2. ENVIRONMENTAL INFORMATION

2.1 Physical

2.1.1 Climate

This part of Suffolk is one of the driest in the British Isles recording an average of 588mm of rain per year. In recent years the area has suffered extended periods of drought. The months of February to May normally have the lowest rainfall and this often coincides with a period of cooler than national average temperatures. The mean monthly rainfall and temperatures 1965/84 from Aldeburgh and the mean temperature from Lowestoft 1951/80 are shown below:

Average monthly rainfall and temperature

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Rainfall

mm

52

41

42

39

43

40

50

44

54

51

66

55

Temp

Celsius

3

4

5

7

11

14

16

16

15

12

7

5

2.1.2 Hydrology

Maps 7 and 8 show the principal rivers and dykes,permanent and temporary open water,control structures and monitoring points as marked by the

A Main sluice on River Hundred controlled by NRA.

B Abandoned sluice to control River Hundred and RSPB marshes. Permission granted by NRA for RSPB to use to alleviate high water levels on marshes.

C Sluice to control water outflow from RSPB marsh system. Under total control of RSPB.

D Culvert under central bank to drain south marsh into River Hundred.

E Culvert under disused railway line to drain wet area on west side of railway line.

F Sluice.culvert which can be blocked to hold water on north marsh.

G Weir to direct flow of River Hundred into Thorpeness to September,owned and controlled by G.S.Ogilvie.

H Float pump to drain south dyke into bunded marsh system.

I Area of permanent open water. 

2.1.3 Geology

Suffolk lies on the edge of the northern limb of the London Basin and extensive chalk deposits slope gently down from the west to underlie the area of the reserve. Later Cainozoic sediments were formed here and Coralline Crag underlies the area. This crag underlies glacial sands and gravels with alluvium and clay deposits on the fen and marshes. Since the revision of the Plio-Pleistocene boundary at the 1948 International Geological Congress in London this Coralline crag deposit is the only Pliocene formation in Britain though only remnants of this formerly more extensive deposit exist. The beach is a shingle bar which several hundred years ago extended across the mouth of the tidal estuary known as the Haven. The shingle ridge is in the main natural though there may have been some artificial grading of the bank following the floods of 1953.

2.14 Soils

Expanses of fine sand and gravels overlie the crag deposits which stretch along the coast from Landguard to Great Yarmouth. The heath itself is fine acid sand while the marshes are made up of a silty,clay loam.

2.2 Bioloqical

2.2.1 Habitats

Habitat

Features

ha

Compartments

Woodland

mixed, semi-natural, high forest

56.5

A.1.3.1.1

Scrub

dense, coninuous, neutral

6.00

A.2.1.2

Grassland

acid, semi-improved, lowland

79.0

B.1.2.2

Grassland

neutral,semi-improved, lowland

97.5

B.2.2.2

Tall herb

bracken

63.5

C.1.1

Heathland

dry dwarf shrub heath, acid

15.0

D.1.1.2

Swamp/fen

single species dominant fen

28.0

F.1.1

Coastland

shingle, gravel

13

H.3

Total

358.5

2.2.2 Flora

Vascular Plants

351 species have been recorded since 1990 ( Ausden 1990 & Macklin 1995 ).

Species of Note

Parapholis incurva (Cat NSC)

Ranunculus baudotdi (Cat NSC)

Crambe maritima (Cat NSC)

Trifolium

ornithopodioides (Cat NSC)

glomeratum (Cat NSC)

suffocatum (Cat NSC)

Lathyrus japonicus (Cat NSC)

Crassula tillaea (Cat NSC)

Sonchus palustris (Cat NSC)

Dactylorhiza incarnata (Cat REG)

Ranunculus lingua (Cat REG)

Non-Vascular Plants

Ferns & Horsetails - 8 species recorded (Ausden 1990 & Macklin 1995)

Lichens . - 7 species recorded (Ausden 1990).

Bryophytes 26 species recorded (Ausden 1990).

Fungi -159 species recorded	(Macklin 1993 & Thurlow 1995).

Vegetation Communities

A complete NVC survey of North Warren only was carried out in 1990 by Malcolm Ausden of the Suffolk Wildlife Trust under contract to RSPB.

NVC Veqetation

Community/area ha/percent total area

W1 Salix cinerea-Galium palustre woodland (76.5 3.76)

W6 Alnus glutinosa-Urtica dioica woodland (0.50 0.25)

W10 Quercus roburPteridium aquilinum-Rubus fructicosus agg.woodland (6.77 3.32)

W21 Crataegus monogynaHedera helix scrub (0.24 0.12)

W22 Prunus spinosa-Rubus fructicosus agg.scrub 0.18

W23 Ulex europaeus-Rubus fructicosus agg.scrub (0.52 0.26)

W24 Rubus fructicosus-agg.Holcus lanatus (2.15 1.06)

U1 Festuca ovina-Agrostis capillaris-Rumex acetosella agg.grassland (35.02 17.19)

U20 Pteridium aquilinum-Galium saxatile (17.48 8.58)

H1 Calluna vulgaris/Festuca ovina heath (0.03 0.01)

MG1 Arrhenatherum elatius coarse grassland (4.48 2.2)

MG1/U1 Arrhenatherum elatius/Festuca ovina mixed grassland (0.48 0.24)

MG13 Agrostis stolonifera/Alopecurus eniculatus inundation grassland 84.73 41.60)

X Indeterminate grassland (4.18 2.05)

S4 Phragmites australis swamp and reedbeds (21.97 10.79)

S25 Phragmites australis-Eupatoria cannabinum fen (0.13 0.06)

SM16 Festuca rubra saltmarsh (1.42 0.70)

SM24 Elymus pycnanthus saltmarsh (1.38 0.68)

Arable (14.29 7.02)

NVC Ditch Community ((Ditch length(km)/percent total))

A2 Lemna minor community (1.06 9.71)

A3 Spirodela polyrhiza-Hydrocharis morsus-ranae community (0.15 1.37)

A5 Ceratophyllum demersum community (0.91 8.53)

A11 Potamogeton pectinatusMyriophyllum spicatum community 4.11 37.64)

A12 Potamogeton pectinatus community (0.58 5.31)

S4 Phragmites australis swamp and reedbeds (2.35 21.52)

S20 Scirpus lacustris ssp.tabernaemontani swamp (0.18 1.65)

S21 Scirpus maritimus swamp (0.13 1.19

YO Indeterminate community (1.45 13.28)

2.2.3 Fauna

Birds:-

262 species have been recorded on the site and 107 species have bred or attempted to breed.

Breeding- RDB- North Warren

Species

1991

1992

1993

1994

1995

Woodlark

0

5

3

7

11

Turtle Dove

13

16

12

18

22

Skylark

39

38

41

52

73

Spotted Flycatcher

1

1

1

1

1

Linnet

11

15

23

31

35

Song Thrush

9

11

10

10

17

Reed Bunting

9

11

16

21

22

Bullfinch

6

7

8

12

12

Breeding- RDB- Aldringham Walks 1995

Grey Partridge

3

Nightjar

4

Woodlark

11

Turtle Dove

3

Skylark

6

Linnet

11

Song Thrush

3

Breedinq - RDB Amber - Aldrinqham Walks 1995

Sspecies

1991

1992

1993

1994

1995

Blackbird

40

52

56

60

64

Dunnock

66

48

79

76

100

Gadwall

10

8

7

13

11

Garganey

0

1

0

0

0

Goldfinch

3

0

2

5

6

Grasshopper Warbler

4

2

2

3

3

Green Woodpecker

9

9

10

12

13

Kestrel

3

4

4

5

6

Kingfisher

1

2

2

0

0

Lapwing

25

38

45

54

51

Little Tern

4

0

0

0

15

Marsh Harrier

1

0

0

0

0

Marsh Tit

5

6

4

5

5

Nightingale

11

19

14

17

15

Oystercatcher

1

1

2

1

2

Redshank

13

28

32

23

24

Ringed Plover

0

0

0

0

1

Savi's Warbler

0

0

1*

0

0

Shelduck

21

19

15

23

24

Shoveler

3

2

3

4

4

Snipe

5

11

9

7

6

Stonechat

2

0

0

0

0

Swallow

0

0

0

1

0

Teal

11

1

7

2

9

Water Rail

3

0

2

2

3

Willow Tit

1

0

0

0

0

Woodcock

0

0

1

0

0

* denotes singing male only

Breeding- RDB- Amber Aldringham Walks 1995

Blackbird

31

Dartford Warbler

1

Dunnock

33

Goldfinch

4

Green Woodpecker

4

Kestrel

1

Nightingale

5

Stonechat

1

Breedinq - Other Key Species - North Warren

Species

1991

1992

1993

1994

1995

Red-legged Partridge

4

7

7

8

0

Sedge Warbler

45

44

51

78

120

Wheatear

1

0

0

0

2

Whitethroat

50

68

83

103

126

Yellow Wagtail

2

0

0

0

2

 

Breeding- Other Key Species- Aldringham Walks 1995

Red-legged Partridge

9

Whitethroat

64

 

Wintering - RDB Amber - North Warren

Species

1991

1992

1993

1994

1995

Barnacle Goose

3

3

20

18

18

Bean Goose

0

3

3

3

13

Bewick's Swan

36

60

40

49

26

Black-tailed Godwit

1

11

17

12

80

Brent Goose

11

21

100

700

200

Curlew

41

61

86

31

73

Dunlin

700

1000

400

850

800

Gadwall

82

120

73

126

131

Golden Plover

50

30

106

11

25

Greylag Goose

100

163

220

147

400

Lapwing

725

1200

1600

2240

2200

Oystercatcher

8

5

6

7

6

Pink-footed Goose

1

2

2

7

4

Pintail

1

22

45

14

30

Pochard

18

17

18

6

3

Ringed Plover

104

100

122

113

126

Shoveler

100

133

185

264

217

Snipe

250

240

240

200

80

Teal

443

800

910

820

940

White-fronted Goose

17

15

148

120

200

Whooper Swan

0

13

7

7

0

Wigeon

800

1000

1320

1740

1600

 

Mammals

29 species recorded.

Serotine:- A roost occurs in the roof of Shellpits cottages on Aldringham Walks ( EN 1993 ).

Otter:- The relict population became extinct in 1976 and recent records probably refer to individuals moving out of the release site at Minsmere. Two animals were seen together in March 1995 and a spraint was found in the summer of that year.

Fish

Four species have been recorded.

Roach ( Rutilus rutilus ). Tench ( Tinca tinca ). Eel ( Anguilla anguilla ). Three-spined Stickleback ( Gasterosteus aculeatus ).

Reptiles

Three species have been recorded

Adder (Vivipera berus)

Common Lizard (Lacerta vivipara)

Slow worm (Anguis fragilis)

Amphibians

Three species have been recorded

Common frog (Rana temporaria)

Common toad (Bufo bufo)

Palmate newt (Triturus helveticus)

Invertebrates- butterflies

32 species have been recorded

Key species- five year index

Species

1991

1992

1993

1994

1995

Essex Skipper

198

299

202

196

109

Green Hairstreak

5

8

24

25

52

Holly Blue

59

16

4

0

1

Purple Hairstreak

2

5

9

2

4

Brown Argus

0

0

0

0

12

Grayling

180

145

217

195

193

Invertebrates - Moths

Extensive recording has been carried out on the reserve,on the shingle beach and on Aldringham Walks since the early 1960's. Many rare and notable species have been found and some are listed in the EN Invertebrate Site Register of 26.09.91. 252 species have been recorded.

Invertebrates- Odonata

Common name

Scientific name

GB status

Hairy Dragonfly

Brachytron pratense

Notable/nb

Black-tailed Skimmer

orthetrum cancellatum

Local

Vagrant Darter

Sympetrum vulgatum

Migrant

Yellow-winged Darter

Sympetrum flaveolum

Migrant

Ruddy Darter

Sympetrum sanguineum

Local

 

Invertebrates- Ground Beetles

Amera strenua GB status RDB3 This is usually a saltmarsh species; a new record for Suffolk represents a northern extension to its known UK range.

Invertebrates- Diptera

Phalacrocera replicata RDB3

Stratiomys potamida Notable/nb

2.3 Cultural

2.3.1 Commercial

North Warren and Aldringham Walks are entered into the Suffolk River Valleys Environmentally Sensitive Area and the Countryside Stewardship Scheme

Church Farm marshes are cattle-grazed from May to September and the heath is sheep-grazed throughout the year.

Gross annual income

Activity

£

ESA

28832

Countryside Stewardship

4820

Grazing

4378

Bracken

40

Beach cleaning

2730

Total

40800.50

The 80 ha of heathland at Aldringham Walks has been entered into a Countryside Stewardship agreement from October 1st 1995. This will generate income over ten years of £43875.00 at current rates.

Area under cattle grazing at North Warren - 1995- 104.01 ha

Area under sheep grazing at North Warren - 1995- 40.06 ha

2.3.2 Recreational Use

The heathland at North Warren was used extensively in the past for dog walking,rambling and off-road motorcycling. This area of heathland has been livestock fenced into three sections with an extensive public footpath network. Trespass has almost ceased to be a serious problem with visitors now confined to the footpaths. Unauthorised fishing and trespass on the marshes has been brought under control although some small scale mushroom collecting goes on in the autumn. Vandalism occurs,particularly on the coast road between Aldeburgh and Thorpeness but has been greatly reduced since 1990.

Visitor Numbers at North Warren - 1995 ( Estimated )

Jan Feb Mar APr Mav Jun Jul Auq Sep Oct Nov Dec

300 300 400 600 600 700 700 700 400 400 300 300

Total Visitor Numbers = 5700.

Aldringham Walks has been under RSPB control since October 1995 and suffers from unauthorised access,dog walking,off-road motorcycling and shooting. These unauthorised activities will inevitably diminish as the site is wardened by RSPB.

2.3.3 Research,Survev and Monitorinq

1. September 1990 NVC Vegetation Survey of North Warren Reserve. Carried out by Malcolm Ausden on behalf of Suffolk Wildlife Trust under contract to RSPB.

2. July - September 1993. Study of the Wetland Habitats of North Warren Nature Reserve with particular attention to water level changes and their implications for future management. Carried out by Maria Elena Ares on placement with English Nature.

2.3.4 Main Conservation Management Achieved

Management policies and outcomes

Policy 4.1: Hydrological and grazing management of 102 ha lowland wet grassland (Habitat Action LWG 3.2).

Policy 4.2: Grazing management of 40 ha of acid grassland and heath. (Habitat Action LHE 3.2).

Policy 4.3: Hydrological and vegetation management of 28ha of reedbeds. (Habitat Action REE 2.7).