Ecological and genetic indicators of restoration success

    Research output: ThesisDoctoral Thesis

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    Abstract

    [Truncated] Restoration ecology is a rapidly growing science of global significance, assisting the recovery of ecosystems degraded, damaged or destroyed from human intervention and action. Increasingly, the focus is shifting beyond just restoring plant community structure to reinstating ecosystem functionality. A key process for sustainable plant communities is reproductive functionality, requiring robust pollinator services typically involving pollinators. Despite this, few restoration projects to date have explicitly assessed the restoration of pollinators. Pollinators are rarely specified in restoration targets as they are mobile and little is known about how they respond to habitat restoration, influence mating systems and reproductive success. The assumption is that once plant communities are established, pollinators and pollinator services will passively establish.
    In this thesis, ecological studies of invertebrate and vertebrate richness, pollinator abundance and behaviour together with genetic analyses of pollen dispersal, mating and genetic structure using microsatellite DNA markers were conducted in several natural and restored Banksia (Proteaceae) woodland sites on the Swan Coastal Plain of Western Australia. Located within a global biodiversity hotspot, the Southwest Australian Floristic Region contains the highest proportion of vertebrate-pollinated plant species in the world with the largest number of nectar-feeding bird and mammal species. These Banksia woodlands have undergone severe habitat destruction with urban expansion and are situated on significant deposits for sand mining that have seen post-mining ecological restoration of variable standards. This provides a model system for testing and assessing the ecological genetic consequences of restoration in a fragmented landscape. The dominant species in these woodlands, Banksia attenuata and B. menziesii, depend solely on animal-mediated pollen flow to effectively reproduce, with nectarivorous birds (honeyeaters, Meliphagidae) and flying insects as key pollinators. By focussing on these species, this thesis assesses the restoration of reproductive functionality in restored plant communities by testing: (1) the effect of restoration on the diversity, abundance and behaviour of bird and insect pollinator communities, (2) the impact of pollinator behaviour on realised pollen dispersal, genetic landscape connectivity and reproductive output in B. menziesii, (3) the successful restoration and maintenance of genetic diversity and spatial genetic structure within restored and natural B. menziesii populations, and (4) the effects of high and low diversity restoration approaches for genetic integration, connectivity and mating systems of B. attenuata. Studies were conducted within an array of natural bushland sites of differing levels of degradation and two restored sites, one with high plant species diversity and richness, and structural vegetation complexity reflective of pre-disturbance levels (high complexity), the second with low plant species diversity and richness (many non-native to the site), and vegetation structure of much lower complexity than found within predisturbance Banksia woodlands (low complexity).
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2015

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