Austral Ecology最新文献

Ecologists strive to untangle the complex interplay of current and historical factors, along with evolutionary history of species, to understand communities’ structure. However, this can be achieved by integrating different approaches to expanding our knowledge about the underlying processes connecting assemble rules of ecological communities. In order to better understand how ecological and/or evolutionary factors may affect the structure of communities, we assessed the phylogenetic and functional structure of 33 tadpole communities in the Atlantic Forest Southeastern Brazil and tested whether phylogenetic conservatism drives tadpole traits. We identified 19 communities which were significantly phylogenetic clustered and 10 which were significantly functional clustered. Trait diversity was skewed towards the root, indicating phylogenetic trait conservatism as an important driver of the structure of tadpole communities. The best explanatory model of the phylogenetic diversity included, in order of importance, presence of potential fish predators, water conductivity, external diversity of vegetation structure, canopy cover, internal diversity of vegetation structure and dissolved oxygen. Most variables were negatively correlated with phylogenetic diversity, but the presence of potential fish predators was positively correlated. For functional structure, external diversity of vegetation structure, canopy cover, area, dissolved oxygen and presence of potential fish predators were selected as the best explanatory model (presented in order of importance). Furthermore, of the 10 functionally structured communities, eight were also phylogenetically structured. In this sense, environmental variables could be filtering tadpole lineages interacting with phylogenetically conserved species traits, thus driving anura tadpole species’ occurrence on communities. Our study provides evidence that anuran communities structure results from interacting ecological and evolutionary processes.

If palaeoendemic invertebrates depend on palaeoendemic plants, and the latter are threatened by an increase in fire incidence, there is a possibility of an extinction cascade. We test whether there is co-occurrence of palaeoendemic plants and invertebrates in the proximity of a 52-year-old fire boundary in subalpine Tasmania, Australia. We used 2 × 2 m quadrats to record the incidence and cover of vascular plants and trapped invertebrates at each of these 33 sites in six time periods using an alpine Malaise trap and a CD sticky trap. The number of co-occurrences of palaeoendemic plant taxa with palaeoendemic invertebrate taxa was greater than expected by chance (p = 0.020), but many palaeoendemic invertebrates co-occurred with non-palaeoendemic plants. Some of the palaeoendemic invertebrate taxa that were associated with palaeoendemic plants were monophagous, while others were associated with environmental conditions created by a long absence of fire. Many may be threatened if increasing fire incidence destroys vegetation dominated by palaeoendemic plants.

Riparian taxa are subject to dynamic, intense, flood-related stressors, and have evolved traits to persist in this environment. Climate change-induced intensification of flood regimes pose a threat to these ecosystems, and little is understood about their resilience to this intensification. Following two consecutive major floods (the first flood record-breaking) along the subtropical coast of eastern Australia in March 2022, we used methods based on persistence (resprouting, seedling recruitment), and floristic structure (height, DBH) and assemblage, to assess the resilience of an old growth riparian rainforest to severe flooding in the 12-month post-flooding window. Smallerwoody plants (stems <10 m tall, <30 cm DBH) were the most impacted and were significantly impacted by flooding. Native species richness and plant density (plants/m⁻²) significantly decreased between before and 3 months post-flooding, after which they continued to significantly increase to surpass pre-flood values. Overall, ~35% of taxa exhibited resprouting, ~28% of taxa exhibited seedling recruitment, and ~11% exhibited both resprouting and recruitment. An additional ~21% native taxa were introduced to the site via seedling recruitment, along with 65 invasive species. Model-based multivariate analysis showed flooding significantly altered community floristics (p = 0.026) at 3 months. At 12 months post-flooding the community was recovering, becoming more floristically similar to its pre-flood composition. The riparian rainforest exhibited high resilience to intense flooding. Impact, persistence, and resilience varied amongplots, and the community took 12 months to move into recovery. We found that persistence, and floristic structure and composition weighted against impact were effective measures of ecosystem resilience. In the absence of further consecutive events, mature-phase riparian rainforests are likely to be structurally and floristically resilient to climate change-induced amplification of flood regimes. Further studies should build on this framework to include invasive weed species impacts, for a more accurate assessment of impacts.

Microclimate, such as soil and surface air temperatures, and edaphic factors, such as soil organic matter content and nutrient availability, are important parameters of the below-canopy environment that shape vegetation communities. Yet, the literature examining how microclimate and edaphic properties vary along elevation gradients in tropical rainforests is limited, hindering our understanding of key ecological processes in the forest understory. Here we present an analysis of high-resolution (15-min frequency) microclimate data spanning approximately 3 years (December 2019–September 2022) across 20 rainforest sites, ranging from 40 to 1550 meters above sea level (a.s.l.). We also present analyses of soil chemical properties, including δ¹⁵N isotope composition from the same study sites. Our study found soils were consistently cooler than air during the day and warmer than air during the night across all sites. The difference in mean temperature between the wettest (summer) and the driest (winter) quarter for both soil and air also increased with elevation, as did the annual temperature range. Soil organic matter content and C:N ratio increased with elevation, in concert with a decline in soil pH. Together, edaphic factors displayed a strong correlation with climatic factors, suggesting temperature as an important driver of soil properties across elevation. Finally, soil δ¹⁵N was found to decline with increasing elevation, suggesting a tighter N cycle in high elevation, higher organic matter soils. These observations highlight the existing elevational trends in both microclimate and edaphic variables in the Australian Wet Tropics; understanding how these trends may shift with climate change could be important for predicting impacts on species distributions.

Crabs are fundamental in coastal ecosystems due to their role in nutrient cycling, habitat structuring, population control and as indicators of environmental health. Investigating the size distribution and life stages of these species is crucial for understanding their ecology and designing effective conservation strategies. This study provides data on the distribution and stage ratios of two populations of local species of the genus Cyrtograpsus (Decapoda: Brachyura: Varunidae) in the Playa Cangrejales intertidal. These endemic species had not been previously described in the study area, highlighting the need for further research in the future. Three surveys were conducted from December 2019 to February 2020, following a transect perpendicular to the coast, obtaining two series of data (C-I and C-II). Specimens were identified, sexed and measured in situ for subsequent release. A total of 1099 individuals were counted, identifying Cyrtograpsus affinis (C-I = 278; C-II = 332) and Cyrtograpsus angulatus (C-I = 215; C-II = 277), with a higher proportion of C. affinis. The presence of these species at Playa Cangrejales coincides with the geographical distribution reported in the literature, although the proportions differ from those reported for other Argentinean beaches. The most frequent lengths were equal to or less than 10 mm cephalothorax length (±1 mm). The maximum lengths reported in the literature for each species were not recorded. For C. angulatus, juveniles always predominated over adults and recruits. C. affinis showed fluctuations between adult and juvenile proportions in the upper and middle zones, with adults predominating in the lower zone during December and February. Juveniles occupied all mesolittoral floors, whereas adults were more frequent in the middle and lower floors. This information is essential to develop management tools to protect these species and their environment. The division between stages was realized following criteria from the literature. Analyses and interpretations were made using data distribution and frequency graphs.

Southeast Australian saltmarshes are endangered ecological communities under threat from various anthropogenic factors including climate change. As climate change drives sea-level rise mangrove encroachment and saltmarshes are squeezed at their landward edge, our lack of knowledge of the ecological interactions and any associations between saltmarsh vegetation and fauna becomes concerning, especially given the importance of saltmarsh for fisheries and as a blue carbon habitat. This study investigated the association of saltmarsh vegetation and the abundance and movement of gastropods in a typical coastal saltmarsh at Patonga, New South Wales, Australia. Densities of the gastropods including Phallomedusa solida, Ophicardelus spp. and Littoraria luteola were significant in vegetated Salicornia quinqueflora and least in unvegetated saltmarsh and areas where mangroves had encroached. Experiments that translocated Ophicardelus spp. and manipulated cover revealed that these patterns were actively maintained by Ophicardelus spp., which dispersed up to 40 cm and 1.4 m after 3 and 24 h, respectively, away from unvegetated saltmarsh and mangroves. The results of this study suggest that both habitat and cover influence the abundance and movement of gastropod dynamics in southeastern saltmarsh. Given future anticipated saltmarsh loss, further investigations are needed on the unknown functional role of gastropods in saltmarsh ecosystems.

The sungazer (Smaug giganteus) is a strict grassland specialist lizard endemic to South Africa's highveld grasslands. It is currently listed as Vulnerable (IUCN) and is primarily threatened by anthropogenic activities. Because sungazers are habitat specialists, climate change may be detrimental to the species, considering their life-history traits, and the area of available suitable habitat. We assessed how climate change may impact the sungazers' geographic range by first producing an ecological niche model (ENM) for the species within a buffered region of its extent of occurrence (buffered EOO). The ENM was then projected to 2040, 2060, 2080 and 2100 under two climate change scenarios using Shared Socioeconomic Pathways (SSP); SSP245 (moderate-case) and SSP585 (worst-case). A mean ensemble of three global circulation models for each time period and scenario was used to create habitat suitability maps which were refined using a natural grassland variable overlay. Resulting maps were clipped to the sungazers' EOO and interpreted distribution. Within the interpreted distribution, models predicted an area of 10 198 km² of current suitable habitat. At this scale, future habitat suitability is predicted to remain relatively stable (area: 9910 km²; 3% decline) under SSP245 by 2100. However, a 24% decline (area: 7705 km²) in habitat suitability was predicted under SSP585. Within the buffered EOO, habitat suitability increased in south-western regions, which was more prominent under SSP585. Although this finding suggests that sungazers could track favourable conditions, their life history and low dispersal ability makes climate tracking unlikely. Because sungazers only occur in primary grasslands, regions dominated by agricultural activities, further land use developments are likely to affect the species survival. Thus, careful conservation management is essential, and we recommend the establishment of protected areas with cognizance of our predictions for current and future suitable habitat within the sungazers' interpreted distribution.

Prescribed burning is frequently used in savanna vegetation in Australia and worldwide. In north-east Queensland savanna burning has been proposed for the control of woody weeds including Cryptostegia grandiflora (rubbervine), an invasive shrub/vine of riparian savanna. However, burning as a management tool can have non-target impacts on ecosystems, particularly where associated with additional invasive species, such as the exotic stoloniferous grass species Bothriochloa pertusa (Indian couch). For this reason, an experiment was established to test for non-target impacts of prescribed burning on herbaceous vegetation. The experiment consisted of wet and dry season burning, and single and double burning treatments during a 4 year study. Annual herbaceous surveys were conducted, both before treatments applied, and then annually. We addressed alternative hypotheses, that (i) burning would exacerbate grazing impacts resulting in negative outcomes for native herbaceous vegetation, or alternatively (ii) burning would be neutral or beneficial to native herbaceous assemblages due to savanna co-evolution with fire. Burning treatments resulted in subtle but beneficial responses for native herbaceous vegetation. Native legume biomass, percent composition and percent frequency, and forb species richness, increased 4–5 months following wet season burning with above average rainfall. There was a delayed (8–18 months) positive response of burning (both wet and dry season) in percent composition of native grazing sensitive perennial grasses. There was a slight short-term decline in introduced perennial grass percent composition and biomass following treatment. Results were consistent with predominantly positive or neutral responses to prescribed burning. There was no evidence to support the hypothesis that invaded native savanna herbaceous assemblages declined with burning treatment applications. These results are discussed in relation to other savanna studies in northern Australia and to the role of fire in the maintenance of herbaceous vegetation in savanna biomes.

Altered fire regimes and the increased frequency and/or severity of wildfires are significant issues for fire-sensitive species. In the Austral summer of 2019/2020, Australia experienced one of the worst fire seasons in recorded history (known as the 2019/2020 megafires), affecting 12.6 million hectares of eastern Australia. The Endangered southern greater glider (Petauroides volans) inhabits large areas impacted by the 2019/2020 megafires. With increasing fire severity, frequency, and intensity, there is a need to understand where in the landscape southern greater gliders are most impacted by fire, and where the species is most likely to persist in fire-affected landscapes. This is challenging given the lack of systematic data collected for this species. Maximum entropy modelling (Maxent) is a type of species distribution model with good predictive performance for presence-only records. We used Maxent to model the distribution of the southern greater glider in the two years prior (2017–2019) and two years post (2020–2022) megafire across the East Gippsland region of Victoria, an area heavily affected by the 2019/2020 megafires. Whilst we found that the predicted short-term area of occurrence of the southern greater glider remained relatively stable in the two years after megafire, a large area of marginal habitat was considerably reduced. We interpret this result as a potential contraction of suitable habitat where southern greater gliders may become isolated. Post fire, higher elevation areas and locations that experienced comparatively lower fire severity and a lower fire frequency had a higher predicted occurrence of the southern greater glider. Understanding the role of fire in species survival is essential for effective biodiversity conservation and management of species. More comprehensive and systematic monitoring in suitable and unsuitable areas will enhance our understanding of the distribution of the southern greater glider, including areas subject to wildfire.