biostudies-literatureUnknown64(7)Cuny HEThe intra-annual dynamics of wood formation, which involves the passage of newly produced cells through three successive differentiation phases (division, enlargement, and wall thickening) to reach the final functional mature state, has traditionally been described in conifers as three delayed bell-shaped curves followed by an S-shaped curve. Here the classical view represented by the 'Gompertz function (GF) approach' was challenged using two novel approaches based on parametric generalized linear models (GLMs) and 'data-driven' generalized additive models (GAMs). These three approaches (GFs, GLMs, and GAMs) were used to describe seasonal changes in cell numbers in each of the xylem differentiation phases and to calculate the timing of cell development in three conifer species [Picea abiesJournal of experimental botany1983-94https://www.ebi.ac.uk/biostudies/studies/S-EPMC3638824biostudies-literatureGeneralized additive models reveal the intrinsic complexity of wood formation dynamics.PMC3638824Rathgeber CBFournier MBarbeito IKiesse TSCuny HEHartmann FPfalseGeneralized additive models reveal the intrinsic complexity of wood formation dynamics.The intra-annual dynamics of wood formation, which involves the passage of newly produced cells through three successive differentiation phases (division, enlargement, and wall thickening) to reach the final functional mature state, has traditionally been described in conifers as three delayed bell-shaped curves followed by an S-shaped curve. Here the classical view represented by the 'Gompertz function (GF) approach' was challenged using two novel approaches based on parametric generalized linear models (GLMs) and 'data-driven' generalized additive models (GAMs). These three approaches (GFs, GLMs, and GAMs) were used to describe seasonal changes in cell numbers in each of the xylem differentiation phases and to calculate the timing of cell development in three conifer species [Picea abies2013-01-01T00:00:00Z2013 Apr2025-04-21T23:42:52.121Z2019-03-27T01:08:03ZS-EPMC36388242353013210.1093/jxb/ert057