Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China.
Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.
Tree Physiol. 2019 May 1;39(5):747-754. doi: 10.1093/treephys/tpy151.
Present-day global warming is occurring faster at higher elevations. Although there is much information regarding the divergent responses of tree growth to climate change, the altitudinal patterns of species-specific xylogenesis remains poorly understood. We investigated the xylogenesis of balsam fir (Abies balsamea Mill.) and black spruce (Picea mariana Mill. B.S.P.) at two elevations in Quebec (Canada). The number of enlarging and mature cells of the developing tree ring were counted on microcores collected weekly between 2011 and 2014. At the lower site, the growth pattern and duration of xylogenesis were similar between species. No difference in responses to temperature and solar radiation between species was observed. At the higher site, however, cell production was higher and lasted longer in balsam fir than black spruce. Furthermore, the xylem growth of balsam fir had a stronger response to temperature and solar radiation than black spruce. These findings demonstrate the contrasting strategies of wood formation of the two species, with black spruce being more conservative than balsam fir. Our study provides evidence that sympatric species can have species-specific growth dynamics and site-specific responses to the local environment. Predictions of tree growth under a changing environment require the incorporation of species-specific growth strategies.
当今全球变暖在高海拔地区发生得更快。尽管有很多关于树木生长对气候变化的不同反应的信息，但物种特有的木质部形成的海拔模式仍知之甚少。我们在魁北克（加拿大）的两个海拔高度调查了香脂冷杉（Abies balsamea Mill.）和黑云杉（Picea mariana Mill. B.S.P.）的木质部形成。在 2011 年至 2014 年期间每周收集微芯，对其进行计数，以确定发育树轮中扩大和成熟细胞的数量。在较低的地点，两种物种的生长模式和木质部形成的持续时间相似。未观察到两种物种对温度和太阳辐射的反应存在差异。然而，在较高的地点，冷杉的细胞产量更高，持续时间更长。此外，冷杉的木质部生长对温度和太阳辐射的反应比黑云杉更强。这些发现表明，这两个物种的木材形成策略截然不同，黑云杉比冷杉更保守。我们的研究提供了证据表明，同域物种可以具有特定于物种的生长动态和对当地环境的特定于地点的反应。在不断变化的环境下预测树木的生长需要结合物种特有的生长策略。
