Eucalypt Woodland Research Articles

Relationships among soil fertility, native plant diversity and exotic plant abundance inform restoration of forb‐rich eucalypt woodlands

AbstractAim Water and nutrient availability are major limits to productivity in semi‐arid ecosystems; hence, ecological restoration often focuses on conserving or concentrating soil resources. By contrast, nutrient enrichment can promote invasion by exotic annuals, leading to restoration approaches that target reduction of soil nutrients. We aimed to explore potential biodiversity trade‐offs between these approaches by investigating relationships among soil nutrients, exotic annuals and native plant diversity and composition. In particular, we investigated the hypothesis that native plant diversity in semi‐arid to temperate woodlands reflects the productivity–diversity hypothesis, leading to hump‐backed relationships with soil nutrients such that (1) native plant diversity declines with increasing nutrient enrichment and (2) native diversity is limited at the lowest levels of soil fertility.Location Fragmented, long‐ungrazed Eucalyptus loxophleba subsp. loxophleba (York gum)–Acacia acuminata (jam) woodlands in the wheatbelt of South‐Western Australia.Methods We conducted stratified surveys of floristic composition and topsoil nutrient concentrations in 112 woodland patches. We used generalized linear models, structural equation models and ordinations to characterize relationships among soil nutrients, rainfall, exotic annuals and patch‐scale (100 m2) native plant composition and diversity.Results Patch‐scale native plant diversity declined strongly with increasing exotic abundance. This was partly related to elevated soil nutrient concentrations, particularly total nitrogen and available phosphorus. By contrast, there was little evidence for positive correlations between soil nutrients and native diversity, even at very low soil nutrient concentrations.Main conclusions Minimizing weed invasions is crucial for maximizing native plant diversity in E. loxophleba woodlands and could include nutrient‐depleting treatments without substantially compromising the functional capacity of soils to maintain native plant richness and composition. More broadly we emphasize that understanding relationships among ecosystem productivity, plant diversity and exotic invasions in the context of associated theoretical frameworks is fundamental for informing ecological restoration.

Invictokoala monticola gen. et sp. nov. (Phascolarctidae, Marsupialia), a Pleistocene plesiomorphic koala holdover from Oligocene ancestors

Koalas (Phascolarctidae) are uncommon elements within the Australian fossil record. The earliest representatives are recorded from late Oligocene rainforest assemblages of central Australia. In contrast, the extant Koala Phascolarctos cinereus Blainville, 1816 (the only surviving member of a once diverse family) is found only in eastern Australian open woodlands. Extinction of koalas from rainforests was previously thought to have occurred after the middle Miocene. Recent systematic cave excavations at Mt. Etna, central eastern Queensland, Australia, have revealed several remarkable new middle Pleistocene vertebrate assemblages that are dominated by rainforest-adapted taxa. Within one of the deposits, we have identified a new, but archaic, genus and species of koala. Invictokoala monticola gen. et sp. nov. shares affinities with the most plesiomorphic member of the family, Madakoala Woodburne et al., 1987 (late Oligocene), but is distinguished by possessing higher-crowned upper molars, with a tricsupate (rather than linear) paraconule on M2 (autapomorphic condition within koalas), closely positioned stylar cusps, and better-developed posterior cingulae. Thus, not only does I. monticola represent a ‘holdover’ from an Oligocene ancestor, but the Madakoala–Invictokoala stem represents a ‘ghost’ lineage within the Phascolarctidae, with no representatives known between the late Oligocene and middle Pleistocene. Previously, it was thought that the post-middle Miocene loss of koalas from rainforests may have been a result of a co-evolved dependence of koalas to open eucalypt woodlands, and/or competitive exclusion with koala-like rainforest-adapted ringtail possums. However, the inferred diet of middle Pleistocene I. monticola (i.e. non-Eucalyptus) and coeval occurrence with numerous rainforest-adapted ringtail possums does not support that hypothesis. It appears more likely that koalas had always been closely associated with rainforests, at least until the late Quaternary extinction of I. monticola. Generally, the paucity of rainforest faunal assemblages, and specifically, records of fossil koalas through the late Cenozoic drastically limits our understanding of their evolution.

The influence of sampling strategies and spatial variation on the detected soil bacterial communities under three different land-use types

To determine the influence of pooling strategies on detected soil bacterial communities, we sampled 45 soil cores each from a eucalypt woodland, a sown pasture and a revegetated site in an Australian landscape. We assessed the spatial variation within each land-use plot, including the influence of sampling distance, soil chemical characteristics and, where appropriate, proximity to trees on the soil bacterial community, by generating terminal restriction fragment length polymorphism profiles of the bacterial 16S rRNA genes. The soil bacterial community under the revegetated site was more similar to the original woodland than the pasture, and this result was found regardless of the soil- or the DNA-pooling strategy used. Analyzing as few as eight cores per plot was sufficient to detect significant differences between the bacterial communities under the different plots to be distinguished. Soil pH was found to be most strongly associated with soil bacterial community composition within the plots and there was no association found with proximity to trees. This study has investigated sampling strategies for further research into the transitions of soil microbial communities with land-use change across broader temporal and spatial scales.

Double sampling to assess the accuracy of ground‐based surveys of tree hollows in eucalypt woodlands

AbstractGround‐based surveys of tree hollows often give poor estimates of hollow abundance in forests. Woodlands have shorter trees and a more open structure than forests, which may make hollows easier to detect. Therefore, one would expect ground‐based surveys of tree hollows to be more accurate in woodlands than in forests. We compared hollow counts from ground‐based and climbing surveys (double sampling) for four species of Eucalyptus trees in woodlands of central‐western New South Wales, Australia: E. camaldulensis Dehnh, E. melliodora A. Cunn. ex Schauer, E. microcarpa Maiden and E. populnea F. Muell. ssp. bimbil L.A.S. Johnson & K.D. Hill and E. melliodora A. Cunn. ex Schauer. Overall, 83% of hollow‐bearing trees and 93% of trees without hollows were correctly classified by ground‐based surveys. Mean difference in hollow counts of ground‐based surveys to climbed surveys was 1.7 hollows ± 0.2 SE (all species combined) with 91% of ground‐based hollow counts being within five of the actual number of hollows. The error in ground‐based counts of hollows in E. microcarpa was larger than for the other three species. Errors in all species resulted from both overestimation and underestimation of hollow abundance by ground‐based surveys. A larger error was associated with the detection of hollows located in branches compared with hollows located in the main trunk(s). Total number of hollows in the tree (based on climbing surveys), crown area or maximum trunk diameter were significant predictors of ground‐based survey accuracy. Overall, the accuracy associated with ground surveys was relatively high and generally error rates were lower than those published for forests.

Effects of exotic grass invasion on spatial heterogeneity in the ground-layer of grassy woodlands

We quantified the effects of exotic annual grass invasion on the ground-layer structure of grassy eucalypt woodlands, with the aim of determining if weed invasion decreased gap size and plant basal area leading to reduced spatial heterogeneity. We measured plant density, distance between plants and basal plant area in woodland sites which ranged from zero to 100% exotic plant cover in the ground-layer. The ground-layer in uninvaded woodlands was heterogeneous, with a large variation in basal plant area and distance between plants. Exotic annual grass density was positively correlated with total plant density, whereas native plant density was negatively correlated. Total plant basal area decreased as total plant density increased, with a lower total plant area in exotic dominated transects compared to native dominated. Variation in basal plant area decreased with increasing plant density. Exotic annual grasses were more closely spaced together (smaller gap size) and had a smaller basal area than the native grasses and rushes. There was also less variation in basal area and gap size with individual exotic annual grasses compared to the native grasses. Inter-plant distance was greater for both the native and exotic grasses when they had native grasses neighbouring them instead of exotic grasses. These findings show that woodlands invaded by exotic annual grasses have relatively less spatial heterogeneity in the ground-layer. These results have implications for other aspects of perennial grassy ecosystems invaded by annual grasses, including plant recruitment and restoration strategies.

How do slow-growing, fire-sensitive conifers survive in flammable eucalypt woodlands?

Question: To what extent do low flammability fuel traits enhance the survival and persistence of fire-sensitive (slowing-growing, non-serotinous, nonresprouting) dominant trees in highly flammable landscapes, under varying fire-weather conditions? Location: Mixed forests co-dominated by flammable Eucalyptus species and fire-sensitive Callitris glaucophylla in Pilliga State Forest, southeast Australia. Methods: The influence of vegetation composition (relative abundance of Callitris andflammable Eucalyptus) onfire intensity and survival of fire-sensitive Callitris was assessed across gradients of Callitris abundance in mixed Eucalyptus‐Callitris forests that burned under low-moderate and extreme fire-weather conditions. Results: In areas that burned under low-moderate fire-weather conditions, as Callitris abundance increased, fire intensity declined and Callitris survival increased (46%). By comparison, in extreme fire-weather conditions, lower fire intensity at higher levels of Callitris abundance, was not sufficient to increase Callitris survival (4%). Callitris survival was also positively related to trunk diameter. Ground fuel type, but not biomass, varied with vegetation composition. Conclusions: These results demonstrate that flammable feedbacks, mediated by low flammability fuel traits of dominant trees, can provide an important mechanism for enhancing the survival and persistence of slow-growing, nonserotinous, non-resprouting, fire-killed trees in highly flammable landscapes. By modifying vegetation and fuel structure, patches of fire-sensitive Callitris reduce fire intensity, and thereby reduce Callitris mortality, enhancing population persistence. However, this feedback loop is insufficient to ensure Callitris survival under extreme fire-weather conditions, when fire intensity is greater. After burning, stands remain vulnerable to future fires, until trees grow large enough to modify fuel levels and reduce stand flammability.

Benchmarks of fallen timber and man's role in nature: Some evidence from eucalypt woodlands in southeastern Australia

Fallen timber is widely considered to be a key element of ecosystem structure and function that is critical to maintenance of biodiversity. This concept is closely linked to ideas of wilderness and old growth. ‘Conventional wisdom’ is that fallen timber has been drastically depleted from natural levels by human activity. However natural conditions reflect interactions of Aborigines with their environment, and fallen timber as well as broadcast fire was critically important to Aboriginal economies in the New World and Australia. Quantitative historical data are not available, so it is necessary to use qualitative historical information to describe natural loads and dynamics of fallen timber. A comparison against detailed historical descriptions of woodlands under Aboriginal management in Australia indicates that benchmarks from ‘undisturbed’ examples of the same types of vegetation are generally inflated. The ecological history of grassy woodlands since European settlement shows that proposed ‘restoration’ measures will favour common and widespread biota at the expense of rare and endangered species. No correlation of biodiversity with fallen timber has been demonstrated for grassy eucalypt ecosystems. Globally, conservation strategies that minimize human activity have generally failed because resilience of ecosystems and ancient trees has been reduced and rare species have been lost. The concept of wilderness has little application outside the unpeopled continent of Antarctica.

A novel association between oribatid mites and leafy liverworts (Marchantiophyta: Jungermanniidae), with a description of a new species of Birobates Balogh, 1970 (Acari: Oribatida: Oripodidae)

AbstractThis paper contains a description of a new species of oribatid mite, Birobates hepaticolus sp. nov., from eucalypt woodland and rainforest in North Queensland, Australia. Adults and immatures of B. hepaticolus live completely enclosed within the ventral lobules of the corticolous liverwort Frullania ferdinandi‐muelleri Steph. The ventral lobes provide a protected, moisture‐buffered microhabitat on tree bark that would otherwise be subject to extremes of wetting and drying. Analysis of gut contents indicates that B. hepaticolus appears to feed on liverwort tissue. To our knowledge this is the first documented example of an association between an oribatid mite and a leafy liverwort based on the provision of food and habitat. The genus Birobates is redefined and diagnosed.

Life-form species–area relationships in a temperate eucalypt woodland community

Viewing species–area curves in the context of the different life forms that generate them might be instructive for understanding why high species density develops in some plant communities. In order to evaluate the patterns of species density in an Australian temperate eucalypt woodland community, we used species–area curves and document rate of species accumulation by life forms in six nested plots ranging in size from 1 m2 to 0.1 ha at 13 woodland sites. Mean total species density was 82 ± 3.8 species at 0.1 ha scales (range 49–104 species), making them amongst the most diverse woodlands in Australia at these spatial scales. Species–area relationships for total species were best described by power function models (log–log linear) with slopes (z) ranging from 0.12 to 0.35 (mean = 0.17 ± 0.02). When species were analysed by life form, species–area relationships were similarly well-described by the power function for all life forms, although their slopes differed significantly; annuals had the lowest slope and woody species the highest. Annuals and perennial herb species density were equal at the smallest spatial scales (mean 11.7 and 11.5 species/m2, respectively) and hence, both life forms help generate high small scale species density. Small-scale total species density, but not individual life form, was a significant predictor of larger-scale total species density (r 2 = 0.36, P = 0.03). Our findings suggest that high species density may be a general property of temperate eucalypt woodlands with herbaceous understoreys and that the mechanisms that underpin these patterns require further study.

Patterns of plant abundances in natural systems: is there value in modelling both species abundance and distribution?

In plant ecology it is common to use biophysical models to predict species distribution; however, spatial quantitative models of plant species remain rare. In practice, occupancy models are often assumed to indicate habitant quality and are used as surrogate abundance models. This study assessed the potential value of quantitative models of plants for ecosystem management applications by assessing patterns of occupancy and abundance within two closely related understorey plant species, Xanthorrhoea australis and X. caespitosa. Vegetation quadrats were surveyed in Eucalyptus woodland and cover-abundances were assessed using a metric pin intersection technique. A zero inflated generalised additive modelling process was used to assess the relationship of species occupancies and cover-abundances to environmental properties. The models were applied to mapped environmental data to create spatial predictions of occupancy and cover-abundance. Both species shared several predictor variables, but differing responses to these variables resulted in mutually exclusive distributions. No significant correlation was observed between occupancy and cover-abundance for X. australis, but strong correlation was evident for X. caespitosa. The strength of the occupancy and abundance relationship was found to differ greatly between the two species and is therefore likely to be species specific. Occupancy models have been used successfully as proxies for habitat quality models of plant species; however where occupancy and abundance of plants are driven by different influences occupancy will be a poor surrogate for abundance. Outcomes may be improved if occupancy models are validated for abundance or quantitative models are developed and tested for individual species.

After the fence: vegetation and topsoil condition in grazed, fenced and benchmark eucalypt woodlands of fragmented agricultural landscapes

Emerging ecological theory predicts that vegetation changes caused by introduction of livestock grazing may be irreversible after livestock are removed, especially in regions such as Australia that have a short evolutionary exposure to ungulate grazing. Despite this, fencing to exclude livestock grazing is the major tool used to restore vegetation in Australian agricultural landscapes. To characterise site-scale benefits and limitations of livestock exclusion for enhancing biodiversity in forb-rich York gum (Eucalyptus loxophleba Benth. subsp. loxophleba)–jam (Acacia acuminata Benth.) woodlands, we compared 29 fenced woodlands with 29 adjacent grazed woodlands and 11 little-grazed ‘benchmark’ woodlands in the Western Australian wheatbelt. We explored the following two hypotheses: (1) fencing to exclude livestock facilitates recovery of grazed woodlands towards benchmark conditions, and (2) without additional interventions after fencing, complete recovery of grazed woodlands to benchmark conditions is constrained by ecological or other limits. Our first hypothesis was supported for vegetation parameters, with fenced woodlands being more similar to benchmark woodlands in tree recruitment, exotic plant cover, native plant cover, native plant richness and plant species composition than were grazed woodlands. Further, exotic cover decreased and frequency of jam increased with time-since-fencing (2–22 years). However, we found no evidence that fencing led to decline in topsoil nutrient concentrations towards concentrations at benchmark sites. Our second hypothesis was also supported, with higher topsoil nutrient concentrations and exotic plant cover, and lower native plant richness in fenced than in benchmark woodlands, and different plant species composition between fenced and benchmark woodlands. Regression analyses suggested that recovery of native species richness is constrained by exotic species that persist after fencing, which in turn are more persistent at higher topsoil nutrient concentrations. We conclude that fencing to exclude livestock grazing can be valuable for biodiversity conservation. However, consistent with ecological theory, additional interventions are likely to be necessary to achieve some conservation goals or to promote recovery at nutrient-enriched sites.

Restore and sequester: estimating biomass in native Australian woodland ecosystems for their carbon-funded restoration

In the south-western region of Australia, allometric relationships between tree dimensional measurements and total tree biomass were developed for estimating carbon sequestered in native eucalypt woodlands. A total of 71 trees representing eight local native species from three genera were destructively sampled. Within this sample set, below ground measurements were included for 51 trees, enabling the development of allometric equations for total biomass applicable to small, medium, and large native trees. A diversity of tree dimensions were recorded and regressed against biomass, including stem diameter at 130 cm (DBH), stem diameter at ground level, stem diameter at 10 cm, stem diameter at 30 cm, total tree height, height of canopy break and mean canopy diameter. DBH was consistently highly correlated with above ground, below ground and total biomass. However, measurements of stem diameters at 0, 10 and 30 cm, and mean canopy diameter often displayed equivalent and at times greater correlation with tree biomass. Multi-species allometric equations were also developed, including ‘Mallee growth form’ and ‘all-eucalypt’ regressions. These equations were then applied to field inventory data collected from three locally dominant woodland types and eucalypt dominated environmental plantings to create robust relationships between biomass and stand basal area. This study contributes the predictive equations required to accurately quantify the carbon sequestered in native woodland ecosystems in the low rainfall region of south-western Australia.

Habitat use and trophic structure in a microbat assemblage on the edge of the southern rangelands, Western Australia: insights from stable isotope analysis

The microbat assemblage on Charles Darwin Reserve was investigated between 2007 and 2009 to provide a benchmark for monitoring long-term responses to climate change on a major bioregional boundary, the mulga–eucalypt line. Stable isotope analysis of bat fur was used to interpret the current local habitat and trophic relationships between microbat species with different biogeographical affinities. The stable isotope values of the ants inhabiting 10 broad vegetation types were used to provide an isotopic baseline of the Reserve to assist in the interpretation of the δC or δN signatures observed in the bat assemblage. The δC signatures of ants in both a Salmon Gum woodland and an arid shrubland shifted significantly after the breaking of a prolonged drought but there was no change in the bats. The ubiquitous bat species, and those with south-western affinities, probably used most of the available vegetation types on the Reserve and displayed some significant differences in mean trophic level. Scotorepens balstoni, a species of the southern interior of Western Australia, specialised at foraging within patches of eucalypt woodland. Vespadelus baverstocki, a southern arid zone species, was evidently restricted to the proximal arid habitats with distinctively high δN signatures.

Increased grazing and dominance of an exotic pasture (Bothriochloa pertusa) affects vertebrate fauna species composition, abundance and habitat in savanna woodland

The invasion of exotic pasture species into intact woodlands has the potential to affect native fauna by altering habitat structure and ecosystem function. The spread of these weeds is generally in concert with cattle grazing, so that fauna or habitat change is due to multiple interrelated causes. In this study we investigated whether the spread of the introduced pasture grass Bothriochloa pertusa and replacement of the native bluegrass B. ewartiana in eucalypt woodlands of northern Queensland has had an effect on terrestrial vertebrate fauna. We located 40 sites that sampled a range of native and introduced pastures cover, and investigated the spatial pattern of abundance with canonical analysis of principle coordinates, and correlation of the habitat attributes on the ordination space. We then selected a subset of four habitat attributes (eliminating highly colinear variables) and modelled species response to each using an information-theoretic approach. Thirty-one species (26 birds, one mammal and four reptiles) and two summary variables (bird abundance and richness) had best subset Akaike Information Criteria models with reliable parameters estimates. Seventeen models contained the B. pertusa frequency term and a further 16 had a term relating to upper storey cover (tree cover >10, 5–10 or 3–5 m). Though pasture grass cover, grazing and habitat features were correlated and thus we cannot ascribe B. pertusa as the sole determinant of fauna species change, this study has demonstrated that tropical savanna woodlands with changing Bothriochloa dominance from native to introduced species have different fauna species composition. In particular bird species richness, ground nesting species (e.g. rufous songlark Cincloramphus mathewsi, golden-headed cisticola Cisticola exilis) and terrestrial reptiles (e.g. Carlia munda and Ctenotus taeniolatus) declined. Disturbance-tolerant species such as Australian magpie Cracticus tibicen and yellow-throated miners Manorina flavigula increased in abundance in exotic pasture-dominated sites. As pastoral intensification continues in northern Australian rangelands there is a potential for significant change in the relative abundance and composition of vertebrate fauna and the reduction or loss of some species in the landscape.

Are invasive ants better plant‐defense mutualists? A comparison of foliage patrolling and herbivory in sites with invasive yellow crazy ants and native weaver ants

Benefits arising from facultative mutualisms between ants and plants vary with the identity of the ant partner. Invasive and native ants are both attracted to plants that offer extrafloral nectar, but few studies have compared their abilities to displace herbivores and benefit plants. Yellow crazy ants Anoplolepis gracilipes have invaded eucalypt woodlands of Arnhem Land, northern Australia, where they displace the native dominant weaver ant Oecophylla smaragdina. We compared the plant defense services provided by A. gracilipes and O. smaragdina ants on trees with (Acacia lamprocarpa) and without (Eucalyptus tetrodonta) extrafloral nectar rewards through surrogate herbivore (termite) addition experiments and surveys of herbivore damage. Anoplolepis gracilipes were more likely than O. smaragdina to discover termites on A. lamprocarpa, but the likelihood of termite discovery on E. tetrodonta did not vary with ant species. Anoplolepis gracilipes were also more thorough in their attacks of termites, recruited 3.4–4 times more workers to termites, and were 3.4 times quicker at discovering termites on A. lamprocarpa than were O. smaragdina. Discovery of termites by other predators did not vary significantly between trees in A. gracilipes and O. smaragdina sites. Herbivory scores did not reflect the foliage patrolling pattern by the ants. Old A. lamprocarpa leaves and both new and old leaves and branches on E. tetrodonta in A. gracilipes sites had higher chewing herbivory scores than their counterparts in O. smaragdina sites. Our results reveal that the more aggressive and efficient foliar patrolling by A. gracilipes does not translate to increased plant protection. Ant invasions can disrupt native ant–plant mutualisms despite invasive ants possessing many traits associated with effective plant guarding.

Do landscape health indices reflect arthropod biodiversity status in the eucalypt woodlands of eastern Australia?

Ecosystem or landscape health indices are important tools for land managers.While strong predictable relationships between these indices and biotic diversity are often generalized, they are seldom validated. Here we use data from a semi-arid eastern Australian woodland to examine the relationships between arthropod community structure and two sets of landscape health indicators: landscape function analysis (LFA), and a terrestrial index of ecological integrity based on common vegetation metrics (structure, composition and function; SCF). Hierarchical partitioning revealed that the ability of LFA or SCF to account for variation in arthropod richness was low, with the variable of importance taxon-dependent. Similarly, multivariate analyses indicated relatively weak and incon- sistent relationships between LFA and SCF indices and arthropod assemblage structure. Results obtained for additional habitat attributes commonly used in terrestrial vegetation monitoring were similar. Our study indicates that strong predictable relationships are rarely apparent, particularly for arthropods. This indicates that these indices have limited use as surrogates of arthropod biodiversity. These results are contrary to the past literature, highlighting the need for additional research and the development of a conceptual and empirical framework linking health indices and arthropod biodiversity.This is necessary to further the theoretical and practical application of these measurements in environmental management.

Comparison of Post‐mining Rehabilitation with Reference Ecosystems in Monsoonal Eucalypt Woodlands, Northern Australia

Rehabilitation of post‐mining lands frequently aims to create “self‐sustaining” systems. Where native vegetation is the designated post‐mining land use, it is generally assumed that rehabilitation that is similar to local native ecosystems is more likely to be sustainable. I compared landscape functionality, plant community composition, and vegetation structure in (1) reference sites representing pre‐mining native forest; (2) reference sites representing potential landscape analogues for the post‐mining landscape; and (3) a 23‐year chronosequence of post‐mining rehabilitation on the Weipa bauxite plateau, Cape York Peninsula, Australia. The trends across the post‐mining chronosequence indicate that vegetation growth is rapid in the first 5–8 years, and then slows with mean height approaching an asymptote after approximately 15 years. Landscape function indices showed a response that coincided with vegetation growth. Vegetation composition was significantly different from reference native forest. Most importantly, from the perspective of creating self‐sustaining ecosystems, the contribution of local framework species to vegetation in rehabilitation was significantly lower than in reference native forest. I discuss the results in relation to theoretical models of succession and conclude that without management intervention, differences between post‐mining rehabilitation and native forest are likely to be persistent.

Modelling fallen branch volumes in a temperate eucalypt woodland: implications for large senescent trees and benchmark loads of coarse woody debris

AbstractFallen branches are a substantial component of coarse woody debris and a key ecological resource. The depletion of stocks of coarse woody debris since European settlement has contributed to the degradation of Australian grassy box woodlands, including the loss of biodiversity. Restoration options for remnant woodlands include the augmentation of coarse woody debris stocks. However, the extensive modification of grassy box woodlands has left few reference sites for establishing benchmarks to guide such restoration. In this paper we demonstrate a method for predicting fallen branch debris loads in the absence of reference sites, using data from a yellow box–red gum woodland. Our methodology is in two stages: first, the total volume of branch debris under individual trees was modelled; and second, these models were applied to groups of trees to predict stand‐level loads of fallen branch debris. Although the models were developed for yellow box–red gum woodlands, the methodology would be applicable to other communities that lack reference sites. Predicted benchmark loads of fallen branch debris for yellow box–red gum woodland were between 7.0 m3 ha−1 and 11.9 m3 ha−1. Large senescing trees contributed the bulk of fallen branch debris. Model predictions indicated a 100‐cm diameter at breast height (dbh) tree was 10 times more likely to produce debris than a 50‐cm dbh tree, and if debris was present a 100‐cm dbh tree produced approximately 10 times the volume of branch debris produced by a 50‐cm dbh tree. These results highlight the importance of large senescing trees for the production of fallen branch debris and support the keystone role of large trees within remnant woodlands, and the need to conserve these structures. Our results also support the active management of regrowth woodland stands to facilitate the progression of individual trees to maturity and senescence. In particular, thinning of regrowth stands may promote the growth of retained trees, ensuring they contribute to fallen branch debris stocks with a minimum time lag.

Evaluating the Demographic, Reproductive, and Genetic Value of Eucalypt Paddock Trees for Woodland Restoration in Agricultural Landscapes

Eucalypt woodlands have been extensively cleared in southern Australia for agricultural production and the scattered trees that remain (“paddock trees”) are at risk of extinction without conservation action to lift recruitment rates. Here we assessed the reproductive, demographic, and genetic structure of trees from two vegetation types (paddock vs. intact vegetation fragments) for each of two species of eucalypts to characterize post‐clearance population structure and to evaluate paddock trees as seed sources for revegetation. Paddock trees of both species were structurally larger than trees in vegetation fragments, but seedlings and saplings were completely absent in paddocks due to ongoing agricultural land use. Eucalyptus leucoxylon paddock trees had high mortality, but overall paddock trees were not in poorer condition than fragment trees. E. leucoxylon paddock trees had lower reproductive output than trees in fragments, and Eucalyptus camaldulensis paddock trees had higher. Levels of genetic diversity of adult trees were very similar in the two vegetation types, and there was no genetic differentiation between paddock trees and remnant vegetation across our survey sites. These results suggest that paddock trees represent a potential source of seed to contribute to genetically diverse woodland restoration plantings, though further trials will be required to evaluate seedling survival on agriculturally modified land and under predicted future climate conditions.

Palatability mapping: a koala's eye view of spatial variation in habitat quality

Ecologists trying to understand the value of habitat to animals must first describe the value of resources contained in the habitat to animals and, second, they must describe spatial variation in resource quality at a resolution relevant to individual animal foraging. We addressed these issues in a study of koalas (Phascolarctos cinereus) in a Eucalyptus woodland. We measured beneficial and deterrent chemical characteristics as well as the palatability of trees using a near-infrared spectroscopic model based on direct feeding experiments. Tree use by koalas was influenced by tree size and foliar quality but was also context-dependent: trees were more likely to be visited if they were surrounded by small, unpalatable trees or by large, palatable trees. Spatial autocorrelation analysis and several mapping approaches demonstrated that foliar quality is spatially structured in the woodland at a scale relevant to foraging decisions by koalas and that the spatial structure is an important component of habitat quality.