0507-B4
Yu. V. Savva, E.A. Vaganov 1
We studied 16 and 12 pine provenances from provenance trials established in 1964 and 1974 in southern taiga and forest-steppe, Central Siberia. Eight tree-ring width and density characteristics were measured densitometrically.
Cluster analysis identified the provenances into three groups within trials. The first group consists from the provenances originated geographically close to a test site; the second one consists from remote provenances; and the third one consists from northernmost provenances (forest-tundra and northern taiga). Climatic responses of the groups are somewhat different. For the provenances planted in southern taiga: the increase of April temperature favors to cell production and formation of a wide latewood for the provenances from the first group; warm summer hastens growth of the provenances from the second group; increase of July precipitation positively influences growth of the provenances originated from dry regions. For the provenances planted in forest-steppe: the increase of April temperature positively influences radial growth of all provenances; increased precipitation in July favors to increase of latewood percentage for the provenances from the second group; significant influence of May temperature is registered only by the northernmost provenance.
Significant differences between the provenances relate to latewood formation. There is a negative correlation of the latewood dimension, its density and its sensitivity to climatic factors with the latitude of seeds origin. Northern provenances retain their ability to maximally use the energetic resources of the first half of the vegetation season. Despite the differences in response of provenances to environmental factors the coefficients of correlation, sensitivity and Euclidean distances showed that that provenances differ from the local one by no more than 13-15%.
Tree-ring analysis is evidence of the retention of genetically fixed response to climatic factors proper to pines' origin. Nevertheless genetically fixed ability is not great, that proves high pine' adaptability to rapid climatic change.
Evidence for global warming over the past 200 years is overwhelming (Hulme et al. 1999), based on both direct weather observation and indirect physical and biological indicators such as retreating glaciers and snow/ice cover, increasing sea level, and longer growing seasons (IPCC 2001). A global assessment by the Intergovernmental Panel on Climate-Change (IPCC) found that future global warming could occur at a rate of 0.1 o C to 0.4 o C per decade (Watson et al. 1996). This rapid rate of change outstrips the ability of all but pioneer species to migrate to suitable new environments. This may significantly affect a seasonal growth of trees, rate of phenophase changes, etc.
Fitness of woody plants to new environment is closely related to the concept of adaptation of trees. The adaptation of trees to new environment, and hence, to abrupt climatic change can be studied experimentally by analysis of provenance trials established in a certain environment from seeds of different geographic origins (Matyas et al. 1992). The growth of the provenances can be regarded as a model of abrupt climatic changes and a shift of the boundaries of natural climatic zones.
The adaptation is the variability of individuals or population expressed in increased survival or growth rate; fitness of morphological and anatomical structure to environment (Gindel 1957, Write 1978). The study of the nature of adaptation in trees is concluded in the identification of conditions and factors which are responsible for variability of phenotypic and genotype traits and properties (Nekrasov 1973). Tree-ring characteristics (radial growth and wood density series) integrate the biological processes of wood formation such as cell division, radial extension and cell wall deposition (Larson 1994). On the one hand genetic program controls xylem differentiation, but on the other hand environmental factors influence these processes (Barnett 1981, Savidge 1996). Thus the analysis of tree-ring characteristics can be considered as a tool for evaluation of the genetic control of xylem differentiation, and finally of tree ring, under current environment. Moreover, the study of interannual variability in tree-ring width and density characteristics allows to identify the factors responsible for tree-ring formation of different provenances and evaluate the adaptive capacity of species to a new environment. In the present study, the results of two provenance tests were used to evaluate effects of temperature change on the growth of Scots pine.
In 1964 to 1976 throughout the former USSR a series of provenance trials with Scots pine were established by State Forestry Committee (Shutayev and Giertich, 1998). The present paper is based on the study of Scots pine trees from the provenance trials established in southern taiga and forest-steppe, Central Siberia (58 0 N, 97 0 E and 57 0 N, 93 0 E).
In 1964 and 1974 the Laboratory of Forest Genetics and Breeding of the Institute of Forest led by A.I. Iroshnikov, L.I. Milyutin and N.A. Kuzmina raised seedlings in Krasnoyarsk forest-steppe and Boguchany southern taiga. Outplanting was carried out with 3-year-old plants. The forest-steppe plantation lies on a flat area of 0.25 hectares for each provenance, on the sod-podzol farmland; and southern taiga plantation lies on a large flat area of 9 hectares, on the site of a former open pine forest with dark gray forest soil. The seedlings were planted in rows 1.5×0.7 m apart. Details of the establishment and design of the tests have been described more recently by A.I. Iroshnikov (1977) and N.A. Kuzmina (1999).
We selected the biggest trees in the plots, based on DBH to minimize the influence of competition, and the biggest trees mostly contain climatic signal. 405 increment cores from 16 pine provenances were collected from southern taiga plantation and 292 increment cores from 12 pine provenances were from forest-steppe plantation. The seed sources were distributed across a wide climatic range (Fig. 1). For each provenance, 20-25 trees were sampled.
Cores were analyzed with a DENDRO-2003 densitometer. Schweingruber (1988) and Eschbach et al. (1995) have given detailed descriptions of the technique. Tree-ring width, earlywood width, latewood width and percentage latewood (radial growth chronologies), minimum and maximum densities, density of early- and latewood (density chronologies) were measured and crossdated. Chronologies of all eight tree-ring characteristics were obtained for each tree (individual series) and for each provenance by averaging these individual series (mean series) and showed interannual (from year to year) weather-related reactions and age trends. To exclude an age trend tree-ring chronologies were standardized using linear and non-linear functions, and then, indices were calculated (Cook et al. 1990). In previous studies cluster analysis grouped the provenances within each provenance trials into three groups (Savva et al. 2002, Savva et al. (sent to editors)). The first group consisted from the provenances originated geographically close to a test site; the second one consisted from remote provenances; and the third one consisted from northernmost provenances (forest-tundra and northern taiga). Main climatic factors influenced tree-ring formation of the provenances were extracted by averaging the indices data within each cluster of the provenances, and then, by calculating the coefficients of correlation with mean monthly data of temperature and precipitation obtained from the weather stations located alongside the provenance trials (Boguchany and Suhobuzimo regions). Climatic signals for each provenance were evaluated and compared by the coefficients of sensitivity to climatic factors (Schweingruber 1988).
The response of the provenances related to their geographical origin was quantitatively evaluated by calculation of the normalized Euclidean distances from the local provenances (Boguchany and Kazachinsk respectively). We used the coefficients of synchronicity and correlations between the local provenance and other provenances for calculating these distances (Shiyatov 1986; Schweingruber 1988, Aivazyan et al. 1987).
Cluster analysis applied earlier (Savva et al., 2002; Savva et al. (sent to editors)) distinguished the provenances in southern taiga in a following way. The first group included the following provenances: Severo-Yeniseysk, Boguchany, Revda, Kurovskoye, Svobodnyi, Pryazha, Nikol'sk and Zaudinsk; the second group included Minusinsk, Turukhansk, Avzyan, Yakutsk, Balgazyn, Ayan; and the Pechenga provenance provided an example of a unique provenance from the forest-tundra ecotone. The provenances planted in forest-steppe are distinguished in the following way. The first group included the following provenances: Djida, Tygda, Miass, Sverdlovsk, Kazachinsk, Ulan-Ude, Perm and Boguchany; the second group included Olekma, Leninogorsk and Lensk. The Sangarsk provenance provided an example of a unique provenance from the northern taiga. The response of the provenances to common climatic factors somewhat differs between the provenances planted in the southern taiga (Fig. 2). Increased temperature in April increases cell production and latewood portion of the provenances originated from the middle and southern taiga (cluster 1); warm spring hastens the growth of the southern provenances (cluster 2); but the response of the northern provenance is feebly marked, and a total cell production does not increase. At a latewood forming all provenances show similar response to climatic factors (Fig. 2). Increased precipitation in July contributes positively to radial growth of the provenances originated from poor moistening regions (steppe and forest-steppe provenances (cluster 2)). The northern provenance responds weakly to variations in temperature or precipitation than the other provenances. Latewood density correlates negatively with the precipitation in July for all provenances, except for the northern provenance. Climatic response of earlywood density is similar for the provenances, increased precipitation in April effects positively on earlywood density.
The response of the provenances to common climatic factors differs among the provenances planted in forest-steppe as well (Fig. 3). Tree-ring widths correlate highly with the average temperatures in April for all provenances. Increased precipitation in July forms large cells of a late wood promoting to an increase of a latewood portion of the provenances originated from the middle and mountain taigas (cluster 2). High summer temperatures influence positively latewood density for all provenances; the temperatures in May determine mainly the earlywood density of the extreme northern provenance. Earlywood density correlates negatively with the temperatures in June for all provenances and the precipitation in May for all except for the extreme northern provenance (cluster 3). Obtained results revealed the main climatic factors controlled the growth of provenances, and showed that the response differed slightly among the provenances within both plantations and a somewhat more for extreme northern provenances.
There are obvious differences between the provenances from both trials in a latewood formation. The coefficient of sensitivity of all latewood characteristics (latewood width, latewood portion, latewood and maximum densities) has a tendency to decrease with increase in the latitude of the seeds of provenances planted in southern taiga (-0.65>correlation coefficient R<-0.74) and forest-steppe (-0.51>R>-0.71). Obtained results are evidence for the existence of the genetically specified (related to geographical origin of seeds) response of the provenances to a changing environment.
Despite different response of the provenances to climatic change, the correlation and synchronicity coefficients showed high conformity in interannual variability of the provenances with the local provenance. In particular, the provenances planted in southern taiga correlate highly with the local provenance, Boguchany (with R values vary mostly between 0.7-0.9). The synchronicity coefficients for most of the provenances are not less than 0.7. The provenances planted in forest-steppe correlate highly with the local provenance, Kazachinsk (R>0.7, p<0.01), and all synchronicity coefficients being not less than 0.7 are classified as high (Shiyatov 1986). The normalized Euclidean distances were no more than 0.15 and 0.13 for all provenances from southern taiga and forest-steppe, respectively. The highest normalised Euclidean distance separated the local provenance from its remote provenances within both plantations (the Pechenga provenance from southern taiga plantation (d= 0.15); and the Sverdlovsk and the Perm provenances from forest-steppe plantation (d= 0.13)). Thus the studied provenances differ from the local provenance in interannual variability no more than 85%- 87% showing a prevailing influence of the local weather on a tree-ring formation.
Our results showed that climatic factors influenced tree-ring formation somewhat differed between different provenances from both provenance trials, especially for northernmost provenances. Significant differences between the provenances are related to a latewood formation. Trees from higher latitudes have adapted to maximally utilise the earliest available heat sum (Mikola 1962, Leikola 1969, Vaganov et al. 1999). Therefore the conditions of the second half of a growing season have less effect on radial growth characteristics. Whereas southern provenances use the energy resources (heat and light) effectively during the whole growing season. This result reflects the "memory" of the provenances about their geographical origin.
The measured tree-ring characteristics integrate the complex processes of wood formation such as cell division, radial extension and cell wall deposition (Larson 1994, Vaganov and Shashkin 2000). Revealed differences between the provenances (sensitivity to climatic factors, climatic response function) argue the existence of genetic control of wood formation if trees moved to new environment. Trees from higher latitudes keep the orientation towards accelerated growth at the beginning of a growing season, which is followed by a rapid transition to formation of latewood cells and deceleration of growth earlier, than in medium-latitude trees. This is completely consistent with the climatic response functions of trees at the polar timberline and northern taiga (Vaganov et al. 1999). However the correlation and synchronicity coefficients and normalized Euclidean distances showed that the genetic control of tree-ring formation is not strong (no more than 15% for the provenances from southern taiga plantation and 13% for the provenances from the forest-steppe plantation) which can be regarded as evidence for essential adaptation capacity of Scots pine to abrupt climatic change. It seems very interesting to continue this research in the future by studying response of other coniferous trees.
Tree-ring analysis allowed one to identify more suitable provenances for planting in the southern taiga and forest-steppe, Central Siberia. According to Zobel and van Buijtenen (1989), the main aim for tree breeding is reduction of within-tree variation. Assuming that simultaneously high values of ring width and wood density and low values of interannual variability are more desired traits of wood for tree breeding, the following provenances are more suitable for establishment of forest plantations: the provenances of the central Europe origins and the Zaudinsk provenance in the southern taiga; and Perm, Sverdolovsk, Miass and Olekma provenances in the forest-steppe, Central Siberia.
1. Northern provenances planted in the southern taiga and forest-steppe, Central Siberia retain their ability to use the energy resources (heat and light) of the first half of a growing season effectively.
2. Environmental mainly affects tree-ring formation in pine provenances planted in forest-steppe and southern taiga, Central Siberia (up to 85-87%).
The authors are grateful to Prof. F.H. Schweingruber, Prof. L.I. Milyutin and Dr. N.A. Kuzmina for helpful discussion. The research was conducted with financial support from the Russian Fund of Basic Researches, grant (02-04-49423).
Aivazyan, S.A., Bukhshtaber, V.M., Eniukov, I.S. and Meshalkin, L.D., 1989. [Applied statistics. A classification and reduction of dimensionality]. Moscow: Finance and Statistics, 230 p.(In Russian).
Barnett, J.R., 1981. Xylem Cell Development. Tunbridge Wells, Kent, Castle House Publications. 307 p.
Cook, E.R., Briffa, K.R., Shiyatov, S.G. and Mazepa, V.S., 1990. Tree-ring standardization and growth-trend estimation. In: (Cook E.R. and Kairiukstis L.A., eds.) Methods of Dendrochronology. Application in the Environmental Sciences. Dordrecht, Netherlands: Kluwer Acad. Publ. pp 104- 123.
Eschbach, W., Nogler, P., Schär, E. and Schweingruber, F.H., 1995. Technical advances in the Radiodensitometrical determination of wood density. Dendrochronologia, 13: 155-168.
Hulme, M., Sheard, N., and Markham, A., 1999. Global climate change scenarios. Climatic Research Unit, Norwich, UK. pp. 6.
Gindel, S., 1957. Acclimatization of exotic woody plants in Israel-the thory of phyto-plasticity. Mater. Végétabiles 2, N 2.
IPCC (Intergovernmental Panel on Climate Change), 2001. Climate Change 2001: The Scientific Basis. Working Group I contribution to the IPCC Third Assessment Report. (URL: http://www.ipcc.ch/).
Iroshnikov, A.I., 1977. [Provenance trials of conifers in southern Siberia] In: [Provenances trials and plantations of conifers in Siberia]. Novosibirsk, Nauka. pp. 3-117. (In Russian).
Kuzmina, N.A., 1999. [Growth characteristics of the Scots pine provenances in Priangar'ye.] Lesovedeniye [Russian Journal of Forest Research] 4: 23-29. (In Russian).
Larson, P.R., 1994. The vascular cambium. Development and structure. Berlin: Springer-Verlag, 725 p.
Leikola, M., 1969. The influence of environmental factors on the diameter growth of young trees. Acta.For.Fenn. 92: 1-4.
Matyas, C. and Yeatman, C., 1992. Effect of geographical transfer on growth and survival of jack pine (Pinus banksiana Lamb.) populations. Silvae Genetica 43(6): 370-376.
Mikola, P., 1962. Temperature and tree growth near the northern timberline. In: Tree Growth (T.T. Kozlowski, ed.), Ronald Press, New York. pp. 265-287.
Nekrasov, V.I., 1973. [The seed science basis of woody plants at introduction]. M.: Nauka, 279 p. (In Russian).
Savidge, R.A., 1996. Xylogenesis, genetic and environmental regulation. JAWA J. 17(3): 269-310.
Savva, Yu., Schweingruber, F.H., Milyutin, L.I. and Vaganov, E.A., 2002. Genetic and environmental signals in tree rings from different provenances of Pinus Sylvestris L., planted in the southern taiga, Central Siberia. Trees, 16: 313-324.
Savva, Yu., Vaganov, E.A. and Milyutin, L.I. Fitness assessment of Scots pine provenances by analysis of tree-ring characteristics. Forest ecology and management (sent to editors).
Sсhweingruber, F.H., 1988. Tree Rings: Basics and Applications of Dendrochronology. Dortrecht: Reidel Publ. 276 p.
Shiyatov, S.G., 1986. [Dendrochronology of the higher timber line on the Urals.] Moscow, Nauka, 136 p. (In Russian).
Shutyaev, A.M. and Giertych, M, 1998. Height growth variation in a comprehensive Eurasian provenance experiment of (Pinus sylvestris L.). Silvae Genetica, 46(6): 332-349.
Vaganov, E.A., Hughes, M.K., Kirdyanov, A.V., Schweingruber, F.H. and Silkin, P.P., 1999. Influence of snowfall and melt timing on tree growth in subarctic Eurasia. Nature 400: 149-151.
Vaganov, E.A. and Shashkin, A.V., 2000. [Tree-ring growth and structure of conifers]. Novosibirsk, Nauka, 232 p. (In Russian).
Watson, R.T., Zinyowera, M.C. and Moss, R.H. (Eds)., 1996. Climate Change 1995: Impacts, Adaptations and Mitigation of Climate Change: Scientific- Technical Analyses. Contribution of Working Group II to the second assessment report of the Intergovernmental Panel on Climate Change. Cambridge Univ. Press., 800 p.
Write, J.W., 1978. [Introduction to forest genetics]. Moscow, Lesnaya promyshlennost, 470 p. (In Russian).
Zobel, B.J. and van Buijtenen, J.P., 1989. Wood Variation: its Causes and Control. Springer -Verlag, Berlin, 363 p.
Legends to figures
Fig. 1. A map of the geographical origin of the Scots pine provenances tested in southern taiga (
) and forest-steppe (
), Central Siberia. Sizes of the objects are proportional to the Euclidean distances (varies from 0.8 to 0.15) to the local (Boguchany and Kazachinsk, arrows) provenances. 1.-Pechenga. 2-Pryazha. 3-Kurovskoye, 4-Nikol'sk, 5-Revda, 6-Avzyan, 7- Turukhansk, 8-Syevero-Yeniseysk, 9-Boguchany, 10-Minusinsk, 11-Balgazyn, 12-Zaudinsk, 13-Kyakhta, 14-Yakutsk, 15-Ayan, 16-Svobodniy; 17-Permsk, 18-Sverdlovsk, 19-Miass, 20-Boguchany, 21-Kazachinsk, 22-Lensk, 23-Olekma, 24-Tygda, 25-Ulan-Ude, 26-Dzhida, 27-Leninogorsk, 28-Sangarsk.
Fig. 2. The coefficients of correlation between indexed tree-ring series and mean monthly temperature and precipitation data for provenance test in southern taiga. TRW-tree-ring width, PLW-latewood percentage, MAX-latewood density, MIN-earlywood density.
Fig. 3. The coefficients of correlation between indexed tree-ring series and mean monthly temperature and precipitation data for provenance test in forest-steppe. For abbreviations, see Fig. 2.
Fig. 4. Indexed tree-ring width (TRW) and maximum density (MAX) series. Provenances are numbered according to the Fig. 1.
1 Institute of Forest SB RAS, Akademgorodok, Krasnoyarsk, 660036, Russia, e-mail: [email protected]