Sites In South-western Australia Research Articles

The effect of concentrated smoke products on the restoration of highly disturbed mineral sands in southeast Victoria

Summary Recent studies have recognized the potential of broad‐scale surface application of smoke compounds for enhancing germination from the soil seed‐bank in fire‐prone vegetation communities. Results suggest that smoke technology may play, in the future, a significant role in the restoration and management of areas supporting indigenous vegetation. An important step in the development of smoke‐based restoration tools is the conduct of in situ field trials in a range of geographical locations and environmental conditions. However, most of the published work on the effectiveness of smoke products in promoting seedbank germination has been conducted at sites in southwestern Australia. The present study examines the effect of commercially available smoke‐water products on the regeneration of a highly disturbed former mine‐site at the Royal Botanic Gardens Cranbourne, in southeastern Victoria. Various combinations of concentrated smoke products and topsoil harvested from a nearby heathy woodland community were applied to exposed, uniform mineral sands to test their effect on seedling density and species richness of regrowth. The trials showed that after 12 months a number of common, herbaceous species including Austrodanthonia setacea, Opercularia varia and Platysace heterophylla were recorded in significantly higher numbers in areas treated with a commercial smoke‐water. However, there was no overall improvement in the density of seedlings or the richness of species as a result of the application of the smoke products. Similarly, total seedling density and species richness were not affected by the addition of topsoil, either alone or in combination with smoke products.

Thermal biology of large snakes in cool climates: a radio-telemetric study of carpet pythons (Morelia spilota imbricata) in south-western Australia

Radio-telemetric monitoring of 70 free-ranging carpet pythons (Morelia spilota imbricata) at two sites in south-western Australia provided extensive data on the body temperatures exhibited by these animals. The snake's thermal regimes were affected by season, time of day, location, microhabitat, size and sex, behaviour, and reproductive state. Over most of the year pythons exhibited relatively smooth unimodal diel curves of heating and cooling, attaining maximal temperatures around 30°C. The (small) male snakes heated and cooled more rapidly than did the (larger) females. Climatic differences between our two study sites generated substantial shifts in mean body temperatures and thus, in the diel timing of ambush foraging behaviour. Females wrapped tightly around their eggs after oviposition and brooded them throughout the ensuing 8-week incubation period. Throughout this time, females were facultatively endothermic, maintaining high constant temperatures through shivering thermogenesis. Females nesting in sites with relatively poor thermal buffering (under rootballs of fallen trees rather than rock crevices) supplemented endogenous heat production with occasional basking, and hence overall maintained lower and more variable incubation temperatures than did females with “better” nest sites.

Eucalyptus globulus harvest residue management effects on soil carbon and microbial biomass at 1 and 5 years after plantation establishment

Residues from harvest of eucalypt plantations represent a significant proportion of site organic matter and nutrients, and their management may influence longer term plantation productivity through changes in soil organic matter and nutrient supply. Experiments at two sites in south-western Australia were established to investigate the effects of harvest residue management on soil fertility and plantation productivity. The sites were a relatively fertile red earth, and a poorer-fertility grey sand. Harvest residue treatments were burning, complete removal of the above-ground material, retention and uniform distribution on site, and double the normal quantity of residues retained and distributed on site. Soil microbial biomass, an indicator of longer term (potentially several rotations) impacts of management on soil organic matter, was measured 1 and 5 years after planting. Retention of residues had minimal influence on total soil C and N, or C oxidized by 333 mM permanganate, but it significantly increased surface soil (0–5 cm) microbial biomass carbon (MBC) and nitrogen (MBN), as well as increasing the MBC and MBN quotients (ie. MBC and MBN as a proportion of the total soil C and N). Effects of residue management on MBC and MBN were generally highly significant 1 year after establishment, but differences between treatments had decreased after 5 years. Residue retention significantly increased MBC at both sites down to 20 cm depth, and significantly increased MBN at the red earth site at 1 year after establishment, but effects at 5 years were only evident in the surface (0–5 cm) soil. At 1 year, MBN in the surface (0–5 cm) soil was more responsive to residue retention than MBC, as the MBN quotient increased more than 2-fold at the red earth site, compared with only a 30% increase in MBC quotient. Higher MBC and MBN levels are due to greater availability of substrate derived from residues early in the rotation. The effect of residue management on microbial biomass was reduced at 5 years, and confined to the surface soil (0–5 cm), suggesting that availability of the organic material from the residues had declined. The decline was mainly due to utilization by the microbial biomass (respiration) or conversion to less labile forms.

Change in soil carbon after land clearing or afforestation in highly weathered lateritic and sandy soils of south-western Australia

Soil organic carbon (SOC) is a significant component of the worlds terrestrial carbon stocks, and changes in land-use have potential to change pools of soil C. Land-use change is occurring over large areas of the world, so soil has potential to be a large source or sink for atmospheric C. Changes in amounts of soil C (0–1 m) were examined after clearing of native vegetation for pasture (20–71 years prior to study), and after establishment of Eucalyptus globulus plantations on ex-pasture sites (7–10 years prior to study). A suite of 10 sites in south western Australia were used in a three-way comparison between native vegetation, pasture and plantation. Soil types across the 10 sites included Acrisols, Arenosols, and a Ferrosol. Soil C was measured in the fine earth (<2 mm), the 2–5 mm soil fraction, in charcoal and roots retained on a 5 mm screen, and in surface litter. Differences in soil bulk density between land-uses were accounted for by calculating depths for equivalent weights of soil. Despite large increases in soil fertility with conversion to pasture, amounts of soil C changed little. The amount of C in the 5–20 cm increment was significantly greater under pasture than native vegetation (mean of 8.4 Mg ha −1, <5 mm), but in surface soil (0–5 cm) and <20 cm, there were no significant differences in soil C content between land-uses. Less C in soil at 5–20 cm under native vegetation was offset by significantly more C in coarse roots (average of 5 Mg ha −1 higher to 1 m depth), surface soil (2–5 mm fraction, 2 Mg ha −1), and in standing pools of surface litter (9.8 Mg ha −1). Amounts of soil C under plantation were not significantly different from pasture 7–10 years after plantation establishment. However, plantation soils had an average of 3.1 Mg ha −1 more C in coarse roots than pasture, and significant quantities of C in surface litter (average of 7.9 Mg ha −1). Overall, soil C content in the sites of this study was relatively stable and the effect of land-use change was limited.

Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation

The influence of land-use management on Walkley-Black soil carbon (C) concentration, 3 concentrations of permanganate oxidisable C (33, 167, and 333 mm), microbial biomass, and soil respiration in a laboratory incubation was tested in surface soil from 10 sites in south-western Australia. The sites ranged in total C concentration from 1.9 to 8.3%, and represented a broad climatic and soil-type distribution across south-western Australia. At each of the sites, 0-10 cm soil was collected from plots in pasture (20-71 years old), Eucalyptus globulus plantation (7-10 years old, established on ex-pasture), and native vegetation. Soil profiles and position in the landscape for each of the land-use types were matched as closely as possible at each site to minimise influences other than land use. Total C was highly correlated with clay content. Land use caused no significant change in the relationship between total C and soil texture, and land use had little effect on total C concentration. Permanganate-oxidisable C was highly correlated with Walkley-Black organic C (R2�&amp;gt;�0.90) for all 3 concentrations that were investigated. Only the most dilute concentration of permanganate-oxidisable C (33 mm) was sensitive enough to detect small changes in soil organic matter with land use (P = 0.045). Microbial biomass and respiration at 25 kPa matric potential moisture content and 35°C temperature were used as biological indicators of soil organic matter lability. Cumulative respired C was more sensitive to land use than Walkley-Black organic C, with lower respiration in native soils compared with managed soils with low C concentrations, but higher than the managed soils at sites with high C concentrations. Microbial biomass was not significantly affected by land use. Microbial biomass and cumulative respired C were strongly influenced by soil texture, with the microbial quotient (proportion of microbial biomass in total carbon) and the proportion of total C respired significantly lower in soils with higher silt and clay contents. Land use had no significant effect on these relationships. Overall, land use caused only minor differences in the biological and chemical indicators of organic matter quality across a broad range of sites in south-western Australia.

Genetic subdivision of Roe’s abalone, Haliotis roei Grey (Mollusca : Gastropoda), in south-western Australia

Starch-gel electrophoresis was used to investigate population structure of the commercially and recreationally exploited abalone, Haliotis roei. The standardized variance in allelic frequencies among 10 sites in south-western Australia indicated relatively high levels of gene flow across the 3000 km range sampled (mean FST 0.009). Sites showed no striking geographic trends in allelic frequencies or apparent clustering, on the basis of multidimensional scaling of GST as a measure of genetic dissimilarity. A population structure of isolation-by-distance was evident when pairwise measures of GST were related to geographic distance (r = 0.45, P &lt;0.001). This relationship was evident beneath relatively high levels of variability among pairwise comparisons of GST for sites separated by small distances. The area of complete genetic mixing, or neighbourhood size, was estimated to be less than the distance between the two nearest sites, or 13 km. The apparent contradiction between relatively high levels of gene flow across the species’ distribution, as indicated by a low average FST, and substantial heterogeneity between sites separated by 10s of kilometres, is discussed in the context of the species’ biology, and management of the fishery.

Interactions between trees and groundwaters in recharge and discharge areas – A survey of Western Australian sites

In Australia revegetation of both groundwater recharge and discharge areas is seen as a fundamental element of dryland salinity management. Millions of trees are planted each year with the intention of controlling rising water tables induced by the clearing and subsequent replacement of native, deep-rooted vegetation with lower water use agriculture systems. These trees are planted in areas with either considerable depths to the water table (recharge areas) or in areas with shallow water tables and high soil salinity levels (discharge areas). To assess how trees established in these areas have altered groundwater conditions, observations from almost 80 sites in south-western Australia have been analysed. Statistical analyses suggest that planting trees in groundwater recharge areas will only lead to significant reductions in water levels if considerable areas of the catchment are planted. In discharge areas, the probability of achieving reduced water levels was lower and the magnitude of the response smaller. Additionally, in discharge areas, the maximum reduction of water tables from revegetation was about 2.5 m and the effect greatest where groundwater salinity was relatively low (<5000 mg l −1). Best results from revegetation occurred in local-scaled aquifers. Evidence presented in five case studies suggests that if the hydrogeologic conditions are well defined, tree plantations maybe a useful tool for localised salinity management. However, at all but three of the 80 sites reviewed, trees had little or no effect on the water tables more than 10–30 m from the planted area. The exceptions were the Merredin site, where preliminary data suggest that water tables appear to have been lowered by almost 1 m, 3 km from a large plantation and at the Narrikup and East Belka sites, where the water table was influenced 75 m upslope (Narrikup) and downslope (East Belka) from the planted area. If the objective of the land managers is to prevent the spread of salinity and reclaim existing areas, then only the adoption of broadacre recharge management systems can be effective in the longer term. Unless specified hydrologic conditions exist, our data suggest that only extensive plantings, perhaps influencing as much as 70–80% of the catchment, will lead to significant reductions in water tables and salinity control.

Genotype-environment interaction for seed yield and ODAP concentration of Lathyrus sativus L. and L. cicera L. in Mediterranean-type environments

Summary In 1994, 407 L. sativus and 96 L. cicera lines were evaluated for phenology, seed yield and seed ODAP (a neurotoxin) concentration in the Mediterranean-type climate of south-western Australia. A selected number of lines from this study were grown at three sites in south-western Australia in 1995 and 1996, to examine genotype-environment interactions on seed yield and ODAP concentration in the seed of the two Lathyrus spp. Principal components analysis showed that L. sativus lines grown in 1995 and 1996 could be divided into two geographical origins: Indian sub-continent and Mediterranean/European. Those lines of Mediterranean/European origin were consistently higher yielding (both in 1994 and 1995/96), with much larger seeds and later phenology. In L. cicera seed yield was closely associated with greater mean seed weight and to a lesser extent with early phenology. The genotype-environment study indicated that higher yielding lines of both species generally responded to favourable environments; in the case of L. sativus the Mediterranean/European lines and for L. cicera the larger seeded, earlier phenology lines. For both species, genotype was the most important determinant of ODAP concentration and environment had less influence. Genotype-environment interactions had no effect on seed ODAP concentrations. In terms of seed yield, both species showed substantial potential in the environments tested. Further improvements in adaptation, seed yield and reduction in ODAP are possible in both species. Abbreviations: ODAP: 3-(-N-oxalyl)-L-2,3-diamino propionic acid

Distribution of Aphids (Hemiptera: Aphididae) in Potato Growing Areas of Southwestern Australia

Sticky traps, water traps and leaf samples were used to monitor aphid populations at 32 sites in southwestern Australia between October and May for four seasons between 1988–92. Twenty‐seven sites were located in potato, Solanum tuberosum L., crops, with five others located in mixed vegetable crops or pastures. Sites were located in an area of approximately 90,000 km2, and encompassed most of the potato growing areas of the region. Thirty‐four species of aphids were detected. Potato‐colonising aphids found were Myzus persicae, Aulacorthum solani, Macrosiphum euphorbiae and Aphis craccivora. M. persicae was the most widespread, and its seasonal distribution in southwestern Australia is presented. Fewer M. persicae were recorded and it arrived later in the season for 2 of 3 years at southern sites than northern sites. At sites where both sticky traps and leaf sampling were used, leaf sampling often detected M. persicae before they were found on traps. Results suggest that potato crops grown on the southern coast will be least vulnerable to infection by aphid‐borne viruses.

Nitrogen Balance of Field Pea Crops in South Western Australia, Studied Using the 15N Natural Abundance Technique

The nitrogen economies of six contrasting field pea (Pisum sativum L.) genotypes were examined at three widely separated sites in south Western Australia, using the 15N natural abundance technique to asssess proportional dependence on fixed N, harvests at peak biomass to assess total N yields and harvests at crop maturity to examine partitioning of N between seed and non harvested crop residues. The budgets for one site (Wongan Hills) included N of nodulated roots which on average comprised 12% of total plant N at peak crop biomass and 25% of recoverable plant N after harvest of seed. At this site maximum potential (residual) benefits to a following crop (peak total plant biomass N - N uptake from soil and N taken off as harvested seed) varied between genotypes from 8 to 41 g N ha-1 (mean 26; n = 6). Data for the other two sites, based solely on N budgets of above-ground parts, provided evidence of substantial site- and genotype-specific differences in N balance in terms of shoot residues (i.e. + 7 to - 24 kg N ha-1 (mean - 5) at Avondale, + 40 to - 29 (mean + 3) at Mt Barker). The results collectively indicated a general relationship between peak biomass N of a crop and its potential or otherwise to effect a net input of residue N to the ecosystem. There were, however, considerable variations between genotypes and sites due to differences in proportional dependence on fixation (range across all sites and genotypes 60-91%) and crop harvest indices for N (corresponding range 53-90%). Correlation plots were constructed from the data for N2 fixed against crop dry matter yield and residual nitrogen benefit against nitrogen harvest index. Results are discussed in relation to values for N balance of field pea and other grain legumes obtained elsewhere by other investigators.

A field study of Pseudocheirus occidentalis (Marsupialia : Petauridae) II. Population studies

Field studies of the rare and endangered western ringtail possum (Pseudocheirus occidentalis) were undertaken at five main sites in south-western Australia. Population studies employing capture-markrelease and telemetry methods were concentrated at Abba River and Locke Estate, near Busselton, and supplementary telemetry records were obtained for three females at Yendicup, Perup, near Manjimup. The location of dreys and sightings were mapped at Geographe Bay (near Busselton) and Emu Point (Albany). Mature adults of both sexes weighed about 1000 g and attained maturity at 830-900 g. Young were estimated to spend about 104 days in the pouch and emerge at 130-150 g. Lactation ceased when young weighed 550-650 g. Most births were of single young, but at Locke 16.7% of females with pouch young carried twins. In the Busselton area some births occurred in all months, but there were few between December and March. Most births occurred during April-July, but a secondary peak occurred during September-November, especially at Locke. At Locke 69% of animals were females and this ratio was similar in all age classes, but at Abba the sex ratio was parity. At Locke hollows were rare and animals usually rested in dreys; at Abba hollows in Eucalyptus gomphocephala were the usual rest sites and dreys were rare, occurred only near the watercourse and were used only by males; at Yendicup no dreys were observed and hollows in eucalypts were the usual rest sites. Animals used 2-7 rest sites each. Home ranges of females at Yendicup averaged about 2.5 ha; in the Busselton area home ranges averaged less than 1 ha. Less than 1% of both day and night sightings were of animals at ground level. Plots of the location of dreys and sightings at three sites showed that possums were not evenly dispersed, and at two sites there were areas of apparently suitable habitat that were rarely used. Density was estimated for four sites: Abba River 3.7-4.3 ha-1, Locke Estate 2.4-4.5 ha-1, Geographe Bay 0.3-0.6 ha-1 and Emu Point 0.1-0.4 ha-1. Evidence of predation by foxes was found at Abba, Locke and Geographe Bay. Microscopic inspection of faecal pellets showed that, where Agonis flexuosa grew, its leaves accounted for 79-100% of diet. Small amounts of several other plants were also taken. At Perup A. flexuosa was absent and the diet consisted predominantly of leaves of the two common eucalypts (Eucalyptus calophylla and E. marginata).

Mössbauer Spectra of Soil Kaolins from South-Western Australia

AbstractSix well-characterized soil kaolins from widely separated sites in south-western Australia and four reference kaolins were studied by 57Fe Mössbauer spectroscopy at room temperature after removal of non-structurally-bound iron with dithionite-citrate-bicarbonate solution. The soil kaolins and one of the reference kaolins were also studied at temperatures near 16 K. The soil kaolins were remarkably similar in crystal size, crystallinity, dehydroxylation temperature, cation exchange capacity, surface area and iron content. Müssbauer spectra of the soil kaolins at room temperature were also essentially identical consisting of a quadrupole-split doublet superimposed on a broad component which indicated that all of the iron was present as Fe(III) and that slow paramagnetic relaxation effects were present. Mean values for the chemical isomer shift and quadrupole splitting of the doublet for the soil kaolins were 0.33 and 0.55 mm/s respectively which indicates that the iron is in the octahedral sites of the kaolin lattice. The spectra of the soil kaolin samples at temperatures near 16 K showed a further slowing down of the paramagnetic relaxation and confirmed that no discrete iron oxide minerals were present.Mössbauer spectra of the four reference kaolins at room temperature showed a doublet component similar to those for the soil kaolins. Three of them showed evidence for other spectral components including, in two cases, a component due to the presence of Fe(II).

The European Rabbit in South- Western Australia II. Reproduction

'The reproduction of the European rabbit, Oryctolagus cuniculus (L.), at two intensive study sites in south-western Australia is compared with reproductive data from rabbits taken throughout the coastal and inland districts of the south-west region. South-western Australia has hot, arid summers and cool wet winters. Rabbit breeding in the region is characteristic of that in Mediterranean climates, with a winter breeding season which begins when pastures germinate with the initial winter rainfall (April-May) and ceases when the pastures dry out at the end of the year. Unseasonal cyclonic rain can promote pasture growth in summer, leading to limited breeding. At all times of year there were some fertile males, with fewest at the height of summer, followed by an increase before the winter breeding season. Near the coast, male fertility increased more rapidly than further inland. At our two study sites at Cape Naturaliste (on the coast) and Chidlow (55 km inland) the pattern was similar to that in the coastal district. Production of kittens was greater near the coast than further inland, because near the coast there was a high early peak in incidence of pregnancy, a second peak late in the year, and litters remained large throughout the breeding season. In the inland district, the early incidence of pregnancy was lower, there was no second peak, and litter sizes fell at the end of the year. Female reproduction at Cape Naturaliste was typical of that in the coastal district, but that at Chidlow was typical of the inland. The second peak of pregnancy at Cape Naturaliste was due to intensive breeding by subadults born earlier in the year. The differences in female reproduction and productivity between the coastal and inland districts are probably because pasture growth begins earlier and is better in the more fertile coastal areas than in the inland. That nutrition is better for rabbits in the coastal areas than in the inland is reflected in higher growth rates of kittens at Cape Naturaliste than at Chidlow. It is postulated, on the basis of the literature and the results of our studies, that the factor which determines whether rabbits will breed is the presence of growing vegetation, and that the intensity of breeding is influenced by a seasonal cycle in fertility.

Analyses of solute distributions in deeply weathered soils

Methods of analysis of salt distributions in soil profiles are developed and applied to interpret Cl − concentrations observed at 4 forested sites in south-western Australia. Both transient diffusion and steady-state diffusion-convection models are examined. The latter is favoured. The role of diffusion in Cl − transport at 3 of these sites is significant, and in a section of one profile it may dominate convection. Water extraction by roots appears to be restricted to depths of less than 6 m at 3 of the sites with little water moving downwards through the soil at this depth; only 0.06% of average rainfall at the driest site. Maxima in the observed Cl − profiles may result from water movement to greater depths through root channels, or essentially no convection in the lower profile, or a small upward flux of water in the lower region.