An understanding of the effects of harvest on wild plant populations is essential for discerning the ecological impacts of past and present human uses of wild species, and for conserving species which are currently overexploited. This dissertation builds on theories and methods to describe and predict the impacts of harvesting non-timber forest products (NTFP) through an ethnoecological study of the terrestrial bromeliad Aechmea magdalenae. A. magdalenae is harvested from the rainforests of South-eastern Mexico where it has a long history of exploitation. The fiber extracted from its leaves is used to embroider leather articles in an artwork known as piteado. The sustainable harvest of this species has been promoted in Mexico as a strategy to conserve forests and provide local people with a stable income. / A combination of demographic, ethnobotanical and participatory methods was used to quantify harvest strategies, measure their impacts on A. magdalenae populations, and assess potential for cultivation. The impacts of harvesting: (1) ramets used for forest plantations; (2) leaves and ramets; (3) and whole plants and ramets, were measured by comparing the dynamics of harvested and nonharvested populations. The demographic implications of variation in the ecological and human context of harvest were examined. The effects of variation in traditional management and traditional knowledge of this species were also quantified. / Analyses using matrix models indicate that primary forest populations harvested for their ramets are declining due to overexploitation. Secondary forest populations are tolerant to ramet harvest and show elevated rates of growth and vegetative propagation in wild and cultivated plants. High rates of fiber harvest have little impact on population growth rates and increase A. magdalenae's tolerance to ramet harvest. The economic and ecological implications of local harvesting strategies vary within regions as well as between regions with short and long histories of A. magdalenae management. A test of the accuracy of estimating maximum sustainable harvests using current approaches illustrates that these methods can lead to erroneous conclusions. / The results of this study are used to suggest improvements for approaches to assessing the impacts of NTFP harvest, for combining traditional ecological knowledge and science in management plans, and for using participatory ecological and ethnoecological research to promote conservation.

The wide utilization and popularity of medicinal plants in African Traditional Medicine (ATM) has been recognized and attributed to the effectiveness, affordability and accessibility of these medicinal plants. However, the extensive exploitation of medicinal plants has exacerbated the strain on the wild populations. In vitro propagation/micropropagation is an effective method which allows for mass production or multiplication of pathogen-free plants that are morphologically and genetically identical to the parent plant. In addition, the technique is contributing to the understanding of metabolic pathways and regulating the production of plant secondary products. Eucomis autumnalis (Mill.) Chitt. subspecies autumnalis (Hyacinthaceae) is a valuable medicinal species in ATM and commonly traded in the urban street markets of South Africa. Currently, the conservation status of this species has not been evaluated. However, as with most bulbous plants, the wild population is continuously under threat due to over-harvesting and habitat loss via various anthropogenic factors. Thus, in vitro propagation is a viable means of ensuring conservation of the plant species. However, mass propagation of medicinal plants should be accompanied with increased secondary metabolite production to guarantee their therapeutic efficacy. Therefore, the current study was aimed at understanding the different factors that affect the growth and secondary metabolite production in micropropagated E. autumnalis subspecies autumnalis. The influence of the type of gelling agent (gelrite versus agar) and source of initial/primary explant source (LDL = leaf explant derived from primary leaf regenerants and LDB = leaf explant derived from primary bulb regenerants) were evaluated. Gelrite-solidified medium significantly improved shoot proliferation when compared to the use of agar as a solidifying medium. In contrast, quantified phytochemicals such as flavonoids and phenolics were more enhanced in agar-supplemented media. On the basis of the explant source, shoot proliferation and secondary metabolites in regenerants from LDB were similar to those from LDL in most cases. Overall, the type of gelling agents and primary explant source individually or/and interactively significantly influenced the growth parameters as well as the production of iridoid, condensed tannin, flavonoid and phenolic content. The influence of different types of plant growth regulators (PGRs) on growth, phytochemical and antioxidant properties were evaluated. The PGRs were BA (benzyladenine); mT (meta-topolin); mTTHP [meta-topolin tetrahydropyran-2-yl or 6-(3-hydroxybenzylamino)-9-tetrahydropyran-2-ylpurine]; MemT [meta-methoxytopolin or 6-(3-methoxybenzylamino)purine]; MemTTHP [meta-methoxy 9-tetrahydropyran-2-yl topolin or 2-[6-(3-Methoxybenzylamino)-9-(tetrahydropyran-2-yl)purine] and NAA (α-naphthalene acetic acid). Five cytokinins (CKs) at 2 μM in combination with varying (0, 2.5, 5, 10, 15 μM) concentrations of NAA were tested. After 10 weeks of in vitro growth, the regenerants were acclimatized in the greenhouse for four months. Growth, phytochemical content and antioxidant activity of in vitro regenerants and ex vitro-acclimatized plants were evaluated. The highest number of shoots (approximately 9 shoots/explant) were observed with 15 μM NAA alone or with BA treatment. Acclimatized plants derived from the 15 μM NAA treatment had the highest number of roots, largest leaf area and widest bulb diameter. While applied PGRs increased the iridoids and condensed tannins in the in vitro regenerants, total phenolics and flavonoids were higher in the PGR-free treatment. In contrast to the PGR-free regenerants, 5 μM NAA and 2 μM BA treatments produced the highest antioxidant activity in the DPPH (55%) and beta-carotene (87%) test systems, respectively. A remarkable carry-over effect of the PGRs was noticeable on the phytochemical levels and antioxidant activity of the 4-month-old plants. In addition to the development of an optimized micropropagation protocol, manipulating the type and concentration of applied PGRs may serve as an alternative approach to regulate phytochemical production in Eucomis autumnalis subspecies autumnalis. The influence of smoke-water (SW), karrikinolide (KAR1) and CK analogues (PI-55 = 6-(2-hydroxy-3-methylbenzylamino)purine and INCYDE= inhibitor of cytokinin dehydrogenase or 2-chloro-6-(3-methoxyphenyl)aminopurine) individually or in combination with some selected PGRs [BA (4 μM), NAA (5 μM) and both] for in vitro propagated E. autumnalis subspecies autumnalis was evaluated. While these compounds had no significant stimulatory effect on shoot proliferation, they influenced root length at varying concentrations and when interacted with applied PGRs. The longest roots were observed in SW (1:1500), PI-55 and INCYDE (0.01 μM) treatments. There was an increase in the concentration of quantified phytochemicals (especially condensed tannins, flavonoids and phenolics) with the use of these compounds alone or when combined with PGRs. In the presence of BA, an increase in the concentration of PI-55 significantly enhanced the condensed tannin, flavonoid and phenolic contents in the regenerants. Both phenolic and flavonoid content in E. autumnalis subspecies autumnalis were significantly enhanced with 0.01 μM INCYDE. Condensed tannins was about 8-fold higher in 10-7 M KAR1 with BA and NAA treatment when compared to the control. To some varying degree, the effect of the tested compounds on the antioxidant activity of the in vitro regenerants was also noticeable. In most cases, there was no direct relationship between the level of phytochemicals and antioxidant activity recorded. The current findings indicate the array of physiological processes influenced by SW and KAR1 during micropropagation. In addition, targeting or manipulation of phytohormone metabolic pathways using CK analogues demonstrated some noteworthy effects. Perhaps, it may offer other potential practical applications in plant biotechnology and agriculture. Thus, more studies such as quantification of endogenous hormones and identification of specific phytochemicals responsible for the bioactivity in this species will provide better insights on the mechanism of action for CK analogues as well as SW and KAR1. / M. Sc. University of KwaZulu-Natal, Durban 2014.

This thesis investigates the phytochemistry and pharmacology of two neotropical plants used traditionally to treat anxiety and stress, Souroubea sympetala (Marcgraviaceae) and Piper amalago (Piperaceae). A method of phytochemical analysis was developed to characterize S. sympetala extracts, identifying and quantifying four triterpenes, which were present in higher amounts in bark as compared to leaf. Subsequently, a standardized supercritical CO2 extraction procedure for S. sympetala was developed and compared favourably with conventional extraction methods in terms of its anxiety-reducing effects in a behavioural assay of anxiety and content of the active principle, betulinic acid (BA). All of these materials demonstrated anxiolytic properties. The pharmacological mode of action of S. sympetala raw plant, extracts and isolated active principle were examined in rodent behavioural models of anxiety. The extracts were shown to have affinity for the γ-amino butyric acid (GABA)a benzodiazepine (GABAa- BZD) receptor of the central nervous system in vitro, in a competitive binding assay. Pre-treatment of animals with the GABAa-BZD antagonist flumazenil, followed by plant extract and pure compound extinguished the anxiety-reducing effect, demonstrating that S. sympetala and BA act at the GABAa- BZD receptor in vivo. The effect of S. sympetala in stressed animals, specifically its cortisol-lowering ability was investigated in vitro and in vivo in rainbow trout. Both leaf extract and BA significantly lowered cortisol in response to an adrenocorticotropic hormone (ACTH) challenge in vitro and a standardized net restraint assay in vivo. The anxiety-reducing effect of P. amalago was examined and the bioactive principle identified by bioassay-guided fractionation. P. amalago extract significantly reduced anxiety-like behaviour in rats and demonstrated affinity for the GABAa-BZD receptor in vitro. The bioactive molecule was determined to be a furofuran lignan. Together these results provide a pharmacological basis for the traditional use of S. sympetala and P. amalago to treat anxiety and elucidate their mode of action and active principles. S. sympetala is now thoroughly characterized and represents an excellent candidate plant for development as a natural health product.

Thesis (M.A.)--University of Hawaii at Manoa, 2004. / Includes bibliographical references (leaves 78-85). / vii, 85 leaves, bound 29 cm

Thesis (Ph. D., Arid Lands Resource Sciences)--University of Arizona, 1983. / Includes bibliographical references (leaves 218-232).

Originally presented as the author's Thesis (doctoral)--University of Basel, 1990. / Includes bibliographical references (p. 327-336).

Thesis (Ph.D.) - Carleton University, 2007. / Includes bibliographical references (p. 129-156). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 137-149). Also available on the Internet.

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 355-397). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 137-149). Also available on the Internet.