what to prioritise? sites (lecture 4) Flashcards
Why target sites?
- protected areas
- wider landscape conservation
- specific management
protected areas:
- Aichi protected area coverage aims by 2020: 17% land/freshwater & 10% marine
- 50% earth goal not viable bc many ecoregions have less than half of their natural habitat left
wider landscape conservation:
- e.g restoration, agri-environment schemes
specific management:
- e.g. invasive species control
need to select sites to maximise effectiveness
What are the two scales of prioritisation?
global scale
- selection of large regions of conservation value
- e.g. madagascar, 12,000 endemic species
- well defined prioritisation schemes
- but conflicting and not as robust as ideal
local scale
- which specific localities within these hotspots
- limited standardisation
- most rigorous is Ratcliff’s UK scheme
What are the nine prioritisation strategies on a global scale?
- crisis ecoregions (CE)
- centres of plant endemism (CPE)
- high biodiversity wilderness areas (HBWA)
- biodiversity hotspots (BH)
- megadiverse countries (MC)
- frontier forest (FF)
- endemic bird areas (EBA)
- global 200 ecoregions (G200)
- last of the wild (LW)
How is vulnerability used by global scale prioritisation strategies?
vulnerability can be in terms of:
- % habitat lost (assumes past lost predicts future loss)
- human population (ok indicator)
- protected area coverage (ok indicator)
- total forest cover (poor indicator)
- none use number of threatened species!!
Are low or high vulnerability sites more important to conserve?
Proactive prioritisation focuses on low vulnerability areas:
- frontier forests, last of the wild, high biodiversity wilderness areas
What are irreplaceability indicators?
- most common is endemism
- used by four strategies in terms of plants and one in terms of birds
- reasonably assumes strong relationship between endemism in different groups
Why don’t any irreplaceability indicators rely entirely species richness?
- incorporated into WWFs 200 ecoregions
- this is good bc common species less in need of conservation can determine species richness patterns
What influence has Ratcliffe (1977) A Nature Conservation review had?
- criteria have had major influence inside and outside of UK
- principles apply when selecting a site/group of sites
- critical assessment of criteria provides a good understanding of the key issues
What are Ratcliffe’s criteria?
- size
- diversity
- rarity
- naturalness
- fragility
- typicalness
- recorded history
- position in ecological/geographic unit
- potential value
- intrinsic appeal
DIDN’T factor in cost but should have
Why prioritise site size?
- larger site = more species
- species-area relationship
- non-linear, yields relatively little benefit after threshold level
- threshold varies b/w region/taxa
- larger sites = larger populations
- larger reserves = fewer edge effects
What are types of edge effects?
human activities extending into reserve areas:
- e.g. resource extraction, pesticide drift
animal movement outside of reserves
- animals w large home ranges more likely to move out of smaller protected areas
- wide-ranging carnivores suffer higher extinction risk in fixed-size reserves than those with smaller home ranges when accounting for population size (Woodroffe and Ginsburg, 1998)
Why prioritise site diversity?
- high habitat diversity promotes species richness
- many species need multiple habitat types e.g. altitudinal migrants and amphibians
Problems with prioritising site diversity?
- habitat diversity
- species diversity
- high habitat diversity is only good if all habitats are high quality
- high habitat diversity can reduce species diversity at small sites
- habitat specialists can’t maintain viable populations if each habitat type is tiny
- species richness too simple, depends on priorities
- area with 200 species but 1 endemic maybe less important than are with 100 species but ten endemics
Why prioritise rarity?
- rarity must be looked at along with long-term viability
- e.g. natterjack toad SSSI guidelines
- all established and important sites
- established = occupied for > 5 years
- important = higher populations than average (100 individuals or 25 spawn springs for two of the last 5 years)
- rarity vs threat
- in uk many species threatened with extinction
Why prioritise naturalness?
- areas least modified by humans should be prioritised
- difficult to quantify
- human modified areas can be valuable
Why prioritise fragility/threat?
- sites w more threatened species/habitats most worthy of protection
- IF threat can be countered by site-based protection
- not the case for many threats e.g. nitrogen, acid rain
Why prioritise typicalness?
- sites most characteristic of focal habitat are better
- set of indicator species are representative of habitat X
- compare ideal species set with those at site
- closer match = more typical
- is conserving the “average” a good aim?
Why prioritise recorded history?
- sites with long history of ecological research need protection
- e.g. whytham woods, oxford; barro colorado island, panama
Why prioritise position within an ecological or geographic unit?
- sites at edge of distributions may be of more value
- data on limiting conditions can inform management
- unique local adaptations
- facilitate range shifts in response to climate change
Why prioritise potential value?
need to consider if a sites value will increase in future
- e.g. through habitat restoration like at Lakenheath
climate change can increase or decrease site values in future (Hole et al., 2009)
- change habitat type
- focal species may move away
- new species may colonise
- most sites retain high (but different) value
value of site for education
Why prioritise intrinsic appeal?
- idea sites with charismatic taxa more important
- highly controversial and often considered wrong
- BUT if wishing to retail recreational ecosystem services may be correct
Beyond Ratcliffe’s criteria: why prioritise representation?
- focal species must be represented by at least one viable population in a protected site
- Ratcliffe assumed this would be the result if his criteria followed but not necessarily case
- 300 critically endangered vertebrates occur entirely outside protected areas globally
Beyond Ratcliffe’s criteria: why prioritise cost effectiveness?
- invasive species eradication
- e.g. invasive species eradication on islands
- 2 priority lists: conservation benefits / conservation benefits per unit cost
- totally different results
- 3 highest change
- only 13 islands in top 20 priorities on both list
- second list 2-7x more cost effective
Beyond Ratcliffe’s criteria: why prioritise cost effectiveness?
- australian nature reserves
- target 15% of each of 58 major habitats in protected areas
- benefit increases with cost, but massive variation
- replacing least effective 1% keeps costs identical but increases number of habitats meeting the target from 18 to 54
