Pathogen driven change in species-diverse woodlands of the Southwest Australian Floristic Region: A hybrid ecosystem in a Global Biodiversity Hotspot

Carly Bishop (2012). Pathogen driven change in species-diverse woodlands of the Southwest Australian Floristic Region: A hybrid ecosystem in a Global Biodiversity Hotspot PhD Thesis, School of Agriculture and Food Sciences, The University of Queensland.

Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
s3359319_phd_abstract.pdf phd abstract application/pdf 260.52KB 0
s3359319_phd_thesis_FINAL.pdf phd thesis FINAL application/pdf 2.54MB 37
Author Carly Bishop
Thesis Title Pathogen driven change in species-diverse woodlands of the Southwest Australian Floristic Region: A hybrid ecosystem in a Global Biodiversity Hotspot
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
Publication date 2012-06
Thesis type PhD Thesis
Supervisor Dr Grant Wardell-Johnson
Total pages 156
Total colour pages 15
Total black and white pages 141
Language eng
Subjects 050102 Ecosystem Function
050103 Invasive Species Ecology
060202 Community Ecology(excl. Invasive Species Ecology)
Abstract/Summary Human-induced change in natural environments is occurring at unprecedented rates over ecologically brief periods of time. The consequences of such disturbance has been documented in both terrestrial and marine habitats with much focus on disturbance events such as extreme weather events (hurricanes, cyclones etc.), agriculture, altered fire regimes, weeds and climate change. Pathogens are increasingly being recognised as powerful agents of change, though documentation is limited and often restricted to species-level changes. Inextricably linked to the direct changes in species composition are the indirect effects of pathogens on community structure and ecosystem function. Traditional species-based studies looking at pathogen-induced change focus on specific and somewhat one-dimensional shifts in species richness, species cover and un-standardised diversity indices. This project was developed to explore the impact of pathogen disturbance beyond species-level changes using a structured and comprehensive approach that integrates current ecological theories. This PhD is part of a larger ARC linkage project titled 'Towards a Landscape Conservation Culture - broadening the spatio-temporal scope of ecological studies to anticipate change in Australian forested ecosystems'. It aims to explore questions regarding biodiversity management using an integrated landscape-level approach to conservation which looks beyond individual species. This is because the performance and persistence of an ecosystem is dependent upon the complexity of relationships between different ecosystem components at a range of spatial scales beyond the species-level. Through integrating and utilising current ecological theory and frameworks, this thesis links concepts and methods in community ecology to explore disturbance and change. This link is often inadequate in ecological literature and requires bridging through application and testing of theory in field situations or novel research. The practical integration and application of Resilience and Novel Ecosystem theory, forms the basis of the thesis and provides an alternate view of disturbance beyond species-level shifts. Resilience theory suggests that changes in composition and structure lead to an irreversible regime shift. This will be used as a basis to describe pathogen impacts and as criteria for determining if a novel or hybrid ecosystems results. Through this integration I describe changes occurring across spatial scales to provide a comprehensive account of disturbance in a forest ecosystem. I use the introduction of forest pathogen Phytophthora cinnamomi into Banksia attenuata woodlands as a case study. Banksia attenuata woodlands in the high rainfall zone of the Southwest Australian Floristic Region are highly susceptible to P. cinnamomi infestation. These woodlands contain a substantial suite of pathogen-susceptible species and are found in low lying areas of the landscape in prime position for pathogen infestation by overland water flow. Due to these factors and obvious disease expression, these Banksia woodlands were chosen for investigation. Using resilience theory as a framework I begin by describing pathogen-induced shifts in species composition and vegetation structure as a basis for further enquiry into shifts in plant functional traits. Using a chronosequence of disease expression replicated across the landscape, I identify changes in species dominance and associated shifts in stand variables (canopy cover, leaf litter and basal area). I also apply uni-variate and multivariate diversity indices that identify change at both the species and community-level. I continue by describing shifts in plant functional trait composition with deduced links to ecosystem function. These shifts in addition to the changes in species dominance and stand variables are then used to determine if a novel or hybrid ecosystem has resulted from pathogen infestation. This thesis demonstrates that that although Banksia attenuata woodlands have undergone an irreversible shift in identity (species dominance, beta diversity, stand variables, plant functional trait composition) some original features have been retained including species richness, species diversity and functional diversity. For these reasons, the post-pathogen community identifies as a hybrid ecosystem that is equally speciose despite other substantial pathogen-induced shifts. Following infestation, Banksia attenuata woodlands are unlikely to return to their previous state due to changes in site microclimate associated with the substantial shifts in species dominance and related variables.
Keyword disturbance
ecosystem function
hybrid ecosystems
novel ecosystems
Phytophthora cinnamomi
plant functional trait
regime shift
Additional Notes Colour pages: 1, 20, 21, 33, 34, 38, 39, 42, 46, 48, 112, 116, 119, 127, 128. Landscape: page 26

Citation counts: Google Scholar Search Google Scholar
Created: Fri, 08 Jun 2012, 15:50:01 EST by Ms Carly Bishop on behalf of Library - Information Access Service