Suchergebnisse

Context Fallen timber is a key habitat feature in forests and woodlands for vertebrate and invertebrate fauna, and is either consumed or left partially burnt after the passage of fire. This impact on habitat quality assumes significance because increasing areas of land are subject to frequent hazard-reduction burning and wildfire in eastern Australia. Aims We test here whether partially burnt or charred fallen timber is employed as habitat to the same extent as unburnt fallen timber. Methods Vertebrate and invertebrate abundance beneath burnt and unburnt fence posts was monitored for 13 months in unburnt forest and forest burnt by a wildfire. Key results Both vertebrate and invertebrate fauna made significantly less use of charred refuges. In most taxa, twice as many animals occurred under unburnt as under burnt artificial timber refuges, ant nests being the exception. Fauna made greater use of experimental refuges in burnt forest. Key conclusions Partially burnt fallen-timber refuges, where the log surface is left charred, are inferior habitat for fauna. Habitat quality in burnt forest may be enhanced by introducing fallen timber. Implications The study highlights an ecological consequence of fire for habitat quality, whether through wildfire or hazard-reduction burning, which should be considered in fire management.

Context
The Australian cotton industry has committed to (1) understanding the biodiversity value of remnant native vegetation on cotton farms, (2) funding independent, evidence-based assessments of the industry's sustainability and environmental performance, and (3) investing in research that reports against recognised sustainability indicators.

Aims
The present study reports the results of an industry-wide survey to benchmark bird diversity in native vegetation on cotton farms spanning a 1260-km north–south subcontinental gradient from Central Queensland (Qld) to Southern New South Wales (NSW).

Methods
Between September and November 2014, birds were sampled twice on separate days in 2-ha quadrats (20 min per census) in eight remnant vegetation types as well as in native revegetation at 197 sites on 60 cotton farms spread across the principal cotton-growing zones (Central Qld, Border Rivers, Macquarie and Southern NSW) in inland eastern Australia.


Key results
We recorded 185 bird species in remnant and planted native vegetation on cotton farms. Species richness of bird communities declined from north to south. Bird community composition was similar in the three southern zones, differing somewhat in the north. The most frequent species were large (>60 g), readily detected landbirds common in agricultural districts, but 26 of the 53 extant species of conservation concern in the study region were also recorded, including 16 species of declining woodland birds. Bird composition, abundance, richness and diversity differed among the nine native vegetation types, with maximal and minimal bird abundance and diversity metrics recorded in river red gum-dominated riparian vegetation and grassland respectively.


Conclusions
Each remnant vegetation community had a generally distinct bird assemblage, indicating that all vegetation types contribute to regional biodiversity in cotton-growing zones in inland eastern Australia. Appropriate on-farm management of all remnant and planted native vegetation will assist regional biodiversity conservation.


Implications
For the Australian cotton industry to meet its stated environmental responsibilities, growers should be encouraged to prioritise the conservation management of remnant, riparian and planted native vegetation on cotton farms and the monitoring of bird species as an indicator of regional biodiversity response.

Context
When measuring grazing impacts of vertebrates, the density of animals and time spent foraging are important. Traditionally, dung pellet counts are used to index macropod grazing density, and a direct relationship between herbivore density and foraging impact is assumed. However, rarely are pellet deposition rates measured or compared with camera-trap indices.

Aims
The aims were to pilot an efficient and reliable camera-trapping method for monitoring macropod grazing density and activity patterns, and to contrast pellet counts with macropod counts from camera trapping, for estimating macropod grazing density.

Methods
Camera traps were deployed on stratified plots in a fenced enclosure containing a captive macropod population and the experiment was repeated in the same season in the following year after population reduction. Camera-based macropod counts were compared with pellet counts and pellet deposition rates were estimated using both datasets. Macropod frequency was estimated, activity patterns developed, and the variability between resting and grazing plots and the two estimates of macropod density was investigated.

Key Results
Camera-trap grazing density indices initially correlated well with pellet count indices (r2=0.86), but were less reliable between years. Site stratification enabled a significant relationship to be identified between camera-trap counts and pellet counts in grazing plots. Camera-trap indices were consistent for estimating grazing density in both surveys but were not useful for estimating absolute abundance in this study.

Conclusions
Camera trapping was efficient and reliable for estimating macropod activity patterns. Although significant, the relationship between pellet count indices and macropod grazing density based on camera-trapping indices was not strong; this was due to variability in macropod pellet deposition rates over different years. Time-lapse camera imagery has potential for simultaneously assessing herbivore foraging activity budgets with grazing densities and vegetation change. Further work is required to refine the use of camera-trapping indices for estimation of absolute abundance.

Implications
Time-lapse camera trapping and site-stratified sampling allow concurrent assessment of grazing density and grazing behaviour at plot and landscape scale.