Objects of the exploration are the natural populations of Gentiana lutea L. and Gentiana punctata L., which are scanty on the territory of Bulgaria and difficult to be restored. The two species areincluded in the Red Data Book of Bulgaria and are protected by the Nature Protection Law.

A complete characteristic of the distributions of the two species is made - location, altitude, exposure, slope, and type of the rock base and soil. A general projective covering if the phytocoenosis with the participation of the two species has been reported. In order to characterize the condition of the populations the surface, which the two species occupy, as well as the projective covering of each of the two species have been given an account. The age structure of some populations of Gentiana lutea and Gentiana punctata has been determined.

Gentiana lutea L. and Gentiana punctata are perennial plants plants with valuable medicinal qualities and high decorative value. Their distribution areas spred over the mountines of Central and South Europe (the area of Gentiana lutea reaches Asia Minor) both species are Central European geoelements.

In Bulgaria Gentiana lutea grows in grassy places and on rocky slopes in the mountains from 1200m to 2600m altitude. Gentiana punctata is seen in dry grassy and rocky areas and especially on scraps between 1500m and 2880m altitude. (Kožuharov and Petrova 1982; Bondev 1995).

The goal of present exploration is to establish the distribution of the two species on the territory of Bulgaria, to make an ecological characteristics of their places of habitats as well as an estimation of the condition of their populations.

The exploration on the populations of Gentiana lutea and Gentiana punctata are carried out in the period 1997-1999. 16 populations of Gentiana lutea and 22 populations of Gentiana punctata have been investigated on the territory of five floristic regions. For each of the populations the altitude, slope, exposure, basic rock and soil have been determined.

The condition and renovation possibleties of the populations are followed by establishing their surface, space and age structures and reproductive possibilities. The Quantitative participation of each of the two species has been determined through their projective covering. The projective covering is expressed by the correlation of the general surface of the population to the surface of their area parts. Total projective covering of the phytocoenosis in which Gentiana lutea and Gentiana punctata participate, also has been studied.

The populations of Gentiana lutea L. are found oh the territory of five floristic regions in Bulgaria - Rila, Stara planina, Vitosha, Pirin and the Rodopa Mountains (table 1). The investigated habitats are located between 1600 m and 2300 m altitude. This corresponds to the data from the literature for the vertical distribution of the species (Bondev 1960).

The habitats of the species represent rocky sub-alpine slopes or forest clearings near the upper forest boundary. The exposure is most often south or with south component (sometimes at a lower altitude the species could be located on slopes with other exposure). The inclination varies between 10 and 40 degrees. The rock base is most often silicate, but it is also to be seen on limestone (the populations in the region of Koziata stena in Stara planina and Pogledetz in Pirin. -No 10, 15 in table 1). The humidity is most often atmospheric. The soil type is modic cambisols.

The greater part of the population which Gentiana lutea forms are scanty, consisting of single samples. Very strongly spread with Gentiana lutea is the vegetative reproduction because the species possesses very huge rizoma, which forms enormous clones. Due to this reason even by populations occupying bigger territories it often represents a clone population of few individuals. Exceptions are populations No 2, 9, 15, 16 which occupy very big territories. Except vegetatively the species reproduce by seeds where the seeds develop themselves at the presence of enough humidity and preserve their germination up to two years (Borisova 1957). The seed formation is good and 80 % of the formed seed cases are with normally developed seeds. The number of seeds in one seedcase is between 70 and 100, the number of the blossoms in one node is 45-50 and there are 4-5 nodes on one stem.

A characteristic peculiarity of the biology of Gentiana lutea is the fact that the species blossoms through several years, whereas the suckers, which form the blossom, stem rest on the next year and the rosettes which have been sterile the previous season blossom.

The explored populations of Gentiana punctata L. are on the territories of four floristic regions - Rila, Stara planina, Vitosha and Pirin Mountain (table 2). In the literature (Urumov 1935 there are data about this species for its distribution in Osogovo but during the investigations carried out by us Gentiana punctata has not been confirmed for the mentioned area.

The habitats are located between 1800m and 2500m altitude, i.e. the species is reaching higher in comparison with Gentiana lutea. Itslocations are divers - alpine meadows and slopes (often with a great inclination of 45 degrees), among rocky streams and scraps as well as in communities of dwarf pine. Some of the populations occupy sections in which snowdrifts are retained till late in the spring (the population in the region of Lake Malka Maliovitza - No 3 in table 2) - these types of locations are quite well damped. The habitats of the species are with different exposure - most often north. The northern slopes are with higher and comparatively more constant air humidity in comparison with the slopes situated at the same altitude but turned to the south. Gentiana punctata has been established only on a silicate base. Comparatively less in number are the populations of Gentiana punctata in Stara Planina (No 17, 18, 19) as well as the populations in Vitosha and Pirin Mountain (No 20, 21, 22). Some of the populations of Gentiana punctata in Rila Mountain are with exclusively big dimensions and with high density (No 8, 11, 14).

Gentiana punctata forms clones with multiple vegetative and generative rosettes. This species preserves the density of its population mainly through vegetative reproduction by rhizoma suckers because with a part of the generative samples the production of seeds is impeded. The lower seed reproductive potential (compared to the one of Gentiana lutea) is probably due to the lower number of blossoms - 7 blossoms per one stem as an average.

Age structure of the populations of Gentiana lutea and Gentiana punctata:

The age structure is determined through reporting the individuals of different age groups per unite surface (1 sq. m.) and the plants are divided in three age groups (graphs 1, 2, 3):

a - juvenile - the rosettes formed by them by basic leaves are with small dimensions;
b - middle aged (vegetative) - their rosettes are with the dimensions of mature plants;
c - mature (generative).

Graph 3.


CONCLUSION

16 Populations of Gentiana lutea from five floristic and 22 of from 4 floristic have been investigated in the present exploration. The populations of Gentiana punctata as a whole are more numerous and with higher density and they are more multiple in comparison with the populations of Gentiana lutea. The greatest numbers of explored populations are on the territory of Rila - 16 populations of Gentiana punctata and 7 populations of Gentiana lutea and among them the populations of Gentiana punctata are more numerous and with higher density in comparison with the populations of Gentiana lutea. On the territory of the remaining floristic areas the two species are represented by a small number of populations. The main reason for their limited distribution is the anthropogenic influence, which brings to destroying of entire population. Having in mind that the reproduction by seeds is quite uncommon this brings to a real threat of extinction. The present research work confirm the nature preservation status of the two species - protected by the Nature Protection Law and included in the Red Data Book of Bulgaria - in the category threatened with extinction.

1. Bondev I. (1960): Vertical distribution of few plants in Rila Mountain. Izv. Bot. Inst. 7, 27-32.

2. Bondev I., ed. (1995): Chorological atlas of medicinal plants in Bulgaria. BAN. 90-92.

3. Borisova N. A. (1957): Vedenii gorechavki zeltoi Gentiana lutea v proizogstvenuiu kulturi. Bot. Zurnal. 42 (3), 462-472.

4. Ivashin D. S. (1960): Semennoe i vegetativnoe vozobnovlenie Arnica montana i Gentiana lutea v Ukrainskih Karpatah. Bot Zurnal. 45 (7), 1039-1044.

5. Kožuharov St. and Petrova A. (1982): Genus Gentiana - in: Flora of PR Bulgaria. Vol. 8, BAN, 397-398.

6. Urumov Iv. (1935): Florata na Kjustendilsky okrag. Sb. BAN. 30, 1-235.