Zur Entwicklung ausgewählter Populationen des Kletten-Labkrautes (Galium aparine L.)

Abstract

Summary The environmental plasticity and strategy within the life cycle of Galium aparine populations in different ecosystems were examined basing on selected morphological and productivity parameters. Within the course of investigations the existence of two different tactical pathways of the annual ontogenetic cycle has been confirmed. 1. After a successful start the developmental conditions during the late phase of vegetative extension and the reproductive phase are deteriorating rapidly. So the populations are forced to shorten these developmental phases resulting in a very weak reproductive output (seeds). This tactics is followed by populations of forest- and ruderal-ecosystems with strong competitors and by individuals of all the other phytocoenoses emerging at the end of emerging time (spring). 2. Initially unfavourable developmental conditions (frost period) are followed by a period enabling the population to use her specific growth-form for producing a high biomass. This fact secures an enlarged reproductive phase with a high reproductive effort. This tactics is typical for Galium aparine populations of low competitive ruderal-coenoses and agro-ecosystems emerging in autumn and those populations emerging in spring in agro-ecosystems cultivated by spring crops. Apart from those both environmentally conditioned tactics deviations of the basic strategical programme have been observed, representing genetically fixed ecotypes. The evolution of an ecotype fitted to run a complete summer-annual short cycle after emerging in late spring has to be interpreted as an adaptation enabling Galium aparine to tolerate successfully the special life conditions of such anthropogenic ecosystems.