Ecology and conservation gentics of the rare and threatened hammer orchid Drakaea elastica

    Research output: ThesisDoctoral Thesis

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    Abstract

    [Truncated] Highly specific ecological interactions can pose significant conservation challenges, as practitioners require an intimate knowledge of all species involved. Orchids are frequently dependent on both specialised pollinator and mycorrhizal interactions. When combined with their tendency to exist in naturally patchy populations they may be particularly susceptible to disturbance. The rare and threatened orchid, Drakaea elastica is endemic to southwestern Australia and is the focus of ongoing conservation programs. As a consequence of extensive land clearing across its range the majority of known plants are restricted to two regions. Drakaea elastica is pollinated by male Zaspilothynnus gilesi thynnine wasps that it lures to the flower by sexual deception. The goal of this study was to investigate the habitat requirements, pollination ecology and population genetic structure of D. elastica to inform in situ conservation and guide future reintroduction and habitat restoration programs.

    A major limitation to plant recruitment is the availability of suitable microsites for germination and growth. The structural microhabitat requirements of adult D. elastica plants were investigated by comparing occupied microsites between regions and occupied to random microsites within regions. Although there were significant regional differences in median values for some microhabitat variables, the differences between occupied and random microsites were similar for both regions. This analysis revealed that D. elastica requires open microsites with patches of bare sand, sparse understorey and moderate canopy cover. The observed regional differences in microhabitat variables may be a result of differing groundwater tables. The requirement for open sandy microsites with low litter and shrub cover may be linked to the competitive performance of the mycorrhizal endophyte, or due to the detrimental effects of shading of adult plants.

    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2013

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