The central aim of this thesis is to investigate the morphological root responses of floodplain plant species to flooding and to soil nutrient heterogeneity, the relation between these responses and their consequences for plant growth and performance. Both flooding and soil heterogeneity play a role in floodplain habitats and plants growing here have to deal with both factors to a certain extent, depending on the elevation level. The morphological root responses of plant species to flooding on the one hand and nutrient heterogeneity in the soil on the other hand are investigated. We asked whether a trade-off in the responses to these factors exists in eight plant species, originating from different habitats in the floodplain. An extension of this study with three wetland species is also described, as well as an experiment in which soil flooding and nutrient heterogeneity are combined. Plants were successively subjected to both factors, in order to determine whether and how the root responses to flooding and nutrient heterogeneity are expressed in the same individual. Rumex palustris proved to be very plastic in its root responses. In natural soils, spatial and temporal variability in nutrient availability is high and patches are likely to appear and disappear frequently, and this seems particularly true in the habitat of R. palustris. We studied whether there are costs associated with the disappearance or switch in location of nutrient-rich patches in the soil for R. palustris, after the roots proliferated in the patch. We also present the results of a competition experiment with R. palustris and Agrostis stolonifera. In its natural habitat, R. palustris does not experience much competition, but its high selective root placement suggests a high competitive ability for nutrients belowground. We thus investigated whether the high selective root placement of R. palustris is beneficial when it has to compete for nutrients in the soil.

Radboud University Nijjmegen, Experimental Plantecology, 13 maart 2007

Contains fulltext : 30066.pdf (Publisher’s version ) (Open Access)

Promotor : Kroon, J.C.J.M. de

117 p.