Aspects of the population ecology of Galvanised Burr (Sclerolaena birchii).

1981 ◽  
Vol 3 (2) ◽  
pp. 142 ◽  
Author(s):  
BA Auld
Keyword(s):  
Population Ecology ◽  
Appreciable Effect ◽  
Effective Rainfall ◽  
Eastern Australia ◽  
Tap Root ◽  
Species Population ◽  
A Site ◽  
Vertical Height ◽  
Permanent Quadrats ◽  
Semi Arid

The population ecology of galvanised burr, Sclerolaena birchii (syn. Bassia birchii), at a site in semi-arid N.S.W. is described. Data were obtained from permanent quadrats, fenced and unfenced, with marked plants, using a quadrat with vertical height adjustment for locating individuals. Deliberately buried woody fruiting perianths ('burrs') were monitored for wall breakdown, which permits seed germination. There was no appreciable effect of grazing on the species population dynamics. Once established, few plants survived for more than two years. Populations exhibited Deevey type 111 survival curves which could be related to tap root growth and rainfall. Maximum breakdown of fruiting perianths occurred in 1 to 4 years. Provided rainfall was sufficient for germination and establishment, flushes of galvanised burr populations might be expected at intervals of 5 to 7 years. Because of the irregularity of effective rainfall in semi-arid eastern Australia 'burr years' occur less frequently. An explanation for their occurrence after droughts is presented.

Effects of ants on sandy soils in semi-arid eastern Australia .2. Relocation of nest entrances and consequences for bioturbation

Soil Research ◽  
1994 ◽  
Vol 32 (2) ◽  
pp. 323 ◽  
Author(s):  
DJ Eldridge ◽  
J Pickard
Keyword(s):  
Environmental Variables ◽  
Sandy Soils ◽  
Water Erosion ◽  
Nest Entrance ◽  
Micro Scale ◽  
Eastern Australia ◽  
Permanent Quadrats ◽  
Semi Arid ◽  
Over Time ◽  
Subsequent Incorporation

The rate of bioturbation by funnel ants (Aphaenogaster barbigula) was studied on an aeolian soil in western N.S.W. Nest entrances were tagged and monitored on permanent quadrats between May 1991 and May 1993. Nest entrances remained active for approximately 9 months and, on average, changed their location twice per year. Annual bioturbation was 336 g m-2 yr-1 which was equivalent to the annual development of a layer 0.28 mm thick. Bioturbation activity was poorly correlated with environmental variables. We estimate that 92% of the total volume of the soil would be removed from the profile during the construction of nest entrances within 100 years, and 100% within 200 years. This provides strong evidence that development of these soils is principally biogenic and may explain why there is little or no horizon development, or changes in particle size distribution with depth. Bioturbation is substantially greater than estimates of water erosion in these soils, suggesting that over time soil brought to the surface will lead to the development of a new layer. This deposition and subsequent incorporation of organic matter in the surface soils around the nest entrance may have consequences for enhanced nutrient development on a micro scale.

scholarly journals Fire and Its Interactions With Other Drivers Shape a Distinctive, Semi-Arid ‘Mallee’ Ecosystem

2021 ◽  
Vol 9 ◽  
Author(s):  
Michael F. Clarke ◽  
Luke T. Kelly ◽  
Sarah C. Avitabile ◽  
Joe Benshemesh ◽  
Kate E. Callister ◽  
...  
Keyword(s):  
Regional Scale ◽  
Fire Regimes ◽  
Field Studies ◽  
Arid Ecosystems ◽  
Coarse Grained ◽  
Pest Species ◽  
Age Classes ◽  
Eastern Australia ◽  
Animal Communities ◽  
Semi Arid

Fire shapes ecosystems globally, including semi-arid ecosystems. In Australia, semi-arid ‘mallee’ ecosystems occur primarily across the southern part of the continent, forming an interface between the arid interior and temperate south. Mallee vegetation is characterized by short, multi-stemmed eucalypts that grow from a basal lignotuber. Fire shapes the structure and functioning of mallee ecosystems. Using the Murray Mallee region in south-eastern Australia as a case study, we examine the characteristics and role of fire, the consequences for biota, and the interaction of fire with other drivers. Wildfires in mallee ecosystems typically are large (1000s ha), burn with high severity, commonly cause top-kill of eucalypts, and create coarse-grained mosaics at a regional scale. Wildfires can occur in late spring and summer in both dry and wet years. Recovery of plant and animal communities is predictable and slow, with regeneration of eucalypts and many habitat components extending over decades. Time since the last fire strongly influences the distribution and abundance of many species and the structure of plant and animal communities. Animal species display a discrete set of generalized responses to time since fire. Systematic field studies and modeling are beginning to reveal how spatial variation in fire regimes (‘pyrodiversity’) at different scales shapes biodiversity. Pyrodiversity includes variation in the extent of post-fire habitats, the diversity of post-fire age-classes and their configuration. At regional scales, a desirable mix of fire histories for biodiversity conservation includes a combination of early, mid and late post-fire age-classes, weighted toward later seral stages that provide critical habitat for threatened species. Biodiversity is also influenced by interactions between fire and other drivers, including land clearing, rainfall, herbivory and predation. Extensive clearing for agriculture has altered the nature and impact of fire, and facilitated invasion by pest species that modify fuels, fire regimes and post-fire recovery. Given the natural and anthropogenic drivers of fire and the consequences of their interactions, we highlight opportunities for conserving mallee ecosystems. These include learning from and fostering Indigenous knowledge of fire, implementing actions that consider synergies between fire and other processes, and strategic monitoring of fire, biodiversity and other drivers to guide place-based, adaptive management under climate change.

Accumulation of soil carbon under zero tillage cropping and perennial vegetation on the Liverpool Plains, eastern Australia

Soil Research ◽  
2009 ◽  
Vol 47 (3) ◽  
pp. 273 ◽  
Author(s):  
R. R. Young ◽  
B. Wilson ◽  
S. Harden ◽  
A. Bernardi
Keyword(s):  
Field Experiment ◽  
Soil Carbon ◽  
Cropping Systems ◽  
Annual Rainfall ◽  
Continuous Cropping ◽  
Zero Tillage ◽  
Accumulation Rates ◽  
Eastern Australia ◽  
Perennial Vegetation ◽  
Semi Arid

Australian agriculture contributes an estimated 16% of all national greenhouse gas emissions, and considerable attention is now focused on management approaches that reduce net emissions. One area of potential is the modification of cropping practices to increase soil carbon storage. Here, we report short–medium term changes in soil carbon under zero tillage cropping systems and perennial vegetation, both in a replicated field experiment and on nearby farmers’ paddocks, on carbon-depleted Black Vertosols in the upper Liverpool Plains catchment. Soil organic carbon stocks (CS) remained unchanged under both zero tillage long fallow wheat–sorghum rotations and zero tillage continuous winter cereal in a replicated field experiment from 1994 to 2000. There was some evidence of accumulation of CS under intensive (>1 crop/year) zero tillage response cropping. There was significant accumulation of CS (~0.35 Mg/ha.year) under 3 types of perennial pasture, despite removal of aerial biomass with each harvest. Significant accumulation was detected in the 0–0.1, 0.1–0.2, and 0.2–0.4 m depth increments under lucerne and the top 2 increments under mixed pastures of lucerne and phalaris and of C3 and C4 perennial grasses. Average annual rainfall for the period of observations was 772 mm, greater than the 40-year average of 680 mm. A comparison of major attributes of cropping systems and perennial pastures showed no association between aerial biomass production and accumulation rates of CS but a positive correlation between the residence times of established plants and accumulation rates of CS. CS also remained unchanged (1998/2000–07) under zero tillage cropping on nearby farms, irrespective of paddock history before 1998/2000 (zero tillage cropping, traditional cropping, or ~10 years of sown perennial pasture). These results are consistent with previous work in Queensland and central western New South Wales suggesting that the climate (warm, semi-arid temperate, semi-arid subtropical) of much of the inland cropping country in eastern Australia is not conducive to accumulation of soil carbon under continuous cropping, although they do suggest that CS may accumulate under several years of healthy perennial pastures in rotation with zero tillage cropping.

scholarly journals Why and how might genetic and phylogenetic diversity be reflected in the identification of key biodiversity areas?

2015 ◽  
Vol 370 (1662) ◽  
pp. 20140019 ◽  
Author(s):  
T. M. Brooks ◽  
A. Cuttelod ◽  
D. P. Faith ◽  
J. Garcia-Moreno ◽  
P. Langhammer ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Threatened Species ◽  
Phylogenetic Diversity ◽  
Species Population ◽  
Threatened Taxa ◽  
Conservation Actions ◽  
Ecosystem Diversity ◽  
Species Specific ◽  
A Site ◽  
Specific Conservation

‘Key biodiversity areas' are defined as sites contributing significantly to the global persistence of biodiversity. The identification of these sites builds from existing approaches based on measures of species and ecosystem diversity and process. Here, we therefore build from the work of Sgró et al. (2011 Evol. Appl. 4 , 326–337. ( doi:10.1111/j.1752-4571.2010.00157.x )) to extend a framework for how components of genetic diversity might be considered in the identification of key biodiversity areas. We make three recommendations to inform the ongoing process of consolidating a key biodiversity areas standard: (i) thresholds for the threatened species criterion currently consider a site's share of a threatened species' population; expand these to include the proportion of the species' genetic diversity unique to a site; (ii) expand criterion for ‘threatened species' to consider ‘threatened taxa’ and (iii) expand the centre of endemism criterion to identify as key biodiversity areas those sites holding a threshold proportion of the compositional or phylogenetic diversity of species (within a taxonomic group) whose restricted ranges collectively define a centre of endemism. We also recommend consideration of occurrence of EDGE species (i.e. threatened phylogenetic diversity) in key biodiversity areas to prioritize species-specific conservation actions among sites.

An extension to the known range of the eastern grey kangaroo Macropus giganteus on Cape York Peninsula.

2005 ◽  
Vol 27 (2) ◽  
pp. 225 ◽  
Author(s):  
EG Ritchie
Keyword(s):  
Arid Regions ◽  
Grey Kangaroo ◽  
Eastern Australia ◽  
Northern Cape ◽  
Cape York ◽  
Open Forests ◽  
Semi Arid

THE eastern grey kangaroo (Macropus giganteus) is one of Australia?s widest-ranging large macropodids, occurring in open forests, woodlands, subalpine woodland, farmland, and semi-arid regions throughout most of eastern Australia (Menkhorst and Knight 2001). However current general accounts (e.g., Poole 1995, Menkhorst and Knight 2001) regard M. giganteus as being absent from the northern Cape York Peninsula.

The Rabbit in Subalpine South-eastern Australia. I. Population Structure and Productivity

1974 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
DJ Dunsmore
Keyword(s):  
Population Structure ◽  
National Park ◽  
Initial Level ◽  
Adult Survival ◽  
South Eastern ◽  
Breeding Group ◽  
Eastern Australia ◽  
Domestic Livestock ◽  
A Site ◽  
Better Than

An unconfined, almost completely tagged rabbit population on a site of about 100 ha was studied by observation and trapping for 5 years. The commencement of the study coincided approximately with the incorporation of the area into the Kosciusko National Park, the elimination of grazing by domestic livestock, and the cessation of the previously almost annual burning of the area. During the 5-yr study the fecundity of the rabbits declined to little more than half the initial level. This was not a result of the concurrently increasing age of the population, which was shown to be quite unrelated. It was also shown that the 1yr old rabbits were less fecund than the older rabbits, whose fecundity remained constant. Although it appeared subjectively to be so, the area was not uniformly suitable for the survival of rabbits. In one of its four subdivisions adult survival was much better than in the others; and in one of the others it was much the worst. During the study there was considerable immigration to the area, presumably balanced by migration. Females tended to remain where they were born and in no case changed from one breeding group to another. Males were considerably less sedentary than the females.

Wind Dispersal of the Vagant Lichen Chondropsis semiviridis in Semi-arid Eastern Australia

1999 ◽  
Vol 47 (2) ◽  
pp. 157 ◽  
Author(s):  
D. J. Eldridge ◽  
J. F. Leys
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Wind Dispersal ◽  
Wind Speed Data ◽  
Litter Cover ◽  
Eastern Australia ◽  
Wind Velocities ◽  
Semi Arid

A field-based wind tunnel was used to assess threshold wind velocities required to initiate movement of the vagant lichen Chondropsis semiviridis (F.Muell. ex Nyl.) Nyl. in a semi-arid eastern Australian woodland. Threshold wind velocities were lowest on bare surfaces (21 km h-1) and highest on surfaces covered with the needle-like litter of Casuarina cristata Miq. trees (58 km h-1). Examination of wind speed data suggests that threshold wind velocities for movement on litter-covered surfaces occur about 1% of the time in summer. The extensive litter cover in the groves, and the tendency of C. semiviridis to firmly attach to this litter, probably explains the concentration of C. semiviridis in the groves and the low rates of migration and emigration during most years. It is hypothesised that migration of C. semiviridis between timbered groves would only occur during extreme droughts when pasture and litter cover are sparse.

Regeneration of Three Tree Species in Arid South-Eastern Australia

1985 ◽  
Vol 33 (6) ◽  
pp. 715 ◽  
Author(s):  
CJ Chesterfield ◽  
RF Parsons
Keyword(s):  
Nature Conservation ◽  
Tree Species ◽  
Arid Zone ◽  
Tree Seedlings ◽  
Seedling Regeneration ◽  
Mammalian Herbivores ◽  
Eastern Australia ◽  
Rabbit Grazing ◽  
A Site

Grazing effects by introduced mammals on tree seedlings in the arid zone have caused concern for the long-term future of some tree species. This was investigated by measuring stem girths of Casuarina cristata Miq., Heterodendrum oleifoliurn Desf. and Myoporum platycarpum R.Br. in arid-zone wood- lands. Episodic seedling regeneration of Myoporum is inferred following series of wet years in the 1950s and 1970s. Although young Myoporum plants appear unpalatable to stock, regeneration may be sup- pressed by rabbit-grazing in some areas. Almost no Heterodendrurn seedlings were found but suckering was common after burning and clearing. This species is highly palatable to grazing mammals and suckers may grow to safety above the browse line only where stock are absent. Evidence for recent Casuarina seedling regeneration was limited to one cohort, on a site that had been flooded. While suckers can be found locally where surface roots become exposed, suckering appears insufficient to perpetuate many Casuarina stands. Mammal-grazing seems important in strongly limiting regeneration. While Casuarina and Heterodendrum stand densities decline due to natural senescence and occasional fire, the only species regenerating into gaps is Myoporum. There is concern for the future of Casuarina and Heterodendrum, given their widespread failure to regenerate despite the wettest 3 years ever recorded, in 1973-75. On pastoral land, at least 10 years without stock-grazing might be needed for successful regeneration of Heterodendrurn. In reserves, some nature conservation programs for woodlands might require virtual eradication of all exotic mammalian herbivores, including goats.

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