Nitrogen and phosphorus allocation in leaves, twigs, and fine roots across 49 temperate, subtropical and tropical tree species: a hierarchical pattern
Nitrogen and phosphorus allocation in leaves, twigs, and fine roots across 49 temperate, subtropical and tropical tree species: a hierarchical pattern
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DOI：
10.1111/j.1365-2435.2009.01603.x
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发表时间：
2010-02-01
影响因子：
5.2
通讯作者：
Liu, Hongyan
中科院分区：
文献类型：
--
作者：
Li, Ang;Guo, Dali;Liu, Hongyan
P > 1。分层分支是树的基本特征。了解树木结构如何与组织养分浓度、代谢率和生命周期相关联，对于预测呼吸、模块转换和有机物分解等生态系统过程非常重要。本文通过分析49种乔木（包括21种温带被子植物、6种温带裸子植物和22种亚热带被子植物）叶片、枝条前3阶和根系前5阶的氮、磷、氮、磷比，研究了树木地上、地下分支系统的枝阶-营养关系。各树种的组织[N]和[P]随枝级和根级的增加呈线性下降。根序与根[N]的线性回归斜率在温带和亚热带被子植物之间是相同的，但被子植物比裸子植物更陡。相比之下，根序-[P]关系在不同的生物群落之间存在差异，而在不同的系统发育类群之间没有差异，这可能是由于亚热带土壤中P效价明显较低。此外，组织[N]和[P]在连续的茎和根枝顺序之间的变化幅度在分枝水平上不是恒定的。在所有细根阶中，一级根尖的[N]、[P]和N: P比值与叶片最接近。这些结果表明，土壤表层和地下表层存在普遍的逆序营养关系，尽管这种关系的具体模式在N和P之间以及在物种群之间有所不同。此外，在细根协会的所有根目中，根尖与叶片的养分浓度最接近。本文提出的顺序-营养关系促进了我们对树木功能模块构建的理解，并为模拟森林生态系统中组织化学调节过程（如呼吸和分解）提供了基础。
P>1. Hierarchical branching is a fundamental feature of trees. Understanding how tree architecture is linked to tissue nutrient concentrations, metabolic rates, and life cycles is important for predicting ecosystem processes such as respiration, module turnover, and organic matter decomposition.2. Here, we examined branch order-nutrient relationships in above- and belowground tree branching systems by analysing nitrogen (N), phosphorus (P), and N : P ratio in leaves, the first three orders of twigs, and the first five orders of roots in 49 tree species, including 21 temperate angiosperm species, six temperate gymnosperm species, and 22 subtropical-tropical angiosperm species.3. Tissue [N] and [P] declined linearly with increasing twig and root orders across all species. The slope of the linear regression between root order and root [N] was the same between temperate and subtropical-tropical angiosperms, but steeper in angiosperms than gymnosperms. In contrast, root order-[P] relationship differed between biomes but not between phylogenetic groups, probably due to the significantly lower P availability in subtropical-tropical soils. Additionally, the magnitude of change in tissue [N] and [P] between successive shoot and root branch orders was not constant across branching levels. Among all fine root orders, first order root tips had [N], [P], and N : P ratio most similar to those of leaves.4. These results demonstrate that there is a general inverse order-nutrient relationship in above- and belowground modules, though specific patterns of this relationship differed between N and P, and between species groups. Moreover, among all root orders within the fine root guild, root tips are the best parallels of leaves in nutrient concentrations. The order-nutrient relationships presented here advances our understanding of functional module construction in trees, and provide a basis for modelling tissue chemistry-regulated processes such as respiration and decomposition in forest ecosystems.