The spatial and seasonal variation of nitrogen dioxide and sulfur dioxide in Cape Breton Highlands National Park, Canada, and the association with lichen abundance Atmospheric Environment (original) (raw)
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Relationships between lichen community composition and concentrations of NO2 and NH3
Environmental Pollution, 2010
The relationship between different features of lichen communities in Quercus robur canopies and environmental variables, including concentrations of NO 2 and NH 3 was investigated. NO 2 concentration was the most significant variable, it was positively correlated with the proportion of lichen cover comprising nitrophytes and negatively correlated with total lichen cover. None of the lichen community features were correlated with NH 3 concentrations, which were relatively low across the site. Since nitrophytes and nitrophobes are likely to react in opposite directions to nitrogenous compounds, total lichen cover is not a suitable indicator for these pollutants. It is, therefore, suggested that the proportion of lichen cover comprising nitrophytes may be a suitable simple indicator of air quality, particularly in locations where the pollution climate is dominated by oxides of nitrogen.
Long distance nitrogen air pollution effects on lichens in Europe
The Lichenologist, 2003
The epiphytic lichen flora of 25 European ICP-IM monitoring sites, all situated in areas remote from air pollution sources, was statistically related to measured levels of SO 2 in air, NH 4 + , NO, ~ and SO 4 2 ~ in precipitation, annual bulk precipitation, and annual average temperature. Significant regression models were calculated for eleven acidophytic species. Several species show a strong negative correlation with nitrogen compounds. At concentrations as low as 0-3 mg N I" 1 in precipitation, a decrease of the probability of occurrence is observed for Bryoria capillaris, B. fuscescens, Cetraria pinastri, Imshaugia aleurites and Usnea hirta. The observed pattern of correlations strongly suggests a key role of NH 4 * in determining the species occurrence, but an additional role of NO," cannot be ruled out. Some species show a distinct response to current levels of SO 2 as well. It may be concluded that long distance nitrogen air pollution has strong influence on the occurrence of acidophytic lichen species. l\
Ecological Indicators, 2015
Biomonitoring can provide cost-effective and practical information about the distribution of nitrogen (N) deposition, particularly in regions with complex topography and sparse instrumented monitoring sites. Because of their unique biology, lichens are very sensitive bioindicators of air quality. Lichens lack a cuticle to control absorption or leaching of nutrients and they dynamically concentrate nutrients roughly in proportion to the abundance in the atmosphere. As N deposition increases, nitrogen-loving eutrophic lichens become dominant over oligotrophic lichens that thrive in nutrient-poor habitats. We capitalize on these characteristics to develop two lichen-based indicators of air-borne and depositional N for interior forested mountain ecosystems of the Pacific Northwest and calibrate them with N concentration measured in PM 2.5 at 12 IMPROVE air quality monitoring sites in the study area. The two lichen indices and peak frequencies of individual species exhibited continuous relationships with inorganic N pollution throughout the range of N in ambient PM 2.5 , suggesting that the designation of a critical level or critical load is somewhat arbitrary because at any level above background, some species are likely to experience adverse impacts. The concentration of N in PM 2.5 near the city of Spokane, Washington was the lowest measured at an instrumented monitoring site near known N pollution sources. This level, 0.37 g/m 3 /year, served as a critical level, corresponding to a concentration of 1.02% N in the lichen Letharia vulpina, which is similar to the upper end of background lichen N concentrations measured elsewhere in the western United States. Based on this level, we estimate critical loads to be 1.54 and 2.51 kg/ha/year of through-fall dissolved inorganic N deposition for lichen communities and lichen N concentration, respectively. We map estimated fine-particulate (PM 2.5 ) N in ambient air based on lichen community and lichen N concentration indices to identify hotspots in the region. We also develop and map an independent lichen community-based bioclimatic index, which is strongly related to gradients in moisture availability and temperature variability. Lichen communities in the driest climates were more eutrophic than those in wetter climates at the same levels of N air pollution.
Terricolous lichens as indicators of nitrogen deposition: Evidence from national records
Ecological Indicators, 2012
Determinants of plant community diversity and structure Generalised additive models Heathland Terricolous lichens a b s t r a c t Large areas of Great Britain currently receive nitrogen (N) deposition at rates which exceed the thresholds above which there is risk of damage to sensitive components of the ecosystem (critical loads for nutrient nitrogen and critical levels for ammonia), and are predicted to continue to do so. Excess N can damage semi-natural ecosystems. Lichens are potentially sensitive to air quality because they directly utilise nutrients deposited from the atmosphere thus may be good indicators of air quality. We used data from the British Lichen Society (BLS) database, which records the presence of all lichen taxa growing in Britain at 10 km resolution. The probability of presence of a taxa at a given level of N deposition was analysed together with driver data for climate, change in sulphur deposition, land-use and N deposition using generalised additive models (GAMs). Many taxa showed negative responses to N deposition with reductions in the probability of presence as N deposition increased. In all of the habitats, there were a mix of terricolous taxa which showed negative or no significant relationship with N deposition. Most of the taxa with negative relationships with N deposition started to decline in prevalence at the lowest levels of deposition found in this study. Levels of deposition over which a negative response apparently occurs are lower than those at which critical loads have been set for some habitats. These findings suggest that some terricolous lichen taxa are sensitive to atmospheric N deposition and even low levels of nitrogen deposition could be damaging terricolous lichen communities making then potentially good indicators of N deposition.
Lichen bioindicators of nitrogen and sulfur deposition in dry forests of Utah and New Mexico, USA
Ecological Indicators
Anthropogenic nitrogen (N) and sulfur (S) deposition can negatively affect ecosystem functions and lichen biomonitors can be a cost-effective way to monitor air pollution exposure across the landscape. Interior dry forests of the southwestern United States face increasing development pressures; however, this region differs from others with well-developed biomonitoring programs in having drier climates and a greater fraction of deposition delivered in dry forms. We measured throughfall N and S deposition at 12 sites in Utah and 10 in New Mexico and co-located collection of 6 lichen species. Throughfall N deposition ranged from 0.76 to 6.96 kg/ha/ year and S deposition from 0.57 to 1.44 kg/ha/year with elevated levels near human development that were not predicted by commonly used simulation models. Throughfall N was 4.6 and 1.6 times higher in summer compared with fall-spring in Utah and New Mexico and S deposition was 3.9 and 1.8 times higher in summer. Lichen N and S concentrations ranged from 0.97 to 2.7% and 0.09 to 0.33%. Replicate samples within plots showed high variability in N and S concentrations with within-plot coefficients of variation for N ranging between 5 and 10% and for S between 7 and 15%. In Utah, N and S concentrations in lichen species were correlated with each other in most cases, with R 2 ranging from 0.52 to 0.85. N concentrations in Melanohalea exasperatula and Melanohalea subolivacea could be correlated with average annual throughfall N deposition in Utah (R 2 = 0.58 and 0.31). Those relationships were improved by focusing on deposition in fall-spring prior to lichen sampling in Utah (R 2 for M. exasperatula, M. subolivacea, and X. montana = 0.59, 0.42, and 0.28). In New Mexico, lichens exhibited greater coefficients of variability within plots than between plots and could not be correlated with throughfall N deposition. In neither study area was S correlated between lichens and throughfall deposition, which may be the result of low S deposition over a narrow deposition range or complex lichen assimilation of S. Lichen biomonitoring for N deposition in the region shows promise, but could potentially be improved by sampling more thalli to reduce within-plot variability, repeated lichen collection synchronized with throughfall changeouts to explore temporal variability, and washing lichen collections to distinguish N and S that has been incorporated by the thalli from dry deposition that may accumulate on lichen surfaces.
Environmental Pollution, 2017
Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales.
Forest Ecology and Management, 2013
Anthropogenic nitrogen (N) deposition has had substantial impacts on forests of North America. Managers seek to monitor deposition to identify areas of concern and establish critical loads, which define the amount of deposition that can be tolerated by ecosystems without causing substantial harm. We present a new monitoring approach that estimates throughfall inorganic N deposition from N concentration in lichens collected on site. Across 84 study sites in western North America with measured throughfall, a single regression model effectively estimated N deposition from lichen N concentration with an R 2 of 0.58 and could be improved with the addition of climate covariates including precipitation seasonality and temperature in the wettest quarter to an R 2 of 0.74. By restricting the model to the more intensively sampled region including Oregon, Washington, and California, the R 2 increased to 0.77. Because lichens are readily available, analysis is cost-effective, and accuracy is unaffected by mountainous terrain, this method allows development of deposition estimates at sites across broad spatial and topographic scales. Our approach can allow land managers to identify areas at risk of N critical load exceedance, which can be used for planning and management of air pollution impacts.