Area: 17.38 hectares.
Description and Reasons for Notification:
Wareham Common is an area of grazing marsh, divided into three blocks, lying in the flood plain of the River Piddle. The river, a chalk stream in its upper catchment, influences the site with base-rich flood water, whereas the immediate catchment provides acidic ground water from soils derived from the Bagshot Beds. The prevalence of acidic or base-rich waters has resulted in considerable variation in plant communities present. All three areas support herb-rich, unimproved grassland communities which are now uncommon both in Dorset and nationally.
The eastern-most grassland adjoins the River Piddle and is the most frequently flooded in winter. The sward is mesotrophic in character, showing affinities to the crested dog’s-tail – marsh-marigold Cynosurus cristatus – Caltha palustris flooded pasture community type. The dominant grasses are Yorkshire fog Holcus lanatus and meadow fescue Festuca pratensis with rather less crested dog’s-tail and creeping bent Agrostis stolonifera. Cuckooflower Cardamine pratensis and marsh-marigold are frequent.
The northern meadows are more distant from the river and show more influence of acidic drainage water. Jointed rush Juncus articulatusand soft rush J. effusus are abundant in the sward with occasional purple moor-grass Molinia caerulea. Carnation sedge Carex panicea and common sedge C. nigra are frequent, as are the herbs devil’s-bit scabious Succisa pratensis and meadow thistle Cirsium dissectum. Of particular note is the presence of the nationally scarce whorled caraway Carum verticillatum, know only from one other Dorset site, and the abundance of the moss Climacium dendroides in the sward.
The western-most grassland is the most heavily influenced by the acidic catchment and supports a fen meadow community of the uncommon purple moor-grass – meadow thistle type. Purple moor-grass is abundant and quaking grass Briza media, heath grass Danthonia decumbens and sweet vernal grass Anthoxanthum odoratum are all frequent. Common sedge, carnation sedge and yellow sedge C. demissa are also common. The sward has a high proportion of herbs with devil’s-bit scabious, lousewort Pedicularis sylvatica, marsh pennywort Hydrocotyle vulgaris and bog pimpernel Anagallis tenella. The lower lying areas have marsh cinquefoil Potentilla palustris, whilst a more acidic character is reflected in the local occurrence of bog mosses Sphagnum spp., Round-leaved sundew Drosera rotundifolia and small quantities of cross-leaved heath Erica tetralix and petty whin Genista anglica.
Ditches are present in all three sections and contribute to the floristic and faunal interest of the site. Plants occurring in these ditches include broad-leaved pondweed Potamogeton natans, arrowhead Sagittaria sagittifolia, water dock Rumex hydrolapathum, whorl-grass Catabrosa aquatica and floating club-rush Eleogiton fluitans.
The fauna of the site is not known in detail but the ditches support a variety of dragonflies and the meadows have strong populations of grasshoppers including lesser marsh grasshopper Chorthippus albomarginatus.