| Abstract [eng] |
The genus Thesium in Lithuania is represented by 2 species: Thesium ebracteatum Hayne and T. linophyllon L.. Both these species are included into the Red Data Book of Lithuania (T. ebracteatum under protection is since 2003 and T. linophyllon – is protected since 2007). Both Thesium species are ascribed to the group of vulnerable species. Furthermore, T. ebracteatum is included in to the Annex II of the EU Habitat Directive. Investigations on cenopopulations of T. ebracteatum were performed in 2003 and 2006 during June–July. Five cenopopulations were investigated. The aim of this study was to investigate populations of T. ebracteatum and to reveal dependence of population state upon habitat conditions. The study revealed that abundant and viable cenopopulations of T. ebracteatum usually occur in open, well-illuminated sites. Individuals of this species, as a rule, are well developed, with higher number of flowers. When meadows and slopes overgrow with shrubs and trees, because of law illumination T. ebracteatum flowers poorly, does not reproduce by seeds and occurs as vegetative shoots only. Accumulation of dead herb and leaf litter as well as dense and thick moss cover influence coenopopuliations of T. ebracteatum especially negatively. Results of this investigation revealed strong positive correlation between abundance of Medicago falcata and Knautia arvensis in the habitat. These species are, probably, important host plants for Thesium ebracteatum. In order to sustain or improve viable cenopopulations of T. ebracteatum, urgent conservation measures should be taken. The most important task is to protect and sustain favourable conservation conditions. The aim can be achieved by creation and thorough implementation of management plan for this species. |
