Microbial ecology of the Sydney Basin Temperate Highland Peat Swamps on Sandstone

The Temperate Highland Peat Swamps on Sandstone (THPSS) of the Sydney Basin are listed as endangered ecosystems, yet they continue to suffer habitat losses and degradation from anthropogenic pressures. Despite ongoing efforts to restore and better protect these swamps, they remain poorly understood, potentially hindering the effectiveness of management efforts. Vital to overall ecosystem function and the provision of services for human and environmental benefit is the microbial component of wetland/peatland ecosystems. Microbes are responsible biogeochemical cycling including the processes of carbon and nutrient cycling. Essentially, microbes control the bioavailability, export and sequestration of the elements fundamental for ecosystem function, thereby impacting peat formation and storage, primary production rates, greenhouse gas emissions and downstream water quality. Regardless of this importance, the microbial ecology of THPSS had not yet been studied. The aim of this thesis is to characterise the structure and function of microbial communities in THPSS to support improved management for the preservation of these ecosystems. To address this aim, a series of studies were undertaken to reveal the structure of microbial communities and the environmental factors that influence them, with specific emphasis on two key disturbances: fire and urbanisation. Results revealed both resilience and sensitivity of these systems. THPSS were resilient to a hazard reduction burn. Microbial communities and sediment properties in burnt swamps were similar to pre burn conditions and control swamps one year after the fire. If hazard reduction burns prevent more intense and catastrophic burns, as they are intended to, they may be helpful in maintaining the integrity of THPSS microbial community. THPSS within urbanised catchments, however, were sensitive to the ongoing urban disturbance. Microbial community composition, gene expression and abundances differed between swamps affected and unaffected (or minimally affected) by urbanisation. Linked to catchment urbanisation was elevated pH, which was also identified to be a significant influence on microbial community composition. Employing strategies to maintain naturally acidic conditions in urbanised catchments may help maintain the function of microbial communities in THPSS. Taxonomic analysis of these differences revealed catchment urbanisation was altering microbial function and was resulting in a shift from oligotrophic to copiotrophic taxa. Ratios of taxa that represent these different trophic life strategies have been suggested as microbial indicators for ecological assessment, results from this thesis indicate this may be a useful tool for assessing THPSS ecosystem health, and restoration success. Together, this body of work supports and adds to the understanding of THPSS and peatlands globally. In particular, it has highlights the effects of little studied consequences of urbanisation and fire disturbance to peatland microbial systems -- abstract.