Khan Attaullah, Gong Xue-Wei, Zhang Chi, Liu Shen-Si, Hao Guang-You
CAS Key Laboratory of Forest Ecology and Silviculture, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, People's Republic of China.
Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Liaoning Province, Shenyang, People's Republic of China.
Physiol Plant. 2025 Jan-Feb;177(1):e70075. doi: 10.1111/ppl.70075.
Populus tree species are commonly used for creating shelter forests in vast areas of northern China, at least partially due to their fast growth. However, they are facing severe problems of decline and mortality caused by drought. In contrast, tree species native to water-limited environments usually have slow growth and are currently not commonly used in afforestation, while these species are gaining more attention in forestry for their greater resilience to drought. In Horqin Sandy Land, we conducted a comparative analysis of xylem hydraulics and associated physiological traits between six Populus tree species and six tree species native to drought-prone areas. Compared to the native species, the Populus species exhibited significantly higher stem hydraulic conductivity but lower resistance to drought-induced xylem embolism than the native tree species. The observed interspecific variations and contrasts in xylem hydraulics between the two species groups were predominantly attributed to xylem anatomical characteristics at the pit level rather than at the tissue level. In line with the divergences in hydraulics, we found significantly lower intrinsic water use efficiency (WUE) in Populus than in the native species, suggesting that the two groups adopted relatively acquisitive and conservative water use strategies, respectively. The trade-off between hydraulic efficiency and safety, as well as that between hydraulic efficiency and WUE, underlies the contrasts in performance between Populus species and the native tree species, that is, fast growth of Populus species but high risk of hydraulic dysfunction when facing drought, and vice versa.
杨树品种在中国北方广大地区常用于营造防护林，至少部分原因是它们生长迅速。然而，它们正面临因干旱导致的严重衰退和死亡问题。相比之下，原产于水分受限环境的树种通常生长缓慢，目前在造林中并不常用，而这些树种因其对干旱具有更强的恢复力而在林业中受到越来越多的关注。在科尔沁沙地，我们对6种杨树品种和6种原产于干旱易发地区的树种进行了木质部水力特性及相关生理特征的比较分析。与本地树种相比，杨树品种表现出显著更高的茎水力导度，但对干旱诱导的木质部栓塞的抗性低于本地树种。两个树种组在木质部水力特性上观察到的种间差异和对比主要归因于纹孔水平而非组织水平的木质部解剖特征。与水力特性的差异一致，我们发现杨树的内在水分利用效率（WUE）显著低于本地树种，这表明两组分别采用了相对贪婪和保守的水分利用策略。水力效率与安全性之间的权衡，以及水力效率与WUE之间的权衡，是杨树品种与本地树种性能差异的基础，即杨树品种生长迅速但在面临干旱时水力功能失调的风险较高，反之亦然。
