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