The results of Dracaena sub-populations research are submitted in this dissertation. Dragons Blood Tree is an endemic plant species growing on the Socotra Island. The thesis contains four scientific papers published or submitted for review in journals with impact factor and in peer-reviewed journal. The first article predicts sub-population dynamics on Firmihin where the ha sample plot inventory was carried out. Tree growth and mortality simulation has been created using a time horizon of 100 years. The second article is focused on growth dynamics of seedlings growing ex situ under controlled conditions. One hundred plants from Firmihin and Skand have been measured once a week for two years. The differences in growth dynamics and mortality for both groups of young plants in ex situ were evaluated. The third article also relates to Dragons Blood Tree regeneration and deals with a possibility of in-situ regeneration in the fenced area on Shibehon Plateau compared to Oam al-Cora school grounds. The team from Mendel University in Brno planted hundreds of seedlings in 2006, ever since the monitoring of growth dynamics and mortality continues. The fourth article deals with anatomy of secondary thickening plant organs. Xylem, phloem, parenchyma and vessels area of root, stem and branch was determined using 70 permanent microscope slides and processed by image analysis. The results were evaluated, compared and graphically interpreted.

Dracaena cinnabari, the dominant endemic tree of Socotra Island (Yemen), is in serious decline. The effect this will have on the island's plant diversity remains unknown. This dissertation aimed to assess the possible role of Dracaena as a nurse plant by identifying plants associated with Dracaena understorey and by assessing the importance of Dracaena for maintaining plant diversity. In the first part of the dissertation, relevés sampled in Dracaena understorey and in open sites to record the number of individuals of vascular plants were analysed. Species richness and composition were compared between understorey and open sites, and species associated with each of these habitats were identified. Additionally, the effects of shading and leaf litter on species richness and abundance were analysed. The second part of dissertation focused on mature woody species composition of Dracaena stands and investigated spatial relations between Dracaenas and other mature woody plants. The last part of the dissertation aimed to assess the fine scale spatial relationships between stones and plants in Dracaena stands and evaluated the differences of these relationships between understorey and open sites. The results confirmed the Dracaena role as an important nurse plant. The tree enhances the environmental heterogeneity and its presence creates two distinct microhabitats (understorey and open sites). The understorey habitat, compared with open site, harbours higher number of species, including endemics. The species in Dracaena stands can be classified as either understorey specialists, open-site specialists or generalists. The decline of Dracaena will negatively affect plant diversity, will reduce abundance of rare endemic plants and will lead to homogenization of vegetation. As no other tree species exists which could replace the Dracaena, our findings underline the importance of conservation efforts to preserve Dracaena stands on Socotra and identify this species as a key umbrella species whose conservation would ensure also the protection of a number of other associated species.

Diploma thesis is focused on establishment of forest nurseries and seedling production on Socotra Island where a natural regeneration of many endemic species is limited by overgrazing and has been moreover affected by cyclone that hit the island in 2015. Planting stock of Dracaena cinnabari, Boswellia elongata, Boswellia ameero, Boswellia dioscorides, Punica protopunica, Aloe perryi and mangrove Avicennia marina was planned to be propagated in nurseries located in three areas of interest – Firmihin, Homhil and Niyt. Therefore data about the species seed germination or growth rate were gathered and mentioned in the literature section. The species selection was always firstly preceded by dendrological survey of the area. Individual pilot areas were also described together with climatic data and moreover, soil samples were analysed as the substrate for the seedling production comes from local sources. Finally, the projects for forest nurseries establishment were created and according to them were individual nurseries established.