The contest for the tall forests of south-western Australia and the discourses of advocates

Wardell‐Johnson, Grant; Wardell‐Johnson, Angela; Schultz, Beth; Dortch, Joe; Robinson, Todd; Collard, Len; Calver, Michael C.

doi:10.1071/pc18058

Cited by 8 publications

(12 citation statements)

References 75 publications

(102 reference statements)

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“…These three species experience mixed‐severity fire as well: regenerating prolifically after high‐severity fire (Harvey et al., 1980; Lara et al., 1999; Person & Hallin, 1942), and surviving repeated low‐intensity fires, such as those frequent fires lit by Native Americans (Swetnam, 1993; Orville, 2008; Veblen et al., 1999). Likewise, although E. regnans forests are promoted as exemplars of infrequent, stand‐replacing fires, there is an evidence that infrequent low‐severity fires, possibly set by Indigenous Australians, may have maintained grassy understories in some of these forests prior to European invasion (Ashton, 1958, 1981), though aboriginal management of TWEF was likely much less intensive than that of drier forests (Wardell‐Johnson et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

Bioclimatic drivers of fire severity across the Australian geographical range of giant Eucalyptus forests

et al. 2021

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1. The relationships between productivity, fire frequency and fire severity shape the distribution of plant communities globally. Dry forests are expected to burn frequently and wet forests to burn infrequently. However, the effect of productivity on intensity and severity of wildfire is less consistent and poorly understood.One productive ecosystem where this is especially true is the Australian tall wet Eucalyptus-dominated forest (TWEF), which spans wet areas across the continent.This study aims to characterise how climate shapes the likelihood of low-and high-severity wildfire across Australian TWEF.2. We performed a continental-scale analysis of fuels in 48 permanent plots in earlymature stage TWEF across four climate regions in Australia. We estimated fuel loads and measured understorey microclimate. We then obtained historical fireweather observations from nearby meteorological stations and used fuel moisture and fire behaviour equations to predict the historical frequency with which TWEF could burn and what fire severities were expected. We investigated how this varies across the different TWEF climate regions. Lastly, we validated our approach by remeasuring eight plots that burned unexpectedly post-measurement.3. We found that surface fuels in cooler, moister regions were available to burn 1-16 days per year historically, with only low-severity, surface fire possible most of these days: high-severity fire was only possible under rare, extreme fire-weather conditions. However, in warmer, drier regions, fuels were available to burn 23-35 days annually, and high-severity fire was more likely than low-severity fire.Validation showed that we slightly overestimated flame heights, inflating highseverity risk estimates. If we used elevated fuel loads to predict flame heights, however, high-severity fire was more likely than low-severity fire everywhere.Lastly, the likelihood of high-severity fire increased with increasing temperature and worsening fire weather. Synthesis.Fire activity in early-mature TWEF is limited by climatic constraints on fire weather and availability to burn, with high-severity fire more likely in warmer, drier regions than in cooler, wetter ones. This indicates a particularly worrisome vulnerability to climate change, given TWEF's diminished ability to recover from disturbance in a warmer world. The occurrence of both low-and high-severity fire means the fire regimes of TWEF are best described as mixed severity.

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Section: Discussionmentioning

confidence: 99%

Bioclimatic drivers of fire severity across the Australian geographical range of giant Eucalyptus forests

et al. 2021

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“…Old growth forests and woodlands have a wide range of key ecological and ecosystem service values (Scotts 1991;Wardell-Johnson et al 2018). We sought to quantify temporal changes in the spatial extent of old growth forest and woodland in different EVCs in Victoria.…”

Section: Discussionmentioning

confidence: 99%

“…The high conservation and ecosystem service values of intact forests, including those dominated by old growth stands have long been recognised in many parts of the world (Franklin et al 1981;Scotts 1991;Bart and Forsman 1992;Spies and Franklin 1996;Van Pelt 2008;Gibson et al 2011;Watson et al 2018). This includes in Australia (Woodgate et al 1994(Woodgate et al , 1996Burgman 1996;Lindenmayer et al 2000;Wardell-Johnson et al 2018; Office of the Conservation Regulator 2019), where a range of studies have shown that, for example: (1) old growth stands are where fire severity is lowest relative to forests of younger age (Taylor et al 2014;Winoto-Lewin et al 2020);…”

Section: Introductionmentioning

confidence: 99%

Extensive recent wildfires demand more stringent protection of critical old growth forest

Lindenmayer

Taylor

2020

Pac. Conserv. Biol.

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Old growth forests have many key values, but temporal changes across their spatial extent are poorly understood. This includes large parts of Australia and is a major knowledge gap given the extent of human and natural disturbances in the Australian forest estate over past decades. We integrated spatial data on the timing and extent of fire and logging across mapped forest and woodland cover in different Ecological Vegetation Class (EVC) groups to quantify disturbance of the old growth forest and woodland estate in Victoria since 1995, including after the 2019–20 wildfires. We found ~77% of old growth forest and woodlands have been disturbed by fire and logging over the past 25 years. Disturbance was particularly marked in some EVCs, such as the Wet and Damp Forest and the Subalpine Woodlands. In contrast, relatively little of the Modelled Old Growth Forest and Woodland has been disturbed between 1995 and 2020 in other EVCs such as in Plains Woodlands and Heathy Woodlands. Wildfire was the primary driver of disturbance in Modelled Old Growth Forest and Woodland. We argue that a range of strategies is critical to increase protection of undisturbed old growth forest. These include re-assessing disturbance data layers to ensure that areas of old growth that have been burned at low severity are protected, and reducing the size of old growth patches to be conserved. There is also a need to increase levels of protection of young forests to enable them to grow through to an old growth state.

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“…Old growth characteristics also vary with site features such as moisture and nutrient availability: higher productivity sites generally support forests with bigger trees, more dead wood, increased heterogeneity, and higher biodiversity (Spetich et al, 1999;Chase, 2010;Hämäläinen et al, 2018). These forests often include large old trees that form keystone ecological structures which are at risk globally (Lindenmayer et al, 2012(Lindenmayer et al, , 2014Lutz et al, 2012;Wardell-Johnson et al, 2018). Big-treed ecosystems have exceptionally high value as biodiversity hubs, carbon banks, and climate refugia (Holt and Hadfield, 2007;Ashcroft, 2010;Hauer et al, 2016).…”

Section: Big-treed Old Growthmentioning

confidence: 99%

Estimating the amount of British Columbia’s “big-treed” old growth: Navigating messy indicators

Price¹,

Daust²,

Daust³

et al. 2023

Front. For. Glob. Change

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British Columbia’s (BC) diverse forest ecosystems include highly productive old growth with global importance for carbon storage and biodiversity. Current estimates of the remaining amount of “big-treed” old growth vary 10-fold, creating uncertainty that challenges provincial attempts to shift management policy toward ecological integrity. This uncertainty arises from using different remotely sensed indicators and definitions of tree size. No ideal indicator exists. We attempt to improve clarity by evaluating the reliability of candidate indicators, calibrating selected indicators to improve consistency, and generating multiple estimates of the amount of big-treed old growth using calibrated indicators. To evaluate reliability, we compared inventory estimates of tree size and site productivity with measured tree size in 1,945 ground plots. To assess the amount of big-treed old growth, we determined an equivalent “big” size threshold for each indicator and calculated the area of old growth above the size threshold. Stand volume, tree density, basal area, and diameter estimates performed poorly; we selected tree height and two measures of site productivity for further analysis. Estimated tree height best indicated the current old growth size, followed by inventory-based site index and finally ecosystem-based site index. The calibrated indicators agreed that very little remaining old growth supports large trees (1.5–3.3% for the biggest trees; 6–13% including medium-sized trees that represent the largest growing trees in lower productivity interior ecosystems). Tree height cannot be used to compare the remaining area of big-treed old growth to the area expected naturally, an important input for ecological risk assessment and conservation planning because height data are lost from the inventory after harvest. The two calibrated site productivity indicators agreed that the amount remaining is less than 30% of the expected historical amount, posing a high risk to biodiversity and resilience. We recommend using estimated height to identify the biggest remaining old-growth stands for regional planning and calibrated inventory-based site index for risk assessment until a detailed ecosystem mapping has been verified to represent old-growth variability. To reduce uncertainty, we suggest that planning groups compare several indicators and analysis approaches, adjusted to ensure equivalence, and use precaution to avoid any unknowingly increasing risks.

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The contest for the tall forests of south-western Australia and the discourses of advocates

Cited by 8 publications

References 75 publications

Bioclimatic drivers of fire severity across the Australian geographical range of giant Eucalyptus forests

Bioclimatic drivers of fire severity across the Australian geographical range of giant Eucalyptus forests

Extensive recent wildfires demand more stringent protection of critical old growth forest

Estimating the amount of British Columbia’s “big-treed” old growth: Navigating messy indicators

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