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Compared to arid regions, forests in humid regions can be more vulnerable to drought as they are not used to, and thus not adapted to, water stress. Therefore, it is vital to understand the drought responses of woodland species in humid areas. Xylem structures and functions of species growing in the humid regions are the key to their drought responses. Two Cupressaceae species (including three taxa: Sequoia sempervirens, Taxodium distichum and its variety Taxodium distichum var. imbricatum) grown in a mesic common garden were targeted, and their xylem hydraulic function (hydraulic conductivity, Ks; cavitation resistance, P50), anatomical structure (tracheid and pit structure), and mechanical support (wood density, WD; tracheid thickness-to-span ratio, Ttob) were measured. Likewise, we analyzed the differences in hydraulic function and anatomical structure of xylem in branches and roots, and the quantitative relationship between xylem water transport, anatomical structure, and mechanical support. Our results showed that roots had a higher hydraulic conductivity and a weaker cavitation resistance than branches. There was no safety–efficiency trade-off in the branches and roots within species. Tracheid mechanical support had a trade-off relationship with Ks or P50 (negative correlation appeared in branch Ks ~ WD and root Ks ~ Ttob of S. sempervirens, root P50 ~ Ttob of T. distichum var. imbricatum, and branch P50 ~ WD). There was no trade-off in anatomical structure, which led to no safety–efficiency trade-off in xylem function. Our results suggest that the two species exhibit both low efficiency and low safety in xylem, and that there is no safety–efficiency trade-off in branches and roots. The reason behind this is that the structural demand for high safety and high efficiency differs (i.e., the root Ks of S. sempervirens was strongly controlled by Dh; in contrast, the root P50 of S. sempervirens was strongly determined by tracheid density, N). Namely, the structural basis for a safety–efficiency trade-off does not exist and therefore trade-offs cannot be achieved.

Leaf veins are the continuation of twigs, and the hydraulic system of a leaf is part of, and the continuation of, the hydraulic architecture of a tree. Previous studies have demonstrated that the vessel diameter of the widest part at the tree base is tightly related to the total stem length of a tree. Here, we demonstrate that: the vessel diameter of the narrowest part at the distal end of the tree (the terminal twigs) is closely correlated to the leaf size for an angiosperm tree. Consequently, the basic feature of the hydraulic system of an angiosperm tree may be predicted by two simple parameters: the stem length (or tree height) and the leaf size, with the tree height predicting the size of the widest vessel at the tree base and the leaf size predicting the size of the narrowest vessel at the terminal trig. Namely, there is an inherent coordination between the leaf size and the hydraulic architecture of the angiosperm tree. As leaves are replacing themselves every year, their responses to climate are direct and immediate, while the woody part of a tree is there for years and more, and thus can only respond passively to climate change. This may cause a mismatch between the woody part and leaf part of the hydraulic system, and thus endanger the hydraulic coordination between leaves and the woody part.

The title centrosymmetric dinuclear NiII complex, [Ni(C14H8O4S)(C3H7NO)]n, was prepared via reaction of Ni(NO3)2·6H2O and thiosalicylic acid, with H2O and dimethylformamide (DMF) as the mixed solvent. The central NiII ion is five-coordinated by five O atoms from DMF and from the carboxylate groups of the organic ligand. The symmetry-related coordination polyhedra interlink into centrosymmetric dimeric units and these, in turn, are linked into infinite chains propagating parallel to [100].