Xylem hydraulic adjustment and growth response of Quercus canariensis Willd. to climatic variability
Xylem hydraulic adjustment and growth response of Quercus canariensis Willd. to climatic variability
复制标题
DOI：
10.1093/treephys/tps026
复制
发表时间：
2012-04-01
期刊：
影响因子：
4
通讯作者：
Canellas, I.
中科院分区：
文献类型：
--
作者：
Gea-Izquierdo, G.;Fonti, P.;Canellas, I.
全球变化挑战森林在物种分布限制下的适应性。我们研究了环孔栎。木质部特征来分析它们如何适应气候的时空变化。沿着海拔样线对树木进行采样，并建立了径向生长（年轮宽度（RW））和几个早材导管（EV）特征的年度时间序列，以分析它们与气候的关系。这些树木在短期内对随着海拔降低和气候变化而增加的水限制做出了反应，但分析表明，在过去 30 年里，木质部并没有适应长期温度升高。植物对气候变化的调整通过不同的木质部性状以不同但互补的方式表达。在低海拔地区，树木与水分胁迫指数表现出更高的相关性，并且树木通过减少径向生长和水力直径（D-H）但增加血管密度（DV）来适应低海拔地区更干旱的条件。不同海拔树木的平均电势电导率 (K-H) 相似。然而，木质部性状的树间差异高于海拔之间的差异，表明个体遗传特征或微场地条件的强烈影响。在 D-H 较大、特别是血管线密度 (DVl) 较大的年份，树木表现出较高的 RW，但部分地，RW 中表达的气候信号与 EV 中的气候信号不同。在寒冷的冬季和潮湿的年份之后，树木会产生更大的 D-H。年轮宽度对秋季和春季的湿冷天气有正向响应，而DV和K-H对气候的响应总体与RW相反。这些关系可能表达了冬季高呼吸速率对明年春季用于生产电动汽车的碳库的负面影响，以及树木可用水量的总体积极影响。我们的结果表明，近几十年来，不同地点的树木能够根据气候变化和温度升高调整其水力结构，协调几个互补的特性。尽管如此，仍应监测它们是否能够成功适应未来水资源压力加剧的气候情景。
Global change challenges forest adaptability at the distributional limit of species. We studied ring-porous Quercus canariensis Willd. xylem traits to analyze how they adjust to spatio-temporal variability in climate. Trees were sampled along altitudinal transects, and annual time series of radial growth (ring width (RW)) and several earlywood vessel (EV) traits were built to analyze their relationships with climate. The trees responded to increasing water constraints with decreasing altitude and changes in climate in the short term but the analyses showed that xylem did not acclimate in response to long-term temperature increase during the past 30 years. The plants' adjustment to climate variability was expressed in a different but complementary manner by the different xylem traits. At low elevations, trees exhibited higher correlations with water stress indices and trees acclimated to more xeric conditions at low elevations by reducing radial growth and hydraulic diameter (D-H) but increasing the density of vessels (DV). Average potential conductivity (K-H) was similar for trees at different altitudes. However, inter-tree differences in xylem traits were higher than those between altitudes, suggesting a strong influence of individual genetic features or micro-site conditions. Trees exhibited higher RW those years with larger D-H and particularly the linear density of vessels (DVl), but partly, climatic signals expressed in RW differed from those in EVs. Trees produced larger D-H after cold winters and wet years. Ring width responded positively to wet and cool weather in fall and spring, whereas the response to climate of DV and K-H was generally opposite to that of RW. These relationships likely expressed the negative impact of high respiration rates in winter on the carbon pools used to produce the EVs in the next spring and the overall positive influence of water availability for trees. Our results showed that trees at different sites were able to adjust their hydraulic architecture to climatic variability and temperature increase during recent decades coordinating several complementary traits. Nonetheless, it should be monitored whether they will succeed to acclimate to future climatic scenarios of increasing water stress.