Pall. shrubs occurring only on the northern slopes at 2100-2900 m a.s.l. (Dolukhanov, 2010). These birch-dominated forests are widespread in the subalpine belt of the Kazbegi district of Georgia (Nakhustrishvili et al., 2006).Currently, birch forests have significantly decreased in the temperate zone worldwide. They are represented as treelines only in four regions (Dolukhanov, 2010): Mount Etna (Sicily) -Betula aetnensis Raf., the Caucasus -B. litwinowii, the Himalayan range -B. utilis D. Don and B. ermanii Cham., and mount Fujiyama (Japan) -B. ermanii. The deciduous subalpine birch forests of the Central Greater Caucasus Mountains in the Kazbegi district of Georgia are represented by a combined species composition where B. litwinowii is a dominant treeline species. The main plant species associations in a birch forest habitat are represented by Betula raddeana Trautv.,

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The Colchis forests contribute to the biodiversity hotspot in the Caucasus eco-region. We investigated the plant diversity of these forests in the central part of Adjara (W Georgia). The aims of our study were (i) to differentiate the forest vegetation diversity in the mountain belt forests by means of phytosociology, (ii) to associate endemic taxa with the revealed forest types, and (iii) to assess degradation of the forest vegetation diversity by means of environmental abiotic and biotic factors. We sampled the forest vegetation on 135 plots with the size of 10 × 10 m2 and 237 plant taxa were recorded. Principal Component Analysis (PCA) was used to reduce environmental variables to a few orthogonal composed variables. The derived factors (PC1, PC2) were used in ordination analysis to group the plot measured forest vegetation diversity. One-way ANOVA was used for the comparison of means between the separated clusters in PCA. Two-Way Indicator Species Analysis (TWINSPAN) and Indicator Species Analysis (ISA) were applied for the association of the plant taxa with the vegetation cluster groups separated by PCA. Our analysis revealed two general ecologically distinct forest types which were characterized as dry and humid forests. Endemic species had the main occurrence in dry forests of the studied territory which are heavily impacted by the local land use. The results indicated that the vegetation diversity of dry forests is under higher threat of degradation than that of humid ones because these forests are not protected and are subjected to non-sustainable forest exploitation. Additionally, many rural and invasive plant species change the native plant assemblages. Based on our findings, we recommend to the organization which manages the local forests to find a balance between the use of forest resources and protection of the unique floristic diversity of local forests in order to avoid their degradation.

Preliminary study carried out in Georgia in the framework of limestone quarries in V. Kavtiskhevi, Municipality of Kaspi, Shida Kartli in coordinates 41°88' N-44°44' E, elevation 386-709m. Post-closed rehabilitation process of the limestone quarry area after finishing the cement production is extremely interesting to use this territory for scientific investigations of industrial impact on nature and the methods of habitat rehabilitation. Plant species composition and diversity was determined for each habitat. Plant species are 114 total numbers in described on the territory (182.98h) of the quarry. The endemics are 10 species: Shrubs (3); herbs (6), geophytes (1). The vegetation cover percentage is much lower in pioneer successions (29.4±14.4) than in oligotrophic grasslands (67.8±16.1). The species richness shows similarly low level at pioneer succession (9.7±1.6) than in oligotrophic grasslands (16.4±3.9). Shannon-Wiener index is higher in restored grasslands (1.9±0.48) than in pioneer successions (1.6±0.53). DCA show that the pioneer succession is mainly clustered with environmental indicator of low soil depth. The mean soil depth pioneer succession plots is lower (1.7±1.76cm) than in oligotrophic grasslands (2.75±1.13cm). The plant species presented in the second group of the dominant species are demonstrating the higher frequency: Poterium polygamum (70.8%), Poa pratensis and Trisetum rigidum (66.7%), Plantago lanceolata (62.5 %). the first dominant species Dorycnium pentaphyllum sub sp. herbaceum occurs only in 58.3% of the plots. The second dominant species Bothriochloa ischaemum occurs only in 37.5% of the plots. The frequency of other three species of the first dominant group-Lotus corniculatus, Glycyrrhiza glabra and Inula aspera equals to 20.8%. Plant species are standard deviation, and minimum and maximum values were calculated for each quantitative data set one-way ANOVA. The area of Kavtiskhevi is semi-arid zone and the vegetation is adapted to dry matter of clay soil.

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