Abstract
Currently there are studies which suggest that the number of orchid species on islands is except their size and latitude also positively corelated with thier connectivity on other islands. This may be due to the fact that higher locality connectivity means also higher colonization probability of a new species thanks to higher probability of species seed dispersal.
This dependence could apply also in a smaller scale within a single continent or country, but this has not been tested so far. Probability of occurrence of a single orchid species on locality can be also affected by the history of locality.
On sites unaffected by human (by ploughing or fertilization) it is possible to expect a higher probability of occurrence of a single orchid species than on anthropogenic sites. The effect of anthropogenic influence can decline in time because the locality can return to natural state and can be recolonized from surrounding living populations again.
The effect of these opposing opinions on the orchid occurence is not known. The aim of this study is, with the aid of existing historical and recent databases of terrestrial orchid species occurrence on a selected area, to test the following hypothesis: 1) The probability of occurrence of a single terrestrial orchid species depend on connectivity of selected locality. 2) The probability of occurrence of a single terrestrial orchid species depend on history of selected locality.
First we will start in South Bohemia area with the first five most abundant species. Maybe we will be able to extend the study area and species to whole Czech Republic, alternatively to foreign countries.