Effects of sheep grazing Astrebla grassland in central western Queensland. 1. Effects of grazing pressure and livestock distribution

1980 ◽  
Vol 31 (4) ◽  
pp. 797 ◽  
Author(s):  
DM Orr
Keyword(s):  
Basal Area ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Plant Responses ◽  
Sheep Grazing ◽  
Regular Grid ◽  
Heavy Grazing ◽  
Grazing Pressures ◽  
Light Medium

The effects of grazing pressure on plant responses and livestock distribution in Astrebla grassland were determined from paddocks subject to commercial grazing by sheep at light, medium or heavy grazing pressure. Increased grazing pressure reduced the projected foliage cover of Astrebla spp., the basal area of which was similar under light and medium grazing pressure, and was reduced under heavy grazing pressure. Differences in the density and size of Astrebla spp. tussocks were apparent under the three grazing pressures. Other perennial grasses, notably Aristidu latifolia and A. leptopoda, were most frequent under light grazing pressure. Numerical classification of the sampling sites, which were arranged on a regular grid, allowed the grazing pattern to be established. Heavy utilization was shown to be associated with wind direction, shade availability and watering facilities.

Demography of three perennial grasses in a central Queensland eucalypt woodland

2009 ◽  
Vol 31 (4) ◽  
pp. 427 ◽  
Author(s):  
P. Jones ◽  
P. Filet ◽  
D. M. Orr
Keyword(s):  
Life Span ◽  
Seedling Recruitment ◽  
Negative Impact ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Seasonal Rainfall ◽  
Severe Drought ◽  
Heteropogon Contortus ◽  
Heavy Grazing ◽  
Eucalypt Woodland

The population dynamics of the palatable, perennial grasses Bothriochloa ewartiana (Domin) C.E.Hubb. (desert Mitchell grass), Chrysopogon fallax S.T.Blake (golden beard grass) and Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. (black speargrass), were studied in an extensive grazing study conducted in a eucalypt woodland within the Aristida–Bothriochloa pasture community in central Queensland between 1994 and 2000. Treatments were three grazing pressures based on light, medium and heavy utilisation of forage available at the end of summer and two timber treatments (trees intact and trees killed). Seasonal rainfall throughout this study was generally favourable for plant growth with no severe drought periods. Grazing pressure had a greater overall impact on plant dynamics than timber treatment, which had minimal impact. Grazing pressure had a large impact on H. contortus dynamics, an intermediate impact on B. ewartiana and no impact on C. fallax. Fluctuations in plant density of both B. ewartiana and C. fallax were small because both species were long lived with low levels of seedling recruitment and plant death, whereas fluctuations in H. contortus density were relatively high because of its relatively short life span and higher levels of both recruitment and death. Heavy grazing pressure increased the recruitment of B. ewartiana and H. contortus in some years but had no impact on that of C. fallax. Heavy grazing pressure reduced the survival of the original plants of both B. ewartiana and H. contortus but not of C. fallax. For H. contortus, the size of the original plants was larger where trees were killed than where trees were left intact and plants of the 1995 seedling cohort were larger in 1998 at heavy compared with those at light and medium grazing pressure. Grazing had a minor negative impact on the soil seed bank of H. contortus. Populations of all three species remained stable throughout this study, although the favourable seasonal rainfall experienced and the short duration of this study relative to the life span of these species may have masked longer term, deleterious impacts of heavy grazing pressure.

scholarly journals Plant Diversity and Chemical Soil Composition of Rocky Pastures in Relation to the Sheep Grazing Intensity on the Northern Adriatic Islands (Croatia)

2014 ◽  
Vol 73 (2) ◽  
pp. 419-435 ◽  
Author(s):  
Ivica Ljubičić ◽  
Mihaela Britvec ◽  
Sven D. Jelaska ◽  
Stjepan Husnjak
Keyword(s):  
Plant Diversity ◽  
Vascular Plants ◽  
Grazing Intensity ◽  
Grazing Pressure ◽  
Sheep Grazing ◽  
Soil Composition ◽  
Northern Adriatic ◽  
Abundance Patterns ◽  
Heavy Grazing ◽  
Chemical Soil

Abstract Optimal grazing pressure on rocky pastures is beneficial to the development of plant species and maintenance of plant diversity. Both abandonment of grazing and overgrazing gradually reduce plant diversity. This paper correlated abundance patterns of the flora on rocky pastures with the values of the chemical composition of the soil resulting from the degree of sheep grazing intensity. The study was carried out in the period from 2008 to 2010 on the islands of Pag, Krk and Cres. At 30 sites, 310 taxa of vascular plants were found. The highest plant diversity and 220 plant taxa were found on moderately grazed pastures. Abandoned pastures with a total of 93 plant taxa observed show the dominance of phanerophytes (35.5%) and the highest proportion of the Mediterranean floral element when compared to pastures of moderate and heavy grazing intensity. The highest concentration of total nitrogen in the soil (0.71%) was recorded on plots of heavy grazing intensity. The results of the study indicate that moderate grazing intensity, from 1 to 1.5 sheep ha−1, can be recommended on the northern Adriatic islands. This should contribute not only to the preservation of plant diversity, but also to the improvement of ecological sheep farming.

Selection of diet by sheep grazing semi-arid pastures on the Riverine Plain. 4. A grassland (Danthonia caespitosa) community

1967 ◽  
Vol 7 (28) ◽  
pp. 426 ◽  
Author(s):  
GW Robards ◽  
JH Leigh ◽  
WE Mulham
Keyword(s):  
Nitrogen Content ◽  
Grazing Pressure ◽  
In Vitro Digestibility ◽  
Sheep Grazing ◽  
Resistant Species ◽  
Heavy Grazing ◽  
Visual Assessments ◽  
Selection Of

The diet selected by Merino sheep grazing a Danthonia caespitosa Gaudich. grassland was determined by analysing extrusa from Merino wethers fitted with oesophageal fistulas. Visual assessments were combined with hand clipped samples to determine the amount of forage available. In spring a large proportion of the diet consisted of annual species. In summer, when the range of species present in the pasture was low, Danthonia caespitosa made up the bulk of the diet. Under heavy grazing the amount of dry material and burrs of Medicago polymorpha L. in the diet increased as the supply of Danthonia caespitosa decreased. Nitrogen content and in vitro digestibility, both of the pasture and of the forage eaten during spring, decreased as forage availability decreased under heavy grazing. These values were lower in summer than in spring, but showed little change under increasing grazing pressure. The quality of the pasture, as assessed by nitrogen content and digestibility, would have been sufficient, even in the dry summer experienced during this study, to enable sheep to increase in body weight. Because of the lack of drought-resistant species capable of producing appreciable amounts of forage in the summer-autumn period, it is improbable that any system of management based on deferred or rotational grazing can be devised that will increase animal production from this pasture type.

Effect of livestock grazing on physical properties of a cracking and self-mulching Vertisol

2002 ◽  
Vol 42 (2) ◽  
pp. 129 ◽  
Author(s):  
G. Taddese ◽  
M. A. Mohamed Saleem ◽  
W. Ayalneh
Keyword(s):  
Moisture Content ◽  
Physical Properties ◽  
Addis Ababa ◽  
Grazing Pressure ◽  
Livestock Grazing ◽  
Control Treatment ◽  
Soil Matrix ◽  
Heavy Grazing ◽  
The Impact ◽  
Grazing Pressures

The impact of grazing on physical properties of Vertisol was studied from 1996 to 2000 in the Ethiopian highlands. The study was conducted at 2 sites with 0–4 and 4–8% slopes at Tero Jemjem watershed in Ginchi, 80 km west of Addis Ababa. The objective of the study was to compare selected soil physical properties at different grazing pressures and slopes. The stocking rate was moderate grazing 1.8 animal-unit months per hectare (1.8 AUM/ha), heavy grazing 3.0 AUM/ha and a control treatment with no grazing. The result showed that heavy grazing pressure removed grass cover, which consequently enhanced soil cracking. Effect of livestock trampling on soil resistance to penetration (indicated by penetrometer readings) was higher in the heavily grazed plots than in non-grazed plots. Penetrometer readings were influenced by soil moisture content. Low moisture content was observed in the heavily grazed plots at both sites. The infiltration of accumulated water to the soil matrix was lower in heavily grazed plots.

Effect of sheep grazing Astrebla grassland in central western Queensland. 2. Effects of seasonal rainfall

1980 ◽  
Vol 31 (4) ◽  
pp. 807 ◽  
Author(s):  
DM Orr
Keyword(s):  
Regression Analysis ◽  
Basal Area ◽  
Summer Rainfall ◽  
Tribulus Terrestris ◽  
Sheep Grazing ◽  
Annual Grass ◽  
Dry Period ◽  
Average Rainfall ◽  
Annual Grasses ◽  
Grazing Pressures

The response of Astrebla grassland pasture to summer rainfall was measured at sites in commercially grazed paddocks which were subject to different grazing pressures. The interrelationship between forage use and plant variates was examined by regression analysis. Above-average rainfall resulted in increases in basal area and projected foliage cover of Astrebla spp. under grazing pressures equivalent to 50% forage use of A. lappacea. Increased forage use in the dry period before this rainfall reduced the basal area and projected foliage cover of Astrebla and resulted in lower yields of Astrebla following the rainfall. These lower yields of Astrebla were associated with higher yields of annual grasses and forbs than where forage use had been light. Astrebla yields were highest under light forage use. The frequency of two undesirable species, Amaranthus niitchellii and Tribulus terrestris, was highest under heavy forage use, and was associated with a decline in the number of other annual grass and forb species.

A survey of the natural pastures of the Trangie District, New South Wales, with particular reference to the grazing factor.

1953 ◽  
Vol 4 (1) ◽  
pp. 1 ◽  
Author(s):  
EF Biddiscombe
Keyword(s):  
Perennial Grass ◽  
Grazing Intensity ◽  
Basal Area ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Forage Production ◽  
South Wales ◽  
Wide Range ◽  
Grazing Intensities ◽  
Summer Maximum

The Trangie district has a rainfall of 1,750 points with a slight summer maximum, a high relative variability of rainfall, and high summer temperatures. Disclimax pasture communities produced by a range of sheep grazing intensities operative during the past 20-30 years are described. On light soils ungrazed pasture comprises a wide range of perennial grasses. Light grazing (1 sheep per 2 acres) gives increased dominance by Stipa fulcata. With successive increases in grazing pressure Chloris acicdaris and Stipa setacea become conspicuous in turn, only to be virtually replaced by Chloris trumata as grazing intensity reaches 1 sheep per 0.5 acre. On heavy soils Stipa aristiglumis is dominant under light grazing. With increased rate of stocking, first Sporobolus caroli and then Stipa setacea gain dominance. At the highest stocking rates all these species are largely replaced by Chloris truncata. Throughout the sere the number of species is far more restricted than on the light soils. The striking feature of these results is that though botanical composition of the perennial grass component on light and heavy soils respectively is vastly different under light grazing, it becomes similar under heavy grazing and almost identical under severe grazing. Degenerative changes common to pastures of both soil groups under increasing grazing pressure are the decline in density and basal area of the perennial grass component, the greater population of winter and summer annuals, and the declining contribution of perennial grasses to green forage production in the spring. The basis of these findings is firstly the measurement of basal area, density and yield of perennial grasses, and density and yield of annual species in pastures of varying stocking history, and secondly, the measurement of pasture composition in relation to increasing distance from watering points.

Rangeland responses to pastoralists' grazing management on a Tibetan steppe grassland, Qinghai Province, China

2016 ◽  
Vol 38 (1) ◽  
pp. 1 ◽  
Author(s):  
Richard B. Harris ◽  
Leah H. Samberg ◽  
Emily T. Yeh ◽  
Andrew T. Smith ◽  
Wang Wenying ◽  
...  
Keyword(s):  
Plant Species ◽  
Temporal Trends ◽  
Winter Season ◽  
Grazing Pressure ◽  
Livestock Grazing ◽  
Western China ◽  
Permanent Plots ◽  
Sheep Grazing ◽  
Qinghai Province ◽  
Preferred Species

Livestock grazing is the principal land use in arid central Asia, and range degradation is considered a serious problem within much of the high-elevation region of western China termed the Qinghai-Tibetan Plateau (QTP). Rangeland degradation on the QTP is variously attributed to poor livestock management, historical-cultural factors, changing land tenure arrangements or socioeconomic systems, climate change, and damage from small mammals. Few studies have examined currently managed pastures using detailed data capable of isolating fine-scale livestock–vegetation interactions. The aim of the study was to understand how differences among livestock (primarily sheep) management strategies of pastoralists during winter affected subsequent rangeland condition and productivity. Plant species composition, annual herbage mass, and indicators of erosion were quantified during four summers (2009–2012) on winter pastures managed by 11 different pastoralists on QTP steppe rangeland in Qinghai Province, China. Data came from repeated-measurements on 317 systematically located permanent plots, as well as pastoralist interviews and the use of GPS-equipped livestock. Relationships between annual weather variation and herbage mass were modelled using an independent set of vegetation measurements obtained from livestock exclosures. Account was taken of inherent site differences among pastures. Annual variation in herbage mass was found to be best fitted by a model containing a negative function of winter-season temperature and a positive function of spring-season temperature. Accounting for annual and site effects, significant differences among pastoralists were found for most response variables, suggesting that individual heterogeneity among management approaches had consequences, even among neighbouring pastoralists. Annual herbage mass of preferred plant species was positively associated, whereas that of unpreferred species was negatively associated, with mean sheep density and intensity of use. However, the proportion of bare soil, an index of erosion, and annual herbage mass of unpreferred forbs were found to have positive relationships with sheep grazing pressure during the preceding winter, whereas live vegetation cover and annual herbage mass of preferred grasses were negatively related. Thus, on a spatial scale, pastoralists responded adaptively to the cover of preferred plant species while not responding to total annual herbage mass. Pastoralists stocked pastures more heavily, and livestock used regions within pastures more intensively, where preferred species had a higher cover. However, where sheep grazing pressure was high, downward temporal trends in the herbage mass of preferred species were exacerbated. Pastures that were stocked at a lower density did not experience the negative trends seen in those with a higher density.

Persistence and growth of Lotononis bainesii–Digitaria decumbens pastures: 1. Sheep stocking rate

1983 ◽  
Vol 101 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. Pott ◽  
L. R. Humphreys
Keyword(s):  
Bulk Density ◽  
Soil Bulk Density ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Digitaria Decumbens ◽  
Heavy Grazing ◽  
Cotton South ◽  
Seed Reserves ◽  
Stocking Rates

SUMMARYSheep were grazed for 2 years at stocking rates of 7, 14, 21 and 28/ha on a pasture comprising Lotononis bainesii and Digitaria decumbens cv. Pangola at Mt Cotton, south–east Queensland. There were six replicates of each treatment grazed in rotation with 3 days' grazing followed by 15 days' rest.The initial dominance of lotononis was lost after 6 months of grazing and lotononis failed to persist satisfactorily at any stocking rate. Demographic studies showed that lotononis behaved as a short-lived plant, predominantly annual, with some vegetative perennation as stolon-rooted units under heavy grazing. Soil seed reserves varied from 5800 to 400 m2 at the lightest and heaviest stocking rates respectively. Lotononis failed to regenerate under Pangola shading or inopportune high grazing pressure. Soil bulk density (0–7 cm) increased from 1·2 to 1·4 g/cm3 according to stocking rate.

scholarly journals Physiological Implications of Hydrogen Sulfide in Plants: Pleasant Exploration behind Its Unpleasant Odour

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Zhuping Jin ◽  
Yanxi Pei
Keyword(s):  
Hydrogen Sulfide ◽  
Growth And Development ◽  
Defense Responses ◽  
Plant Responses ◽  
Plant Growth And Development ◽  
Systematic Classification ◽  
Physiological Processes ◽  
Overwhelming Evidence

Recently, overwhelming evidence has proven that hydrogen sulfide (H2S), which was identified as a gasotransmitter in animals, plays important roles in diverse physiological processes in plants as well. With the discovery and systematic classification of the enzymes producing H2Sin vivo, a better understanding of the mechanisms by which H2S influences plant responses to various stimuli was reached. There are many functions of H2S, including the modulation of defense responses and plant growth and development, as well as the regulation of senescence and maturation. Additionally, mounting evidence indicates that H2S signaling interacts with plant hormones, hydrogen peroxide, nitric oxide, carbon monoxide, and other molecules in signaling pathways.

scholarly journals The search for alternative temperate perennial pasture species for low to medium rainfall environments in Tasmania

2016 ◽  
Vol 16 ◽  
pp. 275-279
Author(s):  
E.J. Hall ◽  
R. Reid ◽  
B. Clark ◽  
R. Dent
Keyword(s):  
Perennial Grass ◽  
Dactylis Glomerata ◽  
Red Clover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Sheep Grazing ◽  
Cool Temperate ◽  
Perennial Legume ◽  
Perennial Legumes ◽  
Pasture Plants

In response to the need to find better adapted and more persistent perennial pasture plants for the dryland pastures in the cool-temperate low to medium rainfall (500-700 mm) regions, over 1000 accessions representing 24 species of perennial legumes and 64 species of perennial grasses, were introduced, characterised and evaluated for production and persistence under sheep grazing at sites throughout Tasmania. The work has identified four alternative legume species in Talish Clover (Trifolium tumens). Caucasian Clover (T. ambiguum), Stoloniferous Red Clover (T. pratense var. stoloniferum), Lucerne x Yellow Lucerne Hybrid (Medicago sativa x M.sativa subsp. falcata); and two grass species in Coloured Brome (Bromus coloratus) and Hispanic Cocksfoot (Dactylis glomerata var hispanica). Keywords: persistence, perennial grass, perennial legume

Sign in / Sign up

Export Citation Format

Share Document