Tesi: "Orchid conservation"

1

Wraith, Jenna L. "Orchid conservation: Assessing threats and conservation priorities." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/392403.

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Globally, over a million species are threatened with extinction from habitat loss, climate change, over-exploitation as well as other anthropogenic activities. Orchids are particularly at risk in part due to their distinctive ecology including high species diversity, often limited geographic range for many species, and tight ecological relations with specific symbionts. They are the most diverse group of flowering plants with ~28,000 species and are found on all but one continent. However, due to increasing pressures from humans many orchids are threatened with extinction. It is therefore important to assess what is threatening them and where. Therefore, this thesis assesses threats to orchids at a global and continental scale to highlight the most significant threats to orchids, where orchids are threatened and by what, and to prioritise conservation actions and future research. The range and diversity of threats to orchids was globally assessed and mapped using data from the International Union for Conservation of Nature (IUCN) Red List (Chapter 2). For the 442 orchids on the Red List, the most common threats were biological resource use (80% species), agriculture (53%), human intrusion and disturbance (36%) and development (35%) and were most commonly found in Africa (predominantly Madagascar), South and East Asia and South America. These threats often interacted and co-occurred with four major threat syndromes. Understanding threat syndromes is vital for orchid conservation as they can create more consistent conservation planning and help focus efforts on the specific threats in a given region. Globally the scale and extent of tourism and recreation is increasing, including nature-based tourism. As a result, tourism and recreation is increasingly recognised as a threat to plants including orchids. Therefore, the extent and nature of tourism and recreation as a threat to orchids globally was also assessed in more detail using data from the IUCN Red List (Chapter 3). This demonstrated that 149 of the 442 listed orchids were threatened by tourism and recreation including impacts of residential and commercial development for tourism infrastructure (22%), intentional collecting within protected areas (17%), and human intrusion and disturbance from recreational activities (20%). Tourism and recreation threats were severe, impacting many populations of some orchids and causing rapid decline. These findings highlight how tourism and recreation can threaten specific groups of plants in diverse habitats, but particularly in forests and shrublands and these threats often co-occurred as threat syndromes. To better facilitate orchid conservation, a more detailed analysis of geographical patterns in threatened orchids and threats to orchids was conducted at a continental scale using a methodology that could be adapted to other threatened taxa (Chapter 4). By utilising data on threatened orchids from the Australian Government, combined with species occurrence data from the Atlas of Living Australia, the distribution of the most severe threats to orchids in Australia were mapped. This included identifying locations where habitat modification, changing fire regimes, grazing, weeds, tourism and recreation and illegal collection occurred, including where they co-occurred as threat syndromes. This study shows that the loss of native vegetation is a key driver of most threats, while increases within protected areas was associated with an increased threat from tourism and recreation. This study also provides critical information for formulating conservation and management strategies for threatened orchids and other species in a changing environment. To ensure the successful conservation of orchids, researchers need to understand research and conservation priorities at a global scale. Therefore, conservation and research priorities for orchid conservation were assessed (Chapter 5) using data on research publications on orchid conservation from Scopus, data on conservation priorities from the Red List, and species occurrence records from the Global Biodiversity Information Facility (GBIF). This study highlighted the increase in conservation research and important gaps as well as key conservation priorities which were analysed to guide recommendations on future priorities. Based on the results, orchid conservation and research globally should increasingly focus on monitoring population, trends and distributions including the impacts of climate change, ecology, threats and threat mitigation, protection and management of species and their habitats and increasing education and awareness. The research in this thesis demonstrated how orchids are significantly threatened by anthropogenic activities at a global and continental scale including impacts from habitat loss, illegal collecting, tourism and recreation, increased fire regimes and invasive species. However, it is also evident that climate change is underrepresented as a threat to orchids and needs to be considered in future research. These studies highlight the prevalence and importance of threat syndromes and provide novel methods for spatially assessing them. It is evident from these studies that orchid conservation will benefit from global collaboration and focussed conservation priorities. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) School of Environment and Sc Science, Environment, Engineering and Technology Full Text

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2

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.

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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.

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3

Slaviero, Antonio <1986&gt. "Ecology and conservation strategies of target dry grassland orchid species (Orchidaceae)." Doctoral thesis, Università Ca' Foscari Venezia, 2015. http://hdl.handle.net/10579/8345.

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A causa del loro elevato livello di specializzazione ecologica, le Orchidaceae sono specie altamente vulnerabili e minacciate a scala globale ma anche bioindicatori dello stato degli habitat in cui vivono. Al fine di salvaguardare la biodiversità si rende necessario un approccio conservativo basato sulla conoscenza dell’ecologia delle specie, degli habitat in cui vivono e dei rapporti con altri organismi. Questa tesi considera tre orchidee (A. morio; H. adriaticum, O. sphegodes) quali target di studio per comprendere quali fattori ecologici siano i driver della loro fitness in un habitat particolarmente ricco di specie ma anche minacciato a livello europeo, la prateria arida semi-naturale su substrato calcareo. Vengono analizzati la struttura della vegetazione, i rapporti con i pronubi, la topografia locale e l’ambiente edafico, ottenendo interessanti pattern rispetto alla copertura e fitness riproduttiva delle specie target. Un approfondimento è dedicato ai processi di germinazione evidenziando l’utilità dell’impollinazione artificiale per superare l’imbreeding e testando un nuovo metodo di scarificazione enzimatica.

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4

Stewart, Scott L. "Integrated conservation of Florida Orchidaceae in the genera Habenaria and Spiranthes : model orchid conservation systems for the Americas /." View online, 2007. http://etd.fcla.edu/UF/UFE0021367/stewart_s.pdf.

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5

Mursidawati, Sofi. "Mycorrhizal association, propagation and conservation of the myco-heterotrophic orchid Rhizanthella gardneri." University of Western Australia. School of Earth and Geographical Sciences, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0014.

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Many orchids require mycorrhizal symbioses with fungi for their development and survival. Rhizanthella gardneri the Western Australian underground orchid is associated with the companion plant Melaleuca uncinata and its ectomycorrhizal fungus symbiont. Much less is known about the habitat requirements of its sister species, R. slateri, which occurs in Eastern Australia. The absence of chlorophyll from Rhizanthella gardneri and R. slateri results in total dependency on associations with fungal symbionts. Many ecological and biological aspects of these fascinating orchids remained poorly known, including the identity of the fungal associates and the nature of their tripartite associations with Rhizanthella and Melaleuca. Extremely high specificity of these mycorrhizal relationships is likely to be the most important factor explaining the highly specific habitat requirements of underground orchids. The purpose of this study was to conduct further investigations of the role of the mycorrhizal associations of Australian underground orchids by identifying the fungi involved in these associations, optimising their growth in sterile culture and devising efficient means for synthesising their tripartite associations with R. gardneri and M. uncinata. In total, 16 isolates of fungi were successfully obtained from the two underground orchids and used in a series of experiments to understand both the nature of the fungi and their relationship with orchids. The identity of these fungi was established by using conventional morphological and molecular methods. Cultural and morphological studies revealed that all isolates from R. gardneri and R. slateri were binucleate rhizoctonias with affinities to members of the genus Ceratobasidium. However, the teleomorph state that was observed from the R. slateri symbiont during this study more closely resembled a Thanatephorus species. Further identification using ITS sequence comparisons confirmed that mycorrhizal fungi of Rhizanthella belonged to the Rhizoctonia alliance with relatives that include Thanatephorus, Ceratobasidium, or Rhizoctonia from other continents with over 90% similarity. Most of these related fungi are known as plant pathogens, but some were orchid mycorrhizal fungi. However, the isolates from the two underground orchids were most closely related to each other and formed a discrete group relative to other known members of the Rhizoctonia alliance. Sterile culture experiments determined culture media preferences for mycorrhizal fungi from Rhizanthella and other orchids. A fully defined sterile culture medium designed to more closely resemble Australian soil conditions was formulated. This new medium was compared to undefined media containing oats or yeast extract and recommendations for growth of these fungi are provided. The undefined media based on oats provided the best growth of most fungi, but the new Australian soil media was also effective at growing most orchid mycorrhizal fungi and this fully defined media was less prone to contamination and should provide more reproducible results. A comparison of three methods for inoculating M. uncinata with the underground orchid fungi resulted in the production and characterisation of ectomycorrhizal roots and hyphae formed by fungi isolated from R. gardneri and R. slateri. These underground orchid fungi could easily be distinguished from other mycorrhizal fungi (caused by airborne contamination) by the characteristic appearance of these roots and hyphae. A new system for growing and observing tripartite mycorrhizal associations was devised using pots with side viewing windows and the use of transparent seed packets to contain Rhizanthella seeds. This method allowed all the stages of seed germination to be observed in the glasshouse, culminating in the production of underground orchid rhizomes. Seed germination was only successful when seed was placed directly over active M. uncinata ectomycorrhizas confirmed to belong to the correct fungus by microscopic observations through the side of window pots. The importance of these new scientific discoveries concerning the biology and ecology of the underground orchids and their associated fungi for the recovery of these critically endangered orchids are discussed.

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6

Gale, Stephan William. "Population ecology and conservation of Nervilia nipponica, an endangered orchid in Japan." Thesis, University of Sussex, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494944.

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Nervilia nipiponica is a small terrestrial orchid known from a limited number of woodland sites in southwest and central Japan. Its scattered distribution, small total population size and sensitivity to stochastic events have led to its classification as Endangered at the national level, and it has recently been selected as a priority species for conservation. However, the reasons for the species' rarity are obscure, and the means by which its endangered status might be ameliorated remain speculative. In this study, multi-disciplinary research was undertaken to illuminate details of the species' ecology towards the development of practical management guidelines.

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7

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.

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8

Gustafsson, Susanne. "Population genetic analyses in the orchid genus Gymnadenia : a conservation genetic perspective." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3305.

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9

Sharma, Jyotsna. "Mycobionts, germination, and conservation genetics of federally threatened Platanthera praeclara (Orchidaceae) /." free to MU campus, to others for purchase, 2002. http://wwwlib.umi.com/cr/mo/fullcit?p3060142.

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10

Bougoure, Jeremy J. "The role of mycorrhizal fungi in nutrient supply and habitat specificity of the rare mycoheterotrophic underground orchid, Rhizanthella gardneri." University of Western Australia. School of Plant Biology, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0076.

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Rhizanthella gardneri (Rogers) is a critically endangered orchid restricted to two isolated regions of south-western Australia. Rhizanthella gardneri is an entirely subterranean mycoheterotrophic species that purportedly forms a tripartite relationship with a mycorrhizal fungus (Ceratobasidiales) that links with an autotrophic shrub of the Melaleuca uncinata complex to acquire nutrients. Whether the rarity of R. gardneri is intrinsic is overshadowed by the recent effect of extrinsic factors that means R. gardneri requires some form of conservation and may also be a viable candidate for restoration. To create an integrated conservation strategy for R. gardneri, reasons for its decline and knowledge of its biological and ecological functioning must be elucidated. This thesis focuses on three key questions; 1) what are the habitat requirements and limitations to R. gardneri survival; 2) what is the identity and specificity of the fungus R. gardneri forms mycorrhizas with; and 3) does R. gardneri form a nutrient-sharing tripartite relationship with a mycorrhizal fungus and autotrophic shrub. Key climate, soil and vegetation characteristics of known R. gardneri habitats were quantified to provide baseline data for monitoring known R. gardneri populations, to better understand how R. gardneri interacts with its habitat, and to identify possible new sites for R. gardneri introduction. Habitats of the two known R. gardneri populations differed considerably in soil chemistry, Melaleuca structure and Melaleuca productivity. Individual sites within populations were relatively similar in all attributes measured while overall Northern and Southern habitats were distinct from each other. These results suggest that R. gardneri can tolerate a range of conditions and may be more widespread than previously thought, given that there are extensive areas of Melaleuca thickets with similar habitat characteristics across south-western Australia. The fungus forming mycorrhizas with R. gardneri was identified, using nuclear ribosomal DNA sequences, as a Rhizoctonia-type fungus within the Ceratobasidiales. All fungi isolated from R. gardneri individuals representative of its currently known distribution were genetically similar, suggesting R. gardneri is highly dependent on this specific fungal species. Given that R. gardneri appears to exclusively associate with a specific fungal species, species-specific molecular primers were designed and used to analyse the fungis presence in known and potential R. gardneri habitats. These results 6 suggest that the fungus exists beyond the known R. gardneri habitats and gives hope to finding new populations.

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11

Lin, Wuying. "Comparative Reproductive Biology of a Rare Endemic Orchid and its Sympatric Congeners in Southwestern China." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/570.

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Comparative studies on endangered species and their more common congeners can shed light on the mechanism of species rarity, and enable conservationists to formulate effective management strategies. I compared the breeding and pollination systems of the endangered Geodorum eulophioides and its two more common sympatric congeners in subtropical China. Geodorum eulophioides and G. recurvum were self-compatible, both depending on Ceratina cognata for fruit production, while G. densiflorum can autonomously self. Although the floral visitation frequency of G. eulophioides was the highest among the three, its natural fruit set was similar to that of G. recurvum, but both lower than that of G. densiflorum. These results partially explain the difference in species abundance. Coupled with severe habitat loss and degradation, the extremely low pollinator visitation and natural fruit set of G. eulophioides calls for rapid establishment of ex-situ collection, in conjunction with improving in-situ habitat. Natural hybridization tendencies were also studied among species.

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12

Sanborn, Mark A. "A Model for Field Deployment of Wireless Sensor Networks (WSNs) within the Domain of Microclimate Habitat Monitoring." NSUWorks, 2011. http://nsuworks.nova.edu/gscis_etd/296.

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Wireless sensor networks (WSNs) represent a class of miniaturized information systems designed to monitor physical environments. These smart monitoring systems form collaborative networks utilizing autonomous sensing, data-collection, and processing to provide real-time analytics of observed environments. As a fundamental research area in pervasive computing and envisioned as large-scale autonomous networks of communicating nodes capable of monitoring conditional metrics over vast geographic areas, WSNs have the potential to provide researchers and conservationists with increased knowledge of the intricacies and interrelationships of disparate environments. The author addressed the problem of developing a methodology for the design and deployment of WSNs in uncontrolled and harsh outdoor environments. Within the context of a research and conservation field study of flora, the author developed a model for deployment of WSNs within the domain of microclimate habitat monitoring. The goal of this study was to contribute to the body of knowledge in WSN research by developing a model for deployment that was scientifically sound and replicable. To accomplish this goal, the author conducted an investigation of current technologies associated with WSNs, their capabilities, and their applications specific to the stated domain. To validate this model, the author deployed a WSN for monitoring the microclimate habitats of a population of Spiranthes lacera var. gracilis, common name, slender ladies' tresses. During this field study, the WSN performed according to design and produced sufficient data to provide an accurate representation of the microclimate habitats of the objects of study. As a contribution to the WSN research body of knowledge, the author used an SDLC methodology to provide a pragmatic approach to deployment focused on the elements of nuance specific to WSNs for microclimate habitat monitoring.

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13

Borey, Erica. "Reichenbachia, Imperial Edition: Rediscovering Frederick Sander’s Late-Victorian Masterpiece of Botanical Art." VCU Scholars Compass, 2013. http://scholarscompass.vcu.edu/etd/3292.

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This thesis project examines the history, provenance, and contemporary treatment of a rare Imperial Edition of Frederick Sander’s print collection Reichenbachia, Orchids Illustrated and Described, a high-quality orchid compendium dating to the late-nineteenth century. A local philanthropist loaned the Imperial Edition Reichenbachia, number 86 of 100 to Lewis Ginter Botanical Garden in 2011 on a long-term basis as a promised donation. Research into the origins of this collection involves several disparate historical topics, including the Victorian period of “orchid mania,” imperialist business practices, and chromolithographic printmaking. Discussion of the transition of this collection into a museum art collection covers its consequent registration, conservation, and exhibition. Finally, this thesis project considers the advantages and disadvantages of managing an art collection at a botanical garden.

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Tsui, Yuk-chun Prisca. "Conservation and propagation of wild orchids in Hong Kong /." [Hong Kong : University of Hong Kong], 1992. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13226290.

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Yam, Tim-wing. "Conservation, ecology and propagation of the wild orchids of Hong Kong /." [Hong Kong : University of Hong Kong], 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1243873X.

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16

Wong, Kwong-chiu Alfred. "Conservation genetics of Hong Kong wild orchids /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2035793X.

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17

Wong, Kwong-chiu Alfred, and 黃廣潮. "Conservation genetics of Hong Kong wild orchids." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31221920.

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18

Qamaruz-Zaman, Faridah. "Conservation genetics of rare and endangered British orchids." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621726.

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19

Tsui, Yuk-chun Prisca, and 徐玉珍. "Conservation and propagation of wild orchids in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1992. http://hub.hku.hk/bib/B31210570.

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20

Kanjilal, Biswajit. "Biotechnological approach towards conservation of certain endangered orchids of North Bengal." Thesis, University of North Bengal, 1999. http://hdl.handle.net/123456789/928.

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21

Roberts, David Lesford. "Reproductive biology and conservation of the orchids of Mauritius." Thesis, Aberystwyth University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367505.

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22

Yam, Tim-wing, and 任添榮. "Conservation, ecology and propagation of the wild orchids of HongKong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231731.

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23

Devey, Dion Stuart. "MARC RecordSystematics and conservation of Mediterranean insect-mimicking orchids (Ophrys)." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.494444.

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Historically, Ophrys morphological taxonomy and species delimitation have been controversial, with treatments inferring from 16 species plus 34 subspecies to as many as 252 species forming 32 complexes. Highly variable, yet possibly convergent, morphologies and paucity of sequence variation have hindered production of a robust phylogenetic framework. This project generated phylogenies and ordinations from nuclear and plastid DNA sequencing, amplified fragment length polymorphism (AFLP) and morphometric data, with the ultimate aims of producing a robust framework as a basis for more rigorous species delimitation and conservation recommendations for the genus. The project also elucidates genetic and morphological relationships within Ophrys section Ophrys, and within the 0. fuciflora and 0. sphegodes aggregates, and assesses the congruence between these contrasting datasets.

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Nam, Kam-shing, and 藍金成. "Conservation of Hong Kong wild orchids by leaf tip culture." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31212591.

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25

Hollick, Penelope Sarah. "Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation." Thesis, Hollick, Penelope Sarah (2004) Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation. PhD thesis, Murdoch University, 2004. https://researchrepository.murdoch.edu.au/id/eprint/103/.

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The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family ? an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity. Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable. Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other. The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct. In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination. Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species. An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stability of the Western Australian landscape. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.

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26

Hollick, Penelope Sarah. "Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae) : implications for conservation /." Hollick, Penelope Sarah (2004) Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation. PhD thesis, Murdoch University, 2004. http://researchrepository.murdoch.edu.au/103/.

Testo completo

Abstract (sommario):

The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family ? an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity. Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable. Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other. The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct. In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination. Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species. An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stability of the Western Australian landscape. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.

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27

Huda, Mohammed Kamrul. "Diversity, ecology, reproductive biology and conservation of orchids of south east Bangladesh." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327403.

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28

au, Hollick@central murdoch edu, and Penelope Sarah Hollick. "Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): Implications for conservation." Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050310.91859.

Testo completo

Abstract (sommario):

The specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity. Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable. Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other. The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct. In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination. Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species. An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stabilityof the Western Australian landscape. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs.

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29

Hurskainen, S. (Sonja). "The roles of individual demographic history and environmental conditions in the performance and conservation of northern orchids." Doctoral thesis, Oulun yliopisto, 2018. http://urn.fi/urn:isbn:9789526220888.

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Abstract (sommario):

Abstract A population growth rate is the sum of all individuals’ reproduction and survival, which in turn depend on many external and internal factors, e.g. weather and individual reproductive history. In plants, for example, previous reproduction can deplete an individual’s resources, resulting in trade-offs between demographic functions. To understand these demographic processes, it is necessary to follow populations for many years. Such long-term studies are especially crucial for endangered species, as they can reveal the causes of population declines and provide information that is directly applicable for the management. In my thesis, I applied this approach to the study of rare orchids. Specifically, I analyzed long-term orchid monitoring data from two countries, Finland and Estonia, to assess the external and internal factors that affect the performance of these long-lived plants, which reproduce both sexually (via seeds) and vegetatively (via new ramets). My research reveals that plant performance depends on both the demographic history and the environment of a plant. For example, although Finnish and Estonian populations of the lady’s slipper orchid, Cypripedium calceolus, differed in direction and statistical significance of their responses to environmental factors, the two most-influential weather variables in both cases were spring snow depth and the temperature of the previous summer. However, the influence of weather on both flowering and vegetative growth was dwarfed by the effect of plants’ own demographic histories: there was a trade-off between current and future reproduction which created asynchronous two-year cycles in reproduction and growth. Furthermore, in all three studied orchid species — the lady’s slipper orchid (C. calceolus), the fairy’s slipper orchid (Calypso bulbosa), and the dark-red helleborine (Epipactis atrorubens) — the probability of dormancy (a state in which the plant spends a year or more underground) and the demographic costs this state incurred with respect to size or future reproduction depended on a plant’s size and whether it flowered prior to dormancy. In other words, dormancy had both absolute and relative costs in large, but not in small, individuals. Finally, I show here that environmental alteration via selective tree removal can be used as a management method to increase orchid reproduction via both seeds and ramets Tiivistelmä Populaation kasvunopeus riippuu siitä, kuinka monta yksilöä populaatioon syntyy ja kuinka monta yksilöä kuolee. Yksilöiden lisääntyvyyteen ja elossa säilyvyyteen puolestaan vaikuttavat monet ulkoiset ja sisäiset tekijät, kuten sää ja yksilön oma lisääntymishistoria. Kasvilla on rajallinen määrä resursseja, joten sen pitää tehdä kompromisseja eri elintoimintojen, esimerkiksi kasvun ja lisääntymisen, välillä. Klonaaliset kasvit voivat myös lisääntyä usealla tavalla: joko suvullisesti siemenistä tai kasvullisesti tuottamalla uusia versoja. Demografisten prosessien tutkimisessa pitkäaikaiset seuranta-aineistot ovat välttämättömiä. Pitkäaikaisseurannat voivat myös paljastaa uhanalaisen lajin populaation taantumisen syyt ja näistä seurannoista saatua tietoa voidaan soveltaa harvinaisten lajien, esimerkiksi kämmeköiden, suojelutoimien suunnittelussa. Tässä väitöskirjassa analysoin aineistoa kämmeköiden pitkäaikaisseurannoista Suomesta ja Virosta. Tavoitteenani oli arvioida ulkoisten ja sisäisten tekijöiden merkitystä pitkäikäisten kasvien menestykselle. Tulokset osoittavat, että kasvin menestys riippuu sekä yksilön omasta demografisesta historiasta että sen ympäristöstä. Eri säätekijöiden vaikutus tikankontin (Cypripedium calceolus) kasvuun ja kukkimiseen vaihteli Suomen ja Viron välillä, mutta lumen syvyys ja edellisen kasvukauden lämpötila nousivat merkittävimmiksi tekijöiksi molemmissa maissa. Tikankontin kasvu ja kukinta riippuivat kuitenkin säätä enemmän kasvin omasta demografisesta historiasta. Runsas lisääntyminen edeltävällä kasvukaudella vähensi lisääntymistä tulevalla kasvukaudella, mikä johti kaksivuotiseen jaksottaisuuteen tikankontin lisääntymisessä ja kasvussa. Tutkiessani dormanssia (lepotila, jossa kasvi ei tuota maanpäällistä versoa) kolmella kämmekkälajilla, tikankontilla, neidonkengällä (Calypso bulbosa) ja tummaneidonvaipalla (Epipactis atrorubens), havaitsin lisäksi, että todennäköisyys siirtyä dormanssiin riippui kasvin koosta. Myöskin tämän lepotilan aiheuttamat kustannukset olivat riippuvaisia kasvin aikaisemmasta tilasta. Isoilla kasveilla dormanssilla oli sekä suoria kustannuksia että kustannuksia suhteessa versomiseen. Pienillä kasveilla näitä kustannuksia ei ollut. Osoitan väitöskirjassani myös, että maltillisella puunpoistolla voidaan lisätä tikankonttipopulaatioiden siementuottoa ja versotiheyttä

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30

Boreau, de Roincé Catherine. "Biodiversité et aménagements fonctionnels en verger de pommiers : Implication des prédateurs généralistes vertébrés et invertébrés dans le contrôle des ravageurs." Phd thesis, AgroParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00952799.

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Abstract (sommario):

L'intérêt des prédateurs généralistes dans la lutte biologique par conservation est peu étudié en verger de pommiers. Cette thèse visait à déterminer le rôle de prédateurs généralistes invertébrés (principalement carabes et araignées) et vertébrés (mésanges et chauves souris) dans le contrôle de trois ravageurs clés du pommier et de définir les éléments paysagers qui leur sont favorables. Pour cela, nous avons effectué des suivis de populations dans des vergers en agriculture biologique et nous les avons associés à des mesures de prédation des ravageurs par analyse moléculaire des contenus stomacaux et faeces des prédateurs à l'aide d'amorces spécifiques développées à cet effet. Nous montrons que les ravageurs sont consommés dès leur apparition dans les vergers, notamment les pucerons par les araignées de la frondaison, ce qui suggère que ces prédateurs ont un potentiel de régulation important. De plus une complémentarité temporelle semble exister entre araignées et carabes dans le contrôle des tordeuses. L'influence des éléments paysagers intra et extra verger diffère selon les taxa de prédateurs considérés. Ce dernier résultat suggère des compromis dans les aménagements à réaliser pour favoriser leur action et la nécessité d'une meilleure compréhension de leur écologie.

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31

Rothé, Marie. "Élaboration d’un outil d’aide à la décision pour la conception de verger agroécologique." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0394/document.

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Abstract (sommario):

La lutte biologique par conservation des habitats est une voie pour réduire la dépendance et l’impact des traitements insecticides qui sont nombreux et toxiques. Elle est particulièrement appropriée pour les vergers d’agrumes qui comprennent, souvent, de grandes surfaces non cultivées. Les auxiliaires présents en plus grand nombre dans un enherbement sont alors plus facilement mobilisables lors d’attaques massives de ravageurs sur les arbres. Ce travail de thèse a pour objectif d’évaluer l’impact des modes de gestion de l’enherbement (fauche, broyage, travail du sol et herbicide) sur les communautés végétales et les populations d’auxiliaires au sein du verger, en s’intéressant à deux communautés évoluant à deux échelles spatiales distinctes : les Phytoseiidae et les Coccinellidae. Nos résultats ont montré une différenciation fonctionnelle des communautés végétales soumises à différents modes de gestion dans le temps. Les Phytoseiidae sont présents en abondances comparables dans toutes ces communautés végétales mais sont cependant influencés par l’abondance dans le couvert des espèces végétales portant des densités de trichomes modérés et des domaties. De même, les abondances de Coccinellidae sont positivement corrélées à l’abondance des Poaceae sur la parcelle alors que les modalités de gestion de l’enherbement testées n’ont pas montré d’effet significatif. Ces connaissances ont pu être mobilisées et articulées pour l’élaboration d’un prototype d’outil d’aide à la décision contribuant à la conception de vergers agroécologiques. Il permet l’évaluation ex ante de scénarios de pratiques de gestion de l’enherbement en vue d’optimiser la lutte biologique par conservation au sein des vergers d’agrumes. Nous avons choisi une approche fonctionnelle qui permettra de généraliser facilement l’outil à d’autres cultures moyennant un élargissement de la base de données comportant les traits fonctionnels aux espèces végétales non renseignées et une bonne connaissance des affinités des auxiliaires que l’on cherche à favoriser Biological control through habitat conservation is a way to reduce the reliance on and the impact of insecticide treatments that are numerous and toxic. It is particularly suitable for citrus orchards which include large areas often uncultivated. The natural enemies present in greater number in a vegetal cover are then more easily mobilized during massive attacks of pests on trees. The aim of this thesis is to evaluate the impact of different weed management methods (mowing, milling, tillage and herbicide) on plant communities and natural enemies populations within the orchard, focusing on two communities that evolve at two distinct spatial scales: the Phytoseiidae and the Coccinellidae. Our results showed a functional differentiation of vegetal communities managed with different weed management methods over time. Phytoseiidae are present in comparable abundances in all these plant communities but are influenced by the abundance of plant species with densities of moderate trichomes and domaties in the vegetal cover. Similarly, the abundances of Coccinellidae are positively correlated with the abundance of Poaceae species on the plot whereas the weed management modalities have no significant impact. This knowledge has been mobilized and articulated for the development of a decision-making tool prototype contributing to the design of agro-ecological orchards. It allows ex ante evaluation of scenarios of weed management practices in order to optimize biological control by conservation in citrus orchards. We have chosen a functional approach which will easily allow to generalize the tool to other crops by expanding the database with functional traits to non-informed plant species and a good knowledge of the affinities of natural enemies to promote

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32

Irvin, N. A. "Understorey management for the enhancement of populations of a leafroller (Lepidoptera: Tortricidae) parasitoid (Dolichogenidea tasmanica (Cameron)) in Canterbury, New Zealand apple orchards." Lincoln University, 1999. http://hdl.handle.net/10182/1111.

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Abstract (sommario):

This study investigated understorey management in Canterbury, New Zealand, apple orchards for the enhancement of populations of Dolichogenidea tasmanica (Cameron) (Braconidae) for leafroller (Lepidoptera: Tortricidae) biological control. The first objective was to determine the influence of understorey plants on the abundance of D. tasmanica and leafroller parasitism, and to investigate the mechanisms behind this influence. The second was to determine the most suitable understorey plants in terms of their ability to enhance parasitoid abundance, leafroller parasitism, parasitoid longevity, parasitoid fecundity and its ability to not benefit leafroller. Results from three consecutive field trials showed that buckwheat (Fagopyrum esculentum Moench), coriander (Coriandrum sativum L.), alyssum (Lobularia maritima (L.) Desv), and, to a lesser extent, broad bean (Vicia faba L.), enhanced parasitoid abundance and leafroller parasitism. The mechanisms behind the effects of understorey plants had previously been unexplored. However, results here showed that it was the flowers or the buckwheat that 'attracted' the parasitoid to the plant and not the shelter, aphids or microclimate that the plant may also provide. Providing flowering plants in the orchard understorey also increased immigration of parasitoids and enhanced parasitoids and enhanced parasitoid longevity and fecundity in the laboratory. In contrast, the understorey plants had no influence on the female:male ratio of D. tasmanica. Although coriander enhanced leafroller parasitism three-fold in field experiments compared with controls, it failed to enhance the longevity of both sexes of D. tasmanica in the laboratory compared with water-only. Broad bean significantly enhanced parasitoid abundance three-fold and significantly increased parasitism from 0% to 75% compared with the controls on one leafroller release date. However, laboratory trials showed that of male D. tasmancia but it did not enhance female longevity. Also, female D. tasmanica foraging on broad bean produced a total of only three parasitoid cocoons, but this result was based on an overall 6.5% survival of larvae to pupae or to parasitoid cocoon. Furthermore, results suggested that extrafloral nectar secretion decreased as the plants matured. Phacelia (Phacelia tanacetifolia Benth.) did not significantly enhance parasitism rate in the field compared with controls, and numbers of D. tasmanica captured by suction sampling were significantly lower in phacelia treatments compared with alyssum, buckwheat and control plots. Also, laboratory experiments showed that survival of D. tasmanica on phacelia flowers was equivalent to that on water-only and significantly lower than on buckwheat. These results suggest that phacelia does not provide nectar to D. tasmanica, only pollen, and therefore is not a suitable understorey plant for D. tasmanica enhancement in orchards. Buckwheat and alyssum showed the most potential as understorey plants for the enhancement of natural enemies. Buckwheat not only increased numbers of D. tasmanica seven-fold, but also increased numbers of beneficial lacewings (Micromus tasmaniae (Walker)) and hover flies (Syrphidae) captured on yellow sticky traps compared with the controls. It significantly increased leafroller parasitism by D. tasmanica from 0% to 86% compared with the controls (on one date only), and in the laboratory enhanced D. tasmanica longevity and increased fecundity compared with water-only. Similarly, alyssum significantly increased parasitism rate compared with controls, and two-fold more D. tasmanica were suction sampled in these plots compared with controls. It also enhanced longevity of both sexes of D. tasmanica compared with water, and showed the most favourable characteristics in terms of being of no benefit to leafrollers. This is because it was not preferred over apple by leafroller larvae and when they were forced to feed on it, it caused high mortality (94.3%) and low pupal weight (15 mg). Furthermore, alyssum did not enhance the number of fertile eggs produced by adult leafrollers compared with water only. However, further research is required to address the overall effect of buckwheat and alyssum on crop production and orchard management, including effects on fruit yield and quality, frost risk, disease incidence, soil quality, weeds and other pests. Also, research into the ability of these plants to survive in the orchard with little maintenance, and into the optimal sowing rates, would be useful. Sampling natural populations of leafroller within each treatment showed that damage from leafrollers and the number of leafroller larvae were respectively 20.3% and 29.3% lower in the flowering treatments compared with the controls. Furthermore, field trials showed up to a six-fold increase in leafroller pupae in controls compared with buckwheat and alyssum. This suggests that increasing leafroller parasitism rate from understorey management in orchards will translate into lower pest populations, although neither larval numbers/damage nor pupal numbers differed significantly between treatments. Trapping D. tasmanica at a gradient of distances showed that this parasitoid travels into rows adjacent to buckwheat plots, indicating that growers may be able to sow flowering plants in every second or third row of the orchard, and still enhance leafroller biocontrol while minimising the adverse effects of a cover crop. Sowing buckwheat and alyssum in orchard understoreys may enhance biological control of apple pests in organic apple production and reduce the number of insect growth regulators applied in IFP programmes. However, the challenge still remains to investigate whether conservation biological control can reduce leafroller populations below economic thresholds.

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33

Freestone, Marc. "Conservation of Prasophyllum - understanding orchid mycorrhizal fungi to save threatened orchids from extinction." Phd thesis, 2022. http://hdl.handle.net/1885/274586.

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Abstract (sommario):

The Orchidaceae are the world's second largest plant family and have a high proportion of threatened species. For some threatened orchids, ex-situ conservation is one of the few options for recovery. However, many orchids are difficult to grow ex situ, an issue complicated by their reliance on orchid mycorrhizal fungi (OMF). Prasophyllum is a large genus of orchids from Australia, with one third of species listed as threatened. However, poor seed germination has consistently affected ex situ conservation efforts. Therefore, the aim of this PhD was to improve ex situ conservation prospects for Prasophyllum by exploring their relationship with OMF, seed viability and propagation methods. Chapter 1 (Annals of Botany, in press) studied the continental-scale diversity and distribution of Ceratobasidium OMF. As Prasophyllum associate primarily with Ceratobasidium OMF, we reviewed published Australian Ceratobasidium OMF data, unpublished Ceratobasidium OMF sequences, and a continent-wide soil sequencing project. Comparing the distribution of OMF isolated from orchids with soil data showed that Ceratobasidium OMF with cross-continental distributions are common, often have geographic ranges exceeding their host orchids, and can tolerate a wide range of environmental conditions. Chapter 2 studied the seasonal dynamics of Ceratobasidium OMF in adult orchids and protocorms. Three Prasophyllum species had different patterns of mycorrhizal associations, ranging from generalist to specific in both adults and protocorms. However, there was no evidence of a seasonal turnover of OMF communities, possibly due to moderate climatic conditions or their association with a single OMF genus. The three orchids did not share OMF, suggesting phylogenetic conservatism or habitat may influence OMF associations. Chapter 3 examined the role of phylogenetic conservatism and habitat in determining mycorrhizal associations in Prasophyllum. We undertook a broad-scale sampling across the Prasophyllum genus, sampling 41 species across nine different sub-generic groups and six habitat types. We showed that both habitat and host orchid taxonomy are correlated with OMF associations in Prasophyllum. Chapter 4 investigated the effect of pollination on reproductive output in Prasophyllum. We tested the effect of pollination treatment (self, cross, natural, none) on three species using tetrazolium staining and asymbiotic germination. Tetrazolium staining showed naturally-pollinated seed had low to moderate viability, depending on the colour of stain scored as viable. However, asymbiotic percentage germination rates were low, and although high viability from staining was correlated with germination, the results of staining could not predict germination rates. Seed viability was not sufficiently low to explain difficulties with germination in Prasophyllum. Chapter 5 developed an asymbiotic germination protocol for Prasophyllum. A broad-spectrum experiment identified a new, low macronutrient asymbiotic medium suitable for the germination of P. frenchii, a counterintuitive finding for an orchid found in fertile soils. However, a previously untested commercial medium supported even higher germination rates, and several other media were optimal for supporting seedling development, although transferral to the nursery caused high mortality. Chapter 6 studied the effect of nutrient media on symbiotic germination of P. frenchii, as propagation with OMF is preferrable for conservation. We observed germination on media high in macronutrients or with an insoluble carbon source, but not on standard oatmeal agar. We trialled three isolates that had similar ITS sequences (>99%), and the optimal medium was different for each, suggesting isolate-level variation in these fungi. The development of effective symbiotic germination has enabled the implementation of ex situ conservation actions for Prasophyllum.

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34

Warantz, Lana. "Sex, lies, & conservation: the design of a botanic garden centred on orchids." 2010. http://hdl.handle.net/1993/3873.

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Abstract (sommario):

Orchid habitat has been destroyed for centuries and as a result many species, some not even discovered yet, have been lost. From the orchid hunters of the 17th and 18th centuries to the deforestation and reckless collection of orchid species today, orchids and their habitats have continued to be at risk. Efforts such as in situ conservation, an approach to protecting orchids in their natural habitat, and ex situ conservation, the protection and propagation of orchids outside their natural habitat in places such as seed banks, laboratories, herbariums, and botanic gardens, have helped to preserve orchid species all over the world. This work includes the design of a botanic garden centred on orchids and their conservation. Situated in Ecuador, the garden design incorporates research, education, and conservation in a way that is inspiring and delightful to the visiting public. Orchids are featured in the design of the garden, and the conservation of this plant family is emphasized. A history of botanic gardens explores the evolution of this specific type of garden, providing a background for modern-day design. Case study analyses of contemporary botanic gardens provides additional information and insight into the changing role of botanic gardens in the 21st century. This Practicum explores the creation of an educational garden that is also entertaining and challenges the notion of what a botanic garden is today and what it can be in the future.

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35

Janes, JK. "Subtribe Pterostylidinae : a multidisciplinary approach to investigating and resolving taxonomic confusion." Thesis, 2010. https://eprints.utas.edu.au/10706/2/whole-thesis-janes.pdf.

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Abstract (sommario):

The distribution, niche-partitioning, taxonomy and population-level genetic variation of Tasmanian representatives of the subtribe Pterostylidinae were investigated. General ecological data were collected over a two year period to assess changes in the known distribution of Pterostylis species within Tasmania and identify previously unknown populations. Ecological characteristics relating to habitat were used to perform a series of canonical correspondence analyses (CCA) to effectively delimit each species’ ecological tolerances and niche hyperspace. A series of Bayesian and maximum parsimony phylogenetic reconstructions were conducted using DNA sequence data from the internal transcribed spacer (ITS) region of nuclear ribosomal DNA to elucidate generic and infrageneric relationships within the Pterostylidinae. Following from these results, the genetic variation within the Tasmanian members of the “longifolia” species complex was investigated using amplified fragment length polymorphism (AFLP) and polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Ecological survey data indicated that the distribution and abundance of Pterostylis species within Tasmania had changed significantly within the past 10 years, with different species apparently more or less common than previously thought. In addition to the number of populations located, the number of individuals within each population provided insight into the overall level of conservation status applicable to particular species and several recommendations for the management of these species were made. Niche partitioning based on habitat characteristics revealed differences in the ecological tolerances of Pterostylis species and effectively delimited many species along ecological gradients. Significant overlap in the fundamental niches of several morphologically similar species was identified, which suggested that some taxa within Pterostylidinae complexes had been incorrectly assigned to the level of species. This hypothesis was later confirmed through a phylogenetic and population genetic study. Phylogenetic work using ITS sequence data confirmed that Pterostylidinae is embedded within the tribe Cranichideae. Furthermore, the reconstructions strongly supported a monotypic subtribe (Pterostylidinae) comprising the single genus Pterostylis R.Br sensu lato. The analysis found two strongly supported clades that correlated with the morphology of the lateral sepal position within the subtribe and, are herein, delimited as subgenera of Pterostylis. Several closely related species from within species complexes had identical ITS sequences; together with the CCA data the results indicate the presence of over-splitting of the Pterostylidinae. PCR-RFLP analysis of the chloroplast genome in the “longifolia” species complex revealed extremely low variation among species and no marker was found that could distinguish between the Tasmanian representatives of this complex. Further work at the population level using AFLP markers indicated high levels of polymorphism within the complex but, again, could not delimit the four “longifolia” species. Instead, population structure analysis revealed geographic separation of “longifolia” populations irrespective of species. The information from these investigations is essential for taxonomic resolution within the subtribe Pterostylidinae and has clear implications for Pterostylis conservation and management

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36

Thompson, David Ian. "Conservation of select South African Disa Berg. species (Orchidaceae) through in vitro seed germination." Thesis, 2003. http://hdl.handle.net/10413/5579.

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Abstract (sommario):

Disa comprises 163 species, 131 of which occur in South Africa (SA). The genus is distributed across winter- and summer-rainfall areas, but few species transverse both climatic regions. Species are therefore regarded as winter-rainfall or summer-rainfall endemics - yet release their seeds in autumn, irrespective of provenance. Disa contributes 40 % of threatened Orchidaceae in SA, with half of the local species requiring conservation initiatives. In vitro seed germination is a potential conservation tool for producing large numbers of genetically diverse plants in relatively short periods. However, only 11 winter-rainfall Disa species are easily germinated ex situ. Studies were therefore undertaken on summer-rainfall taxa, which are ungerminated in vitro, in an effort to define their germination parameters. This thesis describes mechanisms that control germination in Disa and establishes practical propagation methods for seed culture. Two seed types occur in Disa; i) comparatively large, pale and pyriform seeds in members of the D. uniflora sub-c1ade, which populate streamside habitats under conditions of winter-rainfall maxima, and ii) smaller, variously brown and fusiform seeds in the remainder of the genus. Seed morphometrics distinguished seed types, although embryo dimensions were similar. Testa continuity, which is disrupted in the large seeds, also supported separation. Typically, small seeds are ungerminated in vitro, whilst large seeds germinated readily. Increased seed size did not necessarily impart increased germ inability, as several germinable, small-seeded species exist - being winter-rainfall species Attempts to establish in vitro germinability revealed that increased water availability and charcoal supplementation promoted germination in intractable species. The control of germination was therefore proposed as a trade-off between water availability and the presence of phyto-inhibitors - two features typical of seeds exhibiting water-impermeable dormancy. Three germinability categories were recognized; i) easily germinable species, ii) poorly germinable species through media manipulation, and iii) ungerminated species. Germination of immature seed in the absence of media modification was comparable to mature seed germination under modified conditions, providing evidence of the role of an impermeable seed testa in regulating germination. Testa impermeability in mature, small-seeded species was demonstrated using aqueous EVANS' blue dye and was linked to i) testa integrity and ii) increased levels of leachable phenolics (LPC) - which are hydrophobic and phytotoxic. In addition, this research revealed an impervious and elaborate embryo carapace in small seeds. Large-seeded species were highly permeable at dehiscence, with perforated testae and negligible LPC. Germinability was ultimately defined by a significant regression with LPC. Phenolic deposition increased exponentially with increasing seed maturity and reflected decreased permeability and the development of testa colouration. The testa precludes the use of viability stains such as nc and FDA, unless rendered permeable through scarification. This was achieved using NaOCI. Viability and germinability percentages did not correlate well for the small-seeded Disa species, indicating that i) the methods used to break dormancy are inadequate, ii) additional factors may be acting in concert with the testa to regulate germination and iii) that the determination of mature Disa seed viability is ineffective. As an alternative, the germination potential of immature seed was estimated as the ratio between the proportion of embryos stained with TTC and the proportion of seeds permeable to EVANS' blue. Attempts to relieve water-impermeable dormancy in Disa resulted in the formulation of a dual-phase protocol - with the specific aim of increasing water availability to the embryo. Dual-phase cultures comprised a solid, charcoal-rich medium overlaid with a reduced strength, liquid medium fraction of the same type. The solid fraction negated the influence of leached phenols and allowed protocorms to establish polarity, whilst the fluid fraction increased water availability. The dual-phase protocol allowed germination of nine summer-rainfall Disa species, usually in percentages that approximated their estimated germination potential. For the remaining species, germination is controlled by more complex factors. Large seeds are atypical in containing starch, the hydrolysis of which facilitated their rapid, autonomous germination. Small-seeded Disa species stored lipids and proteins and germinable species accumulated starch post-germination. The embryo protoplasts of all species contained appreciable amounts of soluble sugars, irrespective of germinability. However, decreased sucrose and increased fructose correlated significantly with decreased seed germinability. This study provides evidence of the nutritional value of mycotrophy, with endophytes liberating soluble carbohydrate and non-carbohydrate compounds upon lysis. However, few species were germinated symbiotically, suggesting that endophytes isolated from adult roots do not necessarily support germination in the same species. Similar endophytic fungi occur in Australian and Holarctic orchids. Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

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Tesi sul tema "Orchid conservation"

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