Resting Subtropical Grasslands from Grazing in the Wet Season Boosts Biocrust Hotspots to Improve Soil Health

Effective grazing management in Australia’s semi-arid rangelands requires monitoring landscape conditions and identifying sustainable and productive practice through understanding the interactions of environmental factors and management of soil health. Challenges include extreme rainfall variability, intensifying drought, and inherently nutrient-poor soils. We investigated the impacts of grazing strategies on landscape function—specifically soil health—as the foundation for productive pastures, integrating the heterogenous nature of grass tussocks and the interspaces that naturally exist in between them. At Wambiana—a long-term research site in north-eastern Australia—we studied two soil types, two stocking rates (high, moderate), and resting land from grazing during wet seasons (rotational spelling). Rotational spelling had the highest biocrust (living soil cover), in interspaces and under grass tussocks. Biocrusts were dominated by cyanobacteria that binds soil particles, reduces erosion, sequesters carbon, fixes nitrogen, and improves soil fertility. Rotational spelling with a moderate stocking rate emerged as best practice at these sites, with adjustment of stocking rates in line with rainfall and soil type recommended. In drought-prone environments, monitoring the presence and integrity of biocrusts connects landscape function and soil health. Biocrusts that protect and enrich the soil will support long-term ecosystem integrity and economic profitability of cattle production in rangelands.

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

Animal Production Science ◽

10.1071/ea07187 ◽

2009 ◽

Vol 49 (2) ◽

pp. 85 ◽

Cited By ~ 47

Author(s):

Peter O'Reagain ◽

John Bushell ◽

Chris Holloway ◽

Angela Reid

Keyword(s):

Southern Oscillation ◽

Rainfall Variability ◽

Cattle Production ◽

Long Term Effects ◽

Seasonal Forecasts ◽

Wet Season ◽

Variable Environment ◽

Condition Score ◽

Stocking Rates

Rainfall variability is a challenge to sustainable and profitable cattle production in northern Australia. Strategies recommended to manage for rainfall variability, like light or variable stocking, are not widely adopted. This is due partly to the perception that sustainability and profitability are incompatible. A large, long-term grazing trial was initiated in 1997 in north Queensland, Australia, to test the effect of different grazing strategies on cattle production. These strategies are: (i) constant light stocking (LSR) at long-term carrying capacity (LTCC); (ii) constant heavy stocking (HSR) at twice LTCC; (iii) rotational wet-season spelling (R/Spell) at 1.5 LTCC; (iv) variable stocking (VAR), with stocking rates adjusted in May based on available pasture; and (v) a Southern Oscillation Index (SOI) variable strategy, with stocking rates adjusted in November, based on available pasture and SOI seasonal forecasts. Animal performance varied markedly over the 10 years for which data is presented, due to pronounced differences in rainfall and pasture availability. Nonetheless, lighter stocking at or about LTCC consistently gave the best individual liveweight gain (LWG), condition score and skeletal growth; mean LWG per annum was thus highest in the LSR (113 kg), intermediate in the R/Spell (104 kg) and lowest in the HSR (86 kg). Mean LWG was 106 kg in the VAR and 103 kg in the SOI but, in all years, the relative performance of these strategies was dependent upon the stocking rate applied. After 2 years on the trial, steers from lightly stocked strategies were 60–100 kg heavier and received appreciable carcass price premiums at the meatworks compared to those under heavy stocking. In contrast, LWG per unit area was greatest at stocking rates of about twice LTCC; mean LWG/ha was thus greatest in the HSR (21 kg/ha), but this strategy required drought feeding in four of the 10 years and was unsustainable. Although LWG/ha was lower in the LSR (mean 14 kg/ha), or in strategies that reduced stocking rates in dry years like the VAR (mean 18 kg/ha) and SOI (mean 17 kg/ha), these strategies did not require drought feeding and appeared sustainable. The R/Spell strategy (mean 104 kg/ha) was compromised by an ill-timed fire, but also performed satisfactorily. The present results provide important evidence challenging the assumption that sustainable management in a variable environment is unprofitable. Further research is required to fully quantify the long-term effects of these strategies on land condition and profitability and to extrapolate the results to breeder performance at the property level.

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Extreme rainfall deficits were not the cause of recurring colonial era famines of southern Indian semi-arid regions

Scientific Reports ◽

10.1038/s41598-021-96826-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ranjini Ray ◽

Atreyee Bhattacharya ◽

Gaurav Arora ◽

Kushank Bajaj ◽

Keyle Horton ◽

...

Keyword(s):

Arid Regions ◽

Human Impacts ◽

Rainfall Variability ◽

Extreme Rainfall ◽

Southern India ◽

Colonial Era ◽

Regional Rainfall ◽

Semi Arid ◽

Rainfall Deficits

AbstractUsing information contained in the eighteenth to twentieth century British administrative documents, preserved in the National Archives of India (NAI), we present a 218-year (1729–1947 AD) record of socioeconomic disruptions and human impacts (famines) associated with ‘rain failures’ that affected the semi-arid regions (SARs) of southern India. By mapping the southern Indian famine record onto long-term spatiotemporal measures of regional rainfall variability, we demonstrate that the SARs of southern India repeatedly experienced famines when annual rainfall reduced by ~ one standard deviation (1 SD), or more, from long-term averages. In other words, ‘rain failures’ listed in the colonial documents as causes of extreme socioeconomic disruptions, food shortages and human distress (famines) in the southern Indian SARs were fluctuations in precipitation well within the normal range of regional rainfall variability and not extreme rainfall deficits (≥ 3 SD). Our study demonstrates that extreme climate events were not necessary conditions for extreme socioeconomic disruptions and human impacts rendered by the colonial era famines in peninsular India. Based on our findings, we suggest that climate change risk assessement should consider the potential impacts of more frequent low-level anomalies (e.g. 1 SD) in drought prone semi-arid regions.

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Restoring Farm Woodlands for Wildlife

10.1071/9781486309658 ◽

2018 ◽

Cited By ~ 1

Author(s):

David Lindenmayer ◽

Damian Michael ◽

Mason Crane ◽

Daniel Florance ◽

Emma Burns

Keyword(s):

Natural Resource Management ◽

Best Practice ◽

Animal Species ◽

Agricultural Landscapes ◽

Native Plant ◽

Policy Makers ◽

Eastern Australia ◽

Farm Woodlands ◽

Grazing Livestock

Millions of hectares of temperate woodland and billions of trees have been cleared from Australia’s agricultural landscapes. This has allowed land to be developed for cropping and grazing livestock but has also had significant environmental impacts, including erosion, salinity and loss of native plant and animal species. Restoring Farm Woodlands for Wildlife focuses on why restoration is important and describes best practice approaches to restore farm woodlands for birds, mammals and reptiles. Based on 19 years of long-term research in temperate agricultural south-eastern Australia, this book addresses practical questions such as what, where and how much to plant, ways to manage plantings and how plantings change over time. It will be a key reference for farmers, natural resource management professionals and policy-makers concerned with revegetation and conservation.

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Sustainable grazing management for temporal and spatial variability in north Australian rangelands – a synthesis of the latest evidence and recommendations

The Rangeland Journal ◽

10.1071/rj13110 ◽

2014 ◽

Vol 36 (3) ◽

pp. 223 ◽

Cited By ~ 30

Author(s):

Peter O'Reagain ◽

Joe Scanlan ◽

Leigh Hunt ◽

Robyn Cowley ◽

Dionne Walsh

Keyword(s):

Key Management ◽

Rainfall Variability ◽

Grazing Management ◽

Economic Modelling ◽

Infrastructure Development ◽

Northern Australia ◽

Wet Season ◽

Sustainable Grazing ◽

Patch Burning

Rainfall variability is a major challenge to sustainable grazing management in northern Australia, with management often complicated further by large, spatially-heterogeneous paddocks. This paper presents the latest grazing research and associated bio-economic modelling from northern Australia and assesses the extent to which current recommendations to manage for these issues are supported. Overall, stocking around the safe long-term carrying capacity will maintain land condition and maximise long-term profitability. However, stocking rates should be varied in a risk-averse manner as pasture availability varies between years. Periodic wet-season spelling is also essential to maintain pasture condition and allow recovery of overgrazed areas. Uneven grazing distributions can be partially managed through fencing, providing additional water-points and in some cases patch-burning, although the economics of infrastructure development are extremely context-dependent. Overall, complex multi-paddock grazing systems do not appear justified in northern Australia. Provided the key management principles outlined above are applied in an active, adaptive manner, acceptable economic and environmental outcomes will be achieved irrespective of the grazing system applied.

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Optimal management of fertiliser and stocking rate in temperate grazing systems

Animal Production Science ◽

10.1071/an09067 ◽

2010 ◽

Vol 50 (1) ◽

pp. 6 ◽

Cited By ~ 9

Author(s):

Karel Mokany ◽

Andrew D. Moore ◽

Phillip Graham ◽

Richard J. Simpson

Keyword(s):

Cash Flow ◽

Application Rate ◽

Optimal Management ◽

Stocking Rate ◽

Eastern Australia ◽

Grazing Systems ◽

Fertiliser Application ◽

Gross Margins ◽

Stocking Rates

Phosphorus (P) fertilisers are one of the key tools available for increasing pasture production and the profitability of grazing enterprises. However, recent rapid changes in fertiliser price have increased the importance of developing optimal management strategies for applying P fertiliser and setting stocking rates. We applied a novel combination of process-based grazing systems modelling and randomised cash flow analyses to examine how changes in fertiliser price affect optimal fertiliser application rates and stocking rates for sheep grazing systems in south-eastern Australia, simultaneously taking into account long-term economic viability and environmental sustainability. We used ‘GrassGro’, a grazing systems decision support tool, to simulate three sheep enterprise types (Merino wethers, Merino ewes, crossbred ewes) at two locations (Hamilton, Victoria; Bookham, New South Wales). Gross margins from each year simulated in GrassGro (1966–2007) were randomised 500 times and input to a cash flow analysis that identified the financially optimal stocking rate for a range of fertiliser applications and the financial risk frontiers (combinations of stocking rate and fertiliser input for which the enterprise becomes financially unviable). For all enterprises examined at both locations, the optimal combinations of stocking rate and fertiliser application rate did not vary markedly as fertiliser price changed. Regardless of enterprise type or location, the fertiliser application rate at which the highest gross margins were achieved provided the greatest range of stocking rates that were both financially viable and environmentally sustainable. Increases in fertiliser price reduced the combinations of stocking rate and fertiliser application rate that were viable in the long term, emphasising the importance of well informed grazing management decisions.

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Improvement in soil structure resulting from sown pastures on degraded areas in the dry savanna woodlands of northern Australia

Soil Research ◽

10.1071/sr9830083 ◽

1983 ◽

Vol 21 (1) ◽

pp. 83 ◽

Cited By ~ 7

Author(s):

BJ Bridge ◽

JJ Mott ◽

WH Winter ◽

RJ Hartigan

Keyword(s):

Soil Structure ◽

Surface Soil ◽

Northern Australia ◽

Wet Season ◽

Stylosanthes Hamata ◽

Native Grassland ◽

Townsville Stylo ◽

Stocking Rates ◽

High Infiltration

The structure of the surface soil under pastures sown on a former Themada australis native grassland and on degraded areas in the red earths of northern Australia was examined micromorphologically. Heavily grazed pastures containing the legumes Stylosanthes hamata cv. Verano and Alysicarpus vaginalis had more macropore space in the surface soil than arlightly grazed native grassland, while pastures containing S. humilis (Townsville stylo) had as little macropore space as degraded areas. Macropore space in a S. hamata pasture increased between the third and fourth wet seasons after establishment. Where macropore space was high, infiltration measurements showed that sorptivities were as high as those in the native grassland. Where macropore space was low, sorptivities were as low as those in degraded areas. However, all sown pastures showed low hydraulic conductivities equivalent to those in the degraded areas, and this was attributed to trampling during the wet season under the higher stocking rates involved. The improvement and maintenance of soil structure in the S. hamata and A. vaginalis pastures, together with their high sorptivities, indicates that they are stable in the long term.

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On the Remote Drivers of Rainfall Variability in Australia

Monthly Weather Review ◽

10.1175/2009mwr2861.1 ◽

2009 ◽

Vol 137 (10) ◽

pp. 3233-3253 ◽

Cited By ~ 426

Author(s):

James S. Risbey ◽

Michael J. Pook ◽

Peter C. McIntosh ◽

Matthew C. Wheeler ◽

Harry H. Hendon

Keyword(s):

Large Scale ◽

Decadal Variability ◽

Southern Oscillation ◽

Rainfall Variability ◽

Southern Annular Mode ◽

Wet Season ◽

The North ◽

Eastern Australia ◽

Different Seasons ◽

The Individual

Abstract This work identifies and documents a suite of large-scale drivers of rainfall variability in the Australian region. The key driver in terms of broad influence and impact on rainfall is the El Niño–Southern Oscillation (ENSO). ENSO is related to rainfall over much of the continent at different times, particularly in the north and east, with the regions of influence shifting with the seasons. The Indian Ocean dipole (IOD) is particularly important in the June–October period, which spans much of the wet season in the southwest and southeast where IOD has an influence. ENSO interacts with the IOD in this period such that their separate regions of influence cover the entire continent. Atmospheric blocking also becomes most important during this period and has an influence on rainfall across the southern half of the continent. The Madden–Julian oscillation can influence rainfall in different parts of the continent in different seasons, but its impact is strongest on the monsoonal rains in the north. The influence of the southern annular mode is mostly confined to the southwest and southeast of the continent. The patterns of rainfall relationship to each of the drivers exhibit substantial decadal variability, though the characteristic regions described above do not change markedly. The relationships between large-scale drivers and rainfall are robust to the selection of typical indices used to represent the drivers. In most regions the individual drivers account for less than 20% of monthly rainfall variability, though the drivers relate to a predictable component of this variability. The amount of rainfall variance explained by individual drivers is highest in eastern Australia and in spring, where it approaches 50% in association with ENSO and blocking.

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Climate suitability estimates offer insight into fundamental revegetation challenges among post-mining rehabilitated landscapes in eastern Australia

Biogeosciences Discussions ◽

10.5194/bgd-9-18545-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 18545-18569 ◽

Cited By ~ 6

Author(s):

P. Audet ◽

S. Arnold ◽

A. M. Lechner ◽

D. R. Mulligan ◽

T. Baumgartl

Keyword(s):

Rainfall Variability ◽

Climate Data ◽

Environmental Challenges ◽

Mining Sites ◽

Key Characteristics ◽

Eastern Australia ◽

Ecological Development ◽

Climate Suitability ◽

Short And Long Term

Abstract. Rehabilitation of post-mining sites in semi-arid/subtropical environments of eastern Australia have a general objective to establish specific types of native vegetation communities as defined in mine closure plans and in relation to the specific biotic and abiotic requirements of such communities. Critical for the success of rehabilitation is the availability of water and hence the climatic characteristic of this geographical region which is defined by a number of weather-bound factors (e.g. potentially erratic rainfall and periods of drought and flooding). However, specific estimates of climate suitability are seldom incorporated into current mined land rehabilitation design. To address this, our analysis combined various broad-scale climatic parameters (i.e. primarily relating to rainfall) to assess bioregional suitability-susceptibility within the context of plant early-establishment in the objective of informing rehabilitation schemes as to the inherent environmental challenges influencing both short- and long-term ecological development. Following our survey of available climate data, we derived site suitability-susceptibility indexes (that are otherwise currently not available within rehabilitation schemes) and compared the performance of 9 mine site locations in which our Centre has been engaged in environmental monitoring (Weipa, Mt. Isa, Ernest Henry, Eromanga, Kidston, Curragh, Tarong, North Stradbroke Island, and Newnes Plateau). More specifically, the sites were ranked from most-to-least suitable and compared with natural vegetation patterns (as estimated by the mean NDVI). Overall, it was determined that regular rainfall and relatively short periods of water-deficit are key characteristics of climate suitability (as found among the relatively more temperate coastal-hinterland sites), whereas high rainfall variability and (or) prolonged seasonal drought are primary characteristics of unsuitability (as found among the arid central-inland sites). Conceptual and practical considerations are provided which could inform rehabilitation schemes as to the inherent environmental challenges influencing both short- and long-term ecological development.

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Comparing fixed and flexible stocking as adaptations to inter-annual rainfall variability in the extensive beef industry of northern Australia

The Rangeland Journal ◽

10.1071/rj15045 ◽

2016 ◽

Vol 38 (1) ◽

pp. 85 ◽

Cited By ~ 4

Author(s):

Lester Pahl ◽

Joe Scanlan ◽

Giselle Whish ◽

Robyn Cowley ◽

Neil MacLeod

Keyword(s):

Carrying Capacity ◽

Rainfall Variability ◽

Full Range ◽

Herd Size ◽

Annual Rainfall ◽

Northern Australia ◽

Beef Industry ◽

Growing Seasons ◽

Stocking Rates

Many beef producers within the extensive cattle industry of northern Australia attempt to maintain a constant herd size from year-to-year (fixed stocking), whereas others adjust stock numbers to varying degrees annually in response to changes in forage supply. The effects of these strategies on pasture condition and cattle productivity cannot easily be assessed by grazing trials. Simulation studies, which include feedbacks of changes to pasture condition on cattle liveweight gain, can extend the results of grazing trials both spatially and temporally. They can compare a large number of strategies, over long periods of time, for a range of climate periods, at locations which differ markedly in climate. This simulation study compared the pasture condition and cattle productivity achieved by fixed stocking at the long-term carrying capacity with that of 55 flexible stocking strategies at 28 locations across Queensland and the Northern Territory. Flexible stocking strategies differed markedly in the degree they increased or decreased cattle stocking rates after good and poor pasture growing seasons, respectively. The 28 locations covered the full range in average annual rainfall and inter-annual rainfall variability experienced across northern Australia. Constrained flexibility, which limited increases in stocking rates after good growing seasons to 10% but decreased them by up to 20% after poor growing seasons, provides sustainable productivity gains for cattle producers in northern Australia. This strategy can improve pasture condition and increase cattle productivity relative to fixed stocking at the long-term carrying capacity, and its capacity to do this was greatest in the semiarid rangeland regions that contain the majority of beef cattle in northern Australia. More flexible stocking strategies, which also increased stocking rates after good growing seasons by only half as much as they decreased them after poor growing seasons, were equally sustainable and more productive than constrained flexibility, but are often impractical at property and industry scales. Strategies with the highest limits (e.g. 70%) for both annual increases and decreases in stocking rates could achieve higher cattle productivity, but this was at the expense of pasture condition and was not sustainable. Constrained flexible stocking, with a 10% limit for increases and a 20% limit for decreases in stocking rates annually, is a risk-averse adaptation to high and unpredictable rainfall variability for the extensive beef industry of northern Australia.

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Managing for rainfall variability: long-term profitability of different grazing strategies in a northern Australian tropical savanna

Animal Production Science ◽

10.1071/an10106 ◽

2011 ◽

Vol 51 (3) ◽

pp. 210 ◽

Cited By ~ 54

Author(s):

Peter O'Reagain ◽

John Bushell ◽

Bill Holmes

Keyword(s):

Sustainable Management ◽

Southern Oscillation ◽

Rainfall Variability ◽

Seasonal Forecasts ◽

Variable Environment ◽

Poor Condition ◽

Product Value ◽

Grazing Strategies ◽

Stocking Rates

Several grazing strategies are recommended to manage sustainably for rainfall variability in northern Australia, but there is little objective data on their profitability relative to less sustainable management systems such as heavy stocking. In 1997, a large cattle grazing trial was initiated in northern Queensland to quantify the relative performance of a range of grazing strategies in a variable climate. These strategies were (i) moderate stocking (MSR) stocked at the calculated long-term carrying capacity (LTCC), (ii) heavy stocking (HSR) at twice LTCC, (iii) rotational wet-season spelling (R/Spell) at 1.5 LTCC, (iv) variable stocking (VAR), with stocking rates adjusted in May based on available forage and (v) a southern oscillation index (SOI)-variable strategy, with stocking rates adjusted in November based on available forage and SOI-based seasonal forecasts. Rainfall varied over the 12-year trial period, with sequences of dry and wet years. Gross margins (GM) in the HSR were initially high but collapsed in drier years due to high costs and reduced product value. GMs only recovered in later years with a reduced stocking rate and increased rainfall. The VAR and SOI were also initially very profitable, but GMs plunged as rainfall declined due to reduced animal performance and the sale of poor-condition cattle. This sharp cut in stocking rates nevertheless allowed GMs to recover well in subsequent years. In the MSR, GMs remained relatively constant across most years due to low costs and a higher product value. The R/Spell also performed relatively well despite being compromised by an ill-timed fire, drought and the subsequent sale of poor-condition cattle. Net present value (NPV) after 12 years was highest in the VAR ($11 962/100 ha), followed by the MSR ($11 873/100 ha), the SOI ($11 167/100 ha) and the R/Spell ($10 665/100 ha). NPV was by far the lowest in the HSR ($6930/100 ha). Profitability also varied the most in the HSR, with a negative GM in 6 of the 12 years. Incorporating the costs of natural resource decline would further reinforce the case against heavy stocking. These results challenge the assumption that sustainable management in a variable environment is unprofitable.

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