Population biology of several couples of congeneric species in relation to the fragmentation of their respective habitats

Project leader: Tania Walisch (Department of Population biology - Databases, Museum of Natural History, Luxembourg (e-mail).
Collaborators: Diethart Matthies (Department of Biology, Plant Ecology, University of Marburg) (e-mail), Guy Colling (Department of Population biology - Databases, Museum of Natural History, Luxembourg (e-mail)

Traditional hay meadows (¹⁾ have declined drastically during the past decades mainly due to changes in agricultural practices. The resulting fragmentation is bound to have an effect on the populations of typical plant species present in these meadows.

The aim of the project is to identify the existing and potential effects of rapid habitat fragmentation on hay meadow vegetation. Populations of typical meadow species (Lychnis flos-cuculi L., Potentilla erecta (L.) RÄUSCHEL and Saxifraga granulata L.) will be compared to populations of congeneric species occurring on rock faces in Luxembourg (Lychnis viscaria L., Potentilla rupestris L., Saxifraga rosacea MOENCH subsp. sternbergii (WILLD.) KERGUELEN et LAMBINON). Rock faces are naturally isolated and exhibit a fragmentation level which is more or less stable in time. Populations of the rock species L. viscaria, P. rupestris, S. rosacea subsp. sternbergii have maintained themselves at the same sites in Luxembourg during at least 50 years and we suppose they are adapted to their fragmented habitat⁽²⁾.

During field and laboratory studies we will investigate the relation between the level of fragmentation of a number of populations of the congeneric species and demographical characteristics as well as reproductive biology characteristics (pollination, fruit set, seed set). Furthermore the genetic and morphological variation of progeny within the populations and between the populations will be studied.

The obtained results may eventually enable us to evaluate a viable level of habitat fragmentation for the studied meadow species.

⁽¹⁾ Hay meadows are listed under mesophile grasslands in annex I of the European ‘Habitat’ Directive (92/43/CEE).

⁽²⁾ The level of fragmentation of a population depends on one hand on the gegraphical distance to the next population and on the other hand on the size of the population.