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1
Scobie, Andrew Rutherford. "Understanding the causes of reproductive failure in two rare Scottish plants, Linnaea borealis L. and Spiranthes romanzoffiana Cham. and the implications for future conservation management". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until Dec. 21, 2011, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59437.
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2
Smetanyuk, О. І. "Rare medicinal plants of Chernivtsi region". Thesis, БДМУ, 2017. http://dspace.bsmu.edu.ua:8080/xmlui/handle/123456789/17334.
Testo completo
3
Swarts, Nigel. "Integrated conservation of the rare and endangered terrestrial orchid Caladenia huegelii H.G. Reichb /". Connect to this title, 2007. http://theses.library.uwa.edu.au/adt-WU2008.0044.
Testo completo
4
Hughes, Lee E. "Two Rare Plants of the Arizona Strip". University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/554247.
Testo completo
5
Dalrymple, Sarah. "Rarity and conservation of Melampyrum sylvaticum". Thesis, University of Aberdeen, 2006. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=128181.
Testo completoAbstract (sommario):
Melampyrum sylvaticum (small cow-wheat) is a hemiparasitic annual of boreal-montane regions of Europe. The Species Action Plan recommended that in addition to protecting extant populations, by 2010 there should be an additional five populations that have been created with the aim of enhancing greater genetic diversity of the species. Consequently this project was set up in order to provide the ecological knowledge required to meet such targets. There are various management options available to conservationists looking to prevent Melampyrum sylvaticum’s extinction from the UK but from the results of this project it is clear that some methods have drawbacks that should preclude their use. Population augmentation with seeds from other populations is not advised due to the risk of genetic ‘swamping’ or outbreeding depression. Seed amplification would avoid these problems but may introduce different complications by artificially promoting certain genotypes within a population. Population expansion by mimicking ant dispersal is recommended as a way of minimizing density dependent mortality in larger populations but is not suitable in smaller populations. Seed translocation to unoccupied sites is therefore, the best option but the exact details of seed-sourcing and sowing should be guided by the results of the Species Recovery Project in order to avoid predicted limitations. The long-term outlook for M. sylvaticum will depend entirely on whether populations can be created that operate as part of a functioning ecosystem (including pollinating and seed-dispersing insects) with enough demographic and genetic stability to survive predicted climate change.
6
Horsman, Frank. "Botanising in Linnaean Britain : a study of Upper Teesdale in northern England". Thesis, Durham University, 1998. http://etheses.dur.ac.uk/983/.
Testo completoAbstract (sommario):
The Swede, Carl Linnaeus (1707-1778), introduced an artificial " Sexual System " of plant classification in 1735, and a binomial system of nomenclature in 1753. They made plant identification much easier. The Linnaean period in Britain lasted from 1760 until [1810-]1830. It is demonstrated that it was during this period that it was first recognised that an unusually high number of rare plants grow in Upper Teesdale. Most of the rare plants of the then very remote Upper Teesdale were discovered shortly after 1783 by William Oliver (1760-1816), alone. He was a surgeon and part of a medical dynasty. How he became a botanist, with his medical background, is examined in detail. He trained at Edinburgh but did not do botany. However, he knew John Hope, the Professor of Botany. Hope was one of only two people teaching the Linnaean system in Britain at this time. The appearance of Linnaean floras of Britain in English from the 1770's onwards made field botany accessiblet o anyone. Previously complex natural systems of plant classification and the use of Latin had restricted access. How Oliver's discoveries were made known is examined in detail. It involved Rev. John Harriman (1760-183 1) who was influenced by the Linnean Society of London, formed in 1788, and the Linnaean English Botany which began in 1790. H-e wanted to become a Fellow of the Linnean Society. James Edward Smith was President of the Linnean Society and an author, with James Sowerby, ofEnglish Botany. IV alic, ,j Lrf Edward Robson (1763-1813), a Quaker botanist and already an Associate of the Linnean Society, and his compilation: Plantae rariores agro Dunelmensi indigenae of 1798, and John Binks (1766-1817), an artisan botanist. Medicine made botanists of both Harriman and Binks, as well as Oliver. Linnaeus influenced the teaching of materia medica (the plant simples).
7
Binney, Elizabeth P. "Comparative analysis of community and population levels of organization in the rare grass, Achnatherum hendersonii". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ27107.pdf.
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8
Nock, Erin Elizabeth. "A simple GIS approach to predicting rare plant habitat north central Rocky Mountains, United States Forest Service, Region One /". CONNECT TO THIS TITLE ONLINE, 2008. http://etd.lib.umt.edu/theses/available/etd-06102008-173011/.
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9
Wheeler, Belinda Ruth. "Aspects of the ecology and conservation of the rare plant species Phyteuma spicatum L (Campanulaceae) in the British Isles". Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363382.
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10
Swarts, Nigel. "Integrated conservation of the rare and endangered terrestrial orchid Caladenia huegelii H.G. Reichb". University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0044.
Testo completoAbstract (sommario):
The Orchidaceae is characterized by a remarkably diverse range of life forms and some of the most highly specialized interactions with soil fungi and insect pollinators found in the flowering plants. Many species are rare or threatened with extinction either directly through loss of habitat or over-collection or, indirectly through debilitation or loss of mycorrhizal association or pollinator capacity. Australian temperate terrestrial orchids represent one of the most threatened groups in the Australian flora with many taxa clinging to existence in urban and rural bushland remnants, road verges and unprotected bushland. The aim of this study is to research and develop integrated conservation based on critical aspects of terrestrial orchid biology and ecology, towards the recovery of the rare and endangered Western Australian terrestrial orchid Caladenia huegelii. This study identified key aspects involved in an integrated conservation approach and research focused on conservation genetics, mycorrhizal interactions and in situ and ex situ conservation strategies for this species. Using polymorphic microsatellite molecular markers, high levels of genetic diversity were found within remnant populations of C. huegelii, while weak differentiation was observed among populations over the species geographic range. These results indicate historic genetic exchange between C. huegelii populations, a possible consequence of the sexually deceptive pollination strategy and the capacity for widespread seed dispersal. Symbiotic germination studies revealed compatibility barriers to C. huegelii germination with the orchid possessing a highly specific orchid-mycorrhizal association relative to common sympatric congeners. These results were reflected in a phylogenetic analysis of DNA sequences, revealing C. huegelii associates with only one endophyte species within the fungal family Sebacinaceae across its geographic range. Large scale in situ seed baiting demonstrated that endophytes compatible with C. huegelii were limited in distribution relative to common and widespread orchid species, a feature for C. huegelii that may be a major contributing factor in limiting the distributional range of the species. Detailed, within site seed baiting methods identified hotspots for mycorrhizal fungus compatible with C. huegelii that were unoccupied by the orchid. These mycorrhizal hotspots where used to investigate the effect of endophyte presence on survival of transplanted mature plants and seedling outplants. The in situ survival of glasshouse propagated seedlings was further optimized by incubating seedlings in growth containers before transfer to soil and outplanting seedlings in their second growing season. The findings of this study will substantially advance the recovery of C. huegelii and provide benchmark knowledge for similar projects with other rare and threatened terrestrial orchid species.
11
Dalton, Naomi Jane. "Pollinators, plants and people : a transdisciplinary study of rare species conservation". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.688353.
Testo completoAbstract (sommario):
Translocation is widely used to counter the fragmentation and decline of populations of species at risk, in order to enhance their survival prospects. Additionally, translocation is used in ecological restoration to introduce taxa conferring strong positive influence, with the potential to recreate communities and reinstate functional roles. Conservation of species by translocation is considered high risk and high cost; therefore ecologists need to understand how success can be maximised. In this thesis, I test the community level impacts of a rare plant and evaluate the effectiveness of single-species conservation for bottom-up restoration. To do this I study the effect a rare plant species, Sium latifolium, has on pollinator communities and find a strong local effect, but detect no population level change. I conclude that the addition of a single plant species is ineffective at providing population change. For evaluation of conservation strategies for pollinators, population level impact must be tested for, rather than assuming that they mirror the local effect. I then explore options for improving the success of species translocation, adopting methodologies from population genetics and social sciences. I test whether low genetic diversity limits the success of S. latifolium translocations, predicting that introduction survival correlates with diversity of the donor natural population. I reject this hypothesis and conclude instead that, for S. latifolium, ecological conditions determine initial success of introductions. Much experience for this resides with practitioners, therefore I use social network analysis to quantify communication between people conserving S. latifolium. I test whether a small scale network intervention (organising a meeting) can create new ties and improve knowledgeexchange through the network.
12
Burke, Jennifer L., e University of Lethbridge Faculty of Arts and Science. "The evolutionary origins of Erigeron trifidus, a rare plant in Alberta". Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2005, 2005. http://hdl.handle.net/10133/244.
Testo completoAbstract (sommario):
The present study analyzed the evolutionary history of Erigeron trifidus Hook. by addressing two main questions: 1) Is the current hypothesis of the origin of the species by hybridization between E.compositus and E.lanatus supported by molecular data? and 2)Is the species monophyletic? An analysis of uni-and-biparentally inherited molecular markers from three species throughout the range of E.trifidus yielded data that supports the hybridization hypothesis. First, a restriction site analysis of cpDNA revealed 4 haplotypes. In most cases, cpDNA haplotypes were the same as in E.lanatus, suggesting E.lanatus as the maternal parent. Sequencing and cloning the nuclear ETS region revealed the presence of multiple repeat types in most individuals sampled. This further supports the hybrid origin hypothesis in that E.trifidus contained only repeat types present in one or the other of the putative parents. In addition, E.trifidus displayed the highest percentage of intrainidividual repeat type polymorphism, a common trait of hybrid species. Erigeron trifidus populations collected in the northern region appear to be monophyletic as they all exhibited a particular pattern of repeat type variation, a pattern absent in Ram Mountain and Waterton Lakes National Park populations. As E.lanatus has never been recorded from Ram Mountain, it is likely that the populations identified as E.trifidus are instead a different agamospermous variant of E.compositus. In Waterton Lakes National Park, populations of E.trifidus are thought to be the product of local hybridization but the identity of the putative parents remains uncertain. Therefore, E.trifidus is concluded to be polyphyletic.viii, 66 leaves : ill. (some col.) ; 28 cm.
13
Griffiths, Megan Elizabeth. "Salt spray effects on rare New England coastal sandplain heathland plant communities /". Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.
Cerca il testo completoAbstract (sommario):
Thesis (Ph.D.)--Tufts University, 2003.Adviser: Colin M. Orians. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 181-200). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
14
Last, Mariana P. "Intraspecific Phylogeography of Cycladenia humilis (Apocynaceae)". BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2287.
Testo completoAbstract (sommario):
Cycladenia humilis (Apocynaceae) is a rare perennial herb native to western North America and has a fragmented distribution in California, Utah, and Arizona. Populations in Utah and Arizona are federally listed as threatened, while there is no conservation status applied to California populations. Using genetic (three chloroplast and two nuclear DNA loci) and morphological characters, intraspecific variation between populations of C. humilis and current taxonomic conventions were assessed. Nested Clade Phylogeographic Analysis and Bayesian phylogenies were used to assess patterns within C. humilis and supported three main population groupings: a northern California, southern California, and Colorado Plateau group. The northern California populations represent a distinct group and include populations from the Santa Lucia Mountains contrary to current classifications. The southern California group consistently includes populations in the San Gabriel and Inyo Mountains and was unique from any other region. The Colorado Plateau represents a group distinct from all other groups. The resilience of C. humilis on the Colorado Plateau to human threats remains unknown, but based on its frequency being comparable to California and our findings that considerable genetic variation exists within the species and within populations on the Colorado Plateau, we recommend that the threatened status of C. humilis be lifted.
15
Kaye, Thomas N. "Population viability analysis of endangered plant species an evaluation of stochastic methods and an application to a rare prairie plant /". Connect to this title online, 2001. http://fresc.usgs.gov/products/thesis/kaye/thesis.html.
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Bonner, Jerri LeAnne. "The influence of beaver impoundments on vegetative composition, and modeling habitat suitability as a tool for wildlife management and conservation". Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4396.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2005.Title from document title page. Document formatted into pages; contains ix, 119 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references.
17
Ofisi, Mbulelo. "In vitro propagation studies of rare Argyroderma species strictly endemic to the Knersvlakte region of South Africa". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2714.
Testo completoAbstract (sommario):
Thesis (MTech (Horticulture)--Cape Peninsula University of Technology, 2017.A study was conducted to investigate the effects of various media composition and wounding treating on the in vitro propagation of Argyroderma subalbum and A. testiculare explants derived from mature plants, antioxidants and plant growth regulators (PGR) concentrations. One experiment consisted of 3 medium types including Murashige and Skoog (MS) medium strength, vitamin supplement. Fifteen replicates were used for each treatment. The shoots were then sub-cultured to ten replicate regenerated medium consisting of varying levels and combination of indole-3-acetic acid (IAA) and 10 μM 6-Benzyladenine (BA) supplements. In another experiment consisted of varying levels of auxins with MS medium strength, activated charcoal (AC) and vitamin supplements ten replicates were used for each treatment. Results indicated the positive role of cytokinins types’ 6-Benzyladenine (BA), 2-isopentyladenine (2iP) and Kinetin in inducing callus formation from wounded explants. The highest rate of friable callus formation of wounded explants was observed in media containing vitamin supplementation with BA at 10 μM. Callus formation significantly increased with the addition of vitamins at 10 μM on BA, 2iP and kinetin. With regards to the effects of various media composition and wounding explants on in vitro growth and regeneration of A. subalbum and A. testiculare, significant results were achieved with BA, 2iP and kinetin concentrations on explants discoloration and callus formation. The antioxidant treatment, AC did not reduce explants discoloration, but the induction of the callus was developed furthermore, results showed that IAA with BA concentrations without addition of AC there was significantly difference on both species but A. subalbum dominated with browning intensity (Chapter 3). Only sub-culturing of the explants succeeded in preventing explants discoloration and subsequently increased the number of shoots. The interaction between Indole-3-acetic acid (IAA) concentrations combined with BA resulted in the most effective technique in reducing explants discoloration at the media contact point. This study provides an insight into the contributing factor and methods of overcoming the major problem of phenolic oxidation and promoting the in vitro growth and regeneration of A. subalbum and A. testiculare.
18
McCue, Kimberlie A. "The ecological genetics of rarity : a study of genetic structure, inbreeding and seed bank dynamics in a rare annual plant /". free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841324.
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McKenna, David J. "Demographic and ecological indicators of rarity in a suite of obligate-seeding Persoonia (Proteaceae) shrubs". Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080131.142010/index.html.
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Gruner, Ingrid Gerda. "Comparative Ecology and Conservation of Rare Native Broom, Carmichaelia (Fabaceae), South Island, New Zealand". Thesis, University of Canterbury. School of Forestry, 2003. http://hdl.handle.net/10092/4152.
Testo completoAbstract (sommario):
Using a comparative approach, the presented study explores the ecology of ten species of native New Zealand broom, Carmichaelia, and their vulnerability to competition and herbivory, with the aim of gaining a better understanding of the significance of introduced species as a threat to rare indigenous plants in New Zealand. In particular, the study focuses on the relationship between characteristics of the Carmichaelia species and their vulnerability, as well as on other factors influencing the significance of introduced species as a threat.
To gain a better understanding of the ecology of the Carmichaelia species, their current habitats and associated plant communities were investigated using quantitative-descriptive methods in the field. The effect of competition with introduced plants was studied in two glasshouse experiments, differentiating above ground competition for light from below ground competition for nutrients and water. The experiments focussed on the early life-stage
of seedling establishment of the Carmichaelia species. The impact of herbivory by introduced mammals was studied in four field-based exclosure trials, focussing on the effects on survival and reproductive activity of adult Carmichaelia plants.
The results showed that the effects of competition and herbivory vary between the different species. Furthermore, they provided a set of species characteristics that can be used as indicators to predict the vulnerability of Carmichaelia to the impact of introduced species. These indicators provide a useful tool for threatened species management, as they allow the identification of the most vulnerable species as well as the most significant threat to each species. Furthermore, the indicators can be used to group species, combining those with similar vulnerability profiles, and therefore, likely similar management needs.
However, the example of the Carmichaelia species also illustrated that the use of indicators for the vulnerability of threatened species is limited and needs to be combined with case-by-case studies to verify the actual significance of threats for each population of concern. The
vulnerability profiles derived from species’ characteristics can be used to guide such site specific
studies, ensuring they focus on the most relevant threat factors. This combination of the understanding of general patterns in the vulnerability of species with targeted species and site-specific studies will lead to increased efficiency in the conservation management of threatened plant species.
21
Blanchard, Jennifer L. "Environmental analysis of the habitat (biotic and abiotic factors) associated with Broadleaf Barbara's Buttons (Marshallia trinervia)". ScholarWorks@UNO, 2009. http://scholarworks.uno.edu/td/1010.
Testo completoAbstract (sommario):
In June 2009 I conducted a study of the habitat associated with Broadleaf Barbara's Buttons (Marshallia trinervia) along Bird's Creek in Vernon Parish, LA. Twenty two plots were sampled for all vascular plants. Of these, 17 samples were from the area where M. trinervia was present and 5 samples were from the area where M. trinervia was absent. From each sampling plot a soil sample was collected and analyzed. There were significant differences in the species richness of all plant groups (p=0.0075), herbaceous plants (p=0.056), and woody vines (p=0.083) between the two locations. The soil texture was also significantly different in the percentage of sand (p=0.021), silt (p=0.029), and clay (p=0.089) between the study locations. The study found that the samples associated with M. trinervia were higher in species richness for all plant groups and the soils from these locations had a higher mean percentage of silt and clay particles.
22
Williams, Aleida Helen. "An ecophysiological comparison of rare ironstone endemics and their common congeners". University of Western Australia. School of Plant Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0241.
Testo completoAbstract (sommario):
[Truncated abstract] In south-western Australia a rare plant community occurs on shallow soils overlaying massive ironstone rock. These 'ironstone communities' are open shrublands, which are subject to extremes in drought and solar radiation and support many rare and endemic species. The restricted distribution of many of these species may be related to their high degree of specialisation to this harsh habitat and their inability to respond plastically to different environmental conditions. Indeed, earlier work has shown that ironstone Hakea species (Proteaceae) have a specialist root-system morphology investing mainly in deep roots, thereby increasing their chance of accessing cracks in the rock surface and obtaining water before the onset of summer drought. In this thesis I further examine aspects of specialisation and its possible consequences for species rarity using two ironstone Hakea species and comparing them with two of their widely distributed congeners. In the first experiment (Chapter 2) I explore inherent drought tolerance, independent of root-system morphology, as a further specialisation to the ironstone environment. All species were grown in sand in pots in a glasshouse for 7 months and then droughted for 5 weeks. There was no evidence that the ironstone species had a greater inherent drought tolerance than their common congeners. During drought all species maintained leaf water content of mature leaves by reducing stomatal conductance and osmotically adjusting, though ironstone species tended to OA (osmotic adjustment) more than common species. ... This suboptimal investment of resources may result in a lower competitive ability in shadier environments, and thus could partially explain their restricted distribution. In Chapter 4, I investigated the plasticity of root traits in response to levels of phosphorus supply. South-western Australian soils are phosphorus impoverished and phosphorus is well known to elicit plastic responses in root allocation and architecture. Ironstone species showed less plasticity in total root length, producing similar root length across P treatments, while common species showed an increase in root length with increasing [P]. Other root characteristics were similarly plastic in response to P treatment between species. However, when supplied with increasing [P], ironstone species invested an increasing proportion of roots in the bottom of pots while common species invested more in the top. This differential response in root allocation in response to P may reflect a fundamental trade-off between nutrient and water acquisition, with the ironstone species mainly foraging for water and investing in deeper roots, while the common species invest more in superficial roots to obtain nutrients. In conclusion, the rarity and restricted distribution of the ironstone Hakea species may be related to their specialist root-system morphology as well as a lowered phenotypic plasticity of functional traits. A reduction in plasticity may reduce their competitive ability outside their ironstone habitats, and thus contribute to the restricted distribution of these species. This may also be the case for other rock-outcrop endemics and more generally, for other rare plant species restricted to particular habitats where a lowered phenotypic plasticity in traits relevant to their particular habitat may contribute to their restricted distribution.
23
MARIA, SHEILA P. "Estudo das caracteristicas de distribuicao de elementos terras raras em Solanum Lycocarpum em diferentes ambientes tropicais do Brasil por ativacao neutronica". reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10843.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:97/14381-1
24
CARVALHO, MARCOS R. de. "Metodologia para determinacao da eficiencia de um monitor de gases emissores de particulas beta". reponame:Repositório Institucional do IPEN, 1995. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10662.
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Dissertacao(Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Lang, Marion [Verfasser], Harald [Akademischer Betreuer] Albrecht, Hanno [Gutachter] Schäfer, Christoph [Gutachter] Leuschner e Harald [Gutachter] Albrecht. "Reintroduction of rare arable plants on agricultural fields / Marion Lang ; Gutachter: Hanno Schäfer, Christoph Leuschner, Harald Albrecht ; Betreuer: Harald Albrecht". München : Universitätsbibliothek der TU München, 2021. http://d-nb.info/1237815894/34.
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Foster, Kathleen. "Design of an inlet line monitor system for the state of Illinois gaseous effluent monitoring system". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17323.
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Gray, Jennifer L. "HABITAT CHARACTERIZATION AND INVENTORY OF COLLINSONIA VERTICILLATA IN SHAWNEE STATE FOREST AND STATE PARK, SCIOTO COUNTY, OHIO". Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1149184142.
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ZINI, JOSIANE. "Usos das cromatografias de extracao e de troca ionica na separacao de torio e terras raras de residuos industriais gerados na unidade de purificacao de torio do IPEN. Aplicacao das terras raras como catalisadores na geracao de hidrogenio". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9532.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
29
Weber, Robert Joseph. "An experimental study of fractionation of the rare earth elements in poplar plants (Populus eugenei) grown in a calcium-bearing smectite soil". Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/935.
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Staniulytė, Erika. "Antropogeninio poveikio įtaka Vidzgirio botaninio draustinio retiems augalams". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2007~D_20070816_153338-83545.
Testo completoAbstract (sommario):
Magistro baigiamąjį darbą sudaro 57 puslapiai. Jame yra 8 lentelės, 31 paveikslėliai, 44 literatūros šaltiniai ir 13 priedų.
Magistro darbe tiriama antropogeninio poveikio įtaka Vidzgirio botaninio draustinio retiems augalams.
Darbo objektas- reti augalai augantys Vidzgirio botaninio draustinio teritorijoje.
Darbo tikslas- įvertinti retų augalų dinamiką per pastaruosius metus ir ieškoti priemonių jų išlikimui.
Darbo metodai- retų augalų gausumui nustatyti naudojomės Botanikos instituto parengta monitoringo metodika (Parengta Zigmanto Gudžinsko 2001 m. Botanikos institutas, Floros ir geobotanikos laboratorija). Aprašant augavietę kiekvienos rūšies augalų gausumas ir padengimas vertinami balais pagal Braun- Blanquet skalę .
Atlikus tyrimus ir įvertinus retų augalų paplitimą nustatyta, kad 7 iš 11 rastų retų augalų auga antropogeninio poveikio zonoje Jų augavietės yra šalia upelio, piliakalnio ir mokomojo tako. Šios vietos yra gausiai lankomos. Reti augalai augantys Vidzgirio botaniniame draustinyje nukenčia nuo intensyvios rekreacijos, kirtimų, šiukšlių.
Tyrimų metu nustatyta, kad sumažėjo tamsialapio skiautalūpio individų skaičius. Pagausėjo plačialapės klumpaitės individų skaičius. Rastos naujos retų augalų augavietės.
Norint užtikrinti saugomų augalų augaviečių stabilumą, ypač vertinguose miško sklypuose reikia taikyti tokį patį ūkininkavimo režimą, kaip I grupės miškuose, visoje draustinio teritorijoje vengti bet kokių introdukuotų augalų rūšių sodinimo, sureguliuoti... [toliau žr. visą tekstą]Final master degree work of University, 57 pages, 31 figures, 8 tables, 36 references, 44 appendix. Master degree work cover the studies of antropogenic effect to the rare plants, which are growing in the botanical conservation area of Vidzgiris. The object of research- rare plants growing in conservation area of Vidzgiris. The aim of research- to evaluate dynamic over the recently years of rare plants and to seek measures for their survival. These methods were used while writing the work: for the identifying superfluity of rare plants the monitoring methods were applied prepared by the Botanical Institute (prepared by Zigmantas Gudžinskas 2001, Botanical Institute, in Flora and Geobotany laboratory). By using descriptive method it was evaluated the superfluity and coating of every sort of plant for populations association using Braun- Blanquet rates scale. After research and evaluating spread of rare plants instituted that 7 of 11 rare plants are growing in the zone of antropogenic effect. They growing places are near the stream, mound and educational path. Rare plants in the botanical conservation area of Vidzgiris are influencing by intensive recreation, deforestation, rubbish. At the time of research estimated that number of Epipactis atrorubens has decreased. Number of Cypripedium calceolus has increase. Were found new places were rare plants can grow. That to secure protected rare plants growing places is need to fit farming mode like in the I group forest... [to full text]
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Kartavičiūtė, Gintarė. "Vištytgirio botaninio- zoologinio draustinio Raudonosios knygos būklės tyrimai". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140616_104844-90142.
Testo completoAbstract (sommario):
Įvertinti Raudonosios knygos augalų paplitimą, būklę, bei kaitą ir pasiūlyti priemones jų būklei ir paplitimui pagerinti.To assess the distribution of plants of red list, their condition and changes in Vištytgiris botanical-zoological rezerve; and identify measures to improve their condition and spread.
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Clark, Sarah Lynn. "Reproductive biology and impacts of energy development on Physaria congesta and Physaria obcordata (Brassicaceae), two rare and threatened plants in the Piceance Basin, Colorado". DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1502.
Testo completoAbstract (sommario):
The Piceance Basin in western Colorado has undergone a drastic increase in oil and gas development over the last two decades. This increase has escalated concerns about the effects of development on the Basin’s flora and fauna, especially the rare plant community. Potential impacts from oil and gas development on rare plants may be found through decrease in plant habitat or by a decrease in plant reproductive success through changes to important pollinator communities. Here, we observed the pollinator community on two rare mustard plants, Physaria congesta and Physaria obcordata (Brassicaceae), both listed as threatened by the US Fish and Wildlife Service (Federal Register 55 FR 4152). We studied a series of questions concerning the pollinator community important to each Physaria species. The experiments were conducted in the spring of 2010 and 2011 during the blooming season of each rare Physaria. We investigated the effect of oil and gas development on the pollinator community by evaluating abundance, diversity, behavior, and foraging rates along a distance gradient from roadsides. This study also examines plant fecundity to determine the extent of pollinator efficiency across the same distance gradient from roadsides. Additionally, we examine nesting success of pollinators within plant populations, as well as around natural gas wellpads. Further, we conduct a breeding system and cross pollination study on P. congesta to determine the importance of pollination services for reproduction. To determine overall pollinator community changes around other development types we sampled pollinators around wellpads. Our data supports the null hypothesis, suggesting that at this time oil and gas development may have little to no impact on the pollinator community abundance. The analysis conducted may not have been able to detect changes in the community, due to a small sample size of pollinators collected.
Bee pollinators may forage on a few or many floral resources. Here, we account for the ancillary foraging resources of P. congesta and P. obcordata pollinators by identifying pollen removed from bees collected on rare Physaria. This specific community of plants may require conservation in addition to the rare plants, to assist in maintaining the pollinator community.
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Moreira, Carolina Mathias. "Avaliação de métodos fitossociológicos através de simulações de amostragens numa parcela permanente de cerradão, na Estação Ecológica de Assis, SP". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-05062007-134450/.
Testo completoAbstract (sommario):
Existem vários métodos empregados em estudos fitossociológicos e muitos trabalhos já se propuseram a avaliar o desempenho desses métodos. O primeiro e mais utilizado é o método de parcelas, que sempre é referido nos trabalhos como o melhor e por isso definido como base para comparação com os demais. Por esse motivo, nunca foi avaliado isoladamente. Com o presente trabalho tem-se a oportunidade de avaliar o próprio método de parcelas, comparando seus resultados com os valores paramétricos, uma vez que foi feito um censo da área amostrada e a população estatística é conhecida sem erro amostral. Os dados são de uma parcela permanente instalada em uma área de cerradão (Estação Ecológica de Assis, SP). A parcela possui 10,24 ha e todos seus indivíduos com CAP ≥ 15 cm foram marcados, georreferenciados, medidos e identificados. Foi feita uma tabela de fitossociologia para a parcela que, por se tratar de um censo, representa os valores paramétricos. Foram geradas simulações de levantamentos fitossociológicos por amostragens sistemáticas para quatro tamanhos de parcela quadrada, sendo 10 x 10 m, 20 x 20 m, 50 x 50 m e 100 x 100 m, todas com área total amostrada de 1 ha. Para a parcela de 10 x 10 m foram simuladas mais três intensidades amostrais: 75, 50 e 25 parcelas. Para cada situação de amostragem foram simuladas 1.000 amostras e para cada uma dessas amostras foi elaborada uma tabela de fitossociologia. Foi avaliado o viés das etimativas de densidade e dominância, e a alteração da posição das espécies na tabela de fitossociologia. Foi avaliada também a influência da distribuição espacial das espécies nas etimativas. Por fim, foram feitas algumas análises de atributos de comunidade que são viáveis à partir de levantamentos fitossociológicos, como densidade, área basal, curva de acumulação de espécies, número de espécies amostradas e proporção de espécies e indivíduos por classe de densidade. O método de parcelas de 10 x 10 m foi o que apresentou menor viés para as estimativas, e também menor variação na posição das espécies na tabela de fitossociologia, mas mesmo assim há um alto viés para espécies de baixa densidade e uma grande alteração na posição das espécies na tabela de fitossociologia. Com relação à distribuição espacial, espécies com densidades intermediárias têm suas estimativas mais influenciadas pela distribuição espacial do que aquelas com baixa densidade - que sempre apresentarão viés - e aquelas com alta densidade - que não apresentam viés devido ao alto número de invivíduos na amostra. As análises de tributos de comunidade mostraram que esses atributos podem ser bem estimados, levando-se em consideração apenas detalhes usuais da escolha de método para qualquer amostragem, como o número de unidades amostrais, seu tamanho e sua distribuição pela área de estudo.Many methodologies are available for phytosociological studies, and many attempts have been made to evaluate them. The most commonly used method employs sample plots. This technique is always referred to in the literature as the basic approach and, as such, is usually defined as the benchmark to which the other methods are compared. For this reason, it has never been evaluated on its own. This work presents the opportunity to evaluate the plot method itself and compare its results with the parametric values available from a full census of a sampling area in which the complete population data is known and contains no sampling error. Data was taken from a permanent plot located in an area of forested savannah (Assis Ecological Station, SP, Brazil), that comprises an area of 10.24 ha, and all trees over 15 cm girth at breat hight were marked, georeferenced, measured and identified. Phytosociological measures were computed with the values of density and basal area for each species in the census and represent the parametric values. Simulations were made of phytosociological surveys by sistematic sampling with four square plot sizes (10 x 10 m, 20 x 20 m, 50 x 50 m, and 100 x 100 m). Additionally, three sampling intensities were simulated for the 10x10m plots (75, 50, and 25 plots). One thousand simulated surveys were performed for each sampling situation, and for each of these surveys phytosociological measures were computed. The bias in the estimates of both density and dominance was evaluated, as well as change in species importance. The influence of spatial pattern on the estimation of phytosociological measures was also evaluated. At last, some analysis of community attributes, that are feasible with phytosociological measures were made, such as density, basal area, species acummulation curves, number of species sampled and propotion of species and individuals per density group. The 10 x 10 m sample plots showed the lowest overall bias and the lowest variation in species importance, but even in this method were observed high bias and high variation. About the spatial distribution, species with very low density showed very large bias, indenpendently of spatial pattern. Spatial pattern had a clear influence on the estimates of intermediate density species, where species with more clustered pattern showed more skewed distribution. And for the species with high density, spatial pattern does not seem to play an importante role. The community attributes analysed can be well estimated with phytosociolocical measures, just taking into consideration some usual methodological details, such as sampling size and plot distributions within the study area.
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Hervé, Maxime. "Écologie chimique de l'interaction colza - méligèthe : vers de nouvelles stratégies de contrôle des insectes ravageurs ?" Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S070/document.
Testo completoAbstract (sommario):
Les plantes possèdent de multiples systèmes de défense contre les insectes phytophages. Dans un contexte agronomique, manipuler ces défenses au moyen de la sélection pourrait contribuer à réduire les dommages causés par les insectes ravageurs en augmentant la résistance naturelle des plantes. Cette stratégie se heurte cependant à des contraintes très fortes lorsqu'il s'agit de l'appliquer aux insectes. Après avoir détaillé ces contraintes, nous proposons une démarche alternative aux méthodes classiques. Celle-ci vise à identifier des traits-clés de la plante qui modulent son interaction avec le ravageur. Si de tels traits sont identifiés et validés expérimentalement, ils permettront ensuite de conduire la sélection sans nécessiter d'insecte. Nous avons testé cette démarche dans un système composé du colza (Brassica napus) et du méligèthe Meligethes aeneus, un ravageur majeur de cette culture. Le méligèthe est un coléoptère pollinivore dont les adultes sont généralistes mais ne pondent que sur certaines brassicacées. Les dégâts agronomiques sont causés par ces adultes qui, avant que la floraison ne démarre, détruisent les boutons floraux pour atteindre le pollen qu'ils contiennent. Quatre étapes cruciales de l'interaction ont été étudiées : l'attraction à distance, l'alimentation des adultes, la production et la ponte des œufs, et le développement larvaire. Six génotypes de colza ont été comparés dans une série d'expérimentations au laboratoire. La mise en relation des résultats de préférence/performance de l'insecte avec des profilages métaboliques larges de tissus floraux a permis d'identifier des traits-clés candidats. Les conclusions principales de ce travail sont (i) que la composition biochimique du périanthe est déterminante dans la stimulation de l'alimentation des adultes, et que cette stimulation pourrait être largement sous l'influence d'un petit nombre de composés dont le saccharose ; (ii) que cette stimulation détermine de façon majeure, par un effet domino, la production d'œufs en contraignant l'ovogenèse ; (iii) que la qualité nutritionnelle du pollen impacte à la fois les larves et les adultes, et que cette qualité pourrait être déterminée en bonne partie par la concentration en amidon et en certains glucosinolates (des métabolites secondaires typiques de quelques familles végétales dont les brassicacées). La combinaison des différents résultats obtenus permet également de proposer des hypothèses plus générales, parmi lesquelles le fait que le contexte agronomique dans lequel l'interaction a lieu ait largement influencé, voire perturbé, l'interaction qui liait le méligèthe et les brassicacées sauvages avant que les cultures de colza ne se généralisent. Cette thèse a montré qu'une nouvelle voie était peut-être envisageable pour contribuer à protéger les cultures de façon durable contre les insectes ravageurs, en particulier pour les systèmes agronomiques où les dégâts sont causés à un stade temporairement sensible de la culturePlants display multiple defense systems against phytophagous insects. Manipulating these defenses by means of selection could contribute to decrease damages caused by insect pests, by increasing natural resistance of crops. This strategy faces great constraints when applied to insects. We first detail these constraints and then propose an alternative approach to classical methods. It consists in identifying key plant traits that determine the intensity of the interaction between the plant and the pest. If such traits are identified, selection could be conducted on the basis if these sole traits, without needing any insect. We tested this approach in a system composed of oilseed rape (Brassica napus) and the pollen beetle (Meligethes aeneus), a major pest of this culture. This coleopteran generalist pollen feeder lays eggs only on certain brassicaceous plants. Agronomical damage arise before plant flowering and are caused by adults, which destroy flower buds to get the pollen they contain. Four crucial steps of the interaction were studied: attraction, adult feeding, egg production and oviposition, and larval development. Six oilseed rape genotypes were compared in a series of experiments conducted in the laboratory. By linking insect preference/performance to large metabolic profiling of bud tissues, we identified candidate key traits. Main conclusions of this work are (i) that biochemical composition of the perianth, especially a few compounds among which sucrose, is determinant for feeding intensity; (ii) that feeding stimulation has an important impact on egg production by constraining oogenesis; (iii) that pollen nutritional quality, probably mostly determined by starch and some glucosinolates, interacts with both pollen beetle larvae and adults. Combination of several results also allows drawing more general hypotheses about the oilseed rape - pollen beetle interaction. One of these is that the agronomical context in which the interaction takes place may have largely influenced, or even disturbed, the interaction that linked this insect and wild brassicaceous plants before oilseed rape cultivation. This thesis showed that a new way might be possible to protect cultures against insect pests. It could be both efficient and sustainable, especially in systems where agronomical damage is caused at a temporary vulnerable plant stage
35
Derkintienė, Loreta. "Neries regioninio parko vabzdžių, įtrauktų į Raudonąją knygą, analizė". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090615_114805-46105.
Testo completoAbstract (sommario):
Magistro darbe tiriami Neries regioninio parko vabzdžiai , įtraukti į Raudonąją knygą. Darbo objektas- niūriaspalvis auksavabalis (Osmoderma eremita Sc.) , gencijoninis melsvys (Makulinea alcon D.& S.), Darbo tikslas- ištirti kai kurių vabzdžių , įtrauktų į Raudonąją knygą, paplitimą ir gausumą Neries regioniniame parke. Darbo metodai - duomenys buvo renkami naudojantis P.Ivinskio ir J.Rimšaitės bestuburių monitoringo metodika . Darbo rezultatai. Atlikus tyrimus ir įvertinus nustatyta , kad niūriaspalvis auksavabalis (Osmoderma eremita) labiau mėgsta senus , drevėtus , gerai apšviestus medžius. Labiausiai jam tinkamas ąžuolas. Gencijoninis melsvys (Makulinea alcon D.& S.), dažniausiai aptinkamas pietiniuose , gerai apšviestuose šlaituose ,kur vyrauja žema žolinė danga. Būtina sąlyga- augalai melsvieji gencijonai (Gentiana cruciata) ir Myrmica genties skruzdėlės Norint užtikrinti palankias sąlygas niūriaspalviam auksavabaliui , būtina išsaugoti kertines miško buveines ir senus , drevėtus medžius. Norint išsaugoti gencijoninį melsvį būtina prižiūrėti populiacijai tinkamus upių šlaitus ,neleidžiant užaugti aukštai žolinei dangai ir krūmams.In the master’s of science work the Neris regional park’s insects included in the Red Book are being researched. The object of the work is Osmoderma eremite Sc. and gentian lycaena (Makulinea alcon D.& S.). The objective of the work is to research the diffusion and abundance of some insects included in the Red Book in the Neris regional park. The methods of the work. The data had been collected by using P. Ivinskis and J. Rimšaite methods of invertebrates‘ monitoring. After the research was carried out and the facts estimated, it was established that Osmoderma eremite prefers old, hollow and well-lighted up trees. Oak tree is the most suitable one. Gentian lycaena ( Makulinea alcon D. & S.) is most frequently discovered in southern, well-lighted up slopes where low grass prevails. Gentiana cruciata and ants of Myrmica genus are an indispensable condition. If one wishes to ensure auspicious conditions for Osmoderma eremite Sc., it is necessary to preserve the most important for them forestry habitats and old hollow trees. If one wishes to preserve gentian lycaena, it is necessary to look after river slopes suitable for the population not allowing to grow tall grass and bushes.
36
Bothamy, Nina. "Fractionnement anthropique et naturel des isotopes stables du néodyme (Nd) dans l'environnement". Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0295.
Testo completoAbstract (sommario):
Avec une utilisation mondiale croissante pour des applications variées (nouvelles technologies, énergies vertes, etc.), les terres rares (REEs pour ‘rare earth elements’) sont devenues des polluants émergents. Ces pollutions peuvent/pourront être d’origine industrielle (ex. rejets dans l’environnement en sortie d’usine), minière, ou causées par le stockage inapproprié de produits industriels (ex. aimants à base de néodyme (Nd) fragiles à la corrosion). Dans ce contexte, ce projet de thèse a cherché à développer un nouvel outil : l’étude du fractionnement dépendant de la masse des isotopes du Nd (δNd en ‰). Les objectifs de ce projet ont été i) d’apporter un maximum d’éléments pour aider à tracer les pollutions anthropiques de Nd dans l’environnement et ii) d’aider à mieux comprendre comment fonctionne l’accumulation des REEs par les plantes, en particulier les fougères hyperaccumulatrices Dicranopteris linearis, dans le but d’appuyer les études de phytoremédiation des sites pollués. Le δNd de matériels anthropiques (solutions synthétiques de Nd pur et aimants industriels Nd2Fe14B) a été mesuré (gamme de variation de 1,45 ‰ en δ148Nd, littérature incluse) et comparé à la signature des roches terrestres de la littérature (gamme de 0,66 ‰). Les résultats montrent que l’utilisation combinée i) du rapport de l’isotope radiogénique 143Nd/144Nd (ε143Nd, traceur de sources), ii) de la composition des isotopes stables du Nd (δNd, traceur de sources et processus) et, iii) du type de fractionnement (cinétique ou à l’équilibre thermodynamique) des isotopes stables du Nd, peut permettre à l’avenir de distinguer le Nd naturel du Nd anthropique et de tracer ce Nd anthropique dans l’environnement. La mesure du δNd de 5 spécimens de fougères D. linearis, ainsi que de 3 standards biologiques (lichen, feuilles de pommes et lentilles d’eau) a permis de déterminer de façon évidente que la biologie peut fractionner les isotopes stables du Nd. Les valeurs extrêmes en δ148Nd, parmi les échantillons biologiques, sont -0,415 ± 0,060 ‰ et -0,011 ± 0,022 ‰ (2σmean), respectivement pour l’une des pétioles des fougères et pour les lentilles d’eau. Trois résultats principaux en découlent : i) le fractionnement des isotopes stables (δNd) est corrélé au fractionnement des REEs légères par rapport aux REEs lourdes pour tous les échantillons mesurés (fougères, lichen, feuilles de pomme, lentilles d’eau et tous les sols) ; ii) le transport et la distribution du Nd (et des REEs) dans les différentes parties des fougères sont corrélés à ceux du manganèse (Mn), suggérant un mécanisme de transport similaire des REEs et du Mn, pour les fougères mais aussi chez d’autres végétaux comme les pommiers ; iii) la dégradation de l’argile, sur laquelle les REEs sont massivement adsorbées dans les sols étudiés, peut induire le fractionnement des isotopes stables du Nd des sols, que ce soit une dégradation causée par des processus naturels (ex. biologie) ou anthropiques (extraction des REEs avec des acides miniers)With the worldwide growing demand for various applications (new technologies, green energies, etc.), rare earth elements (REEs) are now considered as emerging pollutants. These pollutions are/will be of industrial origin (e.g. industrial wastes), of mining origin, or caused by the inappropriate storage of industrial products (e.g. neodymium (Nd) magnets fragile against corrosion). In this context, this PhD project aims to develop a new tool: the study of the mass-dependent isotopic fractionation of Nd (δNd in ‰). The goals of this work were to i) bring the maximum of information in order to help to identify and trace anthropogenic Nd in the environment, and ii) help the understanding of how plants accumulate REEs, especially the hyperaccumulator Dicranopteris linearis ferns, in order to support the studies about the phytoremediation of polluted areas. The δNd of anthropogenic materials (pure Nd synthetic solutions, Nd2Fe14B industrial magnets; δ148Nd range of 1.45 ‰, literature included) was compared to the signature of natural terrestrial rocks of the literature (δ148Nd range of 0.66 ‰). Our results show that the use together of i) the 143Nd radiogenic isotope (ε143Nd, tracer of sources), ii) the stable Nd isotopic composition of Nd (δNd, tracer of sources and processes) and, iii) the kind of stable Nd isotopic fractionation (kinetic or thermodynamic equilibrium), could allow the distinction of the natural from the anthropogenic Nd, and to trace the anthropogenic Nd in the environment. The measurement of the δNd of 5 D. linearis fern specimens, and of 3 biological standards (lichen, apple leaves and duck weed) allowed discovering that biology can fractionate the stable Nd isotopes. Extreme δ148Nd values are -0.415 ± 0.060 ‰ and -0.011 ± 0.022 ‰ (2σmean), respectively for one of the fern petiole and the duck weed. Three principal results were obtained: i) the δNd fractionation is correlated to the fractionation of the light REEs than the heavy REEs for all the studied samples (ferns, lichen, apple leaves, duck weed and all soil materials); ii) the distribution and transport of Nd (and REEs) in the different parts of ferns are correlated to those of manganese (Mn), suggesting similar transport mechanisms for REEs and Mn, for ferns but also for other plants as apple trees; iii) the degradation of clay minerals, on which REEs are mostly adsorbed in the studied soils, can induce the fractionation of stable Nd isotopes, from natural processes (e.g. biological) or anthropogenic processes (REEs mining acidic extraction)
37
Louis, Pauline. "Origine, comportement et devenir des Terres Rares dans les installations de traitements des eaux résiduaires urbaines et les milieux récepteurs associés". Electronic Thesis or Diss., Université de Lorraine, 2021. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2021_0021_LOUIS.pdf.
Testo completoAbstract (sommario):
Les Terres Rares (REE) sont naturellement présentes dans les eaux du fait de l’érosion des roches. Elles sont également employées dans des activités anthropiques (nouvelles technologies, énergies, agriculture et médecine). Ces utilisations en constante augmentation ont fini par perturber le cycle géochimique et biologique des REE et ont mené à l’enrichissement (anomalie positive) de certaines REE dans l’hydrosphère (La, Ce, Sm et Gd). Pour le Gdanth, la pollution provient des stations de traitements des eaux usées conventionnelles (STEU) qui ne sont pas en mesure d'éliminer la forme complexe organique de Gd utilisée dans l'analyse IRM. Quatre ensembles ont donc été étudiés afin de mieux connaître le comportement des REE : le bassin français de la Moselle, le bassin du Danube dans son ensemble, la STEU du Grand Nancy, et la zone de rejet végétalisée (ZRV) en aval de la STEU du Grand Reims. Le long de la Moselle, la présence d'anomalies positives en Gd et un appauvrissement régulier des LREE comparativement aux HREE enrichies sur les spectres de REE sur des substrats de grès/calcaire sont les points les plus caractéristiques. Dans le bassin du Danube, l’anomalie positive en Gd varie de 1,8 à 37,4 dans les eaux de surfaces et jusqu’à 80,8 dans les eaux souterraines, montrant une contamination des puits alluviaux. Au sein de la STEU du Grand Nancy, les flux entrant de Gd ont montré être plus importants en semaine (mardi et mercredi), et aux heures de fin de journée (19h-22h). Les procédés de traitement n’affectent pas le Gdanth, mais augmentent le fractionnement LREE/HREE. Les eaux de la ZRV sont celles qui présentent les plus fortes valeurs d’anomalies positives en Gd (jusqu’à 4500). Il a été démontré que l'ampleur des anomalies Gd dépendait de l'approche méthodologique choisie pour leur calcul. La définition d'une valeur seuil pour identifier la présence d'une anomalie anthropique Gd peut donc dépendre du bassin, et se révéler délicate dans les zones où la pression anthropique est faibleRare Earths Elements (REEs) are naturally present in water due to the erosion of rocks. They are used in human activities (new technologies, energy, agriculture and medicine). These ever-increasing uses eventually disrupted the geochemical and life cycle of REEs and led to the enrichment (positive anomaly) of some REEs in the hydrosphere (La, Ce, Sm and Gd). For anthropogenic Gd, pollution derives from conventional wastewater treatment plants (WWTPs) which are not able to remove the organic complex form of Gd used in MRI analyses. Four areas were therefore studied in order to better understand the behavior of the REEs: the French basin of the Moselle River, the Danube river basin as a whole, the WWTP of Grand Nancy, and the constructed wetland downstream the WWTP of Grand Reims. Along the Moselle River, the presence of positive Gd anomalies and a regular LREEs depletion/ HREEs enrichment pattern on sandstone/limestone substrates were the most distinctive features. In the Danube basin, the positive Gd anomaly ranged from 1.8 to 37.4 in surface water and up to 80.8 in groundwater, showing contamination of alluvial wells. Within the Greater Nancy STEU, the greatest Gd inflows were observed during weekdays (Tuesday and Wednesday), and at the end of the day (7 p.m. to 10 p.m.). Treatment processes did not affect anthropogenic Gd, but increased LREE/HREE fractionation. The waters of the artificial wetland were those with the highest values of positive Gd anomalies (up to 4500). It was shown that the magnitude of Gd anomalies depended on the methodological approach chosen for their calculation. The choice of a threshold value to identify the presence of an anthropogenic Gd anomaly may therefore be basin dependent and may be tricky in areas where anthropogenic pressure is low
38
Fiebelkorn, Wrucke Danielle. "Genetic Analysis of Frost Tolerance in Rapeseed/Canola (Brassica Napus L.)". Diss., North Dakota State University, 2017. https://hdl.handle.net/10365/28362.
Testo completoAbstract (sommario):
Frost can be detrimental to canola (Brassica napus L.) production. Depending on the severity, the entire field can be killed. Having frost tolerance in canola would benefit growers by allowing them to plant early, utilize early season moisture, and avoid high heat during flowering. However, frost tolerance in canola has not been well studied. A protocol was developed that determined 14 day old seedlings should be acclimated at 4?C for 7 days before being exposed to overnight frost (-4?C) in a small freezing chamber. However, when a larger chamber was used for freezing, the protocol was optimized to -8?C instead. A greenhouse study was conducted on a diverse collection of 231 genotypes and genome-wide association scan (GWAS) was conducted to identify potential genes that were related to frost tolerance or abiotic stress tolerance. Thirty-eight significant single nucleotide polymorphism (SNP) markers were selected based on 10,000 bootstraps and 0.1 percent tail of the empirical distribution. The markers were located on chromosomes A01, A02, A03, A04, A07, A08, A09, A10, C03, C05, C06, C07, and C09. Stepwise regression highlighted a QTL located on chromosomes A02. Another GWAS was done on 147 canola germplasm lines phenotyped under natural conditions. Thirty-eight significant SNPs identified from this study were located on chromosomes A05, A07, A09, C01, C02, C03, C04, C05, C06, C07, and C09. Stepwise regression identified a QTL located on chromosome C04. A protocol was developed to measure the freezing induced electrolyte leakage from leaves of rapeseed/canola. A total of 157 germplasm lines were evaluated for freezing induced (-12?C for 2 h) electrolyte leakage. Thirty-six significant SNPs located on chromosomes A01, A02, A03, A04, A05, A06, A07, A08, A09, A10, C01, C02, C04, C05, C06, C07, and C09 were identified. Stepwise regression identified 10 QTL located on chromosomes A01, A02, A04, A06, A07, C02, C05, C07, C09, and one that could not be assigned. All GWAS studies identified potential genes of interest that were related to frost tolerance, abiotic stress, and transcription factors.Northern Canola Growers Association
39
Swart, Carin. "Life history, population dynamics and conservation status of Oldenburgia grandis (Asteraceae), an endemic of the Eastern Cape of South Africa". Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1003799.
Testo completoAbstract (sommario):
Oldenburgia grandis is a rare, long-lived woody paleoendemic of the Fynbos Biome of South Africa. Confined to quartzite outcrops, it has a small geographic range and narrow habitat specificity. O. grandis responds to its fire-prone environment by resprouting. Elasticity analysis of O. grandis reveals that growth and fecundity were traded off for persistence of adult, mature and sapling stages. Morphological adaptations such as a corky fire-resistant bark and the ability to resprout after fire are traits that O. grandis have evolved to persist in a frequently disturbed environment. Population growth rate for sites undisturbed by fire for a number of years (l = 1.01) and sites at various stages of recovery after fire (l = 1.00) were very similar. The highest variation in transition probabilities for all sites was seen in the persistence of the seedling stage and growth from seedling to sapling. Observed population structure and stable stage distribution determined by the matrix model show that sites recently undisturbed by fire had high abundances of the adult and sapling stages. A peak in sapling stages was seen for the stable stage distribution where similar peak in sapling numbers were seen for population structures of sites at various stages of recoveryafter fire. Favourable environmental conditions for the persistence of O. grandis populations include no fire with transition probabilities between the observed minimum and maximum and fire frequency at a 10 year interval where seedling protection from the fire is high and adult and mature mortalities during the fire are low. Stochastic environmental events that could put populations (particularly small populations) at an increased risk of extinction include high to moderate fire intensities where seedling protection from the fire is low and adult and mature mortalities are high as a result of the fire.
40
Ye, Zhengqian. "Effect of low temperature on boron nutrition of oilseed rape and sunflower". Thesis, Ye, Zhengqian (2004) Effect of low temperature on boron nutrition of oilseed rape and sunflower. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/418/.
Testo completoAbstract (sommario):
Several reports appear in the literature linking low temperature damage in plants with boron (B) deficiency and alleviation of low temperature injury with B application has been reported in some crops and trees. These results imply that low temperature might increase plant B requirements, beside the reduction of B uptake by plant roots, or that low B tissues might be more sensitive to cold temperature damage than B adequate tissues. In controlled experiments, it has been shown that low root zone temperature (RZT) induces B deficiency in cassava, a tropical root crop. Apart from this, there are few definitive detailed investigations on low temperature effects on B nutrition of plants, including temperate species which are more tolerant of low temperature.
Winter oilseed rape (Brassica napus L.), a crop sensitive to low B supply, is a major crop in the middle and lower Yangtse river basin, China, where low B soils are widespread. Appearance of B deficiency in oilseed rape often coincides with cold weather during its winter and spring growth. However, the incidence and severity of B deficiency of oilseed rape plants and the efficacy of B fertilization varies from year to year and location to location in ways that are not explained simply by differences in cultivar, agronomy or soil B levels. Low temperature is probably one of the important environmental factors influencing growth and yield of oilseed rape in relation to B nutrition.
Therefore,the objective of the studies in this thesis was to investigate mechanisms of low temperature effects on B nutrition of plants with emphasis on oilseed rape. Field and glasshouse experiments were carried out and the physiological basis of plant response to B at different air and root temperatures is discussed.
A field experiment with oilseed rape cv. Zheyouyou 2 was carried out on a red soil (Hapludult, US Soil Taxonomy) with low B availability in Zhejiang province, China. Canopy covers made from transparent plastic sheets, which increased night temperatures by up to 1.5 oC around shoots for 15 days in early February, strongly increased shoot dry weight at all levels of B supply. Furthermore, covering plants increased shoot dry weight of B deficient plants without increasing their leaf B concentration. This suggests that internal B requirements were decreased by canopy covering, possibly due to higher temperatures within the canopy.
Experiments conducted to investigate the effect of RZT (10 and 20 oC) on oilseed rape cv. Hyola 42 response to B in solution culture, in summer and winter, showed that regardless of canopy conditions, low RZT (10 oC) promoted the distribution of shoot B towards the actively growing leaves, especially when B supply was low. At low B supply, B deficiency symptoms appeared later at 10 oC than 20 oC RZT and B concentrations in the youngest fully opened leaves (YOL) were higher in plants grown at RZT of 10 oC than that at 20 oC. Growth of plant dry weight (DW) was not affected by RZT in the summer but was greatly reduced at 10 oC than 20 oC in winter. In B adequate plants, shoot to root ratio (S/R ratio) was not affected by RZT regardless of canopy conditions. By contrast, S/R ratio was smaller in low B plants at 10 oC than 20 oC. In addition, low RZT delayed occurrence of plant B deficiency symptoms regardless of plants' pre-treatment RZT (either 10 or 20 oC). These results appeared to contradict the response to low RZT found in previous studies with cassava.
In a subsequent experiment, low RZT of 5 oC not only greatly reduced plant DW production of oilseed rape, but also accentuated plant B deficiency. Partitioning of B into the young growing shoots was also depressed and a significant decrease of B concentration in the youngest shoot parts was caused by 5 oC RZT in comparison with that at the control RZT (10 oC). Similar results were also observed in sunflower (Helianthus annuus L. cv. Hysun 25). But B deficiency symptoms in sunflower were induced by RZT as high as 12 oC, when plants were supplied with 0.25 mcg B, whilst these plants were free from B deficiency at warmer RZT (17 - 27 oC). Higher external B concentrations were required at such RZT (Chilling temperature) for plant growth free from B deficiency. Therefore, there is a RZT threshold below which an increased response to B is expected in plants of oilseed rape and sunflower. And in the range of chilling RZT, the external B requirement for shoot growth increased with lower RZT. The threshold RZT was considerably higher in the chilling-sensitive plant species, sunflower, than in oilseed rape, a chilling-resistant plant species.
At chilling RZT, leaf functioning was impaired by low B supply as measured by potassium (K) leakage from the youngest mature leaf blade (YML) of sunflower, whereas it was much less directly affected by RZT, and there was no effect of RZT on B- adequate plants. By contrast to leaves, root function was impaired more by chilling RZT than low B.
Despite their different threshold RZT, in both oilseed rape and sunflower, the rates of B uptake (BUR) and B translocation from root to shoot (BTR) were dramatically depressed by chilling RZT especially at low B supply (0.2 mcg B): being only 30% of those at the control (5 oC vs 10 oC RZT) in oilseed rape and 33% (10 oC vs 20 oC RZT) in sunflower, respectively. By contrast, there was little or no difference over a range of warmer RZT (10 - 20 oC for oilseed rape, and 20 - 27 oC for sunflower). It is predicted that higher rates of B application will be required for plant growth when soil temperature is below a critical threshold, which is between 5 and 10 oC for oilseed rape, and about 17 oC for sunflower, respectively. Below the threshold RZT plant B deficiency was induced and accentuated due to impairment of B translocation into growing shoot parts besides the decrease of B uptake rate and B transport rate and greater shoot to root ratio.
In comparison with RZT, little is known about causal mechanisms linking cold air temperature and B nutrition. Experiments in this thesis showed not only B transport to the shoot was strongly reduced by low night air temperature during a 6 day period (11.719.4 vs 15.5 - 23.5 oC), but also that an overnight chilling (at 0 oC) could cause more severe injury to low B than adequate B leaves of oilseed rape plants, expressed by higher solute leakage, in comparison with control (at 10 oC). Moreover, after chilling treatment, solute leakage from low B leaves was increased by exposure to light, which suggests that low temperature injury to leaves in low B plants after a freezing night in the field is at least partly a consequence of light induced damage of leaves.
In summary, at chilling temperature, B uptake, transport and partitioning into growing shoots are strongly impaired, and B use efficiency in the growing tissues might be reduced as well. Low temperature contributes to plant B deficiency also by increasing S/R ratio, so that shoot B demand is not satisfied by available B. Furthermore, low air temperature might increase the internal B requirement for shoot growth. To further understand mechanisms of low temperature, especially the air temperature, effects on plant responses to B, more research is needed, such as the relationship between low temperature and B incorporation into cell walls which may play an important role in leaf tolerance to chilling temperature.
41
Ye, Zhengqian. "Effect of low temperature on boron nutrition of oilseed rape and sunflower". Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060510.154332.
Testo completoAbstract (sommario):
Several reports appear in the literature linking low temperature damage in plants with boron (B) deficiency and alleviation of low temperature injury with B application has been reported in some crops and trees. These results imply that low temperature might increase plant B requirements, beside the reduction of B uptake by plant roots, or that low B tissues might be more sensitive to cold temperature damage than B adequate tissues. In controlled experiments, it has been shown that low root zone temperature (RZT) induces B deficiency in cassava, a tropical root crop. Apart from this, there are few definitive detailed investigations on low temperature effects on B nutrition of plants, including temperate species which are more tolerant of low temperature.
Winter oilseed rape (Brassica napus L.), a crop sensitive to low B supply, is a major crop in the middle and lower Yangtse river basin, China, where low B soils are widespread. Appearance of B deficiency in oilseed rape often coincides with cold weather during its winter and spring growth. However, the incidence and severity of B deficiency of oilseed rape plants and the efficacy of B fertilization varies from year to year and location to location in ways that are not explained simply by differences in cultivar, agronomy or soil B levels. Low temperature is probably one of the important environmental factors influencing growth and yield of oilseed rape in relation to B nutrition.
Therefore,the objective of the studies in this thesis was to investigate mechanisms of low temperature effects on B nutrition of plants with emphasis on oilseed rape. Field and glasshouse experiments were carried out and the physiological basis of plant response to B at different air and root temperatures is discussed.
A field experiment with oilseed rape cv. Zheyouyou 2 was carried out on a red soil (Hapludult, US Soil Taxonomy) with low B availability in Zhejiang province, China. Canopy covers made from transparent plastic sheets, which increased night temperatures by up to 1.5 oC around shoots for 15 days in early February, strongly increased shoot dry weight at all levels of B supply. Furthermore, covering plants increased shoot dry weight of B deficient plants without increasing their leaf B concentration. This suggests that internal B requirements were decreased by canopy covering, possibly due to higher temperatures within the canopy.
Experiments conducted to investigate the effect of RZT (10 and 20n oC) on oilseed rape cv. Hyola 42 response to B in solution culture, in summer and winter, showed that regardless of canopy conditions, low RZT (10 oC) promoted the distribution of shoot B towards the actively growing leaves, especially when B supply was low. At low B supply, B deficiency symptoms appeared later at 10 oC than 20 oC RZT and B concentrations in the youngest fully opened leaves (YOL) were higher in plants grown at RZT of 10 oC than that at 20 oC. Growth of plant dry weight (DW) was not affected
by RZT in the summer but was greatly reduced at 10 oC than 20 oC in winter. In B adequate plants, shoot to root ratio (S/R ratio) was not affected by RZT regardless of canopy conditions. By contrast, S/R ratio was smaller in low B plants at 10 oC than 20 oC. In addition, low RZT delayed occurrence of plant B deficiency symptoms regardless of plants¡¦ pre-treatment RZT (either 10 or 20 oC). These results appeared to contradict the response to low RZT found in previous studies with cassava.
In a subsequent experiment, low RZT of 5 oC not only greatly reduced plant DW production of oilseed rape, but also accentuated plant B deficiency. Partitioning of B into the young growing shoots was also depressed and a significant decrease of B concentration in the youngest shoot parts was caused by 5 oC RZT in comparison with that at the control RZT (10 oC). Similar results were also observed in sunflower (Helianthus annuus L. cv. Hysun 25). But B deficiency symptoms in sunflower were induced by RZT as high as 12 oC, when plants were supplied with 0.25 £gM B, whilst these plants were free from B deficiency at warmer RZT (17 - 27 oC). Higher external B concentrations were required at such RZT (Chilling temperature) for plant growth free from B deficiency. Therefore, there is a RZT threshold below which an increased response to B is expected in plants of oilseed rape and sunflower. And in the range of chilling RZT, the external B requirement for shoot growth increased with lower RZT. The threshold RZT was considerably higher in the chilling-sensitive plant species, sunflower, than in oilseed rape, a chilling-resistant plant species.
At chilling RZT, leaf functioning was impaired by low B supply as measured by potassium (K) leakage from the youngest mature leaf blade (YML) of sunflower, whereas it was much less directly affected by RZT, and there was no effect of RZT on B- adequate plants. By contrast to leaves, root function was impaired more by chilling RZT than low B.
Despite their different threshold RZT, in both oilseed rape and sunflower, the rates of B uptake (BUR) and B translocation from root to shoot (BTR) were dramatically depressed by chilling RZT especially at low B supply (0.2 £gM B): being only 30% of those at the control (5 oC vs 10 oC RZT) in oilseed rape and 33% (10 oC vs 20 oC RZT) in sunflower, respectively. By contrast, there was little or no difference over a range of warmer RZT (10 - 20 oC for oilseed rape, and 20 ¡V 27 oC for sunflower). It is predicted that higher rates of B application will be required for plant growth when soil temperature is below a critical threshold, which is between 5 and 10 oC for oilseed rape, and about 17 oC for sunflower, respectively. Below the threshold RZT plant B deficiency was induced and accentuated due to impairment of B translocation into growing shoot parts besides the decrease of B uptake rate and B transport rate and greater shoot to root ratio.
In comparison with RZT, little is known about causal mechanisms linking cold air temperature and B nutrition. Experiments in this thesis showed not only B transport to the shoot was strongly reduced by low night air temperature during a 6 day period (11.719.4 vs 15.5 ¡V 23.5 oC), but also that an overnight chilling (at 0 oC) could cause more severe injury to low B than adequate B leaves of oilseed rape plants, expressed by higher solute leakage, in comparison with control (at 10 oC). Moreover, after chilling treatment, solute leakage from low B leaves was increased by exposure to light, which suggests that low temperature injury to leaves in low B plants after a freezing night in the field is at least partly a consequence of light induced damage of leaves.
In summary, at chilling temperature, B uptake, transport and partitioning into growing shoots are strongly impaired, and B use efficiency in the growing tissues might be reduced as well. Low temperature contributes to plant B deficiency also by increasing S/R ratio, so that shoot B demand is not satisfied by available B. Furthermore, low air temperature might increase the internal B requirement for shoot growth. To further understand mechanisms of low temperature, especially the air temperature, effects on plant responses to B, more research is needed, such as the relationship between low temperature and B incorporation into cell walls which may play an important role in leaf tolerance to chilling temperature.
42
Vilkinytė, Dovilė. "Saugomosios retosios augalu rusys Balkasodzio botaniniame draustinyje". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090615_114653-24626.
Testo completoAbstract (sommario):
Magisto darbe tiriama Balkasodžio botaninio draustinio saugomų ir retų augalų būklė ir gamtosauginė svarba. Magistro baigiamąjį darbą sudaro 69 puslapiai. Jame yra lentelės, paveikslėliai, literatūros šaltiniai ir priedai.
Darbo objektas – Vėjalandės šilagėlės (Pulsatilla patens), plikažiedžio linlapio (Thesium ebracteatum), smiltyninio gvazdiko (Dianthus arenarius) ir kitų rūšių radimvietės Balkasodžio botaniniame draustinyje.
Darbo tikslas – Nustatyti į ES buveinių direktyvos II priedą įrašytų rūšių: vėjalandės šilagėlės (Pulsatilla patens), plikažiedžio linlapio (Thesium ebracteatum) , smiltyninio gvazidiko (Dianthus arenarius) – populiacijų apsaugos būklę. Šios rūšys, LRK paskutinių metų duomenimis, priskirtos 2 (V) saugomų augalų kategorijai.
Darbo metodai – Buvo vykdomi lauko darbai ir floros inventorizacija. Nustatytos retų ir saugomų augalų rūšių radimvietės, fiksuojamos rastos floros rūšys, apibūdintos jų augavietės. Tyrimui pasirinktas maršrutinis apžiūros ir įvertinimo metodas.
Darbo rezultatai - Norūnų miško saugomoje teritorijoje, kurios plotas sudaro 243 ha, užregistruota 471 induočių augalų rūšis. Iš jų 451 rūšies yra savaiminiai ir 20 rūšių svetimžemiai augalai. Teritorijoje aptikta 11 rūšių, įrašytų į LRK, tarp jų 3 induočių augalų rūšys įrašytos į ES buveinių direktyvos II priedą.
Didžiausios teritorijoje esančios vertybės yra retosios, į ES buveinių direktyvos II priedą įrašytos rūšys – vėjalandė šilagėlė (Pulsatilla patens), plikažiedis linlapis... [toliau žr. visą tekstą]The study is intended to analyse the rare and protected plants state and ecological reserve importance in Balkasodis reserve. Final master degree work of university, pages, figures, tables, references, appendix. The object - The rare and protected plants in Balkasodis reserve. The objects for the research plants included in The Red Data Book of Lithuania and which is growing in the botanical reserve of Balkasodis (Alytus region). This botanical reserve was opened in 1992. The aim - Implementing the previsions of the European Union Habitat Directive in Lithuania, on the most important task is to evaluate the state of the three plant species, included in the Annex 2 of the EU Habitat Directive. Dianthus arenarius, Pulsatilla patens, Thesium ebracteatum, during their vegetation period in the year 2008 and to suggest effective measure for their protection. According to the latest facts of the Lithuanian Red Data Book these three plant species are ascribed to the 2 (V) category of the legally protected species. The methods – Outside works and flora invetorization were carried out. Places where rare and protected plants grow were defined as well as all discovered flora species were recorded and described. The results - At the time of the research in the botanical reserve of Balkasodis were found 471 plant species: 451 plants are locals and 20 plant species are other. In the area were found 11 species of sparse plants (plants included in The Red Book of Lithuania). ... [to full text]
43
Stangoulis, James Constantine Roy. "Genotypic variation in oilseed rape to low boron nutrition and the mechanism of boron efficiency". Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phs7856.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 132-159. Boron efficiency in oilseed rape (Brassica napua L. and B. juncea L.) was investigated in a wide range of genotypes. Using a solution culture screening of 10 day old seedlings, root length best described shoot growth response, and was used to characterise a total of 65 genotypes. Varieties and breeders lines tolerant of B-deficient growing conditions were identified, and the screening process validated through field trials. B responses in plants sampled at the 'green bud' stage indicated that vegetative growth is important in B efficiency. Studies were conducted to investigate the mechanism of B efficiency in oilseed rape. Results suggest no association between B efficiency and the capacity to acidify the root rhizosphere, or an increased translocation of B from root to shoot. Boron retranslocation was also studied as a mechanism of B efficiency.
44
Mugodo, James, e n/a. "Plant species rarity and data restriction influence the prediction success of species distribution models". University of Canberra. Resource, Environmental & Heritage Sciences, 2002. http://erl.canberra.edu.au./public/adt-AUC20050530.112801.
Testo completoAbstract (sommario):
There is a growing need for accurate distribution data for both common and rare plant
species for conservation planning and ecological research purposes. A database of more than
500 observations for nine tree species with different ecological and geographical
distributions and a range of frequencies of occurrence in south-eastern New South Wales
(Australia) was used to compare the predictive performance of logistic regression models,
generalised additive models (GAMs) and classification tree models (CTMs) using different
data restriction regimes and several model-building strategies. Environmental variables
(mean annual rainfall, mean summer rainfall, mean winter rainfall, mean annual temperature,
mean maximum summer temperature, mean minimum winter temperature, mean daily
radiation, mean daily summer radiation, mean daily June radiation, lithology and
topography) were used to model the distribution of each of the plant species in the study
area.
Model predictive performance was measured as the area under the curve of a receiver
operating characteristic (ROC) plot. The initial predictive performance of logistic regression
models and generalised additive models (GAMs) using unrestricted, temperature restricted,
major gradient restricted and climatic domain restricted data gave results that were contrary
to current practice in species distribution modelling. Although climatic domain restriction
has been used in other studies, it was found to produce models that had the lowest predictive
performance. The performance of domain restricted models was significantly (p = 0.007)
inferior to the performance of major gradient restricted models when the predictions of the
models were confined to the climatic domain of the species. Furthermore, the effect of data
restriction on model predictive performance was found to depend on the species as shown by
a significant interaction between species and data restriction treatment (p = 0.013). As found
in other studies however, the predictive performance of GAM was significantly (p = 0.003)
better than that of logistic regression. The superiority of GAM over logistic regression was
unaffected by different data restriction regimes and was not significantly different within
species.
The logistic regression models used in the initial performance comparisons were based on
models developed using the forward selection procedure in a rigorous-fitting model-building
framework that was designed to produce parsimonious models. The rigorous-fitting modelbuilding
framework involved testing for the significant reduction in model deviance (p =
0.05) and significance of the parameter estimates (p = 0.05). The size of the parameter
estimates and their standard errors were inspected because large estimates and/or standard
errors are an indication of model degradation from overfilling or effecls such as mullicollinearily.
For additional variables to be included in a model, they had to contribule
significantly (p = 0.025) to the model prediclive performance. An attempt to improve the
performance of species distribution models using logistic regression models in a rigorousfitting
model-building framework, the backward elimination procedure was employed for
model selection, bul it yielded models with reduced performance.
A liberal-filling model-building framework that used significant model deviance reduction at
p = 0.05 (low significance models) and 0.00001 (high significance models) levels as the
major criterion for variable selection was employed for the development of logistic
regression models using the forward selection and backward elimination procedures. Liberal
filling yielded models that had a significantly greater predictive performance than the
rigorous-fitting logistic regression models (p = 0.0006). The predictive performance of the
former models was comparable to that of GAM and classification tree models (CTMs). The
low significance liberal-filling models had a much larger number of variables than the high
significance liberal-fitting models, but with no significant increase in predictive
performance. To develop liberal-filling CTMs, the tree shrinking program in S-PLUS was
used to produce a number of trees of differenl sizes (subtrees) by optimally reducing the size
of a full CTM for a given species. The 10-fold cross-validated model deviance for the
subtrees was plotted against the size of the subtree as a means of selecting an appropriate
tree size. In contrast to liberal-fitting logistic regression, liberal-fitting CTMs had poor predictive performance.
Species geographical range and species prevalence within the study area were used to
categorise the tree species into different distributional forms. These were then used, to
compare the effect of plant species rarity on the predictive performance of logistic regression
models, GAMs and CTMs. The distributional forms included restricted and rare (RR)
species (Eucalyptus paliformis and Eucalyptus kybeanensis), restricted and common (RC)
species (Eucalyptus delegatensis, Eucryphia moorei and Eucalyptus fraxinoides),
widespread and rare (WR) species (Eucalyptus data) and widespread and common (WC)
species (Eucalyptus sieberi, Eucalyptus pauciflora and Eucalyptus fastigata). There were
significant differences (p = 0.076) in predictive performance among the distributional forms
for the logistic regression and GAM. The predictive performance for the WR distributional
form was significantly lower than the performance for the other plant species distributional
forms. The predictive performance for the RC and RR distributional forms was significantly
greater than the performance for the WC distributional form. The trend in model predictive
performance among plant species distributional forms was similar for CTMs except that the
CTMs had poor predictive performance for the RR distributional form.
This study shows the importance of data restriction to model predictive performance with
major gradient data restriction being recommended for consistently high performance. Given
the appropriate model selection strategy, logistic regression, GAM and CTM have similar
predictive performance. Logistic regression requires a high significance liberal-fitting
strategy to both maximise its predictive performance and to select a relatively small model
that could be useful for framing future ecological hypotheses about the distribution of
individual plant species. The results for the modelling of plant species for conservation
purposes were encouraging since logistic regression and GAM performed well for the
restricted and rare species, which are usually of greater conservation concern.
45
Chour, Zeinab. "Valorisation de terres rares à partir de plantes hyperaccumulatrices". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0142/document.
Testo completoAbstract (sommario):
En raison du risque d’un approvisionnement insuffisant en ressources primaires des terres rares et des impacts environnementaux générés par les zones minières, le concept de l’agromine paraît être une solution très prometteuse. Il permet d’extraire des métaux lourds à partir de sols pollués ou de friches industrielles, par une méthode respectueuse de l’environnement, grâce à la culture de plantes hyperaccumulatrices. Une fois la culture réalisée, des procédés hydrométallurgiques sont développés afin d’extraire des plantes les métaux ayant une valeur économique importante. Le présent travail vise à développer des procédés hydrométallurgiques pour l’extraction des terres rares à partir d’une plante hyperaccumulatrice appelée Dicranopteris dichotoma. Cette fougère est connue pour sa capacité à accumuler les terres rares, notamment les légères, dans sa partie aérienne. Différentes voies d’extraction, puis de séparation des terres rares des autres éléments, ont été étudiées. Dans un premier temps, des lixiviations de la biomasse sèche ont été mises en oeuvre. Les rendements de lixiviation selon la nature de l’extractant ont ainsi pu être comparés. Pour cette voie, une précipitation est ensuite effectuée, suivie d’une calcination pour obtenir les oxydes de terres rares. Dans un second temps, la lixiviation de la biomasse sèche a été intensifiée par un procédé d’échange d’ions au cours duquel les terres rares sont fixées sur la résine. Après avoir percolé sur la résine des solutions qui permettent d’éliminer des impuretés, l’élution permet d’obtenir une solution concentrée de terres rares. Enfin, une troisième voie d’extraction est réalisée à partir des cendres de D. dichotoma, après une étape de combustion. Cette voie repose sur une lixiviation alcaline des cendres permettant l’élimination des impuretés solubles dans ce milieu. Une dissolution du résidu est ensuite effectuée, suivie d’une précipitation sélective des terres rares. Les trois voies étudiées s’avèrent en fait complémentaires et la combinaison de certaines étapes peut s’avérer prometteuse, notamment pour éliminer certaines impuretés. L’étude de ces procédés et de leur combinaison mérite d’être poursuivie afin d’améliorer les rendements d’extraction et la pureté du produit final. Il s’agira ensuite de développer un procédé à l’échelle pilote puis industrielleDue to the risk of primary resource supply of rare earths and the environmental impacts generated by mining areas, the concept of agromining seems to be a very promising solution. It allows the extraction of heavy metals from polluted soils or industrial wastelands, by an environmentally friendly method, thanks to the cultivation of hyperaccumulating plants. Once the culture is completed, hydrometallurgical processes are developed in order to extract from plants the metals having a significant economic value. The present work aims to develop hydrometallurgical processes for the extraction of rare earths from a hyperaccumulator plant called Dicranopteris dichotoma. This fern is known for its high ability to accumulate rare earths, especially light ones, in its aerial part. Different extraction and separation ways of rare earths from other elements have been studied. At first, leaching of dry biomass was implemented. The leaching yields according to the nature of extracting solutions could thus be compared. For this approach, precipitation is then performed, followed by calcination step to obtain rare earth oxides. In a second approach, the leaching of dry biomass was intensified by an ion exchange process during which, the rare earths are fixed on the resin. After percolating solutions on the resin in order to eliminate impurities, an elution step leads to obtain a concentrated solution of rare earths. Finally, a third extraction process is carried out from the ashes of D. dichotoma, after a combustion step. This approach is based on an alkaline leaching of the ash allowing the elimination of soluble impurities in this medium. The residue is then dissolved, followed by rare earths selective precipitation. These three approaches studied, are actually complementary and the combination of certain steps can be promising, especially to eliminate some impurities. The study of these processes and their combination deserves to be pursued in order to improve the extraction yields and the purity of final product. It will then develop a pilot scale and industrial process
46
Mulyati. "Zinc requirements of transplanted oilseed rape". Thesis, Mulyati, (2004) Zinc requirements of transplanted oilseed rape. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/213/.
Testo completoAbstract (sommario):
Transplanting is a common practice for many horticultural crops and some field crops. Recently, transplanted oilseed rape (Brassica napus L.) crops have been reported to be sensitive to zinc (Zn) deficiency. However, Zn nutrition in transplanted field crops has not been investigated in detail. The objectives of this present research were to investigate whether transplanting increases external Zn requirements of transplanted oilseed rape, and the mechanisms of root function, growth and Zn uptake after transplanting including rhizosphere modification capacity by plant roots. The second objective was to examine the relative effects of root pruning and transplanting on Zn responses of oilseed rape, and the third objective was to determine external and internal Zn requirements of transplanted oilseed rape for diagnosing and predicting Zn deficiency.
An experiment on a low Zn sand (DTPA extractable Zn 0.14 mg kg-1) was set up to determine whether transplanted oilseed rape had a higher Zn requirement than that of direct-sown plants. Low Zn supply depressed shoot dry weight, however, root growth was relatively more strongly suppressed than shoots. Maximum root dry weight required much higher external Zn for transplanted plants compared to direct-sown plants, whilst shoot dry weight required a similarly low external Zn supply. In addition, transplanted plants were sensitive to zinc deficiency during the early post-transplanting growth, and the response weakened as the plants recovered from root injury or transplanting stress. However, the transplanted plants also experienced root pruning before transplanting and so in this experiment the higher Zn requirement could have been due to root pruning or transplanting or both.
A further experiment was undertaken to determine the comparative external Zn requirements of direct-sown and transplanted plants in well-stirred chelate-buffered solution culture where a rhizosphere effect on plant availability of Zn forms is absent and the effects of poor root-soil contact on post-transplanting growth are minimized. In solution culture at the same level of Zn supplied, direct- sown plants produced higher shoot and root dry matter and greater root length than those of transplanted plants. However, since a higher external Zn requirement was found for transplanted plants in buffered solution culture than for direct- sown plants, it was concluded that the higher Zn requirement was not related to decreased rhizosphere modification, to greater demand for Zn or to poor root-solution contact, but rather to the time required for transplanted plants to recover from transplanting and root injury. The recovery of root function in solution culture was more rapid than that in soil culture and expressed as a higher Zn requirement for shoot as well as root growth. It suggested that the delay in root recovery in soil culture was due to slower absorption of Zn from the soil after transplanting than was the case in solution culture.
Chelate-buffered nutrient solution culture and harvesting plants successively at 5 day intervals until 25 days after transplanting was used to examine the mechanisms of the recovery of root growth and function. In this experiment, the external Zn requirement of transplanted plants was investigated with unpruned or pruned root systems. Plants with unpruned root system and sufficient Zn supply exhibited faster recovery from transplanting than those with pruned root system plants. The results suggest that root pruning impaired Zn uptake by plant roots and slowed down the root and shoot growth after transplanting. Increased solution Zn partly alleviated the effects of root pruning and presumably this is a major reason why transplanted oilseed rape had a high external Zn requirement. However, root pruning also appeared to impair water uptake, and may have suppressed shoot growth through sequestering carbon for new root growth and through decreased phytohormone production by roots.
Since rapid root recovery of transplanted plants is essential for successful of growth in the field, Zn application to the nursery bed was explored as a starter fertilizer to stimulate root growth after transplanting. The objective of this experiment was to determine whether increasing the seedbed Zn would stimulate new root growth of transplanted oilseed rape, and therefore would alleviate the need for increased external Zn for post-transplanting growth. Results showed that adequate Zn concentration in the seedbed promoted the post-transplanting growth by stimulating the new root growth especially increased root length, and also hastened the recovery of root systems. However, high Zn concentration at transplanting still had a more dominant effect in stimulating the new root growth of oilseed rape after transplanting.
The final experiment was set up using rhizobags with three rates of Zn supply and unpruned or pruned root systems. The purpose of this study was to investigate the chemical change in the rhizosphere and non-rhizosphere or bulk soil and its relationship to the recovery of root function after transplanting, and also to identify and quantify the organic acids in soil extracts of direct-sown and transplanted plants. The rhizosphere soil pH was lower than that of non-rhizosphere soil, and the decrease of soil pH was suggested as the mechanism of the increase of Zn availability and mobility in the rhizosphere soil. Direct-sown plants were more efficient in utilizing Zn than those of transplanted plants especially compared to those of plants with pruned root system. Zinc deficient plants excreted higher concentration of organic acids particularly citric acid, suggesting this was a mechanism of Zn mobilization and Zn uptake by roots of oilseed rape.
The main implications of the present study for the management of Zn nutrition of transplanted crops were: the need to increase the Zn application to crops in the nursery and at transplanting compared to direct-sown plants; the possibility that external requirements of other nutrients will be greater in transplanted crops also requires further consideration; and in cropping systems where transplanting is practised, greater attention should be given to the avoidance of root damage during the transplanting.
47
Mulyati. "Zinc requirements of transplanted oilseed rape". Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060109.135933.
Testo completoAbstract (sommario):
Transplanting is a common practice for many horticultural crops and some field crops. Recently, transplanted oilseed rape (Brassica napus L.) crops have been reported to be sensitive to zinc (Zn) deficiency. However, Zn nutrition in transplanted field crops has not been investigated in detail. The objectives of this present research were to investigate whether transplanting increases external Zn requirements of transplanted oilseed rape, and the mechanisms of root function, growth and Zn uptake after transplanting including rhizosphere modification capacity by plant roots. The second objective was to examine the relative effects of root pruning and transplanting on Zn responses of oilseed rape, and the third objective was to determine external and internal Zn requirements of transplanted oilseed rape for diagnosing and predicting Zn deficiency.
An experiment on a low Zn sand (DTPA extractable Zn 0.14 mg kg-1) was set up to determine whether transplanted oilseed rape had a higher Zn requirement than that of direct-sown plants. Low Zn supply depressed shoot dry weight, however, root growth was relatively more strongly suppressed than shoots. Maximum root dry weight required much higher external Zn for transplanted plants compared to direct-sown plants, whilst shoot dry weight required a similarly low external Zn supply. In addition, transplanted plants were sensitive to zinc deficiency during the early post-transplanting growth, and the response weakened as the plants recovered from root injury or transplanting stress. However, the transplanted plants also experienced root pruning before transplanting and so in this experiment the higher Zn requirement could have been due to root pruning or transplanting or both.
A further experiment was undertaken to determine the comparative external Zn requirements of direct-sown and transplanted plants in well-stirred chelate-buffered solution culture where a rhizosphere effect on plant availability of Zn forms is absent and the effects of poor root-soil contact on post-transplanting growth are minimized. In solution culture at the same level of Zn supplied, direct- sown plants produced higher shoot and root dry matter and greater root length than those of transplanted plants. However, since a higher external Zn requirement was found for transplanted plants in buffered solution culture than for direct- sown plants, it was concluded that the higher Zn requirement was not related to decreased rhizosphere modification, to greater demand for Zn or to poor root-solution contact, but rather to the time required for transplanted plants to recover from transplanting and root injury. The recovery of root function in solution culture was more rapid than that in soil culture and expressed as a higher Zn requirement for shoot as well as root growth. It suggested that the delay in root recovery in soil culture was due to slower absorption of Zn from the soil after transplanting than was the case in solution culture.
Chelate-buffered nutrient solution culture and harvesting plants successively at 5 day intervals until 25 days after transplanting was used to examine the mechanisms of the recovery of root growth and function. In this experiment, the external Zn requirement of transplanted plants was investigated with unpruned or pruned root systems. Plants with unpruned root system and sufficient Zn supply exhibited faster recovery from transplanting than those with pruned root system plants. The results suggest that root pruning impaired Zn uptake by plant roots and slowed down the root and shoot growth after transplanting. Increased solution Zn partly alleviated the effects of root pruning and presumably this is a major reason why transplanted oilseed rape had a high external Zn requirement. However, root pruning also appeared to impair water uptake, and may have suppressed shoot growth through sequestering carbon for new root growth and through decreased phytohormone production by roots.
Since rapid root recovery of transplanted plants is essential for successful of growth in the field, Zn application to the nursery bed was explored as a starter fertilizer to stimulate root growth after transplanting. The objective of this experiment was to determine whether increasing the seedbed Zn would stimulate new root growth of transplanted oilseed rape, and therefore would alleviate the need for increased external Zn for post-transplanting growth. Results showed that adequate Zn concentration in the seedbed promoted the post-transplanting growth by stimulating the new root growth especially increased root length, and also hastened the recovery of root systems. However, high Zn concentration at transplanting still had a more dominant effect in stimulating the new root growth of oilseed rape after transplanting.
The final experiment was set up using rhizobags with three rates of Zn supply and unpruned or pruned root systems. The purpose of this study was to investigate the chemical change in the rhizosphere and non-rhizosphere or bulk soil and its relationship to the recovery of root function after transplanting, and also to identify and quantify the organic acids in soil extracts of direct-sown and transplanted plants. The rhizosphere soil pH was lower than that of non-rhizosphere soil, and the decrease of soil pH was suggested as the mechanism of the increase of Zn availability and mobility in the rhizosphere soil. Direct-sown plants were more efficient in utilizing Zn than those of transplanted plants especially compared to those of plants with pruned root system. Zinc deficient plants excreted higher concentration of organic acids particularly citric acid, suggesting this was a mechanism of Zn mobilization and Zn uptake by roots of oilseed rape.
The main implications of the present study for the management of Zn nutrition of transplanted crops were: the need to increase the Zn application to crops in the nursery and at transplanting compared to direct-sown plants; the possibility that external requirements of other nutrients will be greater in transplanted crops also requires further consideration; and in cropping systems where transplanting is practised, greater attention should be given to the avoidance of root damage during the transplanting.
48
Chour, Zeinab. "Valorisation de terres rares à partir de plantes hyperaccumulatrices". Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0142.
Testo completoAbstract (sommario):
En raison du risque d’un approvisionnement insuffisant en ressources primaires des terres rares et des impacts environnementaux générés par les zones minières, le concept de l’agromine paraît être une solution très prometteuse. Il permet d’extraire des métaux lourds à partir de sols pollués ou de friches industrielles, par une méthode respectueuse de l’environnement, grâce à la culture de plantes hyperaccumulatrices. Une fois la culture réalisée, des procédés hydrométallurgiques sont développés afin d’extraire des plantes les métaux ayant une valeur économique importante. Le présent travail vise à développer des procédés hydrométallurgiques pour l’extraction des terres rares à partir d’une plante hyperaccumulatrice appelée Dicranopteris dichotoma. Cette fougère est connue pour sa capacité à accumuler les terres rares, notamment les légères, dans sa partie aérienne. Différentes voies d’extraction, puis de séparation des terres rares des autres éléments, ont été étudiées. Dans un premier temps, des lixiviations de la biomasse sèche ont été mises en oeuvre. Les rendements de lixiviation selon la nature de l’extractant ont ainsi pu être comparés. Pour cette voie, une précipitation est ensuite effectuée, suivie d’une calcination pour obtenir les oxydes de terres rares. Dans un second temps, la lixiviation de la biomasse sèche a été intensifiée par un procédé d’échange d’ions au cours duquel les terres rares sont fixées sur la résine. Après avoir percolé sur la résine des solutions qui permettent d’éliminer des impuretés, l’élution permet d’obtenir une solution concentrée de terres rares. Enfin, une troisième voie d’extraction est réalisée à partir des cendres de D. dichotoma, après une étape de combustion. Cette voie repose sur une lixiviation alcaline des cendres permettant l’élimination des impuretés solubles dans ce milieu. Une dissolution du résidu est ensuite effectuée, suivie d’une précipitation sélective des terres rares. Les trois voies étudiées s’avèrent en fait complémentaires et la combinaison de certaines étapes peut s’avérer prometteuse, notamment pour éliminer certaines impuretés. L’étude de ces procédés et de leur combinaison mérite d’être poursuivie afin d’améliorer les rendements d’extraction et la pureté du produit final. Il s’agira ensuite de développer un procédé à l’échelle pilote puis industrielleDue to the risk of primary resource supply of rare earths and the environmental impacts generated by mining areas, the concept of agromining seems to be a very promising solution. It allows the extraction of heavy metals from polluted soils or industrial wastelands, by an environmentally friendly method, thanks to the cultivation of hyperaccumulating plants. Once the culture is completed, hydrometallurgical processes are developed in order to extract from plants the metals having a significant economic value. The present work aims to develop hydrometallurgical processes for the extraction of rare earths from a hyperaccumulator plant called Dicranopteris dichotoma. This fern is known for its high ability to accumulate rare earths, especially light ones, in its aerial part. Different extraction and separation ways of rare earths from other elements have been studied. At first, leaching of dry biomass was implemented. The leaching yields according to the nature of extracting solutions could thus be compared. For this approach, precipitation is then performed, followed by calcination step to obtain rare earth oxides. In a second approach, the leaching of dry biomass was intensified by an ion exchange process during which, the rare earths are fixed on the resin. After percolating solutions on the resin in order to eliminate impurities, an elution step leads to obtain a concentrated solution of rare earths. Finally, a third extraction process is carried out from the ashes of D. dichotoma, after a combustion step. This approach is based on an alkaline leaching of the ash allowing the elimination of soluble impurities in this medium. The residue is then dissolved, followed by rare earths selective precipitation. These three approaches studied, are actually complementary and the combination of certain steps can be promising, especially to eliminate some impurities. The study of these processes and their combination deserves to be pursued in order to improve the extraction yields and the purity of final product. It will then develop a pilot scale and industrial process
49
Fearon, Joclyn Joe. "Population assessments of priority plant species used by local communities in and around three Wild Coast reserves, Eastern Cape, South Africa". Thesis, Rhodes University, 2011. http://hdl.handle.net/10962/d1007059.
Testo completoAbstract (sommario):
The project was initiated by Eastern Cape Parks (ECP) as a request for the construction of inventories of priority species and their population levels inside three nature reserves on the Eastern Cape Wild Coast, South Africa, and to develop a strategic management plan to manage these natural resources in each reserve. Thirty key species were identified by local communities in and around Dwesa-Cwebe, Silaka and Mkambati Nature Reserves through community workshops. For forested areas belt transects of 100 m x 6 m where used. The basal circumference of key tree species within the belt transect was measured as well as the height of saplings (height < 150 m). Tree species were categorized based on densities, size class distribution (SCD) curves and values, and spatial grain. For grassland areas straight transects of 200 m long were used, along which ten 3 m x 3 m quadrates were placed at 20 m intervals. Within each grassland transect the height of herbs or tuft diameter of grasses was recorded and percentage cover estimated. Grassland species were categorized based on density, SCD curves and percentage cover. All species were placed into harvesting categories based on analysed ecological data that was collected in the field. Category 1 species were very rare or not found in the reserve and it was recommended that species be conserved and monitored. Category 2 species had low densities in the reserve indicating declining populations and was suggested that these be monitored and not harvested. Category 3 species had high densities and have potential for harvesting with strict limitations. Category 4 species were most abundant with very high densities and can be harvested within management guidelines. These categories were grouped further using social and ecological data such as harvesting risk, frequency of collection, use value and number of uses. This highlighted which species have conservation priority within each category and a decision can be made as to how intense or limited extraction should be. By incorporating GIS the distribution of each species was looked at and harvesting and non-harvesting zones established to determine where species can be extracted. Monitoring plans must consider the quantity of plant material collected, fire regimes, optimal harvesting rates and harvesting zones, and be able to pick up changes in populations. Also, it is important that the community be involved in conserving and monitoring these species. Adaptive monitoring and management must be used to steer harvesting practices in the Wild Coast reserves. This allows for the development of harvesting practices through ‘learning by doing’, and the evolution of good questions to guide monitoring decisions
50
Geißler, Katja. "Lebensstrategien seltener Stromtalpflanzen : autökologische Untersuchung von Cnidium dubium, Gratiola officinalis und Juncus atratus unter besonderer Berücksichtigung ihrer Stressresistenz". Phd thesis, Universität Potsdam, 2008. http://opus.kobv.de/ubp/volltexte/2008/1746/.
Testo completoAbstract (sommario):
Die vorliegende Dissertation behandelt die Ökologie von Cnidium dubium (Schkuhr) Thell. (Sumpf-Brenndolde), Gratiola officinalis L. (Gottes-Gnadenkraut) und Juncus atratus Krocker (Schwarze Binse), drei gefährdeten Arten, die als sogenannte Stromtalpflanzen in Mitteleuropa in ihrem Vorkommen eng an die Flussauen gebunden sind.
Die Arbeit basiert auf verschiedenen Simulationsexperimenten und Feldstudien in der Unteren Havelniederung, einem „Feuchtgebiet von internationaler Bedeutung“. Sie behandelt Themenkomplexe wie das Samenbankverhalten, die Samenkeimung, die Stickstofflimitierung, die Konkurrenzkraft, das Verhalten der Pflanzen nach einer Sommertrockenheit und nach einer Winter/Frühjahrsüberflutung. Ferner widmet sie sich der Populationsbiologie der Arten und dem Verhalten der Pflanzen nach besonderen Störungsereignissen wie Mahd, Herbivorie und der Sommerflut 2002.
Der Leser erfährt, wie die Pflanzen in verschiedenen Lebensphasen auf die auentypische Umwelt reagieren und erhält umfassende Einblicke in physiologische Mechanismen, die der Anpassung an die typischen Bedingungen einer mitteleuropäischen Flussaue dienen.
Eine Interpretation der Ergebnisse zeigt auf, welche der spezifischen Eigenschaften zur Gefährdung der drei Stromtalarten beitragen.
Die Arbeit ist für den Arten-, Biotop- und Landschaftsschutz interessant. Darüber hinaus bietet sie zahlreiche Anknüpfungspunkte zur ökophysiologischen Grundlagenforschung. Die verstärkte Nutzung physiologischer Methoden bei der Klärung ökologischer Fragestellungen wird angeregt.The thesis deals with the ecology of three endangered European river corridor angiosperms Cnidium dubium (Schkuhr) Thell., Gratiola officinalis L. und Juncus atratus Krocker. The study is based on different experimental approaches and field surveys in a wetland along the Lower Havel River, a designated German Ramsar-site (Wetland of International Importance). This involves the examination of aspects of seed bank dynamics, germination, nitrogen limitation, competitive ability, and the response of plants to summer drought and/or winter/spring flooding. The thesis continues with a detailed study of the population biology of the species at natural sites and the response of these plants to specific disturbances like mowing, herbivory and the severe summer flooding in 2002. The reader learns about the traits of the three plant species to tolerate the typical conditions their natural sites are exposed to in different phases of their life cycle. He gets a comprehensive look at physiological means by which plants can adapt to the prevailing conditions of European river lowlands. The interpretation of the results is used to reveal specific plant traits, which may contribute to the endangerment of the three river corridor plants. As such, this thesis is interesting for protection of species, biotopes and landscapes. Furthermore, it provides numerous close connections to fundamental research from an ecophysiological perspective. The increased use of physiological methods is recommended in order to be able to adequately resolve ecological problems.