%0 Review article
%T A framework for modelling the annual cycle of trees in boreal and temperate regions
%A Hänninen, Heikki
%A Kramer, Koen
%D 2007
%J Silva Fennica
%V 41
%N 1
%R doi:10.14214/sf.313
%U https://silvafennica.fi/article/313
%X Models of the annual development cycle of trees in boreal and temperate  regions were reviewed and classified on the basis of their  ecophysiological assumptions. In our classification we discern two main  categories of tree development: 1) fixed sequence development, which  refers to irreversible ontogenetic development leading to visible  phenological events such as bud burst or flowering, and 2) fluctuating  development, which refers to reversible physiological phenomena such as  the dynamics of frost hardiness during winter. As many of the  physiological phenomena are partially reversible, we also describe  integrated models, which include aspects of both fixed-sequence and  fluctuating development. In our classification we further discern simple  E-models, where the environmental response stays constant, and more  comprehensive ES-models, where the environmental response changes  according to the state of development. On the basis of this model  classification, we have developed an operational modelling framework, in  which we define an explicit state variable and a corresponding rate  variable for each attribute of the annual cycle considered. We introduce  a unifying notation, which we also use when presenting a selection of  previously published models. To illustrate the various developmental  phenomena and their modelling, we have carried out model simulations.  Finally, we discuss the ecophysiological interpretation of the model  variables, methodological aspects of the empirical development and  testing of the models, the introduction of new aspects to the modelling,  other closely related models, and applications of the models.