Grazing pressure impacts on two Aristida/Bothriochloa native pasture communities of central Queensland

2017 ◽  
Vol 39 (3) ◽  
pp. 227 ◽  
Author(s):  
Trevor J. Hall ◽  
Paul Jones ◽  
Richard G. Silcock ◽  
Piet G. Filet
Keyword(s):  
Ground Cover ◽  
Predictive Modelling ◽  
Grazing Pressure ◽  
Total Contribution ◽  
Themeda Triandra ◽  
Crown Cover ◽  
Economic Production ◽  
Eastern Australia ◽  
Negative Effect ◽  
Native Pastures

Managing native pastures for sustainable and economic production requires a good understanding of grazing effects on pasture dynamics. The Aristida/Bothriochloa pastures of north-eastern Australia are important for cattle production but little data on grazing pressure impacts on pastures are available to guide management decisions of producers, for land management education programs, or for predictive modelling. To address this deficiency, four different continuous grazing intensities were imposed on woodland communities over 7 or 8 years at two sites: a Eucalyptus populnea (poplar box) and a E. melanophloia (silver-leaved ironbark) community. Both sites had replicated paddocks grazed at a low, medium or high grazing pressure by +/− tree killing using herbicide (12 paddocks), and 12 ungrazed (nil grazing pressure) 1-ha plots subjected to the same tree-killing contrasts. Grazed paddock areas were fixed and varied between 3.5 and 21.5 ha. Differential grazing pressures were reset each autumn, by adjusting cattle numbers to consume over the next year the equivalent of 0%, 25%, 50% or 75% of the standing pasture mass available. Pasture grasses suitable as indicators of grazing pressure were identified for both communities. Under low grazing pressure, Themeda triandra (kangaroo grass) was the only desirable grass to show a significant increase in total contribution over time at both sites, although Dichanthium sericeum (Queensland bluegrass) also increased its contribution at the poplar box site. Chloris species increased their contribution as grazing pressure increased. The proportion of less palatable Aristida spp. (wiregrasses) in the pasture was not affected by high grazing pressure, although they increased at low grazing pressure in the poplar box community. There were no consistent changes in native legumes or weedy forb species to any treatment. Increasing grazing pressure had a greater negative effect on pasture mass, ground cover and pasture crown cover area than on changing species composition. Most changes in composition due to grazing pressure were smaller than those associated with variable seasonal rainfall, and were greater in the poplar box community. In above-average rainfall years grazing up to 50% of autumn standing pasture mass had no detrimental effect on composition in treeless poplar box country in the short term. The pastures remained stable or improved in both communities when grazing pressure was set annually to utilise 25% of the standing autumn forage.

Effects of grazing management on botanical composition of native grass-based pastures in temperate south-east Australia

2000 ◽  
Vol 40 (2) ◽  
pp. 225 ◽  
Author(s):  
D. L. Garden ◽  
G. M. Lodge ◽  
D. A. Friend ◽  
P. M. Dowling ◽  
B. A. Orchard
Keyword(s):  
Management Strategies ◽  
Grazing Pressure ◽  
Grazing Management ◽  
Botanical Composition ◽  
Holcus Lanatus ◽  
Themeda Triandra ◽  
Continuous Grazing ◽  
Wide Range ◽  
Drought Conditions ◽  
Native Pastures

Grazing management strategies to alter botanical composition of native pastures were investigated at 4 locations in the high rainfall zone of south-east Australia, including Tasmania. These studies were conducted as part of the Temperate Pasture Sustainability Key Program, which evaluated the effects of grazing management on a wide range of pasture types between 1993 and 1996. Pastures in this study were based on Aristida ramosa/Bothriochloa macra, Microlaena stipoides–Austrodanthonia spp. or Themeda triandra–Austrodanthonia spp. Seasonal rests, increased grazing pressure in spring, mob stocking and cutting for hay were compared to continuous grazing at all sites. In addition, specific local treatments were tested at individual sites. Changes in composition resulting from the treatments were minimal at most sites. This may have been due to a combination of the inherent stability of the pastures, the relatively short duration of the experiments, and the drought conditions experienced, which minimised differences between treatments. Some strategies to alter composition of natural pastures are suggested. In the Aristida–Bothriochloa pasture there was a general decrease in Aristida and an increase in Bothriochloa, which was largely unaffected by the type of grazing management applied. The combination of drought conditions and increasing grazing pressure was sufficient to alter composition without specific management strategies being necessary. In the Themeda–Austrodanthonia pasture, resting in spring, 12-month rests or cutting for hay (which involved a spring rest) allowed Themeda to increase in the pasture. The Microlaena–Austrodanthonia pastures were very stable, especially where annual grass content was low. However, certain treatments allowed Microlaena to increase, a result which is regarded as being favourable. The major effects in these latter pastures were on undesirable species. Vulpia spp. were reduced by resting in autumn and increased spring grazing pressure, while Holcus lanatus was increased dramatically by resting in spring and was also increased by resting in autumn or winter, but only when conditions were suitable for growth of this species. In many cases, treatment differences were only expressed following recovery from drought, showing that timing of grazing management to achieve change is critical.

Soil and plant relationships with cattle production on a property scale in the monsoonal tallgrass tropics.

1988 ◽  
Vol 10 (1) ◽  
pp. 18 ◽  
Author(s):  
TH McCosker ◽  
PK O'Rourke ◽  
AR Eggington ◽  
FW Doyle
Keyword(s):  
Pregnancy Rate ◽  
Average Daily Gain ◽  
Previous History ◽  
Grazing Pressure ◽  
Soil Types ◽  
Cattle Production ◽  
Protein Nitrogen ◽  
Themeda Triandra ◽  
Wide Range ◽  
Native Pastures

Extreme variability in cattle production between replicate paddocks in a large supplementation experiment on Mount Bundey Station in the Danvin pastoral district of the Northern Territory, led to a search for reasons for the differences. Soil type, land unit and pasture parameters were related to cattle production parameters. Pregnancy rates of lactating heifers were positively related to yields of Themeda triandra, Sorghum plumosum, Eriachne burkittii and Eragrostis spp., the fist three of which declined in yield following heavy grazing pressure. Quantity of pasture was more closely correlated with animal production than was quality due to the wide range in yields and narrow range in quality attributes. Pregnancy rate in lactating heifers was more sensitive to yield of pasture species than was lactating cow pregnancy rate, breeder mortality, calf weight per breeder mated or steer average daily gain. Heifers consumed less supplement relative to their requirements than mature cows and steers and their response was not confounded by previous history. These factors probably account for their greater sensitivity to pasture variations. Pregnancy rate of cows was positively related to the proportion of lowland soil types and negatively to proportion of lithosol (hills). An equation incorporating the percentages of these soils, explained 63%. 42% and 39% of the variation in lactating cow pregnancy rate in 1982, 1983 and 1984 respectively. Variation in pregnancy rate among paddocks was therefore largely attributed to variation in the proportions of "upland" and "lowland" soil types. Sensitivity to grazing pressure of species within the native pasture was indicated by localized damage to T. triandra and S. plumosum and a large reduction in yield of Sintrans after five years of continuous grazing with access to non-protein nitrogen supplements at one breeder to 14ha. Native pastures in the Adelaide River area would not sustain this stocking rate. 18

scholarly journals Restoration of eucalypt grassy woodland: effects of experimental interventions on ground-layer vegetation

2014 ◽  
Vol 62 (7) ◽  
pp. 570 ◽  
Author(s):  
S. McIntyre ◽  
R. B. Cunningham ◽  
C. F. Donnelly ◽  
A. D. Manning
Keyword(s):  
Coarse Woody Debris ◽  
Native Species ◽  
Woody Debris ◽  
Ground Cover ◽  
Grazing Pressure ◽  
Livestock Grazing ◽  
Ground Layer ◽  
Total Biomass ◽  
Eastern Australia ◽  
Main Driver

We report on the effects of broad-scale restoration treatments on the ground layer of eucalypt grassy woodland in south-eastern Australia. The experiment was conducted in two conservation reserves from which livestock grazing had previously been removed. Changes in biomass, species diversity, ground-cover attributes and life-form were analysed over a 4-year period in relation to the following experimental interventions: (1) reduced kangaroo density, (2) addition of coarse woody debris and (3) fire (a single burn). Reducing kangaroo density doubled total biomass in one reserve, but no effects on exotic biomass, species counts or ground cover attributes were observed. Coarse woody debris also promoted biomass, particularly exotic annual forbs, as well as plant diversity in one of the reserves. The single burn reduced biomass, but changed little else. Overall, we found the main driver of change to be the favourable growth seasons that had followed a period of drought. This resulted in biomass increasing by 67%, (mostly owing to the growth of perennial native grasses), whereas overall native species counts increased by 18%, and exotic species declined by 20% over the 4-year observation period. Strategic management of grazing pressure, use of fire where biomass has accumulated and placement of coarse woody debris in areas of persistent erosion will contribute to improvements in soil and vegetation condition, and gains in biodiversity, in the future.

scholarly journals The importance of travelling stock reserves for maintaining high-quality threatened temperate woodlands

2017 ◽  
Vol 65 (7) ◽  
pp. 507 ◽  
Author(s):  
Thea O'Loughlin ◽  
Luke S. O'Loughlin ◽  
Damian R. Michael ◽  
Jeffrey T. Wood ◽  
Helen P. Waudby ◽  
...  
Keyword(s):  
Plant Species ◽  
Land Tenure ◽  
Agricultural Production ◽  
Ground Cover ◽  
Grazing Pressure ◽  
Agricultural Landscapes ◽  
Permanent Plots ◽  
Private Land ◽  
Native Plant ◽  
Eastern Australia

Travelling stock reserves (TSRs) are thought to represent some of the highest-quality and least degraded remnants of threatened temperate woodland in south-eastern Australia. These public reserves have not had the same high levels of grazing pressure and other disturbances as woodland remnants on private land. Thus, TSRs are expected to be important for the protection of biodiversity in heavily cleared and modified landscapes. We tested the hypothesis that land tenure had significant effects on the quality of woodlands by comparing vegetation structural attributes between TSRs and remnant vegetation used for primary production purposes. Vegetation attributes were monitored in 155 permanent plots over 5 years in remnant temperate woodland sites in the Riverina bioregion of New South Wales. Overall, TSRs supported higher native plant species richness and were characterised by higher ground cover of native shrubs and less cover of exotic plant species than agricultural production areas. We found land tenure had significant effects on some vegetation attributes demonstrated to be important for threatened fauna. We attribute these results to TSRs having a history of lower grazing pressure compared with remnants managed for agricultural production. Our study provides empirical evidence to support the high conservation value of TSRs in formerly woodland-dominated, but now extensively cleared agricultural landscapes.

A Multivariate Growth-form Analysis of Grassland and Forest Forbs in South-eastern Australia

1997 ◽  
Vol 45 (4) ◽  
pp. 691 ◽  
Author(s):  
Ian D. Lunt
Keyword(s):  
Growth Form ◽  
Ground Cover ◽  
Themeda Triandra ◽  
Form Analysis ◽  
Relative Paucity ◽  
Native Grasslands ◽  
Forest Sites ◽  
Eastern Australia ◽  
Forest Remnants ◽  
Species Groups

The growth-form composition of grazed and unburnt, grassy forest remnants and ungrazed, frequently burnt, anthropogenic native grasslands in Gippsland, Victoria were compared, using a multivariate, clustering analysis of the growth-form and life-form attributes of 53 forb species. Groups comprising (1) annual forbs, (2) clambering, repent and decumbent perennials, and (3) rosette perennials and rhizomic ground-cover forbs occurred in significantly more forest than grassland quadrats. One group, mostly containing tall erect geophytes with linear basal leaves, occurred in significantly more grassland than forest quadrats. Grassland quadrats contained significantly more tall forbs (> 20 cm) than forest quadrats, whilst forest quadrats contained significantly more forbs of short to medium height (< 20 cm). There was a significant, positive correlation between plant height and frequency of occurrence in grassland quadrats (rs = 0.58, P < 0.001), and a significant, although weak, negative correlation in forest quadrats (rs = -0.29, P < 0.05). Short forbs are likely to have been depleted from grassland sites owing to competition from the dominant tussock grass, Themeda triandra Forsskal. By contrast, ground cover in forest sites is of relatively low stature, biomass and cover, allowing short forbs to persist. The relative paucity of tall forbs from forest remnants is suspected to be at least partly due to intensive stock grazing in the past.

Studies of competition between Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock) and native pastures. 2. Seedling responses

2008 ◽  
Vol 59 (3) ◽  
pp. 237 ◽  
Author(s):  
W. B. Badgery ◽  
D. R. Kemp ◽  
D. L. Michalk ◽  
W. McG. King
Keyword(s):  
Dry Matter ◽  
Seedling Recruitment ◽  
Perennial Grass ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Native Grass ◽  
Eastern Australia ◽  
Native Pastures ◽  
Grass Weed ◽  
Native Perennial Grass

Native perennial grass competition can substantially reduce the invasion of Nassella trichotoma (serrated tussock), a major perennial grass weed problem in south-eastern Australia. This paper reports on a field experiment that investigated the recruitment of N. trichotoma seedlings, and determined what level of native grass competition was needed to prevent establishment in the central-west of NSW. Grasslands that maintained >2 t dry matter (DM)/ha and 100% ground cover (measured in spring) prevented N. trichotoma seedling recruitment. Relatively small amounts of perennial grass (>0.5 t DM/ha measured in spring) resulted in mortality of N. trichotoma seedlings that had recruited earlier in the year, through the next summer. Flupropanate also markedly reduced native perennial grasses and substantially increased N. trichotoma seedling establishment 12 months after application. Rotational grazing to maintain adequate levels of DM was an important management tactic that prevented N. trichotoma establishment and survival.

Grazing pressure and tree competition affect cattle performance and native pastures in Eucalypt woodlands of Queensland, north-eastern Australia

2020 ◽  
Vol 60 (7) ◽  
pp. 953
Author(s):  
Trevor J. Hall ◽  
Richard G. Silcock ◽  
David G. Mayer
Keyword(s):  
Body Condition ◽  
High Pressures ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Pasture Production ◽  
Eastern Australia ◽  
North Eastern ◽  
Eucalypt Woodlands ◽  
Native Pastures ◽  
Grazing Pressures

Context Well managed grazing pressure will optimise animal and pasture production, and preserve the soil to maintain a viable beef business on native pastures in eucalypt woodlands. Aims A cattle grazing experiment was established to measure animal and pasture performance under management practices used in the Aristida/Bothriochloa native pastures in central Queensland. Methods Performance of Brahman-cross steers and pastures were measured in an experiment with three grazing pressures by two tree densities in a Eucalyptus populnea woodland in north-eastern Australia over 8 years in paddocks of 4–18 ha. Key results At low grazing pressure with trees killed by herbicide (‘cleared’), stocking rate increased 35% as pasture composition and biomass improved over 8 years. At low grazing pressure where treed, stocking rate remained constant, however, at high grazing pressure where treed, it was reduced after 4 years. The annual liveweight gain increased from 0.37 to 0.45 to 0.51 kg/head.day as grazing pressure was reduced from high to medium to low grazing pressure respectively, and across grazing pressures it decreased from 0.49 where cleared to 0.39 kg/head.day where treed. Liveweight gain per hectare increased under low grazing pressure and declined at medium and high pressures. Body condition scores responded positively to lower grazing pressure and a lack of tree competition to pastures. This treatment combination also produced higher animal sale values. Pasture biomass, basal area and ground cover were all affected negatively by increasing grazing pressure. Conclusions Grazing 25% of autumn pasture improved dry matter production, species composition and land condition, and increased steer growth rates, body condition and their market value. This grazing pressure produced an increasing trend in stocking rates relative to the decline at higher grazing pressures. Higher liveweight gain/ha was produced initially at high grazing pressure (75% utilisation), however, after 4 years animal condition and pastures deteriorated, requiring a reduction in stocking rate to maintain the condition of both the remaining animals and the pastures. Managing tree competition to pastures is necessary to maintain the higher animal production potential. Implications This objective information demonstrates the benefits for cattle, pastures and long-term economic outcomes of managing for conservative grazing pressure and controlling tree competition to pasture in this woodland. Applying these findings can improve beef business outcomes and provide management groups with objective educational resources.

Can bare ground cover server as a surrogate for plant biodiversity in grazed tropical woodlands?

2009 ◽  
Vol 31 (1) ◽  
pp. 103 ◽  
Author(s):  
Juliana McCosker ◽  
John Rolfe ◽  
Rod Fensham
Keyword(s):  
Ground Cover ◽  
Plant Species Richness ◽  
Perennial Grasses ◽  
Individual Species ◽  
Bare Ground ◽  
Themeda Triandra ◽  
Land Type ◽  
Eastern Australia ◽  
High Level ◽  
Tropical Woodlands

A bare ground index derived by remote sensing would provide a rapid methodology for assessing the biodiversity condition of an ecosystem, providing that ground cover is a satisfactory correlate with key biodiversity attributes. The relationship between plant species richness and the abundance of individual species was examined in relation to ground cover within silver-leaved ironbark (Eucalyptus melanophloia F. Muell.) woodlands in the Desert Uplands bioregion of north-eastern Australia. There was significant correlation between the bare ground index and ground cover and biomass measurements. Twenty-four species, including the perennial grasses Sehima nervosum (Rottler) Stapf, Themeda triandra Forssk. and Bothriocloa ewartiana (Domin) C.E. Hubb., were significantly and negatively correlated with bare ground. Scleroleana birchii (F. Muell.) Domin and Sida fibulifera Lindl.displayed significant positive relationships with increasing bare ground, and where abundant indicate heavy grazing in this land type. The study suggests that satellite-derived data does provide a meaningful methodology for assessing vegetation condition although it is strongly associated with seasonal conditions, but is only useful in relation to the regional average for a land type. The findings suggest that plant diversity is maintained at a relatively high level throughout most of these woodlands in the Desert Uplands.

Soil temperatures and seed burial in relation to the performance of Heteropogon contortus and Themeda australis in burnt native woodland pastures in Eastern Queensland

1969 ◽  
Vol 17 (2) ◽  
pp. 269 ◽  
Author(s):  
JC Tothill
Keyword(s):  
Ground Cover ◽  
Ground Level ◽  
Maximum Temperature ◽  
Seed Burial ◽  
Ambient Temperatures ◽  
Seasonally Dry ◽  
Heteropogon Contortus ◽  
Average Maximum ◽  
Soil Temperatures ◽  
Native Pastures

The factors underlying the increasing dominance of Heteropogon contortus (bunch or black spear grass) as a result of regularly burning native pastures in eastern Queensland have been investigated. In the subtropical environment of this experiment the removal of ground cover by burning or other means significantly increased the average maximum temperature of the surface soil. Burning favoured the germination of buried H. contortus seed at a time when ambient temperatures were too low for this to occur in unburnt situations. In late seasons and in the seasonally dry tropics insufficient soil moisture would tend to limit growth and germination until ambient temperatures are high, in which case the burning effect would be less pronounced. The efficient seed burial mechanism of H. contortus places it at an establishment advantage over other commonly associated species such as blue grasses (Bothriochloa, Dichanthium) and others whose seeds remain largely in the surface litter. Fire destroys much of this litter, the microhabitat for seed germination at ground level, and some of the weaker perennial plants. The implications of these results in relation to the increased dominance of either H. contortus or Themeda australis (kangaroo grass) are discussed.

Spring fire effects on two Aristida/Bothriochloa native pastures in central Queensland, Australia

2018 ◽  
Vol 40 (5) ◽  
pp. 485
Author(s):  
R. G. Silcock ◽  
T. J. Hall ◽  
P. Jones ◽  
P. G. Filet ◽  
J. Douglas
Keyword(s):  
Prescribed Burning ◽  
Woody Plant ◽  
Marked Change ◽  
Ground Cover ◽  
Weather Conditions ◽  
Fire Effects ◽  
Heteropogon Contortus ◽  
Eucalypt Woodlands ◽  
Native Pastures ◽  
The Many

Controlled burns are commonly used to suppress woody plant regrowth and to remove accumulated unpalatable pasture from rangelands and occasionally to alter pasture composition in native pastures in central Queensland, Australia. Outcomes can be somewhat unpredictable and short-term, and reliable evidence is needed to confirm the likely long-term efficacy of such fires. We imposed a regime of repeated spring burns on native Aristida/Bothriochloa pastures growing in two contrasting eucalypt woodlands of central Queensland to determine the effects on pasture composition, ground cover, landscape stability and woody plant recruitment, all in the absence of grazing. The sites selected were a silver-leaved ironbark (Eucalyptus melanophloia F.Muell.) woodland and a poplar box (E. populnea F.Muell.) woodland. Weather conditions precluded spring burns in 3 years out of 7 at the silver-leaved ironbark site and in 2 years out of 8 at the poplar box site. The burn intensity was variable, and frequent fires produced a marked change in abundance of only a few pasture species. Depending on the site, fires significantly increased the frequency of Enneapogon spp., Bothriochloa bladhii (Retz.) S.T.Blake and Dichanthium sericeum (R.Br.) A.Camus and reduced the frequency of some minor components such as Cymbopogon spp., Panicum effusum R.Br., Cenchrus ciliaris L. and, ephemerally, that of some forbs. Contrary to expectation, only Aristida calycina R.Br. declined in abundance among the many Aristida species present, and the abundance of Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. barely increased under regular spring fires. The total germinable seeds of herbaceous species in the soil each spring was significantly reduced by burning in the previous spring. Repeated spring fires rarely reinforced any initial change induced by burning, and slightly lowered average ground cover as well as various indices of landscape stability and ecosystem functionality. Changes produced were not always consistent across the two communities. Though prescribed burning is often important for maintaining grazing productivity and landscape values, very regular use is not recommended.

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