Organic Soils Humification Map

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 show (presence /absence sites) and 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. The mapping was performed using a combination of 30m resolution modelling (Digital Soil Mapping (DSM)), expert digitising, with TASVEG, soil mapping and wetlands datasets as masks. A DSM approach was chosen due to the sparse and limited nature of existing and new field data due to the 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 (Kidd et al 2015). A similar process was used to create e a map of OSM humification as a continuous index, where values correspond to the Australian Soil and Land Survey Field Handbook texture classes (https://www.soilscienceaustralia.org.au/about/what-we-do/standards/).