Provisional revision of the MG4 Alopecurus pratensis

Provisional revision of the MG4
Alopecurus pratensis - Sanguisorba officinalis community
Hilary Wallace and Mike Prosser
Ecological Surveys (Bangor) and
Floodplain Meadows Partnership (Open University)
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 1992.
In particular work of Gowing et al. 2002 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.
“ 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
SOURCES OF DATA FOR THE MG4 REVISION
Source
No. sites
No. quadrats
Gowing et al. 2002
16
2330
Other OU
monitoring
programmes
10
972
NVC mapping
exercises
32
1444
Map of all sites used in analysis
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
RESULTS
11 clusters resulted from the progressive amalgamation of the 64 endgroups
Closest NVC
community
Number of
clusters
MG6
Lolium perenne - Cynosurus cristatus grassland
1
MG4
Alopecurus pratensis-Sanguisorba officinalis
grassland
4
MG8
Caltha palustris-Cynosurus cristatus grassland
3
MG4/8
Intermediate between MG4 and MG8
1
MG7C
Lolium perenne-Alopecurus pratensisFestuca pratensis grassland. Filipendula
variant of Gowing et al. 2002
1
Cx-Ag-Sn
Carex spp-Agrostis stolonifera grassland of
Cox and Leach 1995
1
Four clusters, comprising 2503 quadrats, were allocated to the MG4 community.
The remainder have been incorporated into the analysis of damper floodplain
meadow communities.
PROPOSED SUBCOMMUNITIES OF MG4
Subcommunity
Number of
samples
Dactylis glomerata 604
Typical
1018
Holcus lanatus
624
Agrostis stolonifera 257
Mean
species/quadrat
25.3 (9 –41)
22.1 (8 -37)
15.7 (6 -31)
15.6 (6 –26)
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)
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)
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.
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
Holcus lanatus
subcommunity
Lugg Meadows Herefordshire
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
Agrostis stolonifera
subcommunity
East Cottingwith, Yorks
Wheldrake Ings
Agrostis stolonifera
subcommunity
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
SUMMARY OF THE FIELD DIFFERENTIATION OF THE SUBCOMMUNITIES
Dactylis
Typical
Holcus
Agrostis
a
b
c
d
76
89
81
80
52
47
44
15
74
75
67
69
27
45
42
8
17
41
22
18
6
88
81
64
60
51
32
33
33
23
19
17
22
8
(a) plus (b)
Trifolium pratensis
Cynosurus cristatus
Centaurea nigra
Plantago lanceolata
Prunella vulgaris
Cerastium fontanum
Bromus racemosus
Fritillaria meleagris
15
19
(a) Diagnostics
Dactylis glomerata
Trisetum flavescens
Leucanthemum
Arrhenatherum
Ranunculus bulbosus
Heracleum
Briza media
7
11
14
15
Dactylis
Typical
Holcus
Agrostis
a
b
c
d
Dactylis glomerata
Trisetum flavescens
Leucanthemum
Arrhenatherum
Ranunculus bulbosus
Heracleum
Briza media
(c ) and (d)
88
81
64
60
51
32
33
33
23
19
17
22
8
Alopecurus pratensis
Oenanthe silaifolia
Phalaris
Elytrigia repens
(d) Diagnostics
Agrostis stolonifera
Cardamine pratensis
Carex acuta
Carex disticha
Achillea ptarmica
Myosotis laxa
35
64
83
12
6
22
82
16
15
13
29
46
31
72
54
7
10
87
79
34
29
21
14
(a) Diagnostics
7
ENVIRONMENTAL DIFFERENCES
SOIL MOISTURE
Number of
samples
Ellenberg
F
Number of
samples
SEV
aeration
SEV
drought
Dactylis
glomerata
604
5.54
383
0.48
8.70
Typical
1018
5.79
587
1.03
5.40
Holcus
lanatus
624
6.24
344
1.77
5.10
Agrostis
stolonifera
257
6.76
64
2.71
2.99
FERTILITY
Number of
samples
Ellenberg
N
Number of
samples
Olsen P
Kg/ha
Dactylis
glomerata
604
5.01
33
7.65
Typical
1018
5.12
55
9.45
Holcus
lanatus
624
5.49
21
12.51
Agrostis
stolonifera
257
5.38
16
16.22
Confirmed by Olsen available P records
Partially reflects different flood duration – sediment deposition rates
REVISED EXTENT
OF MG4 IN UK
Map of all known sites supporting MG4.
TABLE OF AREAS (SITES WITH > 10 ha listed)
Total area (ha)
Sites with > 10 ha
Dactylis
glomerata
192.2
Clattinger, Grafton Lock, Portholme,
Typical
378.5
Birches Barn, Clattinger, East Cottingwith,
Lea Marsh, Mottey meadows, North Meadow,
Portholme, Yarnton mead, Upton
Holcus
lanatus
197.7
Ashleworth, Barrow Gravel pits, Lugg Meadows,
Pixey Mead, Upton, Shugborough
Agrostis
stolonifera
217.4
Acaster South Ings, Clifton Ings
Loughborough, North meadow, Pixey
mead, Wadenhoe Marsh, Wheldrake Ings.
EUROPEAN PERSPECTIVE
CLOSEST ALLIES
New Unit
European Equivalent
Author
Alliance
Dactylis
Alopecurus false oat
grass
meadow
Meisel (1966) (Southern
Germany)
Arrhenatherion
Typical
Arrhenatherum
grassland,
Colchicum autumnale
subcommunity
Gehu (1961) (Belgium & N.
France)
Arrhenatherion
Holcus
Sanguisorba-Silaetum
Klapp. ex. Hunt (1964)
(Netherlands)
Alopecurion
Agrostis
FritillarioAlopecuretumCalthetosum
Westhoff and den Held ex.
Corporaal, Horsthuis and
Schaminee (1993) (Netherlands)
Alopecurion
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
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
Questions