Supplementary field manual, with recording forms, to be used in conjunction with the -based index guide for determining nitrogen air quality

This field manual includes: Lewis (2012) identified two functional groups: that are sensitive (N-sensitive) to increasing concentrations of • Two field recording forms (Site summary and lichen atmospheric N and those that are tolerant (N-tolerant). recording forms) that can be downloaded from http:// www.apis.ac.uk/guide-using-lichen-based-index-assess- Indicator lichens were selected from leafy, bushy and crustose nitrogen-air-quality lichen taxa growing on trunks and branches of oak and trees (see Figure 1) across Britain at sites where concentrations • Lichen recording form to be used in the field to score of atmospheric nitrogen were routinely measured or the presence or absence of lichens on branches and measured during one year of the study. Commonly occurring trunks. It lists the nine N-sensitive and eight N-tolerant lichen species were recorded and evaluated for their response lichen taxa. to different forms of atmospheric nitrogen, namely reduced • Worked example of the lichen recording form which N, dry deposited ammonia gas and oxides of nitrogen. This illustrates how a recording sheet should look if completed presence and absence data was used to select lichen taxa that according to instructions described in the guide. Separate were tolerant of, or sensitive to increasing concentrations of forms for recording trunks and branches are included. atmospheric nitrogen.

• Site summary form, which records site information and In the context of drawing up a lichen based index that reflects a summary of the LIS and NAQI scores. the concentration range of N pollutants present in the local atmosphere indicator lichens needed to be not only tolerant • Worked example, that can be used to summarise the or sensitive but also widely distributed and most importantly, recorded data on sensitive and tolerant lichens and easily identifiable, i.e. a sensitive lichen should not be record important site specific information e.g. grid ref/, readily confused with a tolerant lichen. On the basis of such altitude, overall impression of site vegetation health). characteristics the list of potential indicator lichens was reduced down to eight N tolerant and nine N sensitive indicators. • Short background synopsis of the research study by Jason Lewis in collaboration with CEH, The Natural History Identification of lichens Museum and the University of Nottingham (http:etheses. nottingham.ac.uk/3573) that identified, tested and Indicator lichens can be classified into 3 distinct types: bushy developed the N air quality index based on epiphytic lichens or fruticose lichens that are only attached to the substrate at growing on trunks and branches of oak and birch trees. the base; leafy or foliose lichens that are loosely attached by rootlet like structures called rhizines and crustose or granular • FAQs (Frequently asked questions) – which might arise lichens that resemble a skin that you cannot remove from during the field survey. the (Figures 1and 2). The fold-out hard copy Lichen Guide can be purchased from the FSC (http://www.field-studies-council.org/publications/ Indicator lichens pubs/guide-to-using-a-lichen-based-index-to-nitrogen-air- quality.aspx) and a low resolution pdf can be downloaded Bushy lichen from the APIS website (http://www.apis.ac.uk/guide-using- Bushy Leafy lichen lichen lichen-based-index-assess-nitrogen-air-quality). (green)

Lichens as indicators of nitrogen air quality

How and why were the indicator epiphytic Leafy lichen Crustose species and their host substrate selected? (brown) lichen

Epiphytic lichens growing throughout Europe have been 5cm shown to be good indicators of nitrogen air quality (Davies et al 2007, van Herk, 1999, Pinho et al. 2011, Wolseley et Figure 1. Branch showing the three different types of al. 2006, 2010, Seed at al. 2013). lichen (leafy, bushy and crustose).

1 Indicator lichens used in this guide fall into three Chemical tests can be used to help confirm growth forms: lichen identification Lichens may contain a great variety of chemical compounds, 1. Bushy lichen mainly produced by the fungal partner to protect the algal photobiont from adverse conditions caused by high sunlight, UV or drought. These compounds may be highly coloured Attached to the as in the bright yellow N-tolerant species of Xanthoria or bark at the base detected using a simple spot test that produces a distinct colour reaction in some species. If you are unsure of the identity of a species a spot test using household bleach may help. Follow the instructions provided in the guide and make sure that the colour response is correct. Remember that Branched and shrub-like, attached to the bark at the base. negative reactions are as informative as positive ones. Branches rounded in section or strap-like with a distinct upper and lower surface. What the index tells us about pollution levels at a site

Attached to Information on gaseous N concentrations was collected 2. Leafy lichen the bark from at the 29 sites where the lichen species composition was the lower evaluated by Lewis, 2012. The lichen composition was surface correlated with a range of gaseous pollutant concentrations.

The Field Manual is designed to provide a LIS index as an indicator of nitrogen air quality in a given location. It has

been correlated with mean gaseous ammonia (NH3) and

Leaf-like lobes closely or loosely attached to the bark from nitrogen dioxide (NO2) concentration data. A description the lower surface. of N sources can be found on the APIS ( information system) website http://www.apis.ac.uk/ overview/pollutants/overview sources.htm 3. Crustose or granular lichen What it doesn’t tell us

Closely attached to It was not possible to evaluate wet N deposition (i.e. N in the bark and cannot precipitation, cloud or dew) effects by the methods used be removed without by Lewis (2012). The indicator species and guide were cutting the bark developed from dry deposition, gaseous atmospheric concentrations alone. Likewise the index does not Figure 2. Schematic diagram of the three different discriminate between oxides of N and ammonia as both are types of lichen. often present. However, because concentrations of N oxides are less spatially variable except close to local sources their concentrations can be readily obtained from the APIS ‘Search by location’ tool (http://www.apis.ac.uk/search-by-location). Visible features of indicator lichens that can be used in their identification: Why would I want to know about concentrations Familiarise yourself with the terms in the glossary, referring of gaseous N pollutants at a site? to features found in lichens, such as the thallus or the body Conducting the lichen survey following the protocol outlined of the lichen, vegetative propagules, soredia and isidia in the guide and expanded on in this manual will enable you produced as a mechanism for distributing the photobiont to evaluate the risk from N pollution damage to sensitive (alga) and together. Fruiting bodies produce the vegetation growing at a site. APIS also provides habitat- spores of the fungus. The species in this guide may produce pollutant records that provide more information on impacts cup-shaped (see Xanthoria) or elongated (see Graphis and (http://www.apis.ac.uk/search-pollutant-impacts). Arthonia) fruiting bodies. If you have fruiting bodies on your specimen, check that the species and fruiting body Together this field manual and guide describe how surveying match their description and photograph. A brief glossary species/genera of epiphytic lichens growing on oak and birch is provided in the guide and a fuller glossary is available on can be used to estimate gaseous N concentrations in their the web at http://www.nhm.ac.uk/nature-online/life/plants- immediate locality. fungi/lichen-id-guide/glossary.dsml

2 How to survey in the vicinity of a N pollution The survey source (intensive animal husbandry units i.e. What type of sites can be surveyed? poultry, pig, dairy) The survey can be carried out in a wide variety of urban and The selection of sampling method depends on your rural locations with sufficient trees (five or more) within a objectives. If you want to establish the concentration reasonably confined area (approx 50 2m ). gradient away from source to your point of interest you can use the transect approach. Alternatively you may want to establish the N concentration at different points around the Why are surveys confined to oak and birch trees? point source. Oak and birch trees were chosen for the development of the N index, as they both have rather acid (low pH c. 3-4) If using the transect approach it is important to- bark compared to tree species such as ash and sycamore 1. Establish the prevailing wind direction. The transect which have a higher bark pH with lime trees in between. should be sited downwind of the point source, with an Bark pH changes in response to atmospheric nitrogen upwind background site. The distance and location of deposition and this affects the lichen communities colonising this background site will be influenced by the proximity the bark. In most cases atmospheric nitrogen causes an of other point sources. increase in bark pH and trees with a higher bark pH are more likely to support nitrogen-tolerant species of lichen. 2. Identify accessible trees and work out the distances Trees with a low bark pH tend to support nitrogen-sensitive from the pollutant point source prior to sampling. lichen species and this index measures the change from a 3. Have a greater frequency of sampling locations closer nitrogen sensitive to a nitrogen tolerant lichen community, if to the point source, as the ammonia concentration there is a change in N pollution. This means that surveying decreases exponentially with distance from the N trees that naturally have a higher bark pH is likely to produce source. Ammonia concentrations can be measured at different results from those with a low bark pH. background levels within c. 250-350 metres from the source. Do I get different results with trunks compared with branches: when and why? A useful link is The Simple Calculation of Atmospheric Impact Limits (SCAIL) model http://www.scail.ceh.ac.uk/ Epiphytic lichens tend to be slow-growing and long-lived which provides a suite of screening tools for assessing the so that lichens growing on older trunks may have become impact from agricultural and combustion sources on semi- established under different atmospheric conditions to natural areas. those on younger branch bark. Lichens on branches are recent colonisers and thus reflect the present atmospheric Tree density and shade conditions. In areas where atmospheric conditions have changed recently the observed lichen species on trunks • Lichens grow best in sunny exposed conditions. In and branches may be different. Where local atmospheric N highly shaded conditions they tend to be replaced by concentrations have increased, the LIS score may be lower algae and bryophytes. Preferably the site you want to on the branches than on the trunks where the LIS score may evaluate should have several exposed standard trees of be higher due to the survival of N-sensitive species. the same species, with at least some branches that you can reach (Figure 2).

In areas formerly affected by SO2 (sulphur dioxide) older trunks may continue to have a reduced number of lichens • Avoid sampling damaged trees or trees covered in ivy due to the legacy effect. Branches on these trees however, as both factors alter the bark conditions and also the may have grown under a different chemical environment, lichen communities. less influenced by sulphur and are likely to support a • When sampling on branches where possible choose different lichen community (Wolseley et al. 2006). the exposed sunny side of the tree and avoid shaded When sampling on branches, the three zones are designed branches. Choose accessible branches from the same to accommodate substrates of different ages. The zones tree species if not accessible from the same tree where are designated by distance from the growing tip with zone you sampled the trunk. 1 closest to the trunk. You may also find it easier to sample • How many trees should be sampled? A minimum of from zone 1 (the older section) first where lichens are older, 5 trees is recommended but surveying 10 trees would larger and easier to identify. be preferable. Sampling more trees reduces the impact of unrepresentative results. Three trees is the absolute minimum needed, but results for birch and oak e.g.3 birch and 2 oak, can be combined without affecting the LIS.

3 How to record indicator lichens on trunks • Familiarise yourself with the nitrogen indicator (sensitive and tolerant) lichens, and their characteristic features, illustrated in this guide.

• Locate a 50 x 10 cm area on each of the three aspects of the tree between 1.0 and 1.5 m above ground level.

• Restrict your recording to lichens listed in the guide and included in the downloadable recording forms. Ignore Figure 5. Three sampling zones along a branch. all other lichen species that may be present.

• Fill in the recording form, adding a 1 (present) against each N-sensitive and N-tolerant taxa growing between Glossary 1 m and 1.5 m above ground level on each of the three aspects (E, S & W) within the 50 x 10 cm area (Figure 4). A glossary of useful terms can be found at http://www.nhm. ac.uk/nature-online/life/plants-fungi/lichen-id-guide/glossary. dsml

Site Summary and Lichen recording forms with completed examples

Figure 3. Tree selection and sampling height. Instructions for filling in the Site Summary and Lichen recording forms • Go to the site you want to evaluate for gaseous N concentrations. Check first it is not on limestone http://maps.bgs.ac.uk/soilportal/wmsviewer.html

• Identify five or more oak (Quercus petraea, Q. robur), birch (Betula pendula, B. pubescens) trees or a mixture of the two species in a similar situation, not densely planted, shaded, not ivy-covered or damaged. Figure 4. Selection of three aspects, east, south, west but not north. • Select five trunks each single-stemmed and >40 cm girth

• Complete site information on Lichen recording forms How to record indicator lichens on branches (Form 1 trunks; Form 2 branches)

• Familiarise yourself with the nitrogen indicator (sensitive • For trunks-record presence or absence of lichens in wide and tolerant) lichens, and their characteristic features, strips (10 x 50 cm) between 1.0 and 1.5 m from the illustrated in this the guide. ground, in each of three aspects, East, South and West.

• Locate the zones along the selected branch. • For branches- If available select 3-5 accessible branches and record zone 1 (100-150 cm back from the tip), • Restrict your recording to lichens listed in the guide and zone 2 (50-100 cm), and zone 3 (0-50 cm). included in the downloadable recording forms. Ignore all other lichen species that may be present. • Record the presence of each species (not abundance) on Lichen recording form (Form 1). • Fill in the recording form, adding a 1 (present) for N-sensitive and N-tolerant taxa growing in each of the • Transfer data from the lichen recording form to the Site three zones (Figure 5). Once you have identified at least summary form (Form 3). one N-sensitive or N-tolerant. • You can upload your site summary results to the APIS There is only a requirement to find one N-sensitive and website by completing the online form at http://www. one N-tolerant lichen species for each zone. The presence/ apis.ac.uk/guide-using-lichen-based-index-assess- absence of all the listed lichens does not need to be nitrogen-air-quality/upload-results. We will be mapping recorded. Even though you have identified a N-sensitive all completed results to gain a picture of lichen and lichen it is necessary to ensure that there are no N-tolerant nitrogen interactions across the UK. You can be part of lichens present. this story by uploading your results too.

4 Suggested methods for marking a 10 x 50 frame on the tree trunks • Large map pins could be used. Caution when using these in case of injury.

• A double string with 3 sliding frames between the two strings. The double string 0.5 m apart would be long Figure 6. Stringed frame for identifying the three enough to use on a range of tree trunks (Figure 6). 10 x 50 cm aspects.

• a plastic ‘quadrat’ could be made using thick plastic and duct tape.

Form 1. Lichen recording form (Trunks)

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5 Form 2. Lichen recording form (Branches)

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6 Examples of completed Forms 1 &2

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7 Form 3. Blank Site Summary form

>ŽĐĂƚŝŽŶ ŝƌYƵĂůŝƚLJ 'ƌŝĚƌĞĨĞƌĞŶĐĞͬ'W^ ůƚŝƚƵĚĞŵ ŝ͘Ğ͘EdϮϰϱϲϳϴ ĞůĞƚĞĂƐŶĞĐĞƐĂƌLJ EŽŽĨƚƌƵŶŬƐƐƵƌǀĞLJĞĚ dƌĞĞƚLJƉĞƚƌƵŶŬ ŽĂŬ ďŝƌĐŚEŽŽĨďƌĂŶĐŚĞƐƐƵƌǀĞLJĞĚ dƌĞĞƚLJƉĞďƌĂŶĐŚŽĂŬďŝƌĐŚ ŽƵŶƚƐŽĨĂƐƉĞĐƚƐ >/^;EͲƐĞŶƐŝƚǀĞĂǀĞƌĂŐĞ EŽ͘ŽĨƚƌƵŶŬƐ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌƚƌƵŶŬ dƌƵŶŬƐ ǁŝƚŚEͲƐĞŶƐŝƚŝǀĞ ƐĐŽƌĞŵŝŶƵƐEͲƚŽůĞƌĂŶƚ ƐƵƌǀĞLJĞĚ ŝ͘Ğ͘ŽƵŶƚͬŶŽ͘KĨƚƌĞĞƐ ůŝĐŚĞŶƐ ĂǀĞƌĂŐĞƐĐŽƌĞ

ŽƵŶƚƐŽĨĂƐƉĞĐƚƐ EŽ͘ŽĨƚƌƵŶŬƐ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌƚƌƵŶŬ EY/ǀĂůƵĞ͘džƚƌĂĐƚĨƌŽŵ dƌƵŶŬƐ ǁŝƚŚEͲƚŽůĞƌĂŶƚ ƐƵƌǀĞLJĞĚ ŝ͘Ğ͘ŽƵŶƚͬŶŽ͘ŽĨƚƌĞĞƐ ĨŝŐƵƌĞϰ ůŝĐŚĞŶƐ

ŽƵŶƚƐŽĨnjŽŶĞƐ >/^;EͲƐĞŶƐŝƚǀĞĂǀĞƌĂŐĞ EŽ͘ŽĨďƌĂŶĐŚĞƐ ƌĂŶĐŚĞƐ ǁŝƚŚEͲƐĞŶƐŝƚŝǀĞ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌďƌĂŶĐŚ ƐĐŽƌĞŵŝŶƵƐEͲƚŽůĞƌĂŶƚ ƐƵƌǀĞLJĞĚ ůŝĐŚĞŶƐ ĂǀĞƌĂŐĞƐĐŽƌĞ

ŽƵŶƚƐŽĨnjŽŶĞǁŝƚŚ EŽ͘ŽĨďƌĂŶĐŚĞƐ EY/ǀĂůƵĞ͘džƚƌĂĐƚĨƌŽŵ ƌĂŶĐŚĞƐ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌďƌĂŶĐŚ EͲƚŽůĞƌĂŶƚůŝĐŚĞŶƐ ƐƵƌǀĞLJĞĚ ĨŝŐƵƌĞϰ 

You can upload your results to the APIS website by We will be mapping all completed results to gain a picture of completing the online recording form at http://www.apis. the lichen and nitrogen interactions across the UK. You can ac.uk/guide-using-lichen-based-index-assess-nitrogen-air- be part of this story by uploading your results here. quality/upload-results

Worked example of Site Summary form (Form 3)

>ŽĐĂƚŝŽŶ ŝƌYƵĂůŝƚLJ 'ƌŝĚƌĞĨĞƌĞŶĐĞͬ'W^ ůƚŝƚƵĚĞŵ ŝ͘Ğ͘EdϮϰϱϲϳϴ ĞůĞƚĞĂƐŶĞĐĞƐĂƌLJ EŽŽĨƚƌƵŶŬƐƐƵƌǀĞLJĞĚ dƌĞĞƚLJƉĞƚƌƵŶŬ ŽĂŬ ďŝƌĐŚEŽŽĨďƌĂŶĐŚĞƐƐƵƌǀĞLJĞĚ dƌĞĞƚLJƉĞďƌĂŶĐŚŽĂŬďŝƌĐŚ ŽƵŶƚƐŽĨĂƐƉĞĐƚƐ >/^;EͲƐĞŶƐŝƚǀĞĂǀĞƌĂŐĞ EŽ͘ŽĨƚƌƵŶŬƐ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌƚƌƵŶŬ dƌƵŶŬƐ ǁŝƚŚEͲƐĞŶƐŝƚŝǀĞ ϵ ϱ ϵͬϱсϭ͘ϴ ƐĐŽƌĞŵŝŶƵƐEͲƚŽůĞƌĂŶƚ ϭ͘ϴͲϭ͘ϮсϬ͘ϲ ƐƵƌǀĞLJĞĚ ŝ͘Ğ͘ŽƵŶƚͬŶŽ͘KĨƚƌĞĞƐ ůŝĐŚĞŶƐ ĂǀĞƌĂŐĞƐĐŽƌĞ

ŽƵŶƚƐŽĨĂƐƉĞĐƚƐ EŽ͘ŽĨƚƌƵŶŬƐ ǀĞƌĂŐĞƐĐŽƌĞƉĞƌƚƌƵŶŬ EY/ǀĂůƵĞ͘džƚƌĂĐƚĨƌŽŵ dƌƵŶŬƐ ǁŝƚŚEͲƚŽůĞƌĂŶƚ ϲ ϱ ϲͬϱсϭ͘Ϯ ϭ͘Ϭϱ ƚZŝƐŬ ƐƵƌǀĞLJĞĚ ŝ͘Ğ͘ŽƵŶƚͬŶŽ͘ŽĨƚƌĞĞƐ ĨŝŐƵƌĞϰ ůŝĐŚĞŶƐ

ŽƵŶƚƐŽĨnjŽŶĞƐ >/^;EͲƐĞŶƐŝƚǀĞĂǀĞƌĂŐĞ EŽ͘ŽĨďƌĂŶĐŚĞƐ ƌĂŶĐŚĞƐ ǁŝƚŚEͲƐĞŶƐŝƚŝǀĞ ϭϬ ϱǀĞƌĂŐĞƐĐŽƌĞƉĞƌďƌĂŶĐŚ ϭϬͬϱсϮ ƐĐŽƌĞŵŝŶƵƐEͲƚŽůĞƌĂŶƚ ϮͲϬ͘ϲсϭ͘ϰ ƐƵƌǀĞLJĞĚ ůŝĐŚĞŶƐ ĂǀĞƌĂŐĞƐĐŽƌĞ

ŽƵŶƚƐŽĨnjŽŶĞǁŝƚŚ EŽ͘ŽĨďƌĂŶĐŚĞƐ EY/ǀĂůƵĞ͘džƚƌĂĐƚĨƌŽŵ ƌĂŶĐŚĞƐ ϯ ϱǀĞƌĂŐĞƐĐŽƌĞƉĞƌďƌĂŶĐŚϯͬϱсϬ͘ϲ Ϭ͘ϳϴ ƚƌŝƐŬ EͲƚŽůĞƌĂŶƚůŝĐŚĞŶƐ ƐƵƌǀĞLJĞĚ ĨŝŐƵƌĞϰ 

8 This guide has been produced in physical states: gaseous (contributing to dry deposition) lichens on three aspects of the trunk (Fig. 1) and on • Identify the three aspects (E, S and W using a • You may have to modify these zones depending on Figure 2. Converting LIS into the N air quality index (NAQI) collaboration with: and dissolved (in rainfall, cloud and dew) contributing three sections of a branch of oak or birch trees (Fig. 2). compass) on the trunks that you will survey. the growth form of the trees that you are using. Three sampling zones Ǡ Guide to using a Centre for Ecology and Hydrology to wet deposition. Oxides of nitrogen (NO ) are mostly The assessment method is repeated on at least five See Field Manual for further details. along a branch x • The range of lichen indicator scores (LIS) is given on the Y axis (from www.ceh.ac.uk How to record indicator lichens on trunks lichen based index to produced through combustion, from power stations trees of the same species to obtain a LIS (Fig. 3). Using Ǡ • Use the same scoring procedure as you used for -3 to 3). and motor vehicles. These are emitted in gaseous form the LIS the NAQI for your site can be derived (Fig. 4). Natural History Museum trunks substituting the three aspects for three zones • Take the LIS you have just derived from your survey of either birch or www.nhm.ac.uk nitrogen air quality and some will be dry deposited locally, whereas most • Familiarise yourself with the nitrogen indicator along the branch. 101+ cm 51-100 cm 0-50 cm Not all of the listed species will be present at a site, (sensitive and tolerant) lichens, and their oak trees based on trunks and/or branches. The University of Nottingham will be transported in the atmosphere to be washed Zone 1 Zone 2 Zone 3 characteristic features, illustrated in this guide. www.nottingham.ac.uk out in wet deposition mostly as nitrate. Reduced forms but utilizing the presence or absence of any of the • Read across the graph until you meet the broken line drawn for branches. By Centre for Ecology and Hydrology, Natural N-tolerant or N-sensitive indicator lichens minimizes of nitrogen (NHx) have a more rural source, mainly • Restrict your recording to only lichens listed in this Drop down a line perpendicular to the X axis and read off the NAQI. If Sniffer History Museum and University of Nottingham any bias in the LIS index due to regional variation in Calculating your lichen indicator score (LIS) for trunks and branches from emissions associated with farming i.e. arable guide. the LIS has been derived from a survey of the trunks, use the solid line. www.sniffer.org.uk species distributions. and livestock; cattle, pigs and poultry. These are Joint Nature Conservation Committee - Locate a 50x10 cm area on each of the three aspects • A simple description of air quality is indicated by the coloured zones emitted as ammonia gas (NH ), some of which will The LIS is based on the difference between the presence • Count the number of aspects on all five trees that jncc.defra.gov.uk What does the guide do? 3 In conditions where concentrations of gaseous N of the tree between 1.0 and 1.5 m above ground level. (e.g. a LIS of “2”, based on branches, meets the line for branches in be dry deposited locally, with a larger fraction being of N-tolerant and N-sensitive lichens on three aspects support sensitive species i.e. a maximum value of 15 compounds are increasing the older bark of trunks may the green zone, which is indicative of a clean site with negligible Scottish Natural Heritage • Provides a simple, effective and robust method for - Record the presence of N-sensitive and of the trunk or on three zones of the branch. Populate could be obtained if each of the five trees supported transported in the atmosphere as aerosols and washed continue to support N-sensitive species while the younger www.snh.gov.uk + N-tolerant species growing between 1 m and 1.5 m Figure 3 (worked example) by allocating a score of 1 a tolerant species on each of the three aspects. gaseous N pollution; a LIS of “-2” meets the line for branches in the determining concentrations of gaseous nitrogen out in precipitation as ammonium ions (NH4 ). bark of the branches may be colonised by N-tolerant above ground level on each of the three aspects (E, S (presence) for one or more of the listed N-sensitive salmon pink zone, which is indicative of a very N polluted site). Scottish Environment Protection Agency (N) pollution that can be used by anyone interested • Divide the count by the number of trees recorded www.sepa.org.uk species. If possible survey both trunks and branches to and W) within the 50 x 10 cm area (see Figure 3. species. Allocate a score of 0 if N-sensitive species in the impacts of gaseous N on sensitive habitats to obtain an average value for both N-sensitive and Lichens as indicators find out about on-going changes in your environment. Northern Ireland Environment Agency in the UK. absent. Repeat process for N-tolerant species. Interpreting your score in a local and regional context of nitrogen air quality N-tolerant lichens. www.ehsni.gov.uk • Count the number of aspects on all five trees that • Includes a simple identification key to epiphytic The survey • Subtract the average for N-tolerant from the average support tolerant species. i.e. a maximum value of 15 • The LIS for a site can vary from +3 for clean (low concentrations of lichens growing on oak and birch trees that show Lichens are composite organisms comprising a S for N-sensitive to obtain a lichen indicator score (LIS). W E could be obtained if each of the five trees supported gaseous N compounds) sites where only N-sensitive indicator lichens distinct sensitivity to, or tolerance of, atmospheric symbiotic relationship between a single species of Ǡ Essential equipment to take with you a tolerant species on each of the three aspects. are present, to -3 for very high concentrations of gaseous nitrogen fungus and one or more species of algae. The Figure 3. Worked example of LIS calcualtion for 5 trunks N pollution. 1.5 m compounds sites where only N-tolerant indicator lichens are present. • This fold-out guide. Figure 1. fungal partner provides structure and protection for Three sampling • Provides a simple robust method to determine • Transitional sites may have both N-tolerant and N-sensitive taxa the algae, which through photosynthesis provides • Recording sheet, preferably waterproofed places on the Tree 1 Tree 2 Tree 3 Tree 4 Tree 5 Count Average levels of risk to a habitat from gaseous nitrogen west, south and present, especially where conditions are changing. energy and assimilates for the fungal partner. (download from Field Manual website). 1.0 m = Count pollution by calculating a standardised nitrogen air east of the Aspect W S E W S E W S E W S E W S E trunk no. trees (5) • If you compare the NAQI based on LIS for trunks with the LIS for quality index (NAQI). As organisms without roots, lichens obtain their • Tape measure. N-sensitive 1 0 1 1 1 1 1 0 0 0 1 0 1 0 1 9 1.8 branches and find that the LIS for branches is lower than that of the nutrients from the atmosphere and so are highly • Indicates nitrogen air quality at the location of the • Pencil or waterproof pen. trunks, it suggests that conditions are deteriorating in your site. susceptible to changes in atmospheric chemistry. In N-tolerant 0 0 0 1 0 0 1 1 1 1 0 0 0 0 1 6 1.2 trees sampled. Europe, lichens have been used as sensitive • Map to record location and GPS device if available. • However, there may be sites where conditions are improving (e.g. sites formerly affected by acid rain where there is very little lichen of air quality for more than a century. • x 10 hand lens as some lichen features are small. Lichen indicator score (LIS) = (Average N-sensitive)–(Average N-tolerant) 0.6 Field manual Recent research on oak and birch trees across the • Repeat this for each of the five trees. cover on the trunk, and yet the branches have N-sensitive taxa present). • Compass (or GPS) for locating trunk aspect. UK has identified lichens that are sensitive to, or There is no need to record the species present. However, ToThe estim lichenate the indicator LIS on bra nscoreches, r e(LIS)peat tandhe p rtheoce sNs aairs in qualityFigure 3 for N-sensitive and N-tolerant species on the three The information supporting the protocols zones on five sampled branches. tolerant of, increasing concentrations of nitrogenous recording the individual species can provide additional Further information underpinning this guide and suggested recording Ǡ Establish suitability of site for survey pollutants in the atmosphere. In the field, the information about the site (see Field Manual). Interpreting your LIS in sheets can be found in the Field Manual at Figure 4. This guide was written by P.A. Wolseley, I.D. Leith, L.J. Sheppard, J.E.J. Lewis, response to increasing atmospheric nitrogen pollution • Identify five or more oak or birch trees (not a mixture terms of exposure to The FSC (Field Studies Council) is an www.apis.ac.uk/nitrogen-lichen-field-manual. Relationship between the Lichen Indicator Score (LIS) P.D. Crittenden and M.A. Sutton, based on a PhD thesis “Biomonitoring for can be measured by the decrease in N-sensitive of the two) growing under similar environmental Recording indicator lichens on branches gaseous Nitrogen and N Air Quality Index (NAQI) independent educational charity committed Ǡ atmospheric nitrogen pollution using epiphytic lichens and bryophytes” by to raising awareness about the natural lichens and the increase in N-tolerant lichens. conditions (not densely planted or shaded). 3.0 Compounds world. The organisation works through a Background • Choose 3-5 branches on the same tree species (oak J.E.J. Lewis (University of Nottingham). Photographs are by Harry Taylor, Natural • Trees that are covered in ivy should not be used. History Museum. network of residential and day Centres Emphasis has been placed on the use of indicator lichens or birch) as used in trunk survey. Do not use fallen The fitted lines are derived 2.0 throughout the UK providing courses for

( L I S ) N polluted Very N polluted Air pollution has had widespread impacts on sensitive that do not require identification at the microscopic • Trees should be single stemmed (standard) with a from mean values taken from schools and colleges, leisure learning and

branches. e The Field Manual can be downloaded at: organisms since the industrial revolution. In the 1970s level and that are least likely to be confused with other straight trunk, > 40 cm in girth. the UK wide survey. 1.0 www.apis.ac.uk/nitrogen-lichen-field-manual professional development courses. The FSC

S c o r publishes many titles to support its work and 1980s, sulphur dioxide (SO ) was the principal species. In some cases, all species in a are known • If there are no suitable branches on these trees, The LIS NAQI relationship for 2 including the AIDGAP guides. For more • Look for availability / accessibility of branches. branches from other trees of the same species can branches should be read from 0 Branch Trunk OPAL www.opalexplorenature.org pollutant causing concern. Following the substantial to be sensitive (e.g. species of Usnea – the beard information, please contact: reduction in sulphur dioxide emissions, the main lichens). In other cases, an individual species within a • Avoid sites on calcareous soils. Determine the calcium be used. the broken line and for trunks

i n d c a t o r iSpot www.opalexplorenature.org/ispot FSC Publications from the solid line. -1.0 threat to sensitive vegetation now comes from genus may be an indicator (e.g. ). carbonate (CaCO3) soil levels in your location at Unit C1, Stafford Park 15, Telford TF3 3BB • Choose branches in an open aspect and within easy Clean At risk reactive nitrogen compounds in the atmosphere. http://maps.bgs.ac.uk/soilportal/wmsviewer.html Sites that are designated as clean T 0845 345 4072 F (01743) 852101 reach. L i c h e n -2.0 Printed using E [email protected] The Lichen Indicator Score (LIS) have an NAQI between 0 and 0.5, vegetable oil How to survey • Record the presence of N-sensitive and N-tolerant based inks W www.field-studies-council.org Nitrogen sources Ǡ at risk NAQI > 0.5-0.85, -3.0 Using easily identified indicator species we can indicator lichens in the three zones represented by 0 0.5 1.0 1.5 2.0 • Record the site location, grid reference and altitude. N polluted NAQI 0.86-1.25, calculate a lichen indicator score (LIS) based on the approximate distances along each main branch, Reactive nitrogen comes in two chemical forms: N Air Quality Index (NAQI) Text © NERC (CEH), © Sniffer, © JNCC, SEPA and NIEA © Crown copyright, © Pat Wolseley. 9 6 oxidised and reduced. These forms occur in two presence or absence of N-tolerant and N-sensitive • Record the tree species you are surveying. measured from the growing tip (see Figure 2). very N polluted NAQI > 1.25. Photographs by Harry Taylor. OP158. ISBN 978 1 908819 10 9.

Calculating your lichen indicator score (LIS) for measured NH3 concentration data and modelled NO2 trunks and branches concentration data. It was mathematically derived to be the best fit for the UK NH3 and NO data. NO concentrations The LIS is based on the difference between the presence 2 2 show much less local spatial variation than NH of N-tolerant and N-sensitive lichens on three aspects of 3 concentrations. Thus if you derive the site NAQI and use the the trunk or zones of the branch. Populate Forms 1 & 2 site grid reference to look up the NO concentration in APIS (worked examples of trunks and branches on page 7) by 2 (Air Pollution Information System) you can calculate the NH allocating a score of 1 (presence) for one or more of the 3 listed N-sensitive species. Allocate a score of 0 if N- sensitive species are absent. References

• Count the number of aspects on all 5 trees that support tolerant species. i.e. a maximum value of 15 could be concentration by substituting values in the above equation. obtained if each of the 5 trees supported a tolerant Davies, L., Bates, J. W., Bell, J. N. B., James, P. W. & Purvis, W. species on each of the three aspects. O. (2007). Diversity and sensitivity of epiphytes to oxides of • Count the number of aspects on all 5 trees that support nitrogen in London. - Environmental Pollution 146(2): 299-310. sensitive species i.e. a maximum value of 15 could be Lewis, J.E.J. (2012). Biomonitoring for atmospheric nitrogen obtained if each of the 5 trees supported a tolerant pollution using epiphytic lichens and bryophytes. PhD Thesis species on each of the three aspects. (http://etheses.nottingham.ac.uk/3573/) Divide the count by the number of trees recorded • Pinho, P., T. Dias, C. Cruz, Y. Sim Tang, M. A. Sutton, M.- to obtain an average value for both N-sensitive and A. Martins-Loução, C. Máguas & C. Branquinho (2011). N-tolerant lichens. Using lichen functional diversity to assess the effects of • Subtract the average for N-tolerant from the average for atmospheric ammonia in Mediterranean woodlands. - N-sensitive to obtain a lichen indicator score (LIS). Journal of Applied Ecology 48(5): 1107-1116.

• Don’t forget to upload your Site Summary results to Seed, L., Wolseley, P.A., Gosling, L., Davies, L. & Power, S. APIS: http://www.apis.ac.uk/guide-using-lichen-based- (2013). Modelling relationships between lichen bioindicators, index-assess-nitrogen-air-quality/upload-results air quality and climate on a national scale: results from the UK OPAL Air Survey. Environmental Pollution In press. The NAQI = 2 [NH ]^0.5 + [NO ]^0.5 using µmol,m3 3 2 Wolseley, P., James, P. W., Theobald, M. R. & Sutton, M. A. This equation has been derived using modelled and 2006). Detecting changes in epiphytic lichen communities

9 at sites affected by atmospheric ammonia from agricultural Yes. Calculation of the site specific index does not require sources. - Lichenologist 38(2): 161-176. the presence of all 8 + 9 taxa from the tolerant and sensitive functional groups. Realistically it is more likely that you will Wolseley, P., M. Sutton, I. D. Leith & N. van Dijk (2010): only find some or even none of the listed species. Epiphytic lichens as indicators of ammonia concentrations across the UK. - In: T. H. Nash, III, L. Geiser, B. McCune, D. Can a survey still be undertaken if there are not Triebel, A. M. F. Tomescu and W. B. Sanders: Biology five suitable trees at the selected site? of Lichens ― Symbiosis, Ecology, Environmental Monitoring, Systematics and Cyber Applications. Bibliotheca Yes, but a smaller number can influence your NAQI score Lichenologica No. 105. J. Cramer in der Gebrüder and increase level of uncertainty with odd results. Borntraeger Verlagsbuchhandlung, Stuttgart. 256 pages, pp.75-85. Is it necessary to survey both trunks and branches? Frequently asked questions No. Both will give an individual NAQI score but if possible it would be better to survey both, as the lichen present on the van Herk, CM (1999).Mapping of ammonia pollution with trunks may differ from those on the branches. epiphytic lichens in the Netherlands. - Lichenologist 31(1): 9-20. Will the lichens be the same on trunks and Can I conduct a survey if no oak or birch trees are branches? present at the site? Not necessarily. Branch lichens are probably more recently No, the relationship between LIS and NAQI was derived from colonised and the lichens present provide a more up to date epiphytic lichens growing on these tree species and has not indication of the N pollution climate. been tested beyond these host substrates. In addition, only birch or oak that exceed 1.5 m tall (are of sufficient age / Can other lichen species be used apart from the size to support lichens), do not support ivy, are healthy and ones listed in the Field Guide? not too densely planted are suitable. WHY? because these factors also influence which lichen species grow on the No. The research to calculate the NAQI established that substrate. these were the most appropriate indicator species to use.

How far apart can the individual trees be at Can a survey be conducted if none of the listed a location not obviously impacted by a point lichen species or taxa are present? source? No. The research to calculate the NAQI establish that these If the location is not close to a N point source then the trees were the most appropriate indicator species to use. could be up to 50 m apart. Is it necessary to identify to species level? How far apart can the individual trees be at a Only for some species but for example, Parmelia species do location impacted by a point source? not need to be identified to species as both Parmelia sulcata If using a transect approach, the trees growing at each and P. saxatilis are considered to be N-sensitive, so it is sampling location must be adjacent to each other (growing sufficient to identify that it is one of the Parmelia’s. in a clump of trees). For sampling locations close to the N source the sample trees should be in close proximity due to Is it correct that only one N-sensitive or one ammonia concentrations decreasing exponentially from N N-tolerant species needs to be present to give a source. score of 1? Yes. Can a mix of oak and birch be used to make up the five trunks or branches surveyed? If there are several of the lichen species on a Yes. The objective of the survey is to determine the presence trunk or branch the score will still be 1? or absence of N-sensitive and N-tolerant species and to Yes. The maximum score is 3 when an indicator is present on calculate a LIS. This can be achieved using a combination of 3 aspects of the trunk or 3 zones of the branch. oak and birch trunks and branches.

Fallen branches should not be used for the Can I conduct a survey if only a few of the survey? indicator species are present?

10