Brigalow Belt Research Articles

Fine‐scale quantification of floral and faunal breaks and their geographic correlates, with an example from south‐eastern Australia

AbstractAim We introduce a method to quantify shared breaks in aggregate biotic distributions and their relationships to geographic variables. The method is based on quantification of distributional taxic and abiotic data that can be applied over multiple spatial scales. We aim to show biogeographic breaks and varying transition zones at a fine level of detail (5‐km resolution) and develop an approach to assess existing bioregionalization schemes.Location Global applicability, using an example from New South Wales in south‐eastern Australia.Methods Moving window analyses, rotated in 15° increments through 360°, are used to assess the degree of anisotropic spatial turnover between sets of gridded cells containing georeferenced species observations. Patterns of biotic turnover are compared with equivalent analyses for elevation and lithology. Identified breaks are assessed against an existing bioregionalization scheme (Interim Biogeographic Regionalisation of Australia, IBRA).Results There was fine‐scale concordance between turnover patterns and several IBRA bioregions. Breaks in turnover of flora and fauna corresponded with the boundaries of the Hunter Valley and Sydney Basin regions, particularly the boundary between the Brigalow Belt South and Sydney Basin. Low‐turnover zones were quantified; prominent examples are the Sydney Cataract and Wyong bioregions. Turnover along many boundaries was gradational, confirming that mapped breaks are not abrupt. A previously unidentified break was identified in the South East Corner bioregion. Spatial turnover patterns were similar between biota and were reflected in mean correlation coefficients between turnover in each group: mammals–reptiles (r = 0.70, P << 0.01); mammals–flora (r = 0.56, P << 0.01); and reptiles–flora (r = 0.51, P << 0.01). Generally, patterns of abiotic turnover reflected biotic turnover, although mean turnover correlations were weaker than between biota.Main conclusions Using this method we were able to characterize taxic breaks and overlaps in detail and at a spatially fine resolution. For our study region, we confirm the overall integrity of the IBRA framework, but suggest that it may benefit from revision in some respects.

Ecohydrological feedback as a land restoration tool in the semi-arid Brigalow Belt, QLD, Australia

In this study of native plant communities in the Brigalow Belt – a semi-arid bioregion of Queensland and New South Wales, Australia – an ecohydrological model was designed to investigate the complex feedback relationships existing between plant community traits and soil water dynamics among post-disturbance (i.e. mining and agricultural) landscapes. Two distinct locations (having similar composition and climatic environment, yet different soil water dynamics) were selected to compare the interaction and sensitivity of these traits towards water evaporation from soil or from plant transpiration. The model is constrained by soil physical attributes and climate data monitored at the Brigalow Catchment Study, and plant community parameters were derived using Latin hypercube sampling and pattern oriented modelling.Our findings indicate that, under the given soil–climate constraint, plant communities could only thrive if they were able to avoid prolonged periods of water stress (e.g., by minimising their physiological wilting point). Further, the influence of vegetation dynamics on evaporation from soil was deemed to be critical for the simulated soil water dynamics, whereas plant transpiration affected soil moisture only marginally.Moreover, both monitoring sites were dominated by the same species but co-dominated by different tree species, suggesting that evaporation from soil was probably influenced by the co-dominant species, whereas transpiration was probably controlled by the dominant species.For the re-establishment of native plant communities on post-mined landscapes and for agro-forestry and resource management in the Brigalow Belt, this implies that inherent ecosystem processes exist, which control plant community development and, hence, ecohydrological functions such as regulation of evapotranspiration.Therefore, restoration strategies should carefully reflect on species composition and their ecohydrological functions rather than attempting to re-establish the pre-disturbance ecosystem form and function – which could be less robust and even unsuccessful given post-disturbance conditions and under altered soil conditions of post-mined landscapes or the uncertainty of future climatic environments.

A revision of Strophurus taenicauda (Squamata; Diplodactylidae) with the description of two new subspecies from central Queensland and a southerly range extension

The Golden-tailed Gecko, Strophurus taenicauda (De Vis 1886), is redescribed and two new subspecies from centralQueensland are diagnosed on the basis of scalation, colour pattern and genetic differences. The distribution of S. t. taeni-cauda comprises the south-eastern part of the Queensland Brigalow Belt bioregion. Strophurus taenicauda albiocularisssp. nov. occupies the northern half of the range whilst S. taenicauda triaureus ssp. nov. has a limited range in the centraleastern part of the Brigalow Belt. The two new subspecies are predominantly inhabitants of Eucalyptus woodlands andare not as restricted to Brigalow (Acacia harpophylla) woodlands as S. t. taenicauda. A single record of the nominate subspecies from northern New South Wales is also reported, extending the range of the species by >250km.

Effects of local-scale management on herbaceous plant communities in Brigalow ( Acacia harpophylla) agroecosystems of southern Queensland, Australia

Remnant vegetation in agricultural landscapes is assumed to contain the majority of biodiversity, although few Australian studies have considered the contribution made by the surrounding production matrix. In this study, herbaceous plant communities from Brigalow ( Acacia harpophylla) remnants and adjoining areas of the matrix were sampled to determine differences in plant species composition at the core and edge of four distinct land management categories. Nineteen sites consisting of Brigalow remnant and adjacent matrix were selected in the Brigalow Belt Bioregion of southern Queensland, Australia. This region has undergone recent agricultural development relative to the older, well studied landscapes of western Europe. Edge and core transects in four different land management categories were sampled for herbaceous plant species richness, composition and cover. Brigalow remnants contained significantly higher mean herbaceous richness than all other land management categories, and cultivated areas contained the lowest. Species richness, cover and composition did not differ between previously cultivated and uncultivated grasslands. Unlike other studies, there were no detectable edge effects for plant species richness, herbaceous cover and composition in any of the land management categories. Biodiversity conservation in agricultural landscapes in Australia should maintain a focus on the remnant vegetation components; however, our results suggest that there is the potential for enhancing plant biodiversity and ecological functioning by targeted management in modified grassland communities. Management and restoration efforts to conserve agroecosystem plant biodiversity should therefore integrate a range of different landscape elements.

Unusual patterns of tooth wear among koalasPhascolarctos cinereusfrom St Bees Island, Queensland, require re-evaluation of criteria for aging koalas by tooth-wear class

Tooth wear patterns among P. cinereus on St Bees Island in the humid Central Queensland Coast bio geographic region differ significantly from those observed in the sub-humid Brigalow Belt bio geographic region. Within the Brigalow Belt region, tooth-wear patterns among P. cinereus at Biloela, Springsure and Oakey are similar. The published method for the estimation of age based on tooth-wear from P. cinereus populations at Springsure and Oakey is applicable to the Biloela population but is not applicable to the St Bees Island population. It is concluded that, in Queensland at least, the tooth wear - age class classification should be verified with local data when applied in environments different from those of the Brigalow Belt. Further, the appropriateness of using a single tooth-wear classificatory scheme to establish the age of P. cinereus for transfer overseas is questioned.

Goethe's “Delicate Empiricism”: Assessing its Value for Australian Ecologists

AbstractJohann Wolfgang von Goethe, recognised as a seminal German polymath, developed a unique approach for investigating nature, termed “delicate empiricism”. Goethe's approach uses empathy, imagination and intuition to promote a participatory engagement with the world. It goes beyond the dualistic-rationalism that defines “conventional” ecological research and can lead to novel insights. “Delicate empiricism” was applied in an ecologically-degraded agricultural landscape in the Brigalow Belt, Queensland, Australia, and its potential for increasing landscape understanding and providing a basis for land-use design was assessed. It was found that Goethe's approach led to holistic, qualitative landscape awareness, not ordinarily accessible via “conventional science”. Application of “delicate empiricism” also gave rise to a land-use design that refected the Australian-nessof the Brigalow Belt landscape, particularly the potential for recovery of native biodiversity values through retention of regrowth vegetation. Overall, the study suggested that there is merit in educating Australian ecologists about “delicate empiricism” to encourage more creative and sensitive landscape management, that is in sync with the environment.

Application of the survey protocol for chytridiomycosis to Queensland, Australia

Spread of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis, has resulted in the extinction of frogs, but the distribution of Bd is incompletely known. We trialled the survey protocol for Bd by attempting to systematically map its distribution in Queensland, Australia. Bd was easily detected in known infected areas, such as the Wet Tropics and South East Queensland. It was not detected in bioregions adjacent to, but inland from or to the north of, infected regions: Einasleigh Uplands and Cape York adjacent to the infected Wet Tropics; and Brigalow Belt South adjacent to the infected South East Queensland bioregion. These regions where Bd was not detected have bordered infected regions for between 15 yr (in northern Queensland) and 30 yr (in southern Queensland), and so they define the geographical limits of Bd with regard to the long-term environmental conditions in Queensland. The Gulf Plains, a bioregion distant from infected bioregions, was also negative. Bd was confined to rainforest and bordering habitats, such as wet eucalypt forests. Infections were largely confined to permanent water-associated species, consistent with this being an important cause of this group having the greatest declines. Our data supports biogeographic climatic models that show much of inland and northern Australia to be too hot and dry to support Bd. As there is limited opportunity for Bd to spread further in Queensland, the priority for management is reducing the impact of Bd in affected populations and assisting frogs to disperse into their former distributions. Given that the survey protocol has been applied successfully in Australia it may be useful for mapping the distribution of Bd in other parts of the world.

Vegetation succession and recovery of ecological values in the southern Queensland Brigalow Belt

Summary Broadscale land‐clearing in the Queensland Brigalow Belt has resulted in widespread decline in ecological values including biodiversity loss and impairment of ecosystem processes and functions. More than 90% of brigalow ecological communities, i.e. those that have Acacia harpophylla, F. Muell. ex Benth (Brigalow) as a dominant and co‐dominant, have been entirely cleared or severely degraded in recent decades. In spite of this wide‐ranging disturbance, partial ecological recovery may be possible in the Queensland Brigalow Belt through the retention of regrowth brigalow stands. Few studies, however, have quantitatively examined brigalow vegetation succession, particularly in the context of cost‐effective ecological restoration. This study used a chronosequence approach to examine how species richness, abundance and structure change in brigalow woodlands with years since clearing. Floristic and structural characteristics were surveyed in 18 brigalow stands, of varying years since clearing, in the southern Queensland Brigalow Belt. Linear models were fitted for years since clearing versus total number of woody species, tree cover, shrub cover, herbaceous cover and litter cover. Regrowth brigalow communities were found to follow the inhibition model of succession, with Acacia harpophylla assuming dominance. The linear models suggested that at least 90 years of recovery would be required post‐clearing, before regrowth woodlands regained 90% of the species richness and structural characteristics of mature woodlands. Management practices such as thinning the dominant species and allowing for the accumulation of logs and litter may be necessary for promoting recovery of vegetation diversity and structural heterogeneity.

Effects of forest management on structural features important for biodiversity in mixed-age hardwood forests in Australia's subtropics

The contiguous forest landscapes of the Brigalow Belt Bioregion in Australia's subtropics, known as ‘the western hardwood forests’ are thought to be important for biodiversity conservation through the provision of continuous habitat features in an otherwise extensively cleared region. However, these forests have a long management history, as they are also important for timber production and stock grazing. Knowledge of the effect of these and other disturbances on the distribution and abundance of key structural or habitat features are limited and forest management activities thus continue uninformed. To address this knowledge gap, we investigated the effects of prescribed and non-prescribed disturbances on the distribution and abundance of six key habitat features (live and dead trees with hollows, large mature live trees, shrub abundance, downed coarse woody debris and litter cover) at 120 sites located in spotted gum Corymbia citriodora dominant forests within the western hardwoods.Logged stands had a lower mean abundance of live trees with hollows (2.5±0.6ha−1) than unlogged stands (6.2±0.8ha−1). This is below current timber harvesting prescriptions which outline the retention of 6 live trees with hollows ha−1. Since only 13.5% of western hardwood forest under state forest tenure remains unlogged, live trees with hollows are currently limited throughout the majority of the western hardwood forests. Recent wildfire in the region also meant reduced numbers of live trees with hollows. Logging affected the abundance of large, live trees, with highest densities occurring in the less intensively logged stands. Given the close relationship between increased tree diameter and hollow occurrence across a number of tree species, the small area of unlogged forest remaining in the region suggests that the pool of trees that may eventually form hollows may also be limited. The density of dead trees with hollows was strongly reduced by fire; by both low-frequency but high-intensity fires (wildfire) and by high-frequency but low-intensity burns associated with stock grazing management. Increased grazing was also associated with decreased abundance of shrubs and less downed coarse woody debris. Other than decreasing with increased logging intensity, litter cover did not appear to be influenced by other disturbance regimes, at least not by the long term correlational approach of our investigation. Overall, our results suggest that although forest management in the western hardwood forests could currently be described as low-intensity, it is extensive and impacts are discernible and cumulative. We highlight the need for a landscape approach to be taken in managing the various land uses for both production and biodiversity within the contiguous western hardwood forests.

Impacts of grazing, selective logging and hyper‐aggressors on diurnal bird fauna in intact forest landscapes of the Brigalow Belt, Queensland

AbstractThe impact of forest management on diurnal bird assemblages and abundance was investigated in contiguous tracts of eucalypt forest in the Brigalow Belt Bioregion, south central Queensland. Sites were located across three levels of livestock grazing intensity and three levels of selective logging intensity within the most extensive habitat type, Corymbia citriodora‐dominant forest. We recorded a high rate of incidence and large numbers of the hyper‐aggressive noisy miner Manorina melanocephala (Passeriformes: Meliphagidae) at the majority of our survey sites, a phenomenon rarely reported in non‐cleared landscapes. As shown by numerous studies in fragmented landscapes, the distribution of this species in our study had a substantial negative effect upon the distribution of small passerine species. Noisy miners exerted the strongest influence upon small passerine abundance, and masked any forest management effects. However, key habitat features important for small passerines were identified, including a relatively high density of large trees and stems in the midstorey. Selective logging appeared to exert a minimal effect upon noisy miner abundance, whereas grazing intensity had a profound, positive influence. Noisy miners were most abundant in intensively grazed forest with minimal midstorey and a low volume of coarse woody debris. Higher road density in the forest landscape also corresponded with increased numbers of noisy miners. Reduction in grazing pressure in Brigalow Belt forests has the potential to benefit small passerine assemblages across large areas through moderating noisy miner abundance. The strong relationship between noisy miners and small passerines suggests that noisy miner abundance could act as an easily measured indicator of forest condition, potentially contributing to monitoring of forest management outcomes.

Taxonomy, ecology, genetics and conservation status of the pale imperial hairstreak (Jalmenus eubulus) (Lepidoptera:Lycaenidae): a threatened butterfly from the Brigalow Belt, Australia

The taxonomic status of Jalmenus eubulus Miskin stat. rev. is revised and considered to be specifically distinct from J. evagoras (Donovan) based on fundamental differences in morphology, ecology and genetics. Miskin’s holotype is fixed by monotypy and illustrated, with type locality Rockhampton, Queensland. Fixed differences in the mitochondrial genomes of J. eubulus and J. evagoras in which the mean pairwise divergence is only 0.85% indicate absence of matrilineal gene flow, whereas allozyme data show significant structure within and between populations of both species consistent with recent diversification. Underlying causes for the observed genetic patterns are investigated. The two species are parapatric, with a narrow range of overlap along the Great Escarpment in south-eastern Queensland. Jalmenus eubulus is restricted to vegetation communities comprising brigalow-dominated old-growth open-forests and woodlands in the Brigalow Belt (with larvae monophagous on Acacia harpophylla F. Muell. Ex Benth), whereas J. evagoras occurs in a range of disturbed eucalypt woodlands/open-forests predominantly in montane and coastal areas east of this bioregion (with larvae polyphagous on Acacia species other than A. harpophylla). The conservation status of J. eubulus is considered to be vulnerable nationally and critically endangered in New South Wales according to International Union for Conservation of Nature (IUCN) criteria. Nationally, the geographic range has an estimated area of occupancy of less than 2000 km2, is severely fragmented, and the extent or quality of its habitat, which is poorly conserved, continues to decline. It is recommended that the taxon be used as an indicator for identification of remnant old-growth forest for conservation planning, as well as a flagship for the conservation of invertebrate biodiversity associated with this threatened ecological community.

What influences farmers to keep trees?: A case study from the Brigalow Belt, Queensland, Australia

Landscape change is driven by economic, demographic and cultural factors operating at a range of spatial and temporal scales. However, landscapes developed for agriculture often retain some wooded areas or paddock trees. The study aimed to identify the relationships between, and influence of, the demographic, economic and cultural values of landholders on the retention of native trees on farms in the Brigalow Belt, Queensland. Two response variables were tested: the proportion of total tree cover on all soil types, and the proportion of tree cover on fertile soils most suitable for agriculture. Explanatory variables were grouped into five conceptual areas: economic factors, demographic characteristics, cultural/social values, attachment to property, and opinions about vegetation management control. Principal components analysis and generalised linear models were used to select and assess the influence of the explanatory variables. An economic factor, farm size, had the strongest influence on both response variables, although the effect was less strong for tree cover on fertile soils. Agreement that tree cover was attractive (a cultural value) and attendance on training courses (a demographic characteristic) were also influential, together with other economic factors recognising production benefits from wooded areas. We conclude that a better understanding of social, economic and cultural factors that influence landholders’ decisions about how much tree cover to retain on their property is a prerequisite to targeting passive landscape restoration in areas where over-clearing is threatening landscape health.

Roads, fire and aggressive competitors: Determinants of bird distribution in subtropical production forests

Forestry practices such as fuel-reduction burning and maintenance of road networks can negatively impact avian assemblages, both directly by changing habitat structure and indirectly by creating conditions favorable for predators or competitors. The Brigalow Belt forests include some of the largest contiguous areas of native forest in the temperate and sub-humid zones of eastern Australia. Over 1 million ha of these forests are proposed to be converted from forestry to conservation tenure, yet the impacts on the avifauna of current and potential future forest management practices are not known. We investigated the influence of road edges and habitat type and structure on the avifauna of a 356 000 ha forest. Survey sites were either <50 m or >300 m from a road, and in either cypress pine Callitris glaucophylla forest, spotted gum Corymbia citriodora forest with a regenerating cypress pine/buloke Allocasuarina luehmannii understorey or spotted gum forest with an open understorey due to fuel-reduction burning. The avifauna differed significantly among vegetation types but not with proximity to a road, with the greatest differences between cypress pine and both types of spotted gum forest. The noisy miner Manorina melanocephala, an aggressive avian competitor, appears to be the factor mediating these assemblage-level differences. Noisy miners were rare in cypress pine forest but were three times more numerous than any other species in spotted gum forest. Spotted gum forest with a regenerating understorey had fewer noisy miners. Although total bird abundance was highest in open spotted gum forest, the species richness and abundance of passerines smaller than noisy miners was significantly lower in this forest type. Abundance of small passerines was eight times higher in sites where <3 noisy miners were recorded. Only one species, the eastern yellow robin, was influenced by proximity to a road edge. Cypress pine forest is potentially an important refuge for smaller birds. The results suggest that burning regimes that reduce regeneration of the cypress pine and buloke subcanopy in spotted gum forest potentially are exacerbating the problem of noisy miner domination of the avifauna.

Monitoring continental movement patterns of the Australian Bustard Ardeotis australis through community-based surveys and remote sensing

Many birds of Australia's arid and monsoonal regions are characterized by dispersive or nomadic movements and large population fluctuations in response to variable climatic conditions. These characteristics, compounded by our generally limited knowledge of bird movements and population dynamics (in part due to limited research effort in these sparsely-populated rangelands), complicate population monitoring and conservation for such species. Here we employ mail surveys of landholders across continental Australia to assess the distribution and movement patterns of the Australian Bustard Ardeotis australis. We combine data from these simple mail surveys with more sophisticated techniques that allow for tracking the flux in rainfall patterns and vegetation greenness over broad spatial and temporal scales, to identify and describe the responses of bustards to seasonai and climatic variability. Our results demonstrate that residency patterns of bustards vary widely across Australia. The seasonality of bustard occurrence is generally more pronounced in regions characterized by predictable seasonal conditions. Seasonal patterns are also evident in more climatically unpredictable regions, although here they may be increasingly overlaid by more idiosyncratic movements as a result of longer term variation in rainfall and associated patterns of primary productivity. We found limited evidence that bustards respond to inter-regional irregularities in rainfall events, suggesting that nomadic movements are generally not continental, but rather intra-regional. However, longer term data sets that cover several more, or more extreme, climatic fluctuations than that considered here, are needed to assess these relationships adequately. To a lesser degree and differently between regions, respondents reported that bustards are also associated with fire, grasshopper outbreaks, crop agriculture and drought. They are most abundant across the savannahs of northern Australia extending to parts of the Pilbara and recently cleared regions of the Brigalow Belt in eastern Queensland. In southern Australia, bustards are perceived as shor-term, irregular visitors whereas more permanent populations persist in northern and northeastern regions. While there are inherent limitations to such data, the study illustrates the utility of incorporating rangeland users into the types of large-scale monitoring programmes required to assess the distribution and movement patterns of highly mobile birds or species characterized by large population fluctuations.

Analysis of multi-date MISR measurements for forest and woodland communities, Queensland, Australia

Many theoretical and applied studies have demonstrated that the anisotropic reflectance of the land surface is determined by the structural and optical properties of the land surface. The Multi-angle Imaging SpectroRadiometer (MISR) measures the anisotropic reflectance of the land surface thus has the potential to improve the operational mapping of canopy attributes in Queensland, one of the largest states in Australia. The aim of this study was to assess the relationship between foliage projective cover (FPC) and the shape of the bidirectional reflectance distribution function (BRDF) for a mixed grassland/woodland ecosystem, the Southern Brigalow Belt Biogeographic Region. A practical approach for deriving the surface bidirectional reflectance factor (BRF) from MISR “Local" mode data using existing MISR products is presented. The BRDF typology of the land surface was determined using shape parameters derived from inversion of the linear Ross–Thick Li–Sparse Reciprocal and the non-linear Rahman–Pinty–Verstraete (RPV) models against a time series of MISR “Local" mode surface BRF data. Following an evaluation of the models inversion error, the RPV model was examined for correlation with FPC, a canopy attribute routinely derived from Landsat data in Queensland. Our empirical analyses showed the MISR derived RPV model parameters were qualitatively related to spatial and temporal variations in vegetation structure in Queensland and the k parameter contained information independent of FPC. These results are consistent with published findings from other regions.

Conservation planning with irreplaceability: does the method matter?

A number of systematic conservation planning tools are available to aid in making land use decisions. Given the increasing worldwide use and application of reserve design tools, including measures of site irreplaceability, it is essential that methodological differences and their potential effect on conservation planning outcomes are understood. We compared the irreplaceability of sites for protecting ecosystems within the Brigalow Belt Bioregion, Queensland, Australia, using two alternative reserve system design tools, Marxan and C-Plan. We set Marxan to generate multiple reserve systems that met targets with minimal area; the first scenario ignored spatial objectives, while the second selected compact groups of areas. Marxan calculates the irreplaceability of each site as the proportion of solutions in which it occurs for each of these set scenarios. In contrast, C-Plan uses a statistical estimate of irreplaceability as the likelihood that each site is needed in all combinations of sites that satisfy the targets. We found that sites containing rare ecosystems are almost always irreplaceable regardless of the method. Importantly, Marxan and C-Plan gave similar outcomes when spatial objectives were ignored. Marxan with a compactness objective defined twice as much area as irreplaceable, including many sites with relatively common ecosystems. However, targets for all ecosystems were met using a similar amount of area in C-Plan and Marxan, even with compactness. The importance of differences in the outcomes of using the two methods will depend on the question being addressed; in general, the use of two or more complementary tools is beneficial.

Cattle, crops and clearing: Regional drivers of landscape change in the Brigalow Belt, Queensland, Australia, 1840–2004

Landscape change occurs through the interaction of a multitude of natural and human driving forces at a range of organisational levels, with humans playing an increasingly dominant role in many regions of the world. Building on the current knowledge of the underlying drivers of landscape change, a conceptual framework of regional landscape change was developed which integrated population, economic and cultural values, policy and science/technology. Using the Southern Brigalow Belt biogeographic region of Queensland as a case study, the role of natural and human drivers in landscape change was investigated in four phases of settlement since 1840. The Brigalow Belt has experienced comparable rates of vegetation clearance over the past 50 years to areas of tropical deforestation. Economic factors were important during all phases of development, but the five regional drivers often acted in synergy. Environmental constraints played a significant role in slowing rates of change. Temporal trends of deforestation followed a sigmoidal curve, with initial slow change accelerating though the middle phases then slowing in recent times. Future landscape management needs to take account of the influence of all the components of the conceptual framework, at a range of organisational levels, if more ecologically sustainable outcomes are to be achieved.

Conservation of Endangered Grasslands in the Brigalow Belt: Are Things Looking up for Bluegrass Downs?

Conservation of Endangered Grasslands in the Brigalow Belt: Are Things Looking up for Bluegrass Downs?

Vine Thicket Communities of the Brigalow Belt Bioregion of Queensland

Vine Thicket Communities of the Brigalow Belt Bioregion of Queensland

Organic carbon partitioning in soil and litter in subtropical woodlands and open forests: a case study from the Brigalow Belt, Queensland

A woodland–open forest landscape within the Brigalow Belt South bioregion of Queensland, Australia, was surveyed for soil organic carbon, soil bulk density and soil-surface fine-litter carbon. Soil carbon stocks to 30 cm depth across 14 sites, spanning a range of soil and vegetation complexes, ranged from 10.7 to 61.8 t C/ha, with an overall mean of 36.2 t C/ha. Soil carbon stocks to 100 cm depth ranged from 19.4 to 150.5 t C/ha, with an overall mean of 72.9 t C/ha. The standing stock of fine litter ranged from 1.0 to 7.0 t C/ha, with a mean of 2.6 t C/ha, and soil bulk density averaged 1.4 g/cm3 at the soil surface, and 1.6 g/cm3 at 1 m depth. These results contribute to the currently sparse database of soil organic carbon and bulk density measurements in uncultivated soils within Australian open forests and woodlands. The estimates of total soil organic carbon stock calculated to 30 cm depth were further partitioned into resistant plant material (RPM), humus (HUM), and inert organic matter (IOM) pools using diffuse mid-infrared (MIR) analysis. Prediction of the HUM and RPM pools using the RothC soil carbon model agreed well with the MIR measurements, confirming the suitability of RothC for modelling soil organic carbon in these soils. Methods for quantifying soil organic carbon at landscape scales were also explored, and a new regression-based technique for estimating soil carbon stocks from simple field-measured soil attributes has been proposed. The results of this study are discussed with particular reference to the difficulties encountered in the collection of the data, their limitations, and opportunities for the further development of methods for quantifying soil organic carbon at landscape scales.