title: Asymmetric competition causes multimodal size distributions in spatially structured populations.
abstract: Plant sizes within populations often exhibit multimodal distributions, even when all individuals are the same age and have experienced identical conditions. To establish the causes of this, we created an individual-based model simulating the growth of trees in a spatially explicit framework, which was parametrized using data from a long-term study of forest stands in New Zealand. First, we demonstrate that asymmetric resource competition is a necessary condition for the formation of multimodal size distributions within cohorts. By contrast, the legacy of small-scale clustering during recruitment is transient and quickly overwhelmed by density-dependent mortality. Complex multi-layered size distributions are generated when established individuals are restricted in the spatial domain within which they can capture resources. The number of modes reveals the effective number of direct competitors, while the separation and spread of modes are influenced by distances among established individuals. Asymmetric competition within local neighbourhoods can therefore generate a range of complex size distributions within even-aged cohorts.
authors.affiliation: School of Physics and Astronomy, The University of Nottingham, Nottingham NG7 2RD, UK Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Puebla, Puebla, Pue. 72001, México.
authors.forename: Jorge
authors.initials: J
authors.lastname: Velázquez
authors.affiliation: Landcare Research, P.O. Box 69, Lincoln 8152, New Zealand.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Allen
authors.affiliation: Forest Ecology and Conservation Group, Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Coomes
authors.affiliation: School of Life Sciences, The University of Nottingham, University Park, Nottingham NG7 2RD, UK markus.eichhorn@nottingham.ac.uk.
authors.forename: Markus P
authors.initials: MP
authors.lastname: Eichhorn
mesh_terms: D003198:Computer Simulation; D065928:Forests; D008954:Models, Biological; D009520:New Zealand; D013997:Time Factors; D014197:Trees / Q000145:classification / Q000502:physiology*
keywords: Fuscospora cliffortioides; bimodality; forests; individual-based model; southern beech; zone-of-influence
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