The hydraulic system of trees: theoretical framework and numerical simulation
The hydraulic system of trees: theoretical framework and numerical simulation
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树木液压系统：理论框架和数值模拟
DOI：
10.1006/jtbi.1999.1028
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发表时间：
1999
影响因子：
2
通讯作者：
Kurth
中科院分区：
文献类型：
--
作者：
Fruh;Kurth
经验研究提出了树木有机体的生理整合问题，这在生态系统规模上也很重要。最近，出现了空间分布模型，它通过反映生理过程与树木和树木林分结构之间的密切联系来解决这个问题。在水流作用下，树体可看作水力系统，分枝树形结构可看作水力网络。以前的模型的液压系统要么没有考虑到网络结构，或者他们有缺点的基本生理假设的离散计算方法的翻译。我们已经开发了一个理论框架，它的形式是树木水流的数值模拟模型。离散初边值问题（IBVP）结合了水力网络中的达西流、水存储和传导损失现象。软件HYDRONIC计算IBVP的解。理论推导和模型试验证实了计算方法对生理假设的一致性翻译。模拟研究使我们能够制定以下几点的假设：（1）云杉和崖柏之间的水力分割的差异，（2）的水力系统的快速蒸腾变化和干旱胁迫的情况下的反应，以及（3）这些反应如何依赖于建筑数量的树木。模拟研究表明，我们的可能性，推导出理论上有充分根据的假设的液压系统的功能和它的关系，系统结构。该数值模拟模型是一种能够将树木构型作为自变量处理的结构-功能研究工具。该模型支持树级数据的集成，它可以用于根据系统理论的概念量化液压系统的动态的计算机实验。版权所有1999年学术出版社。
Empirical studies pose the problem of the physiological integration of the tree organism, which is also important on the scale of ecosystems. Recently, spatially distributed models emerged, which approach this problem by reflecting the close linkage between physiological processes and the structures of trees and tree stands. In the case of water flow, the tree organism can be regarded as hydraulic system and the branched tree architecture as hydraulic network. Previous models of the hydraulic system either did not take into account the network structure, or they had shortcomings regarding the translation of the underlying physiological assumptions by the discrete computation method. We have developed a theoretical framework which takes the form of a numerical simulation model of tree water flow. A discrete initial boundary value problem (IBVP) combines the phenomena of Darcy flow, water storage and conductivity losses in the hydraulic network. The software HYDRA computes the solution of the IBVP. The theoretical derivation and model tests corroborate the consistent translation of the physiological assumptions by the computational method. Simulation studies enabled us to formulate hypotheses on the following points: (1) differences in the hydraulic segmentation between Picea abies and Thuja occidentalis, (2) responses of the hydraulic system to rapid transpiration changes and to a scenario of drought stress, and (3) how these responses depend on architectural quantities of the trees. The simulation studies demonstrated our possibilities of deriving theoretically well-founded hypotheses about the functioning of the hydraulic system and its relation to system structure. The numerical simulation model is designed as a tool for structure-function studies, which is able to treat tree architecture as independent variable. The model supports the integration of data on tree level, and it can be used for computer experiments which quantify the dynamics of the hydraulic system according to the concepts of system theory. Copyright 1999 Academic Press.