Dissertations / Theses on the topic 'Endangered plants'
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1
Robertson, Emma. "TRANSITIONS: Biophilia, Beauty and Endangered Plants." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/17875.
Abstract:
While the science continues to underline the increasing risks posed by climate change, rallying the public to the cause has proved increasingly difficult. A major challenge is finding alternatives to the despair, hopelessness and consequent sense of disempowerment that confronting the realities of climate change can provoke. It is also the case that particular silent aspects of the impact of climate change – for example on the future viability of certain plant species – receive less public and political attention than others, such as catastrophic weather events. Artists have been active in exploring the impact of climate change through a variety of aesthetic strategies in attempts to address these challenges and mobilise complex understandings of the phenomenon. The response of this thesis is to focus on a specific issue and location – endangered Australian plants – and to experiment with a range of different artistic approaches, filtered through the lens of biophilia and beauty. The experimental artwork produced builds and demonstrates a bridge between botanical science, endangered plant species, and art, in relation to climate change. The PhD research makes four substantial contributions. First, it presents a different perspective on the applied use of art as a mode of enquiry into climate change, through creative agency and advocacy on the focused theme of endangered Australian plants. Second, the research explores and assesses alternative methods for making and reconceptualising static drawings into moving images, as a strategy to engage artistically and positively with the negative ecopsychology and ecoanxiety of climate change. Third, newly initiated, collaborative projects with non-arts partners are deployed to enhance audience engagement through the application of drawings. In parallel to this, conventional international and national exhibitions, publications and workshops are also realised as additional contributions to knowledge within different communities. Fourth, the research results in a document which explores a hopeful reconnection with nature through applying and embracing an aesthetic of beauty and meditative mindfulness. A Transmedia Art method is utilised to enhance broader community understanding of Eco Art, using a mindful, practice based research process.
2
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.
3
Filipski, Jules. "Reproductive biology of the endangered plant, Phlox hirsuta (E.E. Nelson)." View full-text version online, 2005. http://soda.sou.edu/awdata/060221b1.pdf.
Abstract:
Thesis (M.S.) --Southern Oregon University, 2005."A thesis submitted to the Department of Biology and the Graduate School of Southern Oregon University in partial fulfillment of the requirements for the degree of Master of Science in Science." Includes bibliographical references (p. 69-75) Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.
4
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.
5
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.
Abstract:
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.
6
Xego, Sibusiso. "Hydroponic propagation of Siphonochilus aethiopicus: an endangered medicinal plant." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2421.
Abstract:
Thesis (MTech (Horticultural Sciences))--Cape Peninsula University of Technology, 2017.The increasing demand for medicinal plants has led into serious over-harvesting of wild populations and presents an opportunity for potential profitable cultivation. Production of medicinal plants in controlled environments particularly hydroponic technology provides opportunities for high quality biomass accumulation and optimizes production of secondary metabolites. Water availability and supplies are becoming scarce, thus search for innovative irrigation practices is desirable and vital. The proper irrigation interval and growing media can play a major role in increasing the water use efficiency. Thus, Siphonochilus aethiopicus was cultivated by means of the hydroponic technique, under various substrate combinations and watering regimes.
7
Grant, Marissa Catherine Jernegan. "Survival strategies of the endangered Physaria ludoviciana (silvery bladderpod; Brassicaceae) /." View online, 2009. http://repository.eiu.edu/theses/docs/32211131592147.pdf.
8
Mosime, Bonolo. "In vitro conservation of selected endangered plant species indigenous to the Cape Floristic Region, South Africa." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2343.
Abstract:
Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2016.This study focused on optimising four types of in-vitro conservation methods, namely: 1), micropropagation, 2) in-vitro slow growth, 3) seed germination and 4) cryopreservation for selected endangered plant species indigenous to the Cape Floristic Region. It is one of the targets set by United Nations millennium development goals, to integrate different conservation measures in order to preserve plant diversity and mitigate losses of genetic diversity. Therefore this study uses Phalaenopsis hybrids as a trial species that can be studied for the conservation of endangered Disa and Eulophia species through micropropagation and in vitro slow growth. Also conservation attempts on Leucadendron and Mimetes species that occur in the Cape Floristic Region were attemted to increase population densities by increasing germination percentages using smoke. Furthermore, the study attempted to store seeds by assessing different cooling rates for optimising cryopreservation measures for effective conservation. The use of tissue culture to increase propagules especially critically endangered species in South African has proven to be feasible. For the trial hybrids, shoot and protocorm explants of Phalaenopsis Psychosis Pink X P. No. 1; P. Large white X P. Large pink; P. No. 1 X P. Large pink; P. Mini pink X Brighton belle; and the P. aphrodite formed clusters of protocorms and shoots when cultured on ½ strength MS media supplemented with 10, 20 and 30gL-1 banana extract or ½ strength Murashige and Skoog, (1962) (MS) media supplemented with peptone. Continuous protocorms formation could therefore be obtained by culturing endangered Disa and Eulophia shoots and protocorms on banana containing media. Plantlet conversion from somatic embryos produced on 10gL-1 banana extract enriched media was successfully achieved on ½ strength MS supplemented with 20gL-1 sucrose and no plant growth regulators in the medium. However, optimum rooting was achieved on ½ strength MS supplemented with 30gL-1 of banana extract and this medium yielded the highest survival percentages for plantlet acclimatisation. Furthermore, ½ strength MS supplemented with 1gL-1 of peptone served as a stimulant for shoot development and protocorm formation. When coupled with banana extract at all stages of development, regeneration and rooting were enhanced.
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.
10
Walker, Charles Henry. "Biological and ecological attributes of some endangered vascular plants of southern Illinois /." Available to subscribers only, 2007. http://proquest.umi.com/pqdweb?did=1324370471&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
11
Mlungwana, Asanda. "In-vitro propagation studies of the endangered succulents Drosanthemum Micans and Drosanthemum Hallii (Aizoaceae)." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2748.
Abstract:
Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2018.Drosanthemum micans and Drosanthemum hallii are endangered succulent shrubs of horticultural and medicinal value. They are restricted to the Succulent Karroo, which is one of the world’s biodiversity hotspots. The species risk extinction from illegal over-harvesting for water-wise gardens, erosion by occasional flush floods from ephemeral rivers, competition from alien invasive species, overgrazing and clearing of land for agriculture and human settlement. Although seeds and cuttings may be used in propagating these species, they often require seasonal collection and planting and cuttings struggle to establish, hence the need for in-vitro propagation as an alternative solution. Thus, the main objective of the study was to develop a method for rapid in-vitro shoot and root multiplication and acclimatization of D. micans and D. hallii. To initiate shoot formation, disinfected leaf and stem nodal explants were cultured in Murashige and Skoog (1962) media supplemented with different rates (0, 10, 20 or 30μM) of 2-isopentyladenine, 6-Benzyladenine and kinetin for D. hallii or 2-isopentyladenine, 6-Benzyladenine and Thiadiazuron for D. micans. Shoots from explants were rooted in varying rates (0, 10, 20 or 30μM) of IAA for root initiation. Three media, which were used in previous studies, were tested for acclimatization of rooted explants in i) vermiculite, ii) sand (50%): vermiculite (50%) or iii) sand (75%): perlite (25%). For quantitative evaluation of plant stress, chlorophyll fluorescence index (Fv/Fm) was measured as a proxy for plant stressf stress. It emerged that stem nodal explants of D. hallii tend to produce multiple shoots whilst leaf explants tended to produce callus when cultured in full-strength Murashige and Skoog (1962). Shoot multiplication was optimal in both D. hallii and D. micans at 10 μM of kinetin. Root formation in both D. hallii and D. micans only occurred when shoots were transferred to a full-strength Murashige and Skoog (1962) media without any phytohormones added. The intensity of tissue browning increased at higher levels of cytokinins, suggesting an interaction of plant growth regulators with exudates from explants. Different acclimatization media tested showed no significant differences in the level of stress (Fv/Fm). It is recommended that Murashige and Skoog (1962) media with10 μM kinetin be used for shoot development and multiplication, followed by transfer of the shoots to fresh full-strength Murashige and Skoog (1962) media without hormones for root development. Acclimatization of the rooted explants was possible in one of the following media: i) vermiculite, ii) sand (50%): vermiculite (50%) or iii) sand (75%): perlite (25%) and in a misted greenhouse (ca. 60% RH), with gradual weekly reductions in humidity by 10% over 2 weeks.
12
Kunzelman, Jennifer I. "Does ultraviolet radiation induce changes in the photophysiology and photochemistry of Halophila johnsonii Eiseman? /." Electronic version (PDF), 2003. http://dl.uncw.edu/etd/2003/kunzelmanj/jenniferkunzelman.html.
13
Demirci, Barbaros. "A Geographic Information Systems Tool Development For Geostatistical Analysis Of Endangered Endemic Vascular Plants Of Turkey." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606098/index.pdf.
Abstract:
Modern information systems strive to provide effective use of resources. Supplied with analysis tools, geographical information systems (GIS) can serve its stakeholders with minimal requirements. In this study, GIS capabilities were employed for Turkish Flora. Data related with the threatened plants that are indigenous to Turkey were gathered from the relevant literature and reshaped into a dataset in which spatial locations were represented in a geographically referenced format. Afterwards, this output was used to investigate the affects of different factors on the distribution patterns of these plants by means of functions of GIS and multivariate analysis. At last, overlay analysis was employed in
order to reveal the congruence between official protection reserves, spatial locations of the plants in danger and areas of importance for other elements of wildlife specifically birds.
Outcomes of the study is three-fold. First of all, a simple algorithm was established which can be used in the formation of a unified database of widely distributed floristic data in Turkey. Geographically referenced data and the analysis results produced in the study is another value added for Turkish botanics. From another perspective, effectiveness of GIS in handling different types of non-standard data were scrutinized. Overlay analysis of locations of the plants and the protection reserves constituted the managerial aspect of the study by pointing large gaps in the actual protection coverage and proposing candidate regions for official reserve
choices of the future. In essence, GIS was deemed to be an effective tool for parties working on non-standard spatial data.
14
Walker, George Floyd. "Analysis of molecular variation in the federally endangered Astragalus jaegerianus (Fabaceae, Papilionoideae): A species with a restricted geographic range." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2743.
Abstract:
The purpose of this study is to investigate the level and distribution of genetic variation in Astragalus jaegerianus by using molecular markers. The objectives of the study are: to estimate levels of genetic variation within and among populations of Astragalus jaegerianus; to test the hypothesis that levels and patterns of genetic variation in species of restricted ranges and few individuals is low and partitioned at the population level; and to discern whether, or how well, genetic partitioning of Lane Mountain milk vetch correlates with its geographic partitioning in the field.
15
Glimskär, Anders. "Growth strategies, competition and defoliation in five grassland plants /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5465-4.pdf.
16
Burke, Jennifer L., and 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.
Abstract:
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.
17
Rivers, Malin C. "Range-wide analysis of the spatial distribution and genetic diversity of Delonix s.l. (Leguminosae) in Madagascar : enhancing herbarium-based conservation assessments." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/2097.
Abstract:
Despite their ecological and economic importance, the majority of plant species and their conservation status are poorly known. Only 4% of plants have been assessed globally and listed on the IUCN Red List of Threatened Species; and without plant conservation assessments, many plant species will not feature in conservation planning. Herbarium collection information can significantly increase the number of plant conservation assessments. Thus, the aims of this thesis were: (1) to investigate how the quality of herbarium-based conservation assessments can be optimised; (2) to assess the extent to which herbarium-based conservation assessments reflect the reality on the ground; and (3) to scientifically validate genetic and spatial underpinning of IUCN criteria. Preliminary range-based assessments of the Leguminosae of Madagascar achieved a result consistent with the final conservation rating for over 95% of species when using up to fifteen herbarium specimens. Bioclimatic modelling of range shifts based on future climate change predicted that, in the worst case scenario, up to one third of endemic Leguminosae in Madagascar will be threatened with extinction over the next 100 years. An analysis of the population structure of species of Delonix s.l. (Leguminosae) showed that combining spatial analysis with population genetic data provides a more complete picture of landscape-level population dynamics and the impacts on conservation status. Moreover, range-wide genetic analysis of AFLP markers for four species of Delonix demonstrated a genetic basis for IUCN categories distinguishing between threatened and non-threatened species. Although genetic data are currently not often incorporated in conservation assessments, they are crucial in making accurate management decisions and creating effective action plans for conservation. Only by using all available scientific resources can informed conservation decisions be made and the survival of plants and their associated ecosystems be ensured.
18
Gustavsson, Eva. "Grassland plant diversity in relation to historical and current land use /." Uppsala : Dept. of Ecology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/2007106.pdf.
19
Bussara, Tirakalyanapan Sittipong Dilokwanich. "The cooperation between government agency and environmental NGOS : a case study on convention on international trade in endangered species of wild fauna nad flora /." Abstract, 2005. http://mulinet3.li.mahidol.ac.th/thesis/2548/cd379/4537409.pdf.
20
Bates, Thomas Hathaway. "Sclerocactus wrightiae (Cactaceace): An Evaluation of the Impacts Associated with Cattle Grazing and the Use of Remote Sensing to Assess Cactus Detectability." BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8986.
Abstract:
The Wright fishhook cactus (Sclerocactus wrightiae L.D. Benson) is an endangered cactus species endemic to south-central Utah. Since its listing in 1979 by the U.S. Fish and Wildife Service, the potential impacts of soil disturbance by cattle have become a central focus of management policies and monitoring efforts. However, little to no empirical data has been collected to substantiate the hypothesis that soil disturbance by cattle has direct or indirect negative effects on Wright fishhook cactus growth or reproduction. Over the years, the Bureau of Land Mangement (BLM) and Capitol Reef National Park (CRNP) have invested significant resources documenting cactus populations including several attributes of individual cacti: GPS location, diameter, number of flowers, fruits, or buds, number of stems, and the presence or absence of a cow track within 15 cm of the cactus. While these efforts have been commendable, due to the defining phenological characteristics of this species (flower and filament color) and its short flowering period (April-May) it remains difficult to study and much basic biological information including a range wide population estimate and defined critical habitat remain unknown. Our research had two primary objectives, 1) evalutate the effects of soil disturbance by cattle on reproduction and diameter of the Wright fishhook cactus (Chapters 1 and 2), and 2) explore the use of drones and GIS to define critical habitat and obtain an accurate range wide population estimate (Chapters 3 and 4). In Chapter 1, we analyzed cactus attribute data collected by the BLM at 30 macro-plots representing different levels of soil related cattle disturbance (high, moderate, and low) from 2011-2017. We found no significant association between level of cattle disturbance and flower density or cactus diameter. We did find a significant negative association between flower frequency and increased disturbance. In Chapter 2, we conducted an experimental study where tracks were simulated within 15 cm of cacti at various levels (Ctrl, 1-Track, 2-Track, 4-Tracks, and 4-Tracks Doubled). No significant association was observed between the number of tracks and response in diameter, flower production, fruit production, or seed set. In Chapter 3, we conducted drone flights over 14 macro-plots at three different altitudes above ground level (10 m, 15 m, and 20 m) and found that while the 10 m flights provided the best remotely sensed survey results, drones are not a suitable replacement for ground censuses. In Chapter 4, we used Resource Selection Function to define critical habitat for the Wright fishhook cactus. Our modeling suggests that geology, elevation, and slope are significant factors in defining cactus habitat. Based on the results of our research we conclude that soil disturbance by cattle may not have a significant influence on Wright fishhook cactus populations or dynamics, and that accurate range wide population estimates may be best obtained through ground surveys within the predicted critical habitat.
21
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.
Abstract:
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.
22
Rudolphi, Jörgen. "Bryophytes, lichens and dead wood in young managed boreal forests /." Uppsala : Dept. of Ecology, Swedish University of Agricultural Sciences, 2007. http://epsilon.slu.se/200788.pdf.
23
Kreivi, M. (Marjut). "Conservation genetics and phylogeography of endangered boreoarctic seashore plant species." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514290190.
Abstract:
Abstract
The amount and distribution of genetic diversity are likely to affect the evolutionary potential of a species. When feasible and cost-effective policies for management and monitoring of endangered populations or species are planned, knowledge of the spatial genetic structure and the type of population dynamics is of great concern. In this thesis the genetic diversity and population structures of two endangered arctic plant species was examined on different geographical scales in Northern Europe. The species were Siberian primrose (Primula nutans) and pendant grass (Arctophila fulva), which both grow in a seashore habitat and have similar distribution patterns on the shores of the Arctic Ocean and the Bothnian Bay.
The goal of the present study was to provide basic population genetic information for the study species using microsatellite and AFLP markers. Both markers were used for the first time in these species, and species-specific microsatellite markers were developed during the study. A further aim was to interlink the population genetic processes of the species into distribution patterns at the regional and population levels and to compile a synthesis of the impact of hierarchical spatiotemporal processes and autocorrelation in genetic variation at different levels.
The studies of this thesis provided new information on the diversity and population structure of the endangered study species and new markers that are useful in future genetic studies of primrose species. The diversity of Siberian primrose was low, and there was no dispersal between the study regions. In pendant grass, a relatively high amount of variation was found considering the evident clonal reproduction and gene flow that was detected between populations connected by waterways. The results suggested that both clonal and sexual reproduction are important in this species. On a local scale, pendant grass populations had characteristics of “stepping stone” and classical metapopulation models.
The results indicated that on a long time scale, both species will continue to decline without efficient management efforts. Most critical for the persistence of the species is the conservation of suitable habitats. Translocations could be considered in order to enhance the diversity of existing populations and establish new populations.
By examining the present day structure of Siberian primrose, it was possible to make inferences regarding the colonisation history of the species in the North European area. The current distribution of Siberian primrose seemed to result from a vicariant process that took place after the last ice-age, when the species colonised the area. It spread first to the White Sea area, probably from the east, and subsequently colonised the Bothnian Bay and the Barents Sea in the west. The isostatic land uplift after the retreat of the Eurasian ice sheet uncovered large areas of land from the Baltic Sea basin that previously were under water. These geological changes resulted in the current disjunct distribution of Siberian primrose.
24
Johnson, Connie Nicole. "Stem cutting propagation of the endangered species, Clematis socialis (Kral)." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Fall/Theses/JOHNSON_CONNIE_58.pdf.
25
Hattenbach, Meryl Jennifer. "Edaphic relations of an endangered plant, Trifolium stoloniferum Muhl. ex A. Eaton." Connect to resource, 1996. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1261052966.
26
Reiter, Noushka Hedy, and noushka reiter@dse vic gov au. "Borya mirabilis steps in the recovery of a critically endangered Australian native plant." RMIT University. Applied Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090227.160625.
Abstract:
Borya mirabilis is one of the world's most critically endangered plants. The research in this thesis has illuminated key aspects of: its reproductive biology; interspecies and intraspecies molecular relationships, mycorrhizal status, tissue culture potential and disease threats. Each of these aspects has fundamental management implications for the active management of B. mirabilis. Floral observations of B. mirabilis and related species affirmed the uniqueness of the Boryaceae amongst the Asparagales. B. mirabilis had an unusually high number of floral abnormalities compared with other species of Borya observed. B. mirabilis is fly-pollinated. Pollen of Borya species showed little difference in the characteristics of mature pollen between species, with viable pollen being prolate and unicolpate with a single colpa-style aperture and a unique patterning of the pila. The structural immaturity of B. mirabilis pollen correlated with evidence from pollen growth experiments, where B. mirabilis pollen had extremely low germination rates, with those grains that did germinate being slow to do so and with slow-growing pollen tubes compared to those of fertile Borya species. Examination of the ovules of B. mirabilis showed that morphologically they were viable compared to viable Borya species. The field population of B. mirabilis was crossed, with one seed produced (the first recorded seed for th is species). Cross-pollination using the pollen of the closely related B. constricta and B. sphaerocephala with B. mirabilis ovules proved unsuccessful. Examination of the chromosome number of B. mirabilis showed that it had approximately 66 chromosomes and is probably hexaploid, relative to the diploid number of 26 in B. constricta. This may explain its low fertility. Interspecies and intraspecies relationships of the Boryaceae and Borya mirabilis were investigated using sequences of chloroplast and nuclear DNA. The closest similarities to B. mirabilis were B. constricta and B. sphaerocephala. B. mirabilis may have emerged from alloploidy of these species in the past. Because of the consistent similarities of B. mirabilis and B. constricta chloroplast sequences, it is proposed that both shared a common ancestor with a chromosome number of 2n=22. A malfunction n meiosis may have resulted in ovules with 2n=44. The high similarity of the nuclear ribosomal ITS region DNA suggests that the nuclear DNA was derived from B. sphaerocephela. B. mirabilis may be an allopolyploid, from fertilisation of a diploid ovule of B. constricta with haploid pollen of B. sphaerocephala, resulting in a reproductively isolated polyploidy of low fertility. The wild population of B. mirabilis was determined to have a small amount of genetic variation. The genetic variation in the field population w as not fully reflected in the ex-situ population. An effective means of micro-propagation of B. nitida for use in B. mirabilis has been established, providing an effective means of mass production of the species. The research has determined: a suitable explant (shoot tips) for regeneration; an effective means of reducing contamination in tissue culture (PPM); what medium is required to micro-propagate the species (LMHM); an appropriate gelling agent (Phytagel); and a practical method for inducing roots on the shoots grown in tissue culture. B. mirabilis has been established as mycorrhizal. The predominant mycorrhizal association is a nodular arbuscular mycorrhiza, present in the form of coils in root nodules over wetter months and as spores in these nodules over dryer months. A significant increase in the health of the ex-situ population of B. mirabilis was recorded after addition of soil containing fine roots of the wild population. Of the plants associated with the wild population, Callitris rhomboidea had the most morphologically similar vesicular arbuscular mycorrhizal relationship. But molecular identification was not achieved due to recalcitrance of DNA in PCR attempts. Potential translocation sites for some of the ex-situ population of B. mirabilis were examined for Phytophthora infestation. Reid's Lookout and Mackey's Peak were infected with P. cinnamomi. Vegetation at Mackey's Peak displayed characteristic infection symptoms, resulted in isolates of P. cinnamomi from baiting and would directly receive runoff from both the walking track and the existing infested B .mirabilis site. At the Reid's Lookout site, both walking track and proposed translocation site were infested with P. cinnamomi, yet did not display the associated symptoms in the vegetation. The Pine Plantation translocation site was uninfected at the level of sampling undertaken. Its vegetation did not display any characteristic infection symptoms and was not isolated when soil samples were baited. It was therefore chosen for translocation and so far the plants are healthy and actively growing. This research has provided critical knowledge to aid the recovery team in its current and future endeavours to manage this species and bring it back from the brink of extinction.
27
Symonds, Josephine Elizabeth. "Patterns and ecological consequences of exotic plant invasion in Canada's endangered antelope-brush ecosystem." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/33719.
Abstract:
Exotic species invasion is a serious threat to ecosystem structure and function throughout the world. In an effort to understand and limit the future effects of invasion, recent research has focused on quantifying and predicting patterns of exotic plant invasion based on abiotic and biotic features, particularly native species diversity, over multiple spatial scales. I investigated native-exotic richness relationships (NERRs) and their scale-sensitivity and predictability within the antelope-brush (Purshia tridentata Pursh (DC)) shrub-steppe grasslands of the South Okanagan Valley, British Columbia, one of Canada’s four most endangered ecosystems and a national hot spot of biodiversity and endemism. I applied for the first time the concept of focus, which describes one aspect of observational scale, to the NERR and built upon previous studies to determine how different components of scale influence the NERR. I found that the NERR was affected by changing the grain but not the focus or extent of analysis in the antelope-brush grasslands. Contrary to the prevailing hypothesis, I found a highly significant positive NERR at the finest grain and focus (i.e., 1 m²) that appeared to be influenced at least in part by preferential facilitation of exotic plants by antelope-brush shrubs. Also contrary to expectations from the literature, I found no association between exotic and native species richness at the broadest grain and focus (i.e., 1,000 m²), and that mean environmental conditions and variation in these conditions failed to account for significant variation in broad focus exotic species richness in this system. These unexpected results challenged me to re-examine my data in light of other possible hypotheses and to develop a novel interpretive framework that provides a theoretical explanation for all possible NERR results given a particular focus of analysis and study system. Although correlative, the patterns observed in this study may simplify the scope of exotic plant management in the antelope-brush grasslands, as they suggest that broad focus environmental heterogeneity has limited influence on species richness. However, the indication that biotic factors, particularly facilitation by antelope-brush shrubs, influence exotic species richness and abundance at fine focuses poses unique challenges to conservation efforts in this endangered ecosystem.
28
Shiu, Y. B. Ivan, and 蕭猷斌. "Saving the endangered longest beach of Hong Kong: enhancing public awareness on coastal and global climateproblems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38219268.
29
Marberg, Mikael. "Phippsia concinna in Sweden : Exploring ecological dependencies in a regionally endangered plant species that occurs in alpine snowbeds." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-101244.
Abstract:
The purpose of this study is to 1: Get an updated population estimate for the regionally endangered alpine specialist plant Phippsia concinna in Sweden and 2: Explore the ecological dependencies that limits the distributions of this species to late melt-out alpine snowbeds on calcareous soils, and 3: Explore if climate change in the southern part of the Scandes mountain range is causing a decline in the population numbers of P. concinna. The majority of the sites in Sweden where P. concinna occurred historically was inventoried in 1992. This study presents the results of a re-inventory of the same snowbeds after 22 years, along with measurements of abiotic soil factors and records of abundance and composition of associated vegetation at the sites. The main findings are 1: Population number of P. concinna has increased but one third of the original populations has disappeared since 1992, and 2: Soil pH appears to limit the distributions of P. concinna while slope aspect and soil Nitrogen concentrations affects this species competitive abilities in the Swedish Scandes. 3: Presence of P. concinna is negatively correlated to cover of other graminoids and bryophytes. These results suggests that snowbeds are melting earlier following increased temperatures and precipitations in summer, resulting in longer vegetation periods that favours plant species with stronger competitive abilities over specialised snowbed species. The observed rate of change in P. concinna populations during 22 years is evidence of fast occurring vegetation changes and highlights the need to monitor rare plant species in alpine environments.
30
Pickens, Bradley A. "THE CONSEQUENCES OF A MANAGEMENT STRATEGY FOR THE ENDANGERED KARNER BLUE BUTTERFLY." Bowling Green State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1149173870.
31
Yayan, Wahyu Candra Kusuma. "Ecological and genetic studies of endangered plant species, Vatica bantamensis and Rafflesia spp., for developing optimal conservation strategies in Indonesia." Kyoto University, 2019. http://hdl.handle.net/2433/244560.
32
Correa, Cano María Eugenia. "Macroecological patterns of plant species and anthropogenic activities." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/22975.
Abstract:
The study of macroecology not only identifies patterns in the distribution and abundance of species at large spatial and temporal scales, it also gives insight into the processes underlying those patterns. The contribution of this work is not limited to helping develop the field of ecology per se, but also provides important insights into the understanding of large scale processes like climate change, the spread of introduced species, pest control and how increasing pressure from anthropogenic activities threatens biodiversity and ecosystem services. During the first decade following its formal inception, most of the progress in macroecology was made through studies of animal species, and research into plant species continues to lag far behind. This thesis contributes to the study of the macroecology of plant species by examining some selected macroecological patterns that have been studied only for animal species and by including an important issue that might have significant effects on diverse macroecological patterns, namely anthropogenic activities. The second and third chapters of the thesis address the generalised individuals-area relationship (GIAR) and the patch individuals-area relationship (PIAR), two macroecological relationships not previously explored for plant species. I show for the first time the existence of negative GIARs at the intraspecific and interspecific levels in plant species, similar to those documented for animal species. Unlike animal species, I did not find a broadly consistent intraspecific PIAR in plant species; more than half of the tested species showed negative PIARs. The resource concentration hypothesis may help explain those positive PIARs that were observed. The fourth chapter considers the effect of past human activities on current patterns of plant species richness at a landscape scale. Using a detailed database on the historical anthropogenic activities for Cornwall, U.K., I examine the relationship between species richness and the area covered by each historical land-use at two different spatial resolutions (10km x 10km and 2km x 2km). I find that at the 10km x10km scale human activities carried out since the 17th and 19th centuries explain an important proportion of the variation in current plant species richness. In contrast, a model at 2km x 2km scale with upland woods and the total land area of a grid cell explain only 5% of the variation. The fifth and sixth chapters focus on how artificial light at night (ALAN), which has increasingly come to attention as a significant anthropogenic pressure on species, is interacting with the distributions of plant species. In the fourth chapter, I consider the plant family Cactaceae to determine the proportion of the global distribution ranges of species that is being influenced by ALAN, and how this changes with the size of these distribution ranges and over a 21-year period (1992 to 2012). I found that >80% of cacti species are experiencing ALAN somewhere in their distribution range, and that there is a significant upward trend in ALAN in the ranges of the vast majority of species. For the sixth chapter, I consider similar issues for the threatened plant species of Britain, exploiting new remote sensing imagery of nighttime lighting at a very fine spatial resolution (c.340x340m2). Only 8% of Britain is free of artificial light at night and in consequence a high number of threatened plant species have a high proportion of their range under some influence of ALAN.
33
Everard, David Alexander. "The conservation status of some unique plant communities in the Eastern Cape." Thesis, Rhodes University, 1986. http://hdl.handle.net/10962/d1007497.
Abstract:
In response to a growing concern over the rising rates of extinction of the world's plants and of habitat destruction, studies of Southern African threatened plants were initiated in the 1970's. These studies, which have largely concentrated on Western Cape flora, led to the publication of "Threatened Plants of Southern Africa" by Hall et al., 1980, which attempted to list as many threatened or possibly threatened species as possible. It was however marred by a lack of recent herbarium records and detailed studies from many parts of the region, the Eastern Cape being one of these. In order to extend these detailed studies to gain a clearer picture of the numbers of threatened species in the Eastern Cape and evaluate the conservation status of Eastern Cape vegetation this project was initiated. Initially lists of possibly threatened and endemic taxa of the Eastern Cape were compiled from various sources. These listed taxa were then checked against herbarium records, all available information being filled onto index cards for filing purposes. This paper-based filing system was then transferred into a computer-based data bank to facilitate the efficient storage and retrieval of information. Results from this data bank show that there are 662 variously threatened plant taxa in the Eastern Cape, many of which fall into temporary categories which need to be clarified by investigation in the field. Primarily based on the above results, a table ranking the various vegetation types into an order of priority for investigations about conservation requirement was developed.Subtropical Thicket was found to be the vegetation type in most need of investigation and so an extensive phytosociological survey was carried out in the Valley Bushveld which forms the major portion of Subtropical Thicket in the Eastern Cape. Twelve sites were sampled for floristic and environmental variables along a rainfall gradient of between 300 mm yr⁻¹ and 1 000 mm yr⁻¹ and along a longitudinal gradient from the Buffalo River in the east to the Gamtoos-Kromme complex in the west. Floristic data W(re analysed using multivariate techniques of classification and ordination. A classification by two-way species indicator analysis revealed the Valley Bushveld to consist of two orders of thicket, the Kaffrarian Succulent Thicket containing the two suborders, Inland Succulent Thicket and the Coastal Succulent Thicket and the Kaffrarian Thicket containing Coastal Kaffrarian Thicket and Inland Kaffrarian Thicket. Ordina tion by detrended correspondence analysis also grouped sites according to these vegetation categories in a sequence along one axis, to which the rainfall gradient could be related. Variables such as diversity indices, numbers of endemics, numbers of threatened taxa and structural features were also extracted from the data and these were correlated with environmental variables by multiple regression analysis. Species richness and the percent woody component w\!re positively correlated with rainfall while endemism and percent succulent component were strongly negatively correlated with rainfall. Most of the other relationships were explained by interrelationships with rainfall. Finally the sites were evaluated according to floristic criteria indicative of conservation value. The Coastal Succulent Thicket appeared to have the highest conservation value mainly owing to high endemism, while Inland Kaffrarian Thicket was also important as it supports a high number of species. The thickets with high conservation value are therefore the thickets of coastal areas in the western parts of the Eastern Cape which receive a low rainfall and the thickets which receive a rainfall in excess of 800 mm.KMBT_363
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Hudgens, Faith Victoria. "AN ASSESSMENT OF STREAM QUALITY IN RELATION TO POPULATION HEALTH OF PLANTAGO CORDATA." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2887.
Abstract:
Understanding the health of rare and at-risk plant species is crucial for the conservation of biodiversity. Rare and at-risk species are often specialists with very specific requirements for growth and reproductive success. Some parameters associated with growth and reproductive success of rare aquatic species may include biotic and abiotic factors such as herbivory, competition, water depth, pH, and other factors associated with habitat quality. In this thesis, the population health of the rare and at-risk aquatic species Plantago cordata in Southern Illinois streams is assessed in relation to stream quality of sites containing Plantago cordata and sites without Plantago cordata.The objectives of this study were to (1) Determine if there is a relationship between population size structure and biotic habitat factors among populations and sites, and (2) Determine if there is a relationship between population size structure and abiotic habitat factors among populations and sites. Hypotheses were constructed using the hierarchy-of hypotheses method and most narrow alternative hypotheses are as follows: (1) There will be significant relationships between biotic and abiotic factors and Plantago cordata growth and reproductive success. (2) Levels of herbivory will have significant relationships with growth and reproductive success of Plantago cordata. (3) The abundance of co-occurring species individually and considered in functional groups (graminoid, herb, woody) will have significant relationships with growth and reproductive success of Plantago cordata. (4) Stream depth will have a unimodal relationship with growth and reproductive success of Plantago cordata, with maximum performance at an intermediate stream depth. (5) Stream pH will have a unimodal relationship with growth and reproductive success of Plantago cordata. (6) Stream quality (as outlined by the QHEI assessment) will have significant relationships with growth and reproductive success of Plantago cordata. General trends in herbivory suggest that Plantago cordata could be at greatest risk of herbivory during warmest average temperatures of the study season. There is evidence to suggest that flowering individuals could have a greater threat of herbivory than other growth stages based on Kendal correlation results. A Wilcox test determined that there were no statistical differences in species richness for plots with versus without Plantago cordata. There were relatively low values for percent cover of co-occurring species when considered in functional groups and there was overall relatively low species richness across all communities. Despite this, non-metric multidimensional scaling (NMDS) of community data provided evidence to suggest that there were statistical differences in the species composition of co-occurring individual riparian species among P. cordata populations. A significant negative correlation for water depth and flowering individuals and a significant positive correlation with water depth and pH occurred. A significant positive correlation for stream pH with the numbers of seedlings and dehiscing individuals was also found. One-way analyses of variance (ANOVAs) showed that some populations containing Plantago cordata were found to have stream pH values statistically different from nearby IEPA control streams without Plantago cordata. One population of Plantago cordata was found to be significantly different than two other populations in regards to stream pH using a linear mixed model. A principal components analysis (PCA) of stream Qualitative Habitat Evaluation Index (QHEI) assessments demonstrated distinct clustering of Plantago cordata streams and control IEPA streams without Plantago cordata. These findings provide partial evidence to suggest that growth and reproductive success of Plantago cordata could potentially be impacted by the abiotic and biotic parameters explored in this thesis.
35
Erguner, Baytok Yasemin. "Population Status, Threats And Conservation Approaches For A Highly Threatened Endemic Plant, Centaurea Tchihatcheffii Fisch. &." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12610122/index.pdf.
Abstract:
Centaurea tchihatcheffii Fisch. &Mey. is a critically endangered annual endemic plant found only in Ankara. This study aimed to determine its distributional range, metapopulation status, the effects of agricultural activities, and assess conservation options. Occurrences and population size estimates were carried out by ground surveys. Two adjacent subpopulations were intensively studied during 2004-2008. Plant and seed demographic data were collected in the field and by laboratory tests. Field experiments simulated the effects of agricultural practices. Risks of extinction and possible impacts of different management actions were investigated through a population viability analysis (PVA) by constructing a two-stage stochastic model. Six scenarios involving different management actions were run with 10,000 replications each using RAMAS Metapop. A total of 14 patchily distributed subpopulations were found to have an extent of occurrence of >
700 km2. Herbicide applications caused extreme mortality and reduced germination success, and were shown to be the major anthropogenic threat against long-term survival of C. tchihatcheffii. Tillage led to an increase in density and reproductive success in the following year. PVA simulations for most scenarios predicted extinction of both subpopulations within 4 to 95 years, but a conservation management scenario involving delayed tillage ensured viable populations with a combined size of 21 million individuals. PVA results demonstrated that timing and frequency of tillage is crucial. Therefore, we propose tillage to be carried out after seed set every other year for protected subpopulations to ensure their long term persistence. Alternatively, unprotected subpopulations elsewhere can benefit from organic or nature-friendly farming.
36
Handel, Kevin. "Testing Local Adaptation Of The Federally Endangered Karner Blue Butterfly (Lycaeides Melissa Samuelis) To Its Single Host Plant The Wild Lupine (Lupinus Perennis)." Bowling Green State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1429214530.
37
Braidwood, David Walter. "Remediation and restoration of ocean exposed cliff-top, in the context of Dounreay (Scotland) nuclear power plant decommissioning." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237241.
Abstract:
Restoration ecology continues to become ever more relevant as legislation demands we prevent biodiversity losses. Post-industrial restoration sites pose a number of additional challenges, including balancing ecological need with logistical and financial constraints. In the North of Scotland, one such site is the Dounreay Nuclear Power Plant, now undergoing decommissioning. The intention is to restore cliff-top habitat with native vegetation, blending in with its surroundings and necessitating minimal maintenance. The overall objective of this PhD research was to help develop a plan for the restoration of the site. A key challenge in this particular case was the residual low level radioactivity at depth in some areas, and a restoration layer is required to prevent contamination of bioreceptors at the surface, however, topsoil availability is limited. The cliff top site, and exposure to salt spray driven by strong winds, meant the identification of suitable vegetation communities for different areas could be crucial to its success. Vegetation and soil surveys across nine reference sites along the North coast of Scotland identified five non-peat vegetation communities suitable for Dounreay's restoration. Restoration ecology continues to become ever more relevant as legislation demands we prevent biodiversity losses. Post-industrial restoration sites pose a number of additional challenges, including balancing ecological need with logistical and financial constraints. In the North of Scotland, one such site is the Dounreay Nuclear Power Plant, now undergoing decommissioning. The intention is to restore cliff-top habitat with native vegetation, blending in with its surroundings and necessitating minimal maintenance. The overall objective of this PhD research was to help develop a plan for the restoration of the site. A key challenge in this particular case was the residual low level radioactivity at depth in some areas, and a restoration layer is required to prevent contamination of bioreceptors at the surface, however, topsoil availability is limited. The cliff top site, and exposure to salt spray driven by strong winds, meant the identification of suitable vegetation communities for different areas could be crucial to its success. Vegetation and soil surveys across nine reference sites along the North coast of Scotland identified five non-peat vegetation communities suitable for Dounreay's restoration. This prompted the development of a novel concept: that of utilising restoration sites as 'protorefuges' or 'protorefugia', i.e. restoration sites where threatened species at the leading edge of climate change can be translocated ahead of the climate changing. There, they would be joined by individuals of the wider population naturally dispersed as the climate shifts. Overall, these results enabled the development of a refined restoration plan for Dounreay, which takes into account the particular setting, constraints and timelines involved. With the decommissioning of an increasing number of nuclear sites across Britain and Europe taking place in the coming years, this research should be developed further. In particular our novel concept of protorefugia could even be put into practice, benefiting both restoration and conservation.
38
Snyder, Melissa. "Ecological and Genetic Variation Among Populations of Boechera caeruleamontana sp. nov. (Brassicaceae) from Blue Mountain and Dinosaur National Monumentin Eastern Utah and Western Colorado." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6344.
Abstract:
Boechera is a large genus of flowering plants whose taxa are found primarily in North America. Boechera vivariensis (S.L. Welsh) W.A. Weber (the Park rockcress) is restricted to the Uintah Basin on Weber sandstone substrates in the vicinity of Dinosaur National Monument and Blue Mountain. The nomenclature of Park rockcress is significantly impacted by the discovery that the type collections of the taxon represent a rare, apomictic diploid resulting from the hybridization between B. thompsonii and an undescribed sexual diploid (to be called Boechera caeruleamontana sp. nov. Allphin and Windham). As a result, greater information is needed regarding how B. vivariensis and B. caeruleamontana. are distributed geographically in the region of Dinosaur National Monument and surrounding areas. Thus, we performed genetic analyses on leaf samples taken from over 50 individuals at known sites of B. vivariensis throughout its geographic range. Individuals from each site were also compared morphologically. We also compared associated plant communities at each site and characterized the soils. In our thorough sampling, we did not pick up B. vivariensis. All individuals sampled belonged to B. caeruleamontana, suggesting that most individuals previously assigned to B. vivariensis, are actually representative of B. caeruleamonanta. Populations of B. caeruleamontana were genetically diverse compared to other Boechera species, most likely indicative of its insect pollination strategy. However, all populations had lower heterozygosity than expected based upon Hardy-Weinberg expectations. Reproductive and genetic data indicated that populations are showing signs of inbreeding. The population at Jones Hole Fish Hatchery was most unique genetically, morphologically, and reproductively.
39
Planchuelo, Gregorio [Verfasser], Ingo [Akademischer Betreuer] Kowarik, Moritz von der [Akademischer Betreuer] Lippe, Ingo [Gutachter] Kowarik, Moritz von der [Gutachter] Lippe, and Jonathan [Gutachter] Jeschke. "Urbanisation impacts on rare and endangered plant species / Gregorio Planchuelo ; Gutachter: Ingo Kowarik, Moritz von der Lippe, Jonathan Jeschke ; Ingo Kowarik, Moritz von der Lippe." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1196200130/34.
40
Windhager, Steven. "An assessment of the use of seeding, mowing, and burning in the restoration of an oldfield to tallgrass prairie in Lewisville, Texas." Thesis, Connect to this title online, 1999. http://www.library.unt.edu/theses/open/19992/windhager%5Fsteven/index.htm.
41
Jonsell, Mats. "Insects on wood-decaying polypores : conservation aspects /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5627-4.pdf.
42
Pereira, Ismael Martins. "Ecologia, conservação e aspectos taxonômicos do gênero neotropical Davilla Vand. (Dilleniaceae)." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/59/59139/tde-30072014-110731/.
Abstract:
Neste trabalho realizou-se o estudo de distribuição, riqueza e conservação do gênero Davilla Vand. (Dilleniaceae) no Neotrópico. Para tal utilizou-se a modelagem de distribuição de espécies com o algoritmo Maxent. Este produz distribuição das espécies no espaço geográfico a partir de dados ambiental e de ocorrência. Foram estudadas as espécies de acordo com o bioma de ocorrência: Mata Atlântica; Cerrado; e Amazônia. Este grupo está representado no Neotrópico por 25 espécies. Para o Cerrado incluiu-se além das espécies do gênero Davilla as demais espécies da família Dilleniaceae. Os resultados indicaram que no Cerrado o grupo está representado por nove espécies de Davilla, além de Curatella americana L. e três espécies de Doliocarpus Rol., destas cinco são endêmicas (Doliocarpus elegans Eichler e 4 Davilla spp.). Para a Mata Atlântica ocorrem 12 espécies de Davilla, oito delas são endêmicas, incluindo uma espécie ameaçada de extinção. Para a Floresta Amazônica são conhecidas nove espécies, cinco delas endêmicas. Duas outras espécies são Neotropicais, portanto, compartilhadas por todos os biomas citados anteriormente. As demais espécies são de ocorrência em pelo menos dois biomas. Para estes três biomas produziu-se a distribuição e a riqueza de espécies visando comparar os resultados com as unidades de conservação, objetivando discutir questões relativas à conservação deste grupo. Os parâmetros conservacionistas como espécies raras, zonas de endemismo, zonas de alta riqueza, áreas de preservação ambiental, foram confrontados objetivando indicar áreas prioritárias para a conservação do grupo e da biodiversidade. Os resultados indicaram existir três centros de diversidade para este grupo. O principal deles está localizado na Mata Atlântica, principalmente nas florestas litorâneas do estado da Bahia. Outro centro de diversidade localiza-se na região central do Cerrado, especialmente nos estados de Goiás e Bahia. A outra área de diversidade localiza-se próximo à foz do Rio Amazonas e ao longo de seu curso. Devido ao hábito predominante das espécies serem lianas, estas são importantes componentes das florestas, das quais usamos este referencial para discutir questões relativas à conservação destes habitats, de suas espécies e da biodiversidade. As informações completas estão apresentadas nos capítulos de acordo com os respectivos biomas abordados.In this study was realized to study the distribution, richness and conservation of the Davilla Vand. (Dilleniaceae) in the neotropics. For this purpose was used to distribution model of species with Maxent algorithm. This produces species distribution in geographic in space based on environmental and occurrence data. Species in accordance with biome of occurrence were studied: Atlantic Forest; Cerrado; and the Amazon. This group is represented by 25 species in the neotropics. For the Cerrado was included in addition to the Davilla species all species of Dilleniaceae family. The results indicated that in the Cerrado this group is represented by nine species of Davilla, and Curatella americana L. and three species of Doliocarpus Rol., to these five are endemic (Doliocarpus elegans Eichler and 4 Davilla spp.). For Atlantic Forest occur 12 Davilla species, eight of which are endemic, including an endangered species. For the Amazon are known nine species, five of these endemic. Two other neotropical species are therefore shared by all biomes mentioned above. The other species are occurring in at least two biomes. For these three biomes produced the distribution and species richness in order to compare the results with the protected areas, aiming to discuss issues relating to the conservation of this group. Conservationists parameters as rare species, areas of endemism, areas of high species richness, conservation areas, were confronted aiming indicate priority areas for conservation of biodiversity and too this group. The results indicated three centers of diversity for this group. The main one is located in the Atlantic Forest in coastal forests of Bahia. Another center of diversity is located in central region of Cerrado, especially in the states of Goias and Bahia. The other area of diversity is located near the mouth of the Amazon River and along its course. Due to the prevailing habit of the species are lianas, these are important components of forests, of which we use this framework to discuss issues relating to the conservation of these habitats, their species and biodiversity. Full details are presented in chapters according to their biomes addressed.
43
Bruce, Jessica. "Phylogeography and population structure of the putative relict Reedia spathacea F.Muell. (Cyperaceae)." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2441.
Abstract:
Lineages which have persisted from Gondwana and remain restricted to mesic habitats with fragmented distributions are often considered relicts. Relictual taxa belong to formerly more common groups that have become isolated phylogenetically by extinction and/or geographically by changes in climate and habitat availability. The south-west region of Australia is a biodiversity hotspot containing flora that are Gondwanan in origin. Within this region are restricted remnants of mesic habitat that host taxa not found elsewhere, including the endemic sedge Reedia spathacea F.Muell. (Cyperaceae). The species is found in refugial peat swamps and was described as a relict in the process of being listed as critically endangered, based on its unique morphology and its shared habitat with known relicts. However, R. spathacea is poorly understood, not well documented, and its purported relictual status has not been addressed.
This study investigates the Gondwanan relictual status of R. spathacea through the application of criteria distilled from the literature. These are, to assess restriction to habitat that is atypical of the region, phylogenetic distinctiveness, lineage age, and population dynamics. Utilising life-history and morphology data from R. spathacea, molecular phylogenetics and dating, population genetics and phylogeography, this study finds that the lineage Reedia belongs to is phylogenetically distinct, with a clear early divergence and originates from the Gondwanan landmass. Further, populations are found to be recently genetically isolated, likely a result of contraction into refugia. These data showed that R. spathacea met all criteria to be considered a Gondwanan relict.
Implications of these findings are considered for the conservation of R. spathacea, as measures currently undertaken do not best serve the biology of the species. In particular, R. spathacea has characteristics suggestive of adaptation to fire, has more than one recruitment strategy, and is capable of invading refugial habitats, or outcrossing with existing populations. These aspects of Reedia are not currently taken into consideration, in favour of conservation measures to address threat and stochasticity. This study successfully demonstrates that the use of all criteria to assess relicts is applicable to taxa other than R. spathacea, and that a concerted effort to uniformly apply these criteria is needed to better understand purported relicts. This is important so that conservation is no longer only reflective of vulnerability but adequately addresses characteristics unique to relicts
44
Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." Thesis, The University of Sydney, 2006. http://hdl.handle.net/2123/1896.
Abstract:
A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.
45
Davila, Yvonne Caroline. "Pollination ecology of Trachymene incisa (Apiaceae): Understanding generalised plant-pollinator systems." University of Sydney, 2006. http://hdl.handle.net/2123/1896.
Abstract:
Doctor of Philosophy (PhD)A renewed focus on generalised pollinator systems has inspired a conceptual framework which highlights that spatial and temporal interactions among plants and their assemblage of pollinators can vary across the individual, population, regional and species levels. Pollination is clearly a dynamic interaction, varying in the number and interdependence of participants and the strength of the outcome of the interaction. Therefore, the role of variation in pollination is fundamental for understanding ecological dynamics of plant populations and is a major factor in the evolution and maintenance of generalised and specialised pollination systems. My study centred on these basic concepts by addressing the following questions: (1) How variable are pollinators in a generalised pollination system? To what degree do insect visitation rates and assemblage composition vary spatially among populations and temporally among flowering seasons? (2) How does variation in pollinators affect plant reproductive success? I chose to do this using a model system, Trachymene incisa subsp. incisa (Apiaceae), which is a widespread Australian herbaceous species with simple white flowers grouped into umbels that attract a high diversity of insect visitors. The Apiaceae are considered to be highly generalist in terms of pollination, due to their simple and uniform floral display and easily accessible floral rewards. Three populations of T. incisa located between 70 km and 210 km apart were studied over 2-3 years. The few studies investigating spatial and temporal variation simultaneously over geographic and yearly/seasonal scales indicate that there is a trend for more spatial than temporal variation in pollinators of generalist-pollinated plants. My study showed both spatial and temporal variation in assemblage composition among all populations and variation in insect visitation rates, in the form of a significant population by year interaction. However, removing ants from the analyses to restrict the assemblage to flying insects and the most likely pollinators, resulted in a significant difference in overall visitation rate between years but no difference in assemblage composition between the Myall Lakes and Tomago populations. These results indicate more temporal than spatial variation in the flying insect visitor assemblage of T. incisa. Foraging behaviour provides another source of variation in plant-pollinator interactions. Trachymene incisa exhibits umbels that function as either male or female at any one time and offer different floral rewards in each phase. For successful pollination, pollinators must visit both male and female umbels during a foraging trip. Insects showed both preferences and non-preferences for umbel phases in natural patches where the gender ratio was male biased. In contrast, insects showed no bias in visitation during a foraging trip or in time spent foraging on male and female umbels in experimental arrays where the gender ratio was equal. Pollinator assemblages consisting of a mixture of different pollinator types coupled with temporal variation in the assemblages of populations among years maintains generalisation at the population/local level. In addition, spatial variation in assemblages among populations maintains generalisation at the species level. Fire alters pollination in T. incisa by shifting the flowering season and reducing the abundance of flying insects. Therefore, fire plays an important role in maintaining spatial and temporal variation in this fire-prone system. Although insect pollinators are important in determining the mating opportunities of 90% of flowering plant species worldwide, few studies have looked at the effects of variation in pollinator assemblages on plant reproductive success and mating. In T. incisa, high insect visitation rates do not guarantee high plant reproductive success, indicating that the quality of visit is more important than the rate of visitation. This is shown by comparing the Agnes Banks and Myall Lakes populations in 2003: Agnes Banks received the highest visitation rate from an assemblage dominated by ants but produced the lowest reproductive output, and Myall Lakes received the lowest visitation rate by an assemblage dominated by a native bee and produced the highest seedling emergence. Interestingly, populations with different assemblage composition can produce similar percentage seed set per umbel. However, similar percentage seed set did not result in similar percentage seedling emergence. Differences among years in reproductive output (total seed production) were due to differences in umbel production (reproductive effort) and proportion of umbels with seeds, and not seed set per umbel. Trachymene incisa is self-compatible and suffers weak to intermediate levels of inbreeding depression through early stages of the life cycle when seeds are self-pollinated and biparentally inbred. Floral phenology, in the form of synchronous protandry, plays an important role in avoiding self-pollination within umbels and reducing the chance of geitonogamous pollination between umbels on the same plant. Although pollinators can increase the rate of inbreeding in T. incisa by foraging on both male and female phase umbels on the same plant or closely related plants, most consecutive insect movements were between plants not located adjacent to each other. This indicates that inbreeding is mostly avoided and that T. incisa is a predominantly outcrossing species, although further genetic analyses are required to confirm this hypothesis. A new conceptual understanding has emerged from the key empirical results in the study of this model generalised pollination system. The large differences among populations and between years indicate that populations are not equally serviced by pollinators and are not equally generalist. Insect visitation rates varied significantly throughout the day, highlighting that sampling of pollinators at one time will result in an inaccurate estimate and usually underestimate the degree of generalisation. The visitor assemblage is not equivalent to the pollinator assemblage, although non-pollinating floral visitors are likely to influence the overall effectiveness of the pollinator assemblage. Given the high degree of variation in both the number of pollinator species and number of pollinator types, I have constructed a model which includes the degree of ecological and functional specialisation of a plant species on pollinators and the variation encountered across different levels of plant organisation. This model describes the ecological or current state of plant species and their pollinators, as well as presenting the patterns of generalisation across a range of populations, which is critical for understanding the evolution and maintenance of the system. In-depth examination of pollination systems is required in order to understand the range of strategies utilised by plants and their pollinators, and I advocate a complete floral visitor assemblage approach to future studies in pollination ecology. In particular, future studies should focus on the role of introduced pollinators in altering generalised plant-pollinator systems and the contribution of non-pollinating floral visitors to pollinator assemblage effectiveness. Comparative studies involving plants with highly conserved floral displays, such as those in the genus Trachymene and in the Apiaceae, will be useful for investigating the dynamics of generalised pollination systems across a range of widespread and restricted species.
46
Gilfedder, Louise. "Aspects of the conservation biology of Helipterum albicans (Hook.) P.G. Wilson." Thesis, 1991. https://eprints.utas.edu.au/19594/1/whole_GilfedderLouise1993_thesis.pdf.
Abstract:
The straw daisy Helipterum albicans ssp. albicans var. incanum (Hook.)
P.G.Wilson forme incanum is endangered, and is in serious risk of
disappearing from the wild within one or two decades if present land use and
other causal factors continue to operate. H. albicans may have been a
naturally rare species, but its current endangered status is the result of
anthropogenic processes. It is a species that occurs in temperate grassy
ecosystems, the vegetation type most altered for grazing and agriculture.
H. albicans was once more widespread in its distribution, but currently it is
restricted to a small number of fragmented and scattered populations in north
west and central Tasmania on land that is managed for grazing. Floristic data
were collected from 24 sites where H. albicans occurs, and five floristic
groupings were recognized. These were from sites at altitudes ranging from
60 m to 1200m on soils derived from basalt, mudstone, glacial and lateritic
deposits, and in areas with both high and low mean annual rainfall.
Genotypic and phenotypic variation were established for different populations
of H. albicans in terms of morphology, germination and response to
experimental treatments.
H. albicans has a high rate of seed production, and the seeds have virtually no
dormancy period and require no special treatment to stimulate germination.
Moderate to high germination success is achieved at a range of temperatures
from 5-30°C. H. albicans has an achene with a well developed pappus suited
to wind dispersal, and the wind dispersal of large quantities of seed which
form a transient and short-lived seedbank appears to be a more critical strategy
for regeneration than seed stored in the soil. Germinates of H. albicans
represented less than 2% of the total number of individuals that germinated
from the soil seed bank.
H. albicans is not palatable to domestic stock, and there was little evidence of
insect or animal predation. Exclosure studies revealed that H. albicans was a
species that benefits from stock grazing in two principal ways. Grazing results
in the soil disturbance necessary for regeneration, and reduces the biomass of
the dominant grasses, allowing the establishment and growth of herbaceous
species. The exotic composite Hypochoeris radicata is abundant in the soil
seed bank and germinates earlier than Hypochoeris, giving it a competitive
advantage. Glasshouse studies established Hypochoeris is able to supress the
growth of H. albicans when they are grown together.
H. albicans will require active conservation management in the form of weed
control, grazing and a suitable fire regime to ensure its survival in the wild.
47
Madubanya, Lebogang Angelo. "In vitro conservation of endangered Dierama species." Thesis, 2004. http://hdl.handle.net/10413/10089.
48
Chang, Li-Wan, and 張勵婉. "Vegetation and Rare, Endangered Plants in the Wulai Area." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/13374488359194371985.
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Hartzell, James Francis. "Response of the endangered medicinal plant : Siphonochilus aethiopicus (Schweif) B.L. Burt. to agronomic practices." Thesis, 2011. http://hdl.handle.net/10413/10037.
Abstract:
This study examines field cropping constraints for domestication of an endangered, wild medicinal plant, Siphonochilus aethiopicus, (Schweif.) B.L. Burt. Extensive literature review and careful observations of plant growth behavior during two years of crop trials overturned several long-held but erroneous claims that have consistently appeared in the scholarly literature, and revealed previously undocumented plant growth characteristics. S. aethiopicus (Schweif.) B.L. Burt. is a rhizomatous corm, not a rhizome. Field growth observations demonstrated clearly that the false stem and leaves grow continuously from emergence in September to senescence in April-May; the corm retains its tuberous roots during winter senescence, and is genetically preprogrammed to shoot in September. Flowers may emerge throughout the growing season (not only initially prior to shoot emergence), typical leaf count is 11-15, not 6-8 as previously reported, numbers that remain constant even when the plant height increases by 20-30% under shade, and leaf distichy is independent of the sun’s course and is unaffected by mother corm orientation. S. aethiopicus proved to be unusually resistant to common field diseases and pests, and resilient to severe hail.
The responses of S. aethiopicus were tested in a series of field trials to the effects of levels of compost, field spacing, size of planting material, addition of biocontrol agents, different degrees of shading, and factorials of the macronutrients Nitrogen, Phosphorous and Potassium. Spacing-Composted chicken litter combinations were tested in 2005-2006 in factorial combination with Spacing at 15 cm-4.5 kg ha-1, 20 cm-7.5 kg ha-1, 30 cm-10 kg ha-1, and 40 cm-15.5 kg ha-1, and these treatments were randomized with 4 Corm planting sizes (height by base diameter in mm): Small (S, 12.38 mm x 12.6 mm), Medium Small (MS, 29.65 mm x 27.93 mm), Medium Large (ML, 38.48 mm x 37.78 mm) and Large (L, 52.37 mm x 44.10 mm). 2005-2006 ANOVA tests showed significant differences between Spacing-Compost and Corm Size for the total harvest biomass measure, with 30 cm and 40 cm spaces better than 15 cm spacing, and Corm Size MS, ML and L all better than S, and ML better than MS. Total Corms harvested per block and
ii
Survival Percentage were similarly significant for Corm Size, but not Spacing. Corms smaller than the Small criteria were raised separately, under optimal conditions in a nursery. In a separate 2005-2006 Compost-only trial ANOVA tests did not find significant differences between compost levels.
In 2006-2007 we tested Spacing separately at 5, 10, 15, 20, 30 and 40 cm between planted corms in each plot. We tested Compost levels separately, with 0, 5, 10 and 15 kg ha-1 compost per plot. In 2006-2007 only the ML and L sizes were used in an even mix. There were no significant differences between treatments due to high experimental error, but measurement across all production parameters showed a clear trend towards best performance at spacing between 20 and 40 cm. Overall the results from the Spacing, Compost-level and Corm Size trials suggest that 30 cm is perhaps the optimal field spacing, higher compost levels tend to give better results, and the ML and L corm sizes perform better in open-sun field trials. These parameters are recommended for further field studies and production.
The effects of two commercial strains of Trichoderma spp were tested at recommended doses applied to S. aethiopicus. T. harzianum Strain B77 was used as a drench at planting in comparison with a Control and a fungicide in 2005-2006. There were no significant differences between treatments for Harvested Biomass or Survival Percentage. B77 did perform significantly better than the Fungicide in the Total Corm measurement, but neither treatment was significantly different from the Control. In sum, there was a weak trend towards a greater number of output corms as a result of the application of the biocontrol agent. In both 2005-2006 and 2006-2007 we tested T. harzianum Strain kd applied as a drench at planting, with a second drench at 4 weeks. In 2006-2007 there were no significant differences between treatments, but the trend was towards better performance as a result of the drench at planting only.
In 2005-2006 open field trials had shown that S. aethiopicus is susceptible to sunburn and Erwinia soft rot when grown in the full sun. Therefore, we tested the effect of various shadecloth densities and colours on production performance in 2006-2007. Treatments were Control (full sun), 40% White (TiO2) (23% shade), 40% Grey (28-30% shade), Light Black (40%), Medium Black (50%), Dark Black (80%), and Red (40%).
There were no significant differences between treatments, but the trends indicated that the Control (full sun) and Dark Black (80% shade) performed the worst. Colour of shade did not appear to be important, and plants under all the shadecloths with 40-50% shade grew best. In a factorial trial different levels of Nitrogen, Phosphorous, and Potassium (NPK)were tested, over two seasons. Four levels of each input were used: N at 0 (Control), 40 kg ha-1 (N1), 80 kg ha-1 (N1), and 120 kg ha-1 (N3). P levels were 0 (Control) 60 kg ha-1 (P1) ,120 kg ha-1 (P2) and 200 kg ha-1 (P3). K levels were 0 (Control), 100 kg ha-1 (K1), 200 kg ha-1 (K2), and 400 kg ha-1 (K3). In 2005-2006 there were no significant differences between treatments. In 2006-2007 data there were significant results for Nitrogen only within each repetition. However, significance disappeared when combining across repetitions. We then ran a Bootstrap re-sampling analysis of both 2005-2006 and 2006-2007 data (data were analyzed separately because of different plot sizes and corm numbers in the two years), looking at the optimal level of each macronutrient tested against all combinations of the other two. Though significant results were obtained for each individual level of each macronutrient against the others in combination, the difference between the confidence intervals was not significant. However, there was a clear trend: the optimum N levels were between 40 and 80 kg ha-1; optimum P level was 0 (the Control) and optimum K levels were between 100 and 200 kg ha-1.
Tests of handling during harvest, storage, and planting yielded additional useful information for small scale commercial farmers. The optimal harvest time is May, when the false stem and leaves are senescing and yellow, but still upright and visible. Harvest is facilitated by moistening the soil to minimize breaking off of tuberous roots, with simple field washing to remove compacted soil highly recommended. Harvested corms and tuberous roots should be stored under air-restricted, cool conditions because the tuberous roots contain high moisture and will shrivel quickly when left exposed to air, and excessively dried corms will eventually die. Senesced mother corms should be discarded at harvest. Corms are genetically preprogrammed to shoot, so should be planted in September in soft soil, with 1-2 cm of soil coverage.
The studies provide a framework for developing the basic agronomy for the domestication and commercial crop production of an endangered medicinal plant species.Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
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Chauke, Hlayisa Michael. "Mavito ya swimila swa ndhavuko eka Xitsonga eka ndhawu ya ka Malamulele exifundzeni xa Limpopo." Thesis, 2007. http://hdl.handle.net/10386/2293.