Ecology of Plantago Populations
The performance of plants in the field differs due to the environmental conditions and genetic variation between plants. Demographic studies provide basic material for investigations of the ecophysiological aspects of the adaptation to the environment and of the selection processes which have given rise to adaptation. The demographic work in the project includes a comparison on different levels: between species, between populations of a single species and, in some cases, comparison between spatial subdivisions within a single population. The last mentioned studies have been carried out to determine the scale on which genetic differentiation occurs and will be treated in Chapter 7. They are essential to define accurately a population. Theoretically a population can be defined as a group of individuals which (potentially) interbreed, and which is more or less separated from other groups (Bakker 1964). The results of the detailed studies showed that inhomogeneity in the habitat or variation in the management of the vegetation can cause genetic variation between the local plant groups. When demographic plots are chosen in a relatively homogeneous vegetation, with greatest distances in the order of metres, no genetically determined variation between the plots can be expected. Thus plots with a distance of in most cases less than 10 m (in the two Achterberg sites maximally 25 m) in a visually homogeneous vegetation as used in our demographic studies were regarded as representing a single population.
KeywordsBiomass Clay Phosphorus Convection Depression
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