How can we grow the plantation estate and improve private native forest management in Australia? Silvopastoral systems provide a solution

Abstract

The area of plantation forest in Australia has declined by more than 10% since 2011–12 (Whittle et al. 2019; Legg et al. 2021), with possible further losses following the 2019–20 bushfires. This is despite growing demand for wood products and their known ability to capture and store carbon. The agriculture and land-use sector has an important role to play in reducing greenhouse-gas (GHG) emissions to help meet national targets and international commitments (e.g. the Paris Agreement on climate change) and limit the increase in average global temperatures to 1.5°C. Estimates by the Australian Bureau of Agricultural Resource Economics and Sciences suggest that few or no new long-rotation hardwood plantations will be established under current policy settings and economic conditions and that high land prices preclude the establishment of new plantations on modified pasture land (Whittle et al. 2019). Although some new policy initiatives to encourage plantation investment have been announced since 2019 (e.g. the federal government’s timber plantation grants worth AUD 86 million, and the Regional Investment Corporation Plantation Loans – RICPL – scheme), it will take some years before this translates into action on the ground and to the expansion of the plantation estate. Even with large-scale new plantation investment, it will still take more than 20 years before the first small sawlogs are produced, with larger logs taking 30 years. Further, the availability of timber from public native forests has been reduced since 1990 with the creation of formal and informal reserves; by 2030, the national sustainable yield in public native forests is forecast to decline to around 38% of the level reported in the 1998 reporting period (i.e. 1992–1996; Montreal Process Implementation Group for Australia and National Forest Inventory Steering Committee 2018). So, what is the potential for increasing timber production in private native forest areas? In some regions of Australia, large areas of privately owned native forest have produced timber in the past, and some – particularly in northern Australia – are subject to livestock grazing. In 2015–16, an estimated 11.8 million ha of private native forest in Queensland and 7.2 million ha of private native forest in New South Wales (NSW) were not legally restricted from wood harvesting (Montreal Process Implementation Group for Australia and National Forest Inventory Steering Committee 2018), although these numbers overestimate the area available for timber harvesting. When considering only commercially productive forest types, Lewis et al. (2020) reported approximately 2.1 million ha of potentially harvestable private native forest in southern Queensland. From a forestry perspective, however, many of these forests are degraded and in a poor productive state. For example, Lewis et al. (2020) found that private native forests in Queensland and NSW have a high proportion of small and unmerchantable trees that are growing very slowly. Decades of high-grading – that is, the selective removal of the bestquality timber trees without follow-up silvicultural treatment – have undoubtedly contributed to the high proportion of small and unmerchantable trees at many sites (Ryan and Taylor 2006; Lewis et al. 2020). The potential of private native forests to provide timber products in the future, even with improved management, is therefore limited at present, but this is not well recognised by governments, landholders and society. In addition to their role in carbon sequestration and GHG offsets, both the plantation estate and private native forests will be crucial if Australia is to meet its growing demand for timber while reducing its international ecological footprint due to imported wood products. This is even more the case because governments have announced their intention to phase out native forest harvesting on public land in Victoria, Western Australia and South East Queensland. Several measures may be needed to ensure ongoing supplies to the domestic timber industry. Silvopastoral systems (SPSs) – in either native forests or new plantations, or both – provide one such measure that is yet to be widely adopted in Australia.