Islam Mahmuda, Rahman Mizanur, Bräuning Achim
Department of Geography and Geosciences, Institute of Geography, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany.
Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet, Bangladesh.
Front Plant Sci. 2018 Dec 4;9:1761. doi: 10.3389/fpls.2018.01761. eCollection 2018.
Xylem hydraulic adjustment to global climatic changes was reported from temperate, boreal, and Mediterranean tree species. Yet, the long-term hydraulic adjustment in tropical tree species has not been studied so far. Here we developed the first standard chronologies of three hydraulic trait variables for three South Asian moist forest tree species to analyze their long-term hydraulic responses to changing climate. Based on wood anatomical measurements, we calculated Hagen-Poiseuille hydraulically weighted vessel diameter (D), potential specific hydraulic conductivity (K), and vulnerability index (V) and developed standard chronologies of these variables for , and which are different in their xylem structure, wood density, shade tolerance, growth rates, and habitat preferences. Bootstrap correlation analysis revealed that vapor pressure deficit (VPD) strongly positively influenced the xylem water transport capacity in , whereas was affected by both temperature and precipitation. The hydraulic conductivity of was mainly affected by temperature. Different adjustment strategies were observed among the species, probably due to the differences in life history strategies and xylem properties. No positive relationship of conductivity and radial growth was found, but a trade-off between hydraulic safety and efficiency was observed in all studied species.
据报道，温带、寒带和地中海地区的树种会对全球气候变化进行木质部水力调节。然而，目前尚未对热带树种的长期水力调节进行研究。在此，我们为三种南亚湿润森林树种编制了首批三个水力性状变量的标准年表，以分析它们对气候变化的长期水力响应。基于木材解剖学测量，我们计算了哈根 - 泊肃叶水力加权导管直径（D）、潜在比水力导率（K）和脆弱性指数（V），并为三种在木质部结构、木材密度、耐荫性、生长速率和栖息地偏好方面存在差异的树种编制了这些变量的标准年表。自展相关分析表明，水汽压亏缺（VPD）对第一种树种的木质部水分运输能力有强烈的正向影响，而第二种树种受温度和降水的共同影响。第三种树种的水力导率主要受温度影响。在这些树种中观察到了不同的调节策略，这可能是由于生活史策略和木质部特性的差异所致。未发现导率与径向生长之间存在正相关关系，但在所有研究树种中均观察到了水力安全性与效率之间的权衡。
