Zur ökophysiologischen und ökogeographischen Differenzierung nah verwandter Carlina-Arten

Abstract

The aim of this study was to investigate the ecophysiological differentiation between two closely related plant species with different distribution. The areas of Carlina vulgaris a South-Central-European, and C. biebersteinii an East-European-Middle-Siberian element overlap in Central Europe, where both species could be studied in the field and in a transplant garden. Dry matter partitioning and vertical leaf area distribution are similar in both species. However, leaf structure, stomatal behaviour, rooting pattern and organ temperatures differ significantly. In C. biebersteinii leaves are more mesomorph, stomata are more sensitive to dry air and root length per unit leaf area is much smaller than in C. vulgaris . Under radiation conditions leaf and flower temperatures in C. biebersteinii are higher than in C. vulgaris . Changes in leaf sequence are more pronounced in C. biebersteinii . Thus, C. biebersteinii shows features that appear adequate for moderate light and high humidity conditions in dense herbaceous plant canopies, whereas C. vulgaris is a typical heliophytic forb of open habitats. This corresponds with the different natural growth conditions of the two species: C. biebersteinii grows in relatively dense canopies under conditions of a short but prevailingly humid growing season (East-European-Siberian forest step) whereas C. vulgaris is found in open pioneer habitats with periods of water-stress during a much longer growing season (Submediterranean-Central-European areas). Finally we discuss the ecological significance of the large leaf area accumulation on the flowering heads of both species with respect to gas exchange.