This layer was produced by the Organic Soils Mapping (OSM) project, a project undertaken by DPIPWE Natural Values Conservation Branch between 2019 and 2021. This project received grant funding from the Australian Government through the Australian Heritage Grants Program, funding from 2017 Tasmanian Bushfire Mitigation fund and The Tasmanian Wilderness World Heritage Area fund. This project has used existing (legacy) data from previous Tasmanian land resource assessment studies, spatial data sets, expert desktop inputs, and newly captured site data from the AHG grant project activities. This project has collated these data to produce this and a further 6 spatial layers that predict the likely distribution and characteristics of Organic Soils in Tasmania. The project was focused on the Tasmanian Wilderness World Heritage Area (TWWHA), with modelling applied state-wide to assist in organic soil identification elsewhere. The Organic Soil Mapping was undertaken to specifically identify organic soil extent in the TWWHA and to increases the understanding of the organic soil landscapes and characteristics in greater Tasmania. Organic soil areas are recognised globally as ecologically significant. These landscapes support a diverse range of ecosystems. They also provide and control ecosystem services/processes and provide highly valued carbon and water storage functions. These project outputs aim to improve and assist conservation and management of these important soil landscapes. This point dataset has been collated from a combination of legacy and contemporary land resource studies and is designed to assist land managers see where actual on the ground works and assessment activities within likely organic soil areas which have confirmed the presence or absence of organic soils. Organic soils sites for the purpose of this work are defined as soil description locations with any surface Organic Materials deeper than 5cm that could constitute as a fuel in a fire situation. These soils differ from the Australian Soil Classification 3rd Edition (ASC) definition of ORGANOSOL and this term should be avoided when referring to these sites. These sites include soils from a range of ASC Soil Orders including Organosol, Hydrosol, Podosols and Tenosol that display a dominantly peaty surface layer or have organic materials (>20cm) in the uppermost surface soil layers.

Position Accuracy: Field site grid references have been obtained from handheld GPS with a 5-10m positional accuracy. Legacy information obtained from older studies have positional accuracy that could range up to 100m and further assessment may be required to verify actual site location. Care should be taken when interpretation these legacy information points. Logical Consistency: All Sites are labelled with information detailing; if they are an Organic Soil or Not an Organic Soil -Y for Yes and N for No. Additional information regarding the origin (source) of the data, data custodian, and Field describer/author are listed together with the site location in AMG format and linked to associated field descriptions and laboratory information in PDF format, where information is available. No duplicates occur but in some areas some site locations occur very close to each other (less than 10m apart) which has been dictated by the original methodology and purpose of the related legacy project or research methodology. Completeness: Additional: Component layers are available upon request. Statement This point dataset has been collated from a combination of legacy and contemporary land resource studies and is designed to assist land managers see where actual on the ground works and assessment activities within likely organic soil areas which have confirmed the presence or absence of organic soils. Sites undertaken by the Organic Soil Mapping project have used the Australian Soil and Land Survey Field Handbook (https://www.soilscienceaustralia.org.au/about/what-we-do/standards/). and Australian Soil Classification (third edition) (https://www.soilscienceaustralia.org.au/about/what-we-do/standards/) to describe and classify field data. This dataset is designed to be used in conjunction with the associated Modelled Presence-Absence Organic Soil Extent map and related spatial data layers created by the Organic Soil Mapping Project (see information below). Modelled Presence-Absence Organic Soil Extent Map: This mapping used a combination of 30m resolution modelling (Digital Soil Mapping (DSM)), with relevant features from TASVEG, legacy soil mapping and wetlands datasets as masks. A DSM approach was used due to the sparse and limited nature field data due to remote and difficult access. DSM involves using soil site data, intersected with a range of spatial environmental predictor datasets (covariates) to develop a series of landscape models, showing the variation in various soil properties between calibration points through interpolation and extrapolation. OSM products include extent and likelihood, depth, drainage, humification (amount of decomposition of organic matter), site data, and a map combining the preceding classified characteristics. The presence-absence organic soil extent map was developed using a binary calibration set of site data (1 = Organic Soil Presence, 0 = Organic Soil Absence) from the newly collected data, and any legacy data points classed as an Organosol (Australian Soil Classification) or containing an organic or peat surface layer(s) . Expert desktop digitising was undertaken identifying sites highly likely to be non-organic, mainly targeting mountainous bare-earth ridge tops in access-constrained areas, Categorical modelling was initially tested using a decision Tree (See5) approach, however, better results were used when modelling the presence-absence data as a continuous (1 to 0) index, where the modelled surface shows values closer to 1 as having a higher likelihood of being organic (i.e. meeting all the environmental conditions that indicate the presence of an organic soil). This approach allows organic soil area to be better classified by expert review, where; 0.9 - 1 High Likelihood of Organic Soil 0.7 - 0.9 Likely Organic Soil 0.5 - 0.7 Potentially Organic Soil 0 - 0.5 Unlikely to be Organic Soil Further reading: Kidd, D., Webb, M., Malone, B., Minasny, B., McBratney, A., 2015a. 80-metre Resolution 3D Soil Attribute Maps for Tasmania, Australia. Soil Research; Kidd, D.B., Malone, B.P., McBratney, A.B., Minasny, B., Webb, M.A., 2014b. Digital mapping of a soil drainage index for irrigated enterprise suitability in Tasmania, Australia. Soil Research 52, 107-119;