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Prescribed burning has been widely used in the management of forests for reducing wildfire risk, and can have significant effects on soil carbon (C) and nitrogen (N) pools and their temporal changes. This study aimed to investigate the impacts of different burning frequency regimes on the temporal dynamics of C and N in the topsoil and forest floors. The experimental site was a 39 year old wet scherophyll forest prescribed burning trial at Peachester, southeast Queensland, Australia, with treatments of no burning (NB) since 1969, 2 yearly burning (2yrB) and 4 yearly burning (4yrB) since 1972. Each of three burning treatments had four replications and these plots were randomly distributed over an area of the forest with similar vegetation and soil characteristics. Soil (0–10 cm) and forest floors were sampled monthly for 6 months prior to the next scheduled burning for both burning treatments to minimize the effects of fire recency. Prescribed burning significantly (P < 0.01) affected most C and N variables in both soils and forest floors. The 2yrB treatment had significantly lower (P < 0.01) soil total C, total C:N ratio, microbial biomass C (MBC) and N (MBN), MBC:MBN ratio, dissolved organic C (DOC) and N (DON), NO3−-N, inorganic N and L layer total N, DON and NO3−-N, compared with the NB and 4yrB treatments. However, there were no overall significant differences in these variables between the NB and 4yrB treatments. Sampling month significantly (P < 0.01) affected C and N variable in both soils and forest floors except for soil total C and N and F layer MBC. Temporal dynamics of most of these labile C and N variables were highly related to soil and forest floor moisture content, seven day mean air temperature (MAT) and cumulative rainfall prior to sampling date. However, fire effects were independent of sampling month, as there were no significant interactions between them for most response variables measured. This study has clearly demonstrated that more frequent burning (2 yr burning) had negative impact on soil and forest floor C and nutrient pools. Insignificant differences observed in soil C and N and forest floor N pools between less frequent burning (4yrB) and NB treatments highlighted that the prescribed burning at four year interval gave sufficient time for recovery of these soil and forest floor nutrients to pre-burn levels.

Cherax quadricarinatushas been widely translocated within Australia, and a number of self-sustaining feral populations have established, and persisted, in central-eastern Australia for over 20 years: however, the biology and ecology of feral populations remain poorly understood. Using the loss-by-ignition method, this study investigated differences in the total content of incombustible material (as a proxy for total mineral content), between feralC. quadricarinatuspopulations in southeast Queensland and northeastern New South Wales. A total of 102C. quadricarinatuswere ignited, and percent total incombustible material was not proportional to the body size, or gender of the crayfish. Incombustible content was however, significantly different between some locations of capture (i.e., waterbodies). The site where incombustible content in crayfish was atypical, Lake Ainsworth, is a naturally acidic coastal lake, and we suggest that acidity and low concentration of calcium in that waterbody are likely responsible for the difference in mineral content detected in that population. Mechanism(s) driving the difference detected in the Lake Ainsworth population are unknown, but we suggest the acidic environment could directly impact maintenance of internal calcium reserves in the crayfish (intermoult), during recalcification of the cuticle (postmoult), or both. Limited calcium availability in the lake may also be a direct, or indirect, contributing factor. The ability ofC. quadricarinatusto occupy acidic habitats while managing biomineralization challenges possibly could enable additional range-expansion of the species, and potential impacts on both endangered ecological communities and other biota occupying the acidic coastal habitats of Eastern Australia.

Prescribed fire is one of the most widely-used management tools for reducing fuel loads in managed forests. However the long-term effects of repeated prescribed fires on soil carbon (C) and nitrogen (N) pools are poorly understood. This study aimed to investigate how different fire frequency regimes influence C and N pools in the surface soils (0-10 cm). A prescribed fire field experiment in a wet sclerophyll forest established in 1972 in southeast Queensland was used in this study. The fire frequency regimes included long unburnt (NB), burnt every 2 years (2yrB) and burnt every 4 years (4yrB), with four replications. Compared with the NB treatment, the 2yrB treatment lowered soil total C by 44%, total N by 54%, HCl hydrolysable C and N by 48% and 59%, KMnO4 oxidizable C by 81%, microbial biomass C and N by 42% and 33%, cumulative CO2-C by 28%, NaOCl-non-oxidizable C and N by 41% and 51%, and charcoal-C by 17%, respectively. The 4yrB and NB treatments showed no significant differences for these soil C and N pools. All soil labile, biologically active and recalcitrant and total C and N pools were correlated positively with each other and with soil moisture content, but negatively correlated with soil pH. The C:N ratios of different C and N pools were greater in the burned treatments than in the NB treatments. This study has highlighted that the prescribed burning at four year interval is a more sustainable management practice for this subtropical forest ecosystem.

During revegetation, the maintenance of soil carbon (C) pools and nitrogen (N) availability is considered essential for soil fertility and this study aimed to evaluate contrasting methods of site preparation (herbicide and scalping) with respect to the effects on soil organic matter (SOM) during the critical early establishment phase. Soil total C (TC), total N (TN), hot-water extractable organic C (HWEOC), hot-water extractable total N (HWETN), microbial biomass C and N (MBC and MBN), total inorganic N (TIN) and potentially mineralizable N (PMN) were measured over 53 weeks. MBC and MBN were the only variables affected by herbicide application. Scalping caused an immediate reduction in all variables, and the values remained low without any sign of recovery for the period of the study. The impact of scalping on HWETN and TIN lasted 22 weeks and stabilised afterwards. MBC and MBN were affected by both herbicide and scalping after initial treatment application and remained lower than control during the period of the study but did not decrease over time. While scalping had an inevitable impact on all soil properties that were measured, that impact did not worsen over time, and actually improved plant growth (unpublished data) while reducing site establishment costs. Therefore, it provides a useful alternative for weed control in revegetation projects where it is applied only once at site establishment and where SOM would be expected to recover as canopy closure is obtained and nutrient cycling through litterfall commences.

Weed control is a key factor affecting early plant growth and establishment in revegetation projects in South-east Queensland of sub-tropical Australia. Costs associated with weed control are significant and methods which reduce establishment costs and effectively suppress weeds are of great interest. However, different methods may have implications for soil quality and fertility and require a detailed investigation. Understanding the response of soil organic matter (SOM) and microbial functional diversity to different weed control methods is crucial as they affect soil quality and nutrient availability. A field trial was established in South-east Queensland to identify the effects of three methods of weed control: (1) glyphosate, (2) a mixture of glyphosate and MCPA and (3) topsoil removal or scalping on SOM, microbial biomass, soil respiration, NH4+-N availability, potentially mineralisable N (PMN) and soil microbial community functional diversity (as assessed by carbon substrate utilisation using Biolog GN2 plates). The scalped area had lower SOM and microbial activity compared to the herbicide and control plots. There was no significant difference in water soluble organic carbon (WSOC), hot water extractable organic C (HWEOC), hot water extractable total N (HWETN) and microbial biomass C and N (MBC and MBN) between the herbicide and control plots, particularly at week 20. NH4+-N and PMN values were lower at week 20 than week 1 in the herbicide and scalping treatments. Week 20 was the end of the growing season and reduction in N availability may have been the result of decreasing temperature. Principal component analyses (PCA) from Biolog GN2 results indicated a separation in soil microbial community function in the scalped area compared to the other treatments which may have implications for soil properties in the long term. Scalping proved to be the most cost-effective method of site preparation, requiring fewer site visits for weed control compared to herbicide application. However, SOM was significantly affected by scalping due to topsoil removal and it may not be a sustainable practice in short rotation plantation establishment. Single herbicide application at field rates did not impact soil organisms but also failed to achieve proper weed control.

Purpose It is anticipated that global climate change will increase the frequency of wildfires in native forests of eastern Australia. Understorey legumes such as Acacia species play an important role in maintaining ecosystem nitrogen (N) balance through biological N fixation (BNF). This is particularly important in Australian native forests with soils of low nutrient status and frequent disturbance of the nutrient cycles by fires. This study aimed to examine 15N enrichment and 15N natural abundance techniques in terms of their utilisation for evaluation of N2 fixation of understorey acacias and determine the relationship between species ecophysiological traits and N2 fixation.

The aim of this paper was to relate anopheline mosquito longevity to malaria incidence in two areas in Indonesia: West Timor and Central Java. We estimated the physiological age of females captured landing on humans or resting inside and outside buildings. The estimate was based on the state of the ovaries and was used to estimate longevity. The results showed that there were large differences between the two areas surveyed. In West Timor the longevity of the anophelines ranged from 13 to 23 days, sufficient for completing the intrinsic incubation cycle and for malaria transmission, whereas in Central Java the longevity was only 3 days, insufficient both for incubation and for transmission. We concluded that the West Timor study area had a greater risk of malaria transmission than that of Central Java and this was supported by village survey data that showed greater malaria incidence in West Timor than in Central Java.

In addition to predicted changes in climate, more frequent and intense severe weather events (e.g. tropical cyclones, severe storms and droughts) have been identified as serious and emerging threats to the World's freshwater crayfish. This paper documents a single, high intensity rainfall event (in an area known for phenomenal rainfall events) that led to a flash flood and mass mortality of Euastacus valentulus in the Numinbah Valley of southeast Queensland in 2008. Several hundred crayfish died after evidently being swept away and entrapped in vegetation or buried in alluvium during this single extremely high flow event. In light of our observations, it is clear that severe weather events have the capacity to substantially impact/deplete freshwater crayfish populations. This emerging climate-driven threat is seen as particularly significant for freshwater crayfish species that occupy single localities with highly restricted ranges. Clarification of geographic ranges would allow a priority list of the most "at risk" populations, which could prove useful in a management response to severe weather events, which are predicted to be more frequent in future.

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.

In a search for potential biocontrol agents for Acacia melanoxylon R. Br. (Mimosaceae), larvae of the beetle Diplocoelus dilataticollis Lea (Coleoptera; Biphyllidae) were found within damaged seeds of A. melanoxylon. The gut contents of larvae and adults were examined to determine whether their diet included seeds, in apparent contradiction to the known mycophagous diet of members of this family of beetles. Calcofluor M2R White, a plant cell-wall staining optical brightener was used to differentiate between plant cell fragments and fungal tissue in the gut content smears. Gut contents of adults of a known seed predator of A. melanoxylon, a weevil of the genus Melanterius, were examined in the same way to provide a benchmark. The gut contents of D. dilataticollis differed from those of Melanterius sp. Fungal structures and microbes were found in the gut of D. dilataticollis, in contrast to plant cell fragments found in the gut of the weevil and from scrapes made directly from seeds. We conclude that larvae of D. dilataticollis feed primarily on fungi associated with damaged seed and therefore may not be the proximate cause of seed damage.

Identifying species groups is an important yet difficult task, with there being no single accepted definition as to what constitutes a species, nor a set of criteria by which they should be delineated. Employing the General Lineage Concept somewhat circumvents these issues, as this concept allows multiple concordant lines of evidence to be used as support for species delimitation, where a species is defined as any independently evolving lineage. Genetically diverse groups have previously been identified within the monotypic parastacid genusTenuibranchiurusRiek, 1951, but no further investigation of this diversity has previously been undertaken. Analysis of two mitochondrial DNA gene regions has previously identified two highly divergent groups within this taxon, representing populations from Queensland (Qld) and New South Wales (NSW), respectively. Additional testing within this study of both mitochondrial and nuclear DNA through species discovery analyses identified genetically diverse groups within these regions, which were further supported by lineage validation methods. The degree of genetic differentiation between Qld and NSW populations supports the recognition of two genera; with Qld retaining the original genus nameTenuibranchiurus, and NSW designated asGen. nov.until a formal description is completed. Concordance between the species discovery and lineage validation methods supports the presence of six species withinTenuibranchiurusand two withinGen. nov. The recognition of additional species removes the monotypy of the genus, and the methods used can improve species identification within groups of organisms with taxonomic problems and cryptic diversity.

We investigated the influence of native flora and fauna on the establishment and persistence of the exotic weed Ageratina riparia (Asteraceae) in disturbed and regenerating rainforests on the Springbrook plateau of south-eastern Queensland. The height and ground cover of A. riparia was positively associated with light availability beneath the rainforest canopy and negatively associated with forest leaf litter biomass. Regenerating rainforest with the associated increases in litter and decrease in light availability could therefore inhibit the establishment and density of A. riparia. The red-necked pademelon, Thylogale thetis, browsed extensively on A. riparia, but the pattern of browsing was not associated with light availability, forest leaf litter biomass or density of A. riparia. Browsing and incidental damage by T. thetis breaks up the broad stands of A. riparia. The physical damage caused by T. thetis, and the inhibition to establishment and density of A. riparia by native plant species, combine to reduce the environmental threat associated with A. riparia.

Projected elevations in environmental temperature are expected to have a detrimental effect on organisms with distributions that are already restricted to high-altitude refugia, especially where dispersal is compromised due to population isolation by unsuitable intervening habitats. The present study was carried out on such an organism, namely Euastacus sulcatus, to determine: (1) the temperature at which thermal stress occurs under laboratory conditions; and (2) whether thermal stress is already occurring naturally in contemporary field-acclimatised individuals. The laboratory data provided evidence that biochemical and physiological stress occurred in E. sulcatus at 22.5°C or higher. In the field, oxidative stress was characterised by an increase in the oxidised redox state of glutathione within a low-altitude population accompanied by significantly elevated protein carbonyls and lipid peroxidation. The data confirmed that potential thermal stress was present in E. sulcatus residing at the lower end of its altitudinal distribution, indicating that this threatened species is already challenged within localised populations in their natural environment. Together, these results reveal that future increases in environmental temperature are not only likely to result in increased baseline levels of stress in E. sulcatus, but also forecast further restriction in the altitudinal distribution of the species in a warming climate.

Rapid colour changes in vertebrates have fascinated biologists for centuries, herein we demonstrate dynamic colour change in an anuran amphibian, the stony creek frog (Litoria wilcoxii), which turns from brown to bright (lemon) yellow during amplexus. We show this by comparing the colour of baseline (unpaired males) and amplecting (paired) males. We also investigate the possible role of stress and stress hormones on this colour change. Frogs were subjected to four different levels of stressors (handling, toe-clipping, saline injection and adrenocorticotropic hormone [ACTH] injection) and the colour change was measured using digital photography. A comparison of baseline colour and stress hormone (corticosterone) levels was also conducted to give further insight to this topic. From the images, the Red Blue Green (RGB) colour values were calculated, and a principal components analysis (PCA) was used to create a single colour metric (the major axis) as an index of colour in the visible spectrum. A moderate stressor (toe-clipping) led to a significant change in colour (within 10 min) similar to that of amplecting males. Surprisingly, neither a mild stressor (handling and saline injection) nor the maximum stressor (handling and ACTH injection) led to a lightening response. This study confirms that the dynamic male colour change in this species in response to medium stressors adds new knowledge to the understanding of the functional mechanisms of dynamic colour change in amphibians.

Background Malaria is a serious health issue in Indonesia. Mosquito control is one aspect of an integrated malaria management programme. To focus resources on priority areas, information is needed about the vectors and their habitats. This research aimed to identify the relationship between anopheline mosquitoes and topography in West Timor and Java. Methods Study areas were selected in three topographic types in West Timor and Java. These were: coastal plain, hilly (rice field) and highland. Adult mosquitoes were captured landing on humans identified to species level and counted. Results Eleven species were recorded, four of which were significant for malaria transmission: Anopheles aconitus, Anopheles barbirostris, Anopheles subpictus and Anopheles sundaicus. Each species occupied different topographies, but only five were significantly associated: Anopheles annularis, Anopheles vagus and Anopheles subpictus (Java only) with hilly rice fields; Anopheles barbirostris, Anopheles maculatus and Anopheles subpictus (West Timor only) with coastal areas. Conclusion Information on significant malaria vectors associated with specific topography is useful for planning the mosquito control aspect of malaria management.

Increased temperature as a potentially threatening process, and the need to investigate the thermal tolerance of the ‘highland-rainforest’ Euastacus were first identified 20 years ago; however, the thermal repertoire of Euastacus has still not been explored. Euastacus is the largest of Australia’s 10 freshwater crayfish genera with 52 species, and includes many of the largest, slowest-growing and longest-lived species (some >35 years) in the World. Several species have distributions consistent with being ‘climate refugees’, namely, being closely associated with cool, damp conditions and restricted to isolated mountain-top refuges. The present study investigated the critical thermal limit of a well known abundant species, Euastacus sulcatus, from central eastern Australia. Thermal limit was assessed using chronic, ongoing exposure to steadily increasing temperature, with the breakdown of physiological function tested by righting response. Distress was clearly evident in the crayfish at ~23°C (e.g. sluggish, lack of aggression), and the test criterion was met at ~27°C, with animals effectively incapacitated and unable to right themselves. Field water temperatures rarely exceed 21°C; however, any increases in environmental temperature may expose this species to temperatures where physiological stress may become problematic.

Very high rates of extinction are recorded in freshwater ecosystems, with coastally distributed species threatened by urban development, pollution and climate change. One example, the world’s second smallest freshwater crayfish (genus Tenuibranchiurus), inhabits coastal swamps in central-eastern Australia. Although only one species is described (Tenuibranchiurus glypticus), it was expected that populations isolated through habitat fragmentation would be highly divergent. The aims of this study were to determine if populations of Tenuibranchiurus are genetically distinct, and if ancient divergence, as indicated in other species in the region, was evident. Tenuibranchiurus were collected at seven sites, extending the known geographical distribution ∼260 km south to Wooli, New South Wales. Analysis of two mitochondrial DNA gene regions indicated two highly divergent clades, with numerous additional subclades. Both clades and subclades were strongly congruent with geographical location, and were estimated to have diverged from each other during the Miocene or Pliocene era. Little sharing of haplotypes between subpopulations was evident, indicating negligible gene flow, and genetic differentiation between subclades possibly indicates distinct species. The coastal distribution of Tenuibranchiurus, severe habitat fragmentation and clear differences between subclades suggest that they should be recognised as evolutionarily significant units, and be treated as such if conservation and management initiatives are warranted.