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.

Effects of Sheep Grazing Astrebla Grasslands in Central Western Queensland. Iii. Dynamics of Astrebla Spp. Under Grazing and Exclosure Between 1975 and 1986.

1991 ◽  
Vol 13 (1) ◽  
pp. 36 ◽  
Author(s):  
DM Orr ◽  
CJ Evenson
Keyword(s):  
Population Dynamics ◽  
Seed Production ◽  
Basal Area ◽  
Summer Rainfall ◽  
High Variability ◽  
Plant Population ◽  
Sheep Grazing ◽  
Plant Population Dynamics ◽  
Winter Rainfall ◽  
Plant Populations

The basal area, yield and plant populations of Astrebla spp. were monitored under grazing and exclosure in Astrebla grasslands between 1975 and 1986. This study was undertaken to develop an understanding of how Astrebla spp. respond to grazing, particularly in relation to the high variability of rainfall. Basal area and yield of Astrebla spp. varied widely between years in response to summer rainfall, with few differences between exclosure and grazing. The failure of summer rainfall resulted in increased utilization of Astrebla spp. but this effect was partially offset in some years by the growth of forb species following winter rainfall. Grazing stimulated the recruitment of Astrebla spp. seedlings by increasing the density of inflorescences which, in turn, increased seed production. Survival of seedling cohorts depended on adequate summer rainfall and grazing tended to enhance cohort survival. There was a greater plant flux under grazing than under exclosure. It was concluded that rainfall is the major factor influencing the biomass and plant population dynamics of Astrebla spp. and that grazing up to about 30% utilization is not detrimental to Astrebla spp.

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.

Effect of chemical removal of grasses from pasture leys on pasture and sheep production

1987 ◽  
Vol 27 (3) ◽  
pp. 349 ◽  
Author(s):  
CW Thorn ◽  
MW Perry
Keyword(s):  
Dry Matter ◽  
Stocking Rate ◽  
Sheep Grazing ◽  
Annual Grass ◽  
Pasture Production ◽  
Wool Production ◽  
Wool Growth ◽  
Annual Grasses ◽  
Sheep Production ◽  
Stocking Rates

Pasture production, pasture composition and quality, and liveweight, body condition and wool growth of Merino weaner wethers were monitored over 2 seasons and at 2 stocking rates (4 and 8 sheep/ha) on a mixed annual grass-legume pasture sprayed with propyzamide to control grasses. Propyzamide virtually eliminated annual grasses from the pasture (less than 5 kg/ha of grass dry matter in spring v. 403 kg/ha on untreated pasture in 1981) and this carried over into the second season (61 kg/ha v. 647 kg/ha in spring 1982). Propyzamide treated pastures had less total dry matter (P = 0.05) throughout 1981: however, except for a single sample date, there was no effect of propyzamide on total available pasture in the second season. Increased growth of clover and capeweed compensated for the absence of the grasses. The higher stocking rate reduced available clover, capeweed and total dry matter (P = 0.05) throughout both years. Sheep grazing grass-free pastures had lower liveweights during winter in both years, but made compensatory gains during late spring and summer consistent with the higher quality (1.6 v. 1.07% nitrogen when sampled in January) of propyzamide treated pastures. In 198 1, wool growth rates were reduced at the higher stocking rate and total clean wool production was reduced from 4.55 kg/sheep at 4/ha to 3.65 kg/sheep at 8/ha. Pasture treatment had no effect on wool production in either year. The implications of using selective herbicides to remove the annual grass component of legume-based annual pastures in south-western Australia are dis cussed in relation to pasture and sheep production.

Herbicides for Postemergence Control of Annual Grass Weeds in Seedling Forage Grasses

Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 375-379 ◽  
Author(s):  
Thomas J. Peters ◽  
Russell S. Moomaw ◽  
Alex R. Martin
Keyword(s):  
Warm Season ◽  
Big Bluestem ◽  
Forage Grasses ◽  
Annual Grass ◽  
Cool Season ◽  
Intermediate Wheatgrass ◽  
Green Foxtail ◽  
Annual Grasses ◽  
Large Crabgrass ◽  
Warm Season Grasses

The control of three summer annual grass weeds with herbicides during establishment of forage grasses was studied near Concord and Mead, NE, in 1984, 1985, and 1986. Three cool-season forage grasses, intermediate wheatgrass, tall fescue, and smooth bromegrass, and two warm-season grasses, big bluestem and switchgrass, were included. The control of three major summer annual grasses, green foxtail, barnyardgrass, and large crabgrass, was excellent with fenoxaprop at 0.22 kg ai/ha. Slight to moderate injury to cool-season forage grasses and severe injury to warm-season grasses were evident. Sethoxydim at 0.22 kg ai/ha and haloxyfop at 0.11 kg ai/ha controlled green foxtail and large crabgrass, but not barnyardgrass. Sulfometuron-treated big bluestem and switchgrass plots had the best forage stand frequencies and yields and, at the rate used, sulfometuron satisfactorily controlled green foxtail but only marginally controlled barnyardgrass and large crabgrass.

Annual Grass Control in Alfalfa (Medicago sativa) with Postemergence Graminicides

1992 ◽  
Vol 6 (4) ◽  
pp. 938-948 ◽  
Author(s):  
Chester L. Foy ◽  
Harold L. Witt
Keyword(s):  
Medicago Sativa ◽  
Field Experiments ◽  
Annual Grass ◽  
Giant Foxtail ◽  
Herbicide Treatments ◽  
Highly Effective ◽  
Annual Grasses ◽  
Large Crabgrass

Field experiments were conducted during 1982 to 1988 in Virginia to evaluate BAS 517, CGA 82725, clethodim, cloproxydim, fenoxaprop, fluazifop, fluazifop-P, haloxyfop, paraquat, quizalofop, SC-1084, sethoxydim, sethoxydim plus thifensulfuron, and terbacil for control of annual grasses in alfalfa. Herbicides were applied to alfalfa and grasses 2 to 30 cm in height after the first and/or second cuttings. Overall, the herbicides were highly effective in controlling fall panicum, giant foxtail, barnyardgrass, and large crabgrass. Alfalfa yields were not increased with herbicide treatments in several experiments. Only paraquat, applied later than recommended after cutting in one experiment, and sethoxydim plus thifensulfuron at one location reduced alfalfa yields.

Effect of Spray Components on Glyphosate Toxicity to Annual Grasses

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Douglas D. Buhler ◽  
Orvin C. Burnside
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Surfactant Concentration ◽  
Growth Stage ◽  
Annual Grass ◽  
Spray Solution ◽  
Annual Grasses ◽  
Small Grains ◽  
Carrier Volume

Field and greenhouse research was conducted during 1980 and 1981 to evaluate the effects of carrier volume, surfactant concentration, and treatment date on glyphosate [N- (phosphonomethyl)glycine] toxicity to annual-grass weeds and volunteer small grains. Glyphosate phytotoxicity increased as carrier volume was decreased from 190 to 24 L/ha. The presence of a surfactant in the spray solution did not influence grass control when glyphosate was applied in a carrier volume of 24 L/ha. When glyphosate was applied in 48 or 95 L/ha, the presence of surfactant resulted in better grass control than glyphosate without surfactant. When applied in 190 L/ha, glyphosate with 0.5% (v/v) surfactant gave better grass control than glyphosate alone or commercially formulated glyphosate. When glyphosate was applied to plants under water stress, little control was achieved regardless of plant growth stage. Glyphosate application to grass after head initiation also resulted in reduced control. Maximum weed control with glyphosate was attained when applications were made to seedlings growing actively because of adequate soil moisture and favorable temperatures.

scholarly journals Effects of the MaxP (TM) endophyte in tall fescue on pasture production and composition, and the sheep grazing preference in a dryland environment

2007 ◽  
Vol 13 ◽  
pp. 259-262
Author(s):  
K.N. Tozer ◽  
S. Ates ◽  
N.R. Mapp ◽  
M.C. Smith ◽  
R.J. Lucas ◽  
...  
Keyword(s):  
New Zealand ◽  
Tall Fescue ◽  
Dry Matter ◽  
Early Spring ◽  
Botanical Composition ◽  
Sheep Grazing ◽  
Pasture Production ◽  
Basal Diameter ◽  
Matter Production ◽  
Annual Grasses

Pasture growth, botanical composition and sheep grazing preference were measured over 20 months in tall fescue (cultivar Advance), without endophyte (Nil) or infected with AR542 (MaxPTM) endophyte, and clover pastures sown into a dryland soil, Canterbury, New Zealand. Pastures were rotationally grazed with sheep, with grazing preference for the two endophyte treatments measured in late autumn and early spring. Annual dry matter production from April 2004 to April 2005 was not significantly different between AR542 (6293 kg DM/ha) and Nil (5864 kg DM/ha) tall fescue. The number of tall fescue plants/m2 and their basal diameter was greater for AR542 (35 plants/m2, 7.5 cm diameter) than Nil endophyte tall fescue (28 plants/m2, 6.8 cm diameter). AR542 endophyte tall fescue pastures had fewer weeds, mainly annual grasses, than Nil endophyte pastures throughout the trial. Grazing preference, measured by the number of sheep grazing each plot, and decline in pasture height did not differ between Nil and AR542 tall fescue. Keywords: tall fescue, novel endophyte, AR542, botanical composition, weed, grazing preference

Restoration of Exotic Annual Grass-Invaded Rangelands: Importance of Seed Mix Composition

2014 ◽  
Vol 7 (2) ◽  
pp. 247-256 ◽  
Author(s):  
Kirk W. Davies ◽  
Dustin D. Johnson ◽  
Aleta M. Nafus
Keyword(s):  
Species Richness ◽  
Life Forms ◽  
Perennial Grasses ◽  
Annual Grass ◽  
Herbaceous Vegetation ◽  
Plant Life ◽  
Annual Grasses ◽  
Exotic Annual Grass ◽  
Resistance To Invasion ◽  
Plant Life Form

AbstractRestoration of exotic annual grass-invaded rangelands is needed to improve ecosystem function and services. Increasing plant species richness is generally believed to increase resistance to invasion and increase desired vegetation. However, the effects of species richness and individual plant life forms in seed mixes used to restore rangelands invaded by exotic annual grasses have not been investigated. We evaluated the effects of seeding different life forms and increasing species richness in seed mixes seeded after exotic annual grass control to restore desirable vegetation (perennial herbaceous vegetation) and limit exotic annual grasses at two sites in southeastern Oregon. We also investigated the effects of seeding two commonly used perennial grasses individually and together on plant community characteristics. Large perennial grasses, the dominant herbaceous plant life form, were the most important group to seed for increasing perennial herbaceous vegetation cover and density. We did not find evidence that greater seed mix species richness increased perennial herbaceous vegetation or decreased exotic annual grass dominance more than seeding only the dominant species. None of the seed mixes had a significant effect on exotic annual grass cover or density, but the lack of a measured effect may have been caused by low annual grass propagule pressure in the first couple of years after annual grass control and an unusually wet-cool spring in the third year post-seeding. Although our results suggest that seeding only the dominant plant life form will likely maximize plant community productivity and resistance to invasion in exotic annual grass-invaded northern Great Basin arid rangelands, seeding a species rich seed mix may have benefits to higher tropic levels and community stability. Clearly the dominant species are the most prudent to include in seed mixes to restore exotic annual grass-invaded plant communities, especially with finite resources and an increasingly large area in need of restoration.

Seasonal climate summary for the southern hemisphere (summer 2017–18): an exceptionally warm season for Australia – a short-lived and weak La Niña

2019 ◽  
Vol 69 (1) ◽  
pp. 351
Author(s):  
Tamika Tihema
Keyword(s):  
Southern Hemisphere ◽  
Warm Season ◽  
Summer Rainfall ◽  
La Niña ◽  
Atmospheric Circulation Patterns ◽  
La Nina ◽  
Circulation Patterns ◽  
Tasman Sea ◽  
Average Rainfall

This is a summary of the southern hemisphere atmospheric circulation patterns and meteorological indices for summer 2017–18; an account of seasonal rainfall and temperature for the Australian region is also provided. A short-lived and weak La Niña developed but decayed by the end of February 2018. Sea-surface temperatures were exceptionally warm in the Tasman Sea from late 2017 to early 2018. It was an exceptionally warm summer for Australia, and the third-warmest mean temperature on record for the nation. Summer rainfall was close to the long-term average for Australia, with aboveaverage rainfall in west and below-average rainfall in the east.

scholarly journals Characterizing Land Surface Phenology and Exotic Annual Grasses in Dryland Ecosystems Using Landsat and Sentinel-2 Data in Harmony

2020 ◽  
Vol 12 (4) ◽  
pp. 725 ◽  
Author(s):  
Neal J. Pastick ◽  
Devendra Dahal ◽  
Bruce K. Wylie ◽  
Sujan Parajuli ◽  
Stephen P. Boyte ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Data Mining ◽  
Land Surface ◽  
Western United States ◽  
Grass Cover ◽  
Annual Grass ◽  
Annual Grasses ◽  
Dryland Ecosystems ◽  
Exotic Annual Grass ◽  
Sentinel 2

Invasive annual grasses, such as cheatgrass (Bromus tectorum L.), have proliferated in dryland ecosystems of the western United States, promoting increased fire activity and reduced biodiversity that can be detrimental to socio-environmental systems. Monitoring exotic annual grass cover and dynamics over large areas requires the use of remote sensing that can support early detection and rapid response initiatives. However, few studies have leveraged remote sensing technologies and computing frameworks capable of providing rangeland managers with maps of exotic annual grass cover at relatively high spatiotemporal resolutions and near real-time latencies. Here, we developed a system for automated mapping of invasive annual grass (%) cover using in situ observations, harmonized Landsat and Sentinel-2 (HLS) data, maps of biophysical variables, and machine learning techniques. A robust and automated cloud, cloud shadow, water, and snow/ice masking procedure (mean overall accuracy >81%) was implemented using time-series outlier detection and data mining techniques prior to spatiotemporal interpolation of HLS data via regression tree models (r = 0.94; mean absolute error (MAE) = 0.02). Weekly, cloud-free normalized difference vegetation index (NDVI) image composites (2016–2018) were used to construct a suite of spectral and phenological metrics (e.g., start and end of season dates), consistent with information derived from Moderate Resolution Image Spectroradiometer (MODIS) data. These metrics were incorporated into a data mining framework that accurately (r = 0.83; MAE = 11) modeled and mapped exotic annual grass (%) cover throughout dryland ecosystems in the western United States at a native, 30-m spatial resolution. Our results show that inclusion of weekly HLS time-series data and derived indicators improves our ability to map exotic annual grass cover, as compared to distribution models that use MODIS products or monthly, seasonal, or annual HLS composites as primary inputs. This research fills a critical gap in our ability to effectively assess, manage, and monitor drylands by providing a framework that allows for an accurate and timely depiction of land surface phenology and exotic annual grass cover at spatial and temporal resolutions that are meaningful to local resource managers.

Sign in / Sign up

Export Citation Format

Share Document