Dissertations / Theses on the topic 'Cryptogams'

The aim of the present study was to determine the potential impact of intertidal grazers on the distribution of macro algae on the south coast of South Africa. Particular attention was paid to the large patellid limpet, Patella oculus, which is found thoughout the intertidal zone. Studies of gut contents revealed that Patella oculus was capable of ingesting not only the thallus of foliose (eg. Ulva spp.) and encrusting coralline macroalgae, but also spores and diatoms. The inclusion of these relatively small particles in the diet was surprising, as electron micrographs of the radula of P.oculus revealed that it is typically docoglossan in structure. Such radulae are thought to be poorly suited for collecting small food particles. Sand made up a significantly higher proportion of the gut contents than other particles at all shore heights, which suggests that P.oculus might be capable of excavating the rocky substratum, or of sweeping up sand, while searching for food. Analysis of the gut contents of other local herbivorous molluscs, was also carried out. These species included the winkles, Oxystele variegata and O.sinensis, and the small pulmonate limpets, Siphonaria concinna, S.capensis, and S.serrata. The guts of all species contained mainly spores and diatoms, although small fragments of Ulva sp. were found. The population structure of Patella oculus was investigated at two sites, Cannon Rocks and Old Woman's River. At Cannon Rocks, mean shell length of low-shore animals was significantly lower than that of both mid- and high-shore animals, while at Old Woman's River, no significant difference was found among shore heights. A regression equation for In (shell length) vs In (dry weight) was calculated, and based on length data, the biomass density (g dry mass.m⁻²) of P.oculus at Old Woman's River was estimated. Values ranged from 2.8 on the low- and midshore to 0.37 on the high-shore. A manipulative field experiment was used to determine the impact of mesograzers and macrograzers (such as Patella oculus) on the distribution of intertidal macro algae on the mid- and low-shore at Old Woman's River. Grazers were excluded using mesh cages (mesh size = 3mm), in two separate experiments, one in winter and the other in spring. Percentage cover of macroalgal species and sessile invertebrates was estimated at approximately 6 week intervals for up to 3 months. MANOV A showed that treatments did not significantly affect cover of macroalgae or barnacles during winter. However, towards the end of the spring experiment (midshore only) cover of barnacles and green foliose turfs did increase in those plots from which mesograzers and/or macro grazers were excluded. The failure of the statistical tests to detect significant differences at some time intervals may have been caused by high levels of variation among replicates. This suggests that factors other than grazing are of overriding importance in determining the distribution of local macroalgae. The existence of a possible symbiotic relationship between Patella oculus and the red foliose alga, Gelidium pristoides, was investigated. The availability of various substratum types, including rock, limpet shells, barnacles etc., and the proportion of the total cover of G.pristoides on each, was calculated. It was shown that a significantly higher proportion of the alga grew on limpet shells, although the availability of this substratum type was low. It is thought that the aggressive behaviour of P.oculus prevents all but juvenile Patella longicosta from grazing on its shell, thus providing a refuge from grazing for G.pristoides.

O perifíton é formado por uma complexa comunidade de organismos aderidos a um substrato orgânico ou inorgânico, dos quais as diatomáceas (Bacillariophyta) constituem importante parcela. Mais recentemente inventários florísticos que contemplam as diatomáceas bentônicas em sistemas lóticos vêm incrementando o conhecimento da flora na região Neotropical e Neosubtropical, porém grande parte desses sistemas permanece inexplorado, especialmente em águas oligotróficas, de altitude e de baixo pH. Tais ecossistemas em geral possuem uma flora bastante peculiar, e são importantes referências em termos qualidade de água. Desta forma, o presente estudo teve por objetivos contribuir para o conhecimento da flora de diatomáceas perifíticas do Parque Estadual do Ibitipoca, localizado na serra da Mantiqueira em Minas Gerais. Como resultado, foram identificados 15 gêneros, 18 espécies e duas variedades taxonômicas. Duas novas espécies do gênero Eunotia são propostas e três espécies do gênero Nupela não puderam ser identificadas de acordo com a literatura, sendo provavelmente novas para a ciência. São feitos 16 registros pioneiros para o estado de Minas Gerais, sendo quatro delas primeiras ocorrências em território brasileiro. A composição taxonômica das diatomáceas perifíticas do Parque Estadual do Ibitipoca apresenta semelhanças com a flora de outros ambientes oligo-distróficos já inventariados nos Neotrópicos. Palavras-chave: ambientes continentais, águas oligotróficas, Eunotia, Nupela, taxonomia de criptógamos.
The periphyton is composed by a complex community of organisms adhered to an organic or inorganic substrate, and diatoms (Bacillariophyta) constitute an important part of it. More recent floristic inventories in lotic systems that include benthic diatoms increased the knowledge of the Neosubtropical Neotropical flora for the region, but most environments remains unexplored, especially those with oligotrophic and low pH waters in altitude sites. Such ecosystems in general have a very peculiar flora and are important indicators of water quality. Thus, the present study aimed to contribute to the knowledge of periphytic diatom flora of Ibitipoca State Park, located in the Mantiqueira ridge, in Minas Gerais. As a result, we identified 15 genera, 18 species and two taxonomic varieties. Two new species of Eunotia are proposed and three species of the genus Nupela could not be identified according to the literature, and are probably new to science. Sixteen new records were made for the state of Minas Gerais, including four first occurrences for Brazil. The taxonomic composition of the periphytic diatoms of Ibitipoca State Park share similarities with other oligo-dystrophic environments already surveyed in the Neotropics.

Biodiversity studies have recently focused on incorporating measures of phylogenetic and functional diversity into examinations of community ecology. Functional diversity describes those traits that influence the interaction between a species and the environment, whereas phylogenetic diversity is a more derived measure that represents the evolutionary history of species, and might incorporate information on functional identity, taking into account multiple traits. This thesis examined patterns in cryptogam (bryophyte and lichen) diversity across an elevation gradient to (i) evaluate the interplay between species, phylogenetic, and functional lichen diversity within and between habitats and (ii) link diversity (species and phylogenetic) to bryophyte productivity across environmental gradients. We found that phylogenetic and functional turnover correlate strongly, despite low signal in measured traits. Within and between habitats, different beta diversity indices are driven by different environmental factors, and as such one metric cannot be used as a surrogate for another. By establishing a link between diversity and productivity within bryophytes, we highlight the importance of diversity in regulating biomass production within stressful environments. We also highlight the use of alternative phylogenetic measures as descriptors of the diversity-productivity relationship, as they provide more information on the underlying mechanisms that drive the relationship. Cryptogams are relatively understudied in comparison to their vascular counterparts, and as such the information from this study will provide valuable insights into their community structure and turnover across space.
Les études sur la biodiversité ont récemment mis l'accent sur l'intégration des mesures de diversité phylogénétique et fonctionnelle dans les examens de l'écologie des communautés. La diversité fonctionnelle décrit les traits influençant l'interaction entre une espèce et l'environnement, alors que la diversité phylogénétique est une mesure dérivée représentant l'histoire de l'évolution d'une espèce et peut inclure des renseignements sur l'identité fonctionnelle d'une espèce. J'ai étudié les modèles de diversité des cryptogames (bryophytes et lichens) à travers un gradient d'altitude afin (i) d'examiner les interactions entre la diversité des espèces, la diversité phylogénétique et la diversité fonctionnelle des lichen au sein des habitats et entre eux, et (ii) de relier la diversité (des espèces et phylogénétique) à la productivité des bryophytes à travers les gradients environnementaux. Nous avons constaté que les changements de la composition phylogénétique et fonctionnelle sont fortement corrélés, malgré le faible signal dans les traits mesurés. Puisque les différents indices de diversité bêta sont entrainés par différents facteurs environnementaux au sein des habitats et entre eux, une unité de mesure ne peut être utilisée comme substitut à une autre. En établissant un lien entre la diversité et la productivité au sein des bryophytes, nous soulignons l'importance de la diversité dans la règlementation de la production de biomasse au sein d'environnements stressants. Nous appuyons également l'utilisation de mesures phylogénétiques alternatives comme descripteurs de la relation diversité-productivité, car celles-ci apportent plus d'information sur les mécanismes entrainant cette relation. Puisque les cryptogames sont relativement peu étudiés, cette étude fournit des indications précieuses sur la structure de leur communauté et leur changement de composition à travers l'espace.

Une etude comparative de la structure nucleaire et de la teneur en adn a ete realisee chez 16 especes representatives des principaux phylums de cryptogames photosynthetiques (algues, bryophytes, pteridophytes) afin d'apprecier l'amplitude des variations inter- et intraspecifiques de l'organisation chromatinienne des noyaux interphasiques. Il a ete montre que 15 des 16 especes examinees possedent des noyaux de type diffus (areticule). Seul le codium tomentosum (chlorophycophytes) a des noyaux de type chromomerique. Au sein du type diffus trois sous-types caracterises par differents degres de densite de l'euchromatine diffuse ont pu etre distingues. La taille du genome diploide estimee par microspectrophotometrie a balayage varie de 0,7 pg pour selaginella kraussiana a 3,9 pg pour fontinalis antipyretica. Ces valeurs sont representatives de la faible proportion de chromatine condensee, rencontree dans les noyaux analyses et sont en accord avec les donnees decrites pour des types de texture chromatinienne identique chez les angiospermes. Il n'existe par ailleurs aucune relation entre le contenu en adn specifique et le nombre chromosomique. De meme, l'utilisation des fluorochromes specifiques n'a pas permis de mettre en evidence de difference manifeste dans la composition nucleotidique en bases a-t ou g-c de la chromatine condensee (chromocentres). Au cours du cycle cellulaire etudie plus particulierement sur trois especes (1 bryophyte et 2 algues), des variations mineures de l'organisation nucleaire ont ete detectees qui n'affectent pas de facon profonde le type nucleaire. Celui-ci reste le meme dans tous les territoires meristematiques ou differencies d'une meme plante. Ainsi se trouve verifie pour les cryptogames le caractere specifique de l'organisation nucleaire

Dry grasslands and heathlands are important habitats for biodiversity conservation and host cryptogam soil crusts (CSC) that greatly contribute to ecosystem functioning. This thesis aims at exploring: the terricolous lichen diversity in dry habitats in a human-impacted lowland (Po Plain, N Italy); the compositional patterns of CSC across dry grasslands and heathlands, also accounting for the dynamic stage of the vegetation (pioneer vs mature); the effects of small-scale disturbances on the three main taxa found in cryptogam-rich dry grasslands (vascular plants, lichens, bryophytes); the potential of CSC in delivering the ecosystem service of storing seeds of vascular plants, in the perspective of habitat restoration. Diversity and dynamics were studied by means of vegetation surveys in circular plots, whose number was area-dependent, located along transects in each habitat patch (= 185 plots in 60 grasslands, 114 plots in 22 heathlands). The % cover of each plant, bryophyte and lichen was recorded, with environmental (soil pH and texture, vegetation structure, altitude, bare soil %), disturbance-related (human trampling, cattle and lagomorphs fecal pellets, wild boar scratches) and climate variables (mean annual temperature and precipitation). The composition in lichens and bryophytes was compared among the 3 habitat types (3 groups) and between their dynamic stages (pioneer vs mature, 6 groups) to understand whether it is habitat- and stage-specific by means of NMDS, PERMANOVA and Indicator Species Analysis. Drivers of cover and species richness of the 3 taxa were analyzed for dry grasslands by means of generalized linear models. The seed storing function was studied taking 5 samples of CSC in 4 acidic grassland patches (= 20 samples), each sample taken at the centre of one plot surveyed in the previous spring. The samples were dryed, crumbled on sterile gardening soil in a controlled situation. All the germinated seedlings were identified and counted. Data were analyzed in comparison to data from the donor plots by means of Kruskal-Wallis test and linear regression, considering all the species and then native and non-native species separately . 33 terricolous lichen species were recorded, of which 13 of conservation concern. In spite of the widespread presence of few common species and the generally low species richness, composition differs significantly between the 3 habitat types and between pioneer vs mature heathlands, less markedly between dynamic stages within each grassland type. Three well-characterized assemblages which include many species of conservation concern were found for both lichens and bryophytes. Cryptogam assemblages are influences also by rainfall, soil features and vegetation structure. Increase of soil pH and disturbance by lagomorph fecal pellets have a negative effect on lichens, as well as their interaction (the negative effect of pellets is more evident at the increase of soil pH). Soil pH, fecal pellets and precipitation have a positive effect on bryophytes. Human trampling and fecal pellets have a negative effect on vascular plants, while increase of soil pH has a positive effect. The interaction of soil pH and pellets has an effect opposite than on lichens (the negative effect of pellets is more evident at the decrease of soil pH). CSC are able to store and release vascular plant seeds which are viable and can germinate when placed in proper conditions. The number of species and individuals of vascular plants germinated from CSC is comparable to what recorded in nature in the donor plots. Native species richness was higher, while native species germinated with less individuals than non-native species. These results are useful in addressing conservation towards the management and protection of all the lowland dry habitats, due to the differentiation among the cryptogam assemblages they host and to the presence of several species of conservation concern.
Dry grasslands and heathlands are important habitats for biodiversity conservation and host cryptogam soil crusts (CSC) that greatly contribute to ecosystem functioning. This thesis aims at exploring: the terricolous lichen diversity in dry habitats in a human-impacted lowland (Po Plain, N Italy); the compositional patterns of CSC across dry grasslands and heathlands, also accounting for the dynamic stage of the vegetation (pioneer vs mature); the effects of small-scale disturbances on the three main taxa found in cryptogam-rich dry grasslands (vascular plants, lichens, bryophytes); the potential of CSC in delivering the ecosystem service of storing seeds of vascular plants, in the perspective of habitat restoration. Diversity and dynamics were studied by means of vegetation surveys in circular plots, whose number was area-dependent, located along transects in each habitat patch (= 185 plots in 60 grasslands, 114 plots in 22 heathlands). The % cover of each plant, bryophyte and lichen was recorded, with environmental (soil pH and texture, vegetation structure, altitude, bare soil %), disturbance-related (human trampling, cattle and lagomorphs fecal pellets, wild boar scratches) and climate variables (mean annual temperature and precipitation). The composition in lichens and bryophytes was compared among the 3 habitat types (3 groups) and between their dynamic stages (pioneer vs mature, 6 groups) to understand whether it is habitat- and stage-specific by means of NMDS, PERMANOVA and Indicator Species Analysis. Drivers of cover and species richness of the 3 taxa were analyzed for dry grasslands by means of generalized linear models. The seed storing function was studied taking 5 samples of CSC in 4 acidic grassland patches (= 20 samples), each sample taken at the centre of one plot surveyed in the previous spring. The samples were dryed, crumbled on sterile gardening soil in a controlled situation. All the germinated seedlings were identified and counted. Data were analyzed in comparison to data from the donor plots by means of Kruskal-Wallis test and linear regression, considering all the species and then native and non-native species separately . 33 terricolous lichen species were recorded, of which 13 of conservation concern. In spite of the widespread presence of few common species and the generally low species richness, composition differs significantly between the 3 habitat types and between pioneer vs mature heathlands, less markedly between dynamic stages within each grassland type. Three well-characterized assemblages which include many species of conservation concern were found for both lichens and bryophytes. Cryptogam assemblages are influences also by rainfall, soil features and vegetation structure. Increase of soil pH and disturbance by lagomorph fecal pellets have a negative effect on lichens, as well as their interaction (the negative effect of pellets is more evident at the increase of soil pH). Soil pH, fecal pellets and precipitation have a positive effect on bryophytes. Human trampling and fecal pellets have a negative effect on vascular plants, while increase of soil pH has a positive effect. The interaction of soil pH and pellets has an effect opposite than on lichens (the negative effect of pellets is more evident at the decrease of soil pH). CSC are able to store and release vascular plant seeds which are viable and can germinate when placed in proper conditions. The number of species and individuals of vascular plants germinated from CSC is comparable to what recorded in nature in the donor plots. Native species richness was higher, while native species germinated with less individuals than non-native species. These results are useful in addressing conservation towards the management and protection of all the lowland dry habitats, due to the differentiation among the cryptogam assemblages they host and to the presence of several species of conservation concern.

Internet of things (IoT) is currently on our doorsteps. Numerous domains have beneted from this technology. It ranges from a simple application such as identifying an object up to handling a more complex system. The Radio Frequency IDentication (RFID) is one of the enabling technologies that drive the IoT to its position today. It is small, cheap and does not require any additional power sources. Along with its ubiquitous functionality, this technology enables the positioning of an object within a specic area. Ambient Assisted Living (AAL) is one of the many domains that benet from the IoT. It aims at assisting elderly people in their daily routines by providing new assistive services in smart homes for instance. RFIDs in a smart home come as a great help to an elderly person, for example, to nd an object that they misplaced. However, even with all its benets in simplifying our lives, it is unfortunately double-edged where the advantage that it brings to an object could in turn go against itself. Indeed to be able to help the older adults to locate an object, the system requires certain data in relation to the positioning of the object and its identication. As the passive RFID tag coverage is very small, once its presence is detected, it is dicult to hide it. The ability of this technology in localizing objects gives an opportunity to a third person to take an advantage of the system. In parallel with the persistent and constant need of privacy and secrecy by the users, the objective of this thesis consists of improving the privacy in localizing an object through a new protocol based on the latest version of the RFID second generation passive tag. The proposed protocol must be able to prevent an object from being identied and located by unauthorized parties or a malicious reader. The rst contribution of this work is the assessment of the RFID anti collision management. It is performed through the creation of an OMNET++ framework, modelled and built based on the latest RFID standard developed by GS1 and incorporated by ISO/IEC called Gen2V2 (RFID class 2 Generation 2 Version 2). It is a passive RFID tag that does not require any internal power sources to operate. It communicates using the UHF frequency. The Gen2V2 standard provides a list of cryptographical suites that can be used as a method to authenticate a tag and a reader. This new generation of tags is supported by an alliance of manufacturers called RAIN (RAdio frequency IdenticatioN) that promotes the adoption of the Gen2V2. The anti collision management overall performance is then compared with its theoretical value and four of its cryptographical suites namely PRESENT80, XOR, AES128 and cryptoGPS. Among the performances evaluated within the framework is the number of collisions and the duration required to interrogate a group of tags. Note that an addition of a localization functionality within the framework reveals that exchanged messages through wireless channel prior to the authentication can lead to a malicious localization of an object. To increase the localization privacy within AAL application, we propose therefore a second contribution which is a new localization method that is based on the current Gen2V2 standard exchanges by anonymizing the tag identity.

How long has the extant flora been present in the Antarctic? Glaciological reconstructions propose that most areas in Antarctica were covered by thick ice sheets throughout the Last Glacial Maximum (LGM; ~22-18 kya) as well as previous glaciations, suggesting terrestrial life must have been extremely limited during these periods. In contrast, recent biogeographic and genetic studies support most extant groups of Antarctic terrestrial fauna having survived past glaciations in situ. However, studies on the origin and age of the Antarctic flora remain sparse. Applying population genetic, phylogeographic and divergence time analyses I assessed the global biogeography, origin and age of several abundant Antarctic moss species, including: four Polytrichaceae mosses, characterised by having bipolar distributions, the most common (~45% of species) distribution pattern amongst Antarctic mosses; the globally widespread moss Ceratodon purpureus; the bank-forming moss Chorisodontium aciphyllum, also known for its old sub-fossils in Antarctica and long-term viability from revival experiments; and, lastly, the genus Schistidium, the most species-rich moss genus in Antarctica, including many endemic species. Genetic analyses revealed evidence of long-term (multi-million year) survival of plants in Antarctica (several species of Schistidium, Ceratodon purpureus, and possibly Polytrichum juniperinum). However, evidence for a likely more recent (< 100 ky) arrival of Chorisodontium aciphyllum was also found. Some species revealed multiple separate dispersal events to the Antarctic, suggesting the region may be less isolated for spore-dispersed organisms than previously thought. Evidence for increased genetic diversity in the northern maritime Antarctic compared to other regions point at it including potential refugial areas. Furthermore, genetic patterns revealed geographic features that enable and limit the connectivity of bryophytes globally as well as in Antarctica. This study suggests that, despite the harsh polar climate during glaciation periods, many bryophytes have had a much longer presence in Antarctica than previously thought.

The main aim of this thesis was to study, choose and decribe techniques eligible for cryptography education. A pedagogically appropriate presentation for the selected techniques' principles was to be chosen. Another goal was to create an integrated modular web interface containing a calculator focused on cryptographic operations. The eligibility of techniques was assessed accordingly to the computing processes implied by these techniques and also accordingly to the ability of being presented in an illustrative way. A program simplifying calculations used in symetric and asymetric cryptography was designed and implemented. It disposes of a web interface and one of its parts is focused on steganographic techniques. On the other hand, any pedagogically appropriate presentation interconnecting this program with theoretical findings from this field was not found.

In this study adaptations of bryophytes and lichens to desiccation stress were examined. The aim was to test whether desiccation tolerance in the selected species is constitutive or if desiccation tolerance could be induced by various hardening treatments. In addition, some putative tolerance mechanisms were investigated, including the accumulation of sugars, increase in ROS scavenging systems and other mechanisms e.g. energy dissipating processes. To determine if hardening treatments prior to desiccation stress increased desiccation tolerance, mosses and lichens were partially desiccated or treated with ABA. The effect of hardening treatments on the physiology of the moss Atrichum androgynum and lichens Peltigera polydactyla, Ramalina celastri and Telochistes capensis during a desiccation-rehydration cycle was investigated. Photosynthesis, respiration and chlorophyll fluorescence measurements were used as rapid tools to determine the metabolic activities in these lichens and moss species. In A. androgynum partial desiccation following slow drying at 52% RH increased the rate of recovery of net photosynthesis. Net photosynthesis recovered almost completely following slow drying in the material that was partially dehydrated and/or treated with ABA. This suggests that partial dehydration hardens the moss, and that ABA can fully substitute for partial dehydration. In R celastri and P. polydactyla both partial dehydration and ABA treatments displayed some improvement in desiccation tolerance depending on the duration and severity of stress. The reduction in the re-saturation respiration burst in P. polydactyla, although not quite significant, strongly suggests that hardening increases mycobiont tolerance. However, it is more difficult to establish whether the hardening treatments improve photobiont performance. In the moss A. androgynum ABA treatment increased the rate of recovery of photosynthesis and PSII activity, and also doubled non-photochemical quenching (NPQ). Increased NPQ activity will reduce ROS formation, and may explain in part how ABA hardens the moss to desiccation. In ABA treated, but not untreated mosses, desiccation significantly increased the concentration of soluble sugars in A. androgynum. Sugar accumulation may promote vitrification of the cytoplasm and protect membranes during desiccation. Starch concentrations in freshly collected A. androgynum and R. celastri were only c. 40 and 80 mg g ¯¹ dry mass respectively, and slightly rose during desiccation, but were only slightly affected by ABA pretreatment. ABA did not reduce chlorophyll breakdown during desiccation. In P. polydactyla ABA pretreatment had little effect on any of these parameters. Changes in the activities of the free radical scavenging enzymes ascorbate peroxidase, catalase and superoxide dismutase were measured during wetting and drying cycles in the moss A. androgynum and in the lichens P. polydactyla, R. celastri and T capensis. These species normally grow in the understorey of the Afromontane forest, moist, xeric, and extremely xeric miicrohabitats respectively. In A. androgyum, enzyme activity was measured shortly after collection, after 3 d storage following hardening by partial dehydration and/or 1 h treatment with ABA or distilled water and during desiccation and rehydration. In A. androgynum enzyme activities of CAT and SOD in untreated material were always higher than in the hardened treatments, while both partial dehydration and ABA treatments tended to reduce both CAT and the induction of SOD activity, although these effects were not significant between the treatments. This suggests that ABA may not be involved in the induction of free radical scavenging enzymes and probably these enzymes are not important in desiccation tolerance of A. androgynum. In lichens, the enzyme activity was measured shortly after collection, after hydration for 48 hat 100% RH, after desiccation for 14 d and 28 d, and during the first 30 min of hydration with liquid water. Enzyme activities tended to rise or stay the same following rehydration in all the species tested. After desiccation for 14 d, enzyme activities decreased, and then decreased further to very low values after 4 weeks desiccation. In all species, including T capensis from an extremely xeric habitat, the activities of all enzymes remained at very low values during the 30 min following rehydration, and were therefore unavailable to remove any reactive oxygen species accumulating in lichen tissues as a result of desiccation. Results suggests that the enzymic antioxidants are more likely to be involved in removing reactive oxygen species produced during the normal metabolic processes of lichens than having a role in desiccation tolerance. The Afromontane understorey moss Atrichum androgynum displayed an oxidative burst of H₂O₂ during rehydration following desiccation. Maximum rates of H₂O₂ production occur during the first 15 min of rehydration. While the production of H₂O₂ increases with increasing desiccation times, the moss produced significant amounts of H₂O₂ during rehydration after desiccation for times that did not inhibit photosynthesis or cause K⁺ leakage. A. androgynum may produce more H₂O₂ during desiccation than rehydration, because desiccation artificially induced using polyethylene glycol strongly stimulates production. Experiments involving inhibitors and exogenously supplied reductants indicate that peroxidases are responsible for the synthesis of H₂O₂. Factors that influence the rate of H₂O₂ production during rehydration include light and the hormone ABA. Patterns of H₂O₂ production are discussed in terms of their possible role as a defence against pathogenic fungi and bacteria.
Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2002.

My PhD work was divided into two phases, according to the aims of my research project: 1) Identify moss species that are good biomonitors of emerging airborne pollutants, especially PAHs, and study the way of interception of these pollutants by moss tissues. 2) Study the effects of heavy metals in selected higher plants evaluating biomass production and tolerance to HM stress, and to estimate their phyto-extracting or phyto-stabilizing capacities for certain heavy metals. As for the biomonitoring of air quality, a Sphagnum palustre clone and three native mosses such as Hypnum cupressiforme, Plagiomnium affine and Amblystegium humile were tested. I focused my attention on the interception and accumulation modes by polycyclic aromatic hydrocarbons (PAHs) by selecting the phenanthrene as target molecule. These pollutants are more difficult to trace than metals because they can be degraded and can be found in the environment in gaseous form or in particles depending on their weight and air temperature; The phenanthrene is self-fluorescent and emits in the red light (620-750 nm), the same wavelength of chlorophyll. Previous work indicated that phenanthrene accumulates in vacuoles, but being the PAHs lipophilic molecules, their accumulation in aqueous compartments such as vacuole seemed unlikely. The results showed that phenanthrene, even opportunely dissolved, aggregates in particles, intercepted by moss surface. The results highlight that among the tested moss species S. palustre was the most efficient in phenanthrene uptake, likely due to its surface properties. In Sphagnum palustre it is accumulated on leaf surface and in hyalocysts, dead empty cells acting in water storage. but Phenanthrene uptake is different depending on moss species. Anyway Physical-chemical characterization of moss surface is the forthcoming step to understand the basis of phenanthrene uptake. As for the point 2 I tested the use of vascular plants with high production of biomass and/or high capacity of bioaccumulation of HM to evaluate their application in phytoremediation or phytostabilization actions; the selected species were Cynara cardunculus e Zea mays. The results showed for both species a good capacity to accumulate Cd and Pb, the first both in shoot and in root and the second mostly in root tissue. Neverthless, C. cardunculus was more sensitive to Pb than Cd while an opposite result was observed in Z. mays, suggesting that both species could be suitable candidate for phytoremediation action (especially phytostabilization), thaking into account their different response depending on the different pollutant. In addition to the effect of toxic metals, the influence of a nutrient (Mn) on mineral uptake was tested as well. In particular, I tested the response of Cistus salvifolius, a species native of a soil very rich in heavy metals, to growing concentration of Manganese. The experiment, carried out in hydroponic culture, showed both an increase of its uptake depending on applied concentrations, and an influence of the Mn on the uptake of some important nutrients such as Mg, K, Fe, Zn; this indicatse that Mn can affect mineral nutrition in C. salvifolius.

Cryptogams are rarely included in conservation planning and management. This study aims to improve the data available for cryptogam conservation by focusing on two groups of cryptogams, mosses and macrofungi, to test the usefulness of vegetation type, vascular plants and environmental variables, including substrate, as surrogates for cryptogams in achieving satisfactory conservation outcomes. Sites from four vegetation types (wet forest, heathy woodland, grassy woodland and alpine heath) in the Hobart region of Tasmania were surveyed over a period of several years for vascular plants, mosses and epigeous macrofungi using permanent plots. Repeated sampling of the macrofungi ensured that a reasonable proportion of the taxa likely to be present were recorded. A total of 284 vascular plants, 71 mosses and 233 macrofungi were recorded. Ordination and analysis of similarity both showed that the four vegetation types were significantly different from each other; this pattern occurred for vascular plants, mosses and macrofungi. Congruence between the three taxonomic groups was tested using Partial Mantel tests; all pairwise associations were highly significant, showing highly predictive r-values. Significant and predictive associations occurred between environmental and substrate variables and biotic groups (vascular plants, mosses and macrofungi, and their various subsets). Canopy cover was the best single predictor of most biotic groups. Particular combinations of significant environmental variables had higher correlations with biotic groups than single variables, for example the combination of altitude, canopy cover and geology had higher r-values than any of these factors individually. Mosses and macrofungi exhibited high substrate fidelity across time and space. Substrate preferences of macrofungi did not vary among vegetation types, but mosses in wet forest occurred on a wider range of substrates than the same species in other vegetation types. Iterative, optimisation, fully random and stratified random methods were compared for their effectiveness in the selection of sites for the conservation of vascular plants, mosses and macrofungi. When 10% of sites were selected for reservation there was little commonality in site selection between the three taxonomic groups. When 30% of sites were selected, at least 48% of all taxa were reserved by all approaches tested. The most useful data sets for selecting sites representative of the three taxonomic groups were vascular plants, named species from all three taxonomic groups and sites selected randomly with equal proportions of each vegetation type. The results suggest that coarse scale conservation of vegetation types with reservation of at least 30% of their area should conserve common mosses and macrofungi. However, at the site scale, uncommon taxa (i.e. taxa only found on a single site) of mosses and macrofungi are not concordant with vascular plants. Associations of moss and macrofungal species with particular substrates and microhabitats may assist with site selections for reservation. For adequate management, further research is required on the occurrence and substrate and habitat specificity of rare taxa.

M.Sc. (Geography)
Gold mine tailings deposits in the Witwatersrand are subjected to intensive wind and water erosion the combination of factors responsible for air and water pollution. Numerous efforts to alleviate this problem through vegetation have succeeded in establishing soil cover, although the surviving species are not representative of original indigenous vegetation and longer-term soil establishment has been poor. Contributing to these difficult conditions for establishing stable soil and plant communities are: low pH values; low surface stability; deficient organic matter and nitrogen; and high levels of heavy metal in the tailings. Although the role of cryptogams on nutrient cycling and positive impacts on growth of plants is well documented, their potential use in the planning of rehabilitation programmes of gold mine tailings has not been explored. In this study, the abundance and diversity of cryptogams and their impact on the chemical properties of Tailings Storage Facilities (TSF) surface material were investigated on three selected tailings dams: Fleurhof (2L3), Rand Leases (2L8), and Durban Roodepoort Deep DRD (2L24). On the third TSF, DRD (2L24), the original vegetation on the northern half has been entirely covered by wind- eroded material from the southern half the current surface represents a fresh un-vegetated surface. Field investigation was conducted to determine the abundance, diversity and coverage of cryptogams and their effect on the surface stability of the selected tailings. Bacteria, cyanobacteria and fungi were isolated and identified to evaluate the diversity and abundance of these organisms in the study area. In addition, electron microscopy observations were performed to understand the formation of the TSF crust. Chemical analyses of pH, electrical conductivity and the nutritional level of cryptogams TSF material were conducted to determine the effects of cryptogams on the chemical properties of the TSF material and predict the suitability of the substrate for the establishment of other microbes and vegetation. Abundant cryptogams, with diversified growth and morphological features, were found within the sampled areas. The cryptogam diversity proved similar to those across the three tailings dams, and was dominated by mosses and lichens. The abundance and growth of these mosses and lichens was dependent on the presence of vegetative cover and the direction of solar radiation. On undisturbed sites, cryptogams covered as much as 30% on DRD, 70% on RL, and 80% on FL. It was observed that the TSF surfaces covered by cryptogams were more stable than the bare ones. Ten genera of cyanobacteria were isolated from samples for the three tailings and identified, based on their morphology and growth characteristics, as: Aphanocapsa sp., Chromonas sp., Chroococcus sp., Cyanothece sp., Microcystis aeruginosa; Microcoleus sp., Nostoc sp., Oscillatoria sp, Scytonema sp. and Stigonema sp. Five fungal (Trichoderma gamsii, Phoma sp., Hypocrea lixii, Lecythophora sp, and Ascomycota) and four bacterial species (Bacillus subtilis, Arthrobacter aurescens, A. histidinolovorans, and A. sulfonivorans), representing the most abundant isolates from each group, iv were identified using DNA sequencing. Under the electron microscope, it was observed that the cryptogams being examined constituted diversified groups of organisms. Mycelia mats and sheathe produced by filamentous cyanobacteria and fungi played a major role in the formation of the crust by binding the TSF particles. The substrate had very low pH, EC, organic matter and nutrients essential for plant growth. However, the presence of cryptogams altered the acidity of the surface material into almost neutral and significantly improved the level of the essential nutrients and organic matter. It was concluded that the diversity of cryptogams in the TSF material was comparable to the diversity reported on other (different) soils. In addition, the cryptogams’ role in ameliorating the chemical properties of the surface material of the TSF is a clear indication that these organisms can play a positive role in stabilising the tailings material surface and promoting the growth of other microbes and higher plant forms.

In arid and semi-arid deserts, soils are commonly covered with biological soil crusts. The study of arid biocrusts and their ecological function has become increasingly common in the literature over the last several decades. Interestingly, no mention is made of biological soil crusts in forested ecosystems, raising the question as to whether they exist in these areas and if they do, why they have yet to be recognized as such? Through the use a parallel logic, this study finds that biocrusts do indeed exist in forests, a novel relationship in forest ecology and seeks to determine if there exist ecophysical explanations for the abundance and distribution throughout the forest landscape. This study examined the effects of climate variables and substrate types on the abundance, distribution and overall cover of forest soil biocrust at fifty-two sites in southern Oregon, U.S.A. Sites were randomly selected within established buffer zones in the Siuslaw, Rogue-Sisikyou, Umpqua, and Fremont-Winema National Forests. The methods of Belnap et al 2001 were tested and then modified for application in forested ecosystems. Data were collected on the relative abundance and distribution of biocrust morphological groups across available substrates, community biocrust morphology, aspect, elevation and soil texture, pH and organic matter content. Site-specific data on average annual precipitation and minimum/maximum temperatures was collected using the PRISM Climate Model. This study found substrate colonization by specific morphological groups mixed across the study; though dominant communities were observed for each substrate present, substrate availability appears to be confounded by a number of variables (climate, stand age and structure and litter layer) not controlled for in this study. Biocrust community morphologies varied across sites, primarily influenced by the surface texture of the substrate and morphology of the individual. Relatively smooth surfaces (rock, bare soil) often resulted in smooth biocrust morphologies, whereas rough surfaces (dead wood, bare soil) tended to result in a rolling morphology. Litter layer directly influenced the relative proportion of substrates colonized, notably affecting dead wood and mineral soil biocrusts. Total biocrust cover increased as precipitation increased as did biocrust preference for dead wood substrates while mineral soil remained unchanged and rock surfaces were negatively represented. Aspect generally followed the anticipated distribution of total biocrust cover with the highest cover on N and NW aspects and lowest on the W aspect. Increases in elevation were negatively related to overall biocrust cover. Soil texture was not found to be directly related to overall biocrust cover, attributed in part to the highly adaptive nature of the biocrust community. Soil organic matter (SOM) influenced total biocrust cover with positive correlations between total cover and increasing SOM content. Soil pH increased as expected across the precipitation range (17 to 159 in/yr) of the transect. Total biocrust cover was found to trend with soil pH, but is believed to be attributed to the parallel relationship between precipitation and pH, rather than pH alone given the relative moderate pH range (4.39 to 6.54) of the study. The distribution and abundance of forest soil biocrusts is strongly influenced by precipitation. The confounding influence of precipitation to litter layer depth and organic matter content (through gradients of vegetative productivity) and soil pH further are concluded to influence substrate preference by morphological groups. Across the variables examined, similarities between the two communities (arid and forest) in response to climate and soil chemistry show parallel relations, justifying the formal establishment of biological soil crust community in forested regions. The differences between communities related to the presence of trees validate the establishment of forest soil biocrusts as distinct community in both form and ecological function with the forests.
Graduation date: 2013

碩士
銘傳大學
資訊工程學系碩士班
106
The shares in a set of qualified visual cryptograms of random grids (VCRG-GAS) do not need an extra pixel expansion and look like random pictures. However, when one participates the sharing of several secrets, he/she is confronted with the inconvenience for managing the shares at hand (such as not easy to identify which share is the right one). We propose feasible TVCRG and VCRG-GAS with meaningful shares in this research: Given secret image P, threshold k and n meaningful pictures, the n encoded visual cryptograms of random grids look like the n meaningful pictures and the superimposed result of any k or more shares for TVCRG (or each qualified set for VCRG-GAS) reveals P without the interference of the meaningful shares, while that of any less than k shares (or each forbidden qualified set) gives nothing to P. Experimental results (including the contrast analyses on the meaningful shares and on the revealed secret) demonstrate the effectiveness of our scheme. are also examined.

碩士
靜宜大學
資訊傳播工程學系碩士班
98
Abstract Visual cryptography is a kind of information hiding technology, which has two features of the decoding process and no computer calculations. Visual cryptography can align the shares and then use human visual to realize the secret image. Visual cryptography usually uses the strategy of pixel expansion and strategy of color contrasting, but the former will make the shares images not easy to carry. The random grids technique randomly assign black and white pixels of the shares by some probability distribution, which also can output shares without pixel expansion. The random grids will let shares image be fixed probability, which will lead stacked image too dark to recognize. This paper proposes a method, which can change the probability distribution of black and white pixels. Our method can increase the number of shares and improve the quality of stacked images, which also maintain the security of pixels in the secret image on the random. Our experimental results show our method is practical.

This project is a pilot study to assess the viability of transplantation as a technique to establish reindeer lichens on reclaimed areas of oil sands surface mines in the Athabasca region of Alberta. There were two components to this study: a) a lichen transplant trial, where I investigated which commonly available substrates found in reclaimed forest sites would promote the best lichen fragment survival and vigour for a lichen ‘seeding’ program; and b) a diversity assessment of the reclaimed site to compare the existing cryptogam community with the expected community for the target ecosite based on published descriptions from the surrounding native forests and documented chronosequences for terrestrial lichen communities. In July 2009, Cladonia mitis was transplanted into 54 plots on three sites that were planted with jack pine or spruce 12 or 24 years ago, respectively, on the Suncor Millenium/Steepbank Mine (Suncor Mine). This trial was designed to investigate possible short-term indicators of successful lichen establishment and the effect of substrate (moss, litter, or soil) on the establishment of transplanted lichen thallus fragments. The indicators of lichen establishment evaluated were vigour, movement from plots, photographic areal cover, and microscopic growth (hyphal growth, annual growth and lateral branching). After two growing seasons, the effect of substrate on lichen transplant survival varied by site; there was no significant difference in lichen fragment retention in plots by substrate on the 24-year old sites, but median fragment retention was significantly higher on moss and litter substrates than soil on the 12-year old site. There was also no significant difference in fragment vigour between substrates on each site, except on the south-facing 24-year-old forest site where average vigour was significantly higher on moss plots than on soil plots. Photographic areal measurement is not recommended as a short-term lichen establishment monitoring tool for transplanted fragments based on the difficulties encountered using the method for this trial. Forty-one percent of the fragments collected for microscopic assessment after the first growing season had grown hyphae, 23 percent of the fragments collected during September 2009 and September 2010 had formed apothecia, and 31 percent of the fragments collected in September 2010 had grown lateral branches. The results of the biodiversity assessment were compared with the successional communities previously described for spruce- and pine-lichen boreal forests. There were no lichens found on the 12-year-old site, though the cup lichens were common to abundant on the 24-year-old sites, which is consistent with the cryptogammic community expected for a regenerating natural site of that age. Cladonia mitis was also present but rare to uncommon on the 24-year-old site, while Cladonia stellaris, Cladonia rangiferina and Cladonia stygia that, together with C. mitis, are indicative of the al and c1 ecosites of the Central Mixedwood Boreal forest, were not present.
Graduate

Cryptogam communities on coarse woody debris persist in forests regenerating after the first clearfell, burn and sow harvesting rotation due to harvest residue. The habitat disturbance dynamics in a regenerating forest is different from the natural wildfire disturbance, as is the dynamics of coarse woody debris, which, while different, also provides an opportunity for new bryophyte community development. How bryophyte communities develop in response to this new system dynamic is largely unexplored. Community development may depend on time since disturbance and/or the degree of decomposition of the coarse woody debris. For individual species and communities as a whole, it is not known which of these two effects dominates or what environmental attributes affect the resulting communities. This research attempts to tease apart these issues by examining the time dependent response of cryptogamic communities growing on coarse woody debris to first rotation clearfell, burn and sow harvesting and the relative significance of forest age and log decay progression on community succession. Subsequent to clearfelling, cryptogamic communities on coarse woody debris were compared from wet eucalypt forests of increasing age. There were significant differences in species richness and community composition between forest age and between log decay stage. Older forests were the most species rich. More individual species had significant associations with logs of intermediate decay classes than with logs of an earlier decay class. The ecology of individual species varied considerably for forest age and log decay class associations and there were distinct early, middle and late successional species identified. Forest climate measures of temperature and vapour pressure deficit were used as an indication of the variation in large scale habitat conditions over time between forests of each age and to examine the influence of habitat conditions associated with forest age on of coarse woody debris. There were significant changes over time for temperature and vapour pressure deficit where mesoclimatic conditions became less variable as forest age increased. Log moisture was a direct measure of the fine scale habitat conditions influencing cryptogam communities of coarse woody debris, especially in relation to log decay stage. Log moisture had a significant influence on bryophyte community composition over time and was important for determining the succession of cryptogamic communities when combined with mesoclimatic conditions. The effect of forest age and log decay stage on cryptogam communities of coarse woody debris suggests that both of these time dependent processes play an important role in community succession, and that the distinction between the two habitat variables may vary depending on time since clearfell, burn and sow disturbance. Fine scale community analysis revealed that at any forest age and at any decay stage there were significantly associated species. While this study has shed some light on how succession plays out in the first decades of the first clearfell, burn and sow rotation, it also suggests that communities follow a predominantly similar successional pathway as would occur in a forest regenerating after natural wildfire disturbance; however, it is likely that successive harvesting events based on 100 year rotations will result in the loss of some cryptogam species. Managing forests after clearfell, burn and sow for the development of mature stands and for actively facilitating the persistence of a range of decay stages and coarse woody debris habitat structures at the site and landscape levels may be appropriate, and the findings of this study are discussed in this context.