Eutrophic Standing Water Ponds
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Buckinghamshire & Milton Keynes Biodiversity Action Plan Eutrophic Standing Water Habitat Action Plan Ponds Habitat Action Plan Eutrophic Standing Water Ponds Key associated species Bewick’s Swan Reed Bunting Brown Galingale Reed Warbler Common Frog Shoveler Common Toad Smooth Newt Great Crested Newt Starfruit Mudwort Water Rail Mute Swan Water Vole Otter Freshwater White-clawed Crayfish Pintail Wigeon Eutrophic Standing Water includes natural systems such as lakes and pools and man-made waters such as ditches, reservoirs, canals, balancing lakes, gravel, clay and chalk pits. BAP Priority Habitat Ponds are defined as permanent and seasonal standing water bodies up to 2ha in extent which meet one or more of the following criteria. • Habitats of high conservation importance. Ponds that meet criteria under Annex 1 of the Habitats Directive. • Species of high conservation importance. Ponds supporting Red Data Book species, BAP species, species fully protected under the Wildlife and Countryside Act Schedule 5 and 8, Habitats Directive Annex II species, a Nationally Scarce wetland plant species, or three Nationally Scarce aquatic invertebrate species. • Exceptional assemblages of key biotic groups: Ponds supporting exceptional populations or numbers of key species. Based on (i) criteria specified in guidelines for the selection of biological SSSIs (currently amphibians and dragonflies only), and (ii) exceptionally rich sites for plants or invertebrates (i.e. supporting ≥30 wetland plant species or ≥50 aquatic macroinvertebrate species). • Ponds of high ecological quality: Ponds classified in the top PSYM category (“high”) for ecological quality (i.e. having a PSYM score ≥75%). [PSYM (the Predictive SYstem for Multimetrics) is a method for assessing the biological quality of still waters in England and Wales. Plant species and / or invertebrate families are surveyed using a standard method. The PSYM model makes predictions for the site based on environmental data and using a minimally impaired pond dataset. Comparison of the prediction and observed data gives a % score for ponds quality.] • 1 Buckinghamshire & Milton Keynes Biodiversity Action Plan Eutrophic Standing Water Habitat Action Plan Ponds Habitat Action Plan • Other important ponds: Individual ponds or groups of ponds with a limited geographic distribution recognised as important because of their age, rarity of type or landscape context e.g. pingos, duneslack ponds, machair ponds. Such habitats support an enormous variety of plants and animals, from microscopic plants and animals to larger species such as Great Crested Newt, Water Rail and Water Vole. Nutrient status is an important determining factor for the range of species found in eutrophic standing water, as well as depth, edge habitats, bank slope and seasonal water level variation. 1 Current status in the UK Biological status 1.1 Eutrophic waters are naturally rich in plant nutrients and are typical of lowland Britain. These waters support large amounts of vegetation and a wide variety of animals. Many are important breeding and wintering sites for waterfowl. Characteristic plants include duckweeds, yellow water lily, spiked water-milfoil and fennel pondweed. 2 Current status in Buckinghamshire Cover and distribution 2.1 The County supports a number of large areas of eutrophic standing water, comprising gravel pits, reservoirs, canals and lakes. These habitats support a wide variety of wildlife, much of which is restricted to this habitat type. Eutrophic standing water provides important habitat for, in some cases, nationally important numbers of over-wintering wildfowl. Key species include Shoveler and Bewick’s Swan. Otter and Water Vole are notable mammal species found in this type of habitat. 2.2 We can estimate that the county contains between 2000 and 6000 ponds, especially on farmland and on common land, used or previously used to water livestock. These ponds provide habitat for a variety of specialist flora and fauna including all three species of British newt. Gravel pit restoration has helped offset loss of pond habitat for mobile species such as birds. However, local losses of flora and more sedentary fauna will have resulted from the large number of pond losses. 2.3 The total area of open water associated with SSSIs is just over 50 ha. All the SSSI reservoirs are important for their populations of over- wintering wildfowl. Foxcote Reservoirs and Woods SSSI support at least 10 species which are regular winter visitors. Shoveler duck and Bewick’s Swan have reached 1% of the total GB wintering populations. 2 Buckinghamshire & Milton Keynes Biodiversity Action Plan Eutrophic Standing Water Habitat Action Plan Ponds Habitat Action Plan 2.4 There are large areas of open water on the County boundaries. Tring Reservoirs SSSI (106.5 ha) in Hertfordshire supports the nationally scarce plant mudwort. Mid Colne Valley SSSI (London Borough of Hillingdon, 132 ha) supports over 70 breeding and 80 wintering bird species. 2.5 The Wildlife Trust nature reserves include some prominent eutrophic open water habitat, including Calvert Jubilee Pit (20 ha), Boarstall Duck Decoy (1 ha), the Buckingham Canal (1 ha), Weston Turville reservoir and College Lake Wildlife Centre. 2.6 Parts of the Grand Union Canal are designated as Local Wildlife Sites while other stretches of the main canal and its tributary Arms (Aylesbury, Slough and Wendover) are currently Biological Notification Sites. Trends 2.7 Eutrophic standing water areas have increased due to the flooding of former gravel, clay and chalk workings in the last 30-40 years. This increase has helped to compensate for the significant decrease in ponds and ditches that has resulted from changes in agricultural practice. 2.8 The floodplain forest development at Wolverton in the Ouse Valley will add a further significant area of eutrophic open water. 2.9 Results from a survey by the NCC using aerial photography to study landscape change from 1947 to 1985 showed 64% of ponds had been lost. A later study using aerial photography confirmed the extent of the loss, some 5,000 ponds. Ground survey confirmed that ponds that exhibit scrub encroachment, as elucidated via aerial photographic assessment, are likely to have little or no water. 3 Current factors affecting the habitat Changes in the water table 3.1 Lowering of the water table through over abstraction of the surface and ground water, drainage works and flood management can lead to habitat degradation. Eutrophic standing water features reliant on rainfall may also have been adversely affected by recent climate change, although there is as yet insufficient evidence to support this. Pollution 3.2 This can include eutrophication from fertiliser run-off, chemical spillage and increased levels of effluent from sewage and water treatment works. 3 Buckinghamshire & Milton Keynes Biodiversity Action Plan Eutrophic Standing Water Habitat Action Plan Ponds Habitat Action Plan Land conversion of pasture to arable 3.3 Pond loss predominantly results from conversion of pasture to arable use. Mains water supply for livestock has supplanted the need for many field ponds. Lack of management has resulted in scrub encroachment and eventual pond loss. Recreation 3.4 Standing water bodies with easy access can suffer disturbance from recreational activities. Intensive management for fisheries and wildfowling reduces biodiversity. Alien species 3.5 Water bodies can be subject to invasion by alien species such as Canadian pondweed, New Zealand Pigmyweed, Parrot’s-feather and Water Fern. 4 Current action Legal status 4.1 The majority of the larger eutrophic standing water sites are designated as SSSIs. Many of the remaining sites are managed as part of nature reserves. Farm ponds have no protection unless the land is managed as part of a management agreement. Former common ponds are generally in decline unless they are managed. Management, research and guidance 4.2 Grant aid from Countryside Management Projects, FWAG and Countryside / Environmental Stewardship has helped to restore many ponds throughout the County. Ditch management is offered as an option in Entry Level Stewardship, while pond management is only covered by Higher Level Steawardship. 4.3 Higher Level Stewardship grants are available for waterside land, reflecting the importance of water to wildlife. 5 Objectives 5.1 It is important that Habitat Action Plan objectives and actions are considered conjunction with those in Generic Issues (see Generic Issues). All Generic objectives and actions apply to each individual Habitat Action Plan. 5.2 The Eutrophic Standing Waters Hap will contribute to the following UK BAP targets T1 - Maintain the condition of all eutrophic standing waters of known conservation importance currently judged in good condition 4 Buckinghamshire & Milton Keynes Biodiversity Action Plan Eutrophic Standing Water Habitat Action Plan Ponds Habitat Action Plan T2 - Achieve good condition by 2010 in x sites of conservation importance that have been damaged by human activity T3 - Improve the condition by 2010 of a further x sites of conservation importance that have been damaged by human activity T4 - Maintain the condition of remaining eutrophic standing waters of known conservation importance T5 - Prevent further deterioration in condition of the remaining standing eutrophic waters T6 - Undertake restoration measures by 2010 on x sites which have become so degraded that they no longer constitute a eutrophic standing water The Ponds HAP will contribute to the following