Austral Ecology最新文献

Modelling the distribution of microendemic species presents significant challenges due to limited occurrence records and the coarse resolution of available bioclimatic data. This is particularly true for montane regions, which harbour high levels of endemism and environmental heterogeneity. In this study, we modelled the potential distribution of Brachycephalus pernix group toadlets to assess their range and identify key environmental drivers of their ecological niches. We applied two correlative modelling approaches—model-selection procedures using MaxEnt and Ensemble Small Models—incorporating a broad suite of environmental predictors beyond traditional bioclimatic variables. Our results highlight that Ensemble Small Models outperformed model-selection procedures (MaxEnt) in predicting suitable habitats for these microendemic species, yielding more spatially precise predictions centred in highland, montane and submontane regions. Suitability was strongly associated with environmental variables related to precipitation and moisture, which play a critical role in shaping the realised niche of the B. pernix group. The species exhibited niche conservatism, likely reflecting the retention of ancestral ecological preferences that facilitate persistence in montane environments. This supports the hypothesis that mountain ranges act as long-term refugia during climatic fluctuations. Importantly, models incorporating heterogeneous environmental data outperformed those using only bioclimatic variables, highlighting the value of accounting for topographic and climatic complexity when modelling narrow-range taxa. Despite identifying additional suitable habitats, many of these areas remain unprotected and are increasingly threatened by deforestation and land-use change. Our findings provide new insights into the ecological requirements and distribution dynamics of the B. pernix group and emphasise the urgent need for targeted conservation efforts to safeguard their specialised habitats and ensure long-term persistence.

Effective population monitoring programmes rely on identifying individual animals accurately and ethically without negatively impacting their natural behaviour and survival. This study aimed to determine if the chin scale patterns of the threatened yakka skink (Egernia rugosa) could be used to consistently identify individual skinks. We examined the pattern uniqueness by monitoring (1) juveniles within the same aggregation, (2) juveniles across aggregations and (3) all ages caught across all years. Finally, we trialled the utility of the process by testing 14 experienced and 14 inexperienced people to see if they could correctly identify recaptured lizards from different age cohorts and aggregations, and the timeliness of undertaking manual identification. We identified 377 individual skinks over the length of the study using their unique chin patterns. Juvenile skinks both from the same and different aggregations had unique chin patterns allowing individuals to be correctly identified. A total of 190 skinks (50.4%) were recaptured. Chin pattern stability was confirmed by the recapture of 76 sub-adult skinks between 2021 and 2023 during a period where the skinks had undergone a substantial increase in body size. Pattern stability was also recorded in 43 mature skinks that were recaptured over an extended period of 1–15 years (mean 4.9 years). Experienced and inexperienced volunteers successfully identified known individuals 96.5% and 97.6% of the time, respectively, and importantly, the level of experience did not influence the time required by participants to make an accurate identification. Natural chin scale pattern variation was shown to be an effective and efficient means to identify individuals of this species. Natural pattern variation should be considered a reliable alternative to more invasive reptile marking procedures (e.g., toe clipping) and for use with other reptiles with natural and stable scale pattern variation.

Australia's vast network of inland wetlands attracts thousands of waterbirds to congregate and breed during ‘boom’ periods of rainfall and productivity. Monitoring waterbird biodiversity predominantly relies on annual aerial and ground-based surveys, which may miss rare or elusive species of conservation importance. Environmental DNA (eDNA) metabarcoding is being increasingly used as a tool for rapid biodiversity assessments across a wide range of ecosystems. Before eDNA can be routinely applied to new ecosystems, assays need to be optimised to address several challenges, including primer bias, reference database limitations, and data curation strategies. Here, we used an eDNA assay to detect avian species at four inland wetlands in south-eastern Australia. We assessed the impact of filtering strategies on waterbird detection probabilities and compared results against historical observational survey records. Our eDNA assay identified up to 40% of waterbirds historically recorded at the sites. Waterbirds detected with eDNA included the elusive and endangered Australasian bittern, migratory species such as gull-billed tern and whiskered tern, and an introduced feral goose not previously recorded. Community composition varied with filtering and detection approaches, highlighting the importance of assessing the impact of data curation on species detection with respect to historical species records. This study demonstrates the potential for eDNA to be incorporated into waterbird monitoring programmes. Future research should prioritise improving reference databases and optimising field sampling protocols for these ecosystems.

Species interaction networks are expected to vary following temporal changes in the environment and the composition of the local community. However, there are still gaps in our knowledge about temporal variation in networks in tropical areas, where less variable climates are expected to produce more stable community structures over time. Here we describe a plant-hummingbird network in the Brazilian Campo Rupestre ecosystem and investigate multiscale temporal variation of interactions in this community as well as the possible mechanisms underlying the frequencies of species interactions. Plants visited by hummingbirds were observed monthly for a year and each species had morphology, phenology and nectar traits measured. During 624 h of observation we recorded nine hummingbird species visiting 47 plant species, amounting to 9015 visits to flowers. Most plants (28 species) were endemic to the Campo Rupestre and mostly visited by the also endemic hummingbird Augastes scutatus (the Hyacinth Visorbearer). The annual network was not nested but presented high modularity and intermediate specialisation. While the overall (annual) frequencies of interaction were primarily defined by morphological matching and phenological overlap, we found a remarkable temporal change in community structure over the year, with different processes underlying interactions among plants and hummingbirds at different seasons. The interaction pattern during the rainy season was more similar to the annual network than the dry season (when nectar sugar content and plant phenology were also important), with more links per species and lower specialisation. The higher importance of morphology to predict interactions during the rainy season suggests higher niche partitioning when more hummingbird species are present in the community. Our results exemplify the importance of considering the temporal dynamics of the community to advance the understanding of the processes defining species interactions over time in the tropics.

Lianas (woody vines) contribute substantially to tropical forest functioning, including carbon cycling, which makes accurate estimates of their biomass essential. Here, we aimed to quantify the contribution of lianas to biomass and stem density in disturbed Australian tropical forests. First, we destructively sampled lianas from the Wet Tropics World Heritage Area of northeast Queensland to develop an allometric equation to estimate liana above-ground biomass (AGB) from stem diameter. We then compared the accuracy of this equation for estimating liana AGB to previously published equations developed elsewhere. Using data from 17 vegetation plots (20 × 20 m) across the Cassowary Coast Region, we calculated liana contribution to biomass using our new equation. Based on RMSE and concordance correlation coefficient (CCC), our allometric equation performed better than those previously published (RMSE = 5.46, CCC = 0.94). Liana AGB estimates using our equation were lower than those based on previously published equations by at least 14%, suggesting that lianas have a lower AGB per unit stem diameter in our study region. Frequent cyclones and past logging may have led to numerous liana stems that are damaged, deformed, or stunted due to a lack of tall trees. We found that lianas contributed ~10% of woody biomass and 36.5% of woody stem density, which rose to 58% if climbing monocots were also included. When compared to liana studies conducted elsewhere, these forests are at the upper end of the range for documented liana densities worldwide. Our findings highlight the importance of developing regional allometric equations for estimating liana biomass. This work also underscores the need for continued measurement and monitoring of lianas to better understand how tropical forests respond to disturbance and global changes.

We monitored ground-layer vegetation in permanently marked plots in a temperate grassy woodland/sclerophyll forest mosaic, after the removal of sheep, but with continuing macropod grazing. Data collection over 15 years encompassed extremes of drought and high rainfall. Plots were stratified to sample 13 subhabitats reflecting variations in vegetation type and landscape position. Species composition varied with: (i) site productivity (grassy vs sclerophyll forest), (ii) soil moisture (landscape position) and (iii) presence of tree canopies in open grassland. After 15 years, most subhabitats retained their distinctiveness, with net changes suggestive of nutrient decline under tree canopies and increasingly mesic conditions on higher slope positions. Analysis of species richness of 18 origin and life-form groups over time revealed three types of responses: (i) stable, (ii) linear increase and (iii) a quadratic response. The latter was identified for native and exotic species in all habitats, specifically for annuals and short tussocks. There were sustained linear increases in the species richness of three native life forms (geophytes, subshrubs and leafy herbs) suggesting improvements in conservation status, while most native perennial groups were stable. Large perennial native grasses (Themeda triandra, Rytidosperma pallidum, Poa sieberiana and Aristida ramosa) maintained their initial dominance, while that of Lomandra filiformis and Melichrus urceolatus increased. The level of dominance of exotics was largely sustained, although exotic annuals fluctuated in response to seasonal conditions. The frequency of exotic perennial dicots increased slightly, despite intensive control efforts. We attribute the persistence of biomass under severe drought to the high dry matter content of many ground-layer dominants, which served to protect soil and provide refuge to palatable geophytes and native herbs. Our findings are consistent with ecological models that predict that cessation of fertiliser inputs and heavy livestock grazing will promote vegetation with ecosystem attributes resistant to climate extremes.

Australian peat-forming wetlands are some of the most biodiverse in Oceania. King Island, the second largest offshore island from mainland Tasmania, has the largest Ramsar-wetland area in Tasmania—the Lavinia State Reserve (LSR). The reserve has been under threat of peat loss from swamps over past decades due to wildfires, deforestation and drainage. To provide a framework and baseline to assess the resilience or susceptibility to future climate change and fire impacts at the LSR, we apply a palaeoecological approach to understand Holocene peat dynamics in two different LSR wetlands. This contributes to resolving the dynamics and rate of peat loss, thereby assisting in prioritising areas for further swamp conservation actions. Both LSR wetlands were once lakes, and peat accumulation only started due to terrestrialisation during a period of low water levels and drought in the Mid-Holocene. Fires have resulted in the loss of at least 4000 years' worth of accumulated peat in the largest peat-forming swamp, with the greatest loss likely linked to summer fires in the LSR in the 2000s. This finding shows the long-term vulnerability of the LSR wetlands to climate and fire impact, underscoring the need for effective fire management to conserve the remaining peat through fire control and careful hydrological management.

The successful restoration of disturbed ecosystems depends on the ability of below-ground soil decomposer communities to cycle organic matter into soil stocks and available forms for above-ground producers. We investigated the interactions between forest disturbance history, coarse woody debris and leaf carbon-to-nitrogen ratio (C:N) and their impacts on biological activity in soil and litter within a rehabilitated rock spoil and adjacent undisturbed montane forest in Kosciuszko National Park, Australia. We measured rates of soil CO₂ efflux and leaf decomposition, two key measures of soil function, to determine whether proximity to coarse woody debris improved soil function in rehabilitated sites. Coarse woody debris was associated with increased CO₂ efflux and decomposition in the rehabilitated forest (28.1% and 12.6% increase, respectively), but not within nearby undisturbed forest. In the absence of coarse woody debris, leaf mass loss to decomposition was 84.2% lower in the rehabilitated forest compared to the reference forest. Leaf decomposition varied significantly depending on the species from which the litter derived and was greatest in green tea and eucalyptus litter, and least in rooibos tea, with the CWD and forest type effects being consistent among these. However, decomposition of leaf litter of native species did not conform to expectations; leaves with low C:N had lower, rather than higher, rates of decomposition. These findings highlight the positive effects of coarse woody debris addition on soil functioning within rehabilitated forests and its potential in reconstructing nutrient cycles following disturbance.