Late 20th century warming in a coastal horticultural region and its effects on tree phenology

Temperature records (1963–2009) from Alstonville, northern New South Wales, Australia, were examined for long-term trends using two methods: annual smoothing using a sine curve; and temperature-based phenological models applied to different parts of the year. Both methods indicated strong seasonality in warming, with winters increasing by 1.5°C over the period, but summers largely unchanged. Estimates of spring custard apple flower development time decreased by c. 13 days (20%) from 1963/64–2008/09; estimates of autumn litchi flush development decreased by c. 8 days (7%); estimates of winter macadamia flush development decreased by c. 17 days (12%) but summer flush development was not affected; and estimates of mango fruit development decreased by c. 12–16 days (7–8%) depending on variety.