Pasture predictions for the Gippsland region are based on the assumption that the pasture system is comprised of predominantly perennial ryegrass and white clover, with some use of short term rye grass.
The predictions suggest that:
The following graph shows predicted pasture growth under three possible scenarios of:
Currently, emissions are tracking the high global emissions scenario and therefore, it is the most relevant for Gippsland. One can assume that something like this high scenario will occur in the absence of major global emission reductions.
The following graphs are expressed as ‘box plots’, which need some explaining in order to be easily understood. The box plot is interpreted as follows:
It is important to note that the predictions are not attempting to describe exactly what will actually happen in the specific year of 2030 or 2070, but indicate a the range pasture production conditions that might be expected at that time in the future, based on the current climate change scenarios.
For Ellinbank, the average pasture production yield in terms of tonnes of dry matter per hectare (t DM/ha) is predicted to increase by approximately 4% for perennial ryegrass/white clover pastures by 2030 under the low emission scenario (and slightly less under high emission scenarios), but substantially decline by up to 23% by 2070 due to shorter spring growth periods.
The following graphs show box-plots of predicted annual pasture production for dryland and irrigated pastures for Ellinbank by 2030 and 2070. The far left plot is the baseline or current situation, while the second, third and fourth plots show predicted pasture yields under low, medium and high climate change scenarios.
The figures below show rainfall, runoff and drainage at Ellinbank. The data are presented for baseline (1971-2000), and the predictions by 2030 and 2070 under the high emissions scenario. As shown, rainfall and drainage are reduced by both 2030 and 2070.
(Hotlink to report: Eckard R, Cullen B, 2008 WFSAT Phase II – Final Report: Whole Farms Systems Analysis and Tools for the Australian and New Zealand Grazing Industries, published by MLA, DA, AgResearch Limited, December.)