Provisional revision of the MG4 Alopecurus pratensis - Sanguisorba officinalis community Hilary Wallace and Mike Prosser

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1 Provisional revision of the MG4 Alopecurus pratensis - Sanguisorba officinalis community Hilary Wallace and Mike Prosser Ecological Surveys (Bangor) and Floodplain Meadows Partnership (Open University)

2 BACKGROUND The mesotrophic grassland communities of the NVC are based on very small sample numbers MG4 = 22 quadrats MG8 = 15 quadrats Many surveyors were experiencing difficulties in fitting their field data to the described units Considerably more data have been collected on floodplain meadows than were available at the time of publication of the NVC in In particular work of Gowing et al where 3910 vegetation quadrats were linked to soil water levels through hydrological models. This work demonstrated substantial floristic variation within many of the NVC communities linked to soil moisture regime.

3 Since that time, particular research projects, such as the Defra-funded study of the hydrological control of biodiversity in flood plain meadows (Gowing et al. 2002), have generated further substantial amounts of new data and a revision of the mesotrophic grasslands within both Lowland Meadows and Coastal & Floodplain Grazing Marsh is pressing. (Rodwell et al. 2007). The FMP steering group requested that this work be undertaken in two stages a revision of the MG4 community a revision of the damper communities encountered on floodplains

4 SOURCES OF DATA FOR THE MG4 REVISION Source No. sites No. quadrats Gowing et al Other OU monitoring programmes NVC mapping exercises Map of all sites used in analysis

5 DATA ANALYSIS Twinspan analysis of 4746 quadrats Five cut levels (0, 1, 2, 5, and 33) No downweighting of rare species Six divisions giving 64 endgroups Endgroup amalgamation using Czekanowski co-efficient of similarity

6 RESULTS 11 clusters resulted from the progressive amalgamation of the 64 endgroups Closest NVC community MG6 Lolium perenne - Cynosurus cristatus grassland 1 MG4 Alopecurus pratensis-sanguisorba officinalis grassland MG8 Caltha palustris-cynosurus cristatus grassland 3 MG4/8 Intermediate between MG4 and MG8 1 MG7C Cx-Ag-Sn Lolium perenne-alopecurus pratensis- Festuca pratensis grassland. Filipendula variant of Gowing et al Carex spp-agrostis stolonifera grassland of Cox and Leach 1995 Number of clusters Four clusters, comprising 2503 quadrats, were allocated to the MG4 community. The remainder have been incorporated into the analysis of damper floodplain meadow communities

7 PROPOSED SUBCOMMUNITIES OF MG4 Subcommunity Number of samples Mean species/quadrat Dactylis glomerata (9 41) Typical (8-37) Holcus lanatus (6-31) Agrostis stolonifera (6 26)

8 Dactylis glomerata subcommunity Most species rich subcommunity (average 25 spp m -2 ) Largest stands found at North Meadow and Clattinger Farm (Wiltshire) Yarnton Mead and Grafton Lock (Oxford), Portholme (Cambs)

9 Dactylis subcommunity DIAGNOSTIC SPECIES: Dactylis glomerata Trisetum flavescens Rhinanthus minor Leucanthemum vulgare Arrhenatherum elatius Ranunculus bulbosus Heracleum sphondylium Briza media Leontodon hispidus Yarnton Mead (Oxford)

10 Typical subcommunity Not as rich as the Dactylis unit (average 22 spp m -2 ) Widespread especially at North Meadow and Clattinger Farm (Wiltshire), the Oxford Meads, Derwent Ings, Portholme, Mottey Meadows, Upton Ham.

11 Typical subcommunity DIAGNOSTIC SPECIES None specific to the unit. Good representation of community constants and also a suite of species common to the typical and Dactylis subcommunities including: Trifolium pratense Lolium perenne Cynosurus cristatus Taraxacum officinale Centaurea nigra Plantago lanceolata North Meadow, Cricklade

12 Holcus lanatus subcommunity Lugg Meadows Herefordshire

13 Holcus subcommunity Extensive stands on the River Severn at Upton Ham, Ashleworth Ham, Lugg meadows (Herefordshire), Pixey Mead (Oxon) DIAGNOSTIC SPECIES Species diagnostic of the Dactylis and Typical unit generally scarce or absent Lacks any strong preferential species Grass-dominated vegetation with high frequency and cover of: Alopecurus pratensis Poa trivialis Agrostis stolonifera Upton Ham

14 Agrostis stolonifera subcommunity East Cottingwith, Yorks

15 Agrostis stolonifera subcommunity Wheldrake Ings Derwent Ings Acaster South Ings Clifton Ings (Yorkshire) North Meadow Pixey Mead Achurch Meadow DIAGNOSTIC SPECIES Lacks Holcus lanatus and has Low frequency of many community constants, notably Anthoxanthum odoratum and Ranunculus acris. Grass-dominated and shares with the Holcus unit high frequency and cover of: Alopecurus pratensis Poa trivialis Agrostis stolonifera Preferential species: Filipendula ulmaria Cardamine pratensis Carex acuta Polygonum amphibium Carex disticha Achillea ptarmica

16 SUMMARY OF THE FIELD DIFFERENTIATION OF THE SUBCOMMUNITIES Dactylis Typical Holcus Agrostis (a) plus (b) Trifolium pratensis Cynosurus cristatus Centaurea nigra Plantago lanceolata Prunella vulgaris Cerastium fontanum Bromus racemosus Fritillaria meleagris a b c d (a) Diagnostics Dactylis glomerata Trisetum flavescens Leucanthemum Arrhenatherum Ranunculus bulbosus Heracleum Briza media

17 Dactylis Typical Holcus Agrostis a b c d (a) Diagnostics Dactylis glomerata Trisetum flavescens Leucanthemum Arrhenatherum Ranunculus bulbosus Heracleum Briza media (c ) and (d) Alopecurus pratensis Oenanthe silaifolia Phalaris Elytrigia repens (d) Diagnostics Agrostis stolonifera Cardamine pratensis Carex acuta Carex disticha Achillea ptarmica Myosotis laxa

18 ENVIRONMENTAL DIFFERENCES SOIL MOISTURE Dactylis glomerata Number of samples Ellenberg F Number of samples SEV aeration SEV drought Typical Holcus lanatus Agrostis stolonifera

19 FERTILITY Dactylis glomerata Number of samples Ellenberg N Number of samples Olsen P Kg/ha Typical Holcus lanatus Agrostis stolonifera Confirmed by Olsen available P records Partially reflects different flood duration sediment deposition rates

20 REVISED EXTENT OF MG4 IN UK Map of all known sites supporting MG4.

21 TABLE OF AREAS (SITES WITH > 10 ha listed) Dactylis glomerata Total area (ha) Sites with > 10 ha Clattinger, Grafton Lock, Portholme, Typical Birches Barn, Clattinger, East Cottingwith, Lea Marsh, Mottey meadows, North Meadow, Portholme, Yarnton mead, Upton Holcus lanatus Agrostis stolonifera Ashleworth, Barrow Gravel pits, Lugg Meadows, Pixey Mead, Upton, Shugborough Acaster South Ings, Clifton Ings Loughborough, North meadow, Pixey mead, Wadenhoe Marsh, Wheldrake Ings.

22 EUROPEAN PERSPECTIVE CLOSEST ALLIES New Unit European Equivalent Author Alliance Dactylis Typical Alopecurus false oat grass meadow Arrhenatherum grassland, Colchicum autumnale subcommunity Meisel (1966) (Southern Germany) Gehu (1961) (Belgium & N. France) Holcus Sanguisorba-Silaetum Klapp. ex. Hunt (1964) (Netherlands) Agrostis Fritillario- Alopecuretum- Calthetosum Westhoff and den Held ex. Corporaal, Horsthuis and Schaminee (1993) (Netherlands) Arrhenatherion Arrhenatherion Alopecurion Alopecurion

23 DCA of 72 noda from 6 alliances (including British and European data) The 6 alliances are: 1 Molinion 2 Deschampsion 3 Arrhenatherion 4 Cynosurion 5 Calthion 6 Alopecurion

24 DCA analysis demonstrates clearly the overlap in the floristic composition of the drier alliances as recognised by continental workers - communities assigned to the Cynosurion are almost entirely subsumed within the envelope of the Alopecurion and overlap with the drier Arrhenatherion Molinion Deschampsion Calthion Arrhenatherion Alopecurion Cynosurion

25 Questions