A Methodology for Modelling Canopy Structure: An Exploratory Analysis in the Tall Wet Eucalypt Forests of Southern Tasmania

A ground-based methodology is presented for spatially modelling forest canopy structure. Field measurements and allometric relationships are used to predict the profiles of free-growing tree crowns on the basis of stem diameter at breast height (dbh). These profiles are incorporated into three-dimensional canopy models using AutoCAD™ technical drawing software and field data describing the genus, dbh and relative positions of all trees greater than 10 cm dbh; critically, our models account for the effects of competition for light between neighbouring crowns. By horizontally partitioning the models, the presence of distinct strata and the dominant genera associated with each stratum can be identified. Our methodology is applicable to other forest ecosystems as a research tool for investigating changes in vertical structure, and for calibrating remote sensing technologies in order to map and monitor canopy structural variation across forested landscapes

Environmental DNA detection of the giant freshwater crayfish (Astacopsis gouldi)

The giant freshwater crayfish, Astacopsis gouldi Clark, 1936, is an endangered endemic freshwater species native to Northern Tasmania. Habitat loss, fishing pressure, and climate change have been identified as threatening processes. The Australian government approved a recovery plan for A. gouldi in 2017 that requires routine population surveys to assess the impact of ongoing threats and recovery actions. We developed a novel species-specific probe-based assay targeting a 219 bp fragment in the Cytochrome Oxidase 1 gene region to detect traces of A. gouldi DNA in environmental samples as a cost-effective, sensitive, and non-invasive surveillance method to assess the presence of this endangered species. We tested assay specificity against ten crayfish species commonly found in Tasmania within the Astacopsis, Cherax, Geocharax, Engaeus, and Ombrastacoides genera and determined assay sensitivity using tissue-derived genomic DNA and synthetic oligo standards designed for A. gouldi. We then tested water samples collected from aquaria and natural freshwater streams in Northern Tasmania with known occurrence of A. gouldi, as well as one site with no known A. gouldi occurrence. The probe-based assay designed in this study successfully detected A. gouldi DNA and eDNA with a 10 copies/µl limit of detection and showed no amplification of non-targeted co-existing crayfish species. We successfully detected the presence of A. gouldi eDNA in water samples from six sites with known occurrences of the species. There was no detection from the negative site. This study validates the use of eDNA-based detection of A. gouldi by real-time PCR as a non-invasive monitoring tool to assist field monitoring, assessment, and complement ongoing recovery actions to protect habitable ecosystems of A. gouldi

Patterns in the phenology of four plant species across subantarctic islands during the 2003/04 summer: implication for climate change

Communication oral

Patterns in the phenology of four plant species across subantarctic islands during the 2003/04 summer: implication for climate change

Communication oral