Description:
Vegetation can exert a strong influence on the distribution and activity of biotic communities across a broad range of spatial scales, especially in arid and semi-arid ecosystems. At fine spatial scales, patches created by individual plants can support different faunal and floral communities even at locations distant from the plant. These differences can have profound effects on a range of ecosystem processes, including seed dispersal, nutrient cycling and resource distribution. In semi-arid Australia, areas surrounding groves of western myall (Acacia papyrocarpa) trees are largely devoid of vegetation, being referred to as ‘halos’. Here, we investigate the soil-dwelling Collembola in groves of western myall trees, the surrounding halos and nearby chenopod shrubland. We also investigated whether the abundance of Collembola was influenced by soil depth (0–5 cm layer vs. 6–10 cm layer) in groves. We found that collembolan density was approximately nine times lower and taxonomic richness half that in a halo compared with the grove and chenopod vegetation. Furthermore, analyses at finer taxonomic levels indicate that vegetation patches differed in species composition, with some species restricted to or preferring particular patches. In the grove, we found a higher abundance of Collembola in the 0–5 cm soil layer compared with the 6–10 layer. Our results indicate vegetation patches strongly influence collembolan abundance and species composition in bare patches around western myall. As patches created by vegetation are a common feature of semi-arid and arid regions, we suspect that these effects are widespread although seldom reported. Furthermore, as Collembola are involved in the decomposition process, Acacia papyrocarpa patches will be influencing nutrient cycling through their effects on the soil biota. Our results also emphasize that comprehensive fauna survey and management of woodland ecosystems need to consider fine-scale processes.
Description:
This study suggested that long-term persistence of willow roots can provide a positive effect on aquatic communities until the new native vegetation cover establishes. Leaf type has no significant influence over taxa richness; however their availability and persistence in the system has a significant effect on macroinvertebrate abundance in these streams. A combination of Phragmites reeds with Leptospermum and CalUstemon shrubs in revegetation programs will ensure a persistent supply of leaf litter to macroinvertebrate communities in these streams thus should be retained until native canopy cover eg. Eucalyptus spp. is re-established.
Description:
This study suggested that long-term persistence of willow roots can provide a positive effect on aquatic communities until the new native vegetation cover establishes. Leaf type has no significant influence over taxa richness; however their availability and persistence in the system has a significant effect on macroinvertebrate abundance in these streams. A combination of Phragmites reeds with Leptospermum and CalUstemon shrubs in revegetation programs will ensure a persistent supply of leaf litter to macroinvertebrate communities in these streams thus should be retained until native canopy cover eg. Eucalyptus spp. is re-established.
Description:
To clarify species diversity of Tolypella (Characeae, Charophyceae) and the relationship between Tolypella and other genera in Characeae, sequence data from the nuclear ribosomal operon were assembled for 18 individuals of Tolypella. These represented nine named species and two potentially new species from Australia, as well as 13 other taxa of Characeae. Phylogenetic analyses were performed on ribosomal gene sequences (18S, 5.8S and 28S) for Characeae and on ribosomal gene and internal transcribed spacer (ITS) sequences (ribosomal genes þ ITS1 þ ITS2) for Tolypella. Analyses were also performed on the ribosomal gene and ITS sequences combined with plastid gene sequences (atpB, psbC and rbcL). Ribosomal gene sequences alone were conservative and their phylogenetic analyses resulted in topologies similar to a previously published plastid gene-based study but with less support and resolution. In contrast, ITS sequences showed greater variability and their addition resulted in greater resolution among some species relationships of Tolypella. The addition of plastid sequences also resulted in greater support and increased resolution in some lineages but not all.
Description:
Semi-arid rangelands have strong feedbacks between vegetation and abiotic factors (rainfall and soil), which manifest at the small patch/inter-patch scale. The effects of excluding grazing at the small patch scale have not been studied in these systems, despite fine-grained patch/inter-patch mosaics determining landscape-scale ecosystem function and productivity. We established small (1 m × 1 m) grazing exclosures and monitored change in herbaceous vegetation cover quarterly over 2 years, in grazed and ungrazed patches (high herbaceous vegetation cover) and inter-patches (low herbaceous vegetation cover), in woody encroachment and pasture sites in semi-arid eastern Australia. Prior to excluding grazing, herbaceous groundcover in pasture patches (63–67%) was significantly greater than in woody encroachment patches (15–16%) or inter-patches in both vegetation states (0–1%). The effect of grazing exclusion on herbaceous cover varied between patch type and vegetation state. In the absence of grazing, herbaceous cover was significantly greater in pasture patches than in woody encroachment patches at every monitoring time. Initial differences in herbaceous cover between woody encroachment patches and pasture patches was significantly less pronounced with continued grazing pressure, indicating that grazing pressure can negatively influence the positive effect of a lack of woody plants on herbaceous growth in pastures. Grazed pasture patches had significantly less herbaceous cover than ungrazed pasture patches at every monitoring time, whereas in woody encroachment, grazed patches had less herbaceous cover than ungrazed patches on only two occasions in the second year. Inter-patches in both vegetation states failed to respond to grazing exclusion in the 2-year study period. Herbaceous cover change in semi-arid rangelands is a function of grazing, rainfall and woody plant incidence. If grazing pressure in pasture patches is not carefully managed to maintain herbaceous cover, the positive effects of high rainfall and low woody plant abundance on herbaceous cover can rapidly diminish. Improving herbaceous groundcover overall will require an interventionist approach to overcome barriers to plant establishment in inter-patch areas such as the lack of resource retention.
Description:
The stomach flushing technique is a vital tool in bird dietary studies. The technique requires a tube to be inserted into the penguin's mouth and passed through the oesophagus to the stomach. General practice does not include cleaning of the tube between penguins. This report investigates if the stomach flushing tube can be a vehicle to transmit potential pathogens from a sick penguin to a healthy penguin, and if implementation of aseptic or disinfection practice is warranted in the stomach flushing technique. A total of 19 tubes from 19 penguins were examined for bacterial presence from May until August 2007. This paper presents new recommendations for stomach flushing procedures from a microbial perspective to ensure that birds subjected to this are not jeopardised by practices that may promote the transfer of potential pathogens from one penguin to another.
Description:
Technical challenges in using diatoms for paleolimnological work are the identification and enumeration of diatom valves. Variations exist in the minimum number of valves to identify, ranging from 100 to 700 valves of the dominant species. This task can be very time consuming, particularly when the diatom valves are not abundant. This research was conducted to determine the minimum number of valves to be identified in the diatom assemblages from Rawapening Lake, Central Java, Indonesia. Based on the 314 samples obtained from Rawapening Lake, the diatom efficiency rose above 0.85 upon the minimum count of 300 valves. The number of diatom species identified remained stable after the minimum of 300 valves. Therefore, the minimum number of diatom's valves identified to represent the assemblage for paleolimnological analysis was 300.
Description:
Technical challenges in using diatoms for paleolimnological work are the identification and enumeration of diatom valves. Variations exist in the minimum number of valves to identify, ranging from 100 to 700 valves of the dominant species. This task can be very time consuming, particularly when the diatom valves are not abundant. This research was conducted to determine the minimum number of valves to be identified in the diatom assemblages from Rawapening Lake, Central Java, Indonesia. Based on the 314 samples obtained from Rawapening Lake, the diatom efficiency rose above 0.85 upon the minimum count of 300 valves. The number of diatom species identified remained stable after the minimum of 300 valves. Therefore, the minimum number of diatom's valves identified to represent the assemblage for paleolimnological analysis was 300.
Description:
Exotic willows (Salix spp.) are widespread riparian tree species of rivers in temperate Australia and New Zealand. Despite being a Weed of National Significance, little is known about the novel habitats created by willows and the impact on aquatic biota of vegetation change following willow management programs. Reeds (Phragmites australis) and shrubs (Leptospermum spp. znaCallistemon spp.) are common taxa in the riparian zone of Victorian streams and are considered suitable for planting along channels in revegetation programs following willow removal. Categorisation of macroinvertebrates into 'trophic' groups allows better understanding of the processes of energy flow, material cycle and stream ecosystem function. Macroinvertebrate functional feeding groups associated with willow, Phragmites australis, Leptospermum/CaUistemon and bare bank habitats were examined in three central Victorian streams to gain insights to potential effects of willow removal on functional organisation of macroinvertebrates. There was a significant effect of habitat on macroinvertebrate functional feeding groups except collectors. Notable differences in functional feeding groups included a greater abundance ofpredators and grazers in Phragmites habitats and a greater abundance of snredders in willow habitats; however, these changes were variable during different seasons. It appears riparian vegetation change associated with willow management could bring about change of functional organisation of macroinvertebrates in these streams. This suggests that the vegetation changes can bring about changes in material cycle and energy flow within these streams.
Description:
Differences in the assemblages of terrestrial arthropod communities in burnt and adjacent unburnt areas of coastal heathland are reported. The burnt site experienced a wildfire 20 months prior to sampling. Collections of invertebrates from pitfall traps in winter indicated that there was no difference in total species richness or total numbers of individuals trapped between burnt and unburnt plots. However, at species level, 60 percent of the taxa showed a strong preference for either burnt areas or unburnt areas with only a few species trapped in around equal numbers in both areas. Twenty percent of species were only found on the unburnt plots. The implications of these results for fire management are discussed.
Description:
Understanding how vegetation composition varies with season and interannual climate variability is important for any ecological research that uses vegetation data derived from surveys for the basis of inference. Misunderstanding this variation can influence land management and planning decisions, leading to poor implementation of biodiversity offsetting mechanisms, for example. We monitored plots (400 m2) grazed by livestock paired with adjacent ungrazed plots in derived native pastures four times a year over 2.5 years on the North-West Slopes of New South Wales. Species density in plots varied greatly with season and interannual rainfall. Highest species density was recorded in spring, though species density in summer was not significantly lower, nor was a spring–summer peak in species density evident in the 2009 drought. Surveys in spring 2008 had the highest species density, and recorded only 60–72% of the total species recorded at each site over 2.5 years. Variation in the proportion of total site diversity represented in combinations of two or three surveys was large, though the best combinations comprised surveys from spring and summer in years of above-average rainfall, either from the same spring-summer, or from different years. Compositional differences among sites were much greater than within sites, showing that differences among sites related to broad environmental gradients were not overwhelmed by seasonal and interannual variability in site composition. When grazing was excluded, there was no evidence of competitive exclusion by the dominant grasses, and no directional shift in composition. The implications of these findings for ecological research depend on the question being addressed: if capturing a large proportion of site diversity is important, then surveys must be carefully timed, or repeat surveys must be conducted. Single surveys did not effectively capture site diversity for use in biodiversity offsetting, and the timing of repeat surveys was critical.
Description:
Conserving biodiversity is of utmost importance on a global scale. Species conservation, however, is a challenging task, which is often compounded by a lack of knowledge of target species. New advances in information technology and molecular techniques, however, are enabling conservation biologists to obtain large amounts of data quickly, which will certainly aid in assigning conservation priorities. This article reviews the use of genetics in conservation biology and highlights, using the Powerful Owl Ninox strenua as an example, how DNA can be a valuable source of data