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1
Page, Gerald F. M., Louise E. Cullen, Stephen van Leeuwen, and Pauline F. Grierson. "Inter- and intra-specific variation in phyllode size and growth form among closely related Mimosaceae Acacia species across a semiarid landscape gradient." Australian Journal of Botany 59, no. 5 (2011): 426. http://dx.doi.org/10.1071/bt11057.
Повний текст джерелаАнотація:
The mulga complex (Acacia aneura F. Muell ex Benth and closely related species) consists of woody trees and shrubs, and is distributed across 20% of the Australian continent. A. aneura is renowned for a wide variety of phyllode shapes and growth forms, which may co-occur at any one site. We examined the intra- and inter-specific variation in growth form and phyllode shape in four species of the mulga complex, including A. aneura, across topographic gradients in semiarid north-west Australia. We measured 792 trees across 28 sites stratified into six discrete landscape positions; upper slope, lower slope, low open woodland, banded woodland, low woodland, and drainage line. Dominance of phyllode shapes was strongly related to landscape position. A. aneura with terete phyllodes were dominant on the hill slopes, whereas broad phyllodes were most common on A. aneura in all valley woodlands. Trends in growth form were less distinct, although single-stemmed forms were more common on hills, whereas the valleys had more multi-stemmed forms. The quantification of growth form and phyllode shape variability within the mulga complex provides a basis for the quantitative determination of functional links between morphology and environmental conditions at both the site and landscape level.
2
McMeniman, NP, IF Beale, and GM Murphy. "Nutritional evaluation of south-west Queensland pastures. 1. The botanical and nutrient content of diets selected by sheep grazing on Mitchell grass and mulga/grassland associations." Australian Journal of Agricultural Research 37, no. 3 (1986): 289. http://dx.doi.org/10.1071/ar9860289.
Повний текст джерелаАнотація:
The botanical composition and nutrient content of diets selected by sheep grazing Mitchell grass (Astrebla spp.) and mulga (Acacia aneura)/grassland pastures in south-west Queensland were studied during a four-year period. Forbs, when present in the sward, contributed significantly to the diets on both grassland types. Under drought conditions grasses were the major components of the diets of sheep grazing Mitchell grassland pastures, while under similar conditions on the mulga/grassland pastures at least 35% of the diet was mulga (Acacia aneura); some mulga was present in the diet at all times. In general, the nutrient content of the green leaves of grasses and forbs growing on the mulga/ grassland association was similar, whereas on the Mitchell grass association green forbs had a higher nutrient concentration than did the leaves of green grasses. Both the grasses and forbs on the mulga/ grassland site had lower P and sodium concentrations than those on the Mitchell grassland site. When seasonal conditions were average to good the concentrations of all nutrients in the diets of sheep grazing the Mitchell grass association were judged to be adequate. However, when the pastures dried out the diets contained low concentrations of N (7.0 g/kg DM), P (0.9 g/kg DM), sodium (O.lg/kg DM) and copper (3.8 mg/kg DM). On the mulga/grassland site dietary concentrations of P and sodium were low at all times and under drought conditions the N:S ratio fell to 16.8:1. The concentrations of other nutrients in the diets were high enough to provide the sheep's theoretical requirements at all times.
3
Dastlik, KA, EL Ghisalberti, BW Skelton, and AH White. "Structural Study of (-)-8-Epi-11-nordriman-9-one." Australian Journal of Chemistry 44, no. 1 (1991): 123. http://dx.doi.org/10.1071/ch9910123.
Повний текст джерелаАнотація:
The structure of the title compound (1) has been determined by X-ray crystallographic methods. This compound, not previously described as a natural compound, has been isolated from two varieties of the mulga Acacia aneura. Some points of confusion in the literature regarding spectral parameters assigned to (1) are clarified.
4
Brown, RF. "The growth and survival of young Mulga (Acacia aneura F. Muell) trees under different levels of grazing." Rangeland Journal 7, no. 2 (1985): 143. http://dx.doi.org/10.1071/rj9850143.
Повний текст джерелаАнотація:
The effects on the survival and growth of young mulga trees exposed to five levels of sheep graztng were monitored over bur years. The levels ranged from complete exclusion of domest~c stock to continuous grazing at a projected annual consumption rate of 20%, 35%, 50%, or 80% of the total available forage (grass, herbage, and accessible mulga leaf). Innially, all trees were less than 90 cm tall. Four years later, the ungrazed trees had more than doubled in he~ght whereas thegrazed trees were not significantly taller, irrespective of grazing intensity. Over 90% of the ungrazed trees had grown above the upper limit of sheep browsing (I20 cm) and their growth was considered unlikely to be prejudiced by subsequent grazing. Stem diameters nearly trebled in ungrazed mulga but much smaller Increases (averagmg25%) occurred in grazed plants. Overall, 36% of the young trees died. Most deaths occurred during the winter of 1980 and summer of 1982183 after protracted periods of dry weather. Grazing had little or no e,ffect on death rates. Even the lightest grazing arrested mulga growth and prevented the transition from low mulga to the tailer forms used for drought feeding. This is discussed as a possible cause of reported declines in drought reserves of mulga. The results of this study illustrate the need to ensure that grazing strategy is compatible with uninterrupted replacement of umbrella mulga (5-8 m high) cut for drought fodder.
5
Noble, JC. "Relict Surface-Soil Features in Semi-Arid Mulga (Acacia Aneura) Woodlands." Rangeland Journal 15, no. 1 (1993): 48. http://dx.doi.org/10.1071/rj9930048.
Повний текст джерелаАнотація:
The physical dimensions and locations of two forms of circular surface-soil features, believed to be constructed by animals now locally extinct, are described for a 200 ha site and its environs in a semi- arid mulga (Acacia mura) woodland in north-western New South Wales. The most common were 48 circular (c. 10 m diameter) features, some with well-defined central depressions carrying vigorous grass tussocks. Soil chemical analysis indicated the relatively high fertility of these central depressions. Surface pebbles were analysed for comparison with similar lithological data in the literature. The evidence suggests that the malleefowl (Leipoa ocerlata) is the most likely agent responsible for building these features. While only four of the larger features (c. 30 m diameter) were located in the study site, they were particularly conspicuous on higher ridges in adjoining paddocks because of the abundance of highly reflective, calcrete fragments visible on the surface of subcircular mounds. It is postulated that they were constructed by the bumowing bettong (Bettongia lesueur).
6
Recher, Harry F., and William E. Davis Jr. "Foraging Ecology of a Mulga Bird Community." Wildlife Research 24, no. 1 (1997): 27. http://dx.doi.org/10.1071/wr96052.
Повний текст джерелаАнотація:
Mulga is a distinctive woodland or shrub community with a wide distribution across the semi-arid zone of southern and central Australia. Mulga (Acacia aneura) is the dominant shrub and small tree, but other species of Acacia are common. Typical of Australian habitats in the arid zone, mulga has a core of resident bird species that is augmented by nomadic (opportunistic) species when conditions are favourable. This paper describes the foraging behaviour and habitat use of a mulga avifauna in the vicinity of Alice Springs during late winter, when many opportunistic species were present. Data were obtained for 24 species, of which 16 were confirmed as nesting. Many birds, regardless of their normal foraging habits, converged on a common food resource: a geometrid moth (Geometridae) that was abundant on mulga plants. Despite their use of a common food resource, species differed in their foraging behaviour, proportions of different substrates used, and foraging heights. Ground-foraging species dominated the avifauna, but in most respects the guild structure of the community was a scaled-down version of Eucalyptus forest avifaunas. Differences in guild structure between mulga and eucalypt forest are best explained by differences between the two habitats in the kinds of resources (e.g. foraging substrates, types of food) that are available.
7
Silcock, J. L., J. Drimer, J. Fraser, and R. J. Fensham. "Inability of fire to control vegetation dynamics in low-productivity mulga (Acacia aneura)-dominated communities of eastern Australia." International Journal of Wildland Fire 26, no. 10 (2017): 896. http://dx.doi.org/10.1071/wf17011.
Повний текст джерелаАнотація:
Reduced fire frequency and severity associated with livestock grazing are cited as a cause of woody plant encroachment and thickening in rangelands, but such paradigms are difficult to test experimentally owing to limited opportunities to burn. Mulga (Acacia aneura) dominates 25% of the Australian continent and epitomises this quandary. We measured the effect of rare wildfires on tree and shrub mortality and subsequent regeneration in mulga-dominated communities to critically examine prevailing but unsubstantiated paradigms of vegetation structural change. Mortality of mature mulga trees was positively correlated with fire severity, which was negatively correlated with tree basal area per hectare. High-severity fires killed the majority of mulga, but only occurred in more open areas, whereas low-severity fires typical of many mulga communities did not kill substantial proportions of mature mulga. The majority of mulga saplings were killed across all sites regardless of fire severity. Seedling germination was stimulated by fire, but not dependent on it. Green turkey bush (Eremophila gilesii) was the only shrub species with >50% mortality across all sites. Combined with the rarity of fire events in the historical record, our results, particularly limited fire mortality and enhanced post-fire seedling recruitment, suggest that the role of fire in shaping vegetation structure in mulga-dominated communities has been overstated. The decoupling of fire and vegetation structure is consistent with emerging regional studies in low-productivity semiarid environments.
8
Sinclair, R. "Persistence of dead trees and fallen timber in the arid zone: 76 years of data from the T.G.B. Osborn Vegetation Reserve, Koonamore, South Australia." Rangeland Journal 26, no. 1 (2004): 111. http://dx.doi.org/10.1071/rj04008.
Повний текст джерелаАнотація:
Very little information is available about how long dead trees remain standing, or fallen logs persist, in the Australian arid zone. Data on dead timber longevity were extracted from records of both permanent quadrats and photopoints on the T.G.B. Osborn Vegetation Reserve on Koonamore Station, South Australia. Two species were examined, Acacia aneura (mulga) and Myoporum platycarpum (false sandalwood, sugarwood). Some individuals of mulga are capable of standing dead for over 75 years, while dead M. platycarpum may stand for over 60 years. Dead Myoporum trees remained standing for an average of 31.2 � 5.7 years, fallen trunks persisted for 38.4 � 3.7 years. Standing dead A. aneura persisted on average for 40.0 � 3.7 years, fallen trunks for 22.4� 6.3 years. These figures are almost certainly underestimates. The reasons why are discussed and some comparisons made with temperate forests and tropical mangroves.
9
Miller, SM, JD Brooker, and LL Blackall. "A feral goat rumen fluid inoculum improves nitrogen retention in sheep consuming a mulga (Acacia aneura) diet." Australian Journal of Agricultural Research 46, no. 8 (1995): 1545. http://dx.doi.org/10.1071/ar9951545.
Повний текст джерелаАнотація:
Rumen micro-organisms which are resistant to high levels of condensed tannins (CT) may constitute a unique response by feral goats to the nutritive depressing effects of mulga (Acacia aneura) CT. Transferring these micro-organisms to domestic livestock lacking this response may be beneficial when CT-rich mulga diets are consumed. Three experiments were conducted in which sheep consuming a mulga diet were given a ruminal inoculation of feral goat rumen fluid (FGRF). Feed intake and nitrogen (N) retention were significantly greater (P < 0.05) in both sheep and domestic goats following inoculation and in inoculated compared with uninoculated sheep. Inoculation also improved N digestibility and reduced the rate of liveweight loss in sheep and domestic goats. These improvements were of similar magnitude to those attributable to the traditional N, phosphorus and sulfur mineral supplement for mulga fed sheep. FGRF inoculated sheep also grew as much wool as uninoculated sheep receiving a production enhancing mineral supplement. The results from these experiments suggest that FGRF is readily transferable to sheep and improves N metabolism in these animals. Using micro-organisms from FGRF as an inoculum for sheep consuming a mulga diet has the potential to be an alternative to mineral supplements.
10
Andrew, Rose L., Joseph T. Miller, Rod Peakall, Michael D. Crisp, and Randall J. Bayer. "Genetic, cytogenetic and morphological patterns in a mixed mulga population: evidence for apomixis." Australian Systematic Botany 16, no. 1 (2003): 69. http://dx.doi.org/10.1071/sb01043.
Повний текст джерелаАнотація:
The mulga complex (Acacia aneura and closely related taxa) is a widespread group that is dominant in much of arid Australia. The group is taxonomically difficult, due to a complex interaction of sympatry and putative hybridisation between the major species, geographic variation within species and sympatric variation within A. aneura. Mulga is highly variable in a wide range of vegetative and reproductive characters and it is not unusual to find five or six distinct forms growing side by side. The aim of this project was to gain a better understanding of the relationships among mulga species and A. aneura varieties, as well as the maintenance of this variation. A single site in the Northern Territory, containing A. ayersiana, A. minyura and two varieties of A. aneura, was sampled intensively. Six morphotypes were observed in the field and five were strongly supported by morphometric analysis. Although the mulga complex is generally tetraploid (2n = 52), triploid (2n = 39) and pentaploid (2n = 65) seedlings were produced in the study population. Microsatellite primers developed for A. mangium (sect. Juliflorae) were amplified in individuals of each morphotype, resulting in genetic marker patterns consistent with polyploidy. Genetic and morphometric distances were correlated and differences between morphotypes account for 63% of the total genetic variation (ΦPT = 0.63, P < 0.001). Allele sequences confirmed the presence of genuine heterozygosity and clonality was suggested by the low genotypic diversity and the lack of allele segregation. Seedlings had identical genotypes to the maternal plants and polyembryony was observed in each taxon, consistent with apomictic reproduction. Both variation of the ploidy level and apomixis may restrict gene flow among morphotypes, playing a role in the maintenance of morphological diversity at the study site. The success of the group in arid and semi-arid Australia may also be due, in part, to these factors.
11
Miller, S. M., D. A. Pritchard, S. J. Eady, and P. R. Martin. "Polyethylene glycol is more effective than surfactants to enhance digestion and production in sheep fed mulga (Acacia aneura) under pen and paddock conditions." Australian Journal of Agricultural Research 48, no. 8 (1997): 1121. http://dx.doi.org/10.1071/a96127.
Повний текст джерелаАнотація:
Chemicals that interfere with the formation of tannin-protein complexes were evaluated as dietary additives for mulga-fed sheep in pens and under paddock conditions. Condensed tannins (CT) in mulga inhibit protein digestion, and the use of chemicals to precipitate CT or dissociate CT-protein complexes may improve production from sheep consuming a mulga diet. In a digestion study with mulga-fed sheep in pens, provision of polyethylene glycol (PEG) at a rate of 6 g/day significantly (P < 0·05) improved nitrogen (N), phosphorus (P), and sulfur (S) balance, and apparent N, P, dry matter (DM), and organic matter digestibility, and the rate of liveweight gain. Addition of the surfactants SDS or alkanate 3SL3 to the diet of mulga-fed sheep did not improve N balance or digestion; however, apparent digestibility of P, and P and S balance, were significantly improved by SDS. Teric PE64, a compound structurally similar to PEG, significantly improved S balance, but not DM intake or N balance. For sheep consuming a predominantly mulga diet under paddock conditions, provision of PEG at a rate of 12 g/day significantly improved clean wool growth and liveweight gain compared with unsupplemented sheep, by 9% and 100%, respectively (0·809 v. 0·745 mg/cm2.day, and 44 v. 22 g/day). The studies demonstrated that although surfactants can affect mulga digestion, using PEG to precipitate CT is more effective to improve mulga digestion and animal production than the use of surfactants. However, the wool and liveweight production responses achieved with PEG were not sufficient to justify its wide-scale use for mulga-fed sheep. Consequently, alternative methods should be sought to reduce the negative effects of mulga CT on sheep production.
12
Ward, Bruce G., Thomas B. Bragg, and Barbara A. Hayes. "Relationship between fire-return interval and mulga (Acacia aneura) regeneration in the Gibson Desert and Gascoyne–Murchison regions of Western Australia." International Journal of Wildland Fire 23, no. 3 (2014): 394. http://dx.doi.org/10.1071/wf13007.
Повний текст джерелаАнотація:
A study of 26 burnt mulga (Acacia aneura) stands was conducted from 2003 to 2012 in the Gibson Desert and eastern Gascoyne–Murchison region of Western Australia to assess the effect of fire interval on seedling regeneration. Tree-ring analysis and Landsat satellite imagery identified mulga stands with fire intervals ranging from 3 to 52 years. Results show fire-return intervals less than 20 years produce 2–3-year-old seedling regeneration lower than 50% of the original adult stand population (average juvenile-to-adult ratio=0.49). In total, 6 of the 26 stands sampled had reburnt within 3 to 10 years of the previous burn, a consequence of increased plant growth associated with higher rainfall. For all fires, summer fires were larger and more frequent (24 of 35 fires recorded, median fire size=150km2) than spring fires (median fire size=91km2). This study emphasises the important role of fire in maintaining the diversity and vigour of the mulga–Triodia ecosystem but indicates a minimum fire-return interval of 26 years to maintain mulga populations.
13
Turner, J. C., M. H. Friedel, and M. Neumann. "Phyllode fall and nutrient content in a mulga (Acacia aneura F.Muell. ex Benth.) community in central Australia in response to rainfall." Rangeland Journal 43, no. 1 (2021): 1. http://dx.doi.org/10.1071/rj21007.
Повний текст джерелаАнотація:
The fall of phyllodes from Acacia aneura F.Muell. ex Benth. (mulga) in central Australia was studied over 22 months from mid-1958 at four locations within a livestock reserve north of Alice Springs in the Northern Territory, in order to identify rainfall or seasonal triggers. Phyllode fall increased by at least an order of magnitude for short periods following rain of 15–20mm or more on a ‘mature’ mulga site and similar trends were apparent for ‘young’ and ‘desert form’ mulga on the same site, and on a second, independent, ‘mature’ site. When rates of phyllode fall were high after substantial rain, at both ‘mature’ locations, ~30% of nitrogen and ~50% of phosphorus were withdrawn before abscission, suggesting that mulga was markedly conservative of these nutrients. Conversely, under dry conditions, when phyllode fall was relatively low (<200mgm−2day−1), concentrations of nitrogen and phosphorus in fallen phyllodes were higher. Concentrations of potassium, calcium, magnesium and sodium did not vary consistently with increasing rate of phyllode fall, although overall levels of calcium and potassium were considerably higher in the second ‘mature’ location. This legacy study is of renewed interest given the potential of mulga communities to contribute to national carbon stocks, and the consequent need for robust field-based data on growth dynamics and carbon fluxes.
14
Fensham, Roderick J., Owen Powell, and James Horne. "Rail survey plans to remote sensing: vegetation change in the Mulga Lands of eastern Australia and its implications for land use." Rangeland Journal 33, no. 3 (2011): 229. http://dx.doi.org/10.1071/rj11007.
Повний текст джерелаАнотація:
There is a prevailing paradigm that woody vegetation is expanding at the expense of grassland with reduced burning under pastoralism in the Mulga Lands biogeographic region in eastern Australia. This raises the possibility that the region is acting as a carbon sink. Vegetation boundaries were precisely positioned from rail survey plans dating from 1895 to 1900. This baseline was compared with the position of boundaries on 1952 aerial photography and 2010 Google Earth imagery. The conversion of forest to non-forest by mechanical clearing was also mapped from satellite imagery. There was no consistent trend in the direction of boundary movement for mulga (Acacia aneura F.Muell. ex Benth.), gidgee (Acacia cambagei R.T. Baker) forest or miscellaneous other forest types. The stability of the boundaries, despite the transition from aboriginal management to rangeland pastoralism, contrasts with dramatic declines in tree cover resulting from mechanical clearing. Mapping of forest cover from satellite imagery reveals that conversion of forest to non-forest has reduced mulga forest to 74%, gidgee forest to 30% and miscellaneous forest types to 82% of their original area. Annual clearing rates for the period between 1997 and 2005 were 0.83, 0.95 and 0.43% for those forest types, respectively. Clearing has declined substantially in the period 2005–09 since the advent of recent regulations in Queensland. The area remains a source of carbon emissions but this situation may reverse if restoration of mulga dry forest becomes an attractive land use with an emerging carbon market.
15
Dalal, R. C., B. P. Harms, E. Krull, W. J. Wang, and N. J. Mathers. "Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping. 2. Total and labile nitrogen." Soil Research 43, no. 2 (2005): 179. http://dx.doi.org/10.1071/sr04076.
Повний текст джерелаАнотація:
Mulga (Acacia aneura) woodlands and open forests occupy about 150 Mha in Australia, and originally occupied 11.2 Mha in Queensland. Substantial areas (1.3 Mha) of the mulga vegetation have been cleared in Queensland, mostly for pasture production, but some areas are also used for cereal cropping. Twenty years after mulga clearing we found a significant loss of total soil organic C (28–35% from the 0–0.05 m depth) and light fraction C (>50% from the 0–1 m depth) from soil under pasture and cropping at a site in southern Queensland. We report here the changes in soil N and labile N pools in a paired-site study following conversion of mulga to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for more than 20 years. Conversion from mulga forest to pasture and cultivation resulted in greater losses of soil N than organic C in the top 0.1 m depths. As a result, C/N ratios in soil under both pasture and cropping were higher than soil under mulga, indicating a decline in soil organic matter quality after mulga clearing. Although land-use change had no significant effect on 15N natural abundance (δ15N) values of total soil N down to a depth of 1 m, δ15N values of wheat tops and roots indicated that the primary source of N under cropping was soil organic N, while that of buffel pasture was a mixed source of soil N and decomposed litter and root N. Light fraction N (<1.6 Mg/m3) declined by 60–70% throughout the 1 m soil profile under pasture and cropping, but it was 15N-enriched in these 2 land-use systems. The δ15N values of mulga phyllodes, twigs, and fine roots, indicated an input of atmospheric fixed N2 that was estimated to be about 25 kg N/ha.year. However, the source and magnitude of this N resource needs to be confirmed. Soil N losses were estimated to be 12 kg N/ha.year under pasture and 17 kg N/ha.year under cropping over a 20-year period. These findings raise the issue of the long-term sustainable use of cleared mulga areas for pasture and/or cropping. The labile C and N pools and N mineralised also declined, which would have an immediate adverse effect on soil fertility and plant productivity of cleared Mulga Lands, as well as reducing their potential as a soil sink for greenhouse gases.
16
Pritchard, DA, PR Martin, and PK O'Rourke. "The role of condensed tannins in the nutritional value of mulga (Acacia aneura) for sheep." Australian Journal of Agricultural Research 43, no. 8 (1992): 1739. http://dx.doi.org/10.1071/ar9921739.
Повний текст джерелаАнотація:
Sheep were fed mulga (Acacia aneura) ad libitum and supplemented with 0, 12 or 24 g/day of polyethylene glycol molecular weight 4000 (PEG), with or without an additional supplement of 1.5 g/day of each of nitrogen (N), phosphorus (P) and sulfur (S) (NPS). Supplementation with either 12 g/day PEG or 24 g/day PEG increased dry matter intake by 56 and 78% respectively and clean wool growth per unit surface area by 166 and 178% respectively. Supplementation with 24 g/day PEG increased wool fibre diameter, linear growth rate and volumetric growth rate by 32, 29 and 143% respectively. Sheep receiving 24 g/day PEG retained more N (1.80 g/day) and S (254 mg/day) and digested more N (218 g/kg) and S (229 g/kg) when compared with non-supplemented animals. These parameters were further enhanced when NPS was supplemented in conjunction with 24 g/day PEG. Maximum precipitation (77%) of mulga condensed tannins (CT) occurred at a PEG to CT ratio of 0.7:l.
17
Dalal, R. C., B. P. Harms, E. Krull, and W. J. Wang. "Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping 1. Total and labile carbon." Soil Research 43, no. 1 (2005): 13. http://dx.doi.org/10.1071/sr04044.
Повний текст джерелаАнотація:
Mulga (Acacia aneura) dominated vegetation originally occupied 11.2 Mha in Queensland, of which 12% has been cleared, mostly for pasture production, but some areas are also used for cereal cropping. Since mulga communities generally occupy fragile soils, mostly Kandosols and Tenosols, in semi-arid environments, clearing of mulga, which continues at a rate of at least 35 000 ha/year in Queensland, has considerable impact on soil organic carbon (C), and may also have implications for the greenhouse gas emissions associated with land use change in Australia. We report here the changes in soil C and labile C pools following mulga clearing to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for 20 years in a study using paired sites. Soil organic C in the top 0.05 m of soil declined by 31% and 35% under buffel pasture and cropping, respectively. Land use change from mulga to buffel and cropping led to declines in soil organic C of 2.4 and 4.7 t/ha, respectively, from the top 0.3 m of soil. Using changes in the δ13C values of soil organic C as an approximate representation of C derived from C3 and C4 vegetation from mulga and buffel, respectively, up to 31% of soil C was C4-derived after 20 years of buffel pasture. The turnover rates of mulga-derived soil C ranged from 0.035/year in the 0–0.05 m depth to 0.008/year in the 0.6–1 m depths, with respective turnover times of 29 and 133 years. Soil organic matter quality, as measured by the proportion/amount of labile fraction C (light fraction, < 1.6 t/m3) declined by 55% throughout the soil profile (0–1 m depth) under both pasture and cropping. There is immediate concern for the long-term sustainable use of land where mulga has been cleared for pasture and/or cropping with a continuing decline in soil organic matter quality and, hence, soil fertility and biomass productivity. In addition, the removal of mulga forest over a 20-year period in Queensland for pasture and cropping may have contributed to the atmosphere at least 12 Mt CO2-equivalents.
18
Anderson, Val Jo, and Ken C. Hodgkinson. "Grass-mediated Capture of Resource Flows and the Maintenance of Banded Mulga in a Semi-arid Woodland." Australian Journal of Botany 45, no. 2 (1997): 331. http://dx.doi.org/10.1071/bt96019.
Повний текст джерелаАнотація:
It has been proposed for semi-arid and arid regions that the scarce resources of water and nutrients normally limiting plant growth are distributed patchily in the landscape in order to maintain both stability and productivity (Tongway 1990). ‘Fertile patches’ are maintained by the concentration of resources during flows and when resource control is weakened their persistence is threatened. This proposition was tested by comparing water relations of perennial life-forms in the nutrient and water rich ‘island-bands’ of mulga (Acacia aneura F.Muell. ex Benth.) shrubs, with and without perennial grasses. Dawn xylem water potential (dawn ψx) and stable hydrogen isotope composition data showed that A. aneura and companion grasses competed for soil water, whereas the poplar box (Eucalyptus populnea F.Muell.) trees accessed additional sub-soil water. During a drying cycle, dawn ψx of A. aneura on the upslope portion of ‘island-bands’ was –2 MPa where grass was abundant, and –4.8 MPa where grasses were killed by heavy grazing. On the downslope portions, dawn ψx of A. aneura was similar at –4.2 MPa. Recruitment of A. aneura was occurring in the upslope portion, but was less where there were no grasses. There were more dead A. aneura shrubs on the downslope portion and in grass-free ‘island-bands’. The results suggest that removal of perennial grasses by grazing shortens the period of water supply to A. aneura shrubs in ‘island-bands’ and they prematurely die during low rainfall periods. Furthermore, continued grazing pressure from domestic and non-domestic herbivores will prevent restoration of landscape processes necessary for the survival of these shrubs and associated flora.
19
Silcock, J. L., G. B. Witt, and R. J. Fensham. "A 150-year fire history of mulga (Acacia aneura F. Muell. ex Benth.) dominated vegetation in semiarid Queensland, Australia." Rangeland Journal 38, no. 4 (2016): 391. http://dx.doi.org/10.1071/rj15109.
Повний текст джерелаАнотація:
Changes to fire regimes associated with European colonisation are implicated in declines in biodiversity and productivity in rangelands globally. However, for many areas there is incomplete knowledge of historical fire regimes and purported changes can become accepted wisdom with little empirical evidence. In the Mulga Lands of south-western Queensland, the dominant narrative implicates reduced fire frequency as a cause of woody vegetation thickening. We present a fire history of the Mulga Lands since pastoral exploration in the 1840s based on a review of explorer and early pastoralist journals, newspaper articles, interviews with long-term landholders and collation of satellite imagery. Fires in mulga communities are infrequent and only occur after at least two years of above-average summer rainfall. The assumption of regular pre-pastoral fires is not supported by available evidence. Since pastoral settlement in the 1860s, fire events affecting >1000 km2 have occurred seven times (1891–1892, 1904, 1918, 1950–1951, 1956–1957, 1976–1979 and 2011–2013), with only the 1950s fires affecting a >10% of the total area of mulga-dominated vegetation. We argue that fire is limited by fuel loads, which are in turn limited by rainfall events occurring only a few times a century. Even in the absence of grazing and active fire suppression fire intervals would be extremely long, perhaps 30–50 years in relatively fire-prone communities and much longer throughout most of the region. Combined with quantitative studies of fire and tree and shrub population dynamics, detailed fire histories will allow for more informed and nuanced debates about the role of fire in rangelands subject to abrupt management upheavals.
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FENSHAM, R. J., J. M. DWYER, T. J. EYRE, R. J. FAIRFAX, and J. WANG. "The effect of clearing on plant composition in mulga (Acacia aneura) dry forest, Australia." Austral Ecology 37, no. 2 (June 16, 2011): 183–92. http://dx.doi.org/10.1111/j.1442-9993.2011.02261.x.
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Miller, SM, JD Brooker, A. Phillips, and LL Blackall. "Streptococcus caprinus is ineffective as a rumen inoculum to improve digestion of mulga (Acacia aneura) by sheep." Australian Journal of Agricultural Research 47, no. 8 (1996): 1323. http://dx.doi.org/10.1071/ar9961323.
Повний текст джерелаАнотація:
This study examined the distribution of Streptococcus caprinus in domestic and feral ruminants, and the effect of rumen inoculation with S. caprinus on nitrogen digestion in mulga-fed sheep. S. caprinus is a tannin-resistant rumen bacterium found in feral goats and may play a role in alleviating the nutritive depressing effects of high concentrations of plant tannins in these animals. S. caprinus was present in samples of rumen fluid from feral goats and feral camels but was not detectable in rumen fluid from sheep and domestic goats that had not previously grazed forages containing condensed tannins. A proportion of sheep, domestic goats, and cattle grazing in mulga paddocks, with either feral goats or camels, had detectable populations of S. caprinus. Pure cultures of S. caprinus grown in vitro were successfully placed in the rumen of sheep; however, nitrogen digestion was unaffected by rumen inoculation. Interactions between several populations of micro-organisms may therefore be involved in achieving improvements in protein digestion.
22
Ryan, SA, KE Moseby, and DC Paton. "Comparative foraging preferences of the greater stick-nest rat Leporillus conditor and the European rabbit Oryctolagus cuniculus: implications for regeneration of arid lands." Australian Mammalogy 25, no. 2 (2003): 135. http://dx.doi.org/10.1071/am03135.
Повний текст джерелаАнотація:
Dietary preferences of the greater stick-nest rat (Leporillus conditor) and the European rabbit (Oryctolagus cuniculus) were compared using cafeteria trials and direct observations. Despite overlap, these species exhibited differences in dietary preference. L. conditor showed a strong preference for chenopod shrub species and other plant species with a high water content including Gunniopsis quadrifida and Calandrinia remota. L. conditor also preferred female bladder saltbush (Atriplex vesicaria) foliage to male. O. cuniculus ate a greater selection of plant species in most trials with their most preferred species including mulga (Acacia aneura), Salsola kali and Calandrinia remota. Both O. cuniculus and L. conditor preferred seedlings of perennial species to adult cuttings. L. conditor has recently been re-introduced to a 14 km� O. cuniculus, cat (Felis catus) and red fox (Vulpes vulpes) proof exclosure in the arid zone of South Australia. The re-introduction of this herbivore and the removal of exotic herbivores may change the vegetation structure and composition within the exclosure by restricting growth of some succulent chenopod species but allowing the regeneration of tall shrub species such as Acacia aneura which are usually limited by O. cuniculus grazing.
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Recher, Harry F. "Foraging behaviour of mulga birds in Western Australia. II. Community structure and conservation." Pacific Conservation Biology 24, no. 1 (2018): 87. http://dx.doi.org/10.1071/pc17032.
Повний текст джерелаАнотація:
Mulga (Acacia aneura) woodlands dominate much of arid and semiarid Australia. Although mulga woodlands are floristically and structurally diverse, the composition of the mulga avifauna is consistent across the continent, with 50–70% of bird species shared between sites and a high proportion of migratory and nomadic species. A comparison of avian foraging guilds in mulga woodlands in the Murchison and Gascoyne Bioregions of Western Australia with those in the Northern Territory identified nine guilds. All guilds occurred at the three locations studied during wet years. The number of bird species, species’ abundances, and the number of guilds declined on the Western Australian sites when there was less rain. Despite the commonality of guilds and species between sites, there were differences between sites and years in the grouping of species, with many species best associated with two or more guilds. These differences reflected differences between locations and wet and dry years in the food resources available to birds, which affected how species foraged. Particularly noticeable were the differences between sites and years in migratory and nomadic birds, which in Western Australia and the Northern Territory were the most abundant birds during wet conditions, but largely absent when conditions were drier.
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Nicholas, Anstee M. M., Donald C. Franklin, and David M. J. S. Bowman. "Coexistence of shrubs and grass in a semi-arid landscape: a case study of mulga (Acacia aneura, Mimosaceae) shrublands embedded in fire-prone spinifex (Triodia pungens, Poaceae) hummock grasslands." Australian Journal of Botany 57, no. 5 (2009): 396. http://dx.doi.org/10.1071/bt07157.
Повний текст джерелаАнотація:
The persistence of relatively fire-sensitive mulga (Acacia aneura F.Muell. ex Benth., Mimosaceae) shrublands within a landscape matrix of highly flammable spinifex (Triodia spp. R.Br., Poaceae) hummock grassland is a central question in the ecology of semiarid Australia. It is also a special case of questions about the coexistence of grasses and woody plants that have general application in semiarid rangelands and tropical savannas. With the use of field surveys and a 24-year fire history, we examined their coexistence on a sandplain in the Tanami Desert, Northern Territory, Australia. Mulga and spinifex each formed discrete monodominant stands with generally abrupt boundaries that did not correspond to obvious edaphic or topographic discontinuities. Spinifex hummock grasslands burnt almost three times as often as mulga shrublands and tended to occur on lighter soils with less biological crusting and more physical soil crusting. A combination of fire and soil variables described the environmental partitioning better than did either alone. Biological crusting increased with time since fire in both vegetation types. The demographic structure of mulga stands reflected their fire history, the more frequently burnt stands comprising almost entirely small plants. One fifth of mulga plants <0.5 m tall were resprouts. Our data provide support for the hypothesis that abrupt boundaries between mulga shrublands and spinifex hummock grasslands can be generated across diffuse environmental gradients by fire–soil–vegetation feedback loops. The oft-severe demographic impact of fire on mulga that is burnt raises questions about the appropriateness of frequent intense fires in this landscape.
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Bennison, Kerrie, Christopher R. Dickman, and Robert Godfree. "Habitat use and ecological observations of the Ooldea dunnart (Sminthopsis ooldea) at Uluru–Kata Tjuta National Park, Northern Territory." Australian Mammalogy 35, no. 2 (2013): 175. http://dx.doi.org/10.1071/am12048.
Повний текст джерелаАнотація:
The Ooldea dunnart (Sminthopsis ooldea) is a small (10–11 g) and poorly known dasyurid marsupial that is endemic to the central and western arid regions of Australia. Surveys carried out at Uluru–Kata Tjuta National Park, Northern Territory, from 1994 to 2010 yielded 37 captures of this elusive species, providing novel insights into its biology. Most captures were made in pitfall traps, with spring breeding confirmed by the presence of pregnant or lactating females during October and November. Animals were captured in mallee and mulga woodland and spinifex (Triodia spp.) dominated dune fields and sand plains. Capture rates were variable in most habitat types, but were relatively consistent in one site dominated by mulga (Acacia aneura). Although we found no consistent association between captures of S. ooldea and prior rainfall, fewest animals were captured in the two wettest years of the study. Ooldea dunnarts showed no clear response to fire. We suggest that mulga is a key habitat for S. ooldea, but also that the demography of this species may be shaped by biotic and/or abiotic factors that remain to be fully elucidated.
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Leavesley, Adam J., Geoffrey J. Cary, Glenn P. Edwards, and A. Malcolm Gill. "The effect of fire on birds of mulga woodland in arid central Australia." International Journal of Wildland Fire 19, no. 7 (2010): 949. http://dx.doi.org/10.1071/wf09028.
Повний текст джерелаАнотація:
The principal ecosystem driver in arid Australia is unpredictable rainfall, but it is hypothesised that fire also plays an important role in determining the distribution of animals. We investigated the effect of fire on birds in mulga (Acacia aneura) woodland in the central Australian arid zone. The study was conducted at Uluru–Kata Tjuta National Park using 63 sites classified into one of three time-since-fire classes: burnt 2002; burnt 1976; and long-unburnt. Birds were sampled in the winter and spring of 2005 and 2006 and vegetation structure was measured at all sites. Vegetation structure varied with time-since-fire. The burnt 2002 treatment was an early seral stage of mulga woodland and effectively a grassland. The burnt 1976 and long-unburnt treatments were both woodland, but the long-unburnt treatment had greater canopy cover and height. The bird community in the burnt 2002 treatment was characterised by granivores, whereas that in the burnt 1976 and long-unburnt treatments was characterised by foliar insectivores. All species showed monotonic responses to time-since-fire (i.e. none were at significantly highest density in the burnt 1976 treatment). Fire in mulga woodland changed the vegetation structure and consequently also changed the composition of the bird communities.
27
Greene, RSB. "Soil physical properties of three geomorphic zones in a semiarid mulga woodland." Soil Research 30, no. 1 (1992): 55. http://dx.doi.org/10.1071/sr9920055.
Повний текст джерелаАнотація:
Soil physical properties were measured in three contiguous geomorphic zones of a patterned sequence of alternating groves and intergroves in a semi-arid mulga (Acacia aneura) woodland : (1) a runoff zone of stony, severely sealed, surface soil, (2) an interception zone at the bottom of the runoff zone, and adjoining (3) a runon zone of mulga groves. Infiltration was measured in the field under unsaturated and saturated conditions using a disc permeameter at water supply potentials of -40 and +10 mm respectively. Under unsaturated flow conditions, there were no significant differences in the sorptivity, three-dimensional infiltration rate and hydraulic conductivity between the three zones. However, under saturated flow conditions, the soils in the mulga groves had infiltration rates 5-10 times higher than the soils in the runoff and interception zones. This difference was explained by the presence of stable macropores >0.75 mm diameter in the mulga grove soils. Surface soil (0-10 mm) aggregates from mulga groves were also particularly stable to rapid wetting, measured by wet-sieving. Volumetric water contents (measured over a range of matric potentials from 0 to -5.0 kPa) of the 0-50 mm layer of soil from the mulga grove and interception zone were significantly (P = 0.05) higher than the 0-50 mm layer from the runoff zone. Micromorphological and scanning electron microscope (SEM) examination indicated that the total porosity of the soil surface from the mulga groves and interception zones was greater than that of the runoff zones. Measurement of soil-water content following a major rainfall event indicated that water had flowed off the runoff zones and accumulated in the mulga groves. These findings are consistent with the higher herbage production and biotic activity that is found to occur in the mulga grove and interception zone compared with the runoff zone following adequate rainfall. They also reveal part of the delicate balance of runoff redistribution in grove/intergrove areas and the potential for management to alter this balance.
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Leavesley, Adam J., and Geofferey J. Cary. "The effect of patch area on birds in central Australian mulga (Acacia aneura) woodland of different times-since-fire." Pacific Conservation Biology 19, no. 1 (2013): 28. http://dx.doi.org/10.1071/pc130028.
Повний текст джерелаАнотація:
It is often assumed that a fine-scaled mosaic of different times-since-fire supports greater biodiversity than a coarsescaled mosaic — the fire mosaic hypothesis. A potential mechanism of the fire mosaic hypothesis is the effect of area on species diversity. We investigated the effect of patch area on bird communities in mulga (Acacia aneura) woodland in central Australia. The study was conducted at Uluru Kata-Tjuta National Park using 55 fixed-area sites classified to the time since last fire: burnt 2002; burnt 1976 and long unburnt. Birds were surveyed in the winter and spring of 2005 and 2006. Of 20 key species, two showed a positive density-area effect (i.e. higher density in larger patches). Patch area did not affect total bird density or species richness. However, species turnover (ß-diversity) was greater in large patches in the burnt 2002 treatment than it was in small patches. There was no effect of patch area on the composition of the bird communities in any of the time-since-fire classes. We concluded that patch area did affect the distribution of some birds in mulga woodland. However, patch area was not a mechanism of the fire mosaic hypothesis because the effects of patch size tended to increase avian diversity in larger patches rather than small.
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Noble, JC, RSB Greene, and WJ Muller. "Herbage Production Following Rainfall Redistribution in a Semi-Arid Mulga (Acacia Aneura) Woodland in Western New South Wales." Rangeland Journal 20, no. 2 (1998): 206. http://dx.doi.org/10.1071/rj9980206.
Повний текст джерелаАнотація:
The effects of stocking rate (nominally ranging from 0.3 up to 0.8 dry sheep equivalents per ha) on rainfall redistribution, soil-water storage and herbage production were studied in three contiguous geomorphic zones (run-off, interception and run-on zones) in a semi-arid mulga (Acacia aneura) woodland in western New South Wales. The amount of rainfall redistribution increased directly with rainfall but there was no significant effect of stocking rate on the amount of soil-water stored in various zones. while soil-water storage differed little between zones following a minor rainfall event (11.9 mm), it was significantly higher (P < 0.001) in the run-on zone following a major rainfall event (42.7 mm). The interception zone was by far the most productive herbage zone contributing a significantly (P < 0.01) disproportionate amount of forage (c. 90% of total paddock production at low stocking rates) despite this zone only occupying a relatively small proportion (c. 12%) of landscape catenae. Herbage in the interception zone principally comprised palatable C3 perennial grasses such as Thyridolepis mitchelliana (mulga grass) and Monachather paradoxa (bandicoot grass). Experimental manipulation confirmed the fundamental importance of rainfall redistribution as a landscape process mediating herbage production in these semi-arid plant communities. Dry matter production by Eragrostis eriopoda (woollybutt) was significantly enhanced (P < 0.05) in the run-off zone when incident rainfall was retained in situ by metal barriers. Conversely, production by Thyridolepis mitchelliana in the lower interception zone was significantly depressed (P < 0.01) where similar barriers prevented access by overland flow. The results are discussed in the context of developing conservative management strategies designed to maintain effective landscape processes in these extensive ecosystems.
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Kirschbaum, Miko U. F., Ben Harms, Nicole J. Mathers, and Ram C. Dalal. "Soil carbon and nitrogen changes after clearing mulga (Acacia aneura) vegetation in Queensland, Australia: Observations, simulations and scenario analysis." Soil Biology and Biochemistry 40, no. 2 (February 2008): 392–405. http://dx.doi.org/10.1016/j.soilbio.2007.09.003.
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31
Schlesinger, Christine A. "Does vegetation cover affect the rate of capture of ground-active lizards in pitfall traps?" Wildlife Research 34, no. 5 (2007): 359. http://dx.doi.org/10.1071/wr06141.
Повний текст джерелаАнотація:
Pitfall traps are commonly used to capture terrestrial vertebrates, but it is not known whether differences in vegetation structure affect the efficiency of these traps. Studies that investigate the effects of fire, grazing or vegetation rehabilitation on faunal populations usually compare sites that differ in vegetation structure and the validity of using pitfall traps to sample populations under these circumstances is open to question. This study tests whether vegetation structure affects the rate at which lizards are captured in pitfall traps by cutting ground vegetation in a controlled experiment conducted in field enclosures. The study was undertaken in an area of mulga (Acacia aneura) shrubland in central Australia. Ground cover, consisting of grasses and forbs, was reduced from ~27% to 10% in treatment enclosures. These levels of cover correspond broadly to the range of ground covers encountered in this habitat, including areas with high and low levels of grazing. No difference was detected in the rate at which lizards were captured in enclosures where grass was cut compared with the control enclosures or rates of capture before grass was cut. These results indicate that pitfall trapping is a valid technique for comparing lizard populations in arid mulga shrublands within the range of vegetation covers used in this study, including areas that are subject to different levels of grazing.
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Munro, Nicola T., Katherine E. Moseby, and John L. Read. "The effects of browsing by feral and re-introduced native herbivores on seedling survivorship in the Australian rangelands." Rangeland Journal 31, no. 4 (2009): 417. http://dx.doi.org/10.1071/rj08027.
Повний текст джерелаАнотація:
Browsing by introduced cattle (Bos taurus) and rabbits (Oryctolagus cuniculus) can limit the recruitment of some arid zone tree and shrub species. In a study conducted at the Arid Recovery Reserve, Roxby Downs, SA, we aimed to quantify initial recruitment changes in shrubs after the removal of cattle and rabbits and the re-introduction of locally extinct fauna. The presence and abundance of seedlings was measured at groves of seven native perennial shrubs over 6 years under four browsing treatments: (1) ‘reserve-reintroductions’ [re-introduced greater stick-nest rats (Leporillus conditor), burrowing bettongs (Bettongia lesueur) and greater bilbies (Macrotis lagotis)], (2) ‘reserve-no browsers’, (3) ‘pastoral-stocked’ (rabbits and cattle), and (4) ‘pastoral-destocked’ (rabbits). Recruitment of mulga (Acacia aneura F.Muell. ex Benth.), silver cassia (Senna artemisioides subsp. petiolaris Randell) and sandhill wattle (Acacia ligulata A.Cunn. ex Benth.) was significantly greater in the two browsing regimes inside the Reserve than in the two pastoral regimes. The number of recruits of these three species declined at ‘pastoral-destocked’ and ‘pastoral-stocked’ sites but increased at ‘reserve-reintroductions’ and ‘reserve-no browsers’ sites from 2001 to 2006. Narrow-leaf hopbush (Dodonaea viscose (L.) Jacq.) showed a trend towards increased recruitment at sites in both browsing regimes inside the Reserve, but decreased recruitment at sites in both pastoral regimes. Native plum (Santalum lanceolatum R.Br.), native apricot (Pittosporum phylliraeoides orth. var. DC.) and bullock bush (Alectryon oleifolius (Desf.) S.T.Reynolds) exhibited no significant difference in recruitment between the four browsing regimes within the study timeframe. These results suggest that excluding rabbits and stock may benefit the germination and survival of mulga, silver cassia and sandhill wattle. To date, re-introduced native herbivores at low numbers have not been found to negatively affect the recruitment or growth rate of the seven perennial plant species studied.
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Brown, RF. "The effects of burning, fertilizing and clipping on populations of Aristida armata, Thyridolepis mitchelliana and Monachather paradoxa in a mulga woodland pasture." Rangeland Journal 8, no. 1 (1986): 4. http://dx.doi.org/10.1071/rj9860004.
Повний текст джерелаАнотація:
The effects of burning, clipping, applying nitrogenous fertilizer, and protection from grazing on populations of three perennial grasses were monitored over four years in permanent quadrats in a mulga (Acacia aneura) woodland pasture near Charleville. Queensland. The grasses were the weedy invader Aristida armata (wiregrass), and two desirable species, Thyridolepis mitchelliana (mulga grass) and Monachather paradoxa (mulga oats). They comprised 70%, 16%, and 12%. respectively, of the pasture at the start of the experiment. Rainfall had a greater effect on plant numbers. especially of A. armata, than any treatment other than repeated clipping. The greatest mortality amongst A. armata plants occurred during a protracted dry period between March 1982 and April 1983 but the losses were more than compensated by mass germination during April 1983. The other two species responded similarly but less markedly. Repeated clipping caused attrition of all three species but failed to improve pasture composition. Pasture recovery after burning was slow and accompanied by a minor deterioration in pasture composition as measured by the proportion of A. armata plants. Burning caused greater mortality in A. armata plants than in the other two species but this was offset by greater A. armata seedling regeneration. Both initial survival and subsequent seedling recruitment were reduced by slashing a week prior to burning. When left ungrazed. T mitchelliana and M. paradoxa were more drought tolerant than A. armata and their relative numbers in the ungrazed plots increased over the four years of the experiment. Thus, protection from grazing offers the best prospect of improving pasture condition as none of the other treatments reduced A. armata numbers without adversely affecting those of T. mitchelliana and M. paradoxa.
34
Williams, Wendy J., and Burkhard Büdel. "Species diversity, biomass and long-term patterns of biological soil crusts with special focus on Cyanobacteria of the Acacia aneura Mulga Lands of Queensland, Australia." Algological Studies 140 (August 2, 2012): 23–50. http://dx.doi.org/10.1127/1864-1318/2012/0059.
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Gardiner, HG. "Dynamics of Perennial Plants in the Mulga (Acacia aneura F. Muell) Zone of Western Australia. I. Rates of Population Change." Rangeland Journal 8, no. 1 (1986): 18. http://dx.doi.org/10.1071/rj9860018.
Повний текст джерелаАнотація:
The dynamics of populations of six plant species and their responses to environmental factors were examined at Yeelirrie station in the Mulga Zone rangelands of Western Australia. Populations of plants were sampled using sequential maps drawn from low level aerial photographs of areas from which livestock had been removed and which were fenced either to exclude or permit grazing by kangaroos (Macropus rufus Desmarest and Macropus robustus Gould). All six plant species were favoured by the combination of wet years (1973-76) and the removal of livestock from these arid rangelands. Increases ranged from about 20 plants/ha/yr (Eremophila leucophylla, Benth.) to more than 700 plants/ha/yr (Eremophila spectabilis, C.A. Gardn.) during this period. Drought (1977-1979) resulted in significant declines that ranged from about 10 plants/ha/yr (Eremophila leucophylla) to nearly 600 plants/ha/yr (Eremophila spectabilis) while three species (Eremophila leucophylla, Maireana glomerifolia, (F. Muell. et Tate) P.G. Wilson and Ptilotus obovatus, Gaud.) either did not change or increased by only 30 to 60 plants/ha/yr during this period. Responses to kangaroo grazing were strongest during 'normal', post-drought years (1980-82) when Eragrostis xerophila, Domin. decreased by 178 plants/ha/yr on grazed areas while on protected areas there was an increase of 299 plants/ha/yr. This response was due to effects on both recruitment and, as discussed by Gardiner (1986), survival. Maireana glomerifolia, another important plant for livestock was suppressed by kangaroo grazing via reduced recruitment during the 'normal' period. Other species (Frankenia paucifora, DC. and Eremophila spectabilis) responded positively to kangaroo grazing activity during the same period.
36
Harrington, GN. "Herbivore diet in a semi-arid Eucalyptus populnea woodland. 1. Merino sheep." Australian Journal of Experimental Agriculture 26, no. 4 (1986): 413. http://dx.doi.org/10.1071/ea9860413.
Повний текст джерелаАнотація:
The diet of sheep was recorded by direct observation in a shrub-dominated Eucalyptus populnea woodland between Nyngan and Bourke, N.S.W., on 7 occasions over a 2-year period. Different nutritional opportunities were provided by the effects of rainfall on 3 contrasting grazing treatments. The sheep did not graze equally over the whole area available but foraged selectively so that they encountered unacceptable plants rarely. In particular variable spear grass (Stipa variabilis) was avoided once the inflorescence had emerged and only extreme hunger pressured sheep into foraging in dead stands of this grass.matured, sheep ate firstly increasing quantities of perennial forbs and then mulga (Acacia aneura). When these foods were depleted, sheep subsisted on dead perennial grass, tree litter and broad leaf hopbush (Dodonaea vlscosa). All other shrub species were unacceptable. The ability of sheep to forage successfully during dry periods put excessive pressure on perennial grass, causing it to die out. I suggest this has contributed to the increased frequency of shrub establishment in the poplar box woodlands since they have been used for pastoral production.
37
Armstrong, RD, KR Helyar, and EK Christie. "Vesicular-arbuscular mycorrhiza in semi-arid pastures of south-west Queensland and their effect on growth responses to phosphorus fertilizers by grasses." Australian Journal of Agricultural Research 43, no. 5 (1992): 1143. http://dx.doi.org/10.1071/ar9921143.
Повний текст джерелаАнотація:
Field and controlled environment studies were undertaken to determine the seasonal variation in vesicular-arbuscular mycorrhizal (VAM) propagules under different types of vegetation in the mulga (Acacia aneura) shrublands of south-western Queensland and how inoculation with VAM affects the growth and response to phosphorus fertilizers of several grasses common to this region. A most probable number (MPN) technique was used to estimate the number of viable VAM propagules under mulga shrubland and native pasture. There was a pronounced rise in MPN at a native pasture site from June to November, peaking at 1 propagule/g soil, before declining between November and May to non detectable concentrations. In the mulga shrubland site, MPN remained very low (less than 0.2 propagules/g soil) throughout the study. Pasture species in the field were screened for VAM infection in both winter and summer. Only three of the 14 species sampled were infected with VAM in winter (June) after a long drought. In contrast, 10 of the 14 species sampled in December possessed VAM-infected roots. A pot experiment was conducted to examine the influence of VAM inoculation on growth and the response to phosphate fertilizer of several important pasture grasses in pastures derived from mulga shrublands. The treatments comprised a factorial combination of inoculation or non-inoculation with VAM, four grass species (Aristida armata, Cenchms ciliaris cv. USA, Digitaria ammophilla, and Thyridolepis mitchelliana), and four rates of P fertilizer designed to range over very deficient to non-limiting for each species. All species except D. ammophilla produced growth responses to VAM inoculation. Though C. ciliaris and T. mitchelliana responded to VAM inoculation only in soil unamended with P fertilizer, A. amata showed growth responses across all P rates examined, suggesting some factor other than P was limiting this species. The growth response of the grasses to VAM inoculation was poorly correlated with the percentage of root infected with VAM. D. ammophilla had the highest levels of root infection (32%) despite producing no growth response to VAM. In contrast, T. mitchelliana had less than 2% of the root infected with VAM. All species had thin fibrous roots with long (0.35-0.47 mm), frequent root hairs. The differential growth responses to VAM inoculation of A. armata compared with the other grasses may provide a management strategy to control Aristida ingress into pastures established from mulga shrublands.
38
Start, A. N. "Fire responses and survival strategies of mistletoes (Loranthaceae) in an arid environment in Western Australia." Australian Journal of Botany 59, no. 6 (2011): 533. http://dx.doi.org/10.1071/bt11054.
Повний текст джерелаАнотація:
Between 1982 and 2008, data were collected on Loranthaceous mistletoes, their hosts and the fire responses of both, in and adjacent to the Pilbara, an arid region in Western Australia where hummock grasslands (dominated by Triodia sp. R.Br., Poaceae) and mulga woodlands (dominated by Acacia aneura Benth., Mimosaceae) are widespread. Hummock grasslands are fire prone and highly flammable. Mulga woodlands are less so, except in an inter-zone where Triodia in the understorey may be sufficiently dense to carry fire. The foliage (and fresh seed) of all mistletoe species was killed if scorched. Moreover, none had any means of long-term, in situ seed-storage. Three fire-survival strategies were observed across the 16 mistletoe taxa. One species (two varieties) was a resprouter. The other 14 were obligate seeders. Post-fire regeneration of those taxa depended on fresh seed being imported and deposited in suitable host canopies by birds. Twelve of them reduced fire risk by varying degrees of host specificity, favouring hosts that grew in fire-sheltered sites. However, two species had very low host specificity and grew on fire-vulnerable hosts in fire-prone hummock grasslands. Their low host specificity increased the likelihood that imported seed would be deposited on suitable hosts. Since pastoral settlement, fire regimes have changed and current regimes are eroding many mistletoe populations. None of the species occurring in the study area is threatened at bioregional or National levels. Nevertheless, the outlook is bleak for mistletoes growing in areas dominated by hummock grasslands, subregional extinction is likely and there are broader implications for biodiversity.
39
Gardiner, H. G. "DYNAMICS OF PERENNIAL PLANTS IN THE MULGA (ACACIA ANEURA F. MUELL.) ZONE OF WESTERN AUSTRALIA 11. SURVIVAL OF PERENNIAL SHRUBS AND GRASSES." Rangeland Journal 8, no. 1 (1986): 28. http://dx.doi.org/10.1071/rj9860028.
Повний текст джерелаАнотація:
Survival rates of arid-land perennial plant species were significantly related to climate, site factors, and grazing by kangaroos (Macropus rufus, Desmarest and Macropus robustus, Gould). Rainfall patterns ranging from severe drought to well above average resulted in responses in all species. All but Frankenia (Frankeniapauciflora, DC) responded to spatial and temporal site factors. Survival of wire wanderrie grass (Eragrostis xerophila, Domin) was severely reduced by grazing kangaroos, while poverty bush (Eremophila spectabilis, C.A. Gardn.) and Frankenra responded positively to kangaroo activity. Cotton bush (Ptilotus obovatus, Gaud.), ball-leaf bluebush (Marreana glomerifolia), (F. MueH et Tate) Wils. and Wilcox bush (Eremophila leucophylla, Benth.) showed no survival response to kangaroo grazing. The application of maximum likelihood procedures permitted subtle effects to be detected and several significant causal factors to be separated.
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J. Tongway, David, and John A. Ludwig. "Small-scale resource heterogeneity in semi-arid landscapes." Pacific Conservation Biology 1, no. 3 (1994): 201. http://dx.doi.org/10.1071/pc940201.
Повний текст джерелаАнотація:
Patchy distribution of plant populations is a hallmark of arid and semi-arid ecosystems. This has been attributed to the patchy distribution of scarce or limiting resources across the landscape and within the soil itself. Behind these descriptive properties are a range of processes which are the causal mechanisms of resource allocation, conservation and utilization within the landscape. Terrain-controlled mechanisms have been previously described in respect of groved mulga (Acacia aneura) communities. This paper describes a set of resource regulation mechanisms which are largely controlled by plants and plant communities and which are effective at fine scales. The actual mechanisms are inferred from field observations, and validated by looking for the net effects of defined processes acting over time. Plant-mediated resource control is inherently more sensitive to grazing pressure than terrain-controlled processes, because herbivores are able to quickly and drastically alter the density and basal cover of plants, and so change the effectiveness of the control processes. This may lead to a long-term change in system function. This paper examines the generality of these propositions in a series of contrasting landscape types, and proposes a framework by which landscape degradation can be assessed by examining the modes of basic resource regulation.
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Wright, B. R., and P. J. Clarke. "Relationships between soil temperatures and properties of fire in feathertop spinifex (Triodia schinzii (Henrard) Lazarides) sandridge desert in central Australia." Rangeland Journal 30, no. 3 (2008): 317. http://dx.doi.org/10.1071/rj07049.
Повний текст джерелаАнотація:
Soil temperatures during wildfires are known to influence seed bank and plant resprouting dynamics in arid Australian grasslands. Nevertheless, relationships between soil temperatures and factors such as fuel load, fuel type, season of burn, time-of-day and soil moisture are poorly understood. This study used small-scale experimental burns to determine the effects of these five variables on soil temperature profiles (0–4 cm) during fire in spinifex sandridge country in the Haasts Bluff Aboriginal Reserve, west of Alice Springs. Fuel load and type were found to strongly influence soil temperatures, with soils directly beneath Triodia hummocks experiencing more heating than hummock edges or between-hummock gaps, and soils beneath Triodia hummocks experiencing more heating than either mulga (Acacia aneura F.Muell. ex. Benth.) litter or Aristida holathera Domin. tussocks. Season and time-of-day also had strong effects on below-ground heating, with soil temperatures remaining elevated for longer periods during summer compared to winter burns, and day-time burns producing higher temperature maxima and longer durations of elevated soil temperatures than night burns. Soil moisture also had a strong impact on temperature profiles during fire, with high levels of soil moisture strongly reducing the soil heating during fire. These results indicate that the examined factors will strongly influence soil temperature regimes during spinifex wildfires. Hence, they are likely to affect the composition of plant assemblages in post-fire environments through their impacts on vegetative regeneration and on seed bank processes.
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Roshier, DA, and I. Barchia. "Relationships Between Sheep Production, Stocking Rate and Rainfall on Commercial Sheep Properties in Western New South Wales." Rangeland Journal 15, no. 1 (1993): 79. http://dx.doi.org/10.1071/rj9930079.
Повний текст джерелаАнотація:
Historical sheep production and rainfall data from 14 properties in semi-arid western New South Wales were analysed for relationships between wool production, lamb marking percentage, stocking rate and rainfall. Twelve of the properties were located on predominantly chenopod shrubland (Atriplex spp. and Maireana spp.) and two on mulga (Acacia aneura) land types. The relationship between wool production per head (WOOLHD, kg greasylsheep) and rainfall (RF, mmlyear) was similar on 10 of the 11 properties with wool production and rainfall data. This was so despite differences in vegetation type and average stocking rate. The generality of this relationship suggests that wool production per head is largely determined by a common, rainfall related factor operating over a wide range of management regimes. Stocking rates did not have a significant effect on wool production per head on the majority of properties. Data from the above properties were combined to generate the following generalised equation: -29.43 - WOOLHD = 7.5 lexp RF R~ =35.72 (P<0.01) Wool production per hectare was largely determined by stocking rate on most properties. No consistent relationship between lamb marking percentage and when rain fell could be found. However, rainfall in the period between joining and lamb marking was significant on six properties. It is concluded that total wool production is largely determined by stock numbers. The data suggests animal productivity is more dependent on management responses to dry periods and the rate of change in forage availability in the absence of rain.
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English, P. "Palaeodrainage at Uluru-Kata Tjuta National Park and implications for water resources." Rangeland Journal 20, no. 2 (1998): 255. http://dx.doi.org/10.1071/rj9980255.
Повний текст джерелаАнотація:
The stakeholders in the atypical rangeland area of Uluyu-Kata Tjufa National Park in the Northern Territory are the Aboriginal owners, hundreds of thousands of tourists, and vulnerable desert wildlife species. Sustainable water resources and maintenance of the integrity of the unique geological, ecological and cultural environment at Uluyu are major issues being addressed by the trustees of the Park. The Dune Plains area between Uluyu (Ayers Rock) and Kata Tjula (the Olgas) is the setting for a deep palaeovalley. The flat, dune-covered landscape of the present-day Dune Plains area provides no indication of the existence of the underlying palaeovalley. Integrated datasets including aeromagnetic and airborne gamma-ray spectrometric imagery, processed Landsat Thematic Mapper imagery, a digital elevation model, and water-bore logs, have enabled reconstruction of the Dune Plains palaeoriver valley. The datasets reveal a heterogeneous basement topography of domes and basins with 100 m of vertical relief (a buried 'mini-Kata Tjuia') at depth beneath the Dune Plains area, between the rock monoliths. The ancient valley became completely infilled with lake, river and wind-borne sediments during the Tertiary and Quaternary. Major faults traversing the basement beneath the area influenced early erosion and valley initiation. The palaeovalley was originally a closed valley which later evolved to a through-flowing river that fed Lake Amadeus to the north. The Dune Plains palaeovalley is now the setting for a compound bedrock- Cainozoic-sediment aquifer system which is the major source of water supply for the inhabitants and tourists of Uluyu-Kata Tjufa National Park. Major landscape units making up the Uluyu area include groundwater calcrete, sheetwash slopes of red earth, sandplains and dunefields, and modern ephemeral alluvial braidplains that are constrained to corridors afforded by swale networks. The sheetwash unit forms gently sloping aprons around outcrops and supports banded mulga shrubland. During rainfall, surface run-off acts as a 'sheetflow recharge mechanism'. This mechanism maximises water conservation allowing survival of the mulga groves and associated ecosystems. During major rainfall events, the sheetflow processes augment replenishment of the aquifer system at the base of the slopes. The palaeodrainage configuration and hydrodynamics of both the surface environment and the subsurface aquifer system are complex. The methodology used to reconstruct the Dune Plains palaeodrainage and associated aquifer system, and the hydrodynamic processes described for the Uluru area are applicable to widespread rangeland areas elsewhere across the continent. Keywords: Uluyu, Kata Tjula, Dune Plains, palaeovalley, palaeodrainage, hydrology, groundwater, aquifer, sheetwash, red earths, calcrete, hydrodynamics, mulga (Acacia aneura), run-off, run-on, recharge.
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Goodchild, A. V., and N. P. McMeniman. "Intake and digestibility of low quality roughages when supplemented with leguminous browse." Journal of Agricultural Science 122, no. 1 (February 1994): 151–60. http://dx.doi.org/10.1017/s0021859600065904.
Повний текст джерелаАнотація:
SUMMARYIn the first two of four experiments, sheep were fed,ad libitum, sorghum stover supplemented with graded levels of foliage of the shrub leucaena (Leucaena leucocephald) or mulga (Acacia aneura), which provided between 0 and 0·34 or between 0 and 0·43 of the dietary dry matter (DM) respectively. A second treatment (with or without urea) was superimposed in a factorial design. The effect of treatments on liveweight (LW) was explainable by their effects on voluntary intake of apparently digestible organic matter (DOMI). D0M1 was increased by mulga, largely due to an increase in the total voluntary intake of organic matter (OM). Leucaena increased DOMI by increasing the ration OM digestibility and, at low levels of inclusion, intake of the basal diet. Roughage intake was greatest when leucaena provided 0·15–0·20 of the dietary DM. Leucaena increased rumen ammonia, and whenever roughage intake was increased by urea, leucaena also increased it.In the third experiment, when diets were made isonitrogenous with urea, roughage intake was slightly greater when leucaena, rather than its ash or a mineral mixture, was supplemented. Total OM intake and DOMI were greatest when leucaena was fed.In the final experiment, sheep were fed one of ten treatments: three basal diets (two of sorghum stover and the third of native pasture hay) each supplemented with legumes (leucaena to the hay and one stover diet and cowpea straw to the second stover diet), ash of the respective legume and formaldehyde-treated casein. The tenth treatment was sorghum stover plus urea. For sorghum stover diets with leucaena-based or cowpea straw-based supplements, DOMI responded linearly to the nonurea nitrogen concentration of the diet. On the other hand, for native hay with leucaena-based supplements, the response of DOMI to non-urea N was negligible. It was noted that the native hay (predominantly Flinders grass,Iseilema vaginiflorum), contained lower concentrations of polyphenols than sorghum stover.It was concluded that browse foliage can increase the voluntary DOMI of sheep consuming low quality roughages by providing nitrogen and sometimes minerals and OM of greater digestibility. The slowly-degradable proteins in leucaena, cowpea straw or formaldehyde-treated casein are more effective with polyphenol-rich sorghum stover than with native hay of otherwise similar composition.
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Wilson, AD. "Forage utilization by sheep and kangaroos in a semi-arid woodland." Rangeland Journal 13, no. 2 (1991): 81. http://dx.doi.org/10.1071/rj9910081.
Повний текст джерелаАнотація:
The utilization of forage species by sheep and western grey kangaroos, and their contribution to the diets of those animals, were determined in a mulga (Acacia aneura) woodland in western New South Wales. Utilization was determined from measurements of forage yield, on pastures that were grazed by either sheep, sheep and kangaroos together or kangaroos, at a range of stocking rates. The sheep and kangaroos had similar preferences for the major grasses, with high utilization of species such as Monachather paradoxa and low utilization of the more fibrous species such as Eragrostis eriopoda. At times of forage abundance, annual and perennial forbs were a major component of sheep diet but a relatively minor component of kangaroo diet. Differences in species preference thus arose mainly in species that were uncommon or of seasonal occurrence. The overall diets of sheep and kangaroos were similar, with a year-round predominance of the same group of perennial grasses such as Thyridolepis mitchelliana. In the treatment where sheep and kangaroos grazed together, kangaroos had access to areas exclosed from sheep and their use of these areas increased with increase in stocking rate. Thus the exclosures received a similar grazing pressure by kangaroos alone, to that of the surrounding paddocks grazed by a mixture of sheep and kangaroos. It is concluded that there is direct competition between sheep and kangaroos for the main forage species. There are also long-term effects of high kangaroo populations on sheep production because the movement of kangaroos to rested paddocks negates any pasture management practice that requires periodic resting of pastures from grazing.
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Scanlan, J. C. "Some aspects of tree-grass dynamics in Queensland's grazing lands." Rangeland Journal 24, no. 1 (2002): 56. http://dx.doi.org/10.1071/rj02003.
Повний текст джерелаАнотація:
This review examines the interactions between grasses and trees that are relevant to Queensland's grazing lands. Soils and climate determine the potential amount of woody vegetation within an area and clearing, fire and grazing management can modify that potential. In general, the presence of non-leguminous trees reduces the potential grass production beneath their canopy and within woodland patches. Some non-native leguminous trees (e.g. Indian siris, Albizia lebbeck) enhance production of grasses beneath their canopies, whereas the widespread native leguminous trees, mulga (Acacia aneura) and brigalow (A. harpophylla) have not been reported to enhance grass production in the same way. At the patch scale, pasture production beneath woodlands with moderate to high tree basal areas is generally less than in open patches under the same soil and climatic conditions. At a landscape level, tree density, rainfall amount and distribution, and soil type modify pasture production within forest/woodland/shrubland systems. Grasses can reduce tree seedling survival but have little impact on mature woody plants, apart from providing fuel to carry a fire. Modelling studies have been used to examine some aspects of tree-grass production. Firstly, the relationship between grass production and an increasing amount of trees can vary from linear decrease, to exponential decrease to initial stimulation followed by a decrease, depending solely on the relative strengths of stimulatory and competitive effects of trees on grasses. Secondly, simulated pasture production within woodlands shows that the pasture production may be up to 50% higher in paddocks that have high variability in the distribution of those trees compared with areas where trees are uniformly distributed. This is due to the non-linear (negative exponential) relationship between pasture production and tree density that is commonly observed within Queensland. Lastly, simulation studies show that total aboveground production (trees and pasture) of mulga woodland increases as the number of trees per hectare increases. The pasture production response to tree clearing or tree planting depends on tree species, rainfall, soil type, climatic history and post-clearing management including fire and grazing, and will change with time since clearing. The greatest relative increase in pasture production following the removal of woody vegetation occurs: when the initial tree basal area is highest; where rainfall is evenly distributed though the year and on fertile soils with a low water holding capacity.
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Pegler, Lachlan, Renée Moore, and Delphine Bentley. "Bore drain replacement in south-west Queensland: benefits and costs for land managers." Rangeland Journal 24, no. 2 (2002): 185. http://dx.doi.org/10.1071/rj02010.
Повний текст джерелаАнотація:
The Bore Drain Replacement Project (BDRP) in south-west Queensland provided government subsidies to land managers to convert water distribution systems from open earth bore drains to piped water systems, thereby addressing Great Artesian Basin (GAB) sustainability issues. To fully evaluate the benefits and costs of the project for land managers, both a financial benefit-cost analysis and a study of land managers' perceptions were conducted. The main benefit for land managers from bore drain replacement, was a substantial decrease in operating costs (mean decrease of 87%). Results of the financial benefit-cost analysis showed that the mean private benefit to total cost ratio (BP:CT) (0.86, at a real discount rate of 6%, over 10 years) was less than the break-even value of unity . The mean BP:CT (0.6) for land managers with less than 50% of bore drains on mulga (Acacia aneura F. Muell ex. Benth) land systems was also less than unity, while those land managers with bore drains predominately on mulga land systems had a mean BP:CT that only marginally exceeded unity (1.1). With a government subsidy (study mean 72%), the private benefits to private cost ratio (BP:CP), averaged across all land managers in the study, was 2.25. The break-even subsidy level for land managers was calculated as 17% of the total capital cost. Land managers perceived a number of important benefits from bore drain replacement that were not included in the financial benefit-cost analysis, due to difficulty quantifying values. These included benefits from changes in grazing management, increased time-savings and an improved quality of life. In general, there were no changes documented in animal productivity, native and feral animal populations, or carrying capacity in the 18 months since piping, although potential changes for the future were identified. Some land managers noted improvements to natural resource condition near bore drains after closure, while most expected little deterioration in natural resource condition near the new water points. Recommendations are made for ongoing funding support for bore drain replacement, including further monitoring and evaluation, with emphasis on conducting an economic public and private benefit-cost analysis. Land managers' capacity to pay, willingness to adopt change and public benefits of the project should be considered in cost sharing arrangements and determination of future government subsidy levels.
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Wright, Boyd R., Donald C. Franklin, and Roderick J. Fensham. "The ecology, evolution and management of mast reproduction in Australian plants." Australian Journal of Botany 70, no. 8 (December 20, 2022): 509–30. http://dx.doi.org/10.1071/bt22043.
Повний текст джерелаАнотація:
Australia is home to a diverse assemblage of plant species that display marked population-level variation in inter-annual flower or seed output (i.e. masting). These include a semelparous bamboo with an estimated inter-crop period of 40–50 years, numerous iteroparous masting gymnosperms, angiosperms that include landscape-dominant eucalypts, arid-zone wattles and spinifex (Triodia spp.) grasses, and a rich selection of species that display disturbance-related forms of masting such as pyrogenic flowering and environmental prediction. Despite the prevalence of masting in the Australian flora, there has been a paucity of research on these plants. Nevertheless, from the literature available, it appears that, similar to other parts of the world, a continuum of inter-year reproductive variability exists, with a small number of species displaying extreme–high inter-annual seeding variability. From experimental studies and many anecdotal reports, most of the fitness benefits associated with masting evident overseas also operate in Australia (e.g. predator satiation, improved pollination efficiency, and environmental prediction). Additionally, some Australian masting species offer periodically important food resources for Aboriginal nations in the form of seed or fruit. These include the bunya pine (Araucaria bidwillii), members of the cycad genera Cycas and Macrozamia, spinifex (Triodia) grasses, and mulga shrubs (Acacia aneura). Key future research areas for effective conservation of Australian masting plants include (1) improved understanding of how management interventions such as burning and silvicultural thinning influence regeneration dynamics and higher-order trophic interactions, (2) further longitudinal monitoring across a range of habitats to identify other, as yet unknown, species that display reproductive intermittency, and (3) elucidation of how changes to temperature, precipitation and fire regimes under climate change will affect reproduction and regeneration dynamics of the Australian masting flora.
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Freudenberger, D., A. Wilson, and R. Palmer. "The Effects of Perennial Grasses, Stocking Rate and Rainfall on Sheep Production in a Semi-Arid Woodland of Eastern Australia." Rangeland Journal 21, no. 2 (1999): 199. http://dx.doi.org/10.1071/rj9990199.
Повний текст джерелаАнотація:
A grazing study was conducted in a semi-arid mulga (Acacia aneura) woodland to determine the relative importance of variables controlling sheep production in this environment. The study was based on six sheep stocking rates (0.3-0.8 sheeplha) with the exclusion of other large herbivores including kangaroos and feral goats. The availability of forage and its components, together with the wool growth and live weight of the sheep were measured every three months for seven years from October 1986. Annual rainfall accounted for 60% of the annual variation in live weight gain per head and 79% of the variation in wool growth per head. Stocking rate accounted for an additional 10% of the variation. Rainfall accounted for this large proportion of variation by its strong influence on the yield of green leaf which accounted for 78% of the variation in live weight gain and 66% of the variation in wool growth. Green leaf was a determinant of sheep production because of its superior crude protein content and digestibility compared to dry leaf and stem. The species comprising this green leaf had an influence on sheep production only during drier years when the presence of palatable perennial grasses became important to sheep production. The frequency and yield of perennial grasses were greatly diminished at high stocking rates. This change in forage composition caused a decline in sheep productivity as detected by a loss of linearity in the relationship between stocking rate and live weight gainlhead. We conclude that adjusting stocking rates is required in this environment for maintenance of long-term sheep productivity and landscape function. The loss of palatable perennial C, grasses over much of the region has reduced livestock productivity and increased the variability in forage availability. Stock numbers should be adjusted at critical times to avoid losing perennial grasses that are important for sheep production in drier years. New grazing strategies are required to restore these grasses to the region.
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Pressland, AJ, and DC Cowan. "Response of plant growth to removal of surface soil of the rangelands of western Queensland." Rangeland Journal 9, no. 2 (1987): 74. http://dx.doi.org/10.1071/rj9870074.
Повний текст джерелаАнотація:
Pot and field studies were conducted to determine the potential effect on plant production of soil erosion in western Queensland. Soil from both the Mitchell grass (Astrebla spp.) and mulga (Acacin aneura) woodlands were used, but the studies concentrated on the latter soils. Test plants (oats, sorghum and pasture grass species) were grown in soil taken from sequential 5 cm intervals from the surface to 20 cm down the profile of each of the selected soils. Plants growing in subsurface soil, irrespective of soil type or history, were less productive than those growing on surface soil. This was attributed in part to reduced soil fertility and a difference in soil pH. Buffel grass (Cenchrur ciliaris), a species which has some use as an improved pasture in these rangelands, would be seriously disadvantaged on eroded soils. It is concluded that erosion of surface soil on these landscapes should be minimized by conserving ground cover.