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ABSTRACT We analysed records of spring phenological events (budding and flowering) of pear ( Pyrus sp.) cultivar 'Pingguoli' at six sites in the Yanbian District of Jilin Province, northeast China across 58 years from 1953. The aims of this study were to test if the phenological timing in spring has changed due to the long-term change in surface air temperature and to see if the relationship between the phenological timing and the surface air temperature shows nonlinearity as suggested by a past study. We fitted a linear model of phenological timing as the sum of the effects of long-term temperature trends and year-to-year temperature fluctuations. The results showed that the acceleration of spring phenology can be attributed to the corresponding trends of increasing mean air temperature in spring. The relationship between air temperature and phenological timing was linear for budding, but it was nonlinear for flowering with a lower temperature sensitivity at higher air temperature. [ABSTRACT FROM AUTHOR]