about us


Site general description
The site “Petrohan” occupies the territory of the Training and Experimental Forestry Enterprise (TEFE) "Petrohan" is situated on the northeast slopes of the West Balkan range (Berkovsi Balkan) with a total area of 7192 ha. The relief of the region is typical mountain, steep, with deeply cut river valleys and secondary watersheds with lowest point at altitude 350 m, and highest at ¬1900 m. At the territory of TEFE "Petrohan" a ecological station is build situated between 23°04' N and 23°13' E at 1470m height.

Ecosystem characterization
The site “Petrohan” falls into the North-Bulgarian climatic zone with moderate continental climate. In the low mountain parts it is characterized by vegetation period of 5,5 months, mean annual temperature 8,¬9° С and mean annual precipitation between 600-750 mm. In the middle mountain part the vegetation period is 4¬5 days, temperature is 5,5¬7° С, and precipitation 850 to 1000 mm. The hydrological network in the studied region is dense (rivers Burzia, Kadiiska, Gavaneshtiza etc.) with constant water flow during the whole year. The prevailing soil type in the region is brown forest soil (Distric-Eutric-Cambisols), on granite, with mean depth up to 80 cm, pH of the soil solution is 4.5 to 6.0 рН, C/N - 12-14 and the contents of nitrogen in the soil over 1%. The main tree species Fagus silvatica L. cosists 81,7 % all area. The rest tree species are distributed as follows: Pinus silvestris L. - 5,8 %, Picea abies (L.) Karst - 4,0 %, Carpinus betulus L.- 3,7 %, and other broadleaves - 2,0 %. The part of protective forest are high - 74,4 %, which is differentiated as area for water resources. This beech forest ia one of the best measured and managed forest in Bulgaria. Its management began in 1893. The average parameters are as follows: total stock - 1 989 695 m3; stock per ha - 298 m3; total annual growth - 24271 m3; growth per ha - 3,64 m3. The investigated beech forests are one of the best forest in EU.They are unique with their productivity and multifunctional use.

Available data and parameters
Ecosystem investigations, such as hydrochemical, hydrological, soil, phytopathological, and investigations on bio-productivity and resumption have been carried out in ecological station “Petrohan” since 1986. Hydrochemical investigations in this area include determination of bulk depositions, throughfall deposition of beech and spruce trees, steam flow as well as the flow of pollutants by soil solution and stream waters (Ignatova, 1989, 1994, 2007; Ignatova, 1991, 2001; Ignatova и Fikova, 2005; Dambrine et al., 1998; Ignatova & Dambrine, 2000; Ignatova et al., 2004; Ignatova & Myashkov, 2004; Fikova & Ignatova, 2002, Fikova, 2003). The following parameters are observed: water quantity, рН, concentrations of NO3-, SO42, Cl-, NH4+, K+, Na+, Ca2+, Mg2+ ions, as well as some the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests operating under the UNECE Convention on Long-range Transboundary Air Pollution (UN-ECE, 2005). Since 1996 the critical loads and their exedence for nitrogen, sulfur and acidity for forest soil and surface waters in the region have been determined and mapped, as a part of EMEP Bulgarian network (Ignatova et al., 1999; 2003, 2004; 2007), according methodology of the International Co-operative Programme on Modelling ang Mapping of Critical Loads and Levels (UBA, 1996, 2004). Critical loads for heavy metals for forest ecosystems and surface waters have been defined since 2001. (Ignatova et al., 2002, 2005, 2006, 2007).

Expected additional parameters and indicators
The site is perspective for studying relationships between key ecosystem parameters and global climatic changes.

Responsible Institution – University of Forestry, Sofia

Site coordinator & reference person

Prof. Dr Nadka Ignatova
University of Forestry,
10 Kl. Ohridsky Blv.,
1756 Sofia
Phone: +359 2 91907/ 351
Fax: +359 2 8622830
E-mail: Nadia_ignatova@abv.bg

The University of Forestry (Sofia) manages a field station with facilities and buildings.

Research projects and funding institutions
The study site is financed by the University of Forestry
200 ICP Modelling and maping of critical loads since 2000
ICP water
2006-2008 Evaluation and maping of critical loads of S, N, pH and heavy metals in forest ecosystems in Bulgaria 998/22.12.-MOEW)
200 2007-2009: Evaluation and maping of critical loads of acid pollution in Bulgaria – MOEW
And 8 projects more funding by MOEW, 2 – funding by MES

Main references
Dambrine, E., B. Pollier, M. Bonneau, N. Ignatova, 1998. Use of artificial trees to assess dry deposition in spruce stands. Atmospheric Environment, vol. 32, N 10, pp. 1817-1824.
Fikova, R. Ignatova, N. 2002. Output/input ratios of pH, nitrates and sulfates in soil solution under different vegetation types in a region with acid precipitation: a dynamics assessment by time series analysis. Ecology (Bratislava). Vol.21, 3, p. 283-297.
Ignatova N., 2007. Hydrochemical monitoring in forested catchments in Bulgaria for assessment of the risk of stream water acidification. Proceedings of the 23 meeting of ICP Waters, Nancy, October, 2007, p. 11-17.
Ignatova, I., Dambrine, E., Fikova, R., 2004. Acidification of stream waters in forested catchments. Forest idea, 2 (30), 74-83 (in Bulgarian, English abstract).
Ignatova, N., 1989. Comparative studies on the correlation between tree vegetation and precipitation water in the West Balkan Range. In: Verification of hypotheses on the mechanisms of damage and possibilities of recovery of forest ecosystems. E. Klimo and J. Materna (Eds.) Brno, p. 119-130.
Ignatova, N., 1994. Augmentation recente du depot des polluants atmospheriques par les precipitations dans deux regions forestieres de Bulgarie. The Science of the Total Environment, 151, p. 167-179.
Ignatova, N., 2006. Developments in calculation and mapping critical loads of acidifying pollutants and heavy metals for terrestrial and aquatic ecosystems in Bulgaria. Proc. Of VII th Subregional meeting of ICP “Modeling and Mapping critical loads in Europe”, Baia Mare, p. 26-38.
Ignatova, N., Damianova, S., Fikova, R., 2007. Sustainable management of surface waters by determination of heavy metals critical loads. Management and Sustainable development, 18: 3-4, 187-196 (in Bulgarian, English abstract).
Ignatova, N., E. Dambrine, 2000. Canopy uptake of Nitrogen deposition in spruce (Picea abies L. Karst) stands. Annals of Forest Science, 57, p. 113-120.
Ignatova, N., I. Myashkov, 2004. Using CORINE Land Cover classification to assess and map the sensitivity of forest ecosystems in Bulgaria. Proc. of workshop on CORINE Land Cover (B. Mohaupt-Jahr, M. Keil and R. Kiefl Eds.), 20-21 January, Berlin, 2004.
Ignatova, N., K. Jorova, I. Myashkov, M. Grozeva, R. Fikova, 2004. Critical loads and Dynamic Modelling results. Bulgaria. CCE Progress Report (J.P.Hettelingh, J. Slootweg, M. Posch Eds.), 53-58.
Ignatova, N., K. Jorova, I. Myashkov, R. Fikova, 2003. Modelling and mapping of critical thresholds in Europe. Bulgaria. UN/ECE Status report 2003 of Coordination center for effects N 259101013 (M. Posch, J.-P. Hettelingh, J. Slootweg, and R. J. Downing Eds.). RIVM, Bilthoven, Netherlands, p. 53-58.
Ignatova, N., K. Jorova, M. Grozeva, R. Fikova, 2002. Preliminarymodelling and mapping of critical loads for cadmium and lead in Europe. Bulgaria. UN/ECE report of Coordination center for effects N 259101011 / 2002 (J.-P. Hettelingh, J. Slootweg, M. Posch Eds.). RIVM, Bilthoven, Netherlands, p. 69-75.
Ignatova, N., K. Jorova, Е. Velizarova, R. Fikova, M. Broshtilova, 2005. Modelling and mapping of critical loads for cadmium and lead in Europe. Bulgaria. CCE Progress Report (J.P.Hettelingh, J. Slootweg, M. Posch Eds.), RIVM, Bilthoven, Netherlands, p. 69-75.
Ignatova, N., R. Fikova, K. Jorova, M. Grozeva, 1999. Comparative calculations of critical loads, using depositions in coniferous and deciduous forests. Proceedings of Training workshop on critical loads calculations for air pollutants, 27 September-2 October 1999, Pushcino, Russia, pp. 100-110.
Ignatova, N., S. Damyanova, K. Jorova, Е. Velizarova, R. Fikova, M. Broshtilova, Y. Yordanov, 2007. Critical loads of Nitrogen and Dynamic modeling. Bulgaria. CCE Progress Report (J. Slootweg, M. Posch, J.P.Hettelingh Eds.), RIVM, Bilthoven, Netherlands, p. 115-120