Gruber A, Wieser G, Oberhuber W
Institute of Botany, University of Innsbruck, 6020 Innsbruck, Austria.
Tree Physiol. 2009 May;29(5):641-9. doi: 10.1093/treephys/tpp001. Epub 2009 Feb 2.
The relationship between stem CO(2) efflux (E(S)), cambial activity and xylem production in Pinus cembra L. was determined at the timberline (1950 m a.s.l.) of the Central Austrian Alps, for 1 year. The E(S) was measured continuously from June 2006 to August 2007 using an infrared gas-analysis system. Cambial activity and xylem production were determined by repeated microcore sampling of the developing tree ring, and radial increment was monitored using automated point dendrometers. Besides temperature, the number of living tracheids and cambial cells was predominantly responsible for E(S), and E(S) normalized to 10 degrees C (E(S10)) was significantly correlated to the number of living cells throughout the year (r(2) = 0.574; P < 0.001). However, elevated E(S) and missing correlation between E(S10) and xylem production were detected during cambial reactivation in April and during transition from active phase to rest, which occurred in August and lasted until early September. Results of this study indicate that (i) during seasonal variations in cambial activity, nonlinearity between E(S) and xylem production occurs and (ii) elevated metabolic activity during transition stages in the cambial active-dormancy cycle influences the carbon budget of P. cembra. Daily radial stem increment was primarily influenced by the number of enlarging cells and was not correlated to E(S).
在奥地利中部阿尔卑斯山海拔1950米的树线处，对瑞士石松的茎干二氧化碳通量（E(S)）、形成层活动和木质部生成之间的关系进行了为期1年的测定。使用红外气体分析系统从2006年6月至2007年8月连续测量E(S)。通过对发育中的年轮进行重复微芯取样来确定形成层活动和木质部生成，并使用自动点式测树仪监测径向生长量。除温度外，活管胞和形成层细胞的数量是E(S)的主要影响因素，全年归一化至10℃的E(S)（E(S10)）与活细胞数量显著相关（r(2)=0.574；P<0.001）。然而，在4月形成层重新激活期间以及8月至9月初从活跃期过渡到静止期时，检测到E(S)升高且E(S10)与木质部生成之间缺乏相关性。本研究结果表明：（i）在形成层活动的季节变化期间，E(S)与木质部生成之间存在非线性关系；（ii）形成层活跃-休眠周期过渡阶段的代谢活动增强会影响瑞士石松的碳收支。茎干每日径向生长量主要受正在膨大的细胞数量影响，与E(S)无关。
