FORESTRY IDEAS, 2021, vol. 27, No 1 (61): 29–45 INFLUENCE OF CLIMATIC FACTORS ON THE FORMATION OF SCOTS PINE (PINUS SYLVESTRIS L.) AND NORWAY SPRUCE (PICEA ABIES KARST.) RADIAL GROWTH ELEMENTS IN THE BOREAL ZONE OF RUSSIA Dmitry A. Danilov1* and Dmitry A. Zaytsev2 1Institute of Forests and Natural Resources, Saint-Petersburg State Forest Technical University, 5 Institutsky lane, Saint-Petersburg, 194021, Russian Federation. Leningrad Research Agriculture Institute Branch of Russian Potato Research Centre, 1 Institutskaya Str., Gatchinsky District, Leningrad Oblast, 188338, Russian Federation. E-mails: [email protected]*; [email protected] Received: 25 December 2020 Accepted: 28 February 2021 Abstract We studied the influence of average temperatures and precipitation of the growing season on the formation of macrostructural elements of radial growth in Scots pine and Norway spruce stands of Leningrad region located in the boreal zone of the European part of Russia. Denro- climatic studies were carried out using the results of wood samples analysis from forest stands on two-layer soils collected during 60 years. The digitized parameters of wood samples were processed in a GIS system, which made it possible to obtain an array of generalized dendrochro- nologies. A rank correlation analysis of the data obtained was carried out using the Spearman’s test. To simulate the combined effect of the amount of precipitation and average temperatures on the formation of the structural elements of radial growth, the method of the quadratic function was used. Depending on the composition of a stand, there was a different response to the se- lected meteorological factors during the study period. In pine stands, the effect of the average temperature of the growing season on the amount of annual radial growth was greater than in spruce stands. In spruce and pine stands with the participation of deciduous species, the struc- tural elements of wood were more meteosensitive. The use of the quadratic function method made it possible to assess the combined effect of the total precipitation and average temperature of the growing season on the elements of radial growth of pine and spruce in the stands under study over the period of the experiment. Stands with various proportions of pine predominantly responded in the same way to changes in external factors associated with the climatic features of the region, which indicates the priority of their use in dendrochronological studies. Key words: amount of precipitation, annual ring width, average temperature, early and late wood, statistical analysis. Introduction formation about changes in the action of environmental factors (Byusgen 1906, A great number of researchers noted the Mikola 1962, Vikhrov and Protasevich ability of annual growth rings to retain in- 1965, Dergachev and Chistyakov 1993, 30 D. Danilov and D. Zaytsev Makinen et al. 2002, Grippa and Potakhin vital state of a stand, etc. For this reason, 2016). The obtained information, on one the revealed correlations between the cur- hand, is chronological, that is, it repre- rent radial growth and meteorological fac- sents the variability of annual growth in tors are, in fact, statistical, reflecting their time, the presence of temporary cyclical influence on the intensity of the use of wa- changes, and the direction of changes ter-mineral soil resources in accordance (Mielikäinen et al. 1996). On the other with the vital state of the stand. hand, this information is associated with It has been noted that the growth rate exogenous and endogenous environmen- of annual rings of Scots pine and Norway tal factors (Eckstein et al. 1989). spruce of the same age growing in the Radial growth of stem wood of for- Baltic region in different habitat conditions est-forming woody plants is a complex in- was not the same against the background tegral indicator, to the formation of which of changes in weather factors (Bitvinskas the genotype of each particular plant and 1974, 1984). a complex of environmental factors con- Variability in radial growth of conifer- tribute. Radial growth of trees is a bioin- ous trees in Central and Eastern Europe dicator, and the characteristics of tree and in Northern Fennoscandia was main- growth rings can show changes in the en- ly associated with changes in the sum of vironment (Babushkina et al. 2010). positive temperatures of the growing sea- A large number of publications have son (Mikola 1962; Makinen et al. 2000, been devoted to the variability of tree 2001, 2002, 2003). In contrast, in Central growth, but many issues remain debat- Europe variation in growth of conifers was able or poorly understood, due to the di- mainly correlated with precipitation (Eck- versity of both forest biogeocoenoses and stein et al. 1989, Kahle 1994, Kahle and the nature of environmental impacts, as Spiecker 1996). Studies of precipitation well as the differences in research meth- effect on annual radial growth of Norway ods (Henttonen 1990, Demakov 2005, Va- spruce carried out in southern and central ganov et al. 2006, Zaytsev et al. 2020). Finland have also revealed that damage Climatic factors have a particularly and dying off of spruce in drought-sen- strong effect on the growth rate. By de- sitive areas in the southern part of the viating from the long-term average they country could be primarily related to low produce response in plants (Mitryajkina precipitation rather than temperature fluc- 2005). tuations (Mikola 1962; Henttonen 1990; Since a complex of factors affects Mielikäinen et al. 1996; Miina 2000; Maki- growth and development of plants during nen et al. 2000, 2001, 2002, 2003). their life cycle, the relationship between Makinen et al. (2002, 2003) stud- the width of annual growth rings and cli- ied changes in radial growth of Norway matic parameters is not always unambig- spruce (Picea abies (L.) Karst.) and its uous. dependence on various climatic vari- Meteorological values such as air tem- ables. The researchers compared for- perature and precipitation directly influ- est stands in southwestern and eastern ence the development of dendrocoenoses Germany, Norway and Finland. Climate (Miina 2000). However, the growth of the models included local temperature and trunk mass of trees also depends on soil precipitation, and temperature anomalies. nutrients, moisture, depth of groundwater, Trees growing in moderate conditions Influence of Climatic Factors on the Formation of Scots Pine (Pinus sylvestris L.) ... 31 have been found to be less responsive Material and Methods to climate change. Changes in spruce growth were clearly correlated with tem- To correctly identify the consequences of perature. the influence of meteorological parame- When the Baltic countries were consid- ters on tree growth, only forest stands on ered, on moist soil growth of Scots pine similar soils and in similar hydrological was more sensitive to precipitation of the conditions should be considered. The se- previous year (Daukane and Elferts 2011). lection of sampling points is a key issue Studies of interannual differences in dendroclimatic research. It determines in growth of Scots pine tree rings at the sensitivity of trees under study to various northern border of the range under the environmental factors. conditions of the European North have To study the influence of meteorologi- revealed consistency in long-term growth cal factors on annual growth of Scots pine and the same response to changes in and Norway spruce, studies were carried environmental conditions (Tyukavina and out in pure and mixed coniferous stands of Lezhneva 2014, Tyukavina 2015). In dif- the same age class (85–100 years) of the ferent growing conditions, pine reacted to bilberry (Vaccinium myrtillus L.) series of unfavourable factors more synchronously forest types in the conditions of Oredezh than to optimal ones. plateau of Luga-Oredezhsky landscape According to a number of authors, in region of Leningrad region located in the the taiga geocomplexes of the Europe- Northwest of the European part of Russia. an North of Russia, the amount of radial Geographic coordinates of study area are growth of wood is limited by the ratio of 59°16’58” N and 30°14’24’’ E. heat and moisture, both in the atmos- The natural stands under study have phere and in the soil, especially during not been affected by human activities and the growing season (Grippa and Potakhin grow on soils with two-layer structure. The 2016, Chudakov et al. 2020). landscape types under consideration are The analysis of wood samples collect- widespread in the boreal zone of Valdai ed from large territories by scientists from glaciation area: within the moraine plain different countries made it possible to and along the tops and slopes of north-fac- consider tree growth as an indicator of the ing moraine hills. Two-layer sediments are dynamics of biological systems in space rocks of a loamy or sandy composition of and time in connection with changes in low thickness (30–70 cm) occurring on natural conditions and anthropogenic in- loams, which serve as the first imperme- fluences at the local, regional and global able horizon from the surface. The main scales (Martínez-Sancho et al. 2020). distinguishing feature of the hydrolog- In connection with the above, it is nec- ical regime of drained soils on two-layer essary for forestry practice to determine sediments is the presence of a surface stands with less dependence on variations soil-groundwater horizon in April-May and of limiting meteorological factors. The aim September-November which screens the of the study was to analyse the influence loam located below (Chertov 1981). of meteorological parameters on the for- The climate of the area is Atlantic-con- mation of annual growth and its structur- tinental, with relatively mild winters with al elements in Norway spruce and Scots thaws and moderately warm summers. pine stands of various compositions. The prevailing winds are westerly and 32 D.