (NT), which once occurred in both meadows and woods in the small area of eastern England to which it is confined, but was lost from grassland sites by the 1930s (Preston et al., 2002). It has declined in woodlands but still survives (Rackham, 2003).

The combined total of RDB and BAP woodland species is 50. Of these, 43

are confined to temperate woodland, three are boreal species and four are found in both temperate and boreal woods. Within the species of temperate woodlands, the majority show no strong trends towards strongly oceanic woodland or to sub-oceanic areas within Britain. An exception is the single species confined to hyper-oceanic woodlands - Wilson’s filmy fern Hymenophyllum wilsonii, a small Near Threatened fern, whose low growth

Comment [TCW3]: But when compared to the other 19 broad habs, woodland is 6th or 7th from the top! (depending on if NT/DD included). This needs qualification.

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form and thin foliage renders it an honorary moss. Unlike many species, this is not an edge of range species, with Britain a core part of this fern’s world range. The lack of hyper-oceanic vascular plants in Britain is in contrast to the abundance of hyper-oceanic bryophytes and lichens. Woodland southern oceanic species are also limited, with only Italian lords-and-ladies Arum italicum ssp neglectum (NT) and bastard balm Melittis melissophyllum (VU & BAP) assigned to this group. In contrast, there are many rare southern oceanic species of woodland lichens.

Species with a strong eastern tendency are slightly more frequent, with five

species confined to sub-oceanic woodland. These include three species of southern, base rich, damp, ancient woodlands-rich woods: oxlip Primula elatior (NT), Suffolk lungwort Pulmonaria obscura (EN & BAP) and crested cow-wheat Melampyrum cristatum (VU & BAP). The other two are rather enigmatic and more northern species. May lily Maianthemum bifolium (VU) is a strongly continental small lily of acidic woodlands with a tenuous scattered distribution in the east of England, which is confused by potential garden escapes. The species has poor flowering and seed set in Britain. The British population could also conceivably be one with a low viability, which is periodically naturally introduced by birds. Whorled Solomon's-seal Polygonatum verticillatum (VU & BAP) is confined to temperate woodland in a few northern ravine woodlands in Perthshire and Angus, but is also widespread in boreal woodland in Scandinavia. It is a possibility that it once occurred in base rich boreal woodland in Britain but has been lost from this woodland type through habitat loss.

The temperate woodland species include many southern species such as

spreading bellflower Campanula patula (EN & BAP), narrow leaved bittercress Cardamine impatiens (NT), starved wood sedge Carex depauperata (EN & BAP), white helleborine Cephalanthera damasonium (VU & BAP), green hound’s-tongue Cynoglossum germanicum (CR & BAP), mezereon Daphne mezereum, pale St John's-wort Hypericum montanum, military orchid Orchis militaris (VU), lady orchid Orchis purpurea (EN), spiked rampion Phyteuma spicatum (EN) and downy woundwort Stachys germanica (VU). A northern species is lady`s slipper orchid Cypripedium calceolus (CR). Widespread species include narrow-leaved helleborine Cephalanthera longifolia (VU & BAP), lesser butterfly orchid Platanthera bifolia (VU & BAP) and greater butterfly orchid Platanthera chlorantha (NT). The majority are found in base rich habitats but spreading bellflower Campanula patula (EN & BAP), copse-bindweed Fallopia dumetorum (VU & BAP), spiked rampion Phyteuma spicatum (EN) and Arran service-tree Sorbus pseudofennica (VU& BAP) are species of acidic woodlands.

Four species grow in both temperate and boreal woods and three in purely

boreal woodland. These species are, not surprisingly, mainly northern species, but with juniper Juniperus communis (BAP) a more widespread species. Juniper, however, is only really a woodland species in the north. Coralroot orchid Corallorhiza trifida (VU), northern hawk`s-beard Crepis mollis (EN & BAP) and small cow-wheat Melampyrum sylvaticum (EN & BAP) are species of broadleaved stands found in both temperate and boreal

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woodland. Twinflower Linnaea borealis (BAP), one-flowered wintergreen Moneses uniflora (EN & BAP) and intermediate wintergreen Pyrola media (VU) are more strongly confined to boreal woodlands, especially pine woods and old pine plantations. The Linnaea and Pyrola can occur in moorland and the latter is more frequent in this habitat. Coralroot orchid Corallorhiza trifida (VU) is a saprophyte associated with trees and bushes in damp situations and uses the under shrub creeping willow Salix repens in open dune slack habitats as well as wet woodlands. It is also a good colonist of secondary wet woodlands.

VASCULAR PLANTS – SPECIES OF CONSERVATION INTEREST

Distribution within climatic regions

Habitat No. of vascular plants

% vascular plants

Temperate & temperate – boreal 39 78% Temperate, hyper-oceanic 1 2% Temperate, oceanic 2 4% Temperate, suboceanic 5 10% Boreal 3 6%

Extinctions A single species is recorded in the RDB as extinct, the enigmatic ghost

orchid Epipogium aphyllum (EX). This saprophytic orchid has a history of fleeting appearances and may spend much of its life underground. It was reported in 1986 and hence declared extinct in the 2005 RDB, but has since reappeared at a single site in Herefordshire in 2009.

3.1.2 Red Data Book and BAP Species – habitats and threats For the temperate woodland species, the strongest linking factor for many

species is a requirement for well lit conditions on wood edges, glades and in the early regrowth of coppiced and felled stands. Species strongly associated with the early regowth of coppice and similar habitats include narrow leaved bittercress Cardamine impatiens (NT), starved wood sedge Carex depauperata (EN & BAP), green hound’s-tongue Cynoglossum germanicum (CR & BAP), lady orchid Orchis purpurea (EN) and spiked rampion Phyteuma spicatum (EN). These species have been affected by the reducing of intensity of management within lowland woodlands, especially the cessation of commercial coppicing of ancient woodlands over much of the country. Some wood edge species appear to have been especially vulnerable, particularly spreading bellflower Campanula patula (EN & BAP) and crested cow-wheat Melampyrum cristatum (VU & BAP), with other declining species include pale St John's-wort Hypericum montanum (NT) and fly orchid Ophrys insectifera (VU & BAP). As well as being negatively affected by a reduction in temporary open space within woodlands, these edge species have probably also been reduced by the linked problems of intensification and abandonment of adjacent open land. Finally, there is a small group of species that appear to be mainly associated with long term or permanent glades, particularly the orchids narrow-leaved helleborine Cephalanthera longifolia (VU & BAP) and red helleborine Cephalanthera rubra (CR & BAP). Many sites for the former in Hampshire and Scotland are

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in woodland that was historically grazed. The edge and glade species may have benefitted from controlled or seasonal grazing within pasture woodlands in the past. The early succession species downy woundwort Stachys germanica (VU) was strongly associated with the mainly compartmentalised pasture woodland of Wychwood Forest and was recorded from the coppices themselves before enclosure (Marren, 1988). Since enclosure in the 1850s, it has only been recorded from scrub wood edges and lanes. It may have been associated with grazing damage in compartmentalised pasture woodland systems, when the separation of grazing and coppicing failed. Cynoglossum germanicum (CR & BAP) was also recorded from Wychwood Forest and may also have occupied this niche.

The many micro-species of whitebeam recorded in the RDB are a specialist type of woodland glade species, being associated with permanent glades formed by base rich rock outcrops within woodlands.

Other species are less strongly associated with very open stages of woodland

development and survive in reduced populations in shady woodland but were much more abundant in regularly coppiced woodland in the past. These include oxlip Primula elatior (NT), Suffolk lungwort Pulmonaria obscura (EN & BAP), lesser butterfly orchid Platanthera bifolia (VU & BAP) and greater butterfly orchid Platanthera chlorantha (NT). The very rare northern whorled Solomon's-seal Polygonatum verticillatum (VU & BAP) is also thought to be suffering from increased shade from ivy in formerly managed ravine woodlands. Shade from invasive shrubs is not mentioned much for vascular plants, compared to bryophytes or lichens. Invasion by the invasive exotic rhododendron will certainly have negatively affected some sites for the hyperoceanic Wilson’s filmy-fern Hymenophyllum wilsonii (NT).

A very different group are parasitic or partly parasitic species found in deeply shaded woods including the orchids white helleborine Cephalanthera damasonium VU & BAP), ghost orchid Epipogium aphyllum (EX) and bird's-nest orchid Neottia nidus-avis (NT), and the unrelated yellow bird's-nest Monotropa hypopitys (EN & BAP). Causes of declines in these species are not clear and the occurrence of some is spasmodic in any one site, This is especially so of the very rare ghost orchid Epipogium aphyllum.

The seven temperate – boreal and boreal species mostly occur in woodlands

that were once, or are still grazed, and several also occur in alternative open habitats. Unbalanced grazing is likely to be a case of losses, with too much grazing causing losses in the past but increasingly too little grazing likely to increase threats from shading and course vegetation. Northern hawk`s-beard Crepis mollis appears a classic example, a species of herb-rich grassland and pasture woodlands in Northern England and Southern Scotland, and now squeezed between intensification and abandonment.

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Small cow-wheat Melampyrum sylvaticum (EN & BAP) is described by Dalrymple (2006) as sensitive to grazing, although it is also described as surviving light grazing. The main threat, however, appears to be the small area of surviving base rich boreal woodland, which could have caused genetic losses to isolated populations.

The pine specialists, twinflower Linnaea borealis and one-flowered

wintergreen Moneses uniflora, in the past showed an ability to colonise pine plantations, but this mature pine plantation habitat has been threatened by clear felling and then replacement by faster growing non-native conifers. The level of protection is lower for such pine plantations than for ancient native pinewoods.

For some species, especially the Near Threatened species, the recorded

declines may represent reduced recording effort, as in the hyperoceanic Wilson’s filmy-fern Hymenophyllum wilsonii (NT), and be less serious than indicated (Preston et al., 2002). In another instance, Italian lords-and-ladies Arum italicum ssp neglectum, the Near Threatened status may relate to recording confusion. The introduced taxon Arum italicum ssp italicum has been more readily recognised in recent years, whereas previously these were mis-recorded as the native subspecies, giving a false impression of a decline (Preston et al., 2002 & French et al., 1999).

General threats recorded for temperate woodland species mainly relate to

past woodland clearance for agriculture and conversion to conifer plantations. For example, one of only three known sites for Suffolk lungwort Pulmonaria obscura was lost to conifer planting (Preston et al., 2002). These are now much reduced threats, especially for ancient woodland, due to national policies promoting the conservation and restoration of ancient woodland within forestry (Forestry Commission, 2005) and in the planning system (ODPM, 2006).

3.1.3 International responsibility An innovation in the latest RDB (Cheffings & Farrell, 2005) was an indication

of the vascular plant species that may be international responsibility species. Like the RDB and BAP lists, open ground species predominate in this list. Beyond the endemic whitebeams, there is also almost no overlap with the RDB and BAP lists, with only the hyperoceanic Wilson’s filmy-fern Hymenophyllum wilsonii (NT), listed as an RDB woodland species which has a British population that is definitely of international importance. No woodland BAP species are listed.

Other than endemic whitebeam microspecies, only 12 woodland vascular

plant species are listed as possibly, potentially or definitely of international responsibility. The five definite species given were all ferns: hay-scented buckler-fern Dryopteris aemula, scaly male-fern Dryopteris affinis, Tunbridge filmy-fern Hymenophyllum tunbrigense, Wilson’s filmy-fern Hymenophyllum wilsonii (NT) and intermediate polypody Polypodium interjectum. Several of these, Dryopteris aemula, Hymenophyllum tunbrigense and Hymenophyllum wilsonii, show strongly oceanic

Comment [TCW4]: Re-worded

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distributions in Europe and are mainly found in temperate hyper-oceanic woodland and temperate oceanic woodland in Britain. The poverty of international responsibility woodland vascular plants in Britain contrasts with the bryophyte and lichen woodland floras.

3.1.4 Influences on the general flora of woodlands The most detailed examination of long term change in British woodlands was

produced by a 2001 resurvey of the vascular plants in 103 plots originally recorded in 1971 (Kirby et al., 2005). This has produced qualitative results that confirm many of the factors discussed above. These include:

Changes to the tree and shrub species

• Oak lost stems in the lowest size classes but gained in the larger ones.

• Young holly showed a marked increase, confirming anecdotal accounts from lichenologists.

• Mean basal area of trees and shrubs increased both for individual plots and across most sites.

• Species richness amongst saplings (25-130cm high) decreased, but small increases in frequency were shown by some shade tolerant species including yew, beech and holly.

• Seedling (< 25 cm high) frequency declined for most species, but holly showed a notable increase.

• Open habitats (rides, glades etc) and some wet habitats (ditches, boggy patches) became less common.

• Grazing signs increased in the lowlands, mainly of deer other than red deer

Ground flora changes

• Overall species richness declined markedly

• ‘Woodland specialists’ were more likely than other species to show decreases in frequency.

• Open habitats declined overall

• Increases in tree basal area were associated with species richness declines; other variables relating to disturbance (1987 storm damage, grazing, open habitats) were associated with increased richness.

• Stress-tolerant species scores declined and were negatively associated with changes in open habitats.

This confirms the ageing of stands with increasing shade and loss of open

habitats, and resulting declines in species diversity, including many woodland specialists. This is combined in the lowlands with increasing deer

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grazing and browsing in areas previously without deer. Interesting features are the failure of oak regeneration and increases in beech and holly regeneration, which reflects the expectations from non-intervention plots (Vera, 2000, & Swift & Howorth, 2006). Canopy disruption and maintaining of open habitats, however, were associated with increased richness.

3.2 Bryophytes 3.2.1 Red Data Book and BAP Species – numbers and distribution The current Red Data Book (Church et al., 2001), unlike the vascular plant

and lichen RDBs, did not assess the whole bryophyte flora, but only those found in 15 or less ten km national grid squares. An assessment of the whole flora would be likely to add more species but it is not clear that this would change the balance between woodland and non-woodland species. It is possible, however, that proportionately more hyper-oceanic woodland species would have been included.

Compared to vascular plants, coverage and data on declines is not as

detailed, simple because there are fewer bryologists recording. Overall, however, knowledge is far more detailed than for lichens or fungi. The bryophyte flora of the Atlantic coast is particularly well studied, for example, Averis (1991) surveyed an extraordinary 448 woods in the Scottish Highlands.

Church et al. (2001) gives useful summaries of the occurrence of threatened

species (excluding Near Threatened species) by habitat. This described ‘Trees and hedgerows’ and ‘Woods’ separately but the basis of this separation is not clearly described. Purely woodland epiphytes such as Zygodon forsteri are described under ‘Trees and hedgerows’. Other than this, the section on woodlands emphasises that, “although woods are the richest and most important habitats for bryophytes in many areas, there are few threatened woodland species”. In particular, the richness of the hyper-oceanic woodlands is emphasised; the bryophyte diversity of these woods is comparable with some tropical forests (Hodgetts, 1993). Here, however, many characteristic species are frequent, occur in more than 15 ten km national grid squares and were not assessed in the RDB.

The analysis for this report found 23 RDB species that could be described as

woodland species on a wide basis (but excluding epiphytes of open habitats and some species only occasionally found in woodlands), out of 208, 11% of the total. Similarly, of the 102 bryophytes listed as priority BAP species, 17 are woodland species, 17% of the total. These are remarkably similar to the proportions for RDB and BAP vascular plants.

The combined total of RDB and BAP woodland species was estimated for this

report as 27, considerably lower than for vascular plants or lichens. Of these, 23 are confined to temperate woodland, three are boreal species and one has been found in both temperate and boreal woods. Within the species of temperate woodlands, compared to vascular plants there are far more hyperoceanic species, with eight species (30%) confined to highly

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oceanic woodlands. These include the mosses Daltonia splachnoides (VU & BAP), found in a few sites in western Scotland, and Sematophyllum demisum (EN), of small rocks in North Welsh woods, and the liverworts Acrobolbus wilsonii (NT & BAP), Radula carringtonii (VU & BAP) and Radula voluta (NT). In contrast to lichens, however, there are no wider woodland southern oceanic species included in the RDB.

Temperate woodland is the main habitat for rare bryophytes, with 14

species (52%) recorded from this habitat type. These include a disparate range of species, including the mosses Zygodon forsteri (EN & BAP) of wound tracks on beech trees in old growth pasture woodlands in southern England, Anomodon longifolius (VU & BAP) on base rich rock in ravines, Atrichum angustatum (EN & BAP) on rides in the Weald, Fissidens exiguus (NT) on wet rocks in streams in woods, Orthotrichum obtusifolium (EN & BAP), a pollution sensitive pioneer epiphyte, and Rhytidiadelphus subpinnatus (EN & BAP) on banks in upland woodlands. Liverworts include Pallavicinia lyellii (VU & BAP), found in a scatter of wet woodlands.

In contrast to lichens, sub-oceanic species are even less significant than for

vascular plants, with one species confined to eastern temperate woodlands, Anomodon attenuatus (EN). This is currently confined to basic rocks in one ravine woodland in Angus. In addition, the pollution sensitive pioneer epiphyte Orthotrichum speciosum (NT) is recorded from both sub-oceanic temperate woodlands and boreal woods in eastern Scotland.

Similar to vascular plants, but unlike lichens, the number of species

confined to boreal woodland is not high, with only three (11%). These are confined to Scotland. They include the striking green shield-moss Buxbaumia viridis, consisting of swollen fruits emerging from fallen logs in old growth boreal woodlands. In addition, the moss Orthotrichum gymnostomum (EX & BAP), which was judged Extinct in the RDB, has been rediscovered in Deeside, as part of the rich epiphytic flora of Aspen, currently being explored in the eastern Highlands (Legg, 2004). Finally, the liverwort Lophozia longiflora is also a dead wood specialist, but has only ever been recorded from one native pinewood in Speyside.

BRYOPHYTES – SPECIES OF CONSERVATION INTEREST

Distribution within climatic regions

Habitat No of bryophytes

% of bryophytes

Temperate 14 52% Temperate, hyper-oceanic 8 30% Temperate, oceanic 0 0% Temperate, sub-oceanic & temperate – boreal, sub-oceanic 2 7% Boreal 3 11%

Non woodland species Six epiphytic species were judged not to be associated with woodland.

These included two species that occurred on riverside trees Cryphaea lamyana (VU) and Myrinia pulvinata (NT) and four species that occurred on

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trees beyond woodland, including two Orthotrichum species (Orthotrichum pumilum CR & BAP & Orthotrichum pallens EN & BAP). The genus Orthotrichum includes many pollution sensitive pioneer twig epiphytes, which have declined drastically in the last 100 years. With cleaner air, they are showing the first signs of a major recovery (BA ref, 2008).

Extinctions Only two definitely woodland species are recorded as extinct - Weissia

mittenii (EX) and Fossombronia crozalsii (EX). Both were woodland ride species. The latter had only ever been recorded from woodland rides but the Weissia was also recorded from arable fields. A further species Neckera pennata has only a single 19th century record from lowland Forfar from non-woodland trees. It is, however, a Vulnerable RDB species in Sweden where it is regarded as a key indicator species of woodland sites of high value (Nitare, 2000). It may have once occurred in sub-oceanic woodland in the east of Britain.

3.2.2 Red Data Book and BAP species – habitats and threats Hyper-oceanic species The resource of bryophyte rich woods in western Scotland, the Lake District

and North Wales is immense but, unlike lichens, has been well explored (Averis, 1991 & Hodgetts, 1997). The number of important sites, however, means that coverage by SSSIs or SACs is hardly comprehensive, with many important sites in Scotland not notified (Hodgetts, 1997 & May, 2002). Conservation of the resource will clearly have to rely on wider forestry and agricultural policy in the core areas of interest. This is reflected in Plantlife’s listing of much of the west coast of Scotland as an Important Plant Area.

The rare hyper-oceanic species are mainly species of rock and less

frequently trees, within ravines, or very humid coastal woods in scattered locations along the west coast. The majority of the RDB and BAP species are found in less accessible sections of the woodlands in which they grow, which insulates them from many threats. This is in contrast to rare lichens, which tend to favour better lit hyper-oceanic woodlands. There is also no strong association with old growth stands (Edwards, 1986) but rich Atlantic bryophyte floras are strongly associated with ancient woodland with a long continuity of woodland cover (Ratcliffe, 1986). The most serious and insidious threat is invasion by the exotic evergreen shrub rhododendron Rhododendron ponticum which can invade even the most inaccessible area. Rothero (2005) emphasised the absolute seriousness of this threat and the general ineffectualness of the response to date. Beech is also a problem (Rothero, 2005), it is locally non-native but is well adapted to the hyper-oceanic climate, and can regenerate more effectively than oak. The shade cast by this species is much deeper than the hazel and ash it displaces in ravines, shading out rich hyper-oceanic communities at several important sites. Conifer plantations in adjacent accessible land have also caused damaging increases in shade. In some sites, upstream pollution could also be a potentially serious threat.

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An emerging threat is ravine running, a mainly organised sport, which

involves taking groups from outdoor centres down ravines as an adventure. This has introduced extreme trampling and disturbance to a habitat that was barely visited in previous decades. This has become a matter of great concern to bryologists.

Inappropriate grazing is often mentioned as a threat, but the less accessible

nature of many of the richest sites suggests that overgrazing is probably not normally a current threat. In contrast, the total removal of grazing to rapidly encourage tree regeneration by fencing can cause potentially serious problems to species growing on smaller rocks. On more fertile sites unrestricted bramble growth can smother boulders up to 2m in height (Rothero, 2005), a considerable threat to slow colonising species.

One RDB moss, Sematophyllum demisum (EN), in particular, is vulnerable to this problem. It is confined to north Wales, where it grows on low slabs and small rocks, which are set in the woodland floor, rather than large ravine rock faces. Here it is very easily overgrown and populations have declined where grazing has been removed from protected sites (Bryan Edwards, pers. com.). In addition, Thomason (1995), suggested that while heavy grazing damages the general Atlantic woodland bryophyte flora, 80% of the internationally important flora was at least partly grazing-dependent in Borrowdale, Lake District.

Some of the very rare Atlantic ravine liverworts are curiously restricted in

distribution, for example, the European endemic Lejeunea mandonii is absent from many apparently suitable sites. This is partly a self-selecting feature; were these species not unaccountably restricted, they would not be in the RDB or the BAP.

Temperate woodland species The 14 species of general temperate woodland include a remarkable seven

species of woodland rides. Some species are largely confined to this habitat, such as Atrichum angustatum (EN & BAP), with most of its records from rides in Wealden woods, plus a few old records from heathlands. It is now very rare, with increased shading as coppicing declines the probable cause of decline. One liverwort Fossombronia crozalsii was only ever recorded from two unsurfaced rides in conifer plantations in north Wiltshire and Berkshire. It has not been refound since 1972, with track surfacing and hence a lack of periodic rutting and also shading from maturing conifer crops the possible causes of the species disappearance. Most species, however, also occur, or occurred, more frequently in other types of disturbed land. Examples include the narrow European endemic, Weissia multicapsularis (EN & BAP), apparently extinct outside of Britain. This survives in Cornwall where it typically grows on banks and track sides on sea cliffs and inland field banks, but has also been recorded from wayside banks, woodland rides, banks in old quarries and fallow fields in the past. This species had a concentration of records from the Weald, where it was likely to have occurred in rides, but has not been seen here since the 19th

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century. Weissia squarrosa (EN & BAP) has been recorded from fields, beside ditches and pools as well as woodland rides. The liverwort Lophozia capitata (VU & BAP) is mainly a species of heathland, occasionally being recorded from rides in woods.

The loss of bryophyte diversity on rides does appear to be a significant

issue. Another example is the complete disappearance of the widespread moss Calliergonella lindbergii from Dorset, where it had previously been recorded sparsely across the county on tracks and woodland rides, but has not been seen since 1977 (Hill & Edwards, 2003). Similarly, the diversity of ride flora of the Sussex Weald also has declined since the 19th century (Rose et al., 1991). The main drivers appear to be surfacing of the most regularly used rides, removing well lit rutted ground, and increased shade on less used unsurfaced rides. Rutting and disturbance along rides in woodland that favours this suite of species is now regarded as bad forestry practice.

The other species are found in several other habitats. Three are found in less oceanic ravine woodlands or on rocks by woodland streams: Anomodon longifolius (VU & BAP), Fissidens exiguus (NT) and Jungermannia leiantha (CR). The latter liverwort is an interesting example of a species lost from many sites in the 19th century, where it is impossible to say why this happened, and hence work out exactly what the threats are.

Other species occupy a diverse range of habitats. Zygodon forsteri (EN &

BAP) is a southern species of wound tracks and root knotholes on veteran beech trees, which is possibly the only old growth dependent species of temperate bryophyte in the RDB or BAP lists. It is now known from three sites, Epping Forest, Burnham Beeches and the New Forest. It has shifting meta-populations with long occupied main colonies on longer lasting wound tracks and more ephemeral occurrences in smaller knothole habitats. It has small vulnerable populations dependent on new well-developed wound tracks developing before existing main colony trees collapse. Like many lichens, it probably needs large areas of old growth woodland to survive. Several previously unknown meta-populations have recently been found in the much larger old growth woodlands of the New Forest, where five separate populations are now known, as opposed to the two known a few decades ago. In contrast, it has declined in the smaller Epping Forest. As well as continuity of old trees, shading by holly may also be a threat, especially in pasture woodlands that are no longer grazed.

Pallavicinia lyellii (VU & BAP) is a puzzlingly dispersed species of the bases

of trees in wet woodland, the sides of tussocks in Molinia mires and wet shaded sandstone rocks. This is a long persistent plant of scattered localities occupying a narrow niche in stable conditions (Turner, 2004). This species has declined in many of its wet woodland sites. The reasons are not clear but Sanderson (2005b) found that the species was responding well to small canopy clearance resulting from holly and rhododendron control in a grazed alder wood at Cadnam Bog in the New Forest. Turner (2003) had

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predicted that this opening up could have been harmful. Increased shading and reductions in light levels and lack of occasional disturbance may be issues in its wet woodland sites. Many former and current sites were on commons and are or were once grazed, although it is unlikely to be favoured by heavy grazing pressures.

Orthotrichum obtusifolium (EN & BAP) is a pollution sensitive pioneer

epiphyte, specialising on elm, threatened by both air pollution and elm disease and surviving recently only in clean air areas in north east Scotland. Several species of Orthotrichum declined drastically in response to sulphur dioxide pollution. Most are not particularly woodland species and some were only recorded on open grown trees. Several may now be recovering with clearer air, but Orthotrichum obtusifolium faces extra problems as an elm specialist.

Finally, Rhytidiadelphus subpinnatus (EN & BAP) is another puzzlingly

dispersed species, this time of acid banks in upland temperate woodlands in Wales and northern England. Many past records were from the north of England from areas where acidifying air pollution has reduced the occurrence of all Rhytidiadelphus species.

Temperate, sub-oceanic and boreal woodland species Temperate, sub-oceanic and boreal species include another rare ravine

species Anomodon attenuatus (EN) and further Orthotrichum species Orthotrichum speciosum (NT) and Orthotrichum gymnostomum (EX & BAP). The latter is a recently rediscovered aspen specialist (Legg, 2004). This habitat is also rich in rare lichens and is discussed further in the lichen section. Finally two boreal species - the moss Buxbaumia viridis (EN & BAP) and the liverwort Lophozia longiflora (DD & BAP) - are species of fallen dead wood and are likely to be old growth dependent species. The former occurs ephemerally on large fallen logs as they decay, is dependent on a continued supply of falling large trees and probably needs large areas of habitat. Little is known about the liverwort, but it has been recorded twice from dead wood in Speyside in native pinewoods.

Rothero (2006) considers that some level of grazing, provided it is not so

great as to cause erosion, is generally good for bryophytes. In boreal woodlands, interesting bryophytes growing on low rocks and rotting logs require some grazing to prevent these habitats being overwhelmed by a coarse herb layer or dwarf shrubs. With reference to the boreal woodlands of the Cairngorms National Park, he expresses concern that the enthusiasm for regenerating the woods may cause the loss of bryophytes of open habitats, including open areas of scree, low crags, small areas of mire and fallen logs. These are richer in bryophytes, including uncommon species, than closed canopy woodland, which is dominated by a few robust species.

3.2.3 International responsibility International responsibility species were not listed in the last bryophyte RDB

(Church et al., 2001), but Britain is among the richest countries for bryophytes in Europe and of significance at a world level (Ratcliffe, 1968,

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Hodgetts, 1993 & Rothero, 2005). Rothero (2005) records that Britain has 65% of the European bryophyte flora and may have an astonishing 5% of the global flora. Clearly there is a need for a systematic listing of international responsibility species as has now been done for vascular plants and lichens.

It is clear from existing work, however, that Britain has a high number of

international responsibility species, and that most are to be found in the highly oceanic Atlantic west. Hyper-oceanic woodlands are not the only habitats of importance in this area; low montane heaths with liverwort mats are also very important and are much more threatened. The Atlantic temperate rain forests of the west coast, however, are among the most important habitats for plant conservation in Britain, although this is poorly expressed in the RDB and BAP lists. They are representative of a rare climatic zone, the European Temperate Rain Forest biome. Other areas of temperate rain forest are all rated as critical for global conservation by WWF but not those in Europe, presumably because our woodlands are semi-natural (Rhind, 2003). There is little evidence, however, to suggest that little disturbed semi-natural hyper-oceanic woods in Europe are any poorer in important species than ‘virgin’ woodlands in other areas of temperate rainforest.

3.3 Lichens 3.3.1 Red Data Book and BAP species – numbers and distribution Data The level of taxonomic and distribution knowledge for lichens is even lower

than for bryophytes. Lichenology is still in an exploratory phase, with new species to Britain and science regularly found. Important sites can still be found, or have only ever had one or two visits. This is especially so in the Scottish Highlands, but even in constantly visited sites, such as the New Forest, new species of conservation interest are regularly found (Sanderson, 2010.). A measure of the lack of knowledge is that there were 272 species in the Data Deficient category in the draft of the new Conservation Assessment used for this report. However, in the 50 years since lichenology was revived in Britain, sufficient knowledge was amassed to allow a comprehensive conservation evaluation of the whole lichen flora (Woods & Coppins, 2003). Since then knowledge has increased exponentially with a large scale database project run by the BLS and a new Conservation Evaluation in draft.

Unlike other fungal groups, however, lichens have the advantage of being perennial and visible all year round, allowing for a more conventional approach to the assessment of conservation interest and site value than is possible for fungi.

Although lichens act like autonomous green plants, they are not plants and

many show a far finer niche specialisation than plants. This leads to large numbers of localised species and much more markedly different assemblages in different woodland biomes. Lichens also tend to occupy

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habitats that are marginal for plants, including bryophytes. One of these habitats are the drier better lit and more stressed epiphytic habitats, so it is not surprising that woodland is particularly significant for lichens.

The draft of a new conservation evaluation of British lichens, which will

replace Woods & Coppins (2003) when finalised, listed 382 species of Conservation Concern or as Near Threatened. Of these, 149 are found in woodlands (39%). Adding epiphytes not normally found in woodlands increases the total of tree associated species to 166 (43%). Similarly, of the 136 lichens listed as priority BAP species, 81 are woodland species, 60% of the total. Adding epiphytes not normally found in woodlands increases the total to 91 tree associated BAP species (67%). The totals and proportions of woodland species are much higher than for vascular plants or bryophytes. In addition, the BAP list concentrates much more on woodland species for lichens than for vascular plants or bryophytes.

Totals The combined total of RDB and BAP woodland species on the draft used was

155. Of these, 109 are largely confined to temperate woodland, 32 are boreal woodland species and 14 are found in both temperate and boreal woods. Boreal woodlands have a far larger number and percentage of rare lichens than mosses or vascular plants. The temperate woodland species are also more strongly differentiated between different climatic zones. As well as 38 (25%) generally distributed species, 35 (23%) are largely confined to hyper-oceanic temperate woodland, 33 (21%), are somewhat more widely distributed, and usually more southern, oceanic species and 17 (11%) are sub-oceanic species mainly confined to the east of Scotland and north east England. The two groups of oceanic species account for 68 species (44%).

Habitat No of

lichens % of total

Temperate & temperate – boreal 38 25% Temperate, hyper-oceanic & temperate – boreal, hyper-oceanic 35 23% Temperate, oceanic & temperate, oceanic (southern) 33 21% Temperate, sub-oceanic & temperate – boreal, sub-oceanic 17 11% Boreal 32 21%

Hyper-oceanic temperate woodland The majority of rare species of hyper-oceanic temperate woodland have

distributions centred on western Scotland. Many are confined to western Scotland in Britain, especially smooth bark specialist species such as Arthonia ilicinella (NT), Arthothelium dictyosporum (NT & BAP), Arthothelium macounii (VU& BAP), Eopyrenula septemseptata (NT), Graphis alboscripta (NT), Pyrenula dermatodes (CR & BAP) and Ramonia azorica (EN). Graphis alboscripta (NT) is an apparent endemic confined to west Scotland, while Ramonia azorica (EN) is otherwise only known from the Azores. There are even rare fungal parasites of hyperoceanic species such as Arthonia cohabitans (VU & BAP), an obligate parasite of the very rare Arthothelium macounii (VU& BAP), and Opegrapha brevis (NT), an obligate parasite of more widespread Thelotrema petractoides. Species of rougher bark on larger trees tend not to be totally confined to western Scotland, but

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Lecanora cinereofusca (VU & BAP), Leptogium hibernicum (NT & BAP) and Polychidium dendriscum (VU& BAP) are not currently known in Britain beyond Scotland. Many of the latter group of species still have occasional or rare occurrences in the Lake District, North Wales and south west England. These include several larger showy species, including Gomphillus calycioides (NT & BAP), Leptogium brebissonii (NT & BAP), Leptogium cochleatum VU & BAP), Pseudocyphellaria intricata NT & BAP), Pseudocyphellaria lacerata VU & BAP) Pseudocyphellaria norvegica (BAP) and Sticta canariensis independent green morph form (VU & BAP). Despite largely remaining widespread in the Highlands, southwards most are now very rare, declining and in some cases extinct. Similarly, whilst some smooth bark specialists, such as Mycomicrothelia atlantica (NT) Pyrenula hibernica (VU & BAP) and Pyrenula microtheca (NT), occur as extreme rarities southwards, they retain larger populations in the Highlands,

A few southern species are also included with this group, including Graphina

pauciloculata (VU & BAP), a partial parasite of the Nationally Scarce lichen Graphina ruiziana. There are also three species occurring on sheltered rock in woodland - Arthonia atlantica (NT & BAP), Parmotrema robustum (CR & BAP) and Porina effilata (CR & BAP). Finally, the severely threatened Bryoria smithii (CR & BAP) has only recently been known from high altitude oakwoods on Dartmoor.

Temperate oceanic woodland The species grouped as temperate oceanic species are less confined to very

heavy rainfall or coastal areas and most are more southern in distribution. Many get as far east as the New Forest and a few to Sussex along the south coast. Species which are widespread in both the north and south or more northern are Heterodermia japonica (NT), Megalospora tuberculosa (NT & BAP), Fuscopannaria sampaiana (NT & BAP), Parmeliella testacea (NT & BAP), Parmotrema arnoldii (NT) and Wadeana minuta (NT & BAP). The southern oceanic species are typically absent from the west Highlands or are rare there and often confined to the sunniest areas. The latter include Agonimia octospora (NT), Arthonia invadens (NT & BAP), Mycoporum lacteum (NT), Micarea pycnidiophora (NT), Porina hibernica (NT & BAP), Porina rosei (NT), Rinodina isidioides (NT & BAP) and Wadeana dendrographa (NT & BAP). Other species are absent from the west Highlands all together and include Arthonia anglica (EN & BAP), Arthonia astroidestera (NT), Blarneya hibernica (NT & BAP), Enterographa sorediata (NT & BAP), Melaspilea lentiginosa (NT & BAP), Parmelinopsis horrescens (NT & BAP), Parmelinopsis minarum (VU & BAP), Phaeographis lyellii (NT & BAP) and Ramonia nigra (CR & BAP). Two extremely southern species are Cryptolechia carneolutea (VU & BAP) and Opegrapha prosodea (NT & BAP), which are confined to the far south of England and Wales.

Temperate woodland The species found in temperate woodland but not showing strong oceanic or

sub-oceanic tendencies are a mixed group. All show large gaps in their distributions centred on central England, representing areas of past severe air pollution. The group includes some little known species, such as

Comment [TCW5]: Did Neil add ‘stage’? By morph he means ‘form’. Suggest change.

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Arthopyrenia atractospora (NT), Chaenothecopsis caespitosa (NT) and Chaenothecopsis savonica (NT), with a few widely scattered records, but also includes more distinctive groups of species. These include rare species that are widely distributed in unpolluted areas of England and Scotland, including Bacidia circumspecta (VU & BAP), Bacidia incompta (VU & BAP), Biatoridium monasteriense (EN & BAP), Pertusaria velata (VU & BAP), Phlyctis agelaea (NT) and Schismatomma graphidioides (VU & BAP). More southern species with distributions including the Welsh Marches and southern England are Caloplaca herbidella (VU & BAP), Caloplaca lucifuga (VU & BAP), Lecanora quercicola (NT & BAP) and Lecanora sublivescens (NT & BAP). A group of very southern species mainly found in southern England but showing no oceanic tendencies in their distribution, includes Collema fragrans (EN & BAP), Enterographa elaborata (CR & BAP), Megalaria laureri (EN & BAP) and Pyrenula nitida (VU & BAP). A final group of Collema species, Collema fasciculare (NT & BAP), Collema nigrescens (NT) and Collema occultatum (NT), are highly pollution sensitive species that were once widespread across Britain but have retreated to the west and north since the early 19th century.

As would be expected, the species classified as species of temperate –

boreal woodlands are mainly northern species in Britain such as Leptogium saturninum (VU & BAP), Biatoridium delitescens (VU), Chaenothecopsis vainioana (NT) and Ptychographa xylographoides (NT). Also included in this group are two species, Caloplaca flavorubescens (EN & BAP) and Gyalecta ulmi (EN & BAP), which were once more frequent in the south on elm, but whose northern populations have survived better, the latter on rocks.

Temperate sub-oceanic woodland The final group of temperate woodland lichen species are confined to sub-

oceanic areas along the east cost, which have maintained clean air and have surviving woodlands. The richest area is in the eastern Highlands from Perthshire eastwards and north to the lowlands and glens around the Moray Firth. Some species also survive sparingly in the eastern Scottish Borders and North East England. The occurrence of some lichens with this sub-oceanic distribution, in the rain shadow area of Welsh Marches, suggests that many would once have extended further into eastern England. The flora is similar to that found in broadleaved woods in southern Scandinavia. Most rare species are small crust forming species but the larger Fuscopannaria ignobilis (VU & BAP) is more charismatic, while the dogtooth Peltigera lepidophora (CR & BAP) is known from rocks in one Angus ravine woodland. Smaller species include Bacidia subincompta (VU & BAP), Buellia violaceofusca (NT & BAP) and the pin heads Calicium adspersum (CR & BAP), Chaenotheca chlorella (NT), Chaenotheca gracilenta (EN & BAP) and Chaenotheca laevigata (EN & BAP). There is an overlap with boreal woodland, with Biatora efflorescens (NT), Catinaria neuschildii (VU), Sclerophora pallida (VU & BAP) and Sclerophora peronella (NT) found on broadleaved trees in both mixed temperate woodland and boreal woodlands.

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Boreal woodlands The large number of rare lichens confined to boreal native pinewoods and

mixed birch woods is a great contrast to the much smaller numbers of rare vascular plants and bryophytes species confined to this habitat. The lichen flora of these woods has only been seriously explored in the last few decades and was almost totally unknown before 1974 (Coppins & Coppins, 2006), but has proved to be rich and significant. Floristic variation within the boreal woodland lichen flora, as in temperate woodlands, is large east to west. Rare species characteristic of rich old boreal woodlands across this climatic gradient are Alectoria sarmentosa ssp. sarmentosa (NT) on pine and birch and Elixia flexella (NT) on pine lignum. Most rare species, however, can be grouped into either western or eastern assemblages. The western group typically occur as far east as the Glen Affric area and central Perthshire, while eastern species are missing from the pine woods in the hyper-oceanic west coast (Coppins & Coppins, 2006). This leads to the very richest woods being found between the extremes, including the Black Wood of Rannoch, Affric, Strathfarrar and Guisachan. Lichens of western and central pine woods are Buellia arnoldii (NT) and Buellia sanguinolenta (NT) on broadleaved trees and Calicium parvum (NT), Melaspilea lentiginosula (NT) and Micarea elachista (EN) on pine. In addition, a few very rare hyper-oceanic lichens occur on broadleaved trees only in the western woods. A striking example is the remarkable hyper-oceanic pine wood at Barrisdale, where rowans support Pyrenula dermatodes (CR & BAP) and Ramonia azorica (EN), two strongly temperate hyper-oceanic species at their northern most occurrences.

The central and eastern element includes many specialist of pine lignum,

including Chaenotheca xyloxena (VU), Chaenothecopsis pusiola (NT), Cladonia botrytes (CR & BAP), Cladonia cenotea (NT), Cyphelium tigillare (NT), Hypocenomyce anthracophila (EN), Pycnora xanthococca (VU) and Xerotrema megalospora (NT). Bryoria furcellata (VU & BAP) occurs on pine bark and lignum and occasionally birch. Few rare species are confined to pine bark in these woods, with Hypogymnia farinacea (NT) an example. This species and Alectoria sarmentosa ssp. sarmentosa (NT) are the only rare boreal woodland specialists with recent records from northern England in the Pennines. Here they are confined to rocks, where they could be relic boreal woodland species (Gilbert, 2000). Very recent exploration of old aspen stands in the eastern Highlands has added a rich assemblage of rare boreal species, centred on Speyside, but also found in Deeside(see Royal Botanic Garden Edinburgh website http://rbg-web2.rbge.org.uk/lichen/). This has resulted in an avalanche of new species to Britain, with several now added to the RDB or listed as BAP species: Arthonia patellulata (DD & BAP), Bacidia igniarii (VU), Bacidia vermifera (EN), Caloplaca ahtii (DD & BAP), Diplotomma pharcidium (DD & BAP) and Lecanora populicola (NT). Also discovered was Candelariella superdistans (DD & BAP), a lichen parasitic on Lecanora populicola (NT). Juniper stands can also support the striking yellow lichen Vulpicida pinastri (NT & BAP).

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Finally, only two rare species appear to have been recorded from pine plantations in eastern Scotland - Lecidea antiloga (VU) and Ochrolechia arborea (NT). The former has also been recorded from native woodland in Speyside and the latter is a recently identified species.

Non woodland epiphytes A total of 16 species of epiphytic lichens are included in either the RDB, at

Near Threatened status or higher, or are BAP species but were not considered to be woodland species. Of these, eight showed general temperate distributions, seven were temperate oceanic species and one was temperate sub-oceanic. All are strongly associated with field trees in cultural landscapes. There will be some overlap with sites rich in rare woodland lichens. This is particularly so where non-woodland epiphytes occur on more open trees in parklands that also include denser and or more sheltered stands of veteran trees. Many of the rare field tree species were strongly associated with old elm trees.

Extinctions Fifteen woodland species are listed as extinct, i.e. not seen for 50 years or

more. A further species, the southern oceanic Pseudocyphellaria aurata (CR & BAP), is extinct in woodland but still occurs in a single coastal grassland in the Isles of Scilly. For micro-lichens, extinction may not be forever, as lichenology is still in an exploration phase. An example is the New Forest endemic Bacidia subturgidula (CR & BAP), a specialist of lignum exposed on standing live old hollies. This species was collected twice in the 19th century but was not seen again until 2003, when it was rediscovered in the New Forest. It is now known from a second site in the New Forest (Sanderson & Cross, 2003; Cross et al., 2006). The lack of oceanic species in this list of extinct species, compared to their abundance in the list of rare species, is a striking feature. The one extinct species of hyper-oceanic woodland, Arthothelium spectabile (Ex) is a small species that might yet turn up. The species assigned to temperate woodland include four species which were in all probability confined to field trees, leaving a couple of dead wood pin head Calicium species that were probably mainly sub-oceanic in their distribution. There are, however, proportionately more species of sub-oceanic temperate and boreal woodland that are likely to be have been woodland species than in the other groups. All this reflects the current extent and importance of oceanic woodlands and greater historic losses and pressure on woodland in the east.

LICHENS – SPECIES OF CONSERVATION INTEREST Distribution within climatic regions

Extinctions Extinct Extant % Extinct Temperate 6 38 16% Temperate, hyper-oceanic 1 35 3% Temperate, oceanic 1 33 3%

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Temperate, sub-oceanic 4 17 24% Boreal 4 32 13% Totals 16 154 10%

3.3.2 Red Data Book and BAP species – habitats and threats General factors – woodland structure and scale In spite of the strong distinctions between woodland lichen floras of

different climatic zones, there are considerable common factors which apply to all habitats. In particular, most of the rare woodland species covered here are old growth dependent to some degree, either being most frequent in old growth woodlands or confined to such woodlands (Coppins & Coppins, 2005 & 2006; Coppins et al., 2002; Rose, 1992 & 1993; Sanderson, 1996 & 2010.). Some lichens are specifically associated with very old trees. For most species, however, the association with old growth woodland is a combination of a requirement for niches best developed in post mature (trees beyond their economic usefulness but not necessarily that old) or ancient trees, slow growth rates requiring habitat stability and poor colonisation ability requiring long times for colonisation of new trees. The resulting combination is best described as continuity. As a result, although stands rich in rare lichens will have very old trees present, the rare lichens are often not found on the largest trees. The presence of very old trees is a measure of stand continuity, rather than necessarily the only habitat of such lichens (Gustafsson et al., 1992). An extreme example of this are undisturbed Atlantic hazel woods; here rare species are confined to old uncoppiced hazel stands, which can be identified by the presence of old or dead hazel stems on the hazel bushes. The rare species, however, are mainly found on younger stems and require a succession of nearby younger stems to survive, which is lost in coppiced hazel stands (Coppins et al., 2002).

Lichens in general tend to have much stronger niche specificity than green

plants and rare old growth dependent species are among the fussier lichens. Niche diversity is greatest in old growth woods with varied structure and composition. Structural variation, especially in patchy woods with a glade and grove type structure, produces old leaning and twisted trees with varied bark water regimes. Uniformly dense woods with predominantly straight trees are much poorer habitats for lichens. In addition large diameter standing dead wood and, to a much lower degree, fallen deadwood can also be a significant habitat, and is strongly associated with old growth woodland. Variations within and between trees and shrubs in bark pH are also very important in producing niche diversity and are best developed in stands with a range of both species and age classes. Above this is the general liking of lichens for light; few lichens survive in heavily shaded conditions. To complicate the issue further, woodland lichens are mainly defined by their requirements for sheltered conditions, with higher humidity found than outside woodlands. Typically, long exposure to strong summer sunshine is avoided. Species more resistant to desiccation are likely to be widespread also on trees growing outside of woods. Across the sharp oceanic climatic gradient in Britain, this can lead to species which are

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confined to very sheltered woodland conditions in the dry and sunny east being much more tolerant of open conditions in the damp and cloudy west.

This requirement for both good, if indirect, illumination and shelter is

critical and means that classic lightly grazed high forest non-intervention stands, even if old growth, are not high quality lichen habitats. Rapid infill of glades by tree regeneration found in such stands produces conditions that are too dark for rich epiphytic lichen floras to survive. Lichen-rich woodlands require some degree of regeneration failure, in addition to well-developed old growth conditions. The primary mechanism for this is localised high browsing pressures maintaining open old growth stands. This type of woodland structure supports notable concentrations of rare and declining lichens from habitats as disparate as New Forest beech – oak – holly stands (Sanderson, 2007a) and Highland native pinewoods (Coppins & Coppins, 2006). Obviously, such regeneration failures will needed to be localised, over time and spatially, or the woodland will eventually be lost. Historically, such habitat has mainly been provided by extensive grazed old growth woodlands on unenclosed grazings - pasture woodland. It could also occur in the larger and more semi-natural deer parks (Rose, 1992). Such habitat must have also occurred in the wild wood, if these lichen assemblages are not totally anthropogenic. The processes postulated by Vera (2000), where grazing and browsing by wild animals partly drove the structure of the wild wood by maintaining temporary glades, which were later infilled, would certain provide this habitat.

Scale of habitat is also important, and some rare lichens can occur at very

low densities, even in apparently suitable habitat. An example is the veteran beech specialist lichen Megalaria laureri (EN & BAP); this is currently known from less than 30 trees in the New Forest, an old growth complex covering 3,000ha and with approximately a quarter of a million post mature and ancient trees (Sanderson, 1999 & 2001b). Even if the real population is four times as abundant as the known trees, this is still a frequency of tree occupancy of about 0.05%. Very large areas of old growth woodland are needed to support some very specialist species. Sanderson (2010.) recorded that 56 RDB species (CR to NT) and 30 BAP species had been recorded from the 3,000ha of old growth woodland in the New Forest between 1967 and 2007. Ellis & Coppins (2007) found that the diversity of woodland specialist micro-lichens on discrete aspen stands in Scotland was positively correlated with the existence of large areas of woodland in the mid 19th century, not current day woodland size. In this case, stand-scale epiphyte assemblies were coupled to the dynamics of the wider woodland ecosystem, but with a significant lag in the response of epiphyte species richness to habitat spatial structure. Even the aspen specialist Arthonia patellulata (DD & BAP), which is not associated with old growth aspen stands, is still associated with unfragmented woodland landscapes (see project account on Royal Botanic Garden Edinburgh website http://rbg-web2.rbge.org.uk/lichen/) .

In summary, rich assemblages of rare lichens, from southern beech woods to

Highland native pinewoods, are strongly associated with large varied

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structured pasture woodlands, preferably with a glade and grove structure, providing areas of sheltered but well illuminated veteran trees (Sanderson & Wolseley, 2001). Also significant are more relic situations, such as in old parks or small areas of retained veteran trees, as on the boundaries of oceanic woodlands in Exmoor (Wolseley & O’Dare, 1989).

Woodland structure – threats Threats include felling of old growth woodlands, not necessarily for

woodland clearance but also as a part of normal woodland management. At first sight, it would seem astonishing that this is a current threat, but existing old growth woodland has no specific protection in Britain (Alexander et al., 2002) and has poor recognition. Old growth is often thought to be a feature of unmanaged foreign ‘virgin woodlands’ and the concept of managed old growth woodland in Britain has not been wide appreciated. The issue is particularly problematic in the uplands, where veteran trees are smaller and less spectacular, and the age of the stands is easily overlooked (Quelch, 2001). Old hazel stands rich in rare lichens have proved particularly vulnerable (Coppins et al., 2002). Conservation coppicing of probably never previously coppiced stands of hazel has been carried out in western Scotland with the best of intentions, but with devastating consequences to internationally rare lichen assemblages.

In the historic past, large scale losses of old growth woodland occurred as

unenclosed woodlands were enclosed in the 18th and 19th century. Conversion to oak plantation was as devastating to lichen diversity as clearance to open land. Many thousands of hectares of such woodland were lost to plantations of native trees in the 19th century and yet more to plantations of exotic conifers in the 20th century. In the former case, however, recovery is possible; significant partial recolonisation by old growth dependent species has been observed in 18th century oak plantations in the New Forest. These were abandoned back to pasture woodland in the 19th century (Sanderson, 1996 & 2010.). Within 200 -300 years, good recovery has occurred in all communities except those of dry bark on veteran oaks and rain track and wound track assemblages of veteran beech. In western Britain, the numerous 19th industrial oak plantations are potential sites for such recolonisation, aided by the ability of some rare leafy species to survive as relic populations on rocks.

Maintaining the quality of old growth woodland is an even more serious

current threat to lichen diversity. This includes the long appreciated threat in parts of the uplands of centuries of high grazing levels, preventing any regeneration and leading to the eventual loss of the woodlands. Lichen diversity declines long before the total loss of trees; pasture woodlands consisting of nothing but savanna like stands lose critical humidity in all but the most sheltered topographies. Loss of woodland area, or tree density, is also likely to induce an extinction debt, even in reduced, but still sheltered and lichen rich stands (Ellis & Coppins, 2007).

A less appreciated but growing threat is the complete removal of grazing

from previously grazed woodlands as an understandable response to

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overgrazing. As many woods rich in lichens were traditionally grazed, and unenclosed woods may have been grazed continuously since trees returned after the last ice age, this is a drastic action. Although removing or drastically reducing grazing pressure will usually allow woodland to regenerate and be saved from any actual or perceived threat, it also has the potential to devastate rich epiphytic lichen floras by increasing shade (Coppins & Coppins, 2005; Sanderson, 1998a and 2010.; Sanderson & Wolseley, 2001). Declines can be rapid on fertile soils, and the expanding canopy of existing shrub layers can be as problematic as new regeneration (Coppins & Coppins, 1998). In less fertile sites, damaging shade can take longer to develop. Increased cover by shade bearing late succession species, both native species such as holly, ivy and regionally beech, and introduced species such as sycamore and regionally beech, are particular problematic with reduced grazing pressure. The toxic exotic evergreen Rhododendron ponticum is a very serious problem in the west. It is not controlled directly by grazing but, in woods managed by stock grazing, the graziers have a considerable incentive to control seedlings, which has preserved many important woods (B. J. Coppins pers. com.). Woods not grazed by stock have been noticeably more vulnerable to rhododendron invasion in some areas.

A further issue is that the total removal of grazing often fails to regenerate

a similar mixed composition of the existing pasture woodland, with dense birch regeneration produced from the New Forest to Scotland. Sanderson (2004) noted that total removal of grazing on New Forest floodplains tended to produce species-poor birch dominated woodland, while secondary pasture woodland developed under continuous grazing pressure, though thorn scrub was mixed and dominated by ash. Bakker et al. (2004) give a detailed description of the regeneration processes involved in an ash rich grazed old growth floodplain woodland in the New Forest. An appreciation of the need for balanced grazing regimes within anciently grazed woodlands, not the precipitous removal of all grazing, is required. Research into appropriate grazing regimes is desperately required. These are likely to involve variations in grazing pressure over time, with periods of maintenance grazing that suppresses much of the regeneration, alternating with periods of lower grazing pressure allowing more regeneration. Fewer deer and sheep and more cattle and ponies may also be beneficial.

General factors – air pollution Many lichens are very sensitive to air pollution, with past sulphur dioxide

pollution especially damaging (Hawksworth & Rose, 1970). Only areas that remained clean through the last two centuries harbour rich epiphytic floras. As well as direct poisoning by sulphur dioxide, milder but still damaging acidification has selectively removed acid sensitive species in high rainfall areas further from pollution centres (Farmer et al., 1992). The result is that large areas of the country have been effectively sterilised. Much of England, from the Thames valley to north east England, has lost almost all slow colonising old growth dependent lichens, as have south east Wales and the central belt of Scotland. This acidifying pollution has now greatly declined and large scale recolonisation by rapid colonising species is

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underway, but these do not include any rare species. Old growth dependent species have been lost from these areas for the foreseeable future. Pristine clean air areas survived in the Scottish Highlands and the far south west of Wales and England. Wide zones of relatively clean air survived along the south coast of England, north Wales and the northern Lake District. Here, some exceptionally sensitive species, such as the attractive leafy Pseudocyphellaria species, have declined and are threatened with extinction. This is resulting in oceanic species such as Fuscopannaria sampaiana (NT & BAP) and Parmeliella testacea (NT& BAP) beginning to assume distributions similar to hyper-oceanic species, as the western Scottish populations become more significant. These species are not yet obviously recovering. The areas of relatively clean air, however, still have sites rich in less extremely sensitive rare lichen species.

The threat from sulphur-based pollution has greatly receded, but nitrogen

pollution is now an increasing threat. As far as lichens are concerned the main threat is from ammonia from agriculture; nitrous oxides are apparently not directly assimilated by lichens (van Herk, 1999). Effects have been demonstrated by nitrous oxides from traffic, but only at the exceptionally high levels found in inner London (Davies et al., 2007). Ammonia from point sources from agriculture has only a short distance effect, but in areas of highly intensive agriculture the sources combine to produce regions with much altered epiphytic floras (van Herk, 1999). Similar effects have been demonstrated from Britain (Wolesey et al., 2006). As far as rare epiphytic lichens are concerned, the main threats are to field tree specialists, but woodland lichens are also threatened in parkland and woodland sites in zones of intensive agriculture.

General factors – elm disease Dutch elm disease has had a devastating effect on a group of specialist

species, which were largely confined to old elm trees (Edwards, 2005). Many, but not all, are wound track specialists. Some, such as Anaptychia ciliaris ssp. ciliaris (VU & BAP) and Caloplaca luteoalba (VU & BAP), were confined to field elm species. Others, including Bacidia incompta (VU & BAP), span the field tree and woodland habitat, while Bacidia circumspecta (VU & BAP) is confined to woodland habitats. The degree of dependence on elm varies, with field tree species such as Anaptychia ciliaris ssp. ciliaris (VU & BAP) and Caloplaca luteoalba (VU & BAP) and field tree occurrences of Bacidia incompta (VU & BAP) confined largely to elm. These species in this habitat are unlikely to survive. In woodlands, most elm specialists have alternative substrates with wound tracks on beech trees and ash or hollow holly, maple, sycamore and ash, but these only support a fraction of the former populations of these lichens and may not represent sustainable populations. A few, such as Bacidia incompta (VU & BAP), populations on wound tracks and hollow trees in the old growth pasture woodlands of the New Forest are still large enough to be likely to be sustainable.

Hyper-oceanic temperate woodland – habitats and& threats The western Scottish stronghold of this habitat has many large lichen-rich

woodlands with a history of pastoral use, which are surviving old growth or

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recovering old growth woodlands. These are one of the most important habitats for lichen diversity in Europe and the temperate northern hemisphere. Coppins & Coppins (2005) describe the habitat in Scotland. The rare species among the distinctive species defining the assemblage are largely confined to two habitats - smooth bark on hazel and sometimes rowan and rarely holly (Graphidion – undescribed hyper-oceanic communities) and base rich mossy bark (Lobarion) on many species of trees, but particularly ash, hazel and elm. Other habitats, as on acid bark (Parmelietum laevigatae) on birch, alder, willow and oak, support characteristic hyper-oceanic lichens, but have fewer rare and threatened species. Coppins & Coppins (2005) point out the lack of distinctiveness of the flora of oak in this area and the greater importance of species such as hazel and ash. As they discuss, this makes the commonly use name ‘Atlantic Oak Woods’ for hyper-oceanic temperate woodlands rather problematic. A better and more accurate name would be ‘Temperate Rainforest’ (Rhind, 2003). This problem has had negative practical consequences in SSSI and SAC notification, where plantations of oak have been preferentially notified over true native woodlands.

The resource of old lichen-rich woods in western Scotland is immense, but is

under explored. It is likely that many woods of international importance have not yet been visited and many others are little known. As a result statutory notification as SSSI or SAC does not reflect the distribution of the interest, nor are consultations for forestry or regeneration works likely to take lichen interest fully into account, if the interest is unknown. Plantlife’s recent listing of the most of the west coast of Scotland as an Important Plant Area may help alleviate this problem.

The flora reappears with a reduced diversity in north Wales and the Lake

District but the hyper-oceanic element here has probably been greatly reduced in historic times by heavy exploitation of hazel by coppicing (Sanderson, 2006a), which was far more intense than in the west Highlands (Gilbert, 1984; Coppins et al., 2002; Smout et al., 2005). In addition, the species of base-rich bark have lost ground here to acidification from acid rain. Acid rain has also damaged lichen floras in the far south west of the west Highlands, but most areas were never affected.

Rhododendron invasion is one of the most serious issues in hyper-oceanic

woodlands. Much is being done to tackle it in many sites, but this needs to be continued and accelerated. Beech here, although well adapted to the climate, is a recent introduction and the local lichen flora appears poorly adapted to its hard bark. In addition it casts a very deep shade which is a significant threat, not only to hazel specialist flora, but the hazel itself. The non-native sycamore and Norway maple can however have rich Lobarion communities, with rare species. These maples can deeply shade ungrazed woods but, unlike the grazing resistant beech, are controlled in pasture woodlands, where they are not a serious lichen conservation problem. All these tree species are European natives whose absence is due to happenstance in post glacial tree dispersal; automatic eradication is

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probably not advisable. The damage to native biodiversity should be critically assessed first.

Regeneration failure was, and is, a major issue in many woods, especially

woods within deer forests. It is interesting to note, however, that many woods within crofting common grazings have regenerated in the presence of grazing without special assistance (Noble, 1997). Regeneration is now being addressed in many woods, but often this is not carried out in a way that shows much respect to the long tradition of sustainable woodland grazing that has formed these woods and benefited their important bryophyte and lichen floras (Rothero, 2005; Coppins & Coppins, 2005). This is emerging as a major threat to the hyper-oceanic flora, an astonishing fact given that much of the grazing exclusion is publicly funded and is meant to be a conservation measure. Until recently, a significant problem appears to have been the split between forestry and agro-environmental grant aid. Denser and better preserved pastoral woodlands were deemed to be woodlands, within which there was limited encouragement to graze and there are specific grants for excluded grazing. Only open degraded pastoral woodlands are included in some Scottish definitions of wood pasture, which define wood pasture as being trees over grassland (Stiven & Hall, 2004) or as stands with less than 20% tree cover (Smout et al., 2005). These were more likely to be included within agro-environmental schemes and with sustainable grazing encouraged. These habitats, however, are much poorer habitats for woodland lichens than denser pastoral woodlands. There is, more recently, increasing acceptance of the positive role of grazing in woodland conservation with initiatives such as the very positive Woodland Grazing Toolkit developed for Scotland (Sumsion & Pollock, 2005).

A significant recent problem within hyper-oceanic woods is an attempt to

revive wood and timber exploitation (Coppins et al., 2002). The richest areas for lichens are long undisturbed woodlands, often well on the way to recovering from past (18th or 19th century) exploitation, or in some cases probably barely exploited at all, but maintained mainly as sheltered grazing (Watson, 1997; Smout et al., 2005). There is no evidence that significant wood or timber exploitation does anything other than depress lichen diversity in these woods (Gilbert, 1984). It is imperative that a balanced approach is adopted, where old growth woodland is given protection and forestry management is directed to more disturbed or new woods.

There has been a great deal of work started to restore native woods

damaged by conifer planting, but this rarely seems to pay much attention to the character of the original woodland. Restoration appears often to be by rote, with former pasture woodlands, planted with conifers, being converted to dense birch stands or oak plantations (Sanderson, 2006b). The potential for restoring dull industrial oak woods originating from intensive 19th century management back to more diverse native woodlands has been raised by lichenologists (R. Woods, pers. com.; Coppins & Coppins, 2005) but appears to have been little considered.

Oceanic temperate woodland – habitats and threats

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This ranges from upland woodlands in England and Wales, locally with a hyper-oceanic element, through to lowland pasture woodlands in clean air areas in the south and west. Both the southern temperate oceanic species and temperate species are significant components of the threatened lichen flora. A notable feature of these southern woods is the increasing importance of oak compared to Scottish hyper-oceanic woodlands as a substrate for rare and threatened lichens. These occur in both mossy base-rich bark communities (Lobarion) and in other communities poorly developed in the wettest areas. The latter include mesic bark on old oak (Pertusarietum amarae) with crust forming species such as Pertusaria velata (VU & BAP), which lose out to competition with mosses in very wet woods. In the drier lowlands there is also a suite of species found on parkland trees and glade edge trees in woodland in this habitat, including Caloplaca lucifuga (VU & BAP), Lecanora quercicola (NT & BAP) and Lecanora sublivescens (NT & BAP). A particularly important community is found on dry bark on ancient oaks (Lecanactidetum premneae) in both woods and parkland. This community requires very long continuity of old oaks (Sanderson, 1996) and is of international importance in its own right. Smooth bark communities (Graphidion – Graphidetum scriptae) are still important but with holly significant as well as hazel, and with southern oceanic species appearing in place of the hyper-oceanic species. Base-rich bark communities are also different, with oak much more significant, especially for small crustose species, which are squeezed out by mosses in very wet areas. Acid bark (Parmelion laevigatae community) still supports some rare species in the west. Towards the east, standing dead wood becomes more significant for old growth biodiversity but rare species are nearly all sub-oceanic specialists. Wound track and rain track species also become important, with a particularly rich beech flora in the New Forest, the only substantial area of old growth beech woodland surviving within a clean air area (Sanderson, 2007a & 2010.).

Old growth stands are much less widespread south of the Scottish Highlands,

reflecting more intensive woodland management in the medieval and early modern period. There is a closer match between sites rich in rare lichens and SSSIs than in the Highlands, but some important sites are not covered. SAC coverage is often poor, due to the problematic translation of European classifications used in the Habitats Directive and the exclusion of ancient parks from the Directive.

Many threats are similar to the hyper-oceanic woods in Scotland, especially

in the uplands. Rhododendron is also a locally serious threat, although less widespread or as rapidly colonising in drier areas. Beech is native to the south east but an invasive non-native to the north west. In native beech areas, clean air old growth stands are an extremely important resource for lichen conservation. Beyond, it is normally not only a poor substrate but its deep shade can be a threat to lichen diversity. This raises complex issues about post glacial spread of slow colonising trees, which are not yet at climatic equilibrium (Peterken, 1996; Svenning & Skov, 2007) and climate change issues (Wesche, 2003). In the south, shade cast by expanding ivy and holly is developing into a serious issue, especially in ungrazed woods.

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This may be due to warmer winters. Even in the well grazed New Forest woods, cutting is required to control holly (Sanderson, 1991 & 1997; Wright & Westerhoff, 2001) and prevent losses of rare epiphytic lichens.

Grazing is also crucial and is especially problematic in Wales, where there

are no deer, so simple stock fencing can easily exclude all grazing. There has also been a lot of encouragement for fencing off woods in agri-environmental schemes here. As a result, undergrazing is now a greater threat to rare woodland lichens than overgrazing in Wales (R. Woods, pers. com.). In the lowlands, outside of the New Forest, few pasture woodlands are now grazed, but restoration schemes are planned for some important sites, as at Savernake Forest (Sanderson, 2007b). Many important sites are undergrazed and deteriorating.

The New Forest, in contrast, has remained grazed, and must be one of few areas of extensive grazing in Britain not to drastically change its mix of grazers and browsers in the last three centuries (Tubbs, 2001). It is still dominated by the coarse grass grazers cattle and ponies, while most upland pasture woods have largely lost dominant cattle grazing and become dominated by the fine grass grazers/browsers deer and sheep. It is not clear to what degree this or climate produces the much greater resilience to continuous grazing shown by the New Forest pasture woodlands, than that shown by upland pasture woodlands in the last few hundred years.

Landscape parklands containing relic pasture woodlands are important in

the clean air areas in the lowlands. An example of an exceptionally important site is Melbury Park in Dorset, which contains a rich lichen flora characteristic of both woodland and field trees. Some deer parks such as Whiddon Park in Dartmoor are still essentially semi-natural pasture woodlands, but most parks are now rather artificial environments, with the trees managed by planting rather than natural processes. Many have been agriculturally improved and have been damaged by nutrient enrichment from fertiliser use, high stocking levels and felling of old trees. Most of the best parks are SSSIs, and any problems of intensive use and lack of tree planting should be dealt with by the condition assessment process. There are however, important non-SSSI sites and these are much more vulnerable.

As the proportion of surviving old growth woodland is lower, there is an

even greater case for planning the restoration of industrial oak plantations to structurally varied old growth woodlands than that given for the western Highlands (Coppins & Coppins, 2005). Large scale conversions of 18th and 19th century oak plantations to old growth pasture woodland are planned in the New Forest to counteract past fragmentation, amounting to several hundred hectares (Forestry Commission, 2008; Sanderson, 2007c). There is immense scope for more of this in areas such as Dartmoor and Exmoor and mid and north Wales, where there are extensive oak plantations associated with relic lichen-rich woodlands.

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Sub-oceanic temperate woodland – habitats and threats Although this assemblage has been lost from polluted areas in eastern

England and Scotland, it is still patchily distributed in eastern clean air areas. The assemblage is best developed in the eastern Highlands and adjacent lowland around the Moray Firth, with some species reappearing in the east Scottish borders, north east England, east Wales and the Welsh Marches. Beyond this, large areas of eastern Scotland, with clean air, have little or no ancient woodland of any sort, let alone old growth woodland. These areas relied on timber imports from Scandinavia and failed to conserve their woodland as a result (Smout et al., 2005). The assemblage is absent from these areas.

Woods deeper into eastern Highland glens grade into boreal woodland and

are more likely to be intact pasture woodlands. Beyond this the lowland woods tend to be more altered by 19th century forestry but, given the rarity of woodlands in this area, old 19th century oak plantations, as at Dinnet oak wood in Aberdeenshire, can still be valuable as lichen refugia. A lichen-rich parkland survives at Drummond Park in Perthshire.

The inland pasture woodlands share the same issues as upland pasture

woodlands in the west, with a need to find ways of introducing sustainable grazing regimes to avoid either over- or undergrazing. Invasion by shade bearing exotics is again a problem, as at in the Lower Findhorn Woods, where the locally exotic beech is an issue. Overall, however, the severe level of historic deforestation beyond some highland glens is the most glaring issue. There is a particular need to identify and protect surviving old growth and recovering mature growth and to expand the habitat. Practically, expansion is mainly an issue of allowing existing young growth near surviving sites of interest to develop into old growth woodland. New plantings could be useful by the late 22nd and the early 23rd centuries, but are not an immediately practical response.

Boreal woodland – habitats and threats The most obvious woodland type in this category is the well-known and

described native pinewoods. These are certainly magnificent habitats and are one of the most significant old growth woodland resources in Britain. They also include some of the largest old growth stands in Britain. The habitat is also immensely important for the diversity of British lichens. Within the pinewoods, the major lichen habitats, in rough order of priority, are: standing or propped up dead wood, associated old broadleaved trees and the bark of live pines (Coppins & Coppins, 2006). The specialist rare and threatened dead wood lichens are mainly associated with well-lit dead wood attached to live trees, or large hulks of dry standing dead trees or propped (on other trees or their own branches) fallen trees. Shaded and damp dead wood is not a rich habitat for rare lichens. A curious exception to this is the small Cladonia botrytis (CR & BAP), which is strongly associated with well-lit, old and high cut stumps (as produced by hand cutting) in large felled areas that have not regenerated rapidly. A rare species associated with cultural features produced by hand felling within native pine woods and old Scots pine plantations, which are not

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immediately regenerated, is something of a challenge to many preconceptions of how these woods should be managed, either for conservation or forestry.

Lichen-rich stands of native pine wood are typically old growth stands with

open canopies and much dead wood, with requirements for high light levels crucial (Coppins & Coppins, 2006). Similar structures are also valued in Scandinavia (Karlson et al., 1995; Nitare, 2000). In Sweden, these are described as ‘fire-influenced coniferous natural woodlands’ and are produced by frequent low intensity fires. Dense and well-regenerated pinewoods were not listed as special habitats (Karlson et al., 1995).

In oceanic Scotland, grazing may have been more significant in producing

this structure than in continental Scandinavia (Fenton, 2004 & 2008), but it is likely that both grazing and fire were involved. The role of grazing in pinewood conservation appears quite controversial. As is clear in the description of the habitat given by Rackham (2006) and in Smout et al. (2005), the native pinewood habitat is the result of millennia of pasture woodland management. Dennis (1998) argues passionately that, without grazing by native animals such as cattle, many components of the pinewood ecosystem will be lost. In contrast, official actions for the pinewood BAP only mention grazing in a negative light.

The pinewood habitat is not under direct threat, as there is now plenty of

effort to ensure the woods survive and all large areas are in SSSIs and SACs. The need now is to ensure that the quality of the habitat is not compromised by these very efforts to conserve it.

In contrast to the well known pine woods, the other types of boreal

woodlands are little known. These are essentially mixed broadleaved boreal woodlands that replace the pinewoods on more base-rich soils and on acid soils beyond the native range of pine. Most are also old growth pasture woodlands, rich in rare and declining lichens. They are birch dominated but calling them birch woods is not terribly helpful, as it fails to distinguish them from secondary scrub woods.

There has been no systematic study published on the lichens of this habitat,

but recent detailed studies on stands of aspen within such woods are revealing them as an important habitat for boreal lichens (Royal Botanic Garden Edinburgh website http://rbg-web2.rbge.org.uk/lichen/). Aspen stands, mostly within birch-dominated pasture woodlands on better soils and often in enclosed farmland, are rich in species new to Britain. Such stands face the usual problems of past overgrazing and potential future undergrazing. The former prevents regeneration; with the latter, stands are too dark and dense to support rich epiphytic floras. Even less explored are unenclosed higher altitude boreal woods on less acid soils (Friday, 1990). These share many specialised species with the pinewoods, including rare and declining species. They appear to be quite widespread in the central Highlands north of Rannoch Moor and in the Monadhliath, where they fill in a large gap in the pinewood distribution. They appear to be survivors of the

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type of woodlands that Davies (2003b) detected from pollen in western Glen Affric. The best-known example is on the Creag Meagaidh National Nature Reserve. Most are now very damaged by long periods of high grazing pressure and are desperately in need of action to save them, as has occurred at Creag Meagaidh.

3.3.3 International responsibility The conservation evaluation (Woods & Coppins, 2003) lists all species

thought to have 10% or more of their European populations in Britain ie. International Responsibility species (IR). The revised draft used for this report includes 180 species judged to be International Responsibility species, of which a quick count suggests that 142 are woodland species (79%). Combining RDB species of Near Threatened or higher threat status with BAP species produces a total of 83 IR species which are rare or threatened, of which 63 are judged to be woodland species (76%). British woodlands support a large number of lichens for which Britain has an international responsibility.

Even more interesting are the results of a breakdown of international

responsibility by woodland types for RDB and BAP species combined. This shows that more than 50% of the species assigned to the temperate oceanic and temperate hyper-oceanic elements are International Responsibility species. The temperate element is intermediate, with 39% IR species and the temperate, sub-oceanic and boreal elements have 12% and 13% IR species respectively. Essentially many oceanic species that are threatened in Britain are even more threatened in Europe, while more continental and boreal species have much larger populations in Scandinavia. The combined temperate oceanic and temperate hyper-oceanic elements together include 67% of all woodland International Responsibility species of conservation interest.

LICHENS – INTERNATIONAL RESPONSIBILITY SPECIES Distribution of those species of conservation interest, which are also

International Responsibility Species

Habitats/RDB & BAP spp IR spp

Percentage of all IR spp

All spp

Percentage IR spp in habitat

Temperate, oceanic 22 35% 33 67% Temperate, hyper-oceanic 20 32% 35 57% Temperate 15 24% 38 39% Temperate, sub-oceanic 2 3% 17 12% Boreal 4 6% 32 13% All 63 155 41%

It should be noted that, although conserving western oceanic woodlands is

clearly an important responsibility, some individual sub-oceanic and boreal old growth dependent species which are rare in Britain are also threatened in Scandinavia (Nitare, 2000). All lichen-rich old growth stands are potentially of international significance.

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3.4 Habitats 3.4.1 BAP habitats Given that Biodiversity Action Plan woodland habitats cover most semi-

natural woodland habitats, most species covered by this report will occur within BAP habitats. Allocating species to individual BAP habitats was not always straightforward, especially for lower plants, but most vascular plants were relatively straightforward to assign. The plethora of woodland plans for individual woodland habitats that cut across the habitats important for lichens in particular was notable. A single ‘temperate rain forest’ in the west of Britain could include habitats termed Upland Mixed Ashwoods, Upland Oakwood, Upland Birch Wood and Wet Woodland. On top of this, the whole wood would very likely be a pasture woodland, virtually all the conservation interest grazing dependent, and therefore potentially covered by the Wood Pasture BAP. In their turn, these habitats will include distantly related habitats in terms of their overall flora, such as species-poor oak plantations and sub-oceanic woodlands. The concentration on canopy dominants simplifies the classification but a more integrated landscape and land use based approach, focused on hot spots, might have in retrospect been more sensible. It is notable that targets have latterly been set for ancient woodland as a whole, rather than by the originally defined individual habitats.

The Wood Pasture and Parkland plan does have more of a landscape and

land use basis and potentially includes the majority of woods of interest for lichens. The extension of this BAP habitat into the uplands was on the face of it sensible biologically. Much upland wood was traditionally grazed and the majority of species of conservation interest (in most animal groups as well as plants) within it are grazing dependent. Whether it has been successfully applied is more questionable. In reality the Wood Pasture plan appears to have been left with the crumbs of degraded open upland woodlands, which are a poor habitat for pasture woodland lichens, while lichen-rich woodlands are left in other plans. The other plans mostly still have to show that the need for sustainable grazing to maintain lichen-rich woodlands has been taken on board.

For vascular plants, Lowland Mixed Deciduous Woodland is a core BAP

habitat for rare plants, followed by Upland Mixed Ashwoods, reflecting the dominance of base-demanding and lowland species. The majority of the Upland Mixed species are also southern and lowland, as the ‘Upland’ Mixed Ashwoods actually includes areas such as the Wye Valley and the Mendips, which are upland only in having steep slopes and rock outcrops. Rodwell & Dring (2001) observe that ’North Western Mixed Ashwood’ would have been a better name. Lowland Beech and Yew Woodlands share many species with both mixed woods mentioned above and also have a few specialist species. Other upland BAP woodlands (Upland Oakwood, Upland Birchwoods and Native Pine Woodlands) have small numbers of northern and boreal species.

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Most of the latter species occur in woods that have traditionally been grazed so are in habitats potentially covered by the Wood Pasture plan. Quite a few lowland species also occur in pasture woodlands. Wet Woodlands are of very limited significance, probably reflecting the fact that many Wet Woodlands are recent woodlands replacing richer open habitats (Sanderson, 2007d).

VASCULAR PLANTS – PRIORITY BAP HABITATS

Distribution of species of conservation interest within BAP habitats

Priority BAP habitat No of species

Percentage of total no of species of conservation interest

Upland Mixed Ashwoods 19 38% Lowland Mixed Deciduous 18 36% Wood Pasture 12 24% Lowland Beech and Yew Woodland 9 18% Upland Oakwoods 6 12% Native Pine Woodlands 5 10% Upland Birchwoods 5 10% Wet Woodland 2 4%

A particularly curious feature is that several characteristic boreal pinewood

species have more populations within mature Scots pine plantations than within in native pinewoods. These are not included within the native pinewoods, which is ironic, as exactly equivalent mature oak plantations tend to dominate actions within the Upland Oakwood BAP.

For bryophytes, attempting to determine exactly which hyper-oceanic

species were found in either or both of Upland Mixed Ashwoods and Upland Oakwood was not easy, but most ravine species appear likely to be primarily species of Upland Mixed Ashwoods. Upland birch woods, which do not yet have an official definition, were taken to be boreal woodland only, although it is possible that acid hyper-oceanic temperate woods without oak will be included, making the allocation of species near impossible. Pasture woodlands with beech dominant are explicitly excluded from the Lowland Beech and Yew Woodland BAP.

Upland Mixed Ashwoods stand out as a core habitat for rare bryophytes.

The habitat includes general temperate and sub-oceanic woodland species as well as many hyperoceanic species. Most other plans have a reasonable representation of rare species, with between 10 and 21%, but Wet Woodland has only one species and Lowland Beech and Yew Woodland none.

BRYOPHYTES – PRIORITY BAP HABITATS Distribution of species of conservation interest within BAP habitats

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Priority BAP habitat No of

species Percentage of total no of species

of conservation interest Upland Mixed Ashwoods 12 43% Pasture Woodland 6 21% Lowland Mixed Deciduous 5 18% Upland Oakwood 5 18% Native Pine 4 14% Upland Birch Woods 3 11% Wet Woodland 1 4% Lowland Beech and Yew Woodland 0

As with bryophytes, partitioning oceanic lichens between Upland Mixed

Ashwoods and Upland Oakwood, or for that matter Wet Woodland, was not easy. As with bryophytes, in Upland Birchwoods only boreal stands were included; hyper-oceanic birchwoods were taken as being Upland Oakwood, if without hazel or Upland Mixed Ashwoods, if they had hazel. In addition, Atlantic hazel woods were also included in the Upland Mixed Ashwoods. Pasture woodlands with beech dominant are explicitly excluded from the Lowland Beech and Yew Woodland BAP.

Published habitat details confirmed the observations of Coppins & Coppins

(2006) that hazel and ash floras are considerably more significant than oak floras in hyper-oceanic areas. Base-rich woods are richer than acidic woods in rare lichens; Upland Mixed Ashwood leads by a long way over other BAP habitats classified by their canopy type. Of these, Upland Oakwood and Native Pinewood are also of great significance, followed by Lowland Mixed Deciduous Woodland and Upland Birchwoods. Neither Wet Woodland nor Lowland Beech and Yew Woodland are of much significance. However, if beech-dominated pasture woodlands such as the New Forest were included within the latter BAP, its importance would rise dramatically to 50 species or 32% of woodland species of conservation interest.

The association of woodland lichens with traditionally grazed woodlands is

exceptionally high, with 92% of woodland species of conservation interest found within pasture woodlands.

LICHENS – PRIORITY BAP HABITATS Distribution of species of conservation interest within BAP habitats

Priority BAP habitat No of

species Percentage of total no of species

of conservation interest Wood pastures 143 92%

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Upland Mixed Ashwood 78 50% Upland Oakwood 44 28% Native Pinewood 44 28% Lowland Mixed Deciduous Woodland 24 15% Upland Birchwoods 21 14% Lowland Beech and Yew Woodland 1 1% Wet Woodland 1 1%

3.4.2 SAC Annex 1 habitats Fully allocating woodland species of conservation interest within SAC Annex

1 habitats proved impossible in the timescale of this project. This was at least partly due to the ill-defined and confused nature of the definitions of some of the SAC woodland habitats in Britain. These tend to be quite short definitions, which are anchored to a definitive phytosociological classification. A major part of the problem is this combination of short generalised definitions with precise, but European, phytosociological vegetation classifications. The latter were not based on the communities found in Britain but on related European vegetation. In contrast, the descriptions of Scandinavian Annex 1 woodlands should be consulted as an example of what should have been done, giving clear but widely encompassing descriptions of ecosystems (European Commission, 2003).

The most striking problem is with the temperate rain forests. These are one

of Europe’s most important habitats but the category intended to include them 91A0 Old sessile oak woods with Ilex and Blechnum in the British Isles is bizarrely confined to acid sessile oak woods. This excludes the base-rich woods with ash and hazel dominant, which are richer in rare species, or acid woods with birch dominant. The reference to holly (Ilex) as a defining feature is odd as this is hardly now a conspicuous component of many hyper-oceanic woodlands in Britain.

In fact, the whole Annex 1 habitat seems to be based on the Blechno-Quercetum described from the generally strongly acidic Killarney oak – holly woods by Braun-Blanquet & Tüxen (1952) (European Commission, 1991), making it a woefully inadequate description of the range of variation of the temperate rain forests of Britain. The practical result of this is that many internationally important sites are not listed as SACs for this Annex 1 habitat as they are not acid enough or lack oak (May, 2002). This is particularly problematic in the west Highlands, as here woods without oak dominance are richer in rare lichens and mosses than oak-dominated woods (Coppins & Coppins, 2006). As a solution to the misdescription of the temperate rain forests biome, JNCC has notified some of the most important ravine woodlands as Annex 1 9180 * Tilio-Acerion forests of slopes, screes and ravines. This is problematic, however, as although southern ravines as in the Wye Valley do represent northern outliers of Tilio-Acerion, with species such as large leaved lime present, the ravine woods of western Scotland are better referred to the Alno-Ulmion (Rodwell, 1991; Rodwell et al., 2000). This is a very different if equally important woodland type. An example of the oddities this produces is the

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Resipole ravine in the Sunart SAC, Ardnamurchan. This is one of the most important epiphytic lichen sites in Europe. The Annex 1 habitat into which such ravines have been shoehorned, the 9180 * Tilio-Acerion forests of slopes, screes and ravines, however, is only listed as a qualifying feature for the SAC, but not as a primary reason for site selection for the SAC. Other less acid temperate rain forests, without large ravines and with lower oak dominance but of the highest importance, such as Ellary or Loch Melfort, Argyll, are not SACs. Extreme, but vitally important types of temperate rain forests, such as Atlantic hazel woods have no European recognition at all, for example the outstanding Atlantic hazel wood at Ballachuan, Seil, Argyll (Copins et al., 2002). Far better would have been to describe the temperate rain forest properly in the first place. Priority status for old growth, or little disturbed, native woodland within the rainforest could also be justified.

Other issues include:

• The narrow definition of the 91C0 * Caledonian forest as only boreal pine woods is a sad contrast to the inclusiveness of the equivalent Scandinavian Annex 1 habitat 9010 * Western Taïga. Boreal mixed birch woods have therefore been excluded from the British boreal woodland Annex 1 habitat, resulting in important birchwoods, with aspen clones rich in rare lichens, being excluded from immediately adjacent pinewood SACs in Speyside.

• 91A0 Old sessile oak woods with Ilex and Blechnum in the British Isles

have been extended by JNCC to include sub-oceanic woods in north eastern Scotland. These woods have few Atlantic characteristics (Rodwell & Dring, 2001), but include a distinctive lichen assemblage similar to that of Scandinavian woods, including many rare species. These woods are a better match for the Scandinavian Annex 1 habitat 9020 * Fennoscandian hemiboreal natural old broad-leaved deciduous forests (Quercus, Tilia, Acer, Fraxinus or Ulmus) rich in epiphytes.

• Pasture woodlands in Scandinavia that cannot be included with other

woodland types are placed in Annex 1 habitat 9070 Fennoscandian wooded pastures. The equally important pasture woodlands and parklands of Britain are not included in Annex 1. As a result, lowland pasture woodlands without beech and parklands in general have no European recognition. These include some of the most important lichen-rich veteran tree sites in Europe, such as Melbury Park in Dorset and Bocconoc Park in Cornwall. Also excluded are rich pasture sites, such as Savernake Forest, which lack native beech.

• Finally, the most remarkable absence is the Atlantic lowland mixed

deciduous woodland, as defined by the abundance of bluebell (Endymio-Carpinetum type of vegetation). As Rodwell & Dring (2001) state, “it is much to be regretted that a separate Endymion-Carpinetum could not be included as an unambiguous category for the distinctive oak –

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hornbeam woodlands with [bluebell] Hyacinthoides that are confined to the north-west lowlands of the Atlantic zone.” They also add, “although [hornbeam] Carpinus has a limited range in the UK, there seems no reason to regard the distribution of this tree, rather than the general extent of mixed broadleaf woodland with Hyacinthoides, as setting the bounds of the Carpinion with us”. For vascular plants, these are the richest woods for rare vascular plants in Britain and bluebell Hyacinthoides non-scripta itself is an International Responsibility species.

The above problems are not just pedantic. Misnotified SACs will be difficult

to defended from planning applications as habitats of European importance if it turns out that the Annex 1 habitat concerned is not actually present.

3.4.3 Relationships to open habitats The biodiversity losses caused by abandonment and loss of grazing on low

productivity land in the lowlands is well appreciated. Within pasture woodlands, the removal of grazing not only causes the loss of grazing-dependent woodland plants and epiphytes, but also losses from associated open communities. This problem may be starting to be significant in the uplands. The retreat of farming in general, and in particular the exclusion of grazing from pasture woodlands or from moorlands intended to become woods by conservationists, may be beginning to causing serious biodiversity losses. Holland et al. (2008) gives a chilling example where a population of up to 60 flowering spikes of the Vulnerable Red Data Book species small white orchid Pseudorchis albida disappeared in five years from a heath from which the grazing had been removed within the Tyndrum Community Woodland, Perthshire. The author has seen several examples of base-rich flushes within open areas in now fenced off Highland pasture woodlands, which would be regarded as SSSI quality in their own right in the lowlands, which are disappearing under rank grass. Such communities have probably remained open and species-rich for millennia and may have been more natural than the woodlands regenerated in their place (Fenton, 2008).

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4.0 CONCLUSIONS 4.1 Vascular plants Woodlands are clearly an important part of Britain’s biodiversity, and there

are particular areas of concern. These mainly relate to wood edge plants, woodland grassland species and early succession plants.

Britain’s richest woodlands for vascular plants, those to the south, are on

average getting darker and suffering from a change in their grazing regime from very little browsing or grazing to uncontrolled deer grazing. The combination of increasing shade and unbalanced grazing is unlikely to promote a diverse flora and is certainly inimical to the main groups of plants under threat.

The answer lies presumably within woodland policy. There is a lot of

pressure not to clear fell or create large openings in woodland. The concept of continuous cover forestry is presented as an environmentally friendly version of forestry and there are landscape objections to large felling blocks. In discussing continuous cover forestry, Mason et al. (1999) define clear felling as the cutting down of all trees on an area of more than 0.25 ha. This would exclude traditional scale coppicing seen in hot spots for rare plants such as the Wye Valley (Peterken, 2007a & 2007b). As an example, the Woodland Trust is recommending continuous cover forestry methods for restoring conifer plantations to native woodland on replanted ancient woodland sites. This is applied even where these were originally coppices or pasture woodlands (The Woodland Trust, 2005). In both situations, the continuous cover approach is of no obvious benefit to the rarer plants associated with the original woodland types, but it seems to be assumed that it must be of benefit (Sanderson, 2006a).

Any presumption against openness in our woods is not likely to benefit

declining vascular plants. Our woodlands are not mini tropical rain forests; being regularly opened up to an extreme degree has been part of our woodland ecosystems for millennia. The biota appears pre-adapted to this and it is remarkable how little of the flora is well adapted to closed canopy forest - the starting point of the theories of Vera (2000).

Forestry policy needs to counteract the pressures, deliberate or

inadvertent, to reduce openness in woodlands. Specific issues are likely to include encouragement for large scale fellings(as coppice or shelter wood regeneration fellings to restore habitat for early succession species), deer control, management of woodland edges to maintain more open edge habitat, interaction with adjacent land use and the management and retention of woodland grasslands.

There is also a serious international anomaly with the non-inclusion of

lowland mixed bluebell woods within the Habitats Directive. Any opportunity to achieve international recognition for the importance of these woods should be pursued.

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In the north and west the diversity of the vascular plant flora is reduced and here issues are dominated by the needs of bryophytes and lichens. Important rare vascular plant populations do occur in woodlands but these share issues with the bryophytes and lichens.

4.2 Bryophytes Again, rare bryophytes are concentrated in open habitats, but the Red Data

Book for bryophytes (Church et al., 2001) was not compiled in the same way as other RDBs, as only geographically restricted species were considered and this may have resulted in the internationally important temperate rain forest flora being under represented. This Atlantic woodland habitat is easily the most important for bryophytes in Britain and Europe. This internationally important habitat deserves a great deal of attention, which can be combined with action associated with lichens. Issues include international recognition of importance - the woods being part of a European cultural landscape appears to have prejudiced international recognition (Rhind, 2003) and this needs challenging. Habitats Directive characterisation of hyper-oceanic woodland is woefully inadequate and fails to cover the range of variation of temperate rain forest and urgently requires re-examination. At a site level, much more characterising of the actual range of positive management regimes benefiting lower plants is required. To date there appears to have been too much disregard of cultural landscapes and the positive role of grazing. This has resulted in too great a readiness to resort to grazing exclusion and non-cultural models of the habitat, which ignore millennia of human involvement. If Fenton (2008) is correct, these non-cultural models may even be ignoring natural models of the functioning of these ecosystems, in which high grazing levels may be a natural function of the oceanic climate. Essentially overgrazing is not the issue - instead it is unbalanced grazing. Too many sheep or deer may be a problem but this is not solved by undergrazing the habitat.

Outside of hyper-oceanic woodland, the bryophyte ride flora appears to be a

significant feature, which is particularly under threat. This group of species is suffering from a decrease in openness in woodlands, similar to the problems faced by woodland grassland vascular plants.

Another group of species showing a serious decline are Orthotrichum

mosses, which are very sensitive to air pollution but are also pioneer species and good colonists. The loss of elm has confounded the threat to some species. These appear to be just starting a countrywide recovery, as would be expected of pollution sensitive pioneer species, with improving air quality. These species require clean air policies to be maintained for this recovery to continue.

There are a few old growth dependent bryophyte species of veteran trees

and large fallen dead wood. These share issues with numerous lichen species.

4.3 Lichens

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This group is different, with woodland the single most important habitat for rare and threatened lichens. Epiphytic lichens on field and wayside trees are a significant issue that Plantlife has concentrated on, but there are far more rare and declining lichen species within woods that outside them. In particular, the oceanic woods, those with hyper-oceanic and southern oceanic lichen assemblages, are of international importance and share issues with the Atlantic bryophyte flora. As with the bryophytes, these include the international recognition of the importance of the habitat. At a European level, this would include a properly delimited Habitats Directive Annex 1 habitat for temperate rain forest. At an international level, there needs to be recognition that the European temperate rain forest biome is a centre of plant and lichen diversity of international significance on a par with other temperate rain forest biomes (Rhind, 2003).

At a site level, much more characterising of the actual range of positive

management regimes benefiting lower plants is required. To date there appears to have been too much disregard of cultural landscapes and the positive role of grazing. In the case of lichens this is even more critical than for bryophytes, as rich epiphytic lichen assemblages are much more old growth dependent and are found in more accessible and better-lit sites. The maintenance of grazing is even more significant for lichens than for bryophytes and the need for balanced grazing must be emphasised. The problems relating to grazing are not best characterised as overgrazing but as imbalanced grazing, with undergrazing an increasing problem.

The majority of rare and threatened woodland lichens are old growth

dependent species. This also applies to less oceanic woodlands, which are less internationally significant but can still be of high importance, where old growth survives in clean air areas. Old growth is still not specifically protected in Britain and there are serious issues with the maintainance of habitat quality within old growth woodlands. This relates to the heart of the Vera debate - rich epiphytic lichen floras are associated with old growth woodland suffering canopy break up without immediate regeneration. This habitat requires a significant grazing impact to emerge. Existing action for some important woodland types, such as boreal native pinewoods, does not appear to be fully taking into account the conditions required for the survival of the majority of the rare species found within them. The role of grazing within old growth woodlands is confused within the BAP process, and some habitats, which include numerous traditionally grazed woodlands with a high biodiversity value, only mention grazing in the plan as a problem. The Wood Pasture and Parkland BAP is potentially making things worse in some areas. It can gives the impression that grazing is only an issue with park-like habitats, while the greatest lichen diversity, including numerous BAP lichen species, is associated with grazed woodlands, not a savanna-like habitats. There is a need to accept that pasture woodlands are those woods that require grazing to maintain their biodiversity importance, irrespective of whether this fits in with conservationists’ preconceptions or forestry policy.

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There is a need for the conservation of old growth dependent epiphytic floras to be pushed up the agenda to ensure they are not being compromised by well meaning efforts to conserve woodlands, as well as by over exploitation. Swedish forestry practice may be a model to follow (Karlson et al., 1995).

4.4 Issues The following are issues which this report suggests require research and

debate: Fragmentation and new woodland

• Fragmentation of open habitats has been far more severe in the lowlands than in woodland. In addition, open habitats were often very extensive in the early modern period but woodland has largely been highly fragmented for millennia. Perhapsrestoration of open habitats from farmland should greatly exceed new woodland creation on such habitats? This is not to argue against all new woodland, just that the priorities should be sorting out management and condition within existing ancient woodlands and expanding grazed open habitats. With increased demands for food production, there is also a need to prioritise the most effective habitat restorations. Open habitats can be restored to high quality habitats much faster than woodland habitats. Open habitat restoration, however, should have room for new pasture woodlands, for example being created out of older recent woodlands within heathland restoration schemes.

• In the uplands, open semi-natural habitat is still very extensive and

there is certainly room for woodland expansion. There appears to have been large scale fragmentation of some woodlands, especially mixed boreal birch woodland on better soils, since the early modern period. Again, this should not detract from sorting out management and condition within existing ancient woodlands. On the other hand, much native woodland restoration appears to be in the form of plantations, often blanket planting at 2000 trees per hectare, with cultivation (mounding). The latter has allowed planting into wet heath and flushes which were probably naturally open habitats (Fenton, 2008). The contrast with real native woodlands, nearly all of which were pasture woodlands, as opposed to 19th oak plantations, is striking. Native woodlands are highly patterned, typically with a glade and grove structure, with open areas mainly on wet ground and the richest grazing. This patterning is fundamental to biodiversity with these woods, with groups as diverse as woodland epiphytes, open ground vascular plants and rare glade and woodland edge butterflies depending on it. It is also probably a natural feature, not an anthropogenic artefact. Serious native woodland restoration in the uplands could be carried out by planting initial groves, leaving large open areas for future expansion and by allowing grazing for extended periods. In reality, planting appears to be driven by grant aid mechanisms designed for commercial softwood plantations, not native woodlands, and with little

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thought given to grazing and grazing dependent rare species. A further issue is the use of the NVC, rather than the actual existing local woodland composition, as a guide to planting. This appears to be ironing out local distinctness and replacing it with an idealised image of what woods are expected to be, rather than what they were.

Woodland management • Within lowland ancient woodland, especially on base-rich soils, there is

clearly a decline in rare specialist species, matched by a decline in the more widespread common species. This appears to be related to largely increasing shade in woodlands. There is a need for research into effective methods of management that maintain diversity within semi-natural woodlands. These will probably include forestry systems that open up woods much more than currently tends to occur, such as large scale coppicing and more extensive shelterwood fellings in high forest. All of these will have increasing deer numbers as a problem. For rare species, there are likely to be those that have very special requirements relating to lost management systems, such as compartmentalised grazed coppice. Edge species and woodland grassland species are especially likely to be associated with lost arts such as controlled stock grazing within intensively managed woods, as opposed to extensive pasture woodland management.

• How should woodlands within intensively farmed landscapes be buffered

against adjacent intensive land use? Will planting or regenerating recent woodlands around existing ancient woodlands help or mitigate against woodland edge specialists? If these require low productivity species-rich habitats, would nutrient stripping and managed grassland on woodland margins be more effective for declining plants and invertebrates?

• Woodlands within the uplands have been part of extensive pastoral

farming systems for millennia. The majority of woodland plant and animal species of conservation interest are grazing dependent and have survived in grazed woods since trees returned after the ice age. Our oceanic woods are likely to have been naturally and strongly influenced by grazing before man’s arrival. Ungrazed intensively managed woodlands are a recent early modern innovation in many parts of the uplands. Unbalanced and inappropriate grazing has been a major problem in the uplands but not just for woodlands; moorlands have also been widely mismanaged. The answer is surely not to fence woods out of extensive grazing systems, but instead to restore balanced grazing to the whole landscape. The flora and fauna of the uplands appears to have thrived until the early modern period within low input farming landscapes. To quote Prof. Chris Smout, St. Andrews (Bullock, 2005): “Why are we fixated on the Atlantic period? Our knowledge of biodiversity depends on the work of 19th and 20th century scientists and we only tend to value what we had left in the 20th century. Wouldn’t it be more sensible to use the last 400 years as the model?”

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• Little-disturbed grazed old growth woodlands are exceptionally rich in

rare species of epiphytic lichens, especially in hyper-oceanic climates. In the these climates, rich bryophyte floras also occur and the lower plant assemblage is of international importance. Such woods are an international responsibility and there should be detailed research into how to conserve these woods and their associated floras. The observational evidence of specialists does not appear to find that many grant aided conservation management activities are beneficial and some, such as total grazing exclusion, are positively damaging.

Written by Neal Sanderson, 2008. The views in this report are those of the author and not necessarily Plantlife

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