Climatic Responses of Tree-Ring Widths of Larix Gmelinii on Contrasting North-Facing and South-Facing Slopes in Central Siberia

J Wood Sci (2007) 53:87–93 © The Japan Wood Research Society 2006 DOI 10.1007/s10086-006-0837-9 ORIGINAL ARTICLE Joni Kujansuu · Koh Yasue · Takayoshi Koike Anatoly P. Abaimov · Takuya Kajimoto · Takashi Takeda Morihiko Tokumoto · Yojiro Matsuura Climatic responses of tree-ring widths of Larix gmelinii on contrasting north-facing and south-facing slopes in central Siberia Received: April 11, 2006 / Accepted: August 4, 2006 / Published online: December 28, 2006 Abstract An analysis was performed on the climatic re- springtime play a significant role in the radial growth of L. sponses of the radial growth of Larix gmelinii (Rupr.) Rupr. gmelinii. The negative correlations between standard chro- on contrasting north-facing and south-facing slopes in Tura, nologies of tree-ring width and precipitation in the winter central Siberia. We developed chronologies of tree-ring and in May on the north-facing slope indicate that low- width for four plots, designated as north-upper, north- frequency fluctuations in snowfall have negative effects on lower, south-upper, and south-lower. Both residual and the radial growth. However, these effects vary and depend standard chronologies of tree-ring widths exhibited a sig- on the microscale topography. nificant positive correlation with temperature from the end of May until early June in all four plots. The chronologies of Key words Larix gmelinii · Siberia · Permafrost · Climatic ring width did not reveal any major difference in the re- response · Tree-ring width sponse to temperature among the four plots. The standard chronologies of ring widths on the north-facing slope were negatively correlated with precipitation during the winter (October–April) and in early and mid-May, whereas the Introduction residual chronologies did not reveal clear relationships with precipitation during the winter and May. The significant The Siberian boreal forest, which is the largest terrestrial correlation between ring width and temperature from the carbon pool in the northern hemisphere, has the greatest end of May until early June indicates that temperatures in potential affect the global storage of carbon.1 For the most part, Siberian boreal forests are dominated by deciduous Larix species, which possess about 35% of the total carbon J. Kujansuu storage of the forests of Russia.2,3 Thus, the responses of United Graduate School of Agricultural Science, Gifu University, radial growth of larch trees to climatic change can Gifu 501-1193, Japan significantly influence the carbon pool of the Eurasian J. Kujansuu · K. Yasue (*) · T. Takeda · M. Tokumoto boreal forest. Department of Forest Science, Faculty of Agriculture, Shinshu University, Minami-Minowa, Nagano 399-4598, Japan At the northern timberline in the continuous permafrost Tel. +81-265-77-1510; Fax +81-265-77-1510 region in the Siberian subarctic, the ring widths of conifer- e-mail: [email protected] ous species are positively influenced by temperatures in 4 T. Koike June–July. Similar results have been obtained for Larix Faculty of Agriculture, Hokkaido University, Sapporo 060-0811, species (Larix sibirica, Larix gmelinii, and Larix cajanderi) Japan in the same region.5,6 In addition, Kirdyanov et al.6 postu- A.P. Abaimov lated that the date of snowmelt is a significant factor in the Sukachev Institute of Forest, Siberian Branch, Russian Academy of control of the initiation of radial growth of larch trees. At Science, Academgorodok, Krasnoyarsk 660036, Russia present, published information on the responses of Siberian T. Kajimoto larch trees to climate remains limited and little research has Kyushu Research Center, Forestry and Forest Products Research Institute, Kumamoto 860-0862, Japan been done on mechanisms responsible for the responses of tree-ring parameters to climate variables under varying Y. Matsuura Forestry and Forest Products Research Institute, Tsukuba 305-8687, growth conditions. Japan Topographical features of the landscape, such as slope 7 exposure, create microclimatic differences. Kirchhefer re- Part of this report was presented at the 55th Annual Meeting of the ported differences in the responses of tree-ring widths of Japan Wood Society, March 2005, Kyoto Pinus sylvestris to temperature and precipitation between 88 South-facing North-facing slope slope 148 55cm 4 8 cm Fig. 2. Schematic representation of the study site. The depths of the active layers on the two slopes, as indicated by the dotted line, are taken from Koike et al.8 Horizontal dotted lines indicate the borders of the upper and lower plots climate of the region is continental, with very cold winters Fig. 1. Geographical location of the study site indicated by the filled and relatively warm summers. The mean annual tempera- square. The map shows the distribution of the permafrost in the North- ture is −7.6°C, as determined at the Tura Meteorological ern Hemisphere and the range of distribution of Larix species in Station (Russian Research Institute of Hydrometeoro- Eurasia. Redrawn from Environmental Defense Fund20 and Abaimov et al.3 logical Information – World Data Center, RIHMI-WDC; http://www.meteo.ru/data/emdata.htm). The mean temperature in January is −36.5°C and that in July is 17.3°C. The mean annual precipitation is 380mm. the north-facing and south-facing slopes in an area north of We chose contrasting north-facing and south-facing the Arctic Circle in Norway. Koike et al.8 reported differ- slopes that are divided by a small stream (Fig. 2). The study ences in shoot morphology, rates of photosynthesis, and site is located about 10km northwest from Tura Meteoro- nutrient conditions of L. gmelinii in active soil layers of logical Station. The difference of elevation between river- different depths on contrasting north-facing and south-fac- bed and hilltop is approximately 30m, and the gradient ing slopes in central Siberia. Because of changes in the of the slope is 18° on the south-facing slope and varies active layer that might be expected to occur as a result of between 8° and 18° on the north-facing slope. The south- possible future changes in climate, it is important to identify facing slope is almost entirely occupied by Larix gmelinii, the responses of the radial growth of larch trees to climate whereas the north-facing slope is dominated by L. gmelinii variables under different microsite conditions with varying with a small proportion of Picea obovata.8 The forest stand active layers of permafrost. became established after a forest fire that occurred in the The purpose of the present study is to clarify the influ- early 1800s. The forest stand on the north-facing slope ence of temperature and precipitation on tree-ring widths of is unevenly aged, caused by survivors of the forest fire, Larix gmelinii (Rupr.) Rupr. growing on contrasting north- whereas the south-facing slope seems to be evenly aged. facing and south-facing slopes in central Siberia. A com- The depth of the active soil layer differs markedly between parison of the growth responses of tree-ring widths to the two slopes, being 148 ± 5cm on the south-facing slope climate variables between the two slopes should help to and only 45 ± 8cm on the north-facing slope in the summer clarify the impact of temperature and precipitation on the of 1997.8 We divided the study site into four plots (approxi- radial growth of larch trees growing under specific condi- mately 40 × 20m each) by dividing the north-facing and tions with microscale variations and to identify mechanisms south-facing slopes into upper and lower parts (abbreviated that control radial growth. as NU, NL, SU and SL), because we assumed that differences in soil moisture between the upper and lower parts of the slopes might arise. We chose to examine 30 dominant specimens of L. gmelinii per plot. Materials and methods Study site and sample trees Development of chronologies The study site is located in the Tura Experiment Forest We extracted two increment cores of 5mm in diameter from (64°19′N, 100°13′E; 200masl) of the Sukachev Institute of each sample tree at breast height and parallel to the contour Forest (Siberian Branch, Russian Academy of Science, of the slope. This procedure provided 60 cores per plot, Russia), on the Central Siberian Plateau, close to the west- giving a total of 240 cores; these were smoothed with fine ern edge of a region of continuous permafrost (Fig. 1). The sandpaper and a razor blade. The tree-ring widths were 89 measured to 0.01mm precision under a stereomicroscope Observations on snowmelt and leaf development (MZ6; Leica, Solms, Germany) with a system for tree-ring measurement from Velmex (Bloomfield, NY, USA). The For observations of the timing of the snowmelt on the con- series of tree-ring widths were cross-dated visually by using trasting slopes in the spring of 2004, we installed an auto- skeleton plot procedures and confirmed by a statistical matic camera (KADEC21-EYE; Kona Systems, Sapporo, method to ensure that the correct date was assigned to each Japan) at the study site in the autumn of 2003. The snow annual ring.9 Statistical cross-dating was performed with the cover on the ground on both slopes was visible in each COFECHA program.10 Some core samples in which there photograph. One image was taken each day at noon. was evidence of the extensive formation of reaction wood Leaf initiation and expansion stages were observed visu- were excluded because of cross-dating difficulties. The se- ally in the spring of 2004, from 29 May to 14 June. Visual ries of tree-ring measurements were standardized by fitting observations were made at four different observation sites smoothing splines with a 50% frequency-response cutoff of located within 30km of the study site during the fieldwork 80 years to eliminate growth trends such as an age-related period.

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