Southeastern Australian Forests Research Articles

Tree Mortality and Carbon Emission as a Function of Wildfire Severity in South-Eastern Australian Temperate Forests

Tree Mortality and Carbon Emission as a Function of Wildfire Severity in South-Eastern Australian Temperate Forests

Mapping prescribed fire severity in south-east Australian eucalypt forests using modelling and satellite imagery: a case study

Accurate fire severity maps are fundamental to the management of flammable landscapes. Severity mapping methods have been developed and tested for wildfire, but need further refinement for prescribed fire. We evaluated the accuracy of two severity mapping methods for a low-intensity, patchy prescribed fire in a south-eastern Australian eucalypt forest: (1) the Normalised Difference Vegetation Index (NDVI) derived from RapidEye satellite imagery, and (2) PHOENIX RapidFire, a fire-spread simulation model. We used each method to generate a fire severity map (four-category: unburnt, low, moderate and severe), and then validated the maps against field-based data. We used error matrices and the Kappa statistic to assess mapping accuracy. Overall, the satellite-based map was more accurate (75%; Kappa±95% confidence interval 0.54±0.06) than the modelled map (67%; Kappa 0.40±0.06). Both methods overestimated the area of unburnt forest; however, the satellite-based map better represented moderately burnt areas. Satellite- and model-based methods both provide viable approaches for mapping prescribed fire severity, but refinements could further improve map accuracy. Appropriate severity mapping methods are essential given the increasing use of prescribed fire as a forest management tool.

The drivers of wildfire enlargement do not exhibit scale thresholds in southeastern Australian forests

Wildfires are complex adaptive systems, and have been hypothesized to exhibit scale-dependent transitions in the drivers of fire spread. Among other things, this makes the prediction of final fire size from conditions at the ignition difficult. We test this hypothesis by conducting a multi-scale statistical modelling of the factors determining whether fires reached 10 ha, then 100 ha then 1000 ha and the final size of fires >1000 ha. At each stage, the predictors were measures of weather, fuels, topography and fire suppression. The objectives were to identify differences among the models indicative of scale transitions, assess the accuracy of the multi-step method for predicting fire size (compared to predicting final size from initial conditions) and to quantify the importance of the predictors. The data were 1116 fires that occurred in the eucalypt forests of New South Wales between 1985 and 2010.The models were similar at the different scales, though there were subtle differences. For example, the presence of roads affected whether fires reached 10 ha but not larger scales. Weather was the most important predictor overall, though fuel load, topography and ease of suppression all showed effects. Overall, there was no evidence that fires have scale-dependent transitions in behaviour. The models had a predictive accuracy of 73%, 66%, 72% and 53% accuracy at 10 ha, 100 ha, 1000 ha and final size scales. When these steps were combined, the overall accuracy for predicting the size of fires was 62%, while the accuracy of the one step model was only 20%. Thus, the multi-scale approach was an improvement on the single scale approach, even though the predictive accuracy was probably insufficient for use as an operational tool. The analysis has also provided further evidence of the important role of weather, compared to fuel, suppression and topography in driving fire behaviour.

Estimating tree and stand sapwood area in spatially heterogeneous southeastern Australian forests

Aims: Natural and anthropogenic changes in forests can have important influences on transpiration and water production. Understanding the effects of increasing disturbances, due for example to climate change and forest harvesting, requires detailed information on how forest density and structural attributes relate to transpiration. Mean annual transpiration of eucalypt forest communities is often strongly correlated with total cross-sectional sapwood area. Our aim was to test an efficient method for estimating sapwood area at 1.3 m height (SA 1.3 ) in a large number of trees to understand the spatial heterogeneity of tree and stand sapwood area within and between forest communities, and develop allometric relationships that predict SA1.3 with forest inventory data. We also apply tree competition models to determine the degree to which the relationship between SA 1.3 and tree basal area at 1.3 m height (BA 1.3 ) is influenced by competition. Methods: We visited 25 recently harvested southeastern Australian forest sites consisting of 1379 trees and 5 Eucalyptus species to evaluate a new efficient data collection method for estimating SA 1.3 with tree taper and stump dimensions data using mixed effects models. The locations of 784 stumps within one 5-ha site were accurately mapped using an unmanned aerial vehicle (UAV), and four distance-dependent tree competition models were applied across the site to explain within-stand variation in the ratio of SA 1.3 to BA 1.3 . Data from 24 additional sites, consisting of ten 15 m radial plots per site, were used to analyse within-site variation in R Ha (the ratio of stand sapwood area SA Ha to stand basal area BA Ha ). The radial plots were merged within each site to evaluate between-site variations in R Ha across the landscape. For predicting SA Ha with forest inventory data, we computed the relationship between SA Ha and a new index of total stem perimeter per hectare, defined as BA Ha N T , where N T is tree stocking density. Important Findings: Our 1379 measured stems represent the most comprehensive measure of sapwood area, surpassing the 757 measured stems in native eucalypt forests published in literature. The species-specific R Ha varied considerably across sites and therefore extrapolating SA Ha with spatially distributed BA Ha maps and a generalized R H a would introduce local uncertainty. We found that the species-specific stem perimeter index was more effective at capturing variability in SA Ha across the landscape using forest composition, structure and density data ( R 2 : 0.72-0.77). The strong correlation between tree SA 1.3 and BA 1.3 improved slightly using tree competition models ( R 2 increased from 0.86 to 0.88). Relating SA Ha to routinely measured forest inventory attributes within permanent plots and Light Detection and Ranging (LiDAR) data may provide opportunities to map forest water use in time and space across large areas disturbed by wildfire and logging.

Emissions from prescribed fires in temperate forest in south-east Australia: implications for carbon accounting

Abstract. We estimated emissions of carbon, as equivalent CO2 (CO2e), from planned fires in four sites in a south-eastern Australian forest. Emission estimates were calculated using measurements of fuel load and carbon content of different fuel types, before and after burning, and determination of fuel-specific emission factors. Median estimates of emissions for the four sites ranged from 20 to 139 Mg CO2e ha−1. Variability in estimates was a consequence of different burning efficiencies of each fuel type from the four sites. Higher emissions resulted from more fine fuel (twigs, decomposing matter, near-surface live and leaf litter) or coarse woody debris (CWD; > 25 mm diameter) being consumed. In order to assess the effect of declining information quantity and the inclusion of coarse woody debris when estimating emissions, Monte Carlo simulations were used to create seven scenarios where input parameters values were replaced by probability density functions. Calculation methods were (1) all measured data were constrained between measured maximum and minimum values for each variable; (2) as in (1) except the proportion of carbon within a fuel type was constrained between 0 and 1; (3) as in (2) but losses of mass caused by fire were replaced with burning efficiency factors constrained between 0 and 1; and (4) emissions were calculated using default values in the Australian National Greenhouse Accounts (NGA), National Inventory Report 2011, as appropriate for our sites. Effects of including CWD in calculations were assessed for calculation Method 1, 2 and 3 but not for Method 4 as the NGA does not consider this fuel type. Simulations demonstrate that the probability of estimating true median emissions declines strongly as the amount of information available declines. Including CWD in scenarios increased uncertainty in calculations because CWD is the most variable contributor to fuel load. Inclusion of CWD in scenarios generally increased the amount of carbon lost. We discuss implications of these simulations and how emissions from prescribed burns in temperate Australian forests could be improved.

Poor historical data drive conservation complacency: The case of mammal decline in south-eastern Australian forests

Forested ecosystems of south-eastern Australia now differ physically, compositionally and functionally from their condition prior to European settlement. Understanding these changes, and how native species and entire ecosystems have responded, is crucial for biodiversity conservation and ecosystem management. Here I argue that a combination of limited historical information and a knowledge base biased towards modern ecological studies has resulted in a distorted perception of ecosystem condition, hindering the instigation of effective biodiversity conservation measures. This argument is based on recently obtained information about changes to the non-volant mammal community, which reveals relatively recent but underreported ecological changes, including major declines in species distribution and abundance, shifts in niche utilization and associated disruption of ecosystem functions. Ultimately, many mammal species are being denied the capacity to function to the extent they did historically. Following this re-assessment, it is evident that current forest management does not adequately address contemporary conservation dilemmas posed by detrimental ecosystem changes. This is especially salient when most of the factors responsible for causing changes to the mammal community are still active and include forest management and utilization activities. Therefore, additional conservation measures are essential to meet forest stewardship and biodiversity conservation obligations. For the health, functionality and sustainability of forested ecosystems, native mammal species must be capable of functioning to their ecological potential and occupy their original niche. This will be facilitated by the suppression of threatening processes (primarily exotic species), ensuring ecologically sensitive fire regimes and the reintroduction/translocation of missing species. The recovery or restoration of forest functionality based on mammal conservation should have wide-scale benefits for biodiversity conservation.

Groundwater Constraints on Simulated Transpiration Variability over Southeastern Australian Forests

AbstractA land surface scheme with and without groundwater–vegetation interactions is used to explore the impact of rainfall variability on transpiration over drought-vulnerable regions of southeastern Australia. The authors demonstrate that if groundwater is included in the simulations, there is a low correlation between rainfall variability and the response of transpiration to this variability over forested regions. Groundwater reduces near-surface water variability, enabling forests to maintain transpiration through several years of low rainfall, in agreement with independent observations of vegetation greenness. If groundwater is not included, the transpiration variability matches the rainfall variability independent of land cover type. The authors’ results suggest that omitting groundwater in regions where groundwater sustains forests will 1) probably overestimate the likelihood of forest dieback during drought, 2) overestimate a positive feedback linked with declining transpiration and a drying boundary layer, and 3) underestimate the impact of land cover change due to inadequately simulating the different responses to drought for different land cover types.

Effective detection methods for medium-sized ground-dwelling mammals: a comparison between infrared digital cameras and hair tunnels

Context Conservation planning for threatened species depends on improved knowledge of the whereabouts of critical populations and thus the development of optimal detection methods. Aims To compare the effectiveness of infrared cameras and hair tunnels for detecting small to medium-sized ground-dwelling mammals in south-eastern Australian forests. Methods Reconyx PC90 cameras were paired with Handiglaze hair tunnels at 110 stations in south-eastern New South Wales. All devices were baited using rolled oats, peanut butter and pistachio essence and left in situ for a minimum duration of 30 days. Camera detection data were analysed for the first 15 and 30 days, whereas hair-tunnel detection data were analysed for the entire duration of deployment. Linear mixed models with site as a random effect and device as a fixed effect were developed for mammal species richness. Linear mixed logistic regression models for binary data were developed for detection probabilities of five taxa of interest, namely, Isoodon, Perameles, Potorous, Trichosurus and Wallabia. Key results Hair tunnels detected eight mammal species, whereas cameras detected 18 species. Modelled detection rates using cameras were 3.16 ± 0.21 species per site after 15 days and 4.24 ± 0.23 species per site after 30 days, whereas hair tunnels detected 0.34 ± 0.21 species over the entire deployment. Cameras were therefore approximately 9–12 times better at measuring mammal richness than were hair tunnels, depending on survey duration. In all calculations, the probability of detecting the five taxa of interest was significantly greater using cameras than using hair tunnels. Conclusions Infrared cameras and hair tunnels offer ethical advantages over direct detection methods such as cage trapping for small to medium-sized ground-dwelling mammals. Cameras also offer practical benefits because they work for protracted periods, without frequent checking by field researchers. Cameras are more effective at detecting a wide range of species than are hair tunnels and are significantly better for detecting the taxa we examined. Unlike hair tunnels, cameras sometimes allow for the identification of individual animals, and provide information about frequency of habitat use, reproductive status and aspects of behaviour. Implications On a unit by unit basis, infrared cameras are a far more efficient way to census a broad spectrum of ground-dwelling mammals than are hair tunnels.

BVOC emissions from mechanical wounding of leaves and branches of Eucalyptus sideroxylon (red ironbark)

Emissions of biogenic volatile organic compounds (BVOCs) from mechanical wounding of leaves and branches of plants can contribute to the atmospheric burden of volatile organic compounds (VOCs) in both (a) urban airsheds (from urban garden maintenance) and (b) the global atmosphere (from large scale forest harvesting). These emissions of BVOCs are poorly understood and quantified, and their role in urban and global emissions inventories neglected. This paper presents measurements of the magnitude, duration and composition of emissions of BVOCs, carbon dioxide (CO2) and methane (CH4) from freshly cut leaf mulch and wood chips derived from a common eucalypt tree, Eucalyptus sideroxylon (red ironbark), found in southeastern Australian forests and gardens. The emissions of BVOCs from freshly cut and shredded leaves and wood of E. sideroxylon were found to be 2.3 ± 0.6 and 0.05 ± 0.04 mg g-1 DM (Dry Mass) from leaf mulch and wood chips respectively and to last typically for 1 day following cutting. Three sampling techniques were used for VOC speciation and the 12 most abundant BVOCs released from the mulch materials were identified. The specific BVOCs emitted in order of decreasing abundance from leaf mulch are: (a) stored plant oils, 1,8-cineole, α–pinene and o-cymene which make up the major part of the emissions, (b) a minor contribution from chemicals associated with environmental stress and wound defence, (Z)–3–hexenyl acetate, (E)-2-hexenal and (Z)-3-hexen-1-ol, and (c) a second minor contribution from metabolic products, acetaldehyde and acetone. The observed integrated emissions of BVOCs from leaves following mulching are equivalent to more than half and perhaps all of the likely stored plant oils in the leaves. For the two comparable studies available, one of a plant with stored oils (this study) and one of a plant without stored plant oils, the emissions of leaf wound defence BVOCs are in the same range for both plants. In the plant with stored plant oils, the plant oil emissions are about a factor of 11 larger in emission rate than the plant wound defence BVOCs. A compilation of available leaf wounding BVOC emission studies indicates that for plants with stored plant oils, plant oil emissions dominate, whereas with other plants, leaf wound defence BVOCs dominate the emissions.

Spatial ecology of Sooty Owls in south-eastern Australian coastal forests: implications for forest management and reserve design

We investigated the home-range size and habitat use of eight Sooty Owls (Tyto tenebricosa tenebricosa) in coastal forests in East Gippsland, Victoria, Australia, between November 2006 and January 2008. The size of home-ranges varied widely; based on 95% adaptive kernel estimates, the average size of home-ranges of males was 3025 ha (±1194 s.d., n = 3), whereas that of females was 994 ha (±654 s.d., n = 5). Sooty Owls utilised a broad range of ecological vegetation classes and topographical features for roosting and foraging at a greater scale than previously assumed. There was minimal selection for habitat types based on floristic composition, primarily only avoiding heathlands (for foraging and roosting) and selecting particular dense foliage (rainforest and riparian scrub) for foliage roosting. Two Owls maintained home-ranges close to logged areas, with logging regrowth (<45 years old) being strongly avoided by both individuals. We recommend that the size of individual reserves for Sooty Owls in commercial forests should be increased to more closely resemble the core spatial resource requirements needed by a pair. Reserves should be largest where they feed predominantly on hollow-dependent prey. Most importantly, rather than conservation measures just focussing on the spatial requirements of Sooty Owls, efforts should be directed towards retaining high densities of crucial resources, such as hollow-bearing trees and mammalian prey species throughout the landscape.

Effects of weather, fuel and terrain on fire severity in topographically diverse landscapes of south-eastern Australia

The effects of weather, terrain, fuels on fire severity were compared using remote sensing of the severity of two large fires in south-eastern Australian forests. The probability of contrasting levels of fire severity (fire confined to the understorey vs. tree canopies consumed) was analysed using logistic regression. These severities equate to extremes of fire intensity ( 10,000 kW m−1), consequent suppression potential (high vs. nil) and potential adverse ecological impacts on vertebrate fauna and soils (low vs. high). Weather was the major influence on fire severity. Crown fire was absent under non-extreme weather and but more likely under extreme weather, particularly on ridges in vegetation unburnt for >10 years. Crown fire probability was very low in recently burnt vegetation (1–5 years) and increased at higher fuel ages. In all cases, fire severity was lower in valleys, probably due to effects of wind protection and higher fuel moisture in moderating fire behaviour. Under non-extreme weather, fires are likely to be suppressible and burn heterogeneously, due to the influence of topographic position, slope and fuel load. Under extreme weather, fires are influenced only by fuel and topographic position, and probability of suppression on accessible ridges will be low except in recently burnt (i.e. 1–5 year old) fuels. Topographically imposed variation may mitigate adverse ecological effects on arboreal fauna and soil erosion potential.

Comment — Economics of a nest-box program for the conservation of an endangered species: a re-appraisal

Spring et al. (D.A. Spring, M. Bevers, J.O.S. Kennedy, and D. Harley. 2001. Can. J. For. Res. 31: 1992–2003) recently published a paper on the economics of a nest-box program for the endangered arboreal marsupial, Leadbeater's possum (Gymnobelideus leadbeateri) in southeastern Australian forests. While their paper is a useful one, there are some important limitations of nest-box programs that need to be highlighted. In the case of Leadbeater's possum, we have undertaken extensive nest-box studies in Victoria mountain ash (Eucalyptus regnans F. Muell.) forests, where the vast majority of populations of the species now occur. Although large numbers of nest boxes have been deployed, very few have actually been occupied, which is a major problem since the effectiveness of any nest-box program will depend on patterns of use by the target species. Given very low levels of nest-box occupancy, harvesting regimes such as those that lead to on-site tree retention are needed to better conserve hollow-dependent species like Leadbeater's possum. Moreover, the need for nest boxes in the first place indicates that logging practices are presently not ecologically sustainable, and modified forestry practices need to be adopted.

A simple landscape‐scale test of a spatially explicit population model: patch occupancy in fragmented south‐eastern Australian forests

The results of a landscape‐scale test of ALEX, a widely used metapopulation model for Population Viability Analysis (PVA), are described. ALEX was used to predict patch occupancy by the laughing kookkaburra and the sacred kingfisher in patches of eucalypt forest in south‐eastern Australia. These predictions were compared to field surveys to determine the accuracy of the model. Predictions also were compared to a “naïve” null model assuming no fragmentation effects. The naïve null model significantly over‐predicted the number of eucalypt patches occupied by the sacred kingfisher, but the observed patch occupancy was not significantly different from that predicted using ALEX. ALEX produced a better fit to the field data than the naïve null model for the number of patches occupied by the laughing kookaburra. Nevertheless, ALEX still significantly over‐predicted the number of occupied patches, particularly remnants dominated by certain forest types – ribbon gum and narrow‐leaved peppermint. The predictions remained significantly different from observations, even when the habitat quality of these patches was reduced to zero. Changing the rate of dispersal improved overall predicted patch occupancy, but occupancy rates for the different forest types remained significantly different from the field observations. The lack of congruence between field data and model predictions could have arisen because the laughing kookaburra may move between an array of patches to access spatially separated food and nesting resources in response to fragmentation. Alternatively, inter‐specific competition may be heightened in a fragmented habitat. These types of responses to fragmentation are not incorporated as part of traditionally applied metapopulation models. Assessments of predictions from PVA models are rare but important because they can reveal the types of species for which forecasts are accurate and those for which they are not. This can assist the collection of additional empirical data to identify important factors affecting population dynamics.

Coexistence of a locally undifferentiated foraging guild: avian snatchers in a southeastern Australian forest

AbstractThree species of sexually dichromatic, insectivorous birds (Golden Whistler,Pachycephala pectoralis;Rufous Whistler,Pa. rufiventris;Rose Robin,Petroica rosea) employ a characteristic foraging manoeuvre (snatching or sally‐striking) disproportionately often, leading several studies to group them together in one foraging guild. The three species synchronously co‐occupy an extensive eucalypt forest east of Melbourne, Australia (Olinda State Forest). All assemble in relatively high densities in late winter and through spring and early summer to breed. Log‐linear modelling of use of foraging techniques, substrate, plant species and heights within the forest indicate that all six species–gender groups virtually do not differ from one another: a situation in which very similar species coexist at high densities. The results are considered in the context of interspecific competition among ecologically similar species and it is suggested how such a situation might arise and be sustained. The absence of gender‐specific differentiation within species is also addressed.

Coexistence of a locally undifferentiated foraging guild: avian snatchers in a southeastern Australian forest

Coexistence of a locally undifferentiated foraging guild: avian snatchers in a southeastern Australian forest

Molecular identification of co-occurring Cortinarius and Dermocybe species from southeastern Australian sclerophyll forests

Molecular identification of co-occurring Cortinarius and Dermocybe species from southeastern Australian sclerophyll forests

Molecular identification of co-occurring Cortinarius and Dermocybe species from southeastern Australian sclerophyll forests

The ability of restriction fragment length polymorphism (RFLP) analysis of the rDNA internal transcribed spacer (ITS) region to discriminate 10 co-occurring Cortinarius and Dermocybe species at a southeastern Australian sclerophyll forest site was assessed. Using the basidiomycete-specific primers ITS1F and ITS4B, some taxa were separated on the basis of individual RFLP patterns derived using the restriction endonucleases Hae III or Hinf I. Combined data from both endonucleases were, however, required to separate all taxa [Dermocybe austro-veneta Clel. (Moser & Horak), C. rotundisporus Clel. & Cheel, C. archeri Berk., C. sinapicolor Clel., C. violaceus (L.: Fr.) S.F.Gray, C. radicatus Clel. and four morphologically-distinct, but unidentified Cortinarius spp.]. ITS sequence comparisons confirmed that D. austro-veneta belongs in Dermocybe, that C. rotundisporus is correctly placed in subgenus Phlegmacium, and suggest that Australian C. violaceus collections are not conspecific with northern hemisphere C. violaceus.

Effectiveness of pitfall/drift-fence systems for sampling small ground-dwelling lizards and frogs in southeastern Australian forests

The effectiveness of various pitfall trap designs and pitfall/drift fence systems for sampling small ground-dwelling lizards and frogs in the forests of southeastern Australia was examined. Pitfall/drift fence systems employing long drift fences were more effective than short or no-fence systems in terms of the number of individuals and species caught, but were time consuming and caused considerable habitat disturbance. Various pitfall trap designs were compared. Generally, simple open-necked and funnel traps were more effective than traps with shelter and shelter/drift arm traps. It is suggested that in forested habitats, groups of individual open necked pitfall traps or short-fence systems may be just as effective and no more costly in installation time than systems employing long drift fences and more complex bap types.

A winter's tale: Among‐year variation in bird community structure in a southeastern Australian forest

Abstract The bird community structure of an undisturbed forest (Olinda State Forest) east of Melbourne, Victoria, varied greatly among the winters of 1993, 1994 and 1995. Increases in the total density of all diurnally active species were as much as 66% between winters [381 versus 633 birds per 50 ha (the density unit used throughout)]. Community structure differed significantly among all three winters, although 1993 and 1994 differed most (1995 was intermediate). One of the striking features was the heterogeneity in patterns among species, families and foraging guilds over the three winters: some taxa (guilds) showed significantly higher densities in the middle year (1993 &lt; 1994 &gt; 1995), others increased monotonically (1993 &lt; 1994 &lt; 1995), while others increased from 1993 to 1994 and maintained those densities in 1995. The species showing significantly higher densities in 1994 were mostly nectarivorous, which seemed to accord with profuse and sustained flowering by Eucalyptus cypellocarpa in 1994 alone. The results are discussed in the context of non‐equilibrial community dynamics, large‐ versus small‐scale processes, and the implications of this magnitude of variation in unperturbed forests for environmental monitoring and impact assessments.

Modelling distributions of arboreal and ground-dwelling mammals in relation to climate, nutrients, plant chemical defences and vegetation structure in the eucalypt forests of southeastern Australia

Numerous studies over the past 15 years have investigated relationships between the distributions of arboreal and ground-dwelling mammals and environmental, structural and leaf compositional variables in the temperate Eucalyptus forests of southeastern and northeastern New South Wales, Australia. This paper draws together the general trends emerging from these studies and identifies some clear messages for the future modelling of regional biodiversity in these forests. The studies on arboreal mammals (all are marsupials in these forests) reviewed here generally fall into two broad categories: those that conclude that the nutrient status of forests is the prime determinant of habitat quality for arboreal marsupials and those that put equal or greater emphasis on variables related to structural characteristics of forests. Recent studies suggest a hierarchical model that is consistent with both of these emphases. They postulate that a proportion of temperature eucalypt forests, regardless of their climatic or structural characteristics, cannot support permanent populations of arboreal marsupials, especially leaf-eating species, due to low food quality and/or high phytochemical toxicity. Above a postulated nutritional or phytotoxicological ‘threshold’, food quality is adequate and other variables, including climatic and structural ones, apparently interact to determine habitat quality. Hence, differences in the extent to which different studies sample regional environmental variability, the range of nutrient status and forest structure, are likely to greatly affect which variables appear most significant in models of habitat requirements. Structural characteristics (measured as habitat complexity) of the forest have emerged as explanatory variables for the ground-living mammals also. Variables such as nutrients, lithology, terrain and climate exhibit a different trend to that seen for arboreal marsupials. Relative abundance of small ground-dwelling mammals is negatively correlated with site nutrient status as indicated by nutrient concentrations in tree foliage. Small mammals are present at all measured nutrient levels, but their abundance falls substantially as habitat complexity decreases. The influence of nutrients is masked in habitats of high complexity, there being no relationship with nutrient status. Many ground-living mammals occur across the gradients of lithology, terrain and climate, although there is wide variation in relative abundance for some species. The importance of structural variables for explaining distributions of both arboreal and ground-living fauna in eucalypt forests indicates that adequate modelling of habitat requirements for these fauna can only be achieved if surveys obtain adequate data on forest structure to encompass gradients in seral stage and disturbance history. The present-day mammalian fauna of the southeastern Australian forests has been influenced strongly by the effects of urbanisation, clearing for farming, forestry activities and fire on forest structural complexity and nutrient dynamics as well as by predation by introduced camivores. While modelling with respect to broadly defined climatic and terrain variables might be useful for broad-scale spatial prediction of faunal distributions, such models are unlikely to provide descriptions of habitat requirements or predictions of impacts of forest management at a scale necessary for sustainable management of faunal biodiversity.