Climatic factors affecting radial growth of Betula ermanii and Betula platypylla in Kamchatka Jiri Dolez ˇ al, Hiroaki Ishii, Toma ´s ˇ Kyncl, Koichi Takahashi, Valentina P. Vetrova, Kosuke Homma, Akihiro Sumida, and Toshihiko Hara Abstract: Radial growth responses to climate were studied in two species of birch broadly distributed across Kamchatka Peninsula. Wood cores were obtained in different locations and environments, from upper to lower treelines, and from wet maritime sites at the Pacific to the subcontinental interior of the peninsula. Response functions were calculated using the four longest meteorological records (1920s–2000) in Kamchatka. In Betula ermanii Cham., the dominant species in moun- tains and maritime woodlands, ring width in high-elevation (500–600 m) trees increased with warm and less rainy June and July and decreased with rainy/snowy cool weather during the prior September and October. Radial growth in B. erma- nii low-elevation trees increased with higher winter precipitation, suggesting that water from melting snow prevents water stress and possibly desiccation in low-elevation trees. In Betula platyphylla Sukaczev, a common taiga species in interior Kamchatka, low summer temperatures limited growth at its upper distributional limit (300–350 m) and in cool, wet sites dominated by Picea ajanensis Lindl. et Gord. On drier sites dominated by Larix cajanderii Mayr., growth was limited by warm April and dry June weather. Variable responses along elevation–continentality gradients reinforce the necessity of a site-dependent differentiation for the assessment of impacts of climate change on species performance and geographic range shifts. Re ´sume ´: Les re ´ponses de la croissance radiale au climat ont e ´te ´e ´tudie ´es chez deux espe `ces de bouleau distribue ´es sur l’ensemble de la pe ´ninsule de Kamchatka. Des carottes de bois ont e ´te ´ pre ´leve ´es a ` diffe ´rents endroits et dans diffe ´rents en- vironnements, de la limite supe ´rieure a ` la limite infe ´rieure des arbres et sur des stations maritimes humides du co ˆte ´ du Pa- cifique jusqu’a ` l’inte ´rieur subcontinental de la pe ´ninsule. Des fonctions de re ´ponse ont e ´te ´ calcule ´es en utilisant les quatre plus longs releve ´s me ´te ´orologiques (anne ´es 1920 a ` 2000) du Kamchatka. Chez Betula ermanii Cham., l’espe `ce dominante dans les montagnes et les boise ´s maritimes, la largeur des cernes annuels chez les arbres situe ´s a ` haute altitude (500– 600 m) augmentait avec le temps chaud et moins pluvieux en juin et juillet; elle diminuait avec le temps frais et pluvieux ou neigeux durant les mois de septembre et octobre pre ´ce ´dents. La croissance radiale des tiges de B. ermanii situe ´es a ` basse altitude augmentait avec la quantite ´ de pre ´cipitations hivernales, indiquant que l’eau provenant de la fonte des neiges pre ´vient les stress hydriques et possiblement la dessiccation chez les arbres situe ´s a ` basse altitude. Chez Betula platyphylla Sukaczev, une espe `ce commune dans la taı ¨ga a ` l’inte ´rieur du Kamchatka, les tempe ´ratures basses durant l’e ´te ´ limitaient la croissance a ` sa limite supe ´rieure de distribution (300–350 m) et sur les stations fraı ˆches et humides domine ´es par Picea ajanensis Lindl. et Gord. Sur les stations plus se `ches domine ´es par Larix cajanderii Mayr., la croissance e ´tait limite ´e par le temps chaud en avril et sec en juin. Les re ´ponses variables le long de gradients d’altitude ou de continentalite ´ renforcent la ne ´cessite ´ d’une diffe ´renciation base ´e sur le site pour l’e ´valuation des impacts des changements climatiques sur la perfor- mance des espe `ces et la modification de leur e ´tendue ge ´ographique. [Traduit par la Re ´daction] Received 10 February 2009. Accepted 23 September 2009. Published on the NRC Research Press Web site at cjfr.nrc.ca on 30 January 2010. J. Dolez ˇal. 1 Institute of Botany, Czech Academy of Sciences, Dukelska ´ 135, CZ-379 82 Trˇebon ˇ, Czech Republic; Department of Botany, Faculty of Science, University of South Bohemia, Na Zlate ´ stoce 1, 370 05 C ˇ eske ´ Bude ˇjovice, Czech Republic. H. Ishii. Institute of Low Temperature Science, Hokkaido University, Kita-ku, Sapporo 060-0819, Japan; Kobe University, Graduate School of Agricultural Science, Division of Forest, Resources, Kobe, Hyogo 6578501, Japan. T. Kyncl. Laboratory of Dendrochronology, Elia ´s ˇova 37, CZ-616 00 Brno and Institute of Botany, Czech Academy of Sciences, Za ´mek 1, CZ-252 43 Pru ˚honice, Czech Republic. K. Takahashi. Department of Biology, Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto 390-8621, Japan. V.P. Vetrova. Laboratory of Plant Ecology, Kamchatka Branch of Pacific Institute of Geography, Far-Eastern Branch of Russian Academy of Sciences, Rybakov pr. 19a, Petropavlovsk-Kamchatsky 683024. K. Homma. Field Center for Sustainable Agriculture and Forestry, Faculty of Agriculture, Niigata University, 94-2 Koda, Sado, Niigata 952-2206, Japan. A. Sumida and T. Hara. Institute of Low Temperature Science, Hokkaido University, Kita-ku, Sapporo 060-0819, Japan. 1 Corresponding author (e-mail: jiriddolezal@gmail.com). 273 Can. J. For. Res. 40: 273–285 (2010) doi:10.1139/X09-179 Published by NRC Research Press