Description:
A method developed in Italy to assess deviation from natural lichen diversity on trees in sites within a homogeneous bioclimatic area. LD is calculated using the sum of frequencies on trees of the same species within 10 samples of units 15 cm x 10 cm (30 cm x 50 cm) and the mean calculated from the number of relevees. A 5-scale class of deviation from naturality is based on % deviation from the natural LD values in the area and can be correlated with climatic, land management and pollution data. Loppi et al. (2003)
Previous experience:
The method was developed and applied in the Tyrrhenian area of Italy using Tilia and deciduous Quercus. LD calculated for each phorophyte and a scale of deviation from naturality was worked out for both phorophyte species (Loppi et al. 2002).
Field work in this report (Pitcairn et al. 2003) suggests that on comparison with a local conservation site a woodland near an ammonia source showed a loss of diversity even for the cleanest location at 300 m from the farm.
Suitability to indicate atmospheric concentrations:
Uncertain, but not well suited as the relationship with total lichen diversity is complex. Not well suited.
Suitability to indicate atmospheric depositions:
Uncertain, but not well suited as the relationship with total lichen diversity is complex.
Suitability to indicate environmental impacts:
Changes in lichen diversity by definition represent an indication of nitrogen impacts, but methods based on lichen diversity alone unlikely to be suitable for assessing impacts of N due to the complex relationship to N levels.
Sensitivity to other factors:
Climate change and temperature may cause shifts in lichen communities towards nitrogen tolerant species. The lichen flora of tree species depends different characteristic bark types.
Timescale:
Lichen biodiversity on tree trunks represents a consequence of the previous pollution climate over several decades. A 3-5 year time period between surveys is recommended.
Limitations:
Requires a sufficient number of trees of a single species in a relatively homogeneous environment.
Expertise in field:
Specialist/trained personnel are needed for lichen identification
Expertise in laboratory:
Limited chemical analysis of specimens is required for the identification of species. Analysis of data only requires the application of an equation to calculate deviation from naturality.
Cost (per unit sample): £unknown
Cost Comment: Not well established at present. Indicatively, it may take c. 2 days of external specialist time to locate suitable trees and record releves on c. 5 trees. A total cost needs to account for travel and data analysis time of external specialists.
Robustness: 
