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.

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.

Effect of ants on sandy soils in semi-arid eastern Australia - Local distribution of nest entrances and their effect on infiltration of water

Soil Research ◽  
1993 ◽  
Vol 31 (4) ◽  
pp. 509 ◽  
Author(s):  
DJ Eldridge
Keyword(s):  
Nature Reserve ◽  
Sandy Soils ◽  
Water Infiltration ◽  
Arid Environments ◽  
Local Distribution ◽  
Small Areas ◽  
Eastern Australia ◽  
Callitris Glaucophylla ◽  
State Water ◽  
Semi Arid

The influence of the funnel ant (Aphaenogaster barbigula) on water infiltration was studied on an aeolian soil in a semi-arid Callitris glaucophylla woodland in eastern Australia. At the study site at Yathong Nature Reserve, densities of up to 37 nest entrances m-2 were recorded in some areas, equivalent to a density of 88 000 entrances ha-1 over small areas or 0.9% of the surface area of the landscape. Seventy-two per cent of the entrances were actively being used by the ants. Steady-state water infiltration on soils with entrances averaged 23.3 mm min-1 which was about four times that on entrance-free soils. As the diameter of the nest entrance increased, water penetrated deeper into the soil. The results provide further evidence that ants have a marked influence on redistribution of water in semi-arid environments.

scholarly journals Kinetically driven successive sodic and potassic alteration of feldspar

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gan Duan ◽  
Rahul Ram ◽  
Yanlu Xing ◽  
Barbara Etschmann ◽  
Joël Brugger
Keyword(s):  
Hydrothermal Fluid ◽  
Large Scale ◽  
Ore Deposits ◽  
Potassic Alteration ◽  
Positive Feedbacks ◽  
Micro Scale ◽  
Equilibrium Reaction ◽  
Earth's Crust ◽  
Mineral Transformations ◽  
Over Time

AbstractThe dynamic evolutions of fluid-mineral systems driving large-scale geochemical transformations in the Earth’s crust remain poorly understood. We observed experimentally that successive sodic and potassic alterations of feldspar can occur via a single self-evolved, originally Na-only, hydrothermal fluid. At 600 °C, 2 kbar, sanidine ((K,Na)AlSi3O8) reacted rapidly with a NaCl fluid to form albite (NaAlSi3O8); over time, some of this albite was replaced by K-feldspar (KAlSi3O8), in contrast to predictions from equilibrium reaction modelling. Fluorine accelerated the process, resulting in near-complete back-replacement of albite within 1 day. These findings reveal that potassic alteration can be triggered by Na-rich fluids, indicating that pervasive sequential sodic and potassic alterations associated with mineralization in some of the world’s largest ore deposits may not necessarily reflect externally-driven changes in fluid alkali contents. Here, we show that these reactions are promoted at the micro-scale by a self-evolving, kinetically-driven process; such positive feedbacks between equilibrium and kinetic factors may be essential in driving pervasive mineral transformations.

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.

Genotype Effects in Millet/Cowpea Intercropping in the Semi-arid Tropics of Niger

1990 ◽  
Vol 26 (4) ◽  
pp. 387-396 ◽  
Author(s):  
K. C. Reddy ◽  
J. van der Ploeg ◽  
I. Maga
Keyword(s):  
Pearl Millet ◽  
Crop Yields ◽  
Sandy Soils ◽  
Sole Crop ◽  
Early Maturing ◽  
Semi Arid ◽  
Genotype Effects

SUMMARYThree pearl millet and three cowpea genotypes were examined in intercropping systems on deep sandy soils in Niger between 1984 and 1987. The intercropped pearl millet genotypes usually produced at least 80% of their sole crop yields when the cowpea was planted two or more weeks after the pearl millet. The early maturing and spreading cowpea genotype contributed most to LER. All cowpea genotypes yielded more when planted in association with dwarf rather than the traditional tall pearl millet genotypes because they received more light.

Evaluation of Water Erosion Risk in Tunisian Semi Arid Area

2017 ◽  
pp. 215-249 ◽  
Author(s):  
Olfa Hajji ◽  
Sahar Abidi ◽  
Taoufik Hermassi ◽  
Ikram Mekni
Keyword(s):  
Water Erosion ◽  
Arid Area ◽  
Erosion Risk ◽  
Semi Arid

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.

Sign in / Sign up

Export Citation Format

Share Document