River Stour (Kent) InternalRiver Drainage Board – Biodiversity Stour Action Plan (Kent) Internal Drainage Board Stodmarsh National Nature Reserve Biodiversity Action Plan 2021-2025 1 River Stour (Kent) Internal Drainage Board – Biodiversity Action Plan 1. Introduction ........................................................................................................................................ 1 1.1. What is Biodiversity and why is it important? ....................................................................... 1 1.2. Legislative Background ......................................................................................................... 1 1.3. Policy & Strategic Background.............................................................................................. 2 1.4. Purpose ................................................................................................................................. 3 1.5. Vision ..................................................................................................................................... 3 1.6. Aims ....................................................................................................................................... 3 2. The IDB BAP Process ........................................................................................................................ 5 2.1. The Biodiversity Audit............................................................................................................ 5 2.2. Objectives, Targets and Actions ........................................................................................... 5 2.3. Monitoring and Reporting ...................................................................................................... 5 3. The Biodiversity Audit ....................................................................................................................... 6 3.1. The River Stour (Kent) Internal Drainage District ................................................................. 6 3.2. Map of Audit Area (Drainage District) ................................................................................... 7 3.3. Geology ................................................................................................................................. 8 3.4. Landscape Character ............................................................................................................ 8 3.5. Landscape Designations ..................................................................................................... 11 3.6. Sites and Monuments.......................................................................................................... 11 3.7. Tree Preservation Orders.................................................................................................... 13 3.8. Statutory Nature Conservation Sites .................................................................................. 13 3.8.1 Internationally Designated Sites ............................................................................................ 13 3.8.2 Nationally Designated Sites................................................................................................... 14 3.8.3 Non-statutory Nature Conservation Sites.............................................................................. 16 3.9. Habitat Audit Summary ....................................................................................................... 18 3.10. Species Audit Summary .................................................................................................... 20 3.11. Invasive Non-native Species Summary ............................................................................ 29 3.12. Water Level Management Plans....................................................................................... 31 4. Habitat and Species Action Plans.................................................................................................. 32 4.1. Introduction .......................................................................................................................... 32 4.2. Habitat Action Plans ............................................................................................................ 32 4.2.1 Drainage Ditches and Associated Linear Features .............................................................. 32 4.2.1.1.1 IDB Actions ...................................................................................................................... 34 4.2.2 Floodplain Wetlands .............................................................................................................. 37 4.3. Species Action Plans........................................................................................................... 40 4.3.1 Vascular Plants ...................................................................................................................... 40 4.3.2 Shining Ramshorn Snail.................................................................................................... 43 4.3.3 White-Clawed Crayfish...................................................................................................... 46 4.3.4 Dragonflies and Damselflies ............................................................................................. 49 4.3.5 Fish .................................................................................................................................... 52 4.3.6 Amphibians ........................................................................................................................ 55 4.3.7 Reed-nesting Birds............................................................................................................ 58 4.3.8 Water Vole ......................................................................................................................... 61 4.3.9 Otter ................................................................................................................................... 65 River Stour (Kent) Internal Drainage Board – Biodiversity Action Plan 4.3.10 Water Fern (Azolla) ......................................................................................................... 68 5. Procedural Action Plan ................................................................................................................... 71 5.1. Introduction .......................................................................................................................... 71 5.2. Objectives and Targets ....................................................................................................... 71 5.3. IDB Actions .......................................................................................................................... 72 6. Summary of Priority Actions .......................................................................................................... 73 7. Implementation................................................................................................................................. 75 7.1. Overview.............................................................................................................................. 75 7.1.1 Land management (channel maintenance etc.).................................................................... 75 7.1.2 Survey and Monitoring........................................................................................................... 75 7.1.3 Policy, advisory, communications, publicity .......................................................................... 76 7.1.4 Partnership actions ................................................................................................................ 76 7.2. Land Management .............................................................................................................. 76 7.2.1 Channel management guidelines .......................................................................................... 76 7.2.2 Physical channel enhancement guidelines ........................................................................... 81 7.2.3 Water level management and biodiversity guidelines........................................................... 84 7.2.4 Tree-work guidelines ............................................................................................................. 86 7.2.6 Targeting management.......................................................................................................... 90 7.3 Survey and monitoring ......................................................................................................... 94 7.3.1 Ecological assessment of drainage district and watercourse management prescriptions ... 94 7.3.2 Species surveys..................................................................................................................... 96 7.3.3 Gaps in knowledge ................................................................................................................ 97 7.4 Advisory/awareness raising ................................................................................................. 98 7.4.1 Information for landowners .................................................................................................... 98 7.4.2 Information for general use.................................................................................................. 100 7.4.3 Agri-environment schemes .................................................................................................