One of the principal aims of Pantheon is to help assess sample quality for nature conservation purposes. Absolute certainty over site quality cannot be properly resolved without a systematic and comparable survey of all sites throughout England. As one is not forthcoming in the foreseeable future, caution should be applied when interpreting results. Despite this, evaluation is possible with high quality survey data and site inventories, and, in particular, if there is comparable data from other sites to hand.
It should also be noted that:
- a long species list may indicate a rich site or a well-worked site; just because a site has a long list does not necessarily mean it is a rich site;
- representation across taxonomic groups in biotopes, habitats and their nested resources is very variable (e.g. a list of moths sampled from a wetland will show a very different output from a list of beetles). Care should be taken with samples consisting of limited taxonomic groups;
- a list with a high proportion of rare species may indicate a site that supports an unusually high proportion of rare species (a high quality site) or a site that is quite average but has been well-worked or a site where nobody has made much effort to record the common species;
- a site may be important for invertebrates by virtue of a single rare species with a very restricted distribution (e.g. Tadpole Shrimp, New Forest Burnet) though it may appear not to be a high quality site if looking at measures such as species richness, Species Quality Indices, or number of species with a conservation status.
The scoring systems below make use of species richness, threat status, rarity and characteristic species for each broad biotope, habitat and resource.
More work is required to refine these scores and produce benchmarks and site ranking. The four current scoring systems are described below.
1. Count – the number of species within each category
This is the simplest of all the scores. Low counts may mean that SQI scores (see section 4 below) are not reliable. High counts can be used to assign quality based purely on species richness.
2. Conservation Status – threat and rarity status from published reviews
The conservation status of species is complicated by the fact that there are two different systems in place – an ‘old’ system, that combines both threat and rarity, and a ‘new’ system that separates these. New reviews replace the old conservation status. The conservation status is also used to generate the Species Quality Indices (see section 4 below).
Sample quality can simply be derived from the overall number of species with a conservation status, and the number of species within each type of status.
Please note - some statuses are reported in square brackets. This is to indicate that these are considered out of date and should be used with caution.
The ‘New’ system is a two-pronged approach that separates rarity from threat. Threat is calculated using internationally recognised post-2001 IUCN criteria:
- EX - Extinct
- RE - Regionally Extinct
- CR - Critically Endangered
- CR(PE) - Critically Endangered (Possibly Extinct)
- EN - Endangered
- VU - Vulnerable
- NT - Near Threatened
- DD - Data Deficient
- LC - Least Concern
- NA - Not Assessed
- NE - Not Evaluated
The spiders and micro-moths are marked with a p before the status, to indicate that these are provisional statuses.
Two groups of flies (Empidoidea and some Nematocera and Aschiza) were assessed using post-1994 IUCN criteria. The abbreviations for these are in brackets.
Rarity is calculated using the Great Britain Rarity Status:
- Nationally Rare - Those which have been recorded from between 1-15 British hectads (10 km x 10 km squares) within a given date class where there is reasonable confidence that exhaustive recording would not find them in more hectads.
- Nationally Scarce - Those which have been recorded from between 16-100 hectads within a given date class where there is reasonable confidence that exhaustive recording would not find them in more hectads.
Species can have a status in both the threat and rarity categories above (e.g. Carabus intricatus is both Near Threatened and Nationally rare).
The ‘old’ system - species having been evaluated using the pre-1994 criteria:
- Extinct - Listed as RDB App or Extinct
- RDB 1 - Endangered
- RDB 2 - Vulnerable
- RDB 3 - Rare
- RDB K - Insufficiently Known
- RDB I - Indeterminate
- Na - Notable A
- Nb - Notable B
- Notable - Notable or Nationally Scarce
- NR (marine) - Nationally Rare (marine species)
- NS (marine) - Nationally Scarce (marine species)
- Unknown - A few micromoths are listed as status Unknown
- None - Not rare or scarce
- Not reviewed - The taxon was not assessed for rarity in the review
- New to Britain - Recently added to the British list and not yet reviewed, but it is still rare as far as we know
- Not native - The taxon is thought not to be native
3. % representation (Percentage Representation)
For any given broad biotope, habitat or resource, % rep is calculated by:
- the number of species in that resource in the sample / the total number of species in that resource in the Pantheon database
E.g. if sample X had 30 saltmarsh species and Pantheon has 302 saltmarsh species in total, then the % representation = 30/302 = 10%.
High scores suggest that the sample includes a high proportion of characteristic species, which can be an indicator of quality. Scores of between 10-20% may indicate good quality; scores of 21%+ certainly suggest a good proportion of characteristic species. Caution should be applied when the total number of species coded to any given category is low (10 or less) or are coded to categories that do not necessarily indicate quality (e.g. ubiquitous, synanthropic).
4. SQI - Species Quality Indices
Quality indicators such as this have been used in the past on a number of assemblages (dead wood and riparian). Each species recorded from the sample are given a Species Quality Score (SQS) based on their conservation status (see table below). However, where there is robust recent information to show that the official status is no longer appropriate, the SQS assigns a rare or scarce status using the more recent information (see note below table). The source of this information is given in the Source of Rarity column.
The SQI is equal to the sum of all SQSs in any given resource, divided by the number of species. This score will then be multiplied by 100 to give a 3 figure value without decimal places (e.g.100 rather than a 1.00).
Any SQI score derived from a small number of species should be treated with caution. It is suggested that scores derived from 15 or less species should not be used.
- In older reviews, species not classed as RDB - App, RDB 1-3, or notable. Includes RDB - Endemic unless included under another criterion.
- This includes Nationally Scarce species that do not qualify under any of the other criteria. They may be classed as IUCN Least Concern, Near Threatened, or Data Deficient, Not Evaluated, or Not Assessed. In older reviews, species classed as Notable, Notable A, Notable B, Scarce, RDB I and RDB K.
- This includes Nationally Rare species that do not qualify under any of the other criteria. They may be classed as IUCN Least Concern, Near Threatened, or Data Deficient, Not Evaluated, or Not Assessed. In older reviews, species classed as RDB 3
- In older reviews, species classed as RDB 2
- In older reviews, species classed as RDB 1.
Two groups use rare and scarce lists that did not assign threat. These are the solitary aculeates and the macro-moths:
- The solitary aculeates use Michael Archer's statuses (Archer, M.E. 2014. Archer's status values for the solitary wasps and bees. BWARS Newsletter Autumn 2014: 32-37; Archer, M.E. 2015 Changes to Archer's solitary wasp and bee species statuses after consulting the NBN database. BWARS Newsletter Autumn 2015: 26-27). His Scarce (31-100 hectads) and Rare (16-30 hectads) species score 4 because they are equivalent to nationally scarce; his Very rare species (1-15 hectads) are equivalent to nationally rare, so they score 8 unless they were also listed as RDB 1 in the status review, in which case they score 16. His Restricted, Widespread, and Universal species (all from more than 100 hectads) score 1.
- The macro-moths scores are from the Field guide to moths of Great Britain and Ireland (Waring, P., Townsend, M., and Lewington, R. 2003. Field guide to the moths of Great Britain and Ireland. Hook: British Wildlife Publishing). The Na and Nb species score 4. RDB species score 8 unless they were also listed as RDB 1 in the Insect Red Data Book, in which case they score 16. Other species score 1.