1. Enter a site location as a standard 10km grid-reference (i.e. letters/numbers).
2. Selecting the ‘Baseline’ environmental scenario allows a comparison of lichen species environmental suitability (envS) determined by ‘present-day’ climate, pollution, and woodland landscape values (extent of ancient woodland), with those of future scenarios. Baseline scenarios can be modified by incorporating user defined tree composition.
3. Select up to two contrasting future scenarios to compare with the baseline. These future scenarios could be the baseline environment with a different woodland composition, or a choice of two contrasting climate change scenarios: a 2050s medium greenhouse gas emissions pathway (2050M), and a 2080s high greenhouse gas emissions pathway (2080H), each implemented with lowered SO2 pollution.
4. ‘Select All’ lichen species for a generic evaluation of environmental and/or tree composition scenarios on environmental suitability (envS) for lichen epiphytes.
5. Alternatively, scroll, or use the search and sort functions to select lichen species of interest.
6. Species nomenclature mostly follows the British Lichen Flora by Smith et al. (2009), with some recent exceptions, e.g. Mycoblastus fucatus = Violella fucata. If in doubt, consult the British Lichen Society Taxon Dictionary.
7. If chosen as an option, tree species composition at the baseline and for any scenarios may now be selected.
8. Choices made here modify the value of environmental suitability (envS) that is based on the larger-scale environment (climate, pollution, and ancient woodland extent) by using a simple correction that accounts for tree species composition in a woodland stand: Corrected envS = envS * [(Pri * Tfi/5) + (Prj * Tfj/5)… ] [Eq. 1]
9. Where Pr is the proportion of records for an epiphyte species associated with a given tree (i, j, ...), and Tf is the frequency of a given tree species (i, j, ...) within a woodland stand calculated on a 5-point scale that is analogous to scores used in UK’s National Vegetation Classification.
10. Values for trees between 1 and 5 are equivalent to the upper bounds of frequency classes (or ‘constancy’) within the NVC. Considering a series of plots within a stand, the occurrence of a given tree species is estimated in five classes: up to 20% of plots (1, or a proportion/weighting factor of ‘0.2’), 21-40% (2, or ‘0.4’), 41-60% (3, or ‘0.6’), 61-80% (4, or ‘0.8’), or in 81-100% of plots (5, or ‘1’).
11. The results page can be printed out, and provides for each species:
12. Species can be sorted alphabetically, or by their properties (conservation status).
13. The Bray-Curtis metric (Krebs 1999) is used to describe the overall community-level difference (dissimilarity) in envS compared among selected species, between the baseline and scenarios, from 0 (identical, or no change) to 1 (completely different).
14. Bray-Curtis is preferred to an averaged value of change across species, because in a two species community, if for example Sp. A transitions from an environmental suitability of 0.5→0 ( = -0.5) and Sp. B from 0→0.5 (= +0.5), the average degree of change is 0, though the actual dissimilarity is 1 (complete switch in community composition).
15. However, the interpretation of the Bray-Curtis metric should be combined with an understanding of the species values in environmental suitability (envS), because a community of two species which transition from envS values of 0.01→0 and 0.05→0, and from values of 0.9→0 and 0.95→0, would both score a change of 1, though the felt consequences of the shifted envS may be very different.