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Michel Droz

Publications and source records attributed to Michel Droz.

2 recordsLinked to original sources
bioRxiv2016

ROLE OF TOLERANCE TO RESOURCE DEMAND -- SUPPLY MISMATCH IN A MODEL OF ANNUAL PLANTS

We propose and discuss a simulation model of annual plants competing for a single resource. Plants are characterised by their tolerance to a shortage of it and the maximum number of seeds a plant could produce in a year. Interaction among plants is reduced to blocking a part of the resource by the plants nearest neighbours. Spatial and temporal external conditions remain unchanged. We consider two systems - plants of one type (target plants) and a mixture of two types, when the second type differs from the target ones only by the tolerance to a shortage or surplus of the resource. We show how the life cycle of a plant depends on its tolerance, supply of the resource and how it is affected by the presence of the second type of annuals. We demonstrate that coexistence of the two species is possible, and we determine the conditions for it.

Ecology↗
bioRxiv2016

COMPARISON OF TWO DESCRIPTIONS OF HETEROGENEITY USED IN MODELLING PLANTS DYNAMICS

We analyse the role played by two different approaches of spatial heterogeneity in theoretical models of annual plants dynamics. The first approach is called quasi-continuous gradient in which one type of resource is changing gradually along the gradient line. In the second one, called the patches approach, part of the habitat is covered by patches and the resource has a different value in each patch. We show that when the spatial heterogeneity of the habitat is small, the two approaches yield the same average number of surviving species, even if a small number of patches is used. In a strong heterogeneity it takes many patches to get similar results as in the gradient case. The difference between the gradient and patchy description of the spatial heterogeneity increases with the number of species present in the system. We have also shown that even when the average number of surviving species is the same, the abundances of species are ordered in a different way, like different species are the dominant ones. The conclusion of this paper is that modelling spatial heterogeneity in a system of plants is not a simple task. Special care is needed when the heterogeneity of the habitat is large, since then depending of the choice of a method, some predictions may differ significantly, making the model non-robust. Therefore the type of theoretical approach must closely match the modelled ecosystem.

Ecology↗