Dynamics of water transport and storage in conifers studied with deuterium and heat tracing techniques

作者：Frederick C. Meinzer, J. Renée Brooks, Jean‐Christophe Domec, Barbara L. Gartner, J. M. Warren, David R. Woodruff, K. Bible, David C. Shaw · 发表于：Plant Cell & Environment · 年份：2005 · DOI：10.1111/j.1365-3040.2005.01404.x · 被引用次数：165 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Forest ecology and management

The volume and complexity of their vascular systems make the dynamics of long-distance water transport in large trees difficult to study. We used heat and deuterated water (D2)) as tracers to characterize whole-tree water transport and storage properties in individual trees belonging to the coniferous species Pseudotsuga menziesii (Mirb.) Franco and Tsuga heterophylla (Raf.) Sarg. The trees used in this study spanned a broad range of height (13.5-58 m) and diameter (0.14-1.43 m). Sap flow was monitored continuously with heat dissipation probes near the base of the trunk prior to, during and following injection of D2O. The transit time for D2O transport from the base of the trunk to the upper crown and the tracer residence time were determined by measuring hydrogen isotope ratios in water extracted from leaves sampled at regular intervals. Transit times for arrival of D2O in the upper crown ranged from 2.5 to 21 d and residence times ranged from 36 to 79 d. Estimates of maximum sap velocity derived from tracer transit times and path length ranged from 2.4 to 5.4 m d(-1). Tracer residence time and half-life increased as tree diameter increased, independent of species. Species-independent scaling of tracer velocity with sapwood-specific conductivity was also observed. When data from this study were combined with similar data from an earlier study of four tropical angiosperm trees, species-independent scaling of tracer velocity and residence time with sapwood hydraulic capacitanc...