Status and development trends of Scots pine plantations outside the species areal in Bulgaria
DOI:
https://doi.org/10.2478/foecol-2026-0012Keywords:
climate change, competition, ecosystem fit, heat-moisture balance, mortality, Pinus sylvestris LAbstract
Our study attempted to find a spatial analogue of the anticipated climate change in present times by investigating the status and development trends of four half-century-old man-made Scots pine stands outside the species areal in Central and North-Eastern Bulgarian lowlands. Stand composition, competition intensity, stand stability, site quality, tree mortality and ecosystem fit according to nationally established standards, were evaluated and growth correlations with climatic variables were analysed. Two stands experiencing an ongoing dieback were distinguished, regardless of the good productivity potential of the trees (Stand 2) or the low competition pressure and good mechanical stability maintained (Stand 1). The other 2 plantations showed either no mortality (Stand 4) or mortality due to self-thinning (Stand 3), forming a relatively productive and dense pure Scots pine stand (Stand 4) or a mixed, highly productive stand with diverse composition and good structure and stability (Stand 3). Tree growth was positively affected by the summer and the annual precipitation amounts, while negative correlation was found with the summer heat moisture index. Our investigation revealed that pine growth still can be sustained even in a slightly humid climate, if a high productivity level and good stand structure are assured, that indicates the overall capability of the species to adapt. However, the Scots pine trees are not able to adapt to relatively dry environmental conditions, suitable for lowland thermophilic species such as oaks, where the stands collapse when the heat-moisture balance worsens.
References
Aleksandrov, N., Tonchev, T., 2021. Ecosystem fit of Scots pine (Pinus sylvestris L.) plantations in south-western Bulgaria. Baltic Forestry, 27 (2): 601. https://doi.org/10.46490/BF601
Allen, C.D., Breshears, D.D., McDowell, N.G., 2015. On underestimation of global vulnerability to tree mortality and forest die-off from hotter drought in the Anthropocene. Ecosphere, 6 (8):129. http://dx.doi.org/10.1890/ES15-00203.1
Allen, C.D., Macalady, A.K., Chenchouni, H., Bachelet, D., McDowell, N., Vennetier, M., Kitzberger, T., Rigling, A., Breshears, D.D., Hogg, E.H. (Ted), Gonzalez, P, Fensham, R., Zhang, Z., Castro, J., Demidova, N., Lim, J.-H., Allard, G., Running, S.W., Semerci, A., Cobb, N., 2010. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. Forest Ecology and Management, 259: 660–684. https://doi.org/10.1016/j.foreco.2009.09.001
Bravo-Oviedo, A., Sterba, H., del Río, M., Bravo, F., 2006. Competition-induced mortality for Mediterranean Pinus pinaster Ait. and P. sylvestris L. Forest Ecology and Management, 222 (1-3): 88–98.
Dimitrov, P., 2025. Tree species distribution modelling using stand-level forest inventory data – a Pinus sylvestris L. case study in Bulgaria. Silva Balcanica, 26 (2): 61–83. https://doi.org/10.3897/silvabalcanica.26.e159961
Elfving, B., Kiviste, A., 1997. Construction of site index equations for Pinus sylvestris L. using permanent plot data in Sweden. Forest Ecology and Management, 98 (2): 125–134.
Executive Forest Agency, 2011. Klasifikatsionna shema na tipovete gorski mestorastenia v Narodna Republika Bulgaria [Classification scheme of the forest site types in the People's Republic of Bulgaria]. Sofia: BULPROFOR Publishing Centre. 90 p. (In Bulgarian).
Fontes, L., Bontemps, J.-D., Bugmann, H., Van Oijen, M., Gracia, C., Kramer, K., Lindner, M., Rötzer, T., Skovsgaard, J.P., 2010. Models for supporting forest management in a changing environment. Forest Systems, 19 (SI): 8–29.
Gendreau-Berthiaume, B., Macdonald, S.E., Stadt, J.J., 2016. Extended density-dependent mortality in mature conifer forests: causes and implications for ecosystem management. Ecological Applications, 26 (5): 1486–1502. https://doi.org/10.1890/15-0887
Georgieva, M., Petkova, K., Molle, E., 2024. Effects of needle cast diseases on the growth of a 33-year-old Douglas-fir provenance plantation in northwestern Bulgaria. Folia Oecologica, 51 (2): 175–184. https://doi.org/10.2478/foecol-2024-0017
Gordon, J., Bormann, B., Jacobs, L., 1996. The concept of ecosystem fit and its potential role in forest management: a primary research challenge. In Korpilanti, E., Mikkela, H., Salonen, T. (eds). Caring for the forests: research in changing world. IUFRO 20th World congress, Tampere, Finland, 6–12 August 1995. Congress Report. Vol. 2. Vienna, Austria: Finnish IUFRO World Congress Organising Committee, p. 21–28.
Grosenbaugh, L.R., 1965. Generalization and reparameterization of some sigmoid and other nonlinear functions. Biometrics, 21 (3): 708–714.
Hamilton, D.A., 1986. A logistic model of mortality in thinned and unthinned mixed conifer stands of Northern Idaho. Forest Science, 32 (4): 989–1000.
IPCC, 2007. Working Group I Report 104. The Physical Science Basis. New York, USA: Cambridge University Press.
IPCC, Caud, N., Chen, Y., Goldfarb, L., Gomis, M.I., Huang, M., Leitzell, K., Lonnoy, E., Matthews, J.B.R., May-cock, T.K., Waterfield, T., Yelekçi, O., Yu, R., Zhou, B., 2021. Summary for Policymakers. In Masson-Delmotte, V., Zhai, P., Pirani, A., Connors, S. L., Péan, C., Berger, S. (eds). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel On Climate Change. Cambridge, United Kingdom and New York: Cambridge University Press, p. 3–32. https://doi.org/10.1017/9781009157896.001
Husch, B., Beers, T., Kershaw, J., 2003. Forest mensuration.4th ed. Hoboken: John Wiley and Sons, Inc. 443 p.
Kostov, G., 2014. Ideya za klasifikatsia na kulturite ot byal i cheren bor spored nivoto na ekosistemno saotvetstvie [An idea for classification of the Scots pine and Black pine plantations according to the level of ecosystem fit]. Forest, Sofia, 9: 19–21. (In Bulgarian).
Kostov, G., Aleksandrov, N., Tonchev, T., 2023. Adaptivno stopanisvane na byalborovite kulturi [Adaptive management of Scots pine plantations]. Sofia: Intel Entrans. (In Bulgarian).
Krastanov, K., Belyakov, P., Shikov, K., 1983a. Opredelyane na boniteta na byalborovite kulturi [Determination of the site index of Scots pine plantations]. In Nedyalkov, S., Rashkov, R., Tashkov, R. (eds). Reference book in dendrobiometry. Sofia: Zemizdat, p. 333. (In Bulgarian).
Krastanov, K., Belyakov, P., Shikov, K., 1983b. Obemni i sortimentni tablitsi za byalborovi kulturi [Volume and assortment tables for Scots pine plantations]. In Nedyalkov, S., Rashkov, R., Tashkov, R. (eds). Reference book in dendrobiometry. Sofia: Zemizdat, p. 57–69. (In Bulgarian).
Koulelis, P.P., Solomou, A., Fassouli, V., Petrakis, P.V., Spanos, I., 2025. Radial growth and climatic influences on Greek fir: Tree ring analysis from Kirphi mountain, Central Greece. Folia Oecologica, 52 (2): 113–123. https://doi.org/10.2478/foecol-2025-0012
Larsson, L., 2022. CooRecorder and Cdendro Programs of the Coorecorder, Vers. 9.8.1. [cit. 2025-07-31]. https://www.cybis.se/forfun/dendro/
Marchi, M., Castellanos-Acuna, D., Hamann, A., Wang, T., Ray, D., Menzel, A., 2020. ClimateEU, scale-free climate normals, historical time series, and future projections for Europe. Scientific Data, 7: 428. https://doi.org/10.1038/s41597-020-00763-0
Monserud, R. A., 1976. Simulation of forest tree mortality. Forest Science, 22: 438–444.
Nykänen, M.L., Peltola, H., Quine, C.P., Kellomäki, S. Broadgate, M., 1997. Factors affecting snow damage of trees with particular reference to European conditions. Silva Fennica, 31 (2): 193–213.
Panayotov, M., Vasilev, V., Tsvetkova, N., Kovachev, A., 2023. Glava 3. Ekologichni nishi na osnovni darvesni vi-dove v Yugozapadna Bulgaria i modeliraneto im za ochakvani badeshti klimatichni uslovia [Chapter 3. Ecological niches of major tree species in Southwestern Bulgaria and their modeling for expected future climate conditions]. In Panayotov, M., Tsvetanov, N. (eds). Klimatichni promeni i vliyanieto im varhu gorite v Yugozapadna Bulgaria. Sofia: Intel Entrans, p. 13–135. (In Bulgarian).
Penev, N., Garelkov, D., Marinov, M., Naumov, Z., 1969. Tipove gora v Bulgaria [Types of forests in Bulgaria]. Sofia: Publishing House of the Bulgarian Academy of Sciences, 354 p. (In Bulgarian).
Peltola, H., Kellomäki, S., Välsänen, H., Ikonen. V.P., 1999. A mechanistic model for assessing the risk of wind and snow damage to single trees and stands of Scots pine, Norway spruce and birch. Canadian Journal of Forest Research, 29: 647–661.
Petty, J. A., Worrell, R., 1981. Stability of coniferous tree stems in relation to damage by snow. Forestry, 54 (2): 115–128.
Pinheiro, J.C., Bates, D.M., 2000. Mixed-effects models in S and S-PLUS. New York, USA: Springer Verlag. 537 p.
Pogrebnyak, P.S., 1955. Osnovy lesnoi tipologii [Fundamentals of forest typology]. Kiev: Publishing House of the Ukrainian Academy of Sciences. (In Bulgarian),
Popov, G., Kostov, G., Markoff, I., Dodev, Y., Georgieva, D., 2018. Iglolistnite kulturi v Bulgaria sazdadeni izvan estestvenia im areal [The coniferous plantations in Bulgaria, established outside their natural range]. Sofia, Bulgaria: Avangard Prima. 124 p.
Pretzsch, H., 2009. Forest dynamics, growth and yield. From measurement to model. Berlin Heidelberg, Germany: Springer-Verlag. 671 p.
Pretzsch, H., Del Río, M., Arcangeli, C., Bielak, K., Dudzinska, M., Forrester, D.I., Klädtke, J., Kohnle, U., Ledermann, T., Matthews, R., Nagel, J., Nagel, R., Ningre, F., Nord Larsen, T., Biber, P., 2023. Forest growth in Europe shows diverging large regional trends. Scientific Reports, 13 (1): 15373. https://doi.org/10.1038/s41598-023-41077-6
Raev, I., Alexandrov, V., Tinchev, G., 2015. Assessment of drought related climate change impacts on forests in Bulgaria. Silva Balcanica, 16 (1): 15–24.
Raev, I., Knight, C.G., Staneva, M. (eds), 2003. Zasushavaneto v Bulgaria. Savremenen analog na klimatichni promeni [Drought in Bulgaria. A contemporary analog for climate change]. Sofia, Bulgaria: Publishing House “Prof. Marin Drinov” of the Bulgarian Academy of Sciences. 284 p. (In Bulgarian).
Raev, I., Rossnev, B., 2003. Chapter 6. 1. Vazdeystvie na zasushavaneto varhu izkustvenite ekosistemi [Influence of the dry period on the man-made forest ecosystems]. In Raev, I., Knight, C. G., Staneva, M. (eds). Zasushavaneto v Bulgaria. Savremenen analog na klimatichni promeni Sofia: Publishing House “Prof. Marin Drinov” of the Bulgarian Academy of Sciences, p. 121–153. (In Bulgarian).
Riahi, K., Van Vuuren, D.P., Kriegler, E., Edmonds, J., O’Neille, B.C., Fujimori, Sh., Bauer, N., Calvin, K., Dellink, R., Fricko, O., Lutz, W., Popp, A., Cuaresma, J.C., Samir, K. C., Leimbach, M., Jiang, L., Kram, T., Rao, Sh., Emmerling, J., Ebi, K., Hasegawa, T., Havlik, P., Humpenöder, F., Da Silva, L.A., Smith, S., Stehfest, E., Bosettii, V., Eomd, J., Gernaat, D., Masui, T., Rogelj, J., Strefler, J., Drouet, L., Krey, V., Luderer, G., Harmsen, M., Takahashi, K., Baum-stark, L., Doelman, J.C., Kainuma, M., Klimont, Z., Marangoni, G., Lotze-Campen, H., Obersteiner, M., Tabeau, A., Tavoni, M., 2017. The shared socioeconomic pathways and their energy, land use, and green-house gas emissions implications: an overview. Global Environmental Change, 42: 153–168. https://doi.org/10.1016/j.gloenvcha.2016.05.009
Schröder, J., Gadow, K.V., 1999. Testing a new competition index for Maritime pine in northwestern Spain. Canadian Journal of Forest Research, 29 (2): 280–283.
Sileshi, G.W., 2014. A critical review of forest biomass estimation models, common mistakes and corrective measures. Forest Ecology and Management, 329: 237–254. http://dx.doi.org/10.1016/j.foreco.2014.06.026
Skovsgaard, J.A., Vanclay, J.K., 2008. Forest site productivity: a review of the evolution of dendrometric concepts for even-aged stands. Forestry, 81 (1): 13–31. https://doi.org/10.1093/forestry/cpm041
Stankova, T.V., González-Rodríguez, M.Á., Diéguez-Aranda, U., Ferezliev, A., Dimitrova, P., Kolev, K., Stefanova, P., 2024. Productivity-environment models for Scots pine plantations in Bulgaria: an interaction of anthropogenic origin peculiarities and climate change. Ecological Modelling, 490: 110654. https://doi.org/10.1016/j.ecolmodel.2024.110654
Thurm, E.A., Hernandez, L., Baltensweiler, A., Ayan, S., Rasztovits, E., Bielak, K., Zlatanov, T.M., Hladnik, D., Balic, B., Freudenschuss, A., Büchsenmeister, R., Falk, W., 2018. Alternative tree species under climate warming in managed European forests. Forest Ecology and Management, 430: 485–497. https://doi.org/10.1016/j.foreco.2018.08.028
Tkach, V., Bondar, O., Rumiantsev, M., 2020. Pedunculate oak stands in the catchments of the river Vorskla’s tributaries. Folia Oecologica, 47 (1): 70–80. https://doi.org/10.2478/foecol-2020-0009
Tkach, V., Rumiantsev, M., Kobets, O., Obolonyk, I., 2024. The outcomes of Quercus robur natural regeneration after clear-cutting in the north-eastern part of Ukraine. Folia Oecologica, 51 (2): 136–145. https://doi.org/10.2478/foecol-2024-0013
Tsvetanov, N., Aleksandrov, N., Panayotov, M., 2024. Response of Norway spruce (Picea abies (L.) Karst) to warming climate: a case study from Bulgaria, Southeastern Europe. Ecologia Balkanica, 16 (2): 30–45. https://doi.org/10.69085/eb20242030
Vizcaíno-Palomar, N., González-Muñoz, N., González-Martínez, S.C., Alía, R., Benito Garzón, M., 2019. Most southern Scots pine populations are locally adapted to drought for tree height growth. Forests, 10 (7): 555. https://doi.org/10.3390/f10070555
Visual Crossing Corporation, 2025. Global Weather Data and API for Every Application. [cit. 2025-09-02]. www.visualcrossing.com
Wagenmakers, E.J., Farrell, S., 2004. AIC model selection using Akaike weights. Psychonomic Bulletin & Review, 11 (1): 192–196.
Weiskittel, A.R., Hann, D.W., Kershaw Jr, J.A., Vanclay, J.K., 2011. Forest growth and yield modeling. Chichester, UK: John Wiley and Sons, Ltd. 418 p. https://doi.org/10.1002/9781119998518
WRB, 2014. IUSS Working Group WRB. World reference base for soil resources 2014, update 2015. International soil classification system for naming soils and creating legends for soil maps. World Soil Resources Reports, no. 106. Rome, Italy: FAO, 203 p.
Zhu, J., Li, X., Liu, Z., Cao, W., Gonda, Y., Matsuzaki., T., 2006. Factors affecting the snow and wind induced damage of montane secondary forest in northeastern China. Silva Fennica, 40 (1): 37–51.
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