Guidelines for the Selection of Biological Heritage Sites

7. Section 2: Species Guidelines

7.2 NON-VASCULAR PLANTS

Application (all non-vascular plant guidelines)

Non-vascular plants include lichens, mosses and liverworts, and algae. Their distribution in Lancashire is less well-known than that of flowering plants and ferns, and the species lists given below should be regarded as tentative. These lists include species recorded in Lancashire since 1950, those species not recorded since 1977 being shown with an asterisk. Only sites from which relevant records have been made since 1987 should usually be considered for designation as Biological Heritage Sites. However, consideration may be given (except where otherwise stated) to sites where records have been made between 1978 and 1986 where no gross habitat changes are evident that are likely to have affected the species concerned. Records made between 1950 and 1977 are considered to require confirmation and sites which qualify only on the basis of such records should be identified as provisional entries only. Several of the following guidelines are based on those in Guidelines for the selection of biological Sites of Special Scientific Interest: non-vascular plants (Hodgetts 1992), and on information on the national and international status of species supplied by Hodgetts (pers. comm.) and given in Church et al. (1997) and in Ing (1995).

Justification (all non-vascular plant guidelines)

Although often inconspicuous and under-recorded, the non-vascular flora of Britain is one of the richest in Europe. Of particular importance are those lichens, mosses and liverworts which require relatively mild wet conditions which occur in western Britain. Although Lancashires non-vascular plants have suffered from the effects of development, and atmospheric pollution in particular, many species of national as well as local importance remain.

i) LICHENS

Application (all lichen guidelines)

Some lichen species may have very restricted distributions at the local level, being confined, for example, to a single isolated tree in a given locality. In such cases the `site supporting them may be quite small. In other cases, however, there is a reasonable possibility of such a lichen species spreading more widely within a larger area which offers appropriate habitat opportunities e.g. an area of woodland or willow scrub, and this, too, should be reflected in the site boundary adopted. Some lichens grow on man-made stone or metal structures, and consideration may be given to the inclusion of gravestones, quarries etc. Scientific names of lichens follow Purvis et al. (1992); detailed species information was supplied by Seaward (pers. comm.) and Gosling (pers. comm.).

---

Li1(a) Any site which supports a population of a lichen species listed in Schedule 8 of the Wildlife and Countryside Act 1981 (as amended) or in Red Data Books of Britain and Ireland: Lichens. Volume 1: Britain⁽¹⁾.

Application

All sites for lichens in the above categories should be included, although no Schedule 8 species have so far been recorded from Lancashire. Pending publication of the Red Data Book, a list of nationally rare species has been supplied by Hodgetts (pers. comm.). A tentative list of species included in Church et al. (1997) so far recorded in Lancashire includes:

Lecidea promixta
Leptogium diffractum
Leptogium massiliense

Justification

The species in the above categories are either threatened or rare in Western Europe or Britain and for which there is either an international or national responsibility for their conservation.

---

Li1(b) Any site which supports a population of a lichen species threatened in Europe which is also 'nationally scarce'.

Application

All sites for lichens in the above category should be included. All 'nationally scarce' lichen species are listed by Hodgetts (pers. comm.). Species which are threatened in Europe have also been listed by Hodgetts (pers. comm.), based on Serusiaux (1989). There are no recent records from Lancashire for species in this category.

Justification

Britain is particularly rich in lichens because of its geographical position in the path of the North Atlantic Drift. Many lichen species which are rare in a European context are not nationally rare in Britain (see Guideline Li1(a)). Some of them are however 'nationally scarce', being recorded in only 16 to 100 10km squares (inclusive) in Britain. There is an international responsibility to conserve populations of these species.

---

Li1(c)Any site which supports a population of a lichen species threatened in Europe, but neither in Red Data Books of Britain and Ireland: Lichens. Volume 1: Britain⁽¹⁾ nor 'nationally scarce', where such populations contribute significantly to the distribution pattern, or the total population size, of that species in Lancashire.

Application

Sites which support lichens in the above category may be considered for inclusion where they significantly extend the geographical range of the species in Lancashire or support a significant proportion of the estimated total County population. All 'nationally scarce' lichen species (see Li1(b)) are listed by Hodgetts (pers. comm.). Species which are threatened in Europe have also been listed by Church et al. (1997), based on Serusiaux (1989). Species so far recorded in Lancashire which are threatened in Europe but not listed in the Red Data Book or nationally scarce include:

Cladonia luteoalba
Lobaria virens

Justification

Britain has an international responsibility to conserve the most important populations of these species.
See also Guideline Li1(b).

---

Li2 Any site which supports a population of a 'nationally scarce' lichen species not covered by guideline Li1(b).

Application

All sites for lichen species in this category (as listed by Hodgetts (pers. comm.)) should be included. A tentative list of relevant species so far recorded in Lancashire includes:

Justification

'Nationally scarce' species occur in 16 to 100 10km squares (inclusive) in Britain; there is a national responsibility for their conservation.

---

Li3 Any site which supports a population of a lichen species recorded from 3 or fewer localities in Lancashire.

Application

All sites for lichens in the above category which are not included under Guidelines Li1 or Li2 should be considered. The following list of species so far recorded at 3 or fewer localities in Lancashire should be regarded as a guide only since it may include species which are under-recorded:

Justification

This list includes some species which may be common elsewhere in Britain, but are rare in Lancashire mainly because of past industrial pollution although it is likely that a number are under-recorded. Small relict populations of such species survive only in those parts of the County which were remote from centres of pollution. Subject to further localities for these species being found, they may provisionally be regarded as 'endangered' in a County context. Other species which qualify for inclusion in this list will come to light with further surveys.

---

Li4 Any site which supports a significant proportion of the Lancashire population, or contributes significantly to the range in Lancashire, of a lichen species which is recorded from more than 3 localities in the County, but which could be at risk because of very small populations, recent rapid decline, or habitat loss or change.

Application

Sites for lichen species in the above categories which are not included under Guidelines Li1 or Li2 may be considered for inclusion where they significantly extend the geographical range of the species in Lancashire, or support a significant proportion of the known total County population of that species. It is considered that the systematic recent recording of lichens in Lancashire is insufficiently advanced to allow any reasonably complete listing of species to be produced for this guideline.

Justification

Species included here, whilst not in immediate danger of extinction in the County may, nevertheless, be at risk and could fall into the 'endangered' category (see Li3: Justification) without adequate preventative measures.

---

Li5 Any site with a New Index of Ecological Continuity equal to or greater than 13.

Application

The New Index of Ecological Continuity (NIEC) should be used in ancient woodland and parkland sites. It is calculated by summing the number of lichen species present, from a total of 70 eligible species listed in Hodgetts (1992). For guidance purposes, the eligible species which have been recorded in Lancashire include:

This list may include species for which there are no recent records.

Justification

A number of Indices of Ecological Continuity (Rose, 1992) have been developed to identify ancient woodland and parkland sites which are potentially rich in epiphytic lichens by the use of a list of indicator species, the presence of which is believed to signify ecological continuity in the past. The New Index of Ecological Continuity is applicable in Lancashire. The qualifying score of 13 is calculated on the basis of the number of qualifying species which occur in Lancashire.

---

Li6 Any site in Landscape Zones West and South⁽²⁾ which supports six of the following lichen species:

Dimerella pineti

Lecidella elaeochroma

Parmelia caperata
Parmelia perlata
Parmelia revoluta
Physcia aipolia

Ramalina farinacea
Rinodina exigua

Usnea subfloridana

Application

All sites with six or more of the species listed above recorded since 1987 should be included.

Justification

Lancashires lichen flora has been greatly impoverished due, in large part, to past atmospheric pollution. In particular, most lichens are very sensitive to elevated sulphur dioxide levels. The species listed above are moderately pollution-sensitive; their recolonization of sites close to urban areas is proceeding as atmospheric pollution loads decline. It can take many years for lichen recolonization to take place and it is important to protect the best examples of recolonizing sites to act as nuclei for their continued spread to other areas of the County.

---

ii) MOSSES AND LIVERWORTS (BRYOPHYTES)

Application (all bryophyte guidelines)

Rare Bryophytes in Lancashire(Wigginton 1990) lists those records of rare species made since 1950. The later publication Mosses and Liverworts of North Lancashire (Wigginton 1995) builds upon the earlier publication with survey data spanning the period 1978-1995.

Scientific names used for bryophytes follow Corley et al. (1981) with updates by Corley and Crundwell (1991), together with recent modifications, for mosses; Grolle (1983), with recent modifications, for liverworts.

Justification (all bryophyte guidelines)

Recording of bryophytes in Lancashire since 1978 has concentrated in that part of the County likely to support the large majority of the scarcer species. The species lists for these guidelines, whilst not definitive, should include most of the relevant species.

Br1(a) Any site which supports a population of a bryophyte species listed in Schedule 8 of the Wildlife and Countryside Act 1981 (as amended) or in the Red Data Books of Britain and Ireland: Mosses and Liverworts⁽³⁾.

Application

All sites for bryophytes in the above categories should be included, although no Schedule 8 species have so far been recorded from Lancashire. Pending publication of the Red Data Book, a list of nationally rare species has been supplied by Hodgetts (pers. comm.). A provisional list of species recorded in Lancashire since 1950 includes:

MOSSES

* Ephemerum sessile
Habrodon perpusillus
Myrinia pulvinata
* Physcomitrium sphaericum
Rhytidiadelphus subpinnatus
* Weissia rostellata

LIVERWORTS

no species recorded

Justification

The species in the above categories are either threatened or rare in Western Europe or Britain and for which there is either an international or national responsibility for their conservation. Nationally rare species are generally those which are recorded from 15 or fewer 10km squares in Britain.

---

Br1(b) Any site which supports a population of a bryophyte species threatened in Europe which is also 'nationally scarce'.

Application

All sites for bryophytes in the above category should be included. All 'nationally scarce' bryophyte species are listed by Hodgetts (pers. comm.). Species which are threatened in Europe have also been listed by Hodgetts (pers. comm.), based on Schumacker (1990). A provisional list of species recorded in Lancashire since 1950 includes:

MOSSES

Bryum riparium

Campylium elodes

LIVERWORT

* Haplomitrium hookeri

Justification

Britain is particularly rich in bryophytes because of its geographical position in the path of the North Atlantic Drift. Many bryophyte species which are rare in a European context are not nationally rare in Britain (see Guideline Br1(a)). Some of them are, however, 'nationally scarce', being recorded only in 16 to 100 10km squares (inclusive) in Britain. Britain therefore has an international responsibility to conserve populations of these species.

---

Br2 Any site which supports a population of a 'nationally scarce' bryophyte species not covered by guideline Br1(b).

Application

All sites for bryophytes in this category (as listed in Hodgetts 1992) should be included. Those species recorded in Lancashire since 1950 include:

MOSSES

LIVERWORTS

Justification

'Nationally scarce' species occur in 16 to 100 10km squares (inclusive) in Britain; there is a national responsibility for their conservation.

---

Br3 Any site which supports a population of a bryophyte species which is recorded from 3 or fewer localities in Lancashire.

Application

All sites for bryophytes in the above category which are not included under Guidelines Br1 or Br2 should be considered. The following list of species recorded since 1950 should be regarded as a guide only since it may include species which are under-recorded:

MOSSES

LIVERWORTS

Justification

This list includes some species which may be common elsewhere in Britain, but are rare in Lancashire, largely because of past atmospheric pollution or loss of habitat. Small relict populations of such species survive mainly in the remoter parts of the County. Subject to further localities for these species being discovered, they may provisionally be regarded as 'endangered' in a County context.

---

Br4 Any site which supports a significant proportion of the Lancashire population, or contributes significantly to the range in Lancashire, of a bryophyte species which is recorded from more than 3 localities in the County, but which could be at risk because of very small populations, recent rapid decline, or habitat loss or change.

Application

Sites for bryophyte species in the above categories (not included under Guidelines Br1 or Br2) may be considered for inclusion where they significantly extend the geographical range of the species in Lancashire, or support a significant proportion of the known total County population of that species.

The following list of species so far recorded at 4 to 10 localities in Lancashire should be regarded as a guide since it may include species which are under-recorded:

MOSSES

LIVERWORTS

Justification

Species included here, whilst not in immediate danger of extinction in the County may, nevertheless, be at risk and could fall into the 'endangered' category (see Br3: Justification) without adequate preventative measures.

---

Br5 Any site supporting an assemblage of 5 or more species of Atlantic bryophytes.

Application

Any site with an assemblage of five or more Atlantic bryophytes, as defined by Ratcliffe (1968) and modified by Averis (1991), should be considered. For guidance purposes, the eligible species which have been recorded in Lancashire include the following.

MOSSES

LIVERWORTS

Justification

Communities of Atlantic bryophytes are of international importance and are particularly well represented in western Britain.

---

iii) STONEWORTS AND OTHER ALGAE

Application (all algae guidelines)

The following guidelines apply only to stoneworts (charophytes), flowerless aquatic plants of uncertain taxonomic affinities probably distantly related to green algae. Only sites from which relevant species records have been made since 1987 should be considered.

Justification (all algae guidelines)

Although generally little-known and under-recorded, stoneworts are conspicuous aquatic plants, characteristic of a range of relatively unpolluted lowland waters, especially large ponds, pools and canals. Insufficient data is presently to hand on the distribution of other algae (most of which are microscopic) to include guidelines based upon them.

---

St1 Any site which supports a population of a stonewort species included in Red Data Books of Britain and Ireland: Stoneworts.⁽⁴⁾

Application

Those national Red Data Book species which occur or may occur in Lancashire include:

Tolypella prolifera

Justification

These are nationally rare species which have not been recorded recently from many of their former localities in Britain. The conservation of these species and their habitats is a national responsibility.

---

St2 Any site which supports a population of a 'nationally scarce' stonewort species, as listed in Guidelines for the selection of Sites of Special Scientific Interest: non-vascular plants.⁽⁵⁾

Application

Those 'nationally scarce' stonewort species which occur or may occur in Lancashire include:

Chara aspera
Chara pendunculata

Tolypella glomerata

Justification

Although widespread in Britain, these are species which occur in more than 16 but less than 100 10km squares nationally. They have not been recorded recently from most of their former localities in Britain.

---

St3 Any site supporting a population of a stonewort species which is recorded from 3 or fewer localities in Lancashire.

Application

The species to which the guideline may apply include:

Chara globularis

Nitella flexilis

These species are likely to be under-recorded in Lancashire and further survey may reveal that sites which support them should be treated under Guideline St4.

Justification

Although these are species which are of frequent occurrence in some parts of Britain, they are rare in much of lowland England and in Lancashire. Subject to further localities for these species being discovered they may provisionally be regarded as 'endangered' in a County context.

---

St4 Any site which supports a significant proportion of the total Lancashire population, or contributes significantly to the range in Lancashire, of a stonewort species which occurs in more than 3 localities in the County, but which may be at risk because of small populations, recent rapid decline or habitat loss or change.

Application

Sites for stonewort species in the above categories which are not included under Guidelines St1 or St2 may be considered for inclusion where they significantly extend the geographical range of the species in Lancashire, or support a significant proportion of the known total County population of that species. It is considered that the systematic recent recording of stoneworts in Lancashire is insufficiently advanced to allow any reasonably complete listing of species to be produced for this guideline. See also St3 Application.

Justification

Species included here, whilst not in immediate danger of extinction in the County may, nevertheless, be at risk and could fall into the 'endangered' category without adequate preventative measures. See also St3 Justification.

---

* Last recorded 1950-1977.
(1) Church et al (1997).
(2) See Appendix 1.
(3) Stewart and Church (in prep).
(4) Stewart and Church (1993).
(5) Hodgetts (1992).