Issues

Plenary lecture representing the history of establsihment and development of the subject "Ecology and environmental protection" in the University of Forestry - Sofia, Bulgaria.

Secondary succession for the period 1995-2007 has been observed in permanent plots. The following measures were established and analyzed: rate of succession, species composition change and abundance. We found that the species' compositional change is slowing down in time. This process is more obvious in the shrub and perennial groups. Mean abundance through different life forms remains unchanged, excluding perennial herbs, which abundance is significantly lower. As a result of the changing environment, we should expect an increase in shrub and tree abundance and decrease in annual and biennial herbs. Continuous changes in composition and abundance show that the windfall areas are in the establishment phase, which is the first stage of the secondary forest succession. 

The conditions of the chestnut forests were worsening in a global scale during the last decades. It was manifested in prematurely defoliation, drying-up, development of semiparasites, diseases and pests. It was consider that in Bulgaria the main causes for this were old age, wrong sylviculture management and some diseases - mainly Phytophtora cimiamoni Pand., Ph. cambivora Bnis. and Cryphonectria parasitica Murr. The great number of investigations had been started for the clarifying of the main factors which provoke it. A set of international, regional and national conferences were carried out.

The present research was part of the investigations of the structure of these communities in Bulgaria. The floristic composition of the chestnut communities (Castaneta sativae) along West Balkan mountains was investigated in the present paper. A total of 139 species of vascular plants were described. The structure of the studied flora based on biological type, life form (17) and floristic elements (4) was determined.

The comparative floristic analysis between the chestnut forests in Belasitsa and Slavianka mountain has been made.

GIS was used for mapping and spatial analysis of chestnut formation areas. GIS applications allow performing SQL queries and criteria look-ups and assembling of thematic maps.

This dendrary is situated within the peripheral sub-region in the Mountain of Strandzha, on the territory of the State Forestry of Tsarevo. Nitrogen and macroelements conets have been examined in the leaves of 16-20-year old tree species as Pinus nigra Arn. ssp. Austriaca Hoss, Pinus nigra Arn. ssp. Iaricio Poiret, Cedrus deodara Loud., Cedrus atlantica Man. Cedrus libani Laws., Cypressus semepervirens L., 3 origins of Quercus petraea Liebl., 4 origins of Quercus robur L., Quercus pubescens Willd., Quercus rubra L., Quercus suber L., Quercus harwissiana Stev., Quercus frainetto Ten., Fagus silvatica L., Fagus orientalis Lipsky and Tilia argentea Desf, within the period as from 2004 up to 2007.

N content in the leaves of the most of the deciduous species is the greatest in June, maintaining comparatively high values in July and gradually lowering in the further months, when the vegetation period occurs. In October, N concentration in the leaves of some of the species drops to a half of its previous value. P2O5 content is at its maximum value in the summer months, keeping its relatively high values by the end of the vegetation period. K2O concentration in the leaves of the most of the species is the highest in August. Ca and Mg contents is characterized by an increase from the beginning to to end of the vegetation period.

N, P2O5 and K2O contents in the coniferous species is about 2 times lower as compared to that one, found out in the leaves of the deciduous species, and it is that same which makes the latter ones more unpretentious to soil fertility. The lowest is the concentration in the needles of the Atlas cedar species (Cedrus atlantica Man.). The highest is the content in the leaves of the silver-leaf lime tree (Tilia argentea Desf.) and in those ones of the oak species growing in the mountain of Strandzha while the lowest one results in the leaves of the corkwood (cork oak). There are also differences observed among the single origins within a definite species.

No significant differences have been found out between the coniferous and deciduous species, as regards to Ca and Mg contents. It has been noted, Mg and Ca concentrations in the cedar needles results twice higher approximately than that one found out in the black pine needles

The flora of the Kremikovtsi Mine comprises 74 species, 62 genera and 24 families. Asteraceae (24), Poaceae (10) and Fabaceae (5) are the most numerous families. Boraginaceae, Chenopodiaceae, Salicaceae and Scrophulariaceae have 3 species each. Apiaceae, Equisetaceae, Lamiaceae and Polygonaceae have 2 species each. Euphorbiaceae, Juncaceae, Onagraceae, Papaveraceae, Pinaceae, Plantaginaceae, Ranunculaceae, Resedaceae, Rosaceae, Simarubiaceae and Vitaceae have 1 species each.

The object of this research are the oak forests in three mountains in Southwest Bulgaria - Ograjden, Maleshevska mountain and Vlahina. A new syntaxonomic scheme of the communities has been suggested on the basis of 243 phytocoenotic relev's. The paper provides a description of 8 groups in a synoptic table. On the basis of a syntaxonomic analysis 3 of them have been classified to belong to the following associations which have already been described: Querco cocciferae-Carpinetum orientalis Oberdorfer 1948 em. Horvat 1954, Digitali viridiflorae-Quercetum frainetto Gamisans et Herbard 1980, Genisto carinalis-Quercetum petraeae Bergmeier in Bergmeier et Dimopoulos 2008. Two new associations - Cisto incani-Quercetum pubescentis, Cyclamini hederifoli-Quercetum frainett? and three communities - Cephalanthera rubra-Quercus pubescens, Theucrium polium-Quercus pubescens, Vicia cracca-Quercus frainetto are established.