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Zhodnocení výskytu a růstu jmelí bílého (Viscum album) na vybrané lokalitě
Halfar, Jan
European mistletoe (Viscum album L.) is an evergreen semi-parasitic plant, with a wide host range of both deciduous and coniferous trees. As a native species, this plant is widespread throughout Europe. The first part of this paper is aimed as a literature review, which includes a description of European mistletoe, a general description of its occurrence and its effect on host woody plants. The second part focuses on a survey of a selected area between the villages of Bělá and Chuchelná (Opava district), where the degree of infestation of individual trees, the species of infested trees and their age are assessed. At the same time, the number of mistletoe plants, their distribution in the crown, and in the oldest mistletoe specimens their age and haustorium length were determined at three sites in the forest area belonging to the Lesy města Brno a.s. In this work it was found that mistletoe occurred mainly on Scots pine at site 1, but was also found on silver fir and small-leaved linden. At site 1, mistletoe began to invade pine after the age of 30. Mistletoe in young stands grew mainly on trees with the greatest high growth and in the upper part of the crown. On the basis of these results, I recommend to concentrate the management of mistletoe-infested forest stands on tree age above 30 years during planned thinning and to actively remove infested individuals from the stand. Changing the species composition of forest stands in favour of mistletoe-resistant species is also one of the ways to prevent the spread of mistletoe in threatened areas. At site 2, the age of the largest mistletoe shrubs ranged from 9 to 18 years. The longest measured haustorium was 18 cm in length and was measured on mistletoe at 17 years of age. From the measurement results, a relationship between mistletoe age and haustorium length was found. Knowing the haustorium length is important in the context of tree protection when performing branch pruning. Therefore, based on the results of this work, I recommend removing infested branches at a minimum distance of 30 cm from the mistletoe shrub, especially for older mistletoes.
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Strukturně funkční charakteristika průduchů jmelí bílého (Viscum album L.) a jeho hostitele lípy (Tilia sp.)
Bělíček, Dominik
This thesis deals with a comparison of the morphology of the stomata of the hemiparasite European mistletoe (Viscum album L.) and its host lime tree (Tilia sp.) in the context of physiological parameters such as water potential, stomatal conductance, and photosynthesis, in order to understand the relationship between the two species. The research was carried out at the Ústřední hřbitov in Brno. Here, 10 infested and 10 uninfested lime trees were selected. During the summer of 2022, varnish impressions were taken from the leaves of lime and mistletoe trees and then all physiological parameters were measured. It was found that mistletoe infestation had almost no significant effect on both the morphology and physiology of lime tree leaves. Furthermore, it was shown that mistletoe has more smaller stomata than linden. It has been shown that although mistletoe has a higher stomatal conductance, the photosynthetic rate is the same for both species, thus the water use efficiency of mistletoe is much lower. It was confirmed that mistletoe, as a hemiparasite, has a much lower water potential than the host. Although this information helps to understand this interrelationship, it also results in further uncertainties worth to investigate in future.
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