Norfolk & Suffolk Team
Dragonfly House
2 Gilders Way
Norwich
Norfolk NR3 2UB
Tel No 0845 600 3078
Email:
CONSERVATION OBJECTIVES and DEFINITIONS OF FAVOURABLE CONDITION for DESIGNATED FEATURES OF INTEREST:
These Conservation Objectives relate to all designated features on the SSSI, whether designated as SSSI, SPA, SAC or Ramsar features.
Name of Site of Special Scientific Interest (SSSI)
River WensumNames of designated international sites
Special Area for Conservation (SAC) /River Wensum
Special Protection Area (SPA)
/ N/ARamsar:
/N/A
Relationship between site designations
In relation to the River Wensum SSSI, the boundary of the Wensum SAC is concurrent with the boundary of the SSSI, with the exception that the SAC does not include Site Unit 7.Version Control information
Status of this Version (Draft, Consultation Draft, Final) / Final
Prepared by: / Richard Leishman
Date of this version: / 16 03 11
Date of generic guidance on favourable condition used: / CSM Guidance for Rivers and Streams (Mar 2005)
Other notes/version history :
Quality Assurance information
Checked by / Name: Peter Leverton / Date: 16 03 11
Signature
Peter Leverton
Conservation Objectives and definitions of Favourable Condition: notes for users
Conservation Objectives
SSSIs are notified because of specific biological or geological features. Conservation Objectives define the desired state for each site in terms of the features for which they have been designated. When these features are being managed in a way which maintains their nature conservation value, then they are said to be in ‘favourable condition’. It is a Government target that 95% of the total area of SSSIs should be in favourable condition by 2010.
Definitions of Favourable Condition
The Conservation Objectives are accompanied by one or more habitat extent and quality definitions for the special interest features at this site. These are subject to periodic reassessment and may be updated to reflect new information or knowledge; they will be used by Natural England and other relevant authorities to determine if a site is in favourable condition. The standards for favourable condition have been developed and are applied throughout the UK.
Use under the Habitats Regulations
The Conservation Objectives and definitions of favourable condition for features on the SSSI may inform the scope and nature of any ‘appropriate assessment’ under the Habitats Regulations. An appropriate assessment will also require consideration of issues specific to the individual plan or project. The habitat quality definitions do not by themselves provide a comprehensive basis on which to assess plans and projects as required under Regulations 20-21, 24, 48-50 and 54 - 85. The scope and content of an appropriate assessment [m1]will depend upon the location, size and significance of the proposed project. Natural England will advise on a case by case basis.
Following an appropriate assessment, competent authorities are required to ascertain the effect on the integrity of the site. The integrity of the site is defined in para C10 of PPG9 as the coherence of its ecological structure and function, across its whole area, that enables it to sustain the habitat, complex of habitats and/or the levels of populations of the species for which it was classified. The determination of favourable condition is separate from the judgement of effect upon integrity. For example, there may be a time-lag between a plan or project being initiated and a consequent adverse effect upon integrity becoming manifest in the condition assessment. In such cases, a plan or project may have an adverse effect upon integrity even though the site remains in favourable condition.
The formal Conservation Objectives for European Sites under the Habitats Regulations are in accordance with para. C10 of PPG 9, the reasons for which the European Site was classified or designated. The entry on the Register of European Sites gives the reasons for which a European Site was classified or designated.
Explanatory text for Tables 2a, 2b, 3a, 3b, 3c, 3d, 3e, 3f
Tables 2a, 2b, 3a, 3b, 3c,set out the measures of condition which we will use to provide evidence to support our assessment of whether features are in favourable condition. They are derived from a set of generic guidance on favourable condition prepared by NE specialists, and have been tailored by local staff to reflect the particular characteristics and site-specific circumstances of individual sites. Quality Assurance has ensured that such site-specific tailoring remains within a nationally consistent set of standards. The tables include an audit trail to provide a summary of the reasoning behind any site-specific targets etc. In some cases the requirements of features or designations may conflict; the detailed basis for any reconciliation of conflicts on this site may be recorded elsewhere. Tables 3d, 3e and 3f present non-mandatory objectives which are related to biodiversity hosted by the SSSI.
Conservation Objectives: River Wensum
Final16 03 11 Format Version 2.0 Page 1 of 1
Conservation Objectives
The Conservation Objectives for this site are, subject to natural change, to maintain the following habitats and geological features in favourable condition (*), with particular reference to any dependent component special interest features (habitats, vegetation types, species, species assemblages etc.) for which the land is designated (SSSI, SAC, SPA, Ramsar) as individually listed in Table 1.
Habitat Types represented (Biodiversity Action Plan categories)
Rivers & Streams
Geological features (Geological Site Types)
Not applicable
(*) or restored to favourable condition if features are judged to be unfavourable.
Standards for favourable condition are defined with particular reference to the specific designated features listed in Table 1, and are based on a selected set of attributes for features which most economically define favourable condition as set out in Tables 2a, 2b, 3a, 3b, 3c, 3d, 3e, 3f
Conservation Objectives: River Wensum
Final16 03 11 Format Version 2.0 Page 1 of 1
Table 1 Individual designated interest features
BAP Broad Habitat Type / Specific designated features / Explanatory description of the feature for clarification / SSSI designated interest features / SAC designated interest features / SPA bird populations dependency on specific habitats / Ramsar criteria applicable to specific habitatsAnnex 1 species / Migratory species / Waterfowl assemblage / 1a Wetland characteristics / 2a Hosting rare species &c / 3a 20000 waterfowl / 3c 1% of population
Rivers & Streams / Type I GroupA1c-fenland river
Type III Group AIIIb-chalk river
N.B. Any sections classified as Type IV are considered to be in unfavourable condition. / River & streams / * / *
Water course of plain to montane levels with the Ranunculion fluitantis and Callitricho batrachion vegetation / Aquatic vegetation characterised by species of water-crowfoot and starwort / *
Cottus gobio / Bullhead / *
Lampetra planeri / Brook lamprey / *
Austropotamobius pallipes / White-clawed crayfish / * / *
BAP Broad Habitat Type / Specific designated features / Explanatory description of the feature for clarification / SSSI designated interest features / SAC designated interest features / SPA bird populations dependency on specific habitats / Ramsar criteria applicable to specific habitats
Annex 1 species / Migratory species / Waterfowl assemblage / 1a Wetland characteristics / 2a Hosting rare species &c / 3a 20000 waterfowl / 3c 1% of population
Fen, Marsh & Swamp / S3 Carex paniculata sedge-swamp / Sedge swamp / [*]
S4 Phragmites australis swamp and reed-beds / Swamp and reed-bed / [*]
S5 Glyceria maxima swamp / Swamp / [*]
S7 Carex acutiformis swamp / Swamp / [*]
S25 Phragmites australis-Eupatorium cannabinum tall-herb fen, Cladium mariscus sub-community. / Tall-herb fen / [*]
Vertigo moulinsiana / Desmoulin’s whorl snail / * / *
Broadleaved, Mixed & Yew Woodland / W6 Alnus glutinosa-Urtica dioica woodland / Wet woodland / (*)
Lowland Neutral Grassland / MG8 Cynosurus cristatus-Caltha palustris grassland, MG8-related (south) M22, M23 lowland meadows / Lowland meadows / (*)
Dry Heathland / H8 Calluna vulgaris – Ulex gallii heath / Heathland / (*)
NB. Features where asterisks are in round brackets (*) indicate habitats which are not notified for specific habitat interest (under the relevant designation) but have been included within the boundary of the site, either because they are hydrologically linked to the River Wensum, or in the case of the dry heathland at Great Ryburgh Common, because an area of W10 woodland on ground just outwith the floodplain includes a clearing that supports this habitat. Features where asterisks are in square brackets [*] indicate habitats which are not notified for specific habitat interest (under the relevant designation) but should be regarded as being of special interest as they host populations of Desmoulin’s whorl snail.
Audit Trail
Rationale for the identification of the features of special interest of the SSSI
The features of special interest - The River Wensum SSSI was selected as a ‘whole river SSSI’ (1989 Guidelines on the selection of biological SSSIs: Freshwater habitats – paragraph 6.2.1). It is classified as a JNCC River Type III: “lowland chalk & oolite rivers with generally stable flow regimes” with a transition in its downstream section to Type I “lowland rivers with minimal gradients on mixed geology in England”. In addition the site was submitted to Europe as it supports the Annex I Corine Biotope: Water course of plain to montane levels with the Ranunculion fluitantis and Callitricho batrachion vegetation. This Biotope is the habitat hosted by Type III and Type I rivers and the two JNCC river types and the Annex I habitat they support should be regarded as an interest feature of the SSSI.Of the invertebrates that are present on the site, Desmoulin’s whorl snail and white-clawed crayfish are highlighted as being of particular significance and are two of the European features for which the River Wensum was submitted to Europe as an SAC. Desmoulin’s whorl snail and white-clawed crayfish are should therefore be regarded as separate features of interest in their own right.However, it should be noted the invertebrate assemblage is not regarded as an interest feature of the SSSI.
The remaining two European features hosted by the River Wensum SSSI are bullhead and brook lamprey, and populations of both of these species should also be regarded as features of special interest of the SSSI.
Although the Citation and the Criterion Sheet make reference to the vascular plant assemblage, which includes over 100 species of vascular plants, this assemblage does not support a sufficient number of Nationally Scarce or Nationally Rare species to quality as an interest feature in its own right.
Condition Assessment of River Units - Where the freshwater habitat of a site is designated (as either SSSI or SAC), conservation objectives and associated condition assessment should be based on the relevant generic habitat FCT(s), featuring a range of environmental attributes and consideration of the plant community. If there are additional freshwater species designations on the site, environmental attributes in the relevant species FCTs should only be considered if the generic habitat FCT inadequately safeguards habitat conditions for the species. Bespoke species monitoring would generally only be used as a cross-check on site condition rather than as a routine assessment tool. Therefore, the presumption is that the conservation objectives will be based on the relevant generic habitat FCT, with additional consideration of the environmental targets in generic species FCTs only where the habitat FCT is inadequate to protect the relevant species.
Bullhead (Cottus gobio), Brook lamprey (Lampetra planeri), and White-clawed crayfish (Austropotamobius pallipes), are all species which are associated with and dependant on the Annex I Corine Biotope: Water course of plain to montane levels with the Ranunculion fluitantis and Callitricho batrachion vegetation and it is therefore deemed appropriate for the condition of the river units to be determined through an assessment of the condition of this biotope. Non-mandatory methodologies for the assessment of these species are presented in Tables 4a, 4b, 4c & 4d.
Condition Assessment of terrestrial units - In accordance with the 1989 Guidelines, the River Wensum SSSI also includes areas of adjoining terrestrial habitat. The guidelines state that, “Any adjacent semi-natural, wet habitat which is intimately linked with the river and which is probably dependent on the river for its continued existence should be included within the SSSI boundary. Such areas may be unimproved alluvial flood-plain meadows, marshland, wet heathland, fens, bogs, flushes, swamps and wet woodland such as willow and alder carr.” It can therefore be inferred that:
- The River Wensum SSSI was selected for the aquatic and emergent communities that the river supports and was not selected for the presence of specific grassland, fen or mire communities that are present on those areas of the floodplain included within the boundary of the site. In order to qualify for inclusion within the site boundary, terrestrial compartments were selected against less stringent criteria than is the case for the selection of sites supporting specific vegetation communities associated with floodplain habitats.
- The terrestrial compartments were selected because they are semi-natural and because they are hydrologically linked with the river. This defines their special interest. Their inclusion within the boundary of the site was necessary in order to represent the range of floodplain habitats associated with the river to maintain selected areas from the overall mosaic of habitats within the floodplain.
The exceptions to this rationale are the habitats that support Desmoulin’s whorl snail. Desmoulin’s whorl snail is the only one of the European features which is associated with habitats that occur on the terrestrial compartments. The favourable condition tables for this snail indicate that its status can be maintained by ensuring that the appropriate vegetation communities that support this feature are maintained. While these tall herb swamp and fen communities are not features of special interest in their own right, monitoring of their extent and structure will be necessary in order to evaluate the favourable condition of this species on the site.
Table 2 Habitat Features - Extent Objectives
Conservation Objective for habitat extent / To maintain the designated habitats in favourable condition, which is defined in part in relation to a balance of habitat extent (extent attribute). Favourable condition is defined at this site in terms of the following site-specific standards:Extent - Dynamic balance / On this site favourable condition requires the maintenance of the extent of each designated habitat type. Maintenance implies restoration if evidence from condition assessment suggests a reduction in extent.
Habitat Feature (BAP Broad Habitat level, or more detailed level if applicable) / Estimated extent (ha) and date of data source/estimate / Site Specific Target range and Measures / Comments
Rivers & Streams
Watercourses Characterised by Ranunculion fluitantis
and Callitricho-Batrachion Vegetation. / 71 kilometres / Much of the river is over-widened, over-deepened, and impounded. As a result the area of watercourse has been artificially enlarged. As river restoration is implemented, and the impounding impacts of structures reduced, so the quality of the river habitat will improve, while paradoxically its area will diminish. It is therefore more appropriate to provide data on the length of watercourse, rather than its area.
Where river restoration occurs, this may involve diverting the river from engineered channels, and back into earlier river channels. As little of the floodplain is included within the boundary of the SSSI, this involves diverting the river outwith the designated boundary.
Where the river has been diverted from the notified boundary of the SSSI, and designated boundary of the SAC, any proposals of owners / occupiers / statutory bodies to modify these channels require Section 28E consent, or Section 28G assent, unless the proposed activities are permitted under other mechanisms, in which case Natural England would be consulted in relation to Section 28I advice. / It is expected that environmental targets laid down by the FCT will be complied with throughout the site.
This has implications with regard to the targeting of HLS on the whole of the floodplain of the River Wensum, and on the evaluation of management of banks and watercourses connected to the River Wensum as practiced on land within existing agri-environment agreements.
It should be noted that the tributaries of the Wensum, that have not been included within the boundary of the SSSI also support the habitats and species for which the site was notified. These tributaries therefore have a strong relationship with the integrity of the river as a whole.
The appropriate survey methodologies for Watercourses characterised by Ranunculion fluitantis and Callitricho-Batrachion Vegetation have been assimilated within table 3a - Site-Specific definitions of Favourable Condition for freshwater habitats and species on the River Wensum SSSI.
All river units should be regarded as having the potential to support populations Ranunculion fluitantis
and Callitricho-Batrachion Vegetation.
Fen, Marsh and Swamp
Desmoulin’s whorl snail / - / As indicated above, the individual floodplain communities are not regarded as interest features in their own right. However, those plant communities which support Desmoulin’s whorl snail are regarded as an interest feature by default.
With regard to the area of fen, marsh and swamp, as a whole, there should be a presumption against the loss of these important BAP habitats.
However, in the case of those fen, marsh and swamp communities which support Desmoulin’s whorl snail, there should be no reduction in the total combined extent of wetland. No more than 25% reduction from baseline in core habitat area or abundance of food plant.