The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Default user image.

Anna Maria Jönsson


Default user image.

Performance of tree phenology models along a bioclimatic gradient in Sweden


  • Cecilia Olsson
  • Kjell Bolmgren
  • Johan Lindström
  • Anna Maria Jönsson

Summary, in English

Tree phenology has been recognized as an important indicator of climate change, and a wide range of budburst models have been developed. The models differ in temperature sensitivity, and the choice of model can therefore influence the result of climate impact assessments. In this study we compared the ability of 15 models to simulate budburst of the main forest tree species in Sweden. Records on the timing of budburst, available for 1873-1918 and 1966-2011, were used for model evaluation. The predefined models, having different chilling, competence and forcing modules, represented different hypothesis on temperature impact on tree phenology. We extracted the model-specific forcing units accumulated by the observed day of budburst, and tested for covariation with bio-climatic gradients. For all tree species, most models indicated a negative relation between forcing requirement and latitude, which may indicate provenance specific adaptations. The thermal continentality index, which in Sweden is highly correlated with latitude, did provide some additional explanation for the period of 1873-1918 but not for the period of 1966-2011. For most model- and tree species combinations, temperature anomalies explain a significant part of the variability in forcing units accumulated at day of budburst. This indicates that the budburst models were not able to fully track the response to inter-annual variations in temperature conditions, probably due to difficulties in capturing species and provenance specific chilling requirement, day length response and impact of spring backlashes. (C) 2013 Elsevier B.V. All rights reserved.


  • Dept of Physical Geography and Ecosystem Science
  • Mathematical Statistics
  • MERGE: ModElling the Regional and Global Earth system
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year







Ecological Modelling



Document type

Journal article




  • Probability Theory and Statistics
  • Physical Geography


  • Tree phenology
  • Budburst model
  • Temperature sums
  • Forcing units




  • ISSN: 0304-3800