The potential of deep-rooted species to mitigate the impacts of heatwaves and declining rainfall on pastures in Victoria.                                                                                                                      

Scientific journal article

Across Victoria, progressing climate change has seen an increase in temperatures and reductions in spring rainfall. This paper explores one option for reducing the impact of these trends on livestock farms by planting deep-rooted pasture species.

Plants with deep roots have been shown to have better growth and persistence under drought and heat stress conditions. Researchers from the University of Melbourne used whole farm and economic modelling to determine the benefit of sowing pasture grasses with deep roots. Three plants species that differed only in root distribution were modelled at two sites and under two climate change scenarios.

Results suggest that current observed trends of increased pasture production in winter and reductions in spring will continue. If this leads to generally lower pasture supply in spring, increases provided by deep rooted species will have greater value. At the site with a longer growing season, deep rooted species performed better than species with relatively shallow roots. In contrast, the modelling for the site with a shorter growing season did not suggest this: in this case the species with deep roots were not the best option. If the deep-rooted species also had better persistence than the shallow rooted species, it performed better on both sites.

Research on options to reduce impacts of climate change often do not include plant persistence. The economic analysis shows that persistence pays, and it is an important factor to include when evaluating adaptation options. The results also highlight the need to account for local conditions. At dry sites, summer dormancy or increased pasture persistence will likely perform better than increased root depth alone.