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. 2024 Nov;635(8040):898-905.
doi: 10.1038/s41586-024-08174-6. Epub 2024 Nov 13.

Biodiversity impacts of the 2019-2020 Australian megafires

Don A Driscoll  1 Kristina J Macdonald  2 Rebecca K Gibson  3 Tim S Doherty  4   5 Dale G Nimmo  6 Rachael H Nolan  7 Euan G Ritchie  2 Grant J Williamson  8 Geoffrey W Heard  9   10 Elizabeth M Tasker  11 Rohan Bilney  12 Nick Porch  2 Rachael A Collett  2 Ross A Crates  10 Alison C Hewitt  7 Elise Pendall  7 Matthias M Boer  7 Jody Gates  13 Rebecca L Boulton  14 Christopher M Mclean  15 Heidi Groffen  16 Alex C Maisey  17 Chad T Beranek  18 Shelby A Ryan  18 Alex Callen  18 Andrew J Hamer  18   19 Andrew Stauber  18 Garry J Daly  20 John Gould  18 Kaya L Klop-Toker  18 Michael J Mahony  18 Oliver W Kelly  18 Samantha L Wallace  18 Sarah E Stock  18 Christopher J Weston  21 Liubov Volkova  21 Dennis Black  17 Heloise Gibb  17 Joshua J Grubb  17 Melodie A McGeoch  17 Nick P Murphy  17 Joshua S Lee  7   22 Chris R Dickman  4 Victor J Neldner  23 Michael R Ngugi  23 Vivianna Miritis  4 Frank Köhler  24 Marc Perri  25 Andrew J Denham  11   26 Berin D E Mackenzie  11 Chris A M Reid  24 Julia T Rayment  27 Alfonsina Arriaga-Jiménez  28   29 Michael W Hewins  28 Andrew Hicks  30 Brett A Melbourne  30 Kendi F Davies  30 Matthew E Bitters  30 Grant D Linley  6 Aaron C Greenville  4 Jonathan K Webb  31 Bridget Roberts  26 Mike Letnic  22 Owen F Price  26 Zac C Walker  2 Brad R Murray  31 Elise M Verhoeven  4 Alexandria M Thomsen  22 David Keith  22 Jedda S Lemmon  32 Mark K J Ooi  22 Vanessa L Allen  32 Orsi T Decker  33 Peter T Green  17 Adnan Moussalli  34 Junn K Foon  7   24 David B Bryant  35 Ken L Walker  34 Matthew J Bruce  35 George Madani  18 Jeremy L Tscharke  36 Benjamin Wagner  37 Craig R Nitschke  37 Carl R Gosper  38 Colin J Yates  38 Rebecca Dillon  39 Sarah Barrett  40 Emma E Spencer  4 Glenda M Wardle  4 Thomas M Newsome  4 Stephanie A Pulsford  41 Anu Singh  37   42 Adam Roff  18   43 Karen J Marsh  44 Kye Mcdonald  45 Lachlan G Howell  2   18 Murraya R Lane  44 Romane H Cristescu  45 Ryan R Witt  18 Emma J Cook  41 Felicity Grant  41 Bradley S Law  46 Julian Seddon  41 Karleah K Berris  47 Ryan M Shofner  22 Mike Barth  47 Torran Welz  47 Alison Foster  48 David Hancock  48 Matthew Beitzel  41 Laura X L Tan  49 Nathan A Waddell  2 Pamela M Fallow  49 Laura Schweickle  50 Tom D Le Breton  22 Craig Dunne  51 Mikayla Green  6 Amy-Marie Gilpin  7 James M Cook  7 Sally A Power  7 Katja Hogendoorn  52 Renee Brawata  41   53 Chris J Jolly  54 Mark Tozer  11 Noushka Reiter  17   44   55 Ryan D Phillips  17   55
Affiliations

Biodiversity impacts of the 2019-2020 Australian megafires

Don A Driscoll et al. Nature. 2024 Nov.

Abstract

With large wildfires becoming more frequent1,2, we must rapidly learn how megafires impact biodiversity to prioritize mitigation and improve policy. A key challenge is to discover how interactions among fire-regime components, drought and land tenure shape wildfire impacts. The globally unprecedented3,4 2019-2020 Australian megafires burnt more than 10 million hectares5, prompting major investment in biodiversity monitoring. Collated data include responses of more than 2,000 taxa, providing an unparalleled opportunity to quantify how megafires affect biodiversity. We reveal that the largest effects on plants and animals were in areas with frequent or recent past fires and within extensively burnt areas. Areas burnt at high severity, outside protected areas or under extreme drought also had larger effects. The effects included declines and increases after fire, with the largest responses in rainforests and by mammals. Our results implicate species interactions, dispersal and extent of in situ survival as mechanisms underlying fire responses. Building wildfire resilience into these ecosystems depends on reducing fire recurrence, including with rapid wildfire suppression in areas frequently burnt. Defending wet ecosystems, expanding protected areas and considering localized drought could also contribute. While these countermeasures can help mitigate the impacts of more frequent megafires, reversing anthropogenic climate change remains the urgent broad-scale solution.

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Conflict of interest statement

Competing interests: The authors declare that some of them work for government agencies involved in forestry and implementing planned burns (Supplementary Table 8). The lead author declares that, despite the potential for government agencies to impose policy positions on staff communications (see ref. 51), scientific independence and integrity has been maintained throughout this project.

Figures

Fig. 1
Fig. 1. Study regions relative to fire extent.
ac, Maps of study regions within Australia, showing Stirling Ranges (Western Australia) (a), Kangaroo Island (South Australia) (b) and eastern Australian (c) sites, highlighting areas burnt in the 2019–2020 fire season and sites surveyed. Basemap copyright 2014 Esri. Data sources: Esri, Maxar, Earthstar Geographics and the GIS User Community. State boundaries: Australian Bureau of Statistics (July 2021–June 2026), Australian Statistical Geography Standard (ASGS) Edition 3, https://www.abs.gov.au/, accessed September 2024.
Fig. 2
Fig. 2. More extreme pre-fire disturbance led to larger increases and declines after fire.
Conceptual diagram illustrating the main finding that more extreme pre-fire disturbance and more extensive or severe fires led to both larger increases and larger declines after fire. Upper and lower rows indicate high and low disturbance relationships, respectively. Effect sizes are illustrative only.
Fig. 3
Fig. 3. Effects of wildfire on occurrence or abundance were modified by fire-regime components.
ad, Mean standardized effect sizes (±95% CIs) for fire severity (a), and main effects or interactions with fire severity for fire frequency (number of fires 1979–2019) (b); inter-fire interval (years) preceding 2019–20 fires (c); unburnt vegetation within 2.5 km (d) (see Table 1 and Extended Data Fig. 6 for high, mid and low category boundaries). Orange row labels, low-severity fire; red row labels, high-severity fire; black row labels, main effect without severity interaction. Main effects are plotted when interactions had no statistical support (P > 0.1). Left panels (black), negative mean effect size (average effect size for all effects less than 0); central panels (grey), overall mean effect sizes (mean of all negative, zero and positive effects); right panels (blue), positive mean effect sizes (average effect size for all effects greater than 0). Error bars are symmetrical but truncated at −1 and 1. Vertical dotted line at 0 is a guide to when effects differ from zero. Numbers in black within panels above each result are the number of effects contributing to each mean effect (n). Boxplots of raw data are in light grey, indicating median, 25th and 75th percentiles, with whiskers 1.5× interquartile range. Numbers in light grey below a result at panel margins indicate whisker values (left and right panels) or box margins (centre panel) that exceeded x axis limits. Predicted values consider random effects so may not align with raw data. P values for plotted results are the omnibus two-tailed test. Test F statistics (from left to right) for fire severity: F(1,41) = 7.74; F(1,41) = 0.42; F(1,26) = 10.18; fire frequency: F(3,39) = 11.3; F(3,33) = 11.78; F(3,30) = 6.41; inter-fire interval: F(2,42) = 10.28; F(2,37) = 5.44; F(2,31) = 13.35; unburnt area: F(2,22) = 19.93; F(2,29) = 1.02; F(2,21) = 9.2.
Fig. 4
Fig. 4. Pre-fire drought and tenure mediated the effects of wildfire.
ac, Mean standardized effects (±95% CI) of wildfire were modified by fire severity and its interaction with pre-fire drought (a), being in a protected area or not (b) and the proportion of protected area within 2.5 km (c). Orange row labels, low-severity fire; red row labels, high-severity fire; black row labels, main effect without severity interaction. Numbers in black within panels (n) are the number of effects contributing to each mean effect, and P values are for the plotted result. Panel layout and graphic features as in Fig. 3. Although the interaction of severity with drought for negative effects was weakly supported (a), the main effect was strongly supported (F(1,37) = 14.82, P < 0.001; Supplementary Table 1). Test F statistics (from left to right) for pre-fire drought: F(2,37) = 2.53; F(2,46) = 4.58; F(2,28) = 4.05; protected/unprotected area: F(1,44) = 3.33; F(1,46) = 0.62; F(1,31) = 8.54; extent of protected area: F(2,36) = 2.47; F(2,45) = 17.14; F(2,31) = 2.65.
Fig. 5
Fig. 5. Wildfire impacts varied across taxa and ecosystems.
a,b, Mean standardized effects (±95% CI) of wildfire on occurrence or abundance was modified by the interaction of fire severity with taxon (a) and ecosystem (b). Orange row labels, low severity fire; red row labels, high severity fire; black row labels, main effect without severity interaction. Numbers in black within panels are the number of effects contributing to each mean effect (n), and P values are for the plotted result. Panel layout and graphic features as in Fig. 3. Test F statistics (from left to right) for taxon: F(5,29) = 5.84; F(5,29) = 23.39; F(5,15) = 8.15; ecosystem: F(3,31) = 8.48; F(3,32) = 5.3; F(4,30) = 69.19.
Extended Data Fig. 1
Extended Data Fig. 1. Data extraction for calculating effect sizes.
Flow diagram illustrating how the full dataset (1) was subdivided so that effect sizes could be calculated for each taxon within each project. Each row represents a record of taxon occurrence or abundance at an individual survey site within a project. (2) represents data treatment for covariates that varied at the taxon-within-project level (broad taxon, ecosystem type). (3) represents data treatment for covariates that differed between sites within projects (e.g. drought, inter-fire interval).
Extended Data Fig. 2
Extended Data Fig. 2. How wildfire impacted occurrence or abundance was modified by study design, year, response, and region.
Mean standardised effect sizes (±95% CI) for study design (a), year (b), and main effects or interactions with fire severity for response (c), and region (d). Graphic features as for Fig. 1. P values are for the plotted result and are the omnibus two-tailed test based on an F distribution. Test statistics (from left to right) for Study design: F(1,55) = 1.09, P = 0.302; F(1,61) = 1.26, P = 0.266; F(1,40) = 0.01, P = 0.917; Year: F(1,44) = 7.83, P = 0.008; F(1,47) = 15.57, P < 0.001; F(1,33) = 0.43, P = 0.519; Response: F(1,44) = 0.13, P = 0.724; F(1,47) = 0.7, P = 0.408; F(1,24) = 20.87, P < 0.001; Region: F(2,43) = 46.66, P < 0.001; F(2,46) = 25.96, P < 0.001; F(2,26) = 5.11, P = 0.013. Unburnt-burnt designs (Unb-burn, (a)) were used for all other analyses, so represent the overall effects of the 2019–20 fires without additional covariates. Before-after (Bef-after) survey designs produced a distribution of effect sizes that was shifted to the right with smaller negative and larger positive effects compared with unburnt-burnt designs, suggesting bias associated with the drought-breaking rains after the fires (a). In the second year after the fires there was a subtle reduction in mean negative effect sizes, hinting that recovery was beginning for some taxa that declined (b). Abundance (Abund) and occurrence (Occur) responses showed very similar effect sizes, with the only exception of higher positive effect sizes for occurrence data at high severity. The small number of effects in this group precludes further separate consideration of occurrence responses (c). The most striking regional effect was for weaker positive effects in the south, particularly at high severity (d). Fire conditions differed across regions. Our data suggest a weak trend towards stronger pre-fire drought in the south (Pearson’s correlation with latitude =−0.03, t = −2.5343, df = 6239, P = 0.01). Fires that drove the world’s most extreme pyrocumulonimbus event were all in our mid and southern regions, corresponding with larger contiguous areas of high severity fire. Remote sensing data indicate that the southern parts of the study region had slower rates of vegetation recovery than in the north. These differences in pre-fire conditions, fire behaviour, and recovery rates suggest that the level of disturbance and other stressors can constrain the response of taxa which would otherwise benefit from bushfires.
Extended Data Fig. 3
Extended Data Fig. 3. Mean difference effect sizes (±95% CI).
See previous figures for details. Panels match: top left; Fig. 3, top right; Fig. 4; bottom left; Fig. 5, bottom right Extended Data Fig. 2. Mean change effect size shown for Study design with before-after data, bottom right panel. P values are for the plotted result and are the omnibus two-tailed test based on an F distribution. Top left panel test statistics (from left to right): Fire severity: F(1,41) = 4.77, P = 0.035; F(1,41) = 0.7, P = 0.407; F(1,26) = 40.63, P < 0.001; Fire frequency: F(3,39) = 11.08, P < 0.001; F(3,33) = 2.68, P = 0.063; F(3,26) = 5.6, P = 0.004; Inter-fire interval: F(2,42) = 21.74, P < 0.001; F(2,37) = 13.77, P < 0.001; F(2,25) = 54.2, P < 0.001; Unburnt area: F(2,22) = 15.7, P < 0.001; F(2,29) = 43.89, P < 0.001; F(2,21) = 1.4, P = 0.268. Top right panel test statistics (from left to right): Pre-fire drought: F(2,37) = 4.06, P = 0.025; F(2,46) = 21.77, P < 0.001; F(2,28) = 13.48, P < 0.001; P.A. or Not: F(1,39) = 2.85, P = 0.1; F(1,46) = 2.01, P = 0.163; F(1,31) = 17.26, P < 0.001; P.A. area: F(2,36) = 12.09, P < 0.001; F(2,45) = 1.35, P = 0.271; F(2,25) = 5.32, P = 0.012. Bottom left panel test statistics (from left to right): Taxon: F(5,29) = 88.71, P < 0.001; F(5,29) = 22.98, P < 0.001; F(5,15) = 19.43, P < 0.001; Ecosystem: F(3,31) = 7.6, P = 0.001; F(3,32) = 69.68, P < 0.001; F(3,21) =2.58, P = 0.081. Bottom right panel test statistics (from left to right): Study design: F(1,55) = 0.18, P = 0.669; F(1,61) = 0.33, P = 0.569; F(1,40) = 2.56, P = 0.117; Year: F(1,39) = 5.35, P = 0.026; F(1,39) = 4.17, P = 0.048; F(1,33) = 1.72, P = 0.199; Response: F(1,39) = 14.86, P < 0.001; F(1,47) = 0.29, P = 0.594; F(1,24) = 21.87, P < 0.001; Region: F(2,37) = 16.53, P < 0.001; F(2,37) = 8.62, P = 0.001; F(2,26) = 19.61, P < 0.001.
Extended Data Fig. 4
Extended Data Fig. 4. Mean difference or mean change effect sizes (±95% CI) calculated after outliers were removed.
See previous figures for details. Panels match: top left; Fig. 3, top right; Fig. 4; bottom left; Fig. 5, bottom right Extended Data Fig. 2. P values are for the plotted result and are the omnibus two-tailed test based on an F distribution. Top left panel test statistics (from left to right): Fire severity: F(1,38) = 6.16, P = 0.018; F(1,38) = 1.8, P = 0.188; F(1,28) = 17.69, P < 0.001; Fire frequency: F(3,36) = 9.83, P < 0.001; F(3,37) = 2.58, P = 0.068; F(3,29) = 30.56, P < 0.001; Inter-fire interval: F(2,38) = 31.14, P < 0.001; F(2,34) = 11.31, P < 0.001; F(2,26) = 4.53, P = 0.021; Unburnt area: F(2,19) = 7.32, P = 0.004; F(2,26) = 54.6, P < 0.001; F(2,21) = 2.57, P = 0.101. Top right panel test statistics (from left to right): Pre-fire drought: F(2,34) = 2.77, P = 0.077; F(2,44) = 17.99, P < 0.001; F(2,27) = 5.05, P = 0.014; P.A. or Not: F(1,42) = 1.37, P = 0.248; F(1,43) = 2.2, P = 0.145; F(1,31) = 13.3, P = 0.001; P.A. area: F(2,31) = 12.15, P < 0.001; F(2,40) = 1.25, P = 0.299; F(2,27) = 5.44, P = 0.01. Bottom left panel test statistics (from left to right): Taxon: F(5,27) = 131.46, P < 0.001; F(5,27) = 19.34, P < 0.001; F(5,17) = 17.82, P < 0.001; Ecosystem: F(3,29) = 6.41, P = 0.002; F(3,30) = 9.74, P < 0.001; F(3,24) = 3.99, P = 0.019. Bottom right panel test statistics (from left to right): Study design: F(1,44) = 3.37, P = 0.073; F(1,56) = 0.51, P = 0.478; F(1,38) = 0.76, P = 0.389; Year: F(1,36) = 12.88, P = 0.001; F(1,36) = 9.9, P = 0.003; F(1,33) = 0.07, P = 0.796; Response: F(1,36) = 4.97, P = 0.032; F(1,45) = 0.25, P = 0.619; F(1,26) = 28.11, P < 0.001; Region: F(2,34) = 20.51, P < 0.001; F(2,34) = 5.26, P = 0.01; F(2,27) = 4.42, P = 0.022.
Extended Data Fig. 5
Extended Data Fig. 5. Standardised effect sizes (±95% CI), with before-after designs retained in all analyses.
See previous figures for details. Panels match: top left; Fig. 3, top right; Fig. 4; bottom left; Fig. 5, bottom right Extended Data Fig. 2. P values are for the plotted result and are the omnibus two-tailed test based on an F distribution. Top left panel test statistics (from left to right): Fire severity: F(1,50) = 8.49, P = 0.005; F(1,54) = 0.39, P = 0.533; F(1,35) = 11.54, P = 0.002; Fire frequency: F(3,49) = 12.21, P < 0.001; F(3,46) = 4.49, P = 0.008; F(3,39) = 8.58, P < 0.001; Inter-fire interval: F(2,53) = 9.36, P < 0.001; F(2,59) = 14.16, P < 0.001; F(2,40) = 13.97, P < 0.001; Unburnt area: F(2,31) = 18.01, P < 0.001; F(2,43) = 1.06, P = 0.356; F(2,30) = 5.98, P = 0.007. Top right panel test statistics (from left to right): Pre-fire drought: F(2,46) = 2.96, P = 0.062; F(2,60) = 4.07, P = 0.022; F(2,37) = 3.92, P = 0.029; P.A. or Not: F(1,55) = 2.02, P = 0.161; F(1,60) = 0.95, P = 0.334; F(1,40) = 3.82, P = 0.058; P.A. area: F(2,54) = 0.62, P = 0.54; F(2,59) = 18.08, P < 0.001; F(2,40) = 2.19, P = 0.126. Bottom left panel test statistics (from left to right): Taxon: F(5,38) = 6.85, P < 0.001; F(5,42) = 23.4, P < 0.001; F(5,24) = 10.32, P < 0.001; Ecosystem: F(3,39) = 7.89, P < 0.001; F(3,42) = 2.98, P = 0.042; F(4,37) = 44.21, P < 0.001. Bottom right panel test statistics (from left to right): Study design: F(1,55) = 1.09, P = 0.302; F(1,61) = 1.26, P = 0.266; F(1,40) = 0.01, P = 0.917; Year: F(1,55) = 5.82, P = 0.019; F(1,61) = 15.46, P < 0.001; F(1,42) = 0.17, P = 0.682; Response: F(1,55) = 0.32, P = 0.576; F(1,61) = 2.09, P = 0.154; F(1,33) = 5.98, P = 0.02; Region: F(2,54) = 28.4, P < 0.001; F(2,60) = 27.24, P < 0.001; F(2,35) = 5.26, P = 0.01.
Extended Data Fig. 6
Extended Data Fig. 6. Distribution of covariate data.
Blue vertical lines indicate cut points for categories.

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MeSH terms