Impacts of environmental feedbacks on the production of a Central Queensland beef enterprise in a future climate

Impacts of environmental feedbacks on the production of a Central Queensland beef enterprise in a future climate

CONTEXT
Understanding climate change impacts on beef production enterprises in northern Australia is challenging due to the complexity of the system, which involves biophysical processes such as pasture and animal production, herd management, economics, emissions, and the interaction among these things. Modelling is a powerful tool to help the beef industry understand the impacts of climate change and to develop adaptation plans to help ensure enterprises remain economically viable over the long term.

OBJECTIVE
We assess climate change impacts on a single specialised beef enterprise south-east of Moura (24.59°S, 150.09°E) in northern Australia's Central Queensland region. This is achieved by comparing enterprise performances during a 2030s climate and a 1975–2013 baseline period.

METHODS
We used a calibrated pasture model called GRASP to simulate the farm's pasture growth under multiple scenarios for land conditions, grass basal areas and stocking rates for the baseline and 2030s climates and to construct pasture growth databases – known as datacubes. The datacubes provide a simplified representation of mean coupling between the herd dynamics and livestock production model (Crop Livestock Enterprise Model). The coupled whole-of-farm model was parameterised using enterprise data collected through interviews with the property owner and allowed for feedback between the pasture and livestock systems. The feedback capability allowed us to consider changes in land condition through stocking rates and their effect on pasture growth, animal weight gain, profit and CO2 emissions.

RESULTS AND CONCLUSIONS
We found that warmer and drier climatic conditions during 2030s will reduce pasture growth in austral spring and summer but increase pasture growth in winter and autumn. Increased pasture growth in winter and autumn cannot compensate for the reduction in pasture growth in the warm seasons but can improve animal liveweight gain in winter and early spring. This leads to an overall increase in annual weight gain of steers (the cattle class that provides the main income source for this farm) while the CO2 emission intensity remains similar to the baseline period. Maintaining land condition under the 2030s climatic conditions considered will require a reduction in sustainable herd size, leading to lower beef production and lower profit under current pasture and herd management strategies. Impacts will likely differ from those described if a drier future is not realised.

SIGNIFICANCE
This study provides a climate change impact assessment on a specialised beef enterprise (i) being distilled from individual ruminants, and (ii) considering environmental feedbacks in the interaction between pasture and livestock systems.