Grassland dynamics under sheep grazing in an Australian Mediterranean type climate

Austin, M. P.; Williams, O. B.; Belbin, Lee

doi:10.1007/bf00118398

Cited by 69 publications

(38 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A 20 yr study of sheep grazing in a degraded disclimax grassland in Australia dominated by Danthonia caespitosa found grazing intensity had no effect on successional trajectories (Austin et al 1981). Our ordination trajectories illustrate clear trends which support research identifying March-April grazing as an important cause of retrogression in the salt desert shrub ecosystem.…”

Section: Discussionsupporting

confidence: 70%

Successional trajectories of a grazed salt desert shrubland

Whisenant

Wagstaff

1991

Vegetatio

View full text Add to dashboard Cite

Successional trajectories through the statistical space of ordinations were used to examine response to grazing in salt desert shrub communities of western Utah, USA. Relative cover data were periodically collected over a 53 year period from grazing exclosures and pastures grazed with light or heavy stocking rates in fall or spring (4 grazing treatments). Two-way indicator species analysis was used to select the 98 most similar plots (24 m 2) from among 358 plots in 1935. Foliar cover of 23 species on those 98 plots was followed at irregular intervals over 53 years, resulting in 709 plot-time samples. Successional trajectories were developed for each grazing treatment with ordinations from detrended correspondence analysis. Grazing season had a more pronounced influence on floristic trajectories than did grazing intensity. These ordinations suggest grazing season was an important factor regulating response to grazing and identify annual March-April grazing as an important cause of retrogression in the salt desert shrub ecosystem.

show abstract

Section: Discussionsupporting

confidence: 70%

Successional trajectories of a grazed salt desert shrubland

Whisenant

Wagstaff

1991

Vegetatio

View full text Add to dashboard Cite

show abstract

“…These patterns occurred over a time span that incorporated a severe drought during the early 1950s followed by several years of above-average precipitation. Previous studies of grassland dynamics in the absence of grazing have demonstrated that quantitative changes in vegetation may occur rapidly (Penfound 1964;Austin et al 1981;Collins & Adams 1983;Biondini et al 1985) or slowly (West etal. 1979;Glenn-Lewin 1980;Holechek & Stephenson 1983).…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have documented patterns during secondary succession in grassland vegetation (e.g., Bassett 1980;Austin et al 1981;Chew 1982;Reichhardt 1982;Collins & Adams 1983;Potvin & Harrison 1984;West et al 1984;Biondini et al 1985). Few generalizations have emerged from these studies, perhaps because vegetation dynamics in arid and semi-arid systems is influenced more by abiotic than biotic factors (MacMahon 1980).…”

Section: Introductionmentioning

confidence: 99%

“…Few generalizations have emerged from these studies, perhaps because vegetation dynamics in arid and semi-arid systems is influenced more by abiotic than biotic factors (MacMahon 1980). For example, Austin et al (1981) indicated that climate had a significant effect on succession in Australian grasslands, and Chew (1982) reported that infrequent climatic events confounded patterns of vegetation change in desert grasslands. Van der Maarel (1981) found a rapid response to wet and dry treatments in dune grasslands.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Succession and fluctuation in Artemisia dominated grassland

1988

View full text Add to dashboard Cite

Vegetation dynamics were studied from 1940 to 1978 in two grazed pastures and associated exclosures in sand sagebrush (Artemisiafilifolia) dominated grassland, western Oklahoma, USA. In both pastures and one exclosure, pattern of vegetation change reflected fluctuation rather than succession. In the other exclosure, the grassland exhibited a directional change from annual grasses and forbs to dominance by perennial grasses. Rate of change was consistent during the 39 year period. Cover of grasses increased more in grazed than ungrazed areas. Grass cover was negatively correlated with high air temperatures early in the growing season. Forb cover remained relatively constant over time and shrub cover peaked during the 1960s. Abundance of annuals and cool season species was positively correlated with rainfall early in the growing season.Species diversity and richness were lowest in the ungrazed areas, as a result of increased dominance by perennial grasses such as Schizachyrium scoparium. In pastures and exclosures, richness was positively correlated with growing season precipitation. Cover of the common species differed among sample areas within years and fluctuated between years. Few general patterns emerged from correlations of environmental variables with cover of individual species. In general, vegetation dynamics in these sand sagebrush grasslands reflect a tradeoff in that total cover changes little over time because the loss of some species is compensated for by increased growth of others. Such trade-offs reflect the individualistic response of the component species within each pasture or exclosure. Although changes in growth form composition were related to climatic fluctuation, broadscale climatic variables could not successfully predict small-scale patterns of change by individual species over time.Nomenclature follows Gould (1975), The grasses of Texas, College Station TX, and Waterfall (1972), Keys to the flora of Oklahoma, Stillwater OK.

show abstract

“…Data on the grazing effect is contradictory (e.g. Austin et al 1981;Mott et al 1992;Eneboe et al 2002) and this needs resolution. The conceptual death trap model was earlier proposed (Hodgkinson 1995) to account for the death response from the combination of grazing and drought stresses.…”

Section: Towards a Grass Death Modelmentioning

confidence: 99%

Death model for tussock perennial grasses: a rainfall threshold for survival and evidence for landscape control of death in drought

Hodgkinson

Müller

2005

Rangel. J.

View full text Add to dashboard Cite

Abstract. We investigated relationships between rainfall (and landscape, zonation and nearby grazing disturbance) and the death rates of four perennial grass species in a highly functional semi-arid wooded grassland in eastern Australia. Two grasses were palatable C 3 species (Monachather paradoxa Steud. and Thyridolepis mitchelliana (Nees) S. T. Blake) and two were unpalatable C 4 species (Aristida jerichoensis (Domin) Henr. var. subspinulifera Henr. and Eragrostis eriopoda Benth.). During the 10-year study the grasses were protected from large herbivore grazing within paddocks continuously grazed by sheep. Death occurred only during droughts and rates of death were species-dependent. When plotted against several water availability indices, rainfall and rainfall/evaporation during the preceding 3 months provided best predictions of death. Longer preceding periods gave inferior predictions. A 3-month rainfall total of 75 mm and a 3-month rainfall/evaporation ratio of 0.15 were survival critical thresholds below which deaths began. The 3-month rainfall totals, rainfall/evaporation and estimated water status of plants were equally reasonable predictors of deaths, but were inconsistent in their effectiveness. Rainfall was adopted for the grass death model; death begins when 3-month rainfall total declines below a threshold of 75 mm and the death rate rises with lower rainfall. Position of plants in the gently undulating landscapes influenced water status and, hence, death rates. Water status of grasses on the two water-shedding zones and the 'flat' zone were similar at each assessment, but higher on 'ridge run-on' and 'toe-of-slope' zones. Foliage height and diameter also influenced death rate but were species dependent. Basal diameter did not influence death rate. Survivorship of several perennial grass species at widely spaced sites in south-eastern Australia provided equivocal support for generality of the grass death model.

show abstract

Grassland dynamics under sheep grazing in an Australian Mediterranean type climate

Cited by 69 publications

References 28 publications

Successional trajectories of a grazed salt desert shrubland

Successional trajectories of a grazed salt desert shrubland

Succession and fluctuation in Artemisia dominated grassland

Death model for tussock perennial grasses: a rainfall threshold for survival and evidence for landscape control of death in drought

Contact Info

Product

Resources

About