Xylem hydraulics and non-structural carbohydrate contents in 15 temperate tree species

In humid temperate forests, the occurrence of frequent freeze-thaw cycles (FTC) is a main factor limiting tree growth, as xylem embolism induced by FTC poses a serious threat to the hydraulic integrity of trees. A high resilience to hydraulic dysfunction involves the enhancement of embolism resistance and/or extra non-structural carbohydrate (NSC) inputs for restoration of an impaired hydraulic system. However, potentially negative implications of such NSC allocation on tree growth have not yet been explored. At a temperate forest site of northeast China, we studied xylem hydraulics and NSC contents in relation to winter embolism resilience in 15 sympatric broadleaf tree species belonging to three genera with relatively high species richness, 6 Acer species, 5 Betula species and 4 Populus species. Acer and Betula species had higher soluble sugar contents in the dormant season and indeed had higher hydraulic resilience to FTC induced embolism but slower stem growth. Populus species...在湿润温带森林中，频繁发生的冻融循环（freeze-thaw cycles, FTC）是限制树木生长的主要因素之一，因冻融循环诱导产生的木质部栓塞会对树木的水分运输完整性构成严重威胁。树木对水分运输功能障碍的高耐受性，依赖于增强栓塞抗性，或是额外投入非结构性碳水化合物（non-structural carbohydrate, NSC）以修复受损的水分运输系统。然而，这类非结构性碳水化合物分配策略对树木生长可能产生的负面影响，目前尚未得到探究。 本研究在中国东北一处温带森林样地开展，针对15个同域阔叶树种展开了木质部水力学特性与非结构性碳水化合物含量的相关研究，以探究其与冬季栓塞耐受性的关联。该15个树种分属3个物种丰富度较高的属，包括6种槭属（Acer）植物、5种桦木属（Betula）植物以及4种杨属（Populus）植物。 槭属与桦木属树种在休眠期的可溶性糖含量更高，且对冻融循环诱导的栓塞具有更强的水分运输耐受性，但茎干生长速率较慢。杨属（Populus）树种...