Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes.
Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes.
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DOI：
10.1093/treephys/25.10.1283
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发表时间：
2005-10
期刊：
影响因子：
4
通讯作者：
Thomas Motzer;N. Munz;M. Küppers;Dieter Schmitt;D. Anhuf
中科院分区：
文献类型：
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作者：
Thomas Motzer;N. Munz;M. Küppers;Dieter Schmitt;D. Anhuf
我们调查了1950-1975年海拔较低的热带山地雨林的树木水分关系。在厄瓜多尔南部。在两个领域的运动，树干液流测量（Granier型）进行了16棵树（14种）不同的大小和位置的林分。气孔导度（g（s））和叶片蒸腾（E（l））进行了测定5冠层树木和10林下植物。气孔蒸腾的大气耦合较好（解耦系数Omega = 0.25-0.43），但由于水汽压亏缺（VPD）和光合光子通量（PPF）对g（s）的抵消作用，g（s）和E（l）对大气环境的响应较弱。相比之下，液流（F）更精确地遵循这些大气参数。日F主要取决于PPF总和，而在短时间尺度上，VPD阻碍蒸腾，当它超过1-1.2 kPa的值。这表明在调查树木的蒸腾上限，即使土壤水分供应是不受限制的。冠层树木的平均g（s）为165 mmol m（-2）s（-1），林下物种的平均g（s）约为90 mmol m（-2）s（-1），但叶与叶之间以及树与树之间的差异很大。考虑到整个植物的水分利用，在F的日常过程中的变化是更明显的树木不同的大小和冠状状态之间的物种。日F随树干直径和树高的增加而急剧增加，对于优势冠层树木，日F在80和120 kg/天之间，但对于森林内部的中间和抑制树木，日F通常远低于10 kg/天。
We investigated tree water relations in a lower tropical montane rain forest at 1950-1975 m a.s.l. in southern Ecuador. During two field campaigns, sap flow measurements (Granier-type) were carried out on 16 trees (14 species) differing in size and position within the forest stand. Stomatal conductance (g(s)) and leaf transpiration (E(l)) were measured on five canopy trees and 10 understory plants. Atmospheric coupling of stomatal transpiration was good (decoupling coefficient Omega = 0.25-0.43), but the response of g(s) and E(l) to the atmospheric environment appeared to be weak as a result of the offsetting effects of vapor pressure deficit (VPD) and photosynthetic photon flux (PPF) on g(s). In contrast, sap flow (F) followed these atmospheric parameters more precisely. Daily F depended chiefly on PPF sums, whereas on short time scales, VPD impeded transpiration when it exceeded a value of 1-1.2 kPa. This indicates an upper limit to transpiration in the investigated trees, even when soil water supply was not limiting. Mean g(s) was 165 mmol m(-2) s(-1) for the canopy trees and about 90 mmol m(-2) s(-1) for the understory species, but leaf-to-leaf as well as tree-to-tree variation was large. Considering whole-plant water use, variation in the daily course of F was more pronounced among trees differing in size and crown status than among species. Daily F increased sharply with stem diameter and tree height, and ranged between 80 and 120 kg day(-1) for dominant canopy trees, but was typically well below 10 kg day(-1) for intermediate and suppressed trees of the forest interior.