Modelling individual growth and competition in plant populations: growth curves of Chenopodium album at two densities
Authored by J Weiner, C Damgaard, H Nagashima
Date Published: 2002
DOI: 10.1046/j.1365-2745.2002.00700.x
Sponsors:
Danish Environmental Research Programme
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
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Abstract
1 We modelled the growth in estimated biomass of individuals in
experimental populations of Chenopodium album grown at two densities and
measured sequentially nine times over 128 days. Competition is modelled
by coupling individual growth equations and, within the population, the
growth rate of a plant at any point in time is a function of its size to
the power a , a measure of the degree of size-asymmetry of competition.
2 The growth of individuals in these crowded populations was
significantly better fit by a Richards growth model than by models with
one fewer parameter (e.g. logistic or Gompertz growth models). The
additional parameter determines the location of the inflection point and
provides great flexibility in fitting growth curves. Density had a
significant effect on this parameter.
3 At the higher density, the maximum size that plants achieved was
decreased and the exponential phase of growth was reduced. The estimate
of the size-asymmetry parameter a was always greater than 1 and it
increased significantly at the higher density. Growth was reduced and
the number of very small individuals increased at the higher density, although a few plants still achieved a large size.
4 Our approach combines several recent innovations in the modelling of
stand development, including (a) modelling of individual growth with
biologically meaningful growth models and (b) modelling the relationship
between size and growth of individuals within the population.
Sequential, non-destructive data on the growth of individuals over time, in combination with modern statistical computing techniques, can lead to
major advances in the modelling of plant population development, providing powerful tools for exploring variation in individual growth
and for testing a wide range of hypotheses.
Tags
Dynamics
dominance
Mechanisms
Size distribution
Dependence
Asymmetric competition
Monocultures
Suppression
Frequency-distributions