Dynamics of standing dead wood and severe fire in north Australian savannas: implications for carbon management

Peter J. Whitehead; Brett P. Murphy; Jay Evans; Dominique Lynch; Cameron P. Yates; Andrew Edwards; Harry Mcdermott; Jeremy Russell-Smith

doi:10.1071/WF24081

RESEARCH ARTICLE (Open Access)

Dynamics of standing dead wood and severe fire in north Australian savannas: implications for carbon management

Peter J. Whitehead ^A ^B , Brett P. Murphy ^C , Jay Evans ^A , Dominique Lynch ^D , Cameron P. Yates ^A ^* , Andrew Edwards ^A , Harry Mcdermott ^A and Jeremy Russell-Smith ^A ^B

+ Author Affiliations

- Author Affiliations

^A Charles Darwin University, Darwin Centre for Bushfires Research, Darwin, NT 0909, Australia.

^B North Australian Indigenous Land and Sea Management Alliance, Brinkin, NT 0810, Australia.

^C Charles Darwin University, Faculty of Science and Technology, Darwin, NT 0909, Australia.

^D Northern Territory Government, Department of Environment Parks and Water Security, PO Box 496, Palmerston, NT 0831, Australia.

^* Correspondence to: cameron.yates@cdu.edu.au

International Journal of Wildland Fire 33, WF24081 https://doi.org/10.1071/WF24081

Submitted: 14 May 2024 Accepted: 20 September 2024 Published: 16 October 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution 4.0 International License (CC BY)

Abstract

Background

Many fires in north Australian savannas are severe enough to cause canopy scorch, tree death and removal of stags. Better fire management may increase carbon sequestration in trees, perhaps including stags.

Aims

To describe and analyse dynamics of stags in tropical savannas (600–1000 mm annual rainfall) in relation to fire and better understand their role in biomass sequestration.

Methods

We monitored marked populations of live and dead trees over 12 years. Statistical models describing influences on stag creation and loss are applied in stag dynamics simulations.

Key results

Immediately following severe fire, stag biomass increases acutely because many more live trees are killed than stags removed. Between severe fires, stag losses exceed tree deaths, so peaks are quite short. Many ‘new’ stags are lost (fallen or consumed) quickly.

Conclusions

Between fires, stags comprise ~7.5–8.9% of standing above-ground biomass, more under dry conditions and during recovery from severe fire or other drivers of increased tree mortality. Fire management is unlikely to increase proportions of total woody biomass in stags unless it also reduces live biomass.

Implications

Reducing frequency of severe fires can increase total carbon sequestration in dry tropical savannas. Prediction uncertainties and management risks around sequestration present daunting challenges for policy-makers and fire management practitioners.

Keywords: biomass, carbon accounting, carbon sequestration, dead wood, fire severity, fire management, savannas, stags, tree mortality.

References

Angers V, Gauthier S, Drapeau P, Jayen K, Bergeron Y (2011) Tree mortality and snag dynamics in North American boreal tree species after a wildfire: a long-term study. International Journal of Wildland Fire 20, 751-763.
| Crossref | Google Scholar |

Ansell J, Evans J, Adjumarllarl Rangers, Arafura Swamp Rangers, Djelk Rangers, Jawoyn Rangers, Mimal Rangers, Numbulwar Numburindi Rangers, Warddeken Rangers, Yirralka Rangers, Yugul Mangi Rangers (2020) Contemporary Aboriginal savanna burning projects in Arnhem Land: a regional description and analysis of the fire management aspirations of Traditional Owners. International Journal of Wildland Fire 29, 371-385.
| Crossref | Google Scholar |

Aponte C, Tolhurst KG, Bennett LT (2014) Repeated prescribed fires decrease stocks and change attributes of coarse woody debris in a temperate eucalypt forest. Ecological Applications 24, 976-989.
| Crossref | Google Scholar | PubMed |

Barber G, Edwards A, Zander KK (2023) Fire, rain and CO₂: potential drivers of tropical savanna vegetation change, with implications for carbon crediting. Fire 6, 465.
| Crossref | Google Scholar |

Bassett M, Chia EK, Leonard SW, Nimmo DG, Holland GJ, Ritchie EG, Clarke MF, Bennett AF (2015) The effects of topographic variation and the fire regime on coarse woody debris: insights from a large wildfire. Forest Ecology and Management 340, 126-134.
| Crossref | Google Scholar |

Bates D, Mächler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. Journal of Statistical Software 67, 1-48.
| Crossref | Google Scholar |

Beck U (1992) ‘Risk society: towards a new modernity.’ (Sage: London)

Bolker B (2019) Logistic regression, accounting for differences in exposure: 29 Sep 2019. RPubs by RStudio. Available at https://rpubs.com/bbolker/logregexp

Breheny P, Burchett W (2017) Visualization of regression models using visreg. The R Journal 9, 56-71.
| Crossref | Google Scholar |

Brooks ME, Kristensen K, van Benthem KJ, Magnusson A, Berg CW, Nielsen A, Skaug HJ, Mächler M, Bolker BM (2017) glmmTMB balances speed and flexibility among packages for zero-inflated generalized linear mixed modeling. The R Journal 9(2), 378-400.
| Crossref | Google Scholar |

Burnham K, Anderson D (2002) ‘Model selection and inference: a practical information-theoretic approach.’ (Springer-Verlag: New York)

Butler D, Evans M, MacIntosh A (2022) ‘Australian National University (ANU)–University of New South Wales (UNSW) ERF research team submission to the Chubb Review.’ (Australian National University and University of New South Wales: Canberra, ACT)

Chubb I, Bennett A, Gorring A, Hatfield-Dodds S (2022) ‘Independent Review of ACCUs.’ (Department of Climate Change, Energy, the Environment and Water: Canberra, ACT)

Commonwealth of Australia (2018) ‘Carbon credits (carbon farming initiative—savanna fire management—sequestration and emissions avoidance) methodology determination 2018.’ (Minister for Environment and Energy: Canberra, ACT)

Collins L, Bradstock RA, Tasker EM, Whelan RJ (2012) Can gullies preserve complex forest structure in frequently burnt landscapes? Biological Conservation 153, 177-186.
| Crossref | Google Scholar |

Cook G, Liedloff A, Eager R, Chen X, Williams R, O’Grady A, Hutley L (2005) The estimation of carbon budgets of frequently burnt tree stands in savannas of northern Australia, using allometric analysis and isotopic discrimination. Australian Journal of Botany 53, 621-630.
| Crossref | Google Scholar |

Cook GD, Liedloff AC, Meyer CP, Richards AE, Bray SG (2020) Standing dead trees contribute significantly to carbon budgets in Australian savannas. International Journal of Wildland Fire 29, 215-228.
| Crossref | Google Scholar |

Corey B, Andersen A, Legge S, Woinarski JC, Radford IJ, Perry JJ (2019) Better biodiversity accounting is needed to prevent bioperversity and maximize co-benefits from savanna burning. Conservation Letters 13, e12685.
| Crossref | Google Scholar |

Cousins S, Battles J, Sanders JE, York R (2015) Decay patterns and carbon density of standing dead trees in California mixed conifer forests. Forest Ecology and Management 353, 136-147.
| Crossref | Google Scholar |

Dunn CJ, O’Connor CD, Reilly MJ, Calkin DE, Thompson MP (2019) Spatial and temporal assessment of responder exposure to snag hazards in post-fire environments. Forest Ecology and Management 441, 202-214.
| Crossref | Google Scholar |

Edwards A, Russell-Smith J, Meyer M (2015) Contemporary fire regime risks to key ecological assets and processes in north Australian savannas. International Journal of Wildland Fire 24, 857-870.
| Crossref | Google Scholar |

Edwards AC, Russell-Smith J, Maier SW (2018) A comparison and validation of satellite-derived fire severity mapping techniques in fire prone north Australian savannas: extreme fires and tree stem mortality. Remote Sensing of Environment 206, 287-299.
| Crossref | Google Scholar |

Fei S, Morin RS, Oswalt CM, Liebhold AM (2019) Biomass losses resulting from insect and disease invasions in US forests. Proceedings of the National Academy of Sciences 116, 17371-17376.
| Crossref | Google Scholar | PubMed |

Fensham RJ (2005) Monitoring standing dead wood for carbon accounting in tropical savanna. Australian Journal of Botany 53, 631-638.
| Crossref | Google Scholar |

Fensham RJ, Fairfax RJ, Ward DP (2009) Drought-induced tree death in savanna. Global Change Biology 15, 380-387.
| Crossref | Google Scholar |

Franklin JF, Shugart HH, Harmon ME (1987) Tree death as an ecological process. BioScience 37, 550-556.
| Crossref | Google Scholar |

Gifford RM (2000) ‘Carbon contents of above-ground tissues of forest and woodland trees. National Carbon Accounting System Technical Report no. 22. September 2000.’ (CSIRO Plant Industry: Canberra, ACT)

Gillner S, Rüger N, Roloff A, Berger U (2013) Low relative growth rates predict future mortality of common beech (Fagus sylvatica L.). Forest Ecology and Management 302, 372-378.
| Crossref | Google Scholar |

Gora EM, Lucas JM, Yanoviak SP (2019a) Microbial composition and wood decomposition rates vary with microclimate from the ground to the canopy in a tropical forest. Ecosystems 22, 1206-1219.
| Crossref | Google Scholar |

Gora EM, Kneale RC, Larjavaara M, Muller-Landau HC (2019b) Dead wood necromass in a moist tropical forest: stocks, fluxes, and spatiotemporal variability. Ecosystems 22, 1189-1205.
| Crossref | Google Scholar |

Gray A, Ganey JL, Vojta SC (2012) Trends in snag populations in drought-stressed mixed-conifer and ponderosa pine forests (1997-2007). International Journal of Forestry Research 2012, 529197.
| Crossref | Google Scholar |

Hanson C (2021) ‘Smokescreen: debunking wildfire myths to save our forests and our climate.’ (University Press of Kentucky: Lexington, Kentucky, USA)

Harmon ME, Franklin JF, Swanson FJ, Solkins PJ, Gregory SV, Lattin JP, Andersen NH, Cline SP, Aumen N, Sedell JR, Lienkaemper GW, Cromack K, Cummins KW (1986) Ecology of coarse woody debris in temperate ecosystems. Advances in Ecological Research 15, 133-302.
| Crossref | Google Scholar |

Hilger AB, Shaw CH, Metsaranta JM, Kurz WA (2012) Estimation of snag carbon transfer rates by ecozone and lead species for forests in Canada. Ecological Applications 22, 2078-2090.
| Crossref | Google Scholar | PubMed |

Hutley LB, Evans BJ, Beringer J, Cook GD, Maier SW, Razon E (2013) Impacts of an extreme cyclone event on landscape-scale savanna fire, productivity and greenhouse gas emissions. Environmental Research Letters 8, 045023.
| Crossref | Google Scholar |

Kwon S, Kim S, Kim J, Kang W, Park K-H, Kim C-B, Girona MM (2021) Predicting post-fire tree mortality in a temperate pine forest, Korea. Sustainability 13, 569.
| Crossref | Google Scholar |

Law S, Eggleton P, Griffiths H, Ashton L, Parr C (2019) Suspended dead wood decomposes slowly in the tropics, with microbial decay greater than termite decay. Ecosystems 22, 1176-1188.
| Crossref | Google Scholar |

Leitold V, Morton DC, Longo M, dos-Santos MN, Keller M, Scaranello M (2018) El Niño drought increased canopy turnover in Amazon forests. New Phytologist 219, 959-971.
| Crossref | Google Scholar | PubMed |

Lindenmayer D, Zylstra P (2024) Identifying and managing disturbance-stimulated flammability in woody ecosystems. Biological Reviews 99, 699-714.
| Crossref | Google Scholar | PubMed |

Lloyd JD, Slater GL, Snyder JR (2012) The role of fire-return interval and season of burn in snag dynamics in a south Florida slash pine forest. Fire Ecology 8, 18-31.
| Crossref | Google Scholar |

Lugo AE, Scatena FN (1996) Background and catastrophic tree mortality in tropical moist, wet, and rain forests. Biotropica 28, 585-599.
| Crossref | Google Scholar |

Lynch D, Cuff N, Russell-Smith J (2015) Vegetation fuel type classification for lower rainfall savanna burning abatement projects. In ‘Carbon accounting and savanna fire management’. (Eds BP Murphy, AC Edwards, CP Meyer, J Russell-Smith) pp. 73–96. (CSIRO Publishing: Melbourne, Vic)

Murphy BP, Whitehead PJ, Evans J, Yates CP, Edwards AC, MacDermott HJ, Lynch DC, Russell-Smith J (2023) Using a demographic model to project the long-term effects of fire management on tree biomass in Australian savannas. Ecological Monographs 93, e1564.
| Crossref | Google Scholar |

National Environmental Science Program Earth Systems and Climate Change Hub. (2020) ‘Climate change in the Northern Territory: state of the science and climate change impacts.’ (NESP ESCC Hub: Aspendale, Vic)

Oberle B, Ogle K, Zanne AE, Woodall CW (2018) When a tree falls: controls on wood decay predict standing dead tree fall and new risks in changing forests. PLoS One 13, e0196712.
| Crossref | Google Scholar | PubMed |

Paul KI, Roxburgh SH (2024) A national accounting framework for fire and carbon dynamics in Australian savannas. International Journal of Wildland Fire 33, WF23104.
| Crossref | Google Scholar |

Paul KI, Roxburgh SH, Chave J, England JR, Zerihun A, Specht A, Lewis T, Bennett LT, Baker TG, Adams MA, Huxtable D, Montagu KD, Falster DS, Feller M, Sochacki S, Ritson P, Bastin G, Bartle J, Wildy D, Hobbs T, Larmour J, Waterworth R, Stewart HT, Jonson J, Forrester DI, Applegate G, Mendham D, Bradford M, O’Grady A, Green D, Sudmeyer R, Rance SJ, Turner J, Barton C, Wenk EH, Grove T, Attiwill PM, Pinkard E, Butler D, Brooksbank K, Spencer B, Snowdon P, O’Brien N, Battaglia M, Cameron DM, Hamilton S, McAuthur G, Sinclair J (2016) Testing the generality of above-ground biomass allometry across plant functional types at the continent scale. Global Change Biology 22, 2106-2124.
| Crossref | Google Scholar | PubMed |

Perry JJ, Sinclair M, Wikmunea H, Wolmby S, Martin D, Martin B (2018) The divergence of traditional Aboriginal and contemporary fire management practices on Wik traditional lands, Cape York Peninsula, Northern Australia. Ecological Management & Restoration 19, 24-31.
| Crossref | Google Scholar |

Pietsch KA, Eichenberg D, Nadrowski K, Bauhus J, Buscot F, Purahong W, Wipfler B, Wubet T, Yu MJ, Wirth C (2019) Wood decomposition is more strongly controlled by temperature than by tree species and decomposer diversity in highly species rich subtropical forests. Oikos 128, 701-715.
| Crossref | Google Scholar |

Polo JA, Hallgren SW, Leslie DM (2013) Effect of long-term understory prescribed burning on standing and down dead woody material in dry upland oak forests. Forest Ecology and Management 291, 128-135.
| Crossref | Google Scholar |

Price OF, Russell-Smith J, Watt F (2012) The influence of prescribed fire on the extent of wildfire in savanna landscapes of western Arnhem Land, Australia. International Journal of Wildland Fire 21, 297-305.
| Crossref | Google Scholar |

Pyne S, Andrews P, Laven R (1996) ‘Introduction to wildland fire.’ (Wiley: New York, NY, USA)

Russell-Smith J, Edwards AC (2006) Seasonality and fire severity in savanna landscapes of monsoonal northern Australia. International Journal of Wildland Fire 15, 541-550.
| Crossref | Google Scholar |

Russell-Smith J, Yates C, Whitehead P, Smith R, Craig R, Allan G, Thackway R, Frakes I, Cridland S, Meyer C, Gill M (2007) Bushfires ‘Down Under’: patterns and implications of contemporary Australian landscape burning. International Journal of Wildland Fire 16, 361-377.
| Crossref | Google Scholar |

Russell-Smith J, Murphy BP, Meyer CP, Cook GD, Maier S, Edwards AC, Schatz J, Brocklehurst P (2009) Improving estimates of savanna burning emissions for greenhouse accounting in northern Australia: limitations, challenges, applications. International Journal of Wildland Fire 18, 1-18.
| Crossref | Google Scholar |

Setterfield S, Rossiter-Rachor N, Hutley L, Douglas M, Williams R (2010) Turning up the heat: the impacts of Andropogon gayanus (gamba grass) invasion on fire behaviour in northern Australian savannas. Diversity and Distributions 16, 854-861.
| Crossref | Google Scholar |

Shaffer TL (2004) A unified approach to analyzing nest success. The Auk 121, 526-540.
| Crossref | Google Scholar |

Threlfall CG, Law BS, Peacock RJ (2019) Benchmarks and predictors of coarse woody debris in native forests of eastern Australia. Austral Ecology 44, 138-150.
| Crossref | Google Scholar |

Verschuren L, De Mil T, De Frenne P, Haneca K, Van Acker J, Vandekerkhove K, Van den Bulcke J (2023) Heading for a fall: the fate of old wind-thrown beech trees (Fagus sylvatica) is detectable in their growth pattern. Science of The Total Environment 903, 166148.
| Crossref | Google Scholar | PubMed |

Whitehead PJ, Russell-Smith J, Yates C (2014) Fire patterns in north Australian savannas: extending the reach of incentives for savanna fire emissions abatement. The Rangelands Journal 36, 371-388.
| Crossref | Google Scholar |

Wohling M (2009) The problem of scale in indigenous knowledge: a perspective from northern Australia. Ecology and Society 14(1),.
| Crossref | Google Scholar |

Wood S (2017) ‘Generalized additive models: an introduction with R.’ 2nd edn. (Chapman and Hall/CRC)

Wood S, Scheipl F (2020) gamm4: generalized additive mixed models using ‘mgcv’ and ‘lme4’. Available at https://rdrr.io/cran/gamm4/

Woolley L-A, Murphy BP, Radford IJ, Westaway J, Woinarski JC (2018) Cyclones, fire, and termites: the drivers of tree hollow abundance in northern Australia’s mesic tropical savanna. Forest Ecology and Management 419–420, 146-159.
| Crossref | Google Scholar |

Zhao WW, van Logtestijn RSP, van der Werf GR, van Hal JR, Cornelissen JHC (2018) Disentangling effects of key coarse woody debris fuel properties on its combustion, consumption and carbon gas emissions during experimental laboratory fire. Forest Ecology and Management 427, 275-288.
| Crossref | Google Scholar |