Securing Biodiversity in Breckland - European Commission

edstraw Galium parisiense (Tansley and Watt, undated). We do not know of a single localityremaining in Breckland where such an assemblage could be found today.From these independent lines of qualitative evidence, it is likely that many species that depend onphysically disturbed and grazed conditions and a continuous supply of bare sand or chalky soil, willhave suffered severe and profound declines in their extent and abundance.Recognising Changes in Vegetation Over Time: an Example of Grass-Heath VegetationRodwell (1992) analysed samples of CG7b (the Cladonia spp. Sub-community of Festuca ovina-Hieracium pilosella-Thymus praecox/pulegoides grassland Table 3, classified by Watt as his ‘grasslandB’) obtained in the mid 1970s. Rodwell commented on marked changes since Watt’s time (e.g. Watt1940, 1957). Notably, Rodwell commented that “the vegetation is now generally grassier” withapparently greater amounts of more mesic grass species such as Holcus lanatus and Trisetumflavescens as well as mesic herbs such as Trifolium repens. Second, Rodwell commented that thetherophytes (small annual plants that require small scale disturbance and open swards, for exampleparsley-piert Aphanes arvensis, early forget-me-not Myosotis ramosissima, wall speedwell Veronicaarvesnsis, annual pearlwort Sagina apetala, shepherds cress Teesdalia nudicaulis and springspeedwell Veronica verna) were “now apparently much rarer”. This situation is compatible with areduction in the frequency of small scale disturbance, most likely due to a reduction in rabbitpopulations, and also with an accumulation of nutrients and/or closed matted swards. However, thesamples analysed by Rodwell also showed “marked reductions in the frequency and variety ofbryophytes and lichens” (Rodwell 1992). This is compatible with both a decrease in grazing intensityand an increase in nutrient status.Rodwell did note caution in interpreting too much from a single snapshot in time – however, it isnotable that these data were collected in the drought year of 1976 which would have hit mesicspecies hard and would not explain a reduction in lichens (although annuals may have been crispedup and hard to detect by summer).There seems to be a consistent and continuing pattern of deterioration of the grass-heath resource,as shown by measured change and perception of change across successive periods. This hascontinued in the last 20 years despite the restoration of livestock grazing across most grass-heaths.The evidence is summarised below.111