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The influence of bird droppings and uric acid on the radial growth of five species of saxicolous lichens
Abstract
Bird droppings were applied over 1 year as a thick paste and as a suspension in deionized water to five species of lichens with different distributions on and off bird perching stones. The paste and suspension increased the radial growth of Parmelia conspersa while the paste increased the growth of Xanthoria parietina and reduced the growth and caused loss of colour in Parmelia glabratula ssp. fuliginosa. There were no statistically significant effects of paste or suspension on the growth of Physcia grisea or Parmelia saxatilis. In P. conspersa and X. parietina the growth responses were similar through the year but in P. glabratula the inhibitory effect of the paste was significant after 8 months growth. Application of a suspension of uric acid over 1 year had no statistically significant effects on the growth of P. conspersa, P. glabratula or X. parietina and was unlikely to be responsible for the effects of bird droppings on growth. The growth responses of the five species agreed well with their distributions in the field.
... A broad range of environmental pollutants are welldocumented as a source of architectural stone decay, with both limestone and many sandstones especially prone to attack by acids and salts. Of concern are atmospheric pollutants, i. e. gaseous pollutants, particulate matter, acid rain etc. [1][2][3], pollutants originating from the ground, ingressing through capillary action (rising damp) [1,4,5] or via deposition through urination [6], as well as biological decay agents such as vascular plants [7,8], lichen [9,10] and fungi [11]. Birds often introduce the seeds or spores of these biological decay agents, but more importantly, the bird's faecal matter can serve as a growing substrate for these agents. ...
... Experimental studies have shown that the pH of fresh pigeon excreta, once voided, undergoes a change towards the acidic, presumably caused by the growth of mould [19]. Both urine and faeces have also been implicated in the supply of phosphorus and nitrates either by direct application [9,10,20,21], leaching from perches [22], and aerial dispersal of dust derived from bird droppings on surfaces [23], thereby creating conditions suitable for the growth of ornithocoprophilous flora [21,24], primarily lichen [9,25] and fungi [26]. In addition, bacterial flora associated with lichen releases sulphuric and nitric acids that have been shown to cause the decay of the calcium carbonate (CaCO 3 ) binders of sand-and lime stones [27,28] with long-term effects even after cleaning [29]. ...
... Experimental studies have shown that the pH of fresh pigeon excreta, once voided, undergoes a change towards the acidic, presumably caused by the growth of mould [19]. Both urine and faeces have also been implicated in the supply of phosphorus and nitrates either by direct application [9,10,20,21], leaching from perches [22], and aerial dispersal of dust derived from bird droppings on surfaces [23], thereby creating conditions suitable for the growth of ornithocoprophilous flora [21,24], primarily lichen [9,25] and fungi [26]. In addition, bacterial flora associated with lichen releases sulphuric and nitric acids that have been shown to cause the decay of the calcium carbonate (CaCO 3 ) binders of sand-and lime stones [27,28] with long-term effects even after cleaning [29]. ...
Pigeon droppings are implicated in spoiling and decay of buildings. Several studies have examined the effects and chemistry of accumulations of pigeon droppings under highly localised pigeon roosts. Scant information exists on the impact caused by individual pigeon droppings at perch sites, even though these constitute the majority of bird use in urban areas. This study experimentally examined the processes that affect masonry immediately after pigeon excreta have been voided from the body and what effects discrete, fresh pigeon droppings have on different kinds of sandstone. The experiments demonstrated the susceptibility of freshly deposited excreta to environmental conditions (relative humidity and precipitation). In real-life situations, with pigeon excreta deposited on window ledges, cornices and parapets, the majority of damage would occur within the first two weeks of deposition. After that, the majority of individual droppings would have either dissolved or desiccated to such a degree that they would have rolled off. Much of the observed staining is superficial. While individual bird droppings make a building look dirty, even for months at a time, the effect on the building material is not substantial unless other factors come into play such as colonisation of the excreta by mould or leaching of salts from the excreta.
... Experimental studies have shown that nitrophilous species such as Xanthoria parietina (L.) Th. Fr. thrive at eutrophicated sites and may grow poorly when transplanted away from them (Armstrong 1984). Provision of additional nutrients increases the radial growth rate of nitrophilous lichen species (Armstrong 1984; Crittenden et al. 1994; Sanchez-Hoyos & Manrique 1995; Miller & Brown 1999) by as much as 15– 32% per year (Lewis-Smith 1995), while inhibiting growth in acidophytic species (Vagts & Kinder 1999). ...
... Fr. thrive at eutrophicated sites and may grow poorly when transplanted away from them (Armstrong 1984). Provision of additional nutrients increases the radial growth rate of nitrophilous lichen species (Armstrong 1984; Crittenden et al. 1994; Sanchez-Hoyos & Manrique 1995; Miller & Brown 1999) by as much as 15– 32% per year (Lewis-Smith 1995), while inhibiting growth in acidophytic species (Vagts & Kinder 1999). Armstrong (2000) found that nutrient enrichment reduced the thallus area of the acidophytic Parmelia saxatilis which possibly explains its low frequency on nutrient enriched rocks. ...
... The lower growth rate observed for X. parietina could be a consequence of the high N content of Hoagland's Solution. Since X. parietina is abundant near bird perching sites and in areas where eutrophication from animals occurs, it may follow that nitrogenous compounds associated with fecal deposits are necessary to increase thallus growth in this species (Armstrong 1984). Alternatively X. parietina may require an elevated pH or perhaps a specific nutrient/pH combination (A. ...
A field experiment was established to examine the effect of nutrient addition on the growth and competitive abilities of Parmelia caperara, P. saxatilis and Xanthoria parietina. Thallus fragments were attached to roofing slates in a split-plot experimental design in monospecific and multispecific mixtures and sprayed with nutrient solution at application frequencies representing a range of nutrient enrichments. Growth rates were measured as change in thallus diameter and the strength of competition determined by counting the number of thallus overlaps. Nutrient application significantly affected thallus growth with medium application rates promoting more thallus growth than controls (distilled water) or higher application rates in all three species. Nutrient addition at medium applications significantly increased the number of thallus overlaps made by all three species compared with controls, suggesting that competition became more intense. Although symmetrical competition was observed between all three species it was noted that growth and competition of thalli in two-species mixtures could not be used to predict the result in three-species mixtures. These results suggest that elevated nutrient levels can affect lichen growth rates and competition between thalli, leading to alterations in lichen community structure.
... This phenomenon has been observed and described mostly from maritime and oceanic islands, as well as coastal areas of different parts of the world, but several studies have also been undertaken in forest ecosystems (Maesako 1991(Maesako , 1999Ishida 1996;Mun 1997;Ź ó łkó ś & Markowski 2006;Ź ó łkó ś & Meissner 2008;Garcia et al. 2011). Lichen diversity, community or competition studies in bird-influenced sites have been carried out in saxicolous habitats (Grönlie 1948;Armstrong 1984Armstrong , 1994Armstrong , 2000Sancho 1988;Valladares & Sancho 1993;Kotlov 1994), but there is only one study pertaining to lichens in forests affected by bird colonies (Ź ó łkó ś et al. 2013). ...
... Our peripheral zone (transects D & C) had similar or lower numbers of lichen species than the accumulation zone (transects A & B). Armstrong (1984), having applied bird droppings to saxicolous lichen communities, found an increase in growth of the nitrophilous Xanthoria parietina and an inhibition of the acidophilous Melanelixia fuliginosa, the inhibitory effect becoming significant after only eight months. Lichen community changes at the edge of our cormorant colony were more pronounced and more rapid. ...
... The reason for this may be due to several factors, one of which is the quality and quantity of bird excreta involved. The chemical composition of excreta largely depends upon bird diet (Asman et al. 1982), and therefore the bird droppings of the non-piscivorous birds studied by Valladares & Sancho (1993) and employed by Armstrong (1984) cannot, apparently, be compared to cormorant excreta. Another factor is the amount of faeces: it is estimated that cormorants produce 2Á2 t ha -1 month -1 of excreta in areas of high nest density during the breeding season, which corresponds to c. 10 000 times and 120 000 times that of the normal input via precipitation of N and P, respectively (Kameda et al. 2000). ...
Lichen community changes were investigated on trees within a colony of great cormorants
(Phalacrocorax carbo sinensis) established in a pine forest on the Curonian Spit, western Lithuania. The impact of birds on the forest has altered the number and characteristics of substrata available to lichens. The lowest number of lichen species and occurrences was registered on trees in the most active part of the colony with the highest nest density. Lichen community patterns were most strongly related to P and Ca content in substrata and pH values. Some acidophytic species showed negative correlations, both with long-term and short-term ornithogenic influence. However, three acidophytes (Chaenotheca ferruginea, Lepraria incana, Coenogonium pineti) demonstrated an affinity for the transitional zone and recently occupied trees, and furthermore, C. pineti
apparently reacted positively to a short-term ornithogenic influence but negatively to a long-term one. These three lichens, along with algae, were the main, and often the only, components of epiphytic communities on trees at the edge of the colony and apparently indicated the crucial point of the acidophytic community under the increasing load of nutrients. All nitrophytic species showed an affinity for a long-term bird influence and reacted negatively to a short-term influence. Only free-living algae (predominating species
Desmococcus olivaceus) showed a clear affinity for trees occupied by bird nests. Hypogymnia physodes was found to be an indicator for early environmental changes following eutrophication. The study also showed that high concentrations of P did not have a mitigating effect on the detrimental impact brought about by increases in N and pH levels, but was possibly equally detrimental to acidophytic lichens.
... We have noted presence of a lichen Xanthoria spp. on the rocks around the pool (at the distance less than 1 m), which is a good indicator of frequency of the bird visits. This lichen requires large amounts of nitrogen compounds present in bird droppings [Armstrong, 1984]. We also noted the presence of other animal taxa (including potential predators) in some of pools. ...
We studied the species composition and the occurrence frequency of Cladocera in rock pools of the White Sea islands (Kandalaksha Gulf). In the course of our research 13 freshwater cladoceran species were identified, with occurrence frequency for nine of them exceeding 5%. Alonella excisa and Daphnia curvirostris were found in the White Sea rock pools for the first time. No differences in species composition were found between different archipelagos in study area. Plotted accumulation curves revealed that complete inventory of island cladoceran fauna requires sampling of 25-50 pools per island. Species richness does not correlate with either size of the island or its remoteness from the continent. It turned out thai an island closest to the continent demonstrates the lowest species richness (three Cladocera species), which is consistent with data on continental pools from other studies. The reasons of such a depleted species richness are discussed.
... Properties of cultural and historic significance are subject to a diverse array of threats, ranging from fast-acting impacts during natural disasters (Spennemann and Graham, 2007;Spennemann and Look, 1998) to slow-acting decay from a number of sources such as acid rain (Baedecker and Reddy, 1993;Haneef et al., 1992), damp ingress (Shupe et al., 2003), salt crystallisation (Cardell et al., 2003;Spennemann, 2001), and urban air pollution (Cappitelli et al., 2007;Nuhoglu et al., 2006) as well as biological decay caused by vascular plants (Spennemann and Look, 2006;Spennemann and Lorence, 2006), lichen (Armstrong, 1984;Cámara et al., 2014), fungi (Gorbushina and Petersen, 2000) and termites (Han et al., 2014). ...
PURPOSE: There is much anecdotal evidence that birds and their droppings are a major problem for the heritage profession. The purpose of this paper is to examine how serious heritage practitioners consider the bird impact to be.
DESIGN/METHODOLOGY/APPROACH: An online survey was conducted of 59 Australian heritage professionals of between one and >20 year’s experience in the field.
FINDINGS: Bird impacts were not considered of major concern to buildings. The longer experience a practitioner had, the less likely the impacts were considered an issue. Feral pigeons were deemed the most problematic, followed by cockatoos, starlings, swallows, seagulls, mynas, sparrows, cormorants, ibis, ducks and birds of prey. The professionals ranked common deterrent methods. The highest-ranking deterrents were bird netting and bird spikes, but they were only considered moderately effective. The costs of installation and maintenance, as well the ease of installation, were all deemed significantly less important than the physical impact, the aesthetic sympathy and the effectiveness of a deterrent method.
PRACTICAL IMPLICATIONS: This study indicates that the impact of birds on buildings in Australia may be of less concern than previously thought, and may be driven by other factors (i.e. aesthetics, commercial companies) rather than actual effects.
ORIGINALITY/VALUE: This is first study of its kind that surveyed the experiences of a wide range of heritage practitioners.
... However, little has been published on the influence of bird colonies on the occurrence and species composition of lichen biota, and what has been published focused mainly on the detection of changes in thallial growth caused by the deposition of bird droppings or the development of ornithocoprophilous lichen communities on rocks (e.g. Grö nlie 1948;Barkman 1958;Armstrong 1984Armstrong , 1994Armstrong , 2000Seppelt et al. 1988;Olech 1990;Valladares & Sancho 1993;Nash 2008). The impact of bird colonies on the epiphytic lichen biota does not appear to have been studied previously, although some research has focused on myxomycetes in the great cormorant colony in Lithuania (Adamonyte ˙ et al. 2013). ...
Bird colonies affect all elements of inhabited ecosystems, such as the soil, floristic composition and phytocoenosis structure, including the lichen biota. To date, the few papers focusing on changes in the composition of lichen vegetation caused by bird colonies are concerned with saxicolous ornithocoprophilous communities. The aim of this study was to define the impact of the grey heron in two breeding colonies on epiphytic lichens on Scots pines presently inhabited by birds, as well as those recently abandoned. Analysis of the lichen biota showed that the species composition and number of lichens were significantly modified in the functioning colony and the post-colony areas when compared with the control plots never inhabited by grey heron. Within the functioning and post-colony areas, mainly species with a wide ecological amplitude and those characteristic of fertile habitats dominated, while acidophilous and ubiquitous taxa occurred in the control plots. Multivariate analyses (for species abundance and ecological characteristics) showed that lichens growing within the functioning colony and post-colony areas differed significantly from those in the control area in their habitat requirements, as they demanded nutrient-rich, low or moderately moist and deacidified bark. Within the control plots, lichens preferring a relatively acidic and slightly nitrified substratum occurred. The direct impact of bird excrement and the fertilized bark could cause significant modifications in qualitative and quantitative species composition compared to the epiphytic lichen biota usually occurring on Scots pines.
... Both urine and faeces not only directly affect the chemical composition of the stone surface and thus cause chemical decay, they also have been implicated in the supply of phosphorus and nitrates either by direct application (McIlroy de la Rosa et al., 2013;Cámara et al., 2014), or by leaching from perches (Cardell et al., 2003), thereby creating conditions suitable for the growth of ornithocoprophilous flora (García-Rowe and Saiz-Jimenez, 1991), primarily lichen (Armstrong, 1984) and fungi (Bassi and Chiatante, 1976). In addition, bacterial flora associated with lichen releases sulphuric and nitric acids that have been shown to cause the decay of the calcium carbonate (CaCO 3 ) binders of sand and limestone (Warscheid and Braams, 2000). ...
,Purpose:
Birds are implicated in spoiling and decay of buildings, especially through their droppings. Pigeons are considered the main culprits, and several studies have examined the effects and chemistry of accumulations of droppings without evidence to the exact origins of the source of the excreta.
Design/methodology/approach
This study reviews and summarises the state of knowledge with regard to the impact of bird excreta on buildings. It experimentally assesses the acidity of fresh pigeon excreta with different diets and examines the development of the acidity of the excreta after voiding.
Findings
Feral pigeons in urban settings are known to feed of a range of foods. Urban food scraps-derived diets produce more acidic excreta than more natural diets such as seeds. Our paper the first study of its kind to examine the impact of a bird’s diet on the pH and thus the resulting (potential) decay of masonry
Practical implications
The study showed that from a management perspective, pigeons that subsist entirely on human provided foods will be depositing more initially acidic faeces. If faecal accumulation occurs, then mould and other bacteria quickly alter the chemistry from acidic towards basic, but the damage may already be done.
Originality/value
This paper is the first study of its kind to examine the effects of fresh pigeon droppings of known origin and age once voided from the intestine. This allows us to assess the impact during the first few days.
Preprint accessible via this link
http://www.emeraldinsight.com/doi/pdfplus/10.1108/IJBPA-09-2016-0023
Lichenometry—a method developed by geologists for dating Holocene moraines and other landforms—has many potential applications in archaeology. Maximum-diameter lichenometry can suggest ages for features that were initially lichen-free, such as the moai of Easter Island, and rock surfaces exposed by toolstone quarrying. Size-frequency analysis can provide dates for structures built of lichen-covered rocks, such as game-drive walls and blinds, meat caches, and tent rings. Both methods require local calibration curves, best constructed by measuring lichens on substrata of known exposure age. Most lichenometric studies have involved yellow members of the crustose genus Rhizocarpon, which grow slowly and can live for as long as 10,000 years. Lichenometry has been particularly successful on siliceous rock types in arctic, subarctic, and alpine-tundra environments. The effects of wildfire and of competition from foliose lichens make the technique less well suited for forested terrain. Few data are available for tropical or desert environments or for calcareous substrata. The reliability of a lichenometric date will depend on the quality of the calibration curve, the size of the sample, the nature and postoccupational history of the substratum, and the ability of the archaeologist to recognize potential disturbance factors. An ecological perspective is essential. Known archaeological applications and problems are discussed.
The majority of studies of the effects of environmental factors on lichen growth have been carried out in the field. Growth of lichens in the field has been measured as absolute growth rate (e.g. length growth, radial growth, diameter growth, area growth, or dry weight gain
per unit of time) or as a relative growth rate, expressed per unit of thallus area or weight, e.g. thallus specific weight. Seasonal fluctuations in growth in the field often correlate best with changes in average or total rainfall or frequency of rain events through the year. In some regions of the world, temperature
is also an important climatic factor influencing growth. Interactions between microclimatic factors such as light intensity, temperature, and moisture are particularly important in determining local differences in growth especially in relation to aspect and slope of rock surface, or height on a tree. Factors associated with the substratum
including type, chemistry, texture, and porosity can all influence growth. In addition, growth can be influenced by the degree of nutrient enrichment of the substratum associated with bird droppings, nitrogen, phosphate, salinity, or pollution. Effects of environmental factors on growth can act directly to restrict species distribution or indirectly by altering the competitive balance among different species in a community.
The passive uptake of ammonium ions to extracellular cation binding sites has been demonstrated for a range of lichen species. The possible competitive effect of other cations on ammonium binding is discussed. Binding of uncharged gaseous ammonia to exchange sites was also shown. The rapid loss of exchangeable ammonium from extracellular sites has been demonstrated and, because the greatest losses occur in living material, intracellular uptake is inferred. The labile nature of bound ammonium means that transfer of material to the laboratory for analysts may result in the underestimation of the amount bound.
Radial growth of mature Xanthoparmelia lineola and X. subdecipiens thalli (n = 10 thalli, 170 lobes) was measured bimonthly for 2 yr at a transplant locality on the East Slope of the Colorado Front Range (altitude 2,565 m). Growth occurred during every measurement period, but was most rapid in May, June, July, and August. Ninety-three percent of seasonal growth-rate variation during the first year of the study, and 92% during the second year, are explained by differences in the duration of daytime, snow-free thallus moisture (moisture available for photosynthesis); the strength of the relationship suggests that a positive net carbon assimilation rate is translated almost immediately into lobe elongation. No negative correlation was found between radial growth and thallus moisture recorded at night or beneath snow. In the cool, continental environment of the study area, duration of photosynthetically significant thallus moisture is influenced more strongly by air temperature, day length, and snow cover than by total precipitation. At higher altitudes and latitudes, where lichenometry is used for dating, these factors will have even greater importance.
Xanthoria parietina, a conspicuous orange foliose lichen, has been doubtfully recorded as part of the Ontario lichen flora because the previous documented reports were very old (1868 and 1917) and it had never been reported since. Here, we document a number of new sightings, all in southern Ontario. A previous report of this lichen from “Longulac” that was interpreted as Long Lake in Frontenac County is corrected to Longlac in the Thunder Bay District, and the specimen proved to be Xanthomendoza hasseana. A search for the lichen around Belleville, one of the original localities, proved fruitless. It is still not clear whether the new sightings of Xanthoria parietina represent a reintroduction of this coastal species to the inland sites, or whether the lichen has persisted in southern Ontario for almost 140 years, but was never reported. Substrate enrichment (eutrophication due to agricultural activity) in the region is one explanation for the spread of the lichen in southern Ontario.
Lichens exhibit the classic features of stress-tolerant organisms, viz. slow growth rates, considerable longevity, low demand for nutrients, and the presence of specific adaptations to survive in the most inhospitable environments on Earth. The ability of lichens to tolerate the extremes posed by deserts, polar regions, and chemically rich environments involves both morphological and physiological adaptation and changes in ecological behaviour so that species adapt to relatively protected niches within an extreme environment. This chapter discusses those aspects of the lichen symbiosis relevant to survival in extreme conditions and then describes the adaptation of lichens to (1) wet forests, (2) deserts, (3) the Arctic, (4) alpine regions, (5) Antarctica, (6) chemically rich environments, and (7) extraterrestrial environments such as outer space and Mars. It is evident that the lichen symbiosis is more tolerant to hostile conditions than its symbionts, morphological and physiological adaptations are intimately associated, and convergent evolution has resulted in similar changes in different environments.
The passive uptake of ammonium ions to extracellular cation binding sites has been demonstrated for a range of lichen species. The possible competitive effect of other cations on ammonium binding is discussed. Binding of uncharged gaseous ammonia to exchange sites was also shown. The rapid loss of exchangeable ammonium from extracellular sites has been demonstrated and, because the greatest losses occur in living material, intracellular uptake is inferred. The labile nature of bound ammonium means that transfer of material to the laboratory for analysis may result in the underestimation of the amount bound. (C) 1999 The British Lichen Society.
Lichens in the genus Xanthoparmelia were studied at altitudes of 2545-2570 m on the East Slope of the Colorado Front Range. Xanthoparmelia lineola and X. subdecipiens were the most numerous of 5 moprhologically similar nonisidiate chemotypes. Xanthoparmelia lineola grows 35% faster than X. subdecipiens during its linear growth phase. It is more tolerant of late-lying snow, but less tolerant of dark-colored, mafic rock substrates. Absence of extremely large Xanthoparmelia thalli in the study area is attributed to former episodes of increased snow cover. -from Authors
This review considers various aspects of the growth of foliose lichens including early growth and development, variation in
radial growth rate (RaGR) of different species, growth to maturity, lobe growth variation, senescence and fragmentation, growth
models, the influence of environmental variables, and the maintenance of thallus symmetry. The data suggest that a foliose
lichen thallus is essentially a ‘colony’ in which the individual lobes exhibit a considerable degree of autonomy in their
growth processes. During development, recognisable juvenile thalli are usually formed by 15months to 4years while most mature
thalli exhibit RaGR between 1 and 5mm yr−1. RaGR within a species is highly variable. The growth rate-size curve of a foliose lichen thallus may result from growth
processes that take place at the tips of individual lobes together with size-related changes in the intensity of competition
for space between the marginal lobes. Radial growth and growth in mass is influenced by climatic and microclimatic factors
and also by substratum factors such as rock and bark texture, chemistry, and nutrient enrichment. Possible future research
topics include: (1) measuring fast growing foliose species through life, (2) the three dimensional changes that occur during
lobe growth, (3) the cellular changes that occur during regeneration, growth, and division of lobes, and (4) the distribution
and allocation of the major lichen carbohydrates within lobes.
KeywordsRadial growth rate (RaGR)–Dry weight gain–Growth models–Aging and regeneration–Thallus symmetry
Competition between four foliose lichen species, common on slate rock surfaces in South Gwynedd, Wales, UK, was studied in experimental plots with and without nutrient enrichment by bird droppings. Fragments of the four lichens were glued to pieces of slate on horizontal boards in monoculture and in two-, three- and four-species mixtures in a factorial experimental design. In monoculture, nutrient enrichment increased thallus area of Parmelia conspersa (Ehrh. ex. Ach.) Ach., decreased thallus areas of Parmelia saxatilis (L.) Ach. and Parmelia glabratula ssp. fuliginosa (Fr. ex. Duby) Laundon, and did not affect thallus area of Phaeophyscia orbicularis (Necker) Moberg compared with untreated thalli. In the mixtures, P. conspersa and Ph. orbicularis were equally effective competitors in plots with and without nutrient enrichment. Addition of bird droppings, however, altered the ability of P. saxatilis and P. glabratula ssp. fuliginosa, to compete with the other species, the competitive ability of both species being reduced in some mixtures but increased in others. The results suggest that nutrient enrichment may alter the competitive balance between the four lichen species and this may be a factor determining their relative abundance on rock surfaces in South Gwynedd.
In South Gwynedd, Wales, U.K., the calcicole lichen Xanthoria parietina occurs not only on alkaline substrates at inland sites but also on siliceous rock at coastal martimie sites while the calcifuge species Parmelia saxatilis occurs only at inland sites and on slate rocks. Samples of maritime and inland slate did not differ significantly in their calcium or magnesium content. Thalli of X. parietina on pieces of slate did not survive when transplanted from maritime rocks to a site inland. Thalli of maritime X. parietina and P. saxatilis on slate were then transplanted to a site inland and were treated at intervals during 1 year either with calcium carbonate applied as a thick paste or a 0.25 mM solution of calcium chloride. Treatment of X. parietina with calcium carbonate enabled the thalli to survive and grow. However, addition of calcium carbonate to P. saxatilis resulted in low growth rates and fragmentation of the centres of the thalli. The calcium chloride solution had no statistically significant effects on the growth of either species. In addition, thalli of both species were treated with calcium or magnesium carbonates or wetted with an alkaline buffer at intervals over 12-14 months. Thalli of X. parietina survived and grew rapidly when treated with either carbonate but the growth of the buffer-treated thalli gradually declined over the experimental period. Thalli of P. saxatilis fragmented and disappeared after 8-10 months after treatment with either carbonate but normal growth occurred in the buffer treatment. Xanthoria parietina may occur on siliceous maritime rocks at the site because of the presence of calcium or magnesium in sea spray combined with the spray’s alkaline pH. By contrast, P. saxatilis may be confined to siliceous rocks inland because the thalli grow poorly in the presence of calcium and magnesium.
To field test the hypothesis that lichen thalli can use environmental sources of carbon, solutions of ribitol, arabitol and mannitol were added to intact thalli of Xanthoparmelia conspersa (Ach.) Hale and a yellow species of Rhizocarpon (Rhizocarpon Ram. Em. Th. Fr. subgenus Rhizocarpon). In addition, ribitol and an arabitol/mannitol mixture were added to the marginal hypothalli of Rhizocarpon thalli after removal of the areolae. Carbohydrates were added at the beginning of 2- or 3-month growth periods for up to 15 months at concentrations approximately three times the levels estimated to be in the thalli. Addition of carbohydrates to intact thalli of both species had no effect on total radial growth but addition of mannitol significantly increased growth of X. conspersa thalli in the September/October growth period in one experiment. However, this effect was not repeated in a subsequent experiment in which different concentrations of mannitol were added to intact thalli. Addition of ribitol to hypothalli of Rhizocarpon resulted in significantly increased growth in the first few months of the experiment, growth then declining to levels below that of untreated thalli. The data suggest that although hypothalli of Rhizocarpon may have the ability to utilise exogenous carbohydrates for growth, there was little evidence that intact thalli of either species utilise environmental sources of carbon in the field.
This chapter discusses the substrate factors, specificity, preferences, and their causes and implications with regard to ecology, distribution, and taxonomy of lichens. The substrate's moisture capacity, mineral content, pH, metabolite production, physical texture, and stability are all important as potential limiting factors. The acidity or alkalinity of the substrate can act on lichen thallus in numerous ways. Various minerals and organic substances are in different chemical states under different pH regimes, some substances are toxic under acidic conditions and harmless when deacidified. Lichens growing on sand dunes show distinct correlations with soil pH level. Under experimental conditions, it has been shown that wet lichens are killed between 35°– 46°C, although some seem to be able to survive at temperatures over 70°C when they are dry. The effect of terricolous lichens on the chemistry of the soil can be either detrimental or beneficial to soil fertility. Some lichens are narrowly substrate specific, that is, confined to one or two tree species or a particular rock type, and others are found not only on trees of different kinds but also sometimes on wood, soil, or rock. Lichens often shift between neutral-barked trees and calcareous rock or the shells of molluscs or bone substrates sharing various characters, such as high calcium content and high pH regime. Epiphytic lichens may conceivably harm their phorophyte by blocking lenticels or harboring harmful insects, but this has never been proven to be a widespread or serious effect.
During photosynthetic fixation of ¹⁴C by lichens, ¹⁴C-carbohydrate moves from alga to fungus. If the ¹²C-form of this mobile carbohydrate is added to the external medium, then the ¹⁴C-form is released from the lichen. This observation forms the basis of the, inhibition technique', used to study movement of carbohydrates between symbionts within intact lichen thalli. The effect is specific since ¹⁴C is released from the lichen only if the ¹²C-carbohydrate in the medium is identical or structurally very similar to that moving between the symbionts.
Three lichen species were wetted with distilled water at different frequencies during August 1973 to July 1974. The radial growth rates of Parmelia glabratula ssp. fuliginosa and Physcia orhicularis thalli declined with increased wetting while the radial growth rate of Parmelia conspersa thalli increased with wetting frequency until ten experimental wettings per month but at fifteen wettings per month fell to a value near to the control. In the summer months wetting resulted in a decline in the radial growth of P. glabratula ssp. fuliginosa compared with the control but had little influence on the growth of P. conspersa and Physcia orbicularis. In the winter months, wetting had no significant influence on the radial growth of Parmelia glabratula ssp. fuliginosa, while the radial growth of P. conspersa increased and Physcia orbicularis declined compared with controls. These results are interpreted physiologically and in relation to the aspect distribution of the three lichens on rock surfaces.
The radial growth of samples of thalli of Parmelia glabratula ssp. fuliginosa were measured in situ on a south-facing and a northwest-facing rock surface each month from August 1973 to July 1974. In the periods August to October 1973 and March to July 1974 the radial growth of thalli in the northwest population was greater than in the south population. In the period November 1973 to February 1974 the radial growth of thalli in the south population was greater than in the northwest population. A physiological basis for the differences in seasonal growth in the two populations was suggested. The mean annual radial growth rate (in units of mm/year) was not significantly different in the two populations. However, the variability in radial growth rate between thalli was signifiacntly larger in the northwest than in the south population. These results may be explained by genetic difference between the populations and environmental differences between the rock surfaces.
1.1. Gaucous-winged gulss, Laurs glaucescens, were acclimated sequentially to fresh water, sea water for periods of 1–2 months. Sodium, K and Cl concentrations in the plasma (no K values), cloacal fluid and NaCl-induced salt-gland secretion were determined (spontaneous salt-gland secretion was analyzed when observed), and body weight and hematocrit were recorded weekly.2.2. Plasma Na concentration was lower in fresh-water birds than in birds acclimated to sea water. Increased salinity of the drinking water had no further effect. Chloride concentration was the same in birds on all drinking water regimes.3.3. In only 12 of 331 cloanal fluid samples was Na hypertonic to plasma; in only 35 of 336 samples was Cl hypertonic.4.4. Cloanal retention of fluid lowered its Na and Cl but increased (or did not change) K concentration.5.5. In NaCl-induced salt-gland secretion Na and Cl concentration were higher in sea water than in fresh-water-acclimated gulls, but further increase in drinking water concentration did not enhance this effect; K concentration of sea-water-adapted birds was twice that of fresh-water birds. The Na : K ratio in fresh-water birds was 24 : 1, 12 : 1 in sea-water birds.6.6. Hypertonic spontaneous salt-gland secretion was observed in gulls drinking fresh water to sea water. Ion concentration increased as drinking-water concentration increased, but Na and Cl were not always of similar concentration as in NaCl-induced secretion.7.7. Body weight and hematocrit were lower in gulls adapted to sea water than in fresh-water birds.8.8. These data further suggest that a major portion of ingested. Na and K may be extrarenally excreted even in the absence of imposed osmotic stress and that the cation concentration in the salt-gland secretion is dependent upon the magnitude of the osmotic stress.
Nutrient requirements and utilization of nutrients: Lichens
- Ahmadjian
Lichen communities in the British Isles: A preliminary conspectus
- James
Nutritional aspects of marine and maritime lichen ecology
- Fletcher
Formation and composition of urine
- Sykes