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Dissertations / Theses on the topic 'Lichens'

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Published: 4 June 2021
Last updated: 29 July 2024

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1

Johansson, Per. "Effects of habitat conditions and disturbance on lichen diversity : studies on lichen communities in nemoral, boreal and grassland ecosystems /." Uppsala : Dept. of Conservation Biology, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200606.pdf.

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2

Denoeud-Valdeyron, Marie-Laure. "Les lichens, bioindicateurs de pollution atmospherique : application aux alentours de l'usine roquette a lestrem." Lille 2, 1992. http://www.theses.fr/1992LIL2P020.

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3

MATHEY, ANNICK. "De in situ lichenum investigatione de l'analyse in situ des lichens." Paris 6, 1987. http://www.theses.fr/1987PA066744.

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Le but de l'etude est de montrer, a partir d'exemples qu'il est possible de reunir des informations sur une plante (morphologie, anatomie, chimie et ecologie) sans creation d'artefact et de remplacer des donnees subjectives par des donnees mesurables, c'est-a-dire reproductibles. Les lichens constituent un modele biologique
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4

Chu, Fung Joanna. "Ecology of supralittoral lichens on Hong Kong rocky shores /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18735526.

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5

Högnabba, Filip. "Phylogenetic studies of cyanobacterial lichens /." Helsinki : Yliopistopaino, 2007. http://ethesis.helsinki.fi.

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6

Carter, Nick. "Bioprotection explored : lichens on limestone." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396154.

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7

Hogan, Erika. "Nitrogen-phosphorus relationships in lichens." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10906/.

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Nitrogen enrichment promotes phosphomonoesterase (PME) activity in the common heathland lichen Cladonia portentosa. This is associated with a marked increase in thallus N:P mass ratio and significant up-regulation of inorganic phosphate uptake capacity, evidencing a shift from N-limited to P-limited growth. Phosphomonoesterase activity in C. portentosa responds rapidly to change in N deposition load, with a significant increase in activity recorded within 6 months of transplantation from a low-N to high-N site. The location of PME activity in C. portentosa was revealed using a fluorescent marker and was found to be concentrated on both the outer and inner surfaces of the hollow ‘tube-like’ thallus branches. Activity appeared to be associated exclusively with the mycobiont and was located within the hyphal-lumina, consistent with a membrane bound ecto-enzyme. High PME activity in axenic mycobiont cultures of C. portentosa provided further evidence of a fungal location and confirmed that rates of activity in this lichen are amongst the highest reported for any other plant/fungal system in the literature. Different classes of phosphatases were assayed in a range of N2-fixing and non-N2-fixing lichens in an oligotrophic subarctic environment. No relationship was found between the capacities for nitrogenase and PME activities. Maximum rates of PME activity were recorded in fruticose mat-forming lichens which capture nutrients predominantly from atmospheric deposits. 5´ nucleotide phosphodiesterase activity was readily detected in N2-fixing lichens and was particularly high in rhizine-rich regions of foliose terricolous lichen thalli, consistent with the utilisation of organic phosphates from soil and litter sources.
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8

McDaid, Ann. "Chemical characterisation of Irish lichens." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282253.

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9

Caldiz, Mayra S. "Diversity and growth of epiphytic macrolichens in northwestern Patagonian Nothofagus forests /." Alnarp : Swedish University of Agricultural Sciences, 2005. http://diss-epsilon.slu.se/archive/00000831/.

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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005.
Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts, three co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks appendix.
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10

Dahlman, Lena. "Resource aquisition and allocation in lichens." Doctoral thesis, Umeå : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-115.

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11

Lines, Catherine Elizabeth Mary. "Studies in the biology of lichens." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238171.

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12

Girard, François. "Remise en production des pessières à lichens de la forêt boréale commerciale : nutrition et croissance de plants d'épinette noire trois ans après traitements de préparation de terrain /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2004. http://theses.uqac.ca.

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13

Salix, Jessie Lynn. "Lichens and their distribution in Lewis and Clark Caverns State Park." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/salix/SalixJ04.pdf.

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14

Lõhmus, Piret. "Forest lichens and their substrata in Estonia /." Online version, 2005. http://dspace.utlib.ee/dspace/bitstream/10062/918/5/lohmus.pdf.

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15

Smith, Elizabeth. "Carbon accumulating mechanisms in lichens and bryophytes." Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282765.

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16

Ucrospoma, Jara Marisa. "Ramalina (Lichens) en los parques de Lima." Pontificia Universidad Católica del Perú. Centro de Investigación en Geografía Aplicada, 2014. http://repositorio.pucp.edu.pe/index/handle/123456789/119300.

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El presente trabajo consiste en realizar evaluaciones de la calidad de aire, mediante indicadores biológicos, como en el caso de Ramalina, líquen que habita las zonas urbano metropolitana de Lima (Ciudad capital), especialmente las áreas verdes en los distritos de Lince, Jesús María, San Isidro, parte de Pueblo Libre y Barranco. Ramalina vive en forma epifita, es decir, sobre los árboles tanto en cortezas de troncos y ramas. Para realizar la evaluación se colectó líquenes cortícolas en las áreas verdes de los distritos mencionados; luego se realizó cortes morfológicos para observar su estructura interna a nivel de talo y soralias, estas últimas le ayudan a dispersarse vegetativamente debido a la costante humedad existente en estas áreas verdes durante todo el año. Lo interesante del caso es que para Lima Metropolitana se registra sólo un género: de líquen conícola: Ramalina, sobre árboles cultivados, no así encontrándose en los parques de Lima y el Cercado, de aquí que se determine que el aire de esos lugares se encuentran contaminados, porque los líquenes no tienen sistemas de eliminación para sustancias tóxicas como el monóxido de carbono producido por el parque automotor en mal estado, que circula por la ciudad, aparte de las fábricas que emiten gases de sus chimeneas.
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17

Koopmann, Ricarda. "Allelopathic effects of bark phenols on epiphytic lichens." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977662861.

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18

Paul, Alexander. "Manganese as a site factor for epiphytic lichens." Doctoral thesis, [S.l.] : [s.n.], 2005. http://webdoc.sub.gwdg.de/diss/2005/paul.

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19

Wood, Louise. "Photosynthetic characteristics of free-living phycobionts from lichens." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299048.

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20

Lessard, Martine. "Caractérisation des produits naturels odorants retrouvés dans les lichens de genre usnea et bryoria de la région du mont Apica, Québec /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 1990. http://theses.uqac.ca.

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21

Welch, Anthony Richard. "The effect of anthropogenic nutrient addition on the growth and competitive abilities of Parmelia caperata, P. reddenda, P. saxatilis and Xanthoria parietina in Cornwall." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289005.

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22

Hernández, Padrón Consuelo E. "Flora y vegetación liquénica epífita de los sabinares herreños /." Berlin : J. Cramer, 1987. http://catalogue.bnf.fr/ark:/12148/cb39980218f.

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23

Ismed, Friardi. "Phytochimie de lichens du genre Stereocaulon : étude particulière de S. Halei Lamb et S. montagneanum Lamb, deux lichens recoltés en Indonésie." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00737382.

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Des études morphologiques, phylogénétiques et des analyses phytochimiques ont été menées sur neuf espèces de lichens fruticuleux du genre Stereocaulon à partir d'échantillons provenant de zones tropicales (Indonésie, Île de la Réunion) et de zones tempérées (France, Italie). Les divers résultats et la comparaison des observations ont permis de préciser certains éléments pour la classification et la diagnose très délicate de ces lichens et de sélectionner deux espèces pour une analyse plus approfondie de leurs métabolites secondaires. L'étude phytochimique a été conduite sur S. halei et S. montagneanum, qui ont été récolté dans l'île de Sumatra. Parmi la quinzaine de métabolites isolés, certains sont communs à ces deux espèces et correspondent à un depside abondant, l'atranorine et des dérivés mono-aromatiques associés. Des depsidones différencient les deux espèces comme l'acide lobarique et des dérivés dans S. halei, l'acide lobariolcarboxylique étant isolé pour la première fois et caractérisé sous forme de conformères. Dans S. montagneanum, ce sont l'acide stictique et des dérivés qui ont été identifiés. Ces profils métaboliques différents rejoignent les résultats de l'étude phylogénétique qui distingue respectivement S. halei et S. montagneanum dans les sous-genres Aciculisporae et Holostelidium. Malgré des activités inégales, aucun des 6 composés obtenus en quantité suffisante pour des test à visée photoprotective ne montre de résultat remarquable. Certains composés de type mycrosporine ont été caractérisés dans diverses parties du pseudopodétion et pourraient aussi présenter un intérêt pour la compréhension des répartitions métaboliques au sein des lichens tripartites.
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24

Ménard, Thierry. "Etude phytosociologique et écologique des peuplements lichéniques saxicoles calcifuges du sud-est de la France." Aix-Marseille 3, 1997. http://www.theses.fr/1997AIX30088.

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L'etude ecologique et phytosociologique des groupements de lichens saxicoles calcifuges de la partie meridionale du sud-est mediterraneen francais s'est revelee riche d'enseignements. L'analyse de transects par prelevement integral, technique nouvelle en lichenologie, permet l'etude fine des ecotones et la mise en evidence de gradients, en particulier d'humidite et de luminosite. Au point de vue phytosociologique, 145 releves, dont 139 effectues selon la methode du prelevement integral, permettent de distinguer 22 associations, sous-associations ou groupements, dont 8 sont nouveaux, qui se repartissent aux etages supralittoral, adlittoral, thermomediterraneen superieur et mesomediterraneen. Ils sont classes par affinites ecologiques et floristiques et compares avec ceux d'espagne du sud-est et ceux de la region eurosiberienne ; ils montrent de grandes affinites avec les premiers. L'analyse quantitative des principaux facteurs microclimatiques (energie lumineuse, temperature et humidite de l'atmosphere au voisinage des thalles, temperature de la surface des thalles et humidite superficielle du substrat) permet de preciser les exigences ecologiques de 7 peuplements, qui se distinguent surtout du point de vue hydrique et photique. Elle confirme l'importance de la microtopographie et des ecoulements d'eau dans l'etablissement de peuplements licheniques varies. La dynamique de l'installation des peuplements est basee sur la comparaison de placettes entierement denudees par prelevement integral et relevees a nouveau dix ans apres. L'installation des lichens, relativement lente, est precedee par celle de colonies de cyanobacteries. Les modalites de la colonisation des substrats vierges sont variees ; en particulier, les groupements subhydrophiles s'installent bien plus rapidement que les groupements non soumis a des ecoulements. L'examen de roches mises a nu par incendie apporte un complement d'information.
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25

Dahl, Wivecke. "Contribution à l'étude des métabolites secondaires chez les lichens fructiculeux Cladina stellaris et Cladina rangiferina /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2003. http://theses.uqac.ca.

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26

Lättman, Håkan. "Description of spatial and temporal distributions of epiphytic lichens." Licentiate thesis, Linköping University, Linköping University, Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11561.

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Lichens are, in most cases, sensitive to anthropogenic factors such as air pollution, global warming, forestry and fragmentation. Two studies are included in this thesis. The first is an evaluation of the importance of old oak for the rare epiphytic lichen Cliostomum corrugatum (Ach.) Fr. This study analysed whether C. corrugatum was limited by dispersal or restricted to tree stands with an unbroken continuity or the substrate old oaks. The results provide evidence that the investigated five populations in Östergötland, Sweden, of C. corrugatum exhibit substantial gene flow, an effective dispersal and a small genetic variation between the sites. Most of the genetic variation was within the populations. Thus, C. corrugatum is more dependent of the substrate old oaks, rather than limited by dispersal. The second study investigated possible range shift of some common macrolichens, due to global warming, from 64 sites in southern Sweden comparing the two years 1986 and 2003. The centroid of three lichen species had moved a significant distance, all in a north east direction: Hypogymnia physodes (L.) Nyl. and Vulpicida pinastri (Scop.) J.-E. Mattsson and M. J. Lai on the tree species Juniperus communis L. (50 and 151 km, respectively) and H. physodes on Pinus sylvestris L. (41 km). Considering also the non-significant cases, there is strong evidence for a prevailing NE direction of centroid movement.

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27

Lättman, Håkan. "Description of spatial and temporal distributions of epiphytic lichens /." Linköping : [Department of Physics, Chemistry and Biology], Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11561.

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28

Rönnqvist, Marie. "Long-term effects of nitrogen deposition on epiphytic lichens." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-72677.

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The main aim of this study was to analyse the long-term effects on epiphytic lichen dry mass development, diversity and community structure after exposure to a simulated nitrogen deposition gradient. A whole tree experiment was set up in a boreal forest in the County of Västerbotten in Sweden, whereby 15 trees were artificially irrigated and nitrogen fertilized during seven consecutive years (2006-2012). The treatments were equal to an additional deposition of 0.6, 6, 12.5, 25 and 50 kg N ha-1 yr-1. Branches from the trees were collected in October 2012 and the lichen material was harvested and further analysed during the spring 2013. The results from this study showed that the lichens were directly affected by the long-term increased nitrogen deposition. Generally, lichen dry mass and species richness declined at high nitrogen loads and the initial positive effects of low nitrogen loads reported in a preceding study had thus depressed with time. The results from this study also showed that the composition of the lichen community changed benefitting nitrogen-tolerant species, probably not because of competition but more likely because of nitrogen-sensitive species disappearance. This study strongly indicates that it takes more than a few years to detect changes in lichen communities exposed to enhanced nitrogen loads. In addition low concentrations seem to have a cumulative impact. Consequently, this study stresses the importance of also considering the cumulative effect of low nitrogen loads when determining critical values. The critical load for lichen communities in boreal forests might be below 6 kg N ha-1 yr-1.
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29

Chu, Fung Joanna, and 朱鳳. "Ecology of supralittoral lichens on Hong Kong rocky shores." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31235712.

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30

Olsson, Therese. "Morphological traits in hair lichens affect their water storage." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-94897.

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The aim with this study was to develop a method to estimate total area of hair lichens and to compare morphological traits and water storage in them. Hair lichens are an important component of the epiphytic flora in boreal forests. Their growth is primarily regulated by available water, and light when hydrated. Lichens have no active mechanism to regulate their water content and their water holding capacity (WHC, mg H2O/cm2) is thus an important factor for how long they remain wet and metabolically active. In this study, the water uptake and loss in five hair lichens (Alectoria sarmentosa, three Bryoria spp. and Usnea dasypoga) were compared. Their area were estimated by combining photography, scanning and a computer programme that estimates the area of objects. Total area overlap of individual branches was calculated for each species, to estimate total area of the lichen. WHC and specific thallus mass (STM) (mg DM/cm2) of the lichens were calculated. Bryoria spp. had a significantly lower STM compared to U. dasypoga and A. sarmentosa, due to its thinner branches and higher branch density. Bryoria also had a lower WHC compared to A. sarmentosa, promoting a rapid uptake and loss of water. All species had a significant relationship between STM and WHC, above a 1:1 line for all species except U. dasypoga. The lower relationship in U. dasypoga is explained by its less developed branching in combination with its thick branches.
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31

Lättman, Håkan. "Studies on spatial and temporal distributions of epiphytic lichens." Doctoral thesis, Linköpings universitet, Ekologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81433.

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Lichens are an important group of organisms in terms of environmental issues, conservation biology and biodiversity, principally due to their sensitivity to changes in their environment. Therefore it is important that we develop our understanding of the factors that affect lichen distribution. In this thesis, both spatial and temporal distributions of epiphytic lichens at different scales have been studied in southern Sweden. Generation time of the red-listed lichen Cliostomum corrugatum was examined using Bjärka-Säby as the study site. The results showed that the average age of an individual of C. corrugatum is 25–30 years at the onset of spore production. The rarity of C. corrugatum was also examined. DNA analysis of an intron from 85 samples, collected at five sites in Östergötland, yielded 11 haplotypes. Results from coalescent analysis, mantel test and AMOVA indicated that C. corrugatum have a high ability to disperse. The study concluded that its rarity is most likely connected with the low amount of available habitat, old Quercus robur. The changes in the distribution of epiphytic lichens in southern Sweden, between 1986 and 2003, were also compared. For each year a centroid was calculated on all combinations of tree and lichen species. The three significant cases showed that the centroid movement pointed toward a north-east or north-north-east direction. Finally differences in species richness and cover of lichens on large Q. robur were examined between urban and rural environment. The results demonstrated that species number and percent cover was significantly higher on oaks standing rural compared to oaks standing urban. Effects of urban sprawl showed a decline in species richness and cover with increasing age of the surrounding buildings.

In the electronic version of this dissertation the Södertörn series Södertörn Doctoral Dissertation 72, ISSN 1652–7399, has been removed.

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32

Rivaux, Emmanuel. "Les lichens : généralités, rôle comme bioindicateurs de la pollution." Paris 5, 1998. http://www.theses.fr/1998PA05P039.

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33

DORGELO, JAN. "La determination matricielle. Application a la systematique des lichens." Reims, 1991. http://www.theses.fr/1991REIMS007.

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La determination d'echantillons a-typiques, ou appartenant a des groupes difficiles, au moyen des flores dichotomiques habituelles conduit generalement a des erreurs ou impasses. L'auteur propose une determination assistee par ordinateur au moyen d'un logiciel original fonctionnant sur i. B. M. Pc ou compatible. Les programmes comparent le specimen avec tous les taxa contenus dans une matrice taxa/caracteres et propose des noms par un classique calcul statistique de ressemblance. Les noms trouves sont generalement valables, meme quand l'echantillon est tres a-typique ou que l'utilisateur a fait un certain nombre d'erreurs. Il s'est avere, en faisant une application sur les lichens crustaces steriles, que les especes decrites ne sont souvent pas suffisamment significatives et que la comparaison d'un specimen doit etre faite par rapport a des individus entierement decrits. De ce fait, la notion d'espece merite d'etre reconsideree
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34

Caruso, Alexandro. "Lichen diversity on stems, slash, and stumps in managed boreal forests : impact of whole-tree harvest /." Uppsala : Swedish University of Agricultural Sciences, 2008. http://diss-epsilon.slu.se/archive/00001675/.

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Thesis (doctoral)--Swedish University of Agricultural Sciences, 2008.
Includes reprints of four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks reprints of four papers and manuscripts.
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35

Semadi, Ammar. "Effets de la pollution atmosphérique (pollution globale, fluorée et plombique) sur la végétation dans la région de Annaba (Algérie)." Paris 6, 1989. http://www.theses.fr/1989PA066455.

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La région de Annaba (Est de l'Algérie) est soumise à une pollution atmosphérique intense et variée. L'utilisation des végétaux et notamment des lichens comme indicateurs biologiques a permis de préciser l'impact de la pollution globale, de la pollution fluorée et de la pollution plombique autour de Annaba. Ces trois aspects sont développés après la présentation des facteurs écologiques de cette région. L'observation des nécroses sur les feuilles de plusieurs espèces phanérogamiques et l'étude de la répartition des lichens ont permis d'établir une zonation de la pollution atmosphérique globale. L'accumulation du fluor chez les végétaux supérieurs et chez les lichens a été utilisée pour réaliser la cartographie de la pollution fluorée avec quatre zones d'isopollution autour de l'agglomération de Annaba. Enfin l'impact de la pollution plombique d'origine automobile a pu être précisé à partir de transects et de transplantation de lichens effectues de part et d'autre de trois principaux axes routiers desservant la ville de Annaba
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36

Downward, Kenneth. "Relationships between surface crusts and erosion in the Tabernas Badlands, Almeria, S.E. Spain." Thesis, University of Wolverhampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325975.

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37

Forbes, PBC, M. Thanjekwayo, JO Okokwo, M. Sekhula, and C. Zvinowanda. "Lichens as biomonitors for manganese and lead in Pretoria, South Africa." Fresenius Environmental Bulletin, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001756.

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Abstract Parmotrema austrosinense (Zahlbr.) Hale lichens were collected from the Pretoria central business district (CBD), as well as three sites to the east of Pretoria; the National Botanical Gardens, the CSIR campus and the suburb of Lynnwood, with the aim of utilising these lichens as biomonitors of air quality to determine the effects of the phasing out of leaded petrol and the simultaneous introduction of manganese anti-knock additives to fuel in South Africa. In addition to lichens, roadside dust and soil samples were collected from the CBD and CSIR campus, and all samples were analysed by flame atomic absorption spectrometry after acid digestion. There was no significant difference (95 % confidence) between the Mn content of lichens from all sampling sites (overall average of 97.1 ± 39.1 μg.g-1, n= 28), which was most likely due to an even suspension of Mn-containing particles arising from soil dust. Additional contributions to Mn loading as a result of vehicle emissions were currently not evident. For all non-CBD sites, higher Pb levels were found in lichens which were nearer to busy roads, suggesting an historical impact by vehicular emissions of Pb arising from leaded petrol usage. The Pb concentrations in lichens found in the CBD (average of 181.1 ± 98.0 μg.g-1, n=10) were significantly higher (95 % confidence limits) than those of lichens growing outside of the CBD area (average of 41.5 ± 36.4 μg.g-1, n=18), and the Pb levels were higher than those of Mn, which was contrary to that found in sites outside the CBD.
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38

Hesse, Volker. "Epiphytic lichen diversity and its dependence on chemical site factors in differently elevated dieback-affected spruce stands of the Harz Mountains /." Berlin : J. Cramer, 2002. http://catalogue.bnf.fr/ark:/12148/cb41308907z.

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39

Dailey, Rebecca N. "Toxicity of Xanthoparmelia chlorochroa and the lichen substance (+)-usnic acid in ruminants." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1798967551&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.

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Signoret, Jonathan Müller Serge. "Etude de la qualité de l'air en Lorraine-Nord par les lichens contribution en tant que bioindicateurs écologiques, bioaccumulateurs d'éléments chimiques et biomarqueurs du stress oxydant /." Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2002/Signoret.Jonathan.SMZ0213.pdf.

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41

Jackson, Heather Bird. "Distribution of chemistry and sexual fecundity in the lichenized-fungi, Xanthoparmelia cumberlandia and Xanthoparmelia coloradon︠sis on Boulder Mountain, Aquarius Plateau, UT /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd623.pdf.

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42

Suija, Ave. "Lichens and lichenicolous fungi in estonia: diversity, distribution patterns, taxonomy /." Online version, 2005. http://dspace.utlib.ee/dspace/bitstream/10062/810/5/suija.pdf.

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43

Snäll, Tord. "Distribution Patterns and Metapopulation Dynamics of Epiphytic Mosses and Lichens." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3904.

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This thesis examines the relative importance of local conditions, dispersal and dynamics of the trees on epiphyte distribution patterns and colonization-extinction dynamics. Study species are the mosses Orthotrichum speciosum and O. obtusifolium, and the red-listed Neckera pennata. The thesis also includes an attempt to parameterize a model for a lichen metapopulation (Lobaria pulmonaria) in a dynamic landscape, based on only presence/absence data of the epiphyte and its host trees.

The results show that epiphyte colonization of trees is affected by both local conditions, and by connectivity to occupied trees. The positive effect of connectivity, implying a restricted dispersal range, was established by both demographic and genetic studies. The important local conditions were tree diameter and vitality, and shade. Local extinctions from trees occurred among small trees with low local epiphyte abundance, but more often, were the results of tree fall.

The observed importance of connectivity on epiphyte colonization agrees with the assumptions of the classic metapopulation model. However, the classic metapopulation model assumes that the landscape is static, and that local extinctions occur for stochastic reasons. The dynamics of epiphytes are different. A new conceptual model is therefore suggested, the patch-tracking metapopulation model. It differs from the classic metapopulation model in that it includes dynamics of the patches, and in that local extinctions only occur as patches are destroyed.

Simulations of the dynamics of N. pennata showed that its future metapopulation size will be overestimated unless the dynamics of the trees are accounted for. The simulation results further suggest that the dynamics of N. pennata can be characterised by the patch-tracking metapopulation model.

The attempt to parameterize the L. pulmonaria metapopulation model showed that more information are required for rigorous parameterization, preferably of the past historic fire regime.

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44

Rudolphi, Jörgen. "Bryophytes, lichens and dead wood in young managed boreal forests /." Uppsala : Dept. of Ecology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200788.pdf.

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45

Snäll, Tord. "Distribution patterns and metapopulation dynamics of epiphytic mosses and lichens /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3904.

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46

McIlroy, de la Rosa John Patrick. "The contradictory role of lichens in the weathering of limestone." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602500.

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Experimental evidence suggests that coverage by certain lichens may actively reduce the rate of calcium loss from limestone surfaces subject to natural dissolution, through shielding by the thallus and the binding and waterproofing of the rock surface and subsurface by fungal hyphae. However, the subsequent decay of hyphae, induced by changes in microenvironmental conditions, necrosis, parasitism or the natural physiological traits of particular lichen species, may expose a chemically and physically weakened substrate to dissolution, triggering relatively rapid weathering-related calcium loss and surface lowering . Consequently, certain crustose and endolithic lichens may induce a period of surface stability throughout the course of their lifespan, followed by a phase of instability and rapid episodic microtopographical evolution after their death and decay. A series of conceptual models is proposed to illustrate this idea over short (single lichen lifespan) and long (multiple lichen lifespans) timescales. The models suggest that the microscale biogeomorphological system of lichen-rock interaction is underpinned by non-linear dynamical system theory as it exhibits dynamical instability and is consequently difficult to predict over a long timescale. Dominance by the conditions of net biodeterioration or net bioprotection may be altered by changes in lichen species or in environmental conditions over time.
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47

Muofhe, Mmboneni Leonard. "Lichens as air pollution assays on the Western Cape coast." Bachelor's thesis, University of Cape Town, 1994. http://hdl.handle.net/11427/26102.

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A pollution survey was done in Milnerton industrial area along three transects, the coastal road, the R27 road, and the N7 road. In this project lichens were used as pollution monitors and their availability, abundance and percentage cover were used to estimate the level of pollution. Lichen specimens were collected from St. James, which is far from the pollution source and put in the vicinity of the Caltex oil refinery for four month after which they were analysed for their fluorescence and chlorophyll content. In all transects, lichen species richness and percentage cover increased with distance from the oil refinery, suggesting that indeed lichens are sensitive to pollution and are therefore good air pollution bio-monitors. The fruticose growth forms especially Teloschistes and Usnea were shown in this study to be the most sensitive to pollution because none of them was recorded close to the oil refinery. Photosynthetic pigment analyses revealed that Parmelia and Xanthoria are affected differently by pollution. Parmelia showed chlorophyll a and b injury under high pollution conditions while Xanthoria showed high carotenoid injury. The results of this study indicate that the atmosphere in the Milnerton industrial area is heavily polluted, with the Caltex oil refinery being the main pollution source.
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48

Carpentier, Claudia. "Investigations phytochimiques de lichens soumis au stress de la nordicité." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27345.

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Les lichens produisent une variété de métabolites secondaires de défense en réponse à un stimulus externe (intensité lumineuse, prédation, pathogène, conditions climatiques, etc.) afin de protéger les partenaires symbiotiques. Plusieurs activités biologiques sont associées à ces métabolites de défense : antitumorale, antipyrétique, anti-inflammatoire, antioxydante, antimycobactérienne, antimicrobienne et analgésique. Les décoctions de lichens étaient d'ailleurs utilisées en médecine traditionnelle pour traiter les maladies respiratoires (irritation de la gorge, toux, asthme et tuberculose), le diabète et les infections intestinales. L'objectif du projet consiste à isoler et identifier de nouveaux produits naturels bioactifs issus des lichens du grand du nord du Québec qui vivent des stress uniques au monde. La diversité moléculaire des lichens Stereocaulon paschale et Cladonia stellaris provenant de la région d'Umiujaq a été étudiée. Pour ce faire, des tests in vitro indicatifs de l'inhibition des étapes majeures de la carcinogenèse (initiation, promotion et progression) et anti-inflammatoires ont été réalisés lors du criblage biologique des extraits bruts pour identifier de nouveaux agents chimiopréventifs du cancer. Afin de localiser les composés actifs directement sur le chromatogramme, les extraits bruts ont été microfractionnés par chromatographie liquide à haute performance (HPLC), puis les fractions ont été soumises aux tests biologiques. Parallèlement, un premier criblage chimique des extraits bruts a été fait par HPLC-UV-TOF-HRMS. L'isolation à l'échelle du milligramme des produits naturels a ensuite été effectuée par chromatographie liquide à moyenne pression (MPLC). Puis, la structure des composés purs a été élucidée par une variété de méthodes spectroscopiques telles que la RMN, HRMS, IR, etc.
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49

Le, Pogam-Alluard Pierre. "Analyses de lichens par spectrométrie de masse : déréplication et histolocalisation." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S056/document.

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Les lichens, organismes symbiotiques associant un champignon et un partenaire photosynthétique (algue verte et/ou cyanobactérie), sont caractérisés par la biosynthèse de métabolites secondaires uniques dotés de bioactivités variées. Pour valoriser au mieux cette ressource privilégiée, des méthodes innovantes de spectrométrie de masse ont été développées dans le but de minimiser la préparation de l’échantillon et la durée des analyses. Deux techniques de spectrométrie de masse ont été évaluées en ce sens : le DART-MS et le LDI-MS. L’apport de chacune de ces deux méthodes a pu être établi sur un large panel de lichens, représentant une part importante de l’espace chimique couvert par ces organismes. Il a été démontré que des profils chimiques complets pouvaient être obtenus respectivement à partir de thalles lichéniques et d’extraits acétoniques totaux. Compte tenu de la très large utilisation de la CCM pour l’analyse chimique de lichens, les possibilités offertes par le couplage de la CCM à l’ionisation electrospray ont également été explorées. Une seconde partie de ces travaux avait pour but de cartographier la distribution des métabolites secondaires au sein du thalle lichénique. À ces fins, des analyses d’imagerie LDI ont été réalisées sur une coupe transversale d’un lichen crustacé modèle : Ophioparma ventosa. Ce lichen a été étudié en phytochimie pour identifier six napthopyranones à partir des apothécies dont quatre nouvelles structures. Les principaux métabolites de ce lichen ont pu être imagés par LDI-MSI avec une résolution spatiale de 50 μm environ. Une corrélation entre la distribution des molécules et leur rôle écologique présumé permet d’avancer des hypothèses d’écologie chimique. Des approches conjointes reliant histolocalisation et étude génétique des partenaires de la symbiose ont été entreprises. La recherche des gènes de la biosynthèse de la mycosporine sérinol chez les symbiontes isolés de Lichina pygmaea par microdissection capture laser a été initiée en ce sens. D’autres approches innovantes comme l’analyse cristallographique par diffraction de poudre par les rayons X sont également abordées dans ce document articulé autour de six publications issues de ce travail et de deux articles en cours de soumission
Lichens are self-sustaining symbiotic partnerships comprising a fungus associated with a green alga and/or a cyanobacteria. This consortium produces unique secondary metabolites that are endowed with various biological activities. To harness this privileged chemodiversity, innovative mass spectrometry techniques were developed in the course of this study to accelerate the dereplicative holdup through both a minimal sample preparation and a decrease of the time of analysis. Two approaches were considered during this work: DART-MS and LDI-MS and their adequacy for lichen dereplication was assessed on a vast array of samples encompassing a wide range of metabolites. Both of them facilitated complete chemical profiles, respectively from unprocessed lichen material and crude acetone extracts. Since TLC still enjoys a wide-spread popularity among lichenologists, the advantages offered by TLC-ESI-MS hyphenation were evaluated as well. A second part of this manuscript focused on the histolocalization of lichen metabolites. For this purpose, LDI mass spectrometry imaging studies were undertaken on the crustose lichen Ophioparma ventosa. The phytochemical investigation of this species afforded the isolation of six naphthopyranones from its apothecia, four of them being new molecules. LDI-MSI revealed the distribution patterns of all the main metabolites of this lichen, reaching a spatial resolution of 50 μm. Most interestingly, the distribution pattern of imaged metabolites within the thallus is highly organized and is related to their ecological relevance. Joint strategies combining histolocalization and genetic investigation of lichen symbionts separated using laser capture microdissection were also considered. As such, an investigation of the biosynthesis of mycosporine serinol within Lichina pygmaea dissociated symbionts was initiated. Further analytical strategies such as X-ray powder diffraction are introduced in this thesis that contains six publications and two drafts to be submitted
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Gadéa, Alice. "Lichens et gastéropodes du Subantartique : écologie chimique et relations trophiques." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B041/document.

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Les interactions « lichen-lichénophage » sont médiées par la présence de métabolites au sein des lichens qui peuvent influer sur les préférences alimentaires des lichénophages. Dans le contexte environnemental du Subantarctique, à faible biodiversité animale et « végétale », une étonnante richesse lichénique a contribué au succès de l’unique Gastéropode terrestre endémique, Notodiscus hookeri. Pour mieux comprendre les mécanismes en jeu, nous avons analysé les préférences alimentaires de cet escargot lichénophage et tenté de cibler les traits-clés des lichens qui modulent l’interaction trophique. À partir d’observations et de prélèvements réalisés sur l’île de la Possession (Archipel Crozet, Terres Australes et Antarctiques Françaises), deux étapes décisives de l’interaction ont été étudiées : (i) le comportement alimentaire de l’escargot en situation de choix nutritionnel, (ii) sa réponse gustative face à des métabolites en situation de non choix. Le broutage préférentiel de certaines parties de lichen a été confronté à l’analyse de la combinaison entre la teneur des métabolites secondaires et celle des métabolites primaires. La localisation des métabolites au sein du thalle de trois espèces lichéniques fréquentes sur l’île et consommées par l’escargot (Argopsis friesiana, Pseudocyphellaria crocata et Usnea taylorii) a été effectuée par l’intermédiaire de techniques chromatographiques et spectrométriques (LC-DAD-MS, GC-MS, microdissection couplée à la LC-DAD-MS, DART-MS) ainsi que par des techniques d’imagerie couplées à la spectrométrie de masse ((MA)LDI-MS). N. hookeri se révèle être une espèce généraliste et opportuniste qui se nourrit de la majorité des lichens auxquels il est confronté. Cependant, il opère des choix en se nourrissant des parties ayant une valeur nutritive élevée et ce, en dépit de la présence de métabolites secondaires potentiellement répulsifs. Plusieurs mécanismes permettant à l’escargot de contrer la toxicité de certains métabolites ont également été décrits dans ce travail. Les choix alimentaires de N. hookeri s’avèrent par conséquent répondre à un compromis entre le bénéfice d’absorption de métabolites appétents à forte valeur nutritive et le coût physiologique (détoxication, clivage, excrétion) engendré par l’ingestion de métabolites répulsifs. En conclusion, trois paramètres-clés au moins seraient à prendre en compte lors des futures études d’interactions entre lichens et lichénophages : il s’agit de la nature et de la teneur des métabolites secondaires, de la teneur en azote ainsi que de la quantité de sucres et de polyols. Les techniques d’imagerie ont fourni une voie nouvelle et prometteuse pour cibler les dégâts opérés par un phytophage. En effet, cette approche permet de mieux apprécier la distribution hétérogène au sein du thalle entre les métabolites. Pour cet escargot terrestre, les ratios de composés « appétents/inappétents » semblent jouer un rôle majeur dans la sélection de nourriture
Lichen-lichenivore interactions are mediated by the presence of metabolites in lichens, which may impact lichenivore food preferences. In the environmental context of the Subantarctic, with a low animal and “plant” biodiversity, the surprising lichen flora contributed to the success of a the only endemic subantarctic land Gastropod, Notodiscus hookeri. To better understand the snail-lichen interactions, we analyzed the food preferences of this lichenivore snail and tried to pinpoint key lichen traits modulating the trophic interaction. From observations and samplings realized on Possession Island (Crozet Archipelago, Terres Australes et Antarctiques Françaises), two decisive stages of the interaction were studied: (i) the snail feeding behavior in situation of nutritional choice, (ii) its gustatory response when facing isolated metabolites in no-choice situations. Preferential grazing of some lichen parts was linked to both secondary and primary metabolites concentrations. Intrathalline localization of metabolites was performed in three lichen species consumed by the snail and widespread on Possession Island (Argopsis friesiana, Pseudocyphellaria crocata and Usnea taylorii), using chromatographic and spectrometric techniques (LC-DAD-MS, GC-MS, microdissection coupled to LC-DAD-MS, DART-MS) and imaging mass spectrometry ((MA)LDI-MS). N. hookeri appears to be a generalist and opportunistic gastropod, feeding on most lichen species encountered. However, it is able to discriminate between lichen parts, preferentially grazing on parts with the highest nutrient value, in spite of the presence of potential deterrent secondary metabolites. We described several mechanisms helping snails to overcome the toxicity of some lichen metabolites. Snail feeding choices result in trade-off between benefits of absorbing appetent metabolites of high nutritive value and the cost of physiological processes (detoxification, cleavage and excretion) caused by the ingestion of deterrent metabolites. To conclude, three main key parameters might be relevant in future to study the interactions between lichens and lichenivores. They correspond to the nature, the histolocalisation and the content of secondary metabolites balanced by the amount of nitrogen along with sugars and polyols. Imaging techniques have provided a new and promising way to visualize the heterogeneous distribution within the thallus between these metabolites. The ratios of appetent/non appetent compounds are likely to play a major role in food selection by this land snail
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