Abstract
The effect of three forms of active species protection in the Roman snail were studied. On the “source plot” the natural population was supported by introducing hatchlings of farmed Roman snails aged 1+, bred from adult specimens of this population. These hatchlings (age 1+) from “source plot” population were also introduced to the following two natural plots: to the “empty plot”, where the population was formed by introduction of farmed Roman snails in the second year of life (1+) into a selected area which had been emptied of the natural population; to the “inhabited plot”, where farmed Roman snails aged 1+, originating from breeding snails of the foreign population from a “source plot”, were introduced to the local natural population. It was established that introducing Roman snails aged 1+ and bred under farm conditions has a clearly positive influence on the age structure of the natural population in the studied plots. The rate of growth of these snails adjusted to the rate of growth of the specimens in the same age group belonging to the natural population. The farmed Roman snails grew most rapidly in the “empty plot” sown with fodder vegetation, more slowly in the “source plot” with access to appropriate herbaceous vegetation, and most slowly in the “inhabited plot”. The attempt to create a naturalized population in a specially adapted “empty plot” without the natural population was successful. This was determined not only by a large number of hiding places from calcareous stones available to the Roman snails but above all by the species structure of the herb flora, which met their nutritional requirements as it contained high proportions of plants such as Brassica rapa × Brassica rapa subsp. chinensis, white clover (Trifolium repens), red clover (Trifolium pratense) and the hybrid of lucerne (Medicago × varia Martyn)