Guidelines for the Selection of Biological Heritage Sites
6. Section 1: Habitat Guidelines
6.7 FRESHWATER HABITATS
i) RIVERS AND STREAMS
Ri1 Detailed guidelines are not yet available. Many of Lancashires rivers, especially those in the Landscape Zone North(1), are considered to be of high nature conservation value. Several major rivers are included in the present list on the basis of available knowledge of riverside habitat quality and/or populations of species. Otherwise, because of the limited amount of information on the biological content of the aquatic environment itself, identification of Biological Heritage Sites is limited to:
a) localised river or stream habitats which meet other habitat or species guidelines; or
b) small streams included in large sites identified primarily on other grounds.
Application
As river courses can change appreciably from year to year, boundaries can be difficult to define. Where appropriate they should include all associated shingle beds, earth banks and fringing trees, shrubs and grassy banks, as well as habitats such as pools, ditches and marshes associated with the lines of old watercourses.
In addition, parts of the flood plain may also be included in order to protect the requirements of breeding and overwintering birds.
ii) PONDS
Po1 Standing water bodies less than 2 hectares with a Lancashire Pond Score equal to or greater than 1.5.
Calculating the Lancashire Pond Score:
1) Record the presence of all species of flowering plants and ferns growing within an area defined by the actual or supposed winter high water level of the water body.
2) Sum the scores of species present according to Table 4. Species known to have been deliberately introduced to the site concerned are scored 1. Species not included in Table 4 do not receive a score. This sum gives the Lancashire Plant Conservation Score.
3) Divide the Lancashire Plant Conservation Score by the number of species recorded from Table 4, to determine the Lancashire Plant Conservation Index.
4) Add the appropriate Diversity Factor from Table 5 to the Lancashire Plant Conservation Index to give the Lancashire Pond Score.
Some of the more commonly introduced species have been assigned two scores in Table 4: the higher score should be used only for sites where the species is known or believed to be of native occurrence.
Application
This guideline applies to ponds which are defined as permanent or seasonal bodies of standing water less than 2 hectares, and can be of natural or (usually) man-made origin.
Tests indicate that the guideline can be applied satisfactorily to most types of pond, including brackish and nutrient-poor types, as well as the more usual nutrient-rich (eutrophic) ponds.
Site boundaries may also include adjacent areas of semi-natural terrestrial habitat as well as the water body itself.
Justification
Although natural bodies of standing water are rare in Lancashire, parts of lowland Lancashire are particularly rich in field ponds. Some of these are important for individual plant and animal species, including amphibians. Others, although sometimes in the midst of intensively cultivated agricultural land are refuges for a range of wildlife which add significantly to the biodiversity of such landscapes. This guideline aims to identify the most important of those ponds in this second category.
The Lancashire Pond Score is a measure of the relative nature conservation value of a pond based upon the occurrence and diversity of flowering plants. The methodology is adapted from that developed for the National Pond Survey, as described in Pond Action (1994; 1998). This uses a scored plant list to assess the conservation value of ponds at a national level in terms of a Plant National Conservation Score and a Plant National Conservation Index. The list of plant species in Table 4 has been adapted from a list of plants used for the national survey, omitting all national Red Data Book species, none of which occur, or are likely to occur, in Lancashire. Species scores are also based on those used in the national survey, and have been devised as follows:
| i) Nationally Scarce (16-30 10 x 10km squares in GB) or ii) Provisional Lancashire Red Data List of Vascular Plants(3) (Endangered) |
8 |
| i) Nationally Scarce (31-100 10 x 10km squares in GB) or ii) Provisional Lancashire Red Data List of Vascular Plants(3)) (Vulnerable) |
4 |
| 2 | |
| 1 |
Table 4 contains several species which are not native to Great Britain. These are all given a score of 1, and are included not so much for their intrinsic interest but because they may add structural diversity and contribute microhabitats to the pond environment.
The use of an index, as opposed to a simple measure of species diversity, allows the use of a single system to assess a wide range of a different pond types, some of which are intrinsically species-poor compared to others.
However, the index will tend to be relatively low for ponds which have a high diversity of low-scoring (common) species. For this reason, a diversity factor has been added to the index: this is based on a tangential function of the number of species present, and progressively weights high diversity, thus compensating for the tendency of the index to penalise high diversity (Table 5).
The character of the land surrounding a pond can significantly affect the wildlife value of the pond. Adjacent areas of semi-natural vegetation for example, provide additional niches for amphibians and other species, and may help to mitigate against adverse effects of surrounding activities e.g. fertiliser run-off.
| SCORE | SCIENTIFIC NAME | COMMON NAME |
|---|---|---|
| 1 | Achillea ptarmica | Sneezewort |
| 1 | Acorus calamus | Sweet-flag |
| 1 | Agrostis stolonifera | Creeping Bent |
| 4 | Alisma lanceolatum | Narrow-leaved Water-plantain |
| 1 | Alisma plantago-aquatica | Water-plantain |
| 1 | Alnus glutinosa | Alder |
| 8 | Alopecurus aequalis | Orange Foxtail |
| 1 | Alopecurus geniculatus | Marsh Foxtail |
| 2 | Anagallis tenella | Bog Pimpernel |
| 2 | Andromeda polifolia | Bog-rosemary |
| 1 | Angelica archangelica | Garden Angelica |
| 1 | Angelica sylvestris | Wild Angelica |
| 2 | Apium graveolens | Wild Celery |
| 4 | Apium inundatum | Lesser Marshwort |
| 1 | Apium nodiflorum | Fools Water-cress |
| 1 | Azolla filiculoides | Water Fern |
| 4 | Baldellia ranunculoides | Lesser Water-plantain |
| 1 | Barbarea intermedia | Medium-flowered Winter-cress |
| 1 | Barbarea vulgaris | Winter-cress |
| 2 | Berula erecta | Lesser Water-parsnip |
| 2 | Bidens cernua | Nodding Bur-marigold |
| 2 | Bidens tripartita | Trifid Bur-marigold |
| 8 | Blysmus compressus | Flat-sedge |
| 2 | Butomus umbellatus | Flowering Rush |
| 8 | Calamagrostis canescens | Purple Small-reed |
| 2 | Calamagrostis epigejos | Wood Small-reed |
| 8 | Callitriche brutia | Pedunculate Water-starwort |
| 2 | Callitriche hamulata | Intermediate Water-starwort |
| 2 | Callitriche hermaphroditica | Autumnal Water-starwort |
| 4 | Callitriche obtusangula | Blunt-fruited Water-starwort |
| 2 | Callitriche platycarpa | Various-leaved Water-starwort |
| 1 | Callitriche stagnalis | Common Water-starwort |
| 8 | Callitriche truncata | Short-leaved Water-starwort |
| 1 | Callitriche agg. (only when C. stagnalis not recorded) | Water-starwort |
| 1 | Caltha palustris | Marsh-marigold |
| 1 | Cardamine amara | Large Bitter-cress |
| 1 | Cardamine pratensis | Cuckooflower |
| 4 | Carex acuta | Slender Tufted-sedge |
| 1 | Carex acutiformis | Lesser Pond-sedge |
| 8 | Carex approprinquata | Fibrous Tussock-sedge |
| 8 | Carex aquatilis | Water Sedge |
| 2 | Carex curta | White Sedge |
| 8 | Carex diandra | Lesser Tussock-sedge |
| 1 | Carex disticha | Brown Sedge |
| 1 | Carex echinata | Star Sedge |
| 2 | Carex elata | Tufted Sedge |
| 8 | Carex elongata | Elongated Sedge |
| 1 | Carex flacca | Glaucous Sedge |
| 2 | Carex hostiana | Tawny Sedge |
| 2 | Carex laevigata | Smooth-stalked Sedge |
| 8 | Carex lasiocarpa | Slender Sedge |
| 8 | Carex limosa | Bog-sedge |
| 1 | Carex nigra | Common Sedge |
| 2 | Carex otrubae | False Fox-sedge |
| 1 | Carex panicea | Carnation Sedge |
| 2 | Carex paniculata | Greater Tussock-sedge |
| 2 | Carex pendula | Pendulous Sedge |
| 2 | Carex pseudocyperus | Cyperus Sedge |
| 1 | Carex pulicaris | Flea Sedge |
| 8 | Carex riparia | Great Pond-sedge |
| 1 | Carex rostrata | Bottle Sedge |
| 2 | Carex spicata | Spiked Sedge |
| 4 | Carex vesicaria | Bladder-sedge |
| 2 | Carex viridula ssp. brachyrrhyncha | Long-stalked Yellow-sedge |
| 1 | Carex viridula ssp. oedocarpa | Common Yellow-sedge |
| 8 | Catabrosa aquatica | Whorl-grass |
| 2 | Ceratophyllum demersum | Rigid Hornwort |
| 8 | Ceratophyllum submersum | Soft Hornwort |
| 8 | Cicuta virosa | Cowbane |
| 4 | Cirsium dissectum | Meadow Thistle |
| 1 | Cirsium palustre | Marsh Thistle |
| 8 | Cladium mariscus | Great Fen-sedge |
| 1 | Conium maculatum | Hemlock |
| 1 | Crassula helmsii | New Zealand Stonecrop |
| 1 | Crepis paludosa | Marsh Hawks-beard |
| 1/8 | Cyperus longus | Galingale |
| 1 | Dactylorhiza fuchsii | Common Spotted-orchid |
| 2 | Dactylorhiza incarnata | Early Marsh-orchid |
| 2 | Dactylorhiza praetermissa/purpurella | Southern/Northern Marsh-orchid |
| 1 | Deschampsia cespitosa | Tufted Hair-grass |
| 1 | Drosera rotundifolia | Round-leaved Sundew |
| 1 | Egeria densa | Large-flowered Waterweed |
| 8 | Elatine hexandra | Six-stamened Waterwort |
| 8 | Eleocharis acicularis | Needle Spike-rush |
| 8 | Eleocharis austriaca | Northern Spike-rush |
| 8 | Eleocharis multicaulis | Many-stalked Spike-rush |
| 1 | Eleocharis palustris | Common Spike-rush |
| 4 | Eleocharis quinqueflora | Few-flowered Spike-rush |
| 2 | Eleocharis uniglumis | Slender Spike-rush |
| 1 | Eleocharis sp.(only when E. palustris not recorded) | Spike-rush |
| 8 | Eleogiton fluitans | Floating Club-rush |
| 1 | Elodea callitrichoides | South-American Waterweed |
| 1 | Elodea canadensis | Canadian Waterweed |
| 1 | Elodea nuttallii | Nuttalls Waterweed |
| 1 | Epilobium brunnescens | New Zealand Willowherb |
| 1 | Epilobium ciliatum | American Willowherb |
| 1 | Epilobium hirsutum | Great Willowherb |
| 1 | Epilobium obscurum | Short-fruited Willowherb |
| 1 | Epilobium palustre | Marsh Willowherb |
| 1 | Epilobium parviflorum | Hoary Willowherb |
| 4 | Epilobium tetragonum | Square-stalked Willowherb |
| 4 | Epipactis palustris | Marsh Helleborine |
| 1 | Equisetum fluviatile | Water Horsetail |
| 1 | Equisetum palustre | Marsh Horsetail |
| 2 | Erica tetralix | Cross-leaved Heath |
| 1 | Eriophorum angustifolium | Common Cottongrass |
| 8 | Eriophorum latifolium | Broad-leaved Cottongrass |
| 1 | Eriophorum vaginatum | Hares-tail Cottongrass |
| 1 | Eupatorium cannabinum | Hemp-agrimony |
| 1 | Filipendula ulmaria | Meadowsweet |
| 1/4 | Frangula alnus | Alder Buckthorn |
| 1 | Galium palustre | Common Marsh-bedstraw |
| 1 | Galium uliginosum | Fen Bedstraw |
| 1 | Geum rivale | Water Avens |
| 1 | Glyceria declinata | Small Sweet-grass |
| 1 | Glyceria fluitans | Floating Sweet-grass |
| 1 | Glyceria maxima | Reed Sweet-grass |
| 1 | Glyceria notata | Plicate Sweet-grass |
| 1 | Gnaphalium uliginosum | Marsh Cudweed |
| 8 | Groenlandia densa | Opposite-leaved Pondweed |
| 1 | Hesperis matrionalis | Dames Violet |
| 2 | Hippuris vulgaris | Mares Tail |
| 2 | Hottonia palustris | Water-violet |
| 8 | Hydrocharis morsus-ranae | Frogbit |
| 1 | Hydrocotyle vulgaris | Marsh Pennywort |
| 8 | Hypericum elodes | Marsh St. Johns-wort |
| 1 | Hypericum tetrapterum | Square-stalked St. Johns-wort |
| 1 | Impatiens capensis | Orange Balsam |
| 1 | Impatiens glandulifera | Indian Balsam |
| 4 | Impatiens noli-tangere | Touch-me-not Balsam |
| 1 | Iris pseudacorus | Yellow Iris |
| 1 | Isolepis setacea | Bristle Club-rush |
| 1 | Juncus acutiflorus | Sharp-flowered Rush |
| 1 | Juncus articulatus | Jointed Rush |
| 1 | Juncus bufonius agg. | Toad Rush |
| 1 | Juncus bulbosus | Bulbous Rush |
| 4 | Juncus compressus | Round-fruited Rush |
| 1 | Juncus conglomeratus | Compact Rush |
| 1 | Juncus effusus | Soft-rush |
| 1 | Juncus inflexus | Hard Rush |
| 8 | Juncus subnodulosus | Blunt-flowered Rush |
| 1 | Lagarosiphon major | Curly Waterweed |
| 2 | Lemna gibba | Fat Duckweed |
| 1 | Lemna minor | Common Duckweed |
| 1 | Lemna minuta | Least Duckweed |
| 1 | Lemna trisulca | Ivy-leaved Duckweed |
| 2 | Littorella uniflora | Shoreweed |
| 1 | Lotus pedunculatus | Greater Birds-foot-trefoil |
| 8 | Luronium natans | Floating Water-plantain |
| 1 | Lychnis flos-cuculi | Ragged-Robin |
| 1 | Lycopus europaeus | Gypsywort |
| 1 | Lysimachia nemorum | Yellow Pimpernel |
| 1/2 | Lysimachia nummularia | Creeping-Jenny |
| 1 | Lysimachia vulgaris | Yellow Loosestrife |
| 2 | Lythrum portula | Water Purslane |
| 1 | Lythrum salicaria | Purple-loosestrife |
| 1 | Mentha aquatica | Water Mint |
| 2 | Menyanthes trifoliata | Bogbean |
| 1 | Mimulus spp. or hybrids | Monkeyflower |
| 1 | Molinia caerulea | Purple Moor-grass |
| 1 | Montia fontana | Blinks |
| 1 | Myosotis laxa | Tufted Forget-me-not |
| 1 | Myososis scorpioides | Water Forget-me-not |
| 2 | Myosotis secunda | Creeping Forget-me-not |
| 8 | Myosoton aquaticum | Water Chickweed |
| 4 | Myrica gale | Bog Myrtle |
| 4 | Myriophyllum alterniflorum | Alternate Water-milfoil |
| 1 | Myriophyllum aquaticum | Parrots Feather |
| 1 | Myriophyllum spicatum | Spiked Water-milfoil |
| 8 | Myriophyllum verticillatum | Whorled Water-milfoil |
| 2 | Narthecium ossifragum | Bog Asphodel |
| 1 | Nuphar lutea | Yellow Water-lily |
| 1/2 | Nymphaea alba | White Water-lily |
| 1 | Nymphoides peltata | Fringed Water-lily |
| 4 | Oenanthe aquatica | Fine-leaved Water-dropwort |
| 1 | Oenanthe crocata | Hemlock Water-dropwort |
| 4 | Oenanthe fistulosa | Tubular Water-dropwort |
| 2 | Oenanthe lachenalii | Parsley Water-dropwort |
| 1/2 | Osmunda regalis | Royal Fern |
| 4 | Parnassia palustris | Grass of Parnassus |
| 8 | Pedicularis palustris | Marsh Lousewort |
| 1 | Persicaria amphibia | Amphibious Bistort |
| 1 | Persicaria hydropiper | Water-pepper |
| 1 | Persicaria lapathifolia | Pale Persicaria |
| 1 | Persicaria maculosa | Redshank |
| 8 | Persicaria mitis | Tasteless Water-pepper |
| 8 | Persicaria minor | Small Water-pepper |
| 1 | Petasites hybridus | Butterbur |
| 1 | Phalaris arundinacea | Reed Canary-grass |
| 1 | Phragmites australis | Common Reed |
| 8 | Pilularia globulifera | Pillwort |
| 1 | Pinguicula vulgaris | Common Butterwort |
| 1 | Potentilla erecta | Tormentil |
| 1 | Potentilla palustris | Marsh Cinquefoil |
| 4 | Potamogeton alpinus | Red Pondweed |
| 2 | Potamogeton berchtoldii | Small Pondweed |
| 8 | Potamogeton coloratus | Fen Pondweed |
| 8 | Potamogeton compressus | Grass-wrack Pondweed |
| 2 | Potamogeton crispus | Curled Pondweed |
| 1 | Potamogeton epihydrus | American Pondweed |
| 8 | Potamogeton filiformis | Slender-leaved Pondweed |
| 8 | Potamogeton friesii | Flat-stalked Pondweed |
| 8 | Potamogeton gramineus | Various-leaved Pondweed |
| 8 | Potamogeton lucens | Shining Pondweed |
| 1 | Potamogeton natans | Broad-leaved Pondweed |
| 2 | Potamogeton obtusifolius | Blunt-leaved Pondweed |
| 2 | Potamogeton pectinatus | Fennel Pondweed |
| 2 | Potamogeton perfoliatus | Perfoliate Pondweed |
| 2 | Potamogeton polygonifolius | Bog Pondweed |
| 4 | Potamogeton praelongus | Long-stalked Pondweed |
| 4 | Potamogeton pusillus | Lesser Pondweed |
| 8 | Potamogeton trichoides | Hairlike Pondweed |
| 1 | Pulicaria dysenterica | Common Fleabane |
| 2 | Ranunculus aquatilis sens. Str. | Common Water-crowfoot |
| 4 | Ranunculus baudotii | Brackish Water-crowfoot |
| 8 | Ranunculus circinatus | Fan-leaved Water-crowfoot |
| 1 | Ranunculus ficaria | Lesser Celandine |
| 1 | Ranunculus flammula | Lesser Spearwort |
| 1 | Ranunculus hederaceus | Ivy-leaved Crowfoot |
| 1/4 | Ranunculus lingua | Greater Spearwort |
| 1 | Ranunculus omiophyllus | Round-leaved Crowfoot |
| 4 | Ranunculus peltatus | Pond Water-crowfoot |
| 2 | Ranunculus penicillatus | Stream Water-crowfoot |
| 1 | Ranunculus sceleratus | Celery-leaved Buttercup |
| 2 | Ranunculus trichophyllus | Thread-leaved Water-crowfoot |
| 8 | Ranunculus tripartitus | Three-lobed Crowfoot |
| 1 | Rhinanthus minor | Yellow-rattle |
| 8 | Rhynchospora alba | White Beak-sedge |
| 4 | Rorippa amphibia | Greater Yellow-cress |
| 1 | Rorippa microphylla | Narrow-fruited Water-cress |
| 1 | Rorippa nasturium-aquaticum | Water-cress |
| 2 | Rorippa palustris | Marsh Yellow-cress |
| 2 | Rorippa sylvestris | Creeping Yellow-cress |
| 1 | Rumex conglomeratus | Clustered Dock |
| 2 | Rumex hydrolapathum | Water Dock |
| 8 | Rumex maritimus | Golden Dock |
| 8 | Rumex palustris | Marsh Dock |
| 1 | Sagina procumbens | Procumbent Pearlwort |
| 2 | Sagittaria sagittifolia | Arrowhead |
| 2 | Samolus valerandi | Brookweed |
| 8 | Schoenoplectus lacustris | Common Club-rush |
| 2 | Schoenoplectus tabernaemontani | Grey Club-rush |
| 8 | Schoenus nigricans | Black Bog-rush |
| 1 | Scrophularia auriculata | Water Figwort |
| 2 | Scrophularia umbrosa | Great Figwort |
| 1 | Scutellaria galericulata | Skullcap |
| 1 | Senecio aquaticus | Marsh Ragwort |
| 1 | Senecio fluviatilis | Broad-leaved Ragwort |
| 1 | Solanum dulcamara | Bittersweet |
| 8 | Sparganium angustifolium | Floating Bur-reed |
| 1 | Sparganium emersum | Unbranched Bur-reed |
| 1 | Sparganium erectum | Branched Bur-reed |
| 8 | Sparganium natans | Least Bur-reed |
| 4 | Spirodela polyrhiza | Greater Duckweed |
| 1 | Stachys palustris | Marsh Woundwort |
| 8 | Stellaria palustris | Marsh Stitchwort |
| 1 | Stellaria uliginosa | Bog Stitchwort |
| 1/8 | Stratiotes aloides | Water-soldier |
| 1 | Symphytum officinale/uplandicum | Common/Russian Comfrey |
| 2 | Thalictrum flavum | Common Meadow-rue |
| 8 | Thelypteris palustris | Marsh Fern |
| 2 | Trichophorum cespitosum | Deergrass |
| 1 | Triglochin palustris | Marsh Arrowgrass |
| 2 | Typha angustifolia | Lesser Bulrush |
| 1 | Typha latifolia | Bulrush |
| 8 | Utricularia australis | Bladderwort |
| 8 | Utricularia intermedia | Intermediate Bladderwort |
| 8 | Utricularia minor | Lesser Bladderwort |
| 8 | Utricularia intermedia | Intermediate Bladderwort |
| 8 | Utricularia vulgaris | Greater Bladderwort |
| 1 | Vaccinium oxycoccos | Cranberry |
| 1 | Valeriana dioica | Marsh Valerian |
| 1 | Vallisneria spiralis | Tapegrass |
| 2 | Veronica anagallis-aquatica | Blue Water-speedwell |
| 1 | Veronica beccabunga | Brooklime |
| 2 | Veronica catenata | Pink Water-speedwell |
| 2 | Veronica scutellata | Marsh Speedwell |
| 1 | Viola palustris | Marsh Violet |
| 8 | Wolffia arrhiza | Rootless Duckweed |
| 2 | Zannichellia palustris | Horned Pondweed |
Table 5. Lancashire Pond Score Diversity Factor
(See Guideline Po1)
| Number
of Species |
Diversity Factor |
Number of Species |
Diversity Factor |
Number of Species |
Diversity Factor |
| 5 |
0.058 | 20 |
0.236 | 35 |
0.430 |
| 6 |
0.070 | 21 |
0.249 | 36 |
0.444 |
| 7 |
0.081 | 22 |
0.261 | 37 |
0.458 |
| 8 |
0.093 | 23 |
0.273 | 38 |
0.472 |
| 9 |
0.105 | 24 |
0.286 | 39 |
0.486 |
| 10 |
0.117 | 25 |
0.299 | 40 |
0.500 |
| 11 |
0.128 | 26 |
0.311 | 41 |
0.515 |
| 12 |
0.140 | 27 |
0.324 | 42 |
0.530 |
| 13 |
0.152 | 28 |
0.337 | 43 |
0.545 |
| 14 |
0.164 | 29 |
0.50 | 44 |
0.560 |
| 15 |
0.176 | 30 |
0.363 | 45 |
0.576 |
| 16 |
0.188 | 31 |
0.376 | 46 |
0.591 |
| 17 |
0.200 | 32 |
0.389 | 47 |
0.601 |
| 18 |
0.212 | 33 |
0.403 | 48 |
0.623 |
| 19 |
0.224 | 34 |
0.416 | 49 |
0.639 |
(1) See Appendix 1.
(2) Regionally local species are those which are deemed to be "local"
in the regional context (northern England) by Pond Action.
(3) Lancashire County Council (in prep.)
(4) Scientific and common names are taken from Stace
2nd Edition (1997).