Project Leader: Dr John Ludwig, CSIRO Wildlife & Ecology, Darwin

Project 4.3.4

Summary | Progress | Outputs | Project integration | Future directions | Publications | Project team | More Information |

Summary

The primary aim of this project was to integrate the new knowledge gained from the TS-CRC's research projects with existing knowledge about savannas.

Computer simulation models were the main tools for integrating these elements. After verification and validation, these models are used to predict how different land-use practices (burning, clearing, grazing) affect the functioning and health of tropical savannas. These impacts are being modelled at range of spatial scales from local landscapes to across regions using different models designed for application at these scales.

At the local landscape scale (e.g., hillslope and paddock), the Savanna model (version 4b) was used to address the potential for woody thickening in savanna pastures in the Victoria River District, and to predict the best trade-off between fire and grazing so that fire can be used to manage this thickening. Also at this scale, the Flames model was used to explore how savanna tree populations may change with different fire regimes in the long-term.

At the enterprise or pastoral property scale, the Arena model was used to explore how pasture productivity and composition may change with different grazing regimes in long term. Also at the property scale, the HerdGrasp model was linked to the Arena and Flames models to estimate the costs and benefits of using fire as a pastoral management tool.

At the national scale, the Aussie GRASS model was used to predict fuel loads (forage production), grass curing states and wildfire risks across savanna regions (e.g. the Gulf (NT) and Kimberley, WA).

All these models predict how savanna landscapes may change with different fire and grazing regimes, thereby serving as useful tools to help land managers maintain and improve savanna health into the future.

Progress

This project integrated results from a number of different TS-CRC projects that are improving our understanding of how healthy landscapes function over a range of spatial and temporal scales:

• The Savanna model 4b was used to address the potential for woody thickening and spread in paddocks typically found in the VRD, and how grazing and fire can be used to control this thickening. This modelling was done in collaboration with Dr Mike Coughenour, from Colorado State University, who developed Savanna 4b. A paper describing this modelling study was prepared for the MODSIM 2001 Conference.
• The Flames model, developed by Garry Cook and Adam Liedloff, was used to explore long-term climatic trends in savanna tree populations, and how these populations are likely to respond to different fire regimes. A paper describing these trends was also written for MODSIM 2001.
• The Arena model, developed by Matthias Boer and Mark Stafford Smith, uses a plant functional approach to explore long-term competition in grazed landscapes in response to different management regimes and environmental factors.
• Arena, Flames and the Grasp pasture production model were linked to a whole property economics model to investigate the long-term ecological and economic impact of different fire regimes on a typical pastoral property located in the tropical savannas. The costs and benefits of using prescribed fires and controlling wildfires are included in this modelling study, which involves collaboration between modellers.
• Aussie GRASS modelling is being used to predict fuel loads (as grass production), grass curing states and wildfire risks across all the savanna regions of northern Australia. A final Aussie GRASS report on the NT and Kimberley region was completed.

The project is also providing savanna management options aimed to maintain production goals while conserving natural resources (vegetation, soils and biota):

• The Savanna 4b model was used to predict which combinations of fire and grazing are best to control woody thickening in savanna pastures. The best combinations provide options in guidelines for pastoralists and other savanna land managers who want to use fire to control woody thickening.
• The Flames model was used to explore the impact of different fire regimes (i.e. frequency, seasonality) on savanna tree populations. Land managers can then use those fire regimes that maintain a desired tree-grass balance.
• The Arena model was used to simulate long-term competition between different plant functional types (i.e. annual/perennial grasses, woody shrubs/trees) in response to different pasture management regimes and environmental factors. Those management regimes that maintain valuable pasture species can be used by pastoralists.
• The Aussie GRASS model was used to predict grass fuel loads, grass curing states, and fire risks across savanna regions. This information helps fire control agencies make better decisions.

Outputs

• The four key outputs, aimed at stakeholders who are responsible for monitoring and managing the environment of tropical savannas, are:
• Quantitative guidelines for monitoring particular landscape units across the savannas which are subject to land-use impacts such as grazing and burning;
• Predictive guidelines for improving land management taking into account climate fluctuations and different land-use disturbances, with a goal to achieve a sustainable productive use and a conservation of diversity on these lands;
• Evaluations on the potential robustness of different industries using lands within the tropical savannas in terms of their biological and environmental viability, especially where these lands are changing, e.g. tree thickening, due to climate and land use; and
• Timely estimates of the risk of drought or fire across the landscapes of northern Australia savannas based on predictions of green-biomass or fuel-load states. For example, a high risk of drought is associated with no or low green-biomass and a strongly negative Southern Oscillation Index (SOI). A high risk of fire is associated with high fuel loads and the late dry season.

Project integration

This project integrated with all TS-CRC projects within the two research themes, Landscape Processes and Ecosystem Management. It also linked to TS-CRC projects within the VRD Management Study, and other such management studies as they develop. Active participation by Modelling Team Collaborators will directly link this project to state, territory and national authorities and departments, and to universities.

Research findings will also feed into the Ecosystem Management and Landscape Processes themes. This will allow us to produce integrated research findings into the health and management of the savannas.

Future directions

A major challenge is to modify the Savanna 4b model so that it better suits our future needs. This model (Savanna-Au) will have a number of improved or new features, including an improved graphical display interface; GIS 'look-up' capability for soils; land units and digital elevations; an improved water infiltration and redistribution component; a new nutrient dynamics component; an expanded set of plant functional types; new fauna responses to habitat suitability functions; and new economic indicators.

Publications

Referred journal papers

Liedloff, A.C., Coughenour, M.B., Ludwig, J.A. & Dyer, R., 2001, 'Modelling the trade-off between fire and grazing in a tropical savanna landscape, northern Australia', Environment International, vol. 27, pp. (in press).

Ludwig, J.A., Coughenour, M.B., Liedloff, A.C. & Dyer, R., 2001, 'Modelling the resilience of Australian savanna systems to grazing impacts', Environment International, vol. 27, pp. (in press).

Ludwig, J.A., Eager, R.W., Liedloff, A.C., McCosker, J.C., Hannah, D., Thurgate, N.Y., Woinarski, J.C.Z., & Catterall, C.P. 2001. 'Clearing and grazing impacts on vegetation patch structures and fauna counts in eucalypt woodland, Central Queensland', Pacific Conservation Biology vol. 6, pp. 254-272.

Ludwig, J.A., Bastin, G.N., Eager, R.W., Karfs, R., Ketner, P. & Pearce, G. 2000a, 'Monitoring Australian rangeland sites using landscape function indicators and ground- and remote-based techniques', Environmental Monitoring & Assessment, vol. 64, pp. 167-178.

Ludwig, J.A., Wiens, J.A. & Tongway, D.J., 2000, 'A scaling rule for landscape patches and how it applies to conserving soil resources in tropical savannas'. Ecosystems vol. 3, pp. 84-97.

Referred book chapters

Ludwig, J.A., 2000, 'The impact of disturbances on the sustainability of tropical savanna landscapes: two predictions and three principles', in Management for Sustainable Ecosystems, eds. P. Hale, A. Petrie, D. Moloney & P. Sattler, Centre for Conservation Biology, University of Queensland, Brisbane, Australia. pp. 87-91.

Tongway, D.J. & Ludwig, J.A. 2001. 'Combating desertification', in Encyclopedia of Soil Science, ed. R. Lal, Marcel Dekker, New York, USA, pp. (in press).

Ludwig, J.A. & Tongway, D.J., 2000, 'Viewing rangelands as landscape systems', in Rangeland Desertification, eds. O. Arnalds & S. Archer, Advances in Vegetation Sciences, Vol. 19, Kluwer Academic Publishers, The Hague. pp. 39-52

Tongway, D.J. & Ludwig, J.A. 2001. 'Australian semiarid lands and savannas', Chapter 21, in Handbook of Ecological Restoration, eds. A. Davy & M. Parrow, Cambridge University Press, Cambridge, UK. pp. (in press).

Tongway, D.J. & Ludwig, J.A. 2001. Theories on the origins, maintenance, dynamics and functioning of banded landscapes. pp. (in press). IN: D. Tongway, C. Valentin, and J. Segheri (eds). Banded Vegetation patterning in Arid and Semi-arid Environments: Ecological Processes and Consequences for Management. Ecological Studies, Vol. ? Springer-Verlag, New York. USA.

Mauchamp, A., Rambal, S., Ludwig, J.A. & Tongway, D.J. 2000. Multiscale modeling of vegetation stripes. pp. (in press). IN: D. Tongway, C. Valentin, and J. Segheri (eds). Banded Vegetation patterning in Arid and Semi-arid Environments: Ecological Processes and Consequences for Management. Ecological Studies, Vol. ? Springer, New York. USA.

Published proceedings and reports

Boer, M.M & Stafford Smith, D.M.. 2000. 'Modelling the effect of utilisation and fire on plant composition in rangelands' in Papers, Australian Rangeland Society Centenary Symposium, eds. S. Nicolson & J. Noble, 21-24 August, Broken Hill, Australia. pp.148-149.

Dyer, R., Café, L., and & Craig, A. 2001. 'Australian grassland and rangeland assessment by spatial simulation (Aussie GRASS), NT & Kimberley Rangeland Sub-project', in Final Report QNR9, Submitted to Climate Variability in Agriculture Program, Queensland Department of Natural Resources and Mines, Brisbane.

Cook, G. & Liedloff, A. 2000. 'Simulating the effects of the last hundred years of fire management and rainfall variability in north Australia.', in Papers, Australian Rangeland Society Centenary Symposium, eds. S. Nicolson & J. Noble, 21-24 August, Broken Hill, Australia. pp.158-160.

Ludwig, J.A., Bastin, G.N., Eager, R.W., Liedloff, A.C., Andison, R.T. & Cobiac M. 2000. 'Recovery of vegetation on Kidman Springs: 1973-1999', in Papers, Australian Rangeland Society Centenary Symposium, eds. S. Nicolson & J. Noble, 21-24 August, Broken Hill, Australia. pp.156-157.

Bastin, G.N., Ludwig, J.A. & Eager, R.W. 2000. 'Can aerial videography indicate landscape function?', in Papers, Australian Rangeland Society Centenary Symposium, eds. S. Nicolson & J. Noble, 21-24 August, Broken Hill, Australia. pp.173-174.

Stafford Smith, M., Ash, A., & Ludwig, J.A. 2000. 'Landscape ecology stuffs up management and policy: what can we do about it?', in Papers, Australian Rangeland Society Centenary Symposium, eds. S. Nicolson & J. Noble, 21-24 August, Broken Hill, Australia. pp. 64.

Cook, G.D., Liedloff, A.C. & Edwards, A. 2000. 'Applying a stand model of savanna trees at landscape and regional scales.', in Proceedings, 4th International Conference on Integrating GIS and Environmental Modeling (GIS/EM4): Problems, Prospects and Research Needs. 2-8 September, Banff, Alberta, Canada, pp. (on CD).

Ludwig, J.A. 2000. 'The VRD management study', in Conference Proceedings, Northern Grassy Landscapes, 29-31 August, Katherine, NT, Published by Tropical Savannas CRC, Darwin, NT, Australia, pp. 52-54

Newsletters

Bastin, G.N., Ludwig, J.A., Eager, R.W., Liedloff, A.C., Andison, R.T. & Cobiac, M. 2000. 'Vegetation Recovery: Kidman Springs exclosure photos over 25 years', in Range Management Newsletter , vol. 00/2, pp. 1-5.

Project team

Dr John Ludwig, CSIRO SE
Dr Adam Liedloff, CSIRO SE
Mr Robert Eager, CSIRO SE
Mr Michael Hope, CSIRO SE
Mr Mark Smith, CSIRO SE
Mr Rodd Dyer, NTDPIF
Mr Robert Karffs, NTDPIF
Dr Wayne Hall, QCCA/NRM
Dr Dorine Bruget, QCCA/QDNRM
Ms Lisa Collett, QCCA/QNRM
Mr Robert Hassett, QCCA/QNRM