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Despite growing rhetoric regarding the potential benefits of using knowledge brokers in relation toenvironmental challenges and decision-making processes, the evidence in support of such claims ismostly anecdotal. This is, in part, due to the lack of established methods to evaluate the effective-ness and efficiency of knowledge brokers. To address this gap we assess the utility of social networkanalysis (SNA) to evaluate the effectiveness of knowledge brokers in connecting scientists anddecision-makers. Specifically, using a case-study approach, we undertake longitudinal SNA overa 12-month period to evaluate the extent to which the knowledge broker developed networks be-tween producers and users of knowledge across different organizations. We also undertook a qual-itative survey of scientists (n = 29) who worked in the same organization as the knowledge broker tounderstand the extent to which the knowledge broker increased the impact of scientific researchfor decision-making purposes. Results show that the knowledge broker developed an extensivestakeholder network of 192 individuals spanning over 30 organizations. The results of the SNAfound that over time this network increased in density and became more cohesive, both key ele-ments underpinning successful knowledge exchange. Furthermore, the qualitative survey foundthat the knowledge broker also had a positive impact in other ways, including helping researchersunderstand the operating environments within decision-making agencies and the best approachesfor engaging with specific decision-makers. Thus, this study demonstrates the value of SNA forevaluating knowledge brokers and provides empirical support for the use of knowledge brokersin the environmental sector.

Grazing is a major land use in Australia's rangelands. The 'safe' livestock carrying capacity (LCC) required to maintain resource condition is strongly dependent on climate. We reviewed: the approaches for quantifying LCC; current trends in climate and their effect on components of the grazing system; implications of the 'best estimates' of climate change projections for LCC; the agreement and disagreement between the current trends and projections; and the adequacy of current models of forage production in simulating the impact of climate change. We report the results of a sensitivity study of climate change impacts on forage production across the rangelands, and we discuss the more general issues facing grazing enterprises associated with climate change, such as 'known uncertainties' and adaptation responses (e.g. use of climate risk assessment). We found that the method of quantifying LCC from a combination of estimates (simulations) of long-term (>30 years) forage production and successful grazier experience has been well tested across northern Australian rangelands with different climatic regions. This methodology provides a sound base for the assessment of climate change impacts, even though there are many identified gaps in knowledge. The evaluation of current trends indicated substantial differences in the trends of annual rainfall (and simulated forage production) across Australian rangelands with general increases in most of western Australian rangelands ( including northern regions of the Northern Territory) and decreases in eastern Australian rangelands and south-western Western Australia. Some of the projected changes in rainfall and temperature appear small compared with year-to-year variability. Nevertheless, the impacts on rangeland production systems are expected to be important in terms of required managerial and enterprise adaptations. Some important aspects of climate systems science remain unresolved, and we suggest that a risk-averse approach t

The strong trends in climate change already evident, the likelihood of further changes occurring, and the increasing scale of potential climate impacts give urgency to addressing agricultural adaptation more coherently. There are many potential adaptation options available for marginal change of existing agricultural systems, often variations of existing climate risk management. We show that implementation of these options is likely to have substantial benefits under moderate climate change for some cropping systems. However, there are limits to their effectiveness under more severe climate changes. Hence, more systemic changes in resource allocation need to be considered, such as targeted diversification of production systems and livelihoods. We argue that achieving increased adaptation action will necessitate integration of climate change-related issues with other risk factors, such as climate variability and market risk, and with other policy domains, such as sustainable development. Dealing with the many barriers to effective adaptation will require a comprehensive and dynamic policy approach covering a range of scales and issues, for example, from the understanding by farmers of change in risk profiles to the establishment of efficient markets that facilitate response strategies. Science, too, has to adapt. Multidisciplinary problems require multidisciplinary solutions, i.e., a focus on integrated rather than disciplinary science and a strengthening of the interface with decision makers. A crucial component of this approach is the implementation of adaptation assessment frameworks that are relevant, robust, and easily operated by all stakeholders, practitioners, policymakers, and scientists.

We review recent research of importance to understanding crop and pasture plant species response to climate change. Topics include plant response to elevated CO2 concentration, interactions with climate change variables and air pollutants, impacts of increased climate variability and frequency of extreme events, the role of weeds and pests, disease and animal health, issues in biodiversity, and vulnerability of soil carbon pools. We critically analyze the links between fundamental knowledge at the plant and plot level and the additional socio-economic variables that determine actual production and trade of food at regional to global scales. We conclude by making recommendations for current and future research needs, with a focus on continued and improved integration of experimental and modeling efforts.

Recent conclusions that new free-air carbon dioxide enrichment (FACE) data show a much lower crop yield response to elevated CO2 than thought previously - casting serious doubts on estimates of world food supply in the 21st century - are found to be incorrect, being based in part on technical inconsistencies and lacking statistical significance. First, we show that the magnitude of crop response to elevated CO2 is rather similar across FACE and non-FACE data-sets, as already indicated by several previous comprehensive experimental and modeling analyses, with some differences related to which "ambient" CO2 concentration is used for comparisons. Second, we find that results from most crop model simulations are consistent with the values from FACE experiments. Third, we argue that lower crop responses to elevated CO2 of the magnitudes in question would not significantly alter projections of world food supply. We conclude by highlighting the importance of a better understanding of crop response to elevated CO2 under a variety of experimental and modeling settings, and suggest steps necessary to avoid confusion in future meta-analyses and comparisons of experimental and model data.

This study outlines the development of an approach to evaluate the sources, sinks, and magnitudes of greenhouse gas emissions from a grazed semiarid rangeland dominated by mulga (Acacia aneura) and how these emissions may be altered by changes in management. This paper describes the modification of an existing pasture production model (GRASP) to include a gas emission component and a dynamic tree growth and population model. An exploratory study was completed to investigate the likely impact of changes in burning practices and stock management on emissions. This study indicates that there is a fundamental conflict between maintaining agricultural productivity and reducing greenhouse gas emissions on a given unit of land. Greater agricultural productivity is allied with the system being an emissions source while production declines and the system becomes a net emissions sink as mulga density increases. Effective management for sheep production results in the system acting as a net source (∼60–200 kg CO2 equivalents/ha/year). The magnitude of the source depends on the management strategies used to maintain the productivity of the system and is largely determined by starting density and average density of the mulga over the simulation period. Prior to European settlement, it is believed that the mulga lands were burnt almost annually. Simulations indicate that such a management approach results in the system acting as a small net sink with an average net absorption of greenhouse gases of 14 kg CO2 equivalents/ha/year through minimal growth of mulga stands. In contrast, the suppression of fire and the introduction of grazing results in thickening of mulga stands and the system can act as a significant net sink absorbing an average of 1000 kg CO2 equivalents/ha/year. Although dense mulga will render the land largely useless for grazing, land in this region is relatively inexpensive and could possibly be developed as a cost-effective carbon offset for greenhouse gas emiss

Emerald, north-east Queensland, is at the northern margin of the wheat cropping region of Australia. The Emerald region was previously used predominantly for grazing beef cattle, however, cropping has developed in importance over the past 30 years. We use historical climate records (1890–1998) to simulate and compare wheat yields, grass production and liveweight gain (LWG) over time. The cropping expansion from the 1970s to the early 1990s has occurred in a unique period in the 108-year record with the highest average wheat yields, lowest wheat yield variability and the greatest relative productivity of wheat production against grass production. If this window of opportunity is a result of long-term climate variability, then cropping is likely to decline in the region as conditions return to those experienced earlier in the record. If this increase is related to climate change, then cropping is likely to persist in the region with productivity maintained at current levels particularly through the yield-enhancing effects of increased atmospheric CO2 concentrations. However, this persistence will be influenced by the frequencies of El Niño conditions which may increase with global warming. The high relative productivities experienced over the past few decades have probably biased producers, expectations, and applications for drought support need to take into account the longer-term perspective provided by this analysis. Nevertheless, the last six years have the lowest simulated mean LWG production on the record. The identification of poor production periods depended on the production element being addressed and the timescale involved.

The wheat module, I_WHEAT, from the APSIM cropping system model was used to investigate the impacts of changes in atmospheric CO2 concentrations on wheat crops by modifying radiation use efficiency, transpiration efficiency, specific leaf area and critical nitrogen concentrations. The effects of several combinations of atmospheric CO2, climate change and crop adaptation strategies on wheat production in the Burnett region were studied. Mean wheat yields were increased under doubled CO2, with the response relative to ambient CO2 greatest in dry years. Higher temperatures under the climate change scenarios moderated the yield gains achieved with increasing CO2 and in some instances reversed them under the reduced rainfall scenario. The status of the region as a producer of prime hard wheat may be at risk due to reduced grain protein levels under doubled CO2 and the increased likelihood of “heat shock” in the climate scenarios used.

The 160 million ha of grazing land in Queensland support approximately 10 million beef equivalents (9.8 million cattle and 10.7 million sheep) with treed and cleared native pastures as the major forage source. The complexity of these biophysical systems and their interaction with pasture and stock management, economic and social forces limits our ability to easily calculate the impact of climate change scenarios. We report the application of a systems approach in simulating the flow of plant dry matter and utilisation of forage by animals. Our review of available models highlighted the lack of suitable mechanistic models and the potential role of simple empirical relationships of utilisation and animal production derived from climatic and soil indices. Plausible climate change scenarios were evaluated by using a factorial of rainfall (f 10%) * 3260C temperature increase * doubling CO, in sensitivity studies at property, regional and State scales. Simulation of beef cattle liveweight gain at three locations in the Queensland black speargrass zone showed that a *lo% change in rainfall was magnified to be a f 15% change in animal production (liveweight gain per ha) depending on location, temperature and CO, change. Models of 'safe' carrying capacity were developed from property data and expert opinion. Climate change impacts on 'safe' carrying capacity varied considerably across the State depending on whether moisture, temperature or nutrients were the limiting factors. Without the effect of doubling CO,, warmer temperatures and +lo% changes in rainfall resulted in -35 to +70% changes in 'safe' carrying capacity depending on location. With the effect of doubling CO, included, the changes in 'safe' carrying capacity ranged from -12 to +115% across scenarios and locations. When aggregated to a whole-of-State carrying capacity, the combined effects of warmer temperature, doubling CO, and +lo% changes in rainfall resulted in 'safe' carrying capacity changes of +3 to +45% d

Climate change is an important global issue but is yet to be recognised as such by many rangelands users. This paper reviews some of the uncertainties relating to pre-instrumental and future climate change and documents current trends and fluctuations in climate of Queensland's grazing lands. Analysis of daily climate surfaces for Queensland's pastoral/cropping zone shows high variability in annual rainfall which is influenced by the El NiHo-Southern Oscillation (ENSO) phenomenon. This relationship, when examined using moving windows, has changed during this century with the 1930-40s being a period of low correlation. Minimum temperatures taken from the climate surfaces also changed, showing a significant (P<0.01) increase over time especially in May. Over the 40 years since 1957, annual minimum temperatures have increased by l.0°C for the pastoral/cropping zone and coastal sub-zone, winter minimum temperatures by 1.2°C for the pastoral/cropping zone (1.3°C for the coastal sub-zone), summer minimum temperatures by 0.7°C for the pastoral/cropping zone and coastal sub-zone, and May minimum temperatures by 2.8°C for the pastoral/cropping zone (3.0°C for the coastal sub-zone). Consistent significant trends in vapour pressure (increasing, P<0.001) and solar radiation (decreasing, P<0.05) also occurred in May. The mechanisms for the identified climate trends and unusual behaviour of ENS0 are the subject of speculation with attribution of causes to natural variability or the enhanced greenhouse effect being unresolved. Continued monitoring of these trends and fluctuations will be important for the future management of Queensland's grazing lands with this analysis highlighting the need for discrimination of trends from natural variability. In terms of grazing management and degradation processes, this work also highlights that general changes in climate averages may disguise important variation at yearly and decadal time scales.