The costs of reforestation: a spatial model of the costs of establishing environmental and carbon plantings

Reforestation presents a potentially important tool for carbon abatement and reducing the impact of climate change and may also provide valuable biodiversity benefits. However, the economic returns are critical in determining whether it will be a viable land use and this is highly sensitive to assumptions around upfront establishment cost. Few studies have examined the spatial variability in establishment costs or developed spatially explicit layers that estimate these costs. Here we developed a model to predict the spatially explicit costs of establishment of monoculture tree plantations for carbon sequestration (or carbon plantings) and mixed species plantations for carbon sequestration and biodiversity benefits (or environmental plantings). Within this model we parameterised three separate methods of establishing revegetation; manual planting of tubestock, mechanical planting of tubestock and direct seeding. A decision tree was used to select between the different establishment methods based on soil and terrain parameters. We applied this model to a case study across the intensive agricultural districts of Australia. We populated the model with spatially explicit cost elements from literature and interviews with industry practitioners across Australia. For the case study, 3206km 2 of carbon plantings were allocated to manual tubestock establishment and 903,127km 2 were allocated to mechanical tubestock establishment with cost estimates ranging from $631774ha -1 to $6396ha -1 . For environmental plantings, 326,512km 2 were allocated to direct seeding, 3206km 2 were allocated to manual tubestock and 576,615km 2 were allocated to mechanical tubestock establishment with costs ranging from $1703ha -1 to $9097ha -1 . These layers present an increasingly important tool for planning and policy development particularly for decision making around complex issues of land use and climate change.