Northern Australian agricultural industries are vulnerable to a highly variable climate. Year-to-year fluctuations in rainfall strongly affect pasture growth and increase the challenge of matching forage supply with stock numbers. A case study of climate drivers of pasture growth is conducted for the extensively-grazed cattle enterprises in the semi-arid tropics of north-eastern Australia. By assessing past climate, we explore which aspects of climate variability drive variations in pasture growth to inform effective developments in grazing management tools. Insights gained from these investigations could be important to the understanding of how we might integrate dynamical climate models into the decision making process. Currently, dynamical climate models are limited in their ability to provide skilful 6 month forecasts of total rainfall at the paddock scale. In their favour, we show that variables other than total rainfall are more important in forecasting pasture growth. Predicting total rainfall is dominated by the need to effectively predict the extreme events. We demonstrate that these extreme events do not significantly influence pasture growth as much of the rain received during extreme rainfall events is lost as run-off. A forecast would ideally be able to predict the number of rain days that fall when the soil is dry; incorporate the moisture content of soil at the beginning of the season; determine the likelihood of an early break to the wet season resulting in late winter and/or spring rainfall; and establish the interaction of El Niño Southern Oscillation with other climate modes. We stress however, that potential pasture growth is only one aspect of complex farm management decisions. Optimal decision making must also incorporate factors such as grazing management, cattle condition and longer time horizons as part of a whole of farm approach.

北澳大利亚州的农业产业易受气候变化的影响。降雨的逐年波动极大地影响了牧草的生长，并增加了将牧草供应与种群数量相匹配的挑战。在澳大利亚东北部半干旱热带地区，对广泛放牧的牛企业进行了牧场生长的气候驱动因素案例研究。通过评估过去的气候，我们探索气候变化的哪些方面会驱动牧草生长的变化，从而为放牧管理工具的有效发展提供信息。从这些调查中获得的见解对于理解如何将动态气候模型整合到决策过程中可能非常重要。目前，动态气候模型的能力有限，无法提供围场范围内6个月的降雨量预报。在他们的支持下，我们表明，除总降雨量外，其他变量在预测草场生长方面更为重要。预测总降雨量主要取决于有效预测极端事件的需要。我们证明，这些极端事件不会严重影响草场的生长，因为极端降雨事件期间收到的大部分雨水都随着径流而流失。理想情况下，预测将能够预测土壤干燥时降雨的天数；在季节开始时纳入土壤的水分含量；确定导致冬季晚和/或春季降雨的湿季提前中断的可能性；并建立厄尔尼诺南方涛动与其他气候模式的相互作用。但是，我们强调，潜在的牧场增长只是复杂的农场管理决策的一方面。最佳决策还必须纳入诸如放牧管理，牲畜状况和较长时间范围之类的因素，作为整个农场方法的一部分。