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首页> 外文期刊>Tree Physiology >Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes
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Stomatal conductance, transpiration and sap flow of tropical montane rain forest trees in the southern Ecuadorian Andes

机译：厄瓜多尔南部安第斯山脉热带山地雨林树木的气孔导度，蒸腾作用和液流

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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.
机译：我们调查了1950-1975 m a.s.l.的热带山地热带雨林中树木与水的关系。在厄瓜多尔南部。在两次野外运动期间，对林分中大小和位置不同的16棵树（14种）进行了树液流量测量（格兰尼尔型）。测量了五棵冠层树和10种林下植物的气孔导度（g（s））和叶蒸腾（E（l））。气孔蒸腾作用的大气耦合很好（去耦系数Omega = 0.25-0.43），但是由于蒸气压不足的抵消作用，g（s）和E（l）对大气环境的响应似乎较弱（ VPD）和光合光子通量（PPF）on g（s）。相反，树液流量（F）更精确地遵循了这些大气参数。每日F主要取决于PPF的总和，而在短时间内，VPD超过1-1.2 kPa时会阻止蒸腾作用。这表明被调查树木的蒸腾量有上限，即使土壤水供应不受限制。冠层树的平均g（s）为165 mmol m（-2）s（-1），林下树种的平均g（s）为90 mmol m（-2）s（-1），但叶对叶以及树木之间的差异很大。考虑到整株植物的用水，在大小和冠状地位不同的树木中，F的日常变化比物种间的变化更为明显。每天的F随着茎直径和树高的增加而急剧增加，对于优势树冠树而言，介于80和120 kg·day（-1）之间，而对于森林内部的中间树和受压抑的树木而言，通常低于10 kg·day（-1）。

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