title: Does seed mass drive the differences in relative growth rate between growth forms?
abstract: The idea that herbaceous plants have higher relative growth rates (RGRs) compared with woody plants is fundamental to many of the most influential theories in plant ecology. This difference in growth rate is thought to reflect systematic variation in physiology, allocation and leaf construction. Previous studies documenting this effect have, however, ignored differences in seed mass. As woody species often have larger seeds and RGR is negatively correlated with seed mass, it is entirely possible the lower RGRs observed in woody species is a consequence of having larger seeds rather than different growth strategies. Using a synthesis of the published literature, we explored the relationship between RGR and growth form, accounting for the effects of seed mass and study-specific effects (e.g. duration of study and pot volume), using a mixed-effects model. The model showed that herbaceous species do indeed have higher RGRs than woody species, and that the difference was independent of seed mass, thus at all seed masses, herbaceous species on average grow faster than woody ones.
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors.forename: Jennie
authors.initials: J
authors.lastname: Houghton
authors.forename: Ken
authors.initials: K
authors.lastname: Thompson
authors.forename: Mark
authors.initials: M
authors.lastname: Rees
mesh_terms: D008954:Models, Biological; D063245:Plant Development; D018521:Plant Physiological Phenomena; D010944:Plants / Q000033:anatomy & histology*; D012639:Seeds / Q000254:growth & development / Q000502:physiology; D013045:Species Specificity
keywords: plant strategies; relative growth rate; seed mass