Climate Change and Variability: Impacts on New Zealand Pastures

Climate change and variability influence the productivity and distribution of New Zealand pasture species. Temperature and rainfall scenarios are used to explore the sensitivity of New Zealand pastures to potential climate warming next century. Temperature affects the length of the growing season with present pasture species extending 200 m higher in altitude for every 1 •c temperature increase. The greater area of New Zealand that becomes frost free allows the spread of subtropical pasture grasses southwards. However, where low rainfall limits pasture production, changes to the rainfall amount have a significant effect. A rainfall change of I 0% changes the duration of pasture growth by about 2 weeks. Rainfall changes are more important in areas of high annual rainfall variability.