Resource dynamics and plant growth: a self‐assembling model for individuals, populations and communities

Abstract

1. We describe a new model of plant growth that is general, deterministic, non‐stationary and mechanistic in nature. Its purpose is to investigate the extent to which the morphology and function of the whole plant can be determined by resource acquisition and utilization on the part of its components. 2. The model is a two‐dimensional section, showing the plant in its above‐ and below‐ground environments. The whole plant is represented by a branching structure made up from standard ‘modules’. The behaviour of the complete plant is determined exclusively by a rule set that acts only at the level of the individual module. 3. At the level of the whole plant, the model displays a classic S‐shaped growth curve, plasticity in root–shoot allocation, and foraging in heterogeneous environments. 4. At the level of the plant population, the model exhibits self‐thinning along a –2/1 self‐thinning line. This accords with the behaviour expected of a two‐dimensional system and also adds weight to the ‘geometric’ interpretation of the –3/2 self‐thinning line commonly seen in crowded populations of real plants. 5. An imposed ‘mutation’ in one of the modular rules allows us to produce a modified plant type that displays active foraging. In a set of simulations involving a model community containing both the modified and standard plant types, the modified type predominates in resource‐rich environments, and vice versa. 6. The simulations demonstrate the effectiveness of modular rule‐based methods from which whole‐plant behaviour can arise as an emergent property. The model suggests that active foraging carries a cost that cannot satisfactorily be borne at low levels of resource availability. It also implies that competition for resources, both above and below ground is in the form of a ‘contest’ (rather than a ‘scramble’). The success of the modular model highlights the primacy of resource acquisition and utilization in determining the ecological status of the plant.

Phenotypic Plasticity and Interactions Among Plants

“…The proportional allocation of biomass to roots vs. shoots is fundamental to interactions among plants (Fitter 1994, Robinson 1994, Reynolds and D'Antonio 1996, Colasanti and Hunt 1997, Aerts and Chapin 1999. Among species, plants allocate proportionally more biomass to roots in nutrient-poor and water-poor environments and more biomass to shoots in light-limited environments (Chapin 1980, Ericsson 1995, Aerts 1999.…”

Changes in spatial point patterns of pioneer woody plants across a large tropical landslide

“…Moreover, when resources are heterogeneously distributed in space, survival of individuals with better access to them will be disproportionately favoured in relation to the neighbouring plants (i.e. asymmetric contest competition; Colasanti and Hunt, 1997). This process will generate spatial patterns of attraction between dead and surviving individuals (Jacquemyn et al, 2010;Raventos et al, 2010).…”

A conceptual framework for the study of modular responses to local environmental heterogeneity within the plant crown and a review of related concepts

“…There are several lines of evidence that support the concept of autonomous modular response. Simulation models that assume independent resource acquisition and use by modular units closely replicate real plant growth and the dynamics of population and community (Sorrensen-Cothern 1993;Takenaka 1994;Colasanti and Hunt 1997;Colasanti et al 2001;Hunt and Colasanti 2007). Experimental studies have demonstrated that between-branch or between-shoot carbon movement within plants is very limited; i.e., they demonstrated the carbon autonomy of modular units (Watson and Casper 1984;Yamamoto et al 1999;Hasegawa et al 2003;Lacointe et al 2004;Hoch 2005;Volpe et al 2008).…”