Fen Management Handbook - Scottish Natural Heritage

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Management neglect Hydroseral succession (secondary colonisation), either because of the cessation of management or because of a major environmental change, is often a threat to fen bryophytes, and fen managers need to consider whether natural succession is beneficial to their site or not. For example, the boreal relic rich-fen moss Tomentypnum nitens has now been lost to scrub encroachment or vascular plant growth from at least 3 of its 10 Welsh sites (K. Birch, pers. comm.). On the other hand, localised natural succession may enhance a site, perhaps leading to the reinstatement of ombrotrophic conditions in areas from which they were lost because of past management, but can lead to acidification of areas of rich-fen and consequent loss of specialist bryophytes. Crymlyn Bog in south Wales has experienced multiple successions from fen to raised bog (Hughes & Dumayne-Peaty, 2002), and a vegetation survey in 2009 suggests that part of the east side of this 280 ha complex of fen and swamp is experiencing the start of another succession. Not only is scrub encroaching rapidly, but four species of Sphagnum are locally abundant in communities dominated by Carex paniculata, Phragmites australis, Typha angustifolia and T. latifolia – combinations not recognised by, for example, Wheeler (1980). The bryophytes being replaced here are either those of neutral fen or rich-fen. This change in species composition can enrich a local flora, for example the arrival of at least six species of Sphagnum at Wicken Fen, Cambridgeshire (Preston, 2008) after years of scrub encroachment, reduced winter flooding and, probably, acid rain. A recent focus on maintaining/restoring open fen at Wicken, with consequent scrub clearance, pony grazing and raising of (calcareous) water levels, has caused the loss of several sphagna from their only Cambridgeshire site. Meanwhile, rich-fen mosses such as Campyliadelphus elodes were seen in 2008 for the first time since the 1950s. As always, fen management can have negative impacts as well as positive ones. The alternative would be to allow a complete transition to carr, which might benefit some bryophytes but would undoubtedly cause the loss of other rare species. There is no evidence that the epiphyte flora of British carr is particularly notable, despite its often very high bryophyte biomass, so scrub clearance on fen sites is likely to be of concern only if the ground flora is of note. Soligenous mires Soligenous fens are home to the UKBAP liverworts Barbilophozia kunzeana and Jamesoniella undulifolia, both of which grow in small quantity through base-tolerant sphagna at a handful of sites, for example on the Long Mynd in Shropshire. The scarce temperate form of Hamatocaulis vernicosus (Hedenäs & Eldenäs, 2007) is also found primarily in soligenous mires on the upland edge in Wales (Bosanquet et al., 2006) and to a lesser extent in England, Scotland and Ireland. A constant supply of neutral, nutrient-poor water is the main requirement of these species, so management that alters a site’s hydrology could have a negative impact on them. The hydrology of sites with H. vernicosus is often rather complex: several of its sites in south Wales are in areas where highly calcareous water derived from Carboniferous Limestone over 1 km away spreads on to, or bubbles up through, a peatland, which reduces the pH and provides suitable conditions for Hamatocaulis. Quarrying or water abstraction some distance from a flush complex can significantly alter its hydrology. Reduced grazing is currently threatening Hamatocaulis on upland-edge commons in Wales, perhaps exacerbated by vigorous vegetation growth because of atmospheric N deposition, and continued light to moderate grazing is necessary to maintain open swards suitable for the notable bryophytes to grow. Concluding remarks It needs to be emphasised that our knowledge of the distribution of fen bryophytes remains remarkably patchy. Paludella squarrosa was discovered new to Ireland in 1998 (Lockhart, 1999), Scorpidium turgescens new to England in 2002 (Porley & Hodgetts, 2005), Leiocolea rutheana new to Scotland in 2001 (Blackstock, 2002), Sphagnum riparium new to Wales in 2005 (Jones et al., 2006) and more than five new sites for Jamesoniella undulifolia have been found in Cumbria and Shropshire in the last few years. Because of this, it is vital that managers of rich-fens and transition mires get a competent bryologist to survey their site before any dramatic changes in management or hydrology. Translocation experiments by Malson & Rydin (2007) suggest that it is possible to reintroduce at least some bryophyte species to restored rich-fens using gametophyte fragments as propagules. 301
However, three of the four species involved (Campylium stellatum, Scorpidium cossonii and S. scorpioides) are among the commonest rich-fen mosses and continue to thrive in upland flushes, only Pseudocalliergon trifarium has shown a significant decline in lowland Britain, and their experiments did not look at more specialised rich-fen plants, such as Paludella squarrosa, Tomentypnum nitens or Leiocolea rutheana. They recommended surface liming of exposed peat and the use of protective covers over the moss fragments. Maintaining water levels suitable for growth is critical, as Malson & Rydin found significant differences in growth with just 5 cm changes in water depth. In general, management undertaken for fen habitat or vegetation features is likely to be broadly beneficial for fen bryophytes. The majority require reasonably open conditions maintained by seasonal grazing and/or rotational mowing. Irrigation by water poor in macro-nutrients and of variable base status (depending on the character of the fen feature) is essential, and most species require perennially high water tables, with some benefiting from periodic inundation. References Bergamini, A., Peintinger, M., Fakheran, S., Moradi, H., Schmid, B. & Joshi, J. 2009. Loss of habitat specialists despite conservation management in fen remnants 1995-2006. Perspectives in Plant Ecology, Evolution and Systematics 11: pp. 65-79. Blackstock T.H. 2002. New Vice-County records and amendments to the Census Catalogue. Bulletin of the British Bryological Society 79, p. 39. Bosanquet, S.D.S., Hale, A.D., Motley, G.S. & Woods, R.G. 2006. Recent work on Hamatocaulis vernicosus in Mid and South Wales. Field Bryology 90, pp. 2-8. Church, J.M., Hodgetts, N.G., Preston, C.D. & Stewart, N.F. 2001. British Red Data Books, mosses and liverworts. JNCC, Peterborough. Hedenäs, L. & Eldenäs, P. 2007. Cryptic speciation, habitat differentiation, and geography in Hamatocaulis vernicosus (Calliergonaceae, Bryophyta). Pl. Syst. Evol. 268, pp. 131-145. Hughes, P.D.M. & Dumayne-Peaty, L. 2002. Testing theories of mire development using multiple successions at Crymlyn Bog, West Glamorgan, South Wales, UK. Journal of Ecology 90, pp. 456-471. Jones, P.S., Turner, A.J., Bosanquet, S.D.S. & Blackstock, T.H. 2006. Sphagnum riparium discovered in Wales. Field Bryology 89, pp. 2-3. Limpens, J., Tomassen, H.B.M. & Berendse, F. 2003. Expansion of Sphagnum fallax in bogs: striking the balance between N and P availability. Journal of Bryology 25, pp. 83-90. Lockhart, N.D. 1999. Paludella squarrosa (Hedw.) Brid., a boreal relic moss new to Ireland. Journal of Bryology 21, pp. 305-308. Malson, K. & Rydin, H. 2007. The regeneration capabilities of bryophytes for rich-fen restoration. Biological Conservation 135, pp. 435-442. Malson, K. & Rydin, H. 2009. Competitive hierarchy, but no competitive exclusions in experiments with rich-fen bryophytes. Journal of Bryology 31, pp. 41-45. Porley, R.D. & Hodgetts, N.G. 2005. New Naturalist: Mosses and Liverworts. Collins. Preston, C.D. 2008. British Bryological Society Cambridgeshire Group excursions 2007-2008. Unpublished report. Swann, E.L. 1982. Norfolk bryophytes today. Journal of Bryology 12, pp. 77-112. Wheeler, B.D. 1980. Plant communities of rich-fen systems in England and Wales. Journal of Ecology 68, pp. 365-395. Van Wirdum, G. 1995. The regeneration of Fens in Abandoned Peat Pits Below Sea Level in the Netherlands. In Wheeler, B.D., Shaw, S.C., Fojt, W.J. & Robertson, R.A. 1995. 302
Page 1 and 2:
The Fen Management Handbook Edited
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Acknowledgements Production of the
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1. Introduction and Basic Principle
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Estimates of the original coverage
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Guiding principles for fen manageme
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Section 12: Fens from an Economic P
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2.1 Diversity and conservation sign
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Part of Cropple How Mire in Cumbria
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The moss flora of base-rich springs
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Bog bean growing in a transitional
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Mesotrophic openwater transition fe
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Water shrews (Neomys fodiens), also
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2.4.1 Vegetated margins of open wat
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2.4.3 Grazed or cut fen in floodpla
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2.6 Amphibians Amphibians are depen
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The mud snail Omphiscola glabra (12
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Old trees and dead wood Continuous
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Vascular plants Flat-sedge Blysmus
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3. Understanding Fen Hydrology Quan
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Groundwater discharge to fens is us
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Water Table 3.4.1.4 Spring fed fen
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3.5 Factors determining fen type 3.
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- Flooding - frequency and magnitud
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3.7 Further information and advice
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Groundwater inflow. Groundwater lev
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It is likely that groundwater disch
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Case Study 3.3 Hydro(geo)logical im
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4. Understanding Fen Nutrients Nutr
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nutrients. For example, at high con
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4.2.1 Groundwater and surface water
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4.2.3 Point and diffuse sources of
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Area of acute nutrient enrichment o
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4.4 Classifying water chemistry usi
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4.6 Identifying nutrient enrichment
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Negative indicator species for diff
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Many of the floristic changes which
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Case Study 4.1 Understanding Fen Nu
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5.1 Why do fens need management? In
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5.2 Checklist of key stages in deci
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5.3.3 Scale Although fens are linke
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5.4 Site survey to establish what i
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variability and how these relate to
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- The fauna which inhabit the fen c
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- Prioritise objectives to achieve
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inundation are less likely to be sp
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5.13 References Barsoum, N., Anders
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Case Study 5.2 Fen Management and R
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- 14km of livestock fencing install
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Case Study 5.3 Fen Management and R
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6. Fen Management and Restoration -
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Both the benefits and potentially l
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Cattle forced by flooding to the ed
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At low/medium stocking density, cat
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Goats have narrow muzzles and a fle
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Fens usually feature a range of dif
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Excessive poaching where cattle hav
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extensive areas of wetlands which w
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‘Soft track’ machines, such as
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The design of the pipeline allows f
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Protocol for burning standing reedb
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Long rotation scrub clearance may b
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‘Bird-eye’ and incineration A t
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6.7 Restoring fen meadow Many forme
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Current Management The current mana
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Case Study 6.2 Fen Vegetation Manag
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species diversity of wetland passer
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The temptation to burn large areas
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Outcomes In the eight years that th
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Anglesey sites is now underway supp
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Close grazed short sward of sedges
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Turf cutting Turf cutting has been
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7.1 A framework to assist decision
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Surface water level change e.g. - a
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and the surface to acidify, resulti
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Smaller excavations are preferable
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Morton Lochs, which extend to appro
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Although shallow excavations are pr
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At Leighton Moss in Lancashire, are
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Excavating spoil within the area to
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uilt dams can only be formed in dit
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Case Study 7.1 Fen Water Management
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8. Managing Fen Nutrient Enrichment
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Summary table of key techniques for
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8.2 Managing the source of nutrient
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Marginal interceptor ditch at Cors
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8.3.4 Bund creation In some cases i
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emoval or soil stripping, both of w
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8.5 Monitoring nutrient reduction D
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Recent photo of stripped surface sh
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9.1 Scope for fen creation The Grea
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9.3 What type of fen? New fens can
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9.5 Restraints on fen creation Plan
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9.6 Check list of issues to conside
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9.7 Site assessment Planning and de
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LIDAR maps can provide a general un
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generally more acidic than silts an
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Site visits and careful assessment
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9.8.4 Plastic membranes On sites wi
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Use of seed bombs ‘Seed bombs’
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Experience has shown that the most
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9.10.2 Creation of niches for plant
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Meade, R. & Wheeler, B.D. 2007. Rai
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- On-going measurement of the effec
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with appropriate training. Providin
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10.3 Biological monitoring techniqu
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Undesirable species for key NVC com
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10.3.3 Vegetation Mapping An initia
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It is good practise to record with
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10.4 Biological monitoring techniqu
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for Ornithology, the Bat Conservati
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Box 2: Construction, installation a
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10.8 Monitoring surface water flows
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- Phytometric tests measure how wel
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Storage of data and information on
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period, simply because it is design
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Another consideration is the likely
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11.1 An historical perspective Poll
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Inviting volunteer involvement in f
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11.3.3 Stakeholders ‘Stakeholders
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have been designated under access a
Page 247 and 248: 11.6.4 Boardwalks Boardwalks are no
Page 249 and 250: 11.6.5 Water borne access Waterways
Page 251 and 252: - Explore opportunities to stimulat
Page 253 and 254: Case Study 11.1 Fens and people - S
Page 255 and 256: Case Study 11.2 Fens and People - H
Page 257 and 258: 12. Fens from an Economic Perspecti
Page 259 and 260: 12.1.3 Biomass energy and Biofuels
Page 261 and 262: 12.2 Environmental regulation 12.2.
Page 263 and 264: the peat carbon store is depleted t
Page 265 and 266: Another mechanism for funding wetla
Page 267 and 268: Whitlaw Mosses in Scotland (see det
Page 269 and 270: 12.8 References Dickie, I., Hughes,
Page 271 and 272: Nitrogen fixation conversion of gas
Page 273 and 274: Appendix III - List of species refe
Page 275 and 276: Table 1 - Mammal species associated
Page 277 and 278: 280 Bittern Botaurus stellaris All
Page 279 and 280: Grasshopper Warbler 282 Locustella
Page 281 and 282: Table 4 - Fish species associated w
Page 283 and 284: Table 5 - Legally protected inverte
Page 285 and 286: 288 Community Topogenous fens S24 P
Page 287 and 288: 290 Community S8 Scirpus lacustris
Page 289 and 290: 292 Community M11 Carex demissa - S
Page 291 and 292: 294 Community M23 Juncus effusus /
Page 293 and 294: Appendix V - Legal and regulatory c
Page 295 and 296: 298 Type of Works Guidance for UK C
Page 297: Appendix VI - Fen management for br
Page 301 and 302: Sensitive periods Harvest mice bree
Page 303 and 304: species like bittern, and then drop
Page 305 and 306: Sensitive periods Species breed wit
Page 307 and 308: Great Crested Newt Great crested ne
Page 309 and 310: Appendix VIII - Fen management for
Page 311 and 312: Mollusca (snails, slugs and mussels
Page 313 and 314: Other than for rare or exceptional
Page 315 and 316: There is usually some degree of sub
Page 317 and 318: Management requirements for protect
Page 319 and 320: Appendix IX - Further reading Secti
Page 321 and 322: Koerselman, W., Bakker, S.A. & Blom
Page 323 and 324: Section 5: Fen Management and Resto
Page 325 and 326: Patzelt, A, Wild, U. and Jörg Pfad
Page 327 and 328: Index A access 103, 110, 190, 226,
Page 329: cutting 114 disposal 117 management
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Fen Management Handbook - Scottish Natural Heritage

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