Abstract
The main objective of our investigations was to examine how the intensity of vegetative growth and reproduction is connected with the success of insect catching and the conditions of inhabitation of different carnivorous plants species.
In order to achieve our goal, we had made diary observations in July of 1999 and in July and August of 2000. Carnivorous plants Drosera rotundifolia, D. x obovata, D. anglica and Pinguicula vulgaris in the Louchskiy region of the Karelia Republic on the shore of the White Sea were studied. All of the 127 studied plants were marked with individual markers, and once each day the number of caught insects and the number of leaves on every studied plant were counted. Also the length and the width of the largest leaf, the length of its petiole, the diameter of leaf rosette, and the distance between the plant and the border of the population, which this plant belongs to, were measured for each plant. All the received data was processed with the computer-based program STATISTICA for Windows (StatSoft, Inc., 1995).
The measurements of 893 Drosera rotundifolia plants were made, along with the continuous observations on two plants of Drosera rotundifolia and two plants of Pinguicula vulgaris.
The intensity of vegetative growth and reproduction of all the studied species of carnivorous plants and the success of their insect catchings depend, for the most part, on the weather conditions. Thus, from our investigations and literature data, we will conclude that carnivorous plants hardly endure the drought, due to their superficial root system. The intensity of vegetative growth also depends in part on the content of nutritious substances in the soil. The success of insect catchings by carnivorous plants can change in constant habitation conditions depending on the total number of insects.
The intensity of vegetative growth and reproduction of all the studied Drosera species is connected to the number of insects caught by the plant. This states that the more insects the plant manages to catch, the greater it is in size. In converse to the previous statement, the number of insects caught depends on the size of the plant. There was not such a connection for Pinguicula vulgaris.
The differences in morphology and orientation of varying leaves of different Drosera species influence the number and specie structure of the caught insects. According to our data, Drosera anglica is larger in size and is more successful at catching a greater amount of insects than are Drosera rotundifolia and D. x obovata. In conclusion, Drosera anglica is more capable of adaptations for obtaining insects than the two other studied species of Drosera.
The recovering of carnivorous plants areas is natural conditions. The observed differences in the way of influence of captured insects on the plants functions and means of insects catching can be explained by the aspiration of the plants to reduce the intergeneric competition.
The length of the petiole of Drosera rotundifolia expands with the increase in the distance between the plant and the border of the population, to which the plant belongs. During a similar predicament, the number of insects caught by D. anglica and D. obovata decreases, while the length of petiole remains constant. The given data allows us to address the inpopulation competition in all of the studied species of plants.
The analysis of the data allows us make the following conclusions:
1. The intensity of flowering of all the studied carnivorous plant species depend on their size.
2. The success of insect catchings by all of the studied carnivorous plant species depend on weather conditions and total number of insects available.
3. The number of leaves of carnivorous plants depend on the weather conditions and the content of nutritious substances in the soil.
4. All of the studied Drosera species have inpopulation competition.
5. The connection between the size of all the studied Drosera species and the number of insects caught by the plant were disclosed
6. The number of caught insects does not influence the characteristics of Pinguicula vulgaris.
7. Drosera anglica is more capable of adaptations for the catching of insects than the two other studied Drosera species.