Maintaining contribution to global carbon cycles

What is the carbon balance of NSW forests currently and under different scenarios?


Community concern about climate change has focused attention on the carbon cycle including the role of carbon capture by vegetation. NSW forests contribute to the global carbon cycle. Maintaining forest carbon stocks is an important indicator of sustainable forest management.

Project CC1: Carbon balance of NSW forests

The Forest Monitoring Steering Committee commissioned a team from the Mullion Group, NSW Department of Primary Industries and the CSIRO to quantify the carbon balance of NSW forests and how this may change under different policy, management and climate scenarios. Dr Robert Waterworth, a lead IPPC author and former Eureka science prize winner, led the work.

The researchers have now delivered a final report.

The findings

The outcomes of this assessment represent a significant advancement in understanding the trends in forest carbon across NSW.

The results indicate that carbon stock within NSW forests varies across the state and is subject to change due to natural disturbances (fire, drought, natural regeneration) and anthropogenic activities (land clearing, reforestation, prescribed fire and timber harvesting).

Key findings include:

  • There has been a net loss of forest carbon within NSW between 1990 and the end of 2020, estimated at around 164 Mt of carbon (excluding soil) under a ‘mid’ growth scenario.
  • The net loss is primarily driven by the 2019/2020 fire season, which resulted in significantly larger changes in forest carbon than at any other point in the preceding three decades.
  • There was a general decline in forest carbon in the 1990s, net gains in forest carbon from the mid-2000s to 2019, and a large loss of forest carbon in 2020 associated with fire events.

The authors note this project demonstrates importance of having a comprehensive forest monitoring program in place with operational systems to conduct the analysis.

The full findings and analysis are available in the final report.

Data

The report, methods and project output data can be found on the TERN Data Discovery Portal and SEED.

The approach

The researchers developed a comprehensive spatial and temporal analysis to estimate the annual forest carbon balance for NSW Forests from 1990 to 2020.

The team adapted the method, assumptions and core data sets used for the Australian Government’s National Greenhouse Gas Inventory (NGGI), except where more detailed NSW-specific data was available through the Forest Monitoring and Improvement Program. Key data inputs included forest type and extent, climate, and disturbance history.

The analysis used FLINTpro – a spatially explicit integration system – to replicate the fundamental forest growth models within the NGGI. Two main drivers of change were modelled: processes, such as forest growth; and events, such as fire and clearing.

Following delivery of initial results in mid-2021 the Commission extended the project to include additional carbon pools and more recent data on changes in forest extent and improved mapping of fire severity, including the impact of the 2019/20 wildfires.

Papers and reports