Managing for rainfall variability: effect of grazing strategy on cattle production in a dry tropical savanna

O’Reagain, Peter J.; Bushell, John; Holloway, Chris; Reid, Angela M.

doi:10.1071/ea07187

Cited by 63 publications

(60 citation statements)

References 19 publications

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“…Similarly, the negative response of grass and shrub foraging and nesting species, such as the variegated and red-backed fairy-wrens and the double-barred finch, to heavy grazing simply reaffirms the link between ground cover and abundance of these species (Tassicker et al 2006;Kutt and Martin 2010). In this study, cover was lowest in the most heavily stocked paddocks (O'Reagain et al 2009) and we recorded a reduction in these species due to a grazing effect.…”

Section: Changes In the Vertebrate Faunasupporting

confidence: 59%

Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

Kutt

Vanderduys²,

O’Reagain³

2012

Rangel. J.

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Abstract. Grazing by domestic livestock is one of the most widespread uses of the rangelands of Australia. There is limited information on the effects of grazing by domestic livestock on the vertebrate fauna of Australia and the establishment of a long-term grazing experiment in north-eastern Queensland at Wambiana provided an opportunity to attempt an examination of the changes in vertebrate fauna as a consequence of the manipulation of stocking rates. The aim was to identify what the relative effects of vegetation type, stocking rate and other landscape-scale environmental factors were on the patterns recorded. Sixteen 1-ha sites were established within three replicated treatments (moderate, heavy and variable stocking rates). The sites were sampled in the wet and dry seasons in 1999-2000 (T 0 ) and again in 2003-04 (T 1 ). All paddocks of the treatments were burnt in 1999. Average annual rainfall declined markedly between the two sampling periods, which made interpretation of the data difficult. A total of 127 species of vertebrate fauna comprising five amphibian, 83 bird, 27 reptile and 12 mammal species were recorded. There was strong separation in faunal composition from T 0 to T 1 although changes in mean compositional dissimilarity between the grazing stocking rate treatments were less well defined. There was a relative change in abundance of 24 bird, four mammal and five reptile species from T 0 to T 1 . The generalised linear modelling identified that, in the T 1 data, there was significant variation in the abundance of 16 species explained by the grazing and vegetation factors. This study demonstrated that vertebrate fauna assemblage did change and that these changes were attributable to the interplay between the stocking rates, the vegetation types on the sites surveyed, the burning of the experimental paddocks and the decrease in rainfall over the course of the two surveys. It is recommended that the experiment is sampled again but that the focus should be on a rapid survey of abundant taxa (i.e. birds and reptiles) to allow an increase in the frequency of sampling and replication of the data. This would help to articulate more clearly the trajectory of vertebrate change due to the relative effects of stocking rates compared with wider landscape environmental changes. Given the increasing focus on pastoral development in northern Australia, any opportunity to incorporate the collection of data on biodiversity into grazing manipulation experiments should be taken for the assessment of the effects of land management on faunal species.

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Section: Changes In the Vertebrate Faunasupporting

confidence: 59%

Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

Kutt

Vanderduys²,

O’Reagain³

2012

Rangel. J.

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“…The optimum SR for a particular forage-livestock system will be a compromise between production per individual animal and production per hectare (Inyang et al, 2010). It will also depend upon the production goals over both the short and long terms, and will vary according to the amount and quality of herbage available through seasonal fluctuations as determined by, for example, rainfall and temperature (O'Reagain et al, 2009 and2011).…”

Section: Strategies For Management Of Grasslandsmentioning

confidence: 99%

The importance of grasslands for animal production and other functions: a review on management and methodological progress in the tropics

Boval

Dixon

2012

Animal

175

106

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The global importance of grasslands is indicated by their extent; they comprise some 26% of total land area and 80% of agriculturally productive land. The majority of grasslands are located in tropical developing countries where they are particularly important to the livelihoods of some one billion poor peoples. Grasslands clearly provide the feed base for grazing livestock and thus numerous high-quality foods, but such livestock also provide products such as fertilizer, transport, traction, fibre and leather. In addition, grasslands provide important services and roles including as water catchments, biodiversity reserves, for cultural and recreational needs, and potentially a carbon sink to alleviate greenhouse gas emissions. Inevitably, such functions may conflict with management for production of livestock products. Much of the increasing global demand for meat and milk, particularly from developing countries, will have to be supplied from grassland ecosystems, and this will provide difficult challenges. Increased production of meat and milk generally requires increased intake of metabolizable energy, and thus increased voluntary intake and/or digestibility of diets selected by grazing animals. These will require more widespread and effective application of improved management. Strategies to improve productivity include fertilizer application, grazing management, greater use of crop by-products, legumes and supplements and manipulation of stocking rate and herbage allowance. However, it is often difficult to predict the efficiency and cost-effectiveness of such strategies, particularly in tropical developing country production systems. Evaluation and on-going adjustment of grazing systems require appropriate and reliable assessment criteria, but these are often lacking. A number of emerging technologies may contribute to timely low-cost acquisition of quantitative information to better understand the soil–pasture–animal interactions and animal management in grassland systems. Development of remote imaging of vegetation, global positioning technology, improved diet markers, near IR spectroscopy and modelling provide improved tools for knowledge-based decisions on the productivity constraints of grazing animals. Individual electronic identification of animals offers opportunities for precision management on an individual animal basis for improved productivity. Improved outcomes in the form of livestock products, services and/or other outcomes from grasslands should be possible, but clearly a diversity of solutions are needed for the vast range of environments and social circumstances of global grasslands.

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“…The most relevant is probably the ongoing, 13-year Wambiana grazing trial in Queensland, initiated to specifically test the ability of different grazing strategies to cope with rainfall variability (O'Reagain et al, 2009 and2011). The shorter, 4-year Pigeonhole (PGH; Hunt et al, 2011) and 6-year Mt Sanford (MS; Cowley et al, 2007) trials in the Northern Territory are also important.…”

Section: Insights From Grazing Trialsmentioning

confidence: 99%

Sustainable management for rangelands in a variable climate: evidence and insights from northern Australia

O’Reagain¹,

Scanlan²

2013

Animal

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Inter-annual rainfall variability is a major challenge to sustainable and productive grazing management on rangelands. In Australia, rainfall variability is particularly pronounced and failure to manage appropriately leads to major economic loss and environmental degradation. Recommended strategies to manage sustainably include stocking at long-term carrying capacity (LTCC) or varying stock numbers with forage availability. These strategies are conceptually simple but difficult to implement, given the scale and spatial heterogeneity of grazing properties and the uncertainty of the climate. This paper presents learnings and insights from northern Australia gained from research and modelling on managing for rainfall variability. A method to objectively estimate LTCC in large, heterogeneous paddocks is discussed, and guidelines and tools to tactically adjust stocking rates are presented. The possible use of seasonal climate forecasts (SCF) in management is also considered. Results from a 13-year grazing trial in Queensland show that constant stocking at LTCC was far more profitable and largely maintained land condition compared with heavy stocking (HSR). Variable stocking (VAR) with or without the use of SCF was marginally more profitable, but income variability was greater and land condition poorer than constant stocking at LTCC. Two commercial scale trials in the Northern Territory with breeder cows highlighted the practical difficulties of variable stocking and provided evidence that heavier pasture utilisation rates depress reproductive performance. Simulation modelling across a range of regions in northern Australia also showed a decline in resource condition and profitability under heavy stocking rates. Modelling further suggested that the relative value of variable v. constant stocking depends on stocking rate and land condition. Importantly, variable stocking may possibly allow slightly higher stocking rates without pasture degradation. Enterprise-level simulations run for breeder herds nevertheless show that poor economic performance can occur under constant stocking and even under variable stocking in some circumstances. Modelling and research results both suggest that a form of constrained flexible stocking should be applied to manage for climate variability. Active adaptive management and research will be required as future climate changes make managing for rainfall variability increasingly challenging.Keywords: grazing strategies, profitability, land condition, climate forecasts, simulation models ImplicationsEvidence from northern Australia suggests that managers should apply a form of constrained flexible stocking with upper limits to stocking rate of about 20% to 40% above long-term carrying capacity. Stocking rates should be tactically adjusted on the basis of forage availability, and where appropriate, informed by seasonal climate forecasts. Even in the best years, annual stocking rate increases should be limited to 10% to 20% in order to avoid overstocking in the event of poor subsequent seasons....

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Managing for rainfall variability: effect of grazing strategy on cattle production in a dry tropical savanna

Cited by 63 publications

References 19 publications

Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

Spatial and temporal effects of grazing management and rainfall on the vertebrate fauna of a tropical savanna

The importance of grasslands for animal production and other functions: a review on management and methodological progress in the tropics

Sustainable management for rangelands in a variable climate: evidence and insights from northern Australia

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