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The infuence of known regulatory factors on the population dynamics of selected orchid species on the orchid meadow (Peklo locality)
ČEPA, Luboš
Populations of strongly endangered species Orchis mascula and endangered Dactylorhiza majalis were monitored at Peklo area since 2000. In May 2002, another strongly endangered orchid species Orchis ustulata was discovered. The major increase in counts of O. ustulata towards stable numbers of O. mascula and D. majalis populations was detected during the seven year period of plant monitoring. The aim of this study was to reveal a connection between the climate conditions and orchid vitality, using biometrical plant data gained between 2005 to 2011. In order to evaluate a steady state of investigated area, the extensive phytocoenological sampling was conducted. The obtained data revealed several different loci at the screened grassland, which can be defined with presence of distinctive species. In blooming individuals of O. mascula, March temperature was the most defining factor. Parameters studied (number of leaves and blossoms, size of leaves, lenght of stems and duration of flowering) increased with decreasing March temperature. The blooming proved to be important factor, if a plant was in flower that year or the preceeding year, the number and the size of leaves was larger. The blooming in two subsequent years enhanced this described effect even more. The comparison of blooming individuals of O. ustulata revealed that plants growing in clusters were non flowering but bigger in size. Other positive correlation with investigated parameters had precipitation in December. However, the comparison of all plants showed generally smaller size of cluster forming plants. This overall analysis pointed out the influence of low temperature in October, the plants were smaller in size and amount of sterile individuals rised. All collected data and generated comparisons support earlier findings about influence of temperature and precipitation on the orchid population dynamics.
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