Leaders: Chris Stokes, CSIRO Sustainable Ecosystems, Townsville

Dick Williams, CSIRO Sustainable Ecosystems, Darwin

Full title: Understanding the impacts of disturbance on woodland dynamics and carbon cycling to improve savanna management and health

Project 1.1.4

Summary | Rationale | Project Objectives | Project Outcomes | Outputs | Project Team | More information |

Sampling for root biomass in Katherine

Rationale Appropriate management of woodlands is essential for both sustainable production and landscape health. In some areas of the savannas, woodlands are declining due to tree clearing and overuse of fire while in other areas, overgrazing and suppression of fire is leading to woodland thickening. Increasing carbon dioxide concentrations in the atmosphere have also been linked to woodland thickening in savannas. An improved understanding of woodland dynamics in response to disturbance is necessary so that sound management recommendations can be developed. Management of the woodland and grassy layer is also important for carbon cycling as the tropical savannas account for about one third of Australia’s terrestrial carbon stores and they offer significant potential as a carbon sink to offset greenhouse gas emissions. The information and understanding developed in this project will contribute to healthy landscapes by providing new indicators of health and will improve predictive models of landscape function ( Key Result Area 1 – Healthy Landscapes ). By providing a better understanding of soil carbon dynamics in response to disturbance, management strategies for fire and grazing in savannas can be refined and improved ( Key Result Area 2 Sustainable Management Systems ). Information on carbon storage and sequestration will be useful in developing policy and management options for managing Australia's greenhouse gas emissions ( Key Result Areas 2, and 3, Viable and Socially Desirable Regions ).

Summary

This project aims to quantify carbon stocks and carbon cycling in northern Australian tropical savannas, and to determine how these are influenced by grazing, fire, tree clearing and climate change. This will be achieved by a mix of allometric, experimental, remote sensing and modelling activities across northern Australia.

This research is of national and international significance, because savannas, which already account for 33% of Australia’s terrestrial carbon, may offer significant potential as a (tradable) carbon sink to offset greenhouse gas emissions; and managing carbon storage and cycling is an important aspect of maintaining healthy ecosystem function.

Grazing management, clearing, fire and climate change can significantly alter the amount of carbon stored in tropical savannas so it is important that we quantify how these disturbances affect carbon dynamics under different scenarios and determine the management implications for ecosystem health and carbon sequestration.

This project will provide estimates of carbon stores and modeled  fluxes at regional scales. We can then assess the influence of land use on these stocks and flows, using a combination of field and modeling studies. The project is linked closely to the CRC for Greenhouse Accounting.

Objectives

1. Determine the stocks of carbon in savannas, and how carbon is distributed spatially
2. Develop methods to estimate carbon stocks at enterprise and regional scales
3. Determine the influence of land use (grazing, fire, clearing, thickening) and climate change on carbon storage
4. Assess the potential for the tropical savannas to contribute to the emerging carbon economy

Outcomes

1. Integration of TS–CRC activities with research priorities of key stakeholders in the field of Carbon Accounting such as the Australian Greenhouse Office and CRC for Greenhouse Accounting, and the NT Government Greenhouse Unit
2. Integration of previous and current flux and elevated CO ₂ data into more useable form, such as regionally calibrated models
3. Refined and agreed-to protocols for estimating carbon stocks and fluxes at national scales
4. Following from 3, improved ability of land managers to account for carbon in their land management decisions;
5. National and international recognition of the potential importance of savannas as carbon sinks; and
6. Greater sequestration of carbon by savannas as a consequence of improved land management.

7. Outputs

   The principal deliverables from this project include: 

8. Regression models relating above- and below-ground biomass to tree size and species;
9. Measures of tree population structure that predict carbon stocks, and that act as input to the FLAMES and other savanna dynamics models;
10. Scaling products that quantify carbon stocks and their distribution in semi-arid savanna lands;
11. Estimates of carbon sequestration potential of tropical savannas in response to variation in grazing, fire and climate change; and
12. Models predicting the impacts of fire, grazing and climate change on carbon stocks (vegetation and soil) in semi-arid savannas.

Project Team

Dick Williams, CSIRO SE
Garry Cook, CSIRO SE
Lindsay Hutley, CDU
Adam Liedloff, CSIRO SE
Robert Eager, CSIRO SE
Andrew Ash, CSIRO SE
Joe Holtum, JCU
Chris Stokes, CSIRO SE
Mke Whiting, CSIRO SE