title: Size symmetry of competition alters biomass-density relationships.
abstract: As crowded populations of plants develop, the growth of some plants is accompanied by the death of others, a process called density-dependent mortality or 'self-thinning'. During the course of density-dependent mortality, the relationship between total population biomass (B) and surviving plant density (N) is allometric: B = aN(b). Essentially, increasing population biomass can be achieved only through decreasing population density. Variation in the allometric coefficient a among species has been recognized for many years and is important for management, assessment of productivity and carbon budgets, but the causes of this variation have not been elucidated. Individual-based models predict that size-dependent competition causes variation in the allometric coefficient. Using transgenic Arabidopsis with decreased plasticity, we provide experimental evidence that morphological plasticity of wild-type populations decreases the size asymmetry of competition for light and thereby decreases density-dependent mortality. This decrease in density-dependent mortality results in more biomass at a given density under size-symmetric compared with size-asymmetric competition.
authors.affiliation: Institute for Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland. peter.stoll@unibas.ch
authors.forename: Peter
authors.initials: P
authors.lastname: Stoll
authors.forename: Jacob
authors.initials: J
authors.lastname: Weiner
authors.forename: Helene
authors.initials: H
authors.lastname: Muller-Landau
authors.forename: Elke
authors.initials: E
authors.lastname: Müller
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Hara
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development; D018533:Biomass; D017753:Ecosystem; D008954:Models, Biological; D015233:Models, Statistical; D063245:Plant Development; D010944:Plants / Q000033:anatomy & histology*; D030821:Plants, Genetically Modified; D011156:Population Density