| Popis: |
Gymnosperms have various structure of needles. These needles are often exposed to different light conditions in various parts of the crown. Therefore, coniferous trees began to adapt to a different intensity of solar radiation by changing the morphology and anatomy of needles. These adaptations concern the tree both in the stands and urban environment. This bachelor's thesis is focused on comparing characteristics of sunny and shady needles of Scots pine. The aim consists in determining the effect of light on the anatomical and morphological structure of needles, which are located in different world sides and within different levels of the crown. Needles undertook measurement of parameters as follows: needle width and thickness, needle area, central cylinder area, xylem and phloem area. World sides were found having no effect on anatomical and morphological structure of needles. In contrast, needles at the base of the crown (shaded) had a smaller area comparing with those needles from the top of the crown (sun). The solar radiation amount is one of the main factors determining the anatomical and morphological structure of needles. A sudden change in lighting conditions (thinning, seedlings remove, building removal) may therefore lead to the crown stress and necrosis. For this reason, while planting in urban environment, it is necessary to consider the light demands of trees as well as light conditions, in which the plants had been grown. |
