Floristic composition and pasture condition of Aristida/Bothriochloa pastures in central Queensland. II. Soil and pasture condition interactions

2015 ◽  
Vol 37 (2) ◽  
pp. 217
Author(s):  
R. G. Silcock ◽  
T. J. Hall ◽  
P. G. Filet ◽  
A. M. Kelly ◽  
D. Osten ◽  
...  
Keyword(s):  
Soil Type ◽  
Plant Density ◽  
Surface Condition ◽  
Good Condition ◽  
Basal Area ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Tree Cover ◽  
Themeda Triandra ◽  
Heteropogon Contortus

Sustainable management of native pastures requires an understanding of what the bounds of pasture composition, cover and soil surface condition are for healthy pastoral landscapes to persist. A survey of 107 Aristida/Bothriochloa pasture sites in inland central Queensland was conducted. The sites were chosen for their current diversity of tree cover, apparent pasture condition and soil type to assist in setting more objective bounds on condition ‘states’ in such pastures. Assessors’ estimates of pasture condition were strongly correlated with herbage mass (r = 0.57) and projected ground cover (r = 0. 58), and moderately correlated with pasture crown cover (r = 0.35) and tree basal area (r = 0.32). Pasture condition was not correlated with pasture plant density or the frequency of simple guilds of pasture species. The soil type of Aristida/Bothriochloa pasture communities was generally hard-setting, low in cryptogam cover but moderately covered with litter and projected ground cover (30–50%). There was no correlation between projected ground cover of pasture and estimated ground-level cover of plant crowns. Tree basal area was correlated with broad categories of soil type, probably because greater tree clearing has occurred on the more fertile, heavy-textured clay soils. Of the main perennial grasses, some showed strong soil preferences, for example Tripogon loliiformis for hard-setting soils and Dichanthium sericeum for clays. Common species, such as Chrysopogon fallax and Heteropogon contortus, had no strong soil preference. Wiregrasses (Aristida spp.) tended to be uncommon at both ends of the estimated pasture condition scale whereas H. contortus was far more common in pastures in good condition. Sedges (Cyperaceae) were common on all soil types and for all pasture condition ratings. Plants identified as increaser species were Tragus australianus, daisies (Asteraceae) and potentially toxic herbaceous legumes such as Indigofera spp. and Crotalaria spp. Pasture condition could not be reliably predicted based on the abundance of a single species or taxon but there may be scope for using integrated data for four to five ecologically contrasting plants such as Themeda triandra with daisies, T. loliiformis and flannel weeds (Malvaceae).

Grazing management of natureal pastures at Trangie, NSW

1956 ◽  
Vol 7 (4) ◽  
pp. 233 ◽  
Author(s):  
EF Biddiscombe ◽  
RJ Hutchings ◽  
G Edgar ◽  
EG Cuthbertson
Keyword(s):  
Body Weight ◽  
Plant Density ◽  
Basal Area ◽  
Body Weight Loss ◽  
Perennial Grasses ◽  
Growth Stages ◽  
Natural Pasture ◽  
Continuous Grazing ◽  
Average Rainfall ◽  
Fleece Weight

Results of a 5-year grazing experiment on Stipa-Chlaris natural pasture are presented. Treatments were three rates of stocking each tested with continuous grazing, autumn deferment, and spring deferment. These were studied in relation to: (a) body weight and wool production of Merino wethers; (b) available feed; (c) density and basal area of the perennial grasses. Lighter stocking (one sheep/2 ac) showed little superiority in production per animal under the generally favourable rainfall conditions. There was only one interval of acute feed shortage in which heavier stocking (one sheep/ac) caused extreme body-weight loss and lower fleece weight. The spelling treatments gave no advantage over continuous grazing, either to sheep or to pasture. Effect of stocking rate on perennial grasses mainly depended upon the amount of rainfall received during certain growth stages of the species, e.g. the winter vegetative growth of Stipa, and the March-April maturation of Chloris and Digitaria. Generally, lighter stocking was favourable to plant density and basal area in seasons of average or below average rainfall; heavier stocking was best in wet seasons. Probable reasons for these relationships are discussed.

Grazing Modifies Woody and Herbaceous Components of North Queensland Woodlands.

1996 ◽  
Vol 18 (1) ◽  
pp. 47 ◽  
Author(s):  
JC Scanlan ◽  
AJ Pressland ◽  
DJ Myles
Keyword(s):  
Dry Matter ◽  
Woody Plant ◽  
Plant Density ◽  
Ground Cover ◽  
Growth Conditions ◽  
Drought Period ◽  
Percentage Contribution ◽  
Heteropogon Contortus ◽  
Average Rainfall ◽  
Tussock Grasses

Grazed and exclosed areas within north Queensland woodlands were studied over a six-year period which included a drought followed by an above average rainfall period. Despite drought conditions, woody plant density increased, with exclosed areas showing a greater increase than grazed areas. During the drought period, a pattern of herbaceous vegetation strips interspersed with bare areas developed. Standing dry matter and ground cover increased rapidly in response to above average rainfall following the drought. Also, the pattern of strips became less apparent during the more favourable growth conditions. The percentage contribution of native tussock grasses (principally Heteropogon contortus) to total pasture dry matter varied to a greater extent over the six-year period than the naturalised stoloniferous Bothriochloa pertusa.

Establishment and development of surface sown pasture species in a nitrophilous weed association: effect of herbicide rate

1981 ◽  
Vol 21 (112) ◽  
pp. 531 ◽  
Author(s):  
MH Campbell ◽  
AR Gilmour ◽  
DT Vere
Keyword(s):  
Festuca Arundinacea ◽  
New South ◽  
Basal Area ◽  
Ground Cover ◽  
Weed Suppression ◽  
Perennial Grasses ◽  
Herbicide Treatment ◽  
South Wales ◽  
Annual Grasses ◽  
Association Effect

In an experiment carried out between 1976 and 1979 near Orange, New South Wales, the effects of four rates of glyphosate (0.1 25, 0.25, 0.5 and 1.0 kg/ha active ingredient (a.i.)) and three rates of amitrole (0.5, 0.75, 1.0 kg/ha a.i. in association with 2.5 kg/ha a.i. 2,2-DPA) on the suppression of a nitrophilous weed association (broadleafed plants, annual grasses, native perennial grasses, annual legumes) and the resultant establishment and development of surface sown pastures species (Medicago sativa, Phalaris aquatica, Dactylis glomerata, Festuca arundinacea) were measured. The length of weed suppression in the year of spraying (1976) was the most important factor in the eventual development of the sown species. Glyphosate at 1.0 kg/ha a.i. gave better weed suppression for longer (up to and beyond 23 weeks after spraying) than any other herbicide treatment and allowed sown species to establish and survive the first summer better and thus produce a better pasture three years later. Weed suppression between 8 and 19 weeks after spraying affected the initial establishment of sown species; in general, establishment was better on herbicide treatments that reduced ground cover of the weed association to less than 30% in this period. Rate of weed suppression had no effect because no sown species germinated in the eight weeks after spraying. Three years after treatment the ground cover of the nitrophilous weed association was 31% on the best herbicide treatment (glyphosate, 1.0 kg/ha a.i.) and 83% on the unsprayed control; the respective ground cover of sown species was 60% and 7%. The increase in ground cover of sown species during the three years was on most treatments almost entirely due to the increase in basal area of P. aquatica.

Effects of nitrogen and phosphorus on vegetation dynamics of a degraded native grassland in semi-arid south-eastern Australia

2011 ◽  
Vol 33 (1) ◽  
pp. 87 ◽  
Author(s):  
R. B. Hacker ◽  
I. D. Toole ◽  
G. J. Melville
Keyword(s):  
Vegetation Dynamics ◽  
Plant Density ◽  
Perennial Grass ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Nitrogen And Phosphorus ◽  
Mineral N ◽  
Eastern Australia ◽  
Semi Arid

The roles of nitrogen (N) and phosphorus (P) in controlling vegetation transitions in a degraded semi-arid grassland were investigated in a factorial experiment that combined two initial levels of perennial plant density (low and high), three levels of N (N+, N0 and N–) and two levels of P (P+ and P0). Increased levels of both N and P were achieved by fertiliser addition while sucrose was used to reduce the level of N. Vegetation dynamics were driven primarily by soil N rather than P. Addition of sucrose, which was inferred to result in the immobilisation of mineral N, reduced the growth of annual species and facilitated the establishment and growth of native perennial grasses. Addition of P generally had no significant effect on dry matter production, either in total or for species grouped as forbs, annual grasses and perennial grasses, or on recruitment and mortality of perennial grasses. However, at some times of observation addition of P increased ground cover and/or the basal circumference of some perennial grass species. Basal circumference for Enteropogon acicularis was also increased by addition of N. Soil biological activity, measured by decomposition of cotton strips, was increased by addition of N, which maintained vegetation in an annual-dominated condition, and was not affected by addition of P. Carbon addition has the potential to assist restoration of this grassland. However, the capacity of some native grass species to respond to increased fertility suggests that once restoration is achieved some increase in fertility may be beneficial for pastoral production.

The importance of plant density, plant basal area and plant mass per unit basal area as factors influencing the herbage mass of some native perennial grasses.

1982 ◽  
Vol 4 (2) ◽  
pp. 61 ◽  
Author(s):  
GM Lodge ◽  
AC Gleeson
Keyword(s):  
Plant Density ◽  
Basal Area ◽  
Perennial Grasses ◽  
Green Leaf ◽  
Relative Significance ◽  
Mass Estimate ◽  
Component Field ◽  
The Mean ◽  
The Individual ◽  
Green Stem

Four native perennial grasses, Aristida ramosa R.Br. (wire grass), Bothrioc.llloa macra (Steud) S.T. Blake (red grass), Spovo- bolus elongatus R.Br. (slender rats tail grass) and Stipa variabilis Hughes (corkscrew grass) were collected from 60 randomly allocated quadrats (0.16 m2) in a grazed unfertilized native pasture in November 1979. In each quadrat all plants of each species were counted, harvested individually and their basal areas were estimated. The mass of green leaf, green stem, dead herbage and total herbage of each species was estimated using the mean mass of the individual plants harvested in each of the quadrats. A method for determining the relative importance of the components of this herbage mass viz. plant density, basal area and mass per unit basal area is presented and these values are compared for each species. Plant density contributed significantly fP <0.05) to green leaf, green stem, dead and total herbage mass estimates of A. ramosa and S. elongatus; basal area to all herbage mass estimates of A. ramosa, S. elongatus and S. variabilis; and mass per unit basal area to all herbage mass estimates of A. ramosa and B. macra. The plant basal area of individual plants contributed signifi- cantly more (P <0.05) to the herbage mass estimate of S. vaviabilis and S, elongatus plants than did mass per unit basal area, whereas for B. rnacra mass per unit basal area was the significant (P < 0.05) component. Field procedures for estimating herbage mass and assessing the relative significance of its components are discussed and the extra time taken to collect plant density, plant basal area, and plant mass per unit basal area datais outlined.

Techniques for estimating plant basal area and assessing the herbage mass of some native perennial grasses.

1981 ◽  
Vol 3 (1) ◽  
pp. 83 ◽  
Author(s):  
GM Lodge ◽  
JA Taylor ◽  
RDB Whalley
Keyword(s):  
Plant Density ◽  
Unit Area ◽  
Basal Area ◽  
Ground Level ◽  
Field Studies ◽  
Fertilizer Application ◽  
Perennial Grasses ◽  
Individual Species ◽  
Laboratory Studies ◽  
Plant Parts

Techniques for using grid and unmarked transparent perspex overlays to estimate the area of tufted native perennial grasses were investigated in field and laboratory studies. Basal area was overestimated by using an unmarked overlay to trace the periphery of actual or atificial plant bases at ground level; this was caused by the amount of airspace included in the estimate. The compression of hand-held tufts reduced the airspace and improved the estimate of plant basal area. In the laboratory studies, the estimation by eye of filled cells in a transparent grid overlay was accurate over a range of areas from 0.02 to 10.39 cm2, although it required considerable operator training. Changes in herbage mass occur as a result of change in the number of plants per unit area (plant density), the basal area of individual plants or the plant mass per unit of basal area of individual plants. Field studies were undertaken at two sites to collect data on each of these components of herbage mass and to investigate whether or not such information could be used to estimate the herbage mass of individual species in a pasture. The relationship between the mass per unit basal area of certain plant parts would appear to have some potential for use in studies of the seasonal changes in various plant components, such as green leaf and stem. This relationship could be used to examine the response of some species to fertilizer application, grazing and defoliation and hence the process of change in species composition with management. Estimates of the herbage mass per unit area of individual native perennial grasses calculated from plant density, plant basal area and mass per unit of basal area data compared favourably with estimates of total herbage mass of individual species obtained from clipped quadrats. Suggested techniques for collecting data in the field and the time involved in sampling are discussed.

The role of plant mass, basal area and density in assessing the herbage mass response to fertility of some native perennial grasses.

1981 ◽  
Vol 3 (1) ◽  
pp. 92 ◽  
Author(s):  
GM Lodge
Keyword(s):  
Field Experiments ◽  
Plant Density ◽  
Basal Area ◽  
Perennial Grasses ◽  
Green Leaf ◽  
Density Data ◽  
Leaf Mass ◽  
Pot Culture

The effects of nitrogen (N) application and differing past fertilizer history on the ,preen leaf mass per plant, plant basal area, green leaf mass per unit of plant basal area and the plant density of some native perennial grasses were investigated in pot culture and field experiments. Data on each of these components of herbage mass were assessed, either individually or in combination with each other, as methods of evaluating the responsiveness of some native perennial grasses to increased fertility. Different mechanisms of increasing plant green leaf mass with applied N (pot culture) and superphosphate (field) were deter- mined in different species and these affected the relationship between green leaf mass anti basal area. Species such as Aristida ramosa and Bothriochloa macra increased their green leaf mass per unit of plant basal area but not their plant basal area. In the glasshouse the application of N significantly (P<0.05) increased the basal area of Chloris truncata, Eragrostis leptostachya, Dichanthium sericeum, Sporoholus elongatus, Danthonia linkii and Stipa variabilis. However, in the field long-term superphosphate application only significantly increased the basal area of C. truncata and D. linkii plants. In the field the mean densities of A. ramosa, D. sericeum and C. truncata plants growing at the unfertilized site were significantly higher than those at the fertilized site and the density of E. leptostachya plants was significantly higher (P<0.01) at the fertilized site. These data indicated that the use of either mass per plant, mass per unit basal area, plant basal area or plant density alone could bias the apparent responsiveness of some species to fertility. To accurately determine the effect of management on the herbage mass of individual native perennial grasses in the field either mass per plant and plant density data, or mass per unit basal area, basal area and plant density data should be combined.

Floristic composition and pasture condition of Aristida/Bothriochloa pastures in central Queensland. I. Pasture floristics

2015 ◽  
Vol 37 (2) ◽  
pp. 199 ◽  
Author(s):  
R. G. Silcock ◽  
T. J. Hall ◽  
P. G. Filet ◽  
A. M. Kelly ◽  
D. Osten ◽  
...  
Keyword(s):  
Plant Density ◽  
Perennial Grass ◽  
Quantitative Description ◽  
Floristic Composition ◽  
Perennial Grasses ◽  
True Nature ◽  
Heteropogon Contortus ◽  
Crown Cover ◽  
Native Pastures ◽  
A Site

A survey was conducted in central inland Queensland, Australia of 108 sites that were deemed to contain Aristida/Bothriochloa native pastures to quantitatively describe the pastures and attempt to delineate possible sub-types. The pastures were described in terms of their floristic composition, plant density and crown cover. There were generally ~20 (range 5–33) main pasture species at a site. A single dominant perennial grass was rare with three to six prominent species the norm. Chrysopogon fallax (golden-beard grass) was the perennial grass most consistently found in all pastures whereas Aristida calycina (dark wiregrass), Enneapogon spp. (bottlewasher grasses), Brunoniella australis (blue trumpet) and Panicum effusum (hairy panic) were all regularly present. The pastures did not readily separate into broad floristic sub-groups, but three groups that landholders could recognise from a combination of the dominant tree and soil type were identified. The three groups were Eucalyptus crebra (narrow-leaved ironbark), E. melanophloia (silver-leaved ironbark) and E. populnea (poplar box). The pastures of the three main sub-groups were then characterised by the prominent presence, singly or in combination, of Bothriochloa ewartiana (desert bluegrass), Eremochloa bimaculata (poverty grass), Bothriochloa decipiens (pitted bluegrass) or Heteropogon contortus (black speargrass). The poplar box group had the greatest diversity of prominent grasses whereas the narrow-leaved ironbark group had the least. Non-native Cenchrus ciliaris (buffel grass) and Melinis repens (red Natal grass) were generally present at low densities. Describing pastures in terms of frequency of a few species or species groups sometimes failed to capture the true nature of the pasture but plant abundance for most species, as density, herbage mass of dry matter or plant crown cover, was correlated with its recorded frequency. A quantitative description of an average pasture in fair condition is provided but it was not possible to explain why some species often occur together or fail to co-exist in Aristida/Bothriochloa pastures, for example C. ciliaris and E. bimaculata rarely co-exist whereas Tragus australianus (small burrgrass) and Enneapogon spp. are frequently recorded together. Most crown cover was provided by perennial grasses but many of these are Aristida spp. (wiregrasses) and not regarded as useful forage for livestock. No new or improved categorisation of the great variation evident in the Aristida/Bothriochloa native pasture type can be given despite the much improved detail provided of the floristic composition by this survey.

Using fire to manage species composition in Heteropogon contortus (black speargrass) pastures. 1. Burning regimes

1997 ◽  
Vol 48 (6) ◽  
pp. 795 ◽  
Author(s):  
D. M. Orr ◽  
C. J. Paton ◽  
A. T. Lisle
Keyword(s):  
Species Composition ◽  
Plant Density ◽  
Basal Area ◽  
Heteropogon Contortus ◽  
Grazed Pastures ◽  
Pasture Degradation ◽  
Stocking Rates

A reduction in the proportion of the desirable grass Heteropogon contortus(black speargrass) and an increase in the undesirable Aristidaspp . (wiregrasses) are evident in commercially grazed pastures. This paper evaluates the effectiveness of spring burning regimes over a period of 4 years (1989-92) in reversing this form of pasture degradation. Burning increased the proportion of H. contortus when pastures remained ungrazed but not when pastures were grazed, because cattle selectively grazed H. contortus after burning. Burning reduced the proportion of Aristida spp and other undesirable grasses such as Bothriochloa decipiens and Chloris divaricata. A strong ‘year of burning’ effect was evident. Burning increased recruitment of H. contortus which, in turn, increased plant density and later basal area. Burning reduced the basal area of Aristida spp initially by reducing tussock size and later by reducing tussock numbers. Results indicate that spring burning can restore pasture composition and that burning in at least 2 successive years appears to be necessary. Light stocking rates should be adopted so that the proportion of H. contortuscan be maintained and so that pastures can be burnt when and if required.

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.

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