Evaluation of habitats for nature conservation

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Evaluation of habitats for nature conservation

• To a greater extent than ever before, habitats
  and species are threatened.
• Conservation will increasingly be required and
  involve
• - designation of sites for various degrees of
  protection
• - implementation of management plans
• How do you select a site for conservation?
• Not all habitats can be conserved, and some
  habitats can be afforded greater priority for
  conservation than others.
• This lecture introduces a number of important
  criteria that are used in assessing the
  conservation value of a site.

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Anglesey is a large (72,000 ha) island off the
north coast of Wales

• Lakes and reedbeds
• support the greatest number of breeding wildfowl
  in Wales
• lime-rich fens are unique in Wales
• wildlife and plant communities rare or absent
  elsewhere in Wales
• Wet pastures scattered across the farmland still
  provide food and breeding sites for wading birds.

3
Cors Erddreiniog 289-hectare SSSI, includes a
190-hectare National Nature Reserve and is the
largest fen in Wales. Black bog rush Schoenus
nigricans Blunt flowered rush, Juncus
subnodulosus Great fen sedge Cladium mariscus
Fly orchid Ophrys insectifera Marsh gentian
Gentiana pneumonanthe, Southern damselfly
Coenagrion mercuriale at its most northerly
location
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Llyn Rhos-dduThis shallow lake is dammed by the
Newborough Warren sand dune system and is part of
that National Nature Reserve. The lake supports a
good range of aquatic plants and animals
including mare's-tail Hippuris vulgaris. Water
level was accidentally lowered about 0.6 metres
some years ago. The AWS group has helped to
install a sluice, being used to restore the water
level.
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Snowdonia
Purple saxifrage Saxifraga oppositifolia
Snowdon lily Lloydia serotina
Chough
Rainbow beetle
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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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A word of caution...

• These criteria are not definitive
• they are not strictly independent, or all
  necessary for consideration all of the time
• they are not entirely objective
• there are frequent exceptions

• HOWEVER
• they are intended to stimulate a comprehensive
  evaluation
• they provide a structured evaluation process
• they are widely and, with experience, reliably
  used

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Size

• landscape suffers from severe fragmentation of
  natural habitat
• A general ecological rule is that larger habitats
  contain proportionally more species than smaller
  habitats
• species population sizes tend to be larger in
  larger habitats
• But size isnt everything!
• Small areas may be of high quality/very rare
  habitat
• a small habitat may have a high proportion of the
  local, national, or international population of a
  species

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Diversity

• Physical, habitat, species and community
  diversity
• Usually, higher diversity is better
• e.g. calcareous grasslands gt50 species m-2
• improved grassland 2 species m-2
• However, diversity can be high, but of poor
  conservation value
• Diversity is related to a number of different
  processes, and need to identify such processes
  that are important at a site

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Naturalness

• More natural implies
• of greater conservation value
• absence of human interference (relative!)
• a natural habitat can change over time
  (succession, env. conditions)
• Need to consider
• presence of introduced species
• how the habitat differs from other less disturbed
  habitats
• can the habitat be maintained/improved
• is another species dependent on it
• Greenland whitefront goose favours grazing on
  improved grassland, the latter being of low
  intrinsic conservation value

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Rarity

• Establish the wider distribution of a rare
  species/habitat
• local, regional, national, international?
• Why is it rare?
• Limit of geographical distribution
• relict populations (e.g. Arctic alpine flora)
• specialised local requirements
• Is it likely to continue to survive? (long-term
  viability)

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Fragility

• the degree of sensitivity of habitats,
  communities, and species to environmental change,
  and so involves a combination of intrinsic and
  extrinsic features (Ratcliffe 1977)
• Succession natural dynamics of vegetation
  turnover
• Anthropogenic disturbances
• how serious is the disturbance? (extent of
  damage)
• how likely is recovery?
• Underlying causes of fragility?
• Viability?
• Within what timescale?

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Typicalness

• Sites can be selected and valued because tjhey
  represent the best example of a particular
  habitat (which may not be threatened).
• What is the typical landform/habitat/community
  for an area?
• what are the typical species for a
  habitat/community?

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Recorded historyPosition in ecological unit

• Habitat value may be enhanced if their history
  and management is known, for the management of
  one site, and understanding of others.
• Availability and quality of scientific and land
  use records
• availability of accessible natural evidence
• pollen record in peat bogs
• relevance of records to value of the features
• Position in ecological unit
• most obvious example is offshore island
• reflects isolation, fragmentation, size of unit,
  buffer area, quality of buffer area, land use
  around habitat

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Potential for improvement/restoration

• Reflects isolation, fragmentation, size of unit,
  buffer area, quality of buffer area, land use
  around habitat
• Habitats are usually imperfect
• Need to assess the potential for improvement
• can there be total recovery?
• Will partial recovery be adequate?
• e.g. removal of weeds, Rhododendron
• removal of exotic predators

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What features make a site of conservation value?

• Size
• Diversity
• Naturalness
• Rarity
• Fragility
• Typicalness
• Recorded history
• Position in ecological unit
• Potential for improvement/restoration

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Summary

• 639.9-SPE. Evaluation and assessment for
  conservation ecological guidelines for
  determining priorities for nature conservation.
  Spellerberg Ian F.
• Goldsmith. Monitoring for conservation and
  ecology.