Increased water‐use efficiency translates into contrasting growth patterns of Scots pine and sessile oak at their southern distribution limits
Increased water‐use efficiency translates into contrasting growth patterns of Scots pine and sessile oak at their southern distribution limits
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DOI：
10.1111/gcb.13937
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发表时间：
2018-03
影响因子：
11.6
通讯作者：
E. Martínez‐Sancho;I. Dorado-Liñán;E. Gutiérrez Merino;M. Matiu;G. Helle;I. Heinrich;A. Menzel
中科院分区：
文献类型：
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作者：
E. Martínez‐Sancho;I. Dorado-Liñán;E. Gutiérrez Merino;M. Matiu;G. Helle;I. Heinrich;A. Menzel
在森林中，大气CO2浓度（Ca）的增加与树木生长和内在水分利用效率（iWUE）的增强有关。然而，在干旱易发地区，如地中海盆地，目前尚不清楚这种“施肥”效应在多大程度上可以补偿干旱引起的生长减少。研究了5种苏格兰松（Pinus sylvestris L.）和5种无柄栎（Quercus petaea (Matt.)）的生长和生理反应。（Liebl.），利用每年的树轮宽度和δ13C数据来跟踪生态生理过程，在1960-2012年期间位于欧洲最南端的分布极限。结果表明，10个天然林分叶片细胞间CO2浓度（Ci）均显著升高，iWUE随之显著升高。在不同的理论气体交换情景中发现了不同的趋势，作为对Ca增加的响应：一般来说，除了在Ci保持不变的最干燥地点的树木外，Ci倾向于与Ca成比例地增加。水分有效度较高的栎树立地Ci的增加速率与Ca相当。利用iWUE和气候变量在立地水平拟合的多元线性模型来预测基础面积增量（BAI），松树（31.9% ~ 71.4%）比栎树林（15.8% ~ 46.8%）更能解释树木生长。iWUE与松木生长呈负相关，而对栎树生长的影响在不同立地存在差异。西部和中部栎林的生长与iWUE呈负相关，而最东部栎林的BAI与iWUE呈正相关。因此，部分扁豆林分可能部分受益于钙升高的“施肥”效应，而柽柳林分由于气孔严格关闭而没有受益于iWUE的增加，因此在各立地表现出普遍的生长减少。此外，BAI和iWUE的年际变化在地中海地区表现出地理极性。
In forests, the increase in atmospheric CO2 concentrations (Ca) has been related to enhanced tree growth and intrinsic water‐use efficiency (iWUE). However, in drought‐prone areas such as the Mediterranean Basin, it is not yet clear to what extent this “fertilizing” effect may compensate for drought‐induced growth reduction. We investigated tree growth and physiological responses at five Scots pine (Pinus sylvestris L.) and five sessile oak (Quercus petraea (Matt.) Liebl.) sites located at their southernmost distribution limits in Europe for the period 1960–2012 using annually resolved tree‐ring width and δ13C data to track ecophysiological processes. Results indicated that all 10 natural stands significantly increased their leaf intercellular CO2 concentration (Ci), and consequently iWUE. Different trends in the theoretical gas‐exchange scenarios as a response to increasing Ca were found: generally, Ci tended to increase proportionally to Ca, except for trees at the driest sites in which Ci remained constant. Ci from the oak sites displaying higher water availability tended to increase at a comparable rate to Ca. Multiple linear models fitted at site level to predict basal area increment (BAI) using iWUE and climatic variables better explained tree growth in pines (31.9%–71.4%) than in oak stands (15.8%–46.8%). iWUE was negatively linked to pine growth, whereas its effect on growth of oak differed across sites. Tree growth in the western and central oak stands was negatively related to iWUE, whereas BAI from the easternmost stand was positively associated with iWUE. Thus, some Q. petraea stands might have partially benefited from the “fertilizing” effect of rising Ca, whereas P. sylvestris stands due to their strict closure of stomata did not profit from increased iWUE and consequently showed in general growth reductions across sites. Additionally, the inter‐annual variability of BAI and iWUE displayed a geographical polarity in the Mediterranean.