Austral Ecology最新文献

Difficulty in detecting species' presence is a common issue when surveying threatened species. This is particularly relevant when target species occur in remote regions, have small populations, are difficult to detect, or sampling effort is limited. This can lead to underestimation of a species' true occurrence, which can be an issue where developments are proposed that could impact populations through habitat loss or fragmentation. We aimed to identify the environmental variables influencing the probability of detecting the magnificent broodfrog (Pseudophryne covacevichae), determine environmental triggers for survey initiation and estimate the number of surveys required to provide confidence in the species' true absence at a location. We analysed repeat site survey data from 13 locations where the species was known to occur. Single-season occupancy models identified volumetric soil moisture to be the most influential environmental variable in detection, followed by a combination of volumetric soil moisture and accumulated rainfall in the 5 days prior to a survey. These two variables were used to classify survey conditions into poor, average and excellent, defined by their 5th, 50th and 95th percentiles, to estimate the relationship between survey conditions and survey effort. Cumulative detection probability under ‘poor’ environmental conditions remained low, with less than 40% cumulative detection probability following six surveys and high uncertainty in posterior distributions. In contrast, under ‘average’ conditions, detection probability increased to 96% following three surveys, and in ‘excellent’ conditions, a single survey resulted in 98% probability of detection, and certainty in the posterior distributions increased in both instances. These results demonstrate that targeting surveys under good to optimal environmental conditions can improve detection probability, maximise the efficiency of surveys and reduce the likelihood of false absences.

Habitat loss and fragmentation are leading threats to biodiversity and have been implicated in population declines worldwide. In agricultural landscapes where natural habitat has been extensively modified, remnant patches can preserve species richness and diversity. However, the persistence of some organisms is dependent on a species' ability to move between habitat patches. The effects of habitat loss and fragmentation on reptiles in semi-arid agricultural landscapes, and the relative impact of cropping and grazing, are poorly described. We aimed to investigate the effect of habitat fragmentation on semi-arid reptiles by comparing species richness and diversity between continuous habitat and patches embedded within different land use types (cropping and grazing). Reptiles were surveyed using pitfall traps, funnel traps and active searches across 20 sites stratified by site, vegetation and land use type. Twelve sites were established in remnant mallee woodland patches embedded within an agricultural matrix, and eight sites were established in a private conservation reserve on the same property. Generalised linear models were used to explore relationships between reptile species richness and diversity and design variables. A total of 480 individuals from 31 species were recorded. Reptile species richness was significantly higher in the reserve compared to patches. However, these differences were driven more by reductions in species richness in patches embedded within a grazing matrix, which had fewer species than patches embedded within a cropping matrix. Sites within sand plain vegetation had higher diversity than sites within dune mallee vegetation. Our findings suggest semi-arid reptile species are sensitive to habitat loss and fragmentation associated with land clearing. Therefore, protecting large areas of intact habitat on private property is required to maintain reptile diversity in semi-arid landscapes subject to land use change. Managing patches of remnant vegetation within the agricultural matrix through grazing exclusion may also serve to retain reptile diversity.

Grasslands are among the most utilised habitat types for livestock production and the least protected ecosystems globally. Livestock grazing alters the abiotic and biotic features of a landscape and influences vegetation structure. In turn, these vegetation structural changes can adversely impact native animals that use these habitats, including reptiles. The endangered pygmy bluetongue lizard (Tiliqua adelaidensis) exclusively inhabits livestock-grazed grasslands in South Australia. Using a before/after, control/impact design, we investigated the effects of short-term grazing exclusion on vegetation structure and lizard abundance across two sites with natural vegetation and climate variation. We found vegetation structure differed between the two sites in “before” and “after” data but did not detect any effect of grazing treatment. We detected a negative association of lizard abundance with tussock cover in “before” data and a negative association with bare ground in the “after” data at the more arid site (Peterborough), although there was no significant overall grazing exclusion effect on lizard abundance at either site. Our survey techniques at a site scale may not have captured microhabitat-scale changes that could have influenced pygmy bluetongue responses. This study indicates short-term and small spatial scale grazing exclusion will have non-significant effects on pygmy bluetongues. Sheep grazing management is an important component of pygmy bluetongue conservation, and we recommend further research to incorporate multiple spatial scales over a longer time prior to applying landscape management actions.

Fire is a critical driver of many Australian ecosystems, including the groundwater-dependent heathlands on Australia's east coast. However, the effects of intense wildfires under drought conditions, associated with depletion of groundwater and soil moisture, are poorly documented, and mechanisms of vegetation recovery, particularly for obligate seeders and resprouters, are unclear. We aimed to assess the impacts of an intense wildfire on vegetation structure and species composition in a long-unburnt groundwater-dependent heathland, focusing on the responses of obligate seeder and resprouter species and the role of environmental factors in post-fire recovery. A before–after control–impact study was conducted at Bribie Island, Queensland, following a 2019 wildfire. Vegetation responses were analysed using a generalised linear model, with environmental factors such as rainfall, soil moisture and groundwater levels evaluated for their influence on recovery. Our results demonstrated that shrub counts recovered and exceeded pre-fire levels within 3 years. Species richness returned to pre-fire levels after 2 years but did not reach the peak observed during high-moisture conditions 3 years before the fire. The post-fire response included a slow species richness rebound and incomplete recovery. Obligate seeders showed a variable response, with some dominant populations failing to recover, while resprouters exhibited significant declines. These outcomes are linked to the varying capacity of heathland flora to cope with intense fire during low soil moisture and groundwater deficits. The results of this study suggest that intense wildfires during dry conditions may adversely affect some obligate seeder and resprouter populations, even after long fire intervals. Full consideration of fire intensity, timing and environmental conditions such as soil moisture and groundwater levels are essential for effective vegetation management. Furthermore, prescriptive fire management should focus on burning during periods of high soil moisture to reduce fire severity and enhance post-fire regeneration.

Schoenefuss, P., Kutt, A.S., Kern, P.L., Moffatt, K.A., Bon, J., Wardle, G.M. et al. (2024) An Investigation Into the Utility of Eastern Barn Owl Pellet Content as a Tool to Monitor Small Mammal Diversity in an Arid Ecosystem. Austral Ecology, 49, e13503. Available from: https://doi.org/10.1111/aec.13503.

Figure 2 Depicts the dental structure of two example specimens to show the differences used to distinguish two genera. Images (c) and (d) are labelled incorrectly as Pseudomys sp. This specimen is a Leggadina sp. The wrong photo was selected (from a different study) when collating this figure. This is significant, because Leggadina is undetected in this study.

We have attached the correct image and caption below.

There is also a typo in the caption for Figure 2. “… and lower premolars (b) & (d)…” should be corrected to “… and lower molars (b) & (d)…”.

We apologise for these errors.