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Area: 11.2 hectares.

Other Information:

Research site for the Freshwater Biological Association River Laboratory. One of the few river sites with estimates for biomass production and throughput of organic matter.

Reasons for Notification:

A length of chalk-stream with marshland and woodland. The Bere stream is a very typical permanent chalk-stream which has been maintained almost without management in recent years. The adjacent woodland and grassland have a rich flora and fauna.

In the stream the dominant higher plants are chalk-stream water-crowfoot Ranunculus pencillatus var. calcareus and water-cress Nasturtium officinale. Whorl-grass Catabrosa aquatica and horned pondweed Zannichellia palustris are other components. Many of the characteristic algal communities of chalk-streams occur including the spring diatom community with Diatoma vulgare, the lime encrusted epilithic community including Homeothrix spp. and filamentous algae, especially Vaucheria spp. The invertebrates vary greatly according to micro-habitat but are again very typical, including freshwater shrimp Gammarus pulex, mayfly Ephemera danica, blue-winged olive Ephemerella ignita, many species of Simulium and chironomids, Limodrilus hoffmeisteri and Stylodrilus heringianus (tubificid worms). Bullhead Cottus gobio and minnow Phoxinus phoxinus are the most abundant fish, but brown trout Salmo trutta in the deeper sections and young salmon Salmo salar are present. Kingfisher Alcedo atthis occurs and otter Lutra lutra is regularly recorded.

The wet grassland which is dominated by soft rush Juncus effusus and hard rush Juncus inflexus, being subject to calcareous influences from the stream and acid ground water from the adjacent Bagshot Beds, has a diverse flora. There are at least fifteen grasses and ten sedges and herbs include local species such as marsh cinquefoil Potentilla palustris, bogbean Menyanthes trifoliata and bog pimpernel Anagallis tenella. Hollows in this grassland contain acid mire communities dominated by Sphagnum compactum with cross-leaved heath Erica tetralix, cotton grass Eriophorum angustifolium, bog asphodel Narthecium ossifragum and several other typical ‘bog’ species. In certain areas, especially near the stream, taller sedges form dense stands with hemlock water-dropwort Oenanthe crocata. In these areas the scarce scarlet tiger moth Calamorpha dominula is frequent.

The woodland is varied ranging from oak Quercus/ash Fraxinus with hazel Corylus shrub layer in the dryer areas to alder Alnus/sallow Salix carr in the lower-lying wetter parts.