Securing Biodiversity in Breckland - European Commission

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Nitrogen Deposition: Potential Impacts and MitigationGrass-heath communities depend on low nutrient conditionsEricoid (heather) heathland vegetation, in common with chalk grassland, dune and grass-heathvegetation, depends on the low nutrient status of the soil for the characteristic stress tolerant plantcommunities to persist. With increased nutrients, less competitive stress-tolerant species arereplaced by more vigorously competitive species. The diversity and composition of vegetation isfundamentally altered, generally resulting in a loss of scarce species, low growing species, lichens andbryophytes.Experimental work conducted in the Netherlands has shown the susceptibility of heather heathlandvegetation to increased nitrogen deposition, with dwarf shrub heather species being replaced byperennial grass species as nitrogen loads increase (Berendse et al. 1993). Effects include thereplacement of ling heather Calluna vulgaris by wavy-hair grass Deschampsia flexuosa on dry heaths(Heil and Diemont 1983) as well as replacement of both ling heather Calluna vulgaris and crossleavedheather Erica tetralix by purple moor grass Molinia caerulea on damp or wet heaths (Heil andBruggink 1987; Aerts et al. 1990; Berendse 1990; Berendse et al. 1993).Experimental work shows that addition of either phosphorous or nitrogen to calcareous Brecklandgrass-heath vegetation results in greater dominance and growth of perennial grasses and loss oflichens and other low-growing stress-tolerant plants, together with a reduction in vascular plantdiversity in the sward (Davy and Bishop 1984). Similar effects have been demonstrated onecologically similar habitats , including sand dune vegetation, with a decline in annual species,mosses and lichens and increase in red fescue Festuca rubra (Willis 1963; Boorman and Fuller 1982),and on calcareous grassland in which Festuca rubra became vigorous and dominant (Smith, Elstonand Bunting 1971).In Breckland, nitrogen appears to be the primary limiting nutrient (Davy and Bishop 1984), as bothsand dune soils (Boorman and Fuller 1982) and chalk grasslands (Bobbink et al. 1989). Unpublishedwork carried out by P. Dolman and S. Lake showed that diverse lichen-heath sub-communities of U1acid grassland occurred on soils that were higher in phosphorous than grass dominated subcommunities,as long as their nitrogen status was very low. The effects of nitrogen enrichment arepartially linked with those of grazing (Berendse 1985). Work by both Davy and Bishop (working atDeadman's Graves, Breckland) and Boorman and Fuller (working on dune vegetation on the Norfolkcoast) showed that grazing was not sufficient to offset the impacts of nitrogen addition on lichen richgrass-heath.Increased nitrogen deposition in the UK and BrecklandThere has been a very large reduction in the emissions of nitrogen attributable to domestic coal sincethe peak of that source in c.1900. Despite this, overall reduced nitrogen (NH 3 and NH 4 +) emissionshave continued to increase throughout 1900-2000 due to large increases from the agricultural sector(Fowler et al. 2004). Oxidised nitrogen emissions (NO 3 - , NO 2 and HNO 3 ) form c80% of total emissionsand have decline since a peak in 1980. Overall emissions have thus declined in recent decades(Fowler et al. 2004).98
Ariel depositions to agricultural soils are small in relation to fertiliser inputs. However, deposition tosemi-natural soils may be very important in modifying the carbon economy as well as in changing thespecies composition of the flora (Pitcairn et al. 1998). Depositions during the last century (1900-2000) were equivalent to an average of 1.2 t N ha −1 (range, 1 t N ha -1 to 5 t N ha -1 at national and localscales) and appears to be accumulating in soils (Fowler et al. 2004) (Figure 19). Deposition inBreckland over the century ranged 1-2tNha -1 . Rates of nitrogen deposition in Breckland were higherthan in other areas of the country. In the mid 1990s, Breckland had rates of nitrogen depositionalmost double those measured in Dorset (Pitcairn, Fowler and Graze 1995).Intensive livestock units release ammonia gas that can cause severe localised impacts on seminaturalhabitats as well as contributing to regional nitrogen deposition. In the Netherlands effectshave been found close to poultry units (e.g. Berendse, Lurijsen and Okkerman 1988). Sutton, Pitcairnand Fowler (1993) found that 60-80% of total nitrogen inputs may be due to ammonia emissions,largely from agricultural sources.Intensive livestock (pig and poultry) units over a certain size have been required to apply to theEnvironment Agency for a Pollution, Prevention and Control (PPC) permit, within the framework ofthe Environmental Permitting Regulations. Natural England is a statutory consultee in this process. Anumber of pig and poultry units are located close to nature conservation sites, including SSSIs andSACs. An assessment of the likely impact on SSSIs/SACs of existing pig and poultry units has recentlybeen carried out by the Environment Agency as part of its PPC licencing process. Investigation as towhether evidence of site condition is indicative of damage from nitrogen deposition from thesesources to SSSI heathland sites in Breckland is being examined by the Natural England’s EvidenceTeam and the Norfolk & Suffolk Area Team.99
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Securing Biodiversityin BrecklandGu
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Commissioning GroupNeil Featherston
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Wind-blown sand guild .............
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milder winters and increased winter
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Creating broad ruderal and disturbe
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Introduction“Few of the lowland d
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Inland DunesThe 1km wide dune and b
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Following the Black Death of the mi
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The area of grass-heath declined by
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PingosPingos are ground water fed p
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Breckland Conservation and the Need
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SSSI. The Breckland Forest SSSI cit
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The Breckland Biodiversity Audit ha
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The Breckland bio-geographic region
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polygons of alternating calcareous
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quality calcareous fen communities
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Figure 2. The extent of Breckland,
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Table 3. Grass-heath vegetation in
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The Conservation Resource: Designat
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All other SSSIs are less than 600 h
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GrasslandHeathWoodlandWetlandFlowin
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Calcicolous grasslandsShingle, stra
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Figure 4. Location of designated si
Page 47 and 48: Figure 6. Location of Plantlife’s
Page 49 and 50: Figure 7. Locations of stations in
Page 51 and 52: Scheme for Stilt & Stalk Flies, Dra
Page 53 and 54: Table 6. Rare vascular plant specie
Page 55 and 56: Recommendation BTO be commissioned
Page 57 and 58: Table 7. Species for which records
Page 59 and 60: Table 8. Descriptions of Red Data B
Page 61 and 62: If the sub-species was designated b
Page 63 and 64: Collating and Synthesising Species
Page 65 and 66: Table 11. Published, documentary an
Page 67 and 68: Baron de Worms, C.G.M. (1953) Colle
Page 69 and 70: Guild AnalysisA number of habitat a
Page 71 and 72: The specific questions for the work
Page 73 and 74: Findings of the Breckland Biodivers
Page 75 and 76: Recording Effort and CoverageThere
Page 77 and 78: Butterfly Conservation (Suffolk) 17
Page 79 and 80: Norfolk Biodiversity InformationSer
Page 81 and 82: Figure 11. Number of taxonomic grou
Page 83 and 84: difference is partly attributable t
Page 85 and 86: There were Breckland specialist spe
Page 87 and 88: Figure 13. Proportion of Breckland
Page 89 and 90: Distribution of Breckland Conservat
Page 91 and 92: Figure 15. Number of Breckland cons
Page 93 and 94: Evidence of Climatic Change: Long-T
Page 95 and 96: Figure 17. Total seasonal precipita
Page 97: Biodiversity Implications of the Ch
Page 101 and 102: the status of Deschampsia flexuosa.
Page 103 and 104: The relative effects of ploughing,
Page 105 and 106: Trends in Species Status: Extinctio
Page 107 and 108: HymenopteraHymenopteraHymenopteraCo
Page 109 and 110: In addition to the loss of rare lic
Page 111 and 112: edstraw Galium parisiense (Tansley
Page 113 and 114: The relative extent of lichen rich
Page 115 and 116: The Feasibility and Usefulness of t
Page 117 and 118: Across patch arrangementLandscape c
Page 119 and 120: Across patcharrangementJuxtapositio
Page 121 and 122: Delivery of Multiple Species by Int
Page 125 and 126: Mechanical disturbance to create br
Page 129 and 130: estricted to road verges, with the
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Page 133 and 134: Records of species from this guild
Page 135 and 136: © Jeremy Earlywww.natureconservati
Page 139 and 140: Open with sward mosaics guildChryso
Page 141 and 142: Grazing without physical disturbanc
Page 143 and 144: Deadwood in an open-woodland ecoton
Page 145 and 146: Specific Requirement in a Variety o
Page 147 and 148: Management to Sustain Dry Terrestri
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Heather should rather be considered
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GrazingrequirementsLightly sheep-gr
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a mosaic of overlapping ploughed, a
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Wind-blown sandThere is great uncer
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IntensityProcess Technique Immediat
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Complex Sward MosaicsComplex sward
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Management for Assemblages of Light
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Management for Species of Physicall
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Key Recommendations for Cultivated
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Shallow cultivation is preferable t
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Maidscross Hill is largely overgrow
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Ecological Requirements of Wetland
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numbers of conservation priority sp
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Recommendation Requirements of wetl
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Figure 31. Number of Breckland cons
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Restored pingo complexAt Great Hock
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Figure 32. Number of Breckland cons
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the difficulties of achieving this
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Strategic Challenges to Biodiversit
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Table 22. Problems arising from poo
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Recommendation: Natural England and
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It is therefore vital to carefully
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Creating networks for resilienceTo
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More ambitious possibilities that c
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Figure 34. Example of a potential c
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Connectivity networks© Neal Armour
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and consider whether these repeated
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Ensure that scrub removal, ploughin
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ReferencesADAS. (1997) Biological M
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Haes, E. C. M. & Harding, P. T. (19
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Sastre, B.(2003). Ground spider com
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Securing Biodiversity in Breckland - European Commission

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