Stem water storage and diurnal patterns of water use in tropical forest canopy trees
Stem water storage and diurnal patterns of water use in tropical forest canopy trees
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DOI：
10.1046/j.1365-3040.1998.00273.x
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发表时间：
1998-04-01
影响因子：
7.3
通讯作者：
Celis, A
中科院分区：
文献类型：
--
作者：
Goldstein, G;Andrade, JL;Celis, A
研究了巴拿马热带季节性森林5种树冠树木的茎贮水量和水分利用的日变化规律。用插入边材的恒定能量输入的热探头同时测定了每棵树顶部和底部的液流，通过比较基部和树冠液流的日变化规律，计算了树干的日贮水量。每天从储藏室中取出的水和随后补充的水量范围从直径为0.20 m的长柄天蛾个体的4 kg·d（-1）到直径为1.02 m的卓越腰果个体的54 kg·d（-1），分别占每日总失水量的9-15%。饮血榕、西氏紫花苜蓿和海甘蓝具有中等的昼夜贮水量。具有更大的存储容量的树木保持最大的蒸腾速率为一个实质性的更长的一天的一部分比树木具有较小的水存储容量。5种树木的日贮水量与基边材面积之间均呈线性关系，表明这种关系不依赖于树种，且具有一定的大小特异性。根据这种关系，基边材面积每增加0.1m2，日贮水量增加10 kg。内部储存是一个动态过程，与环境条件的波动密切相关。1100 h后，当内部储备大部分耗尽时，基部和树冠液流的变化更加同步。茎水储存可能部分补偿增加轴向水力阻力与树的大小，从而发挥重要作用，在调节叶片的水分状况暴露于大的日变化的蒸发需求，发生在上层冠层的季节性低地热带森林。
Stem water storage capacity and diurnal patterns of water use were studied in five canopy trees of a seasonal tropical forest in Panama, Sap flow was measured simultaneously at the top and at the base of each tree using constant energy input thermal probes inserted in the sapwood, The daily stem storage capacity was calculated by comparing the diurnal patterns of basal and crown sap flow. The amount of water withdrawn from storage and subsequently replaced daily ranged from 4 kg d(-1) in a 0.20-m-diameter individual of Cecropia longipes to 54 kg d(-1) in a 1.02-m-diameter individual of Anacardium excelsum, representing 9-15% of the total daily water loss, respectively. Ficus insipida, Luehea seemannii and Spondias mombin had intermediate diurnal water storage capacities. Trees with greater storage capacity maintained maximum rates of transpiration for a substantially longer fraction of the day than trees with smaller water storage capacity. All five trees conformed to a common linear relationship between diurnal storage capacity and basal sapwood area, suggesting that this relationship was species-independent and size-specific for trees at the study site, According to this relationship there was an increment of 10 kg of diurnal water storage capacity for every 0.1 m(2) increase in basal sapwood area, The diurnal withdrawal of water from, and refill of, internal stores was a dynamic process, tightly coupled to fluctuations in environmental conditions. The variations in basal and crown sap flow were more synchronized after 1100 h when internal reserves were mostly depleted. Stem water storage may partially compensate for increases in axial hydraulic resistance with tree size and thus play an important role in regulating the water status of leaves exposed to the large diurnal variations in evaporative demand that occur in the upper canopy of seasonal lowland tropical forests.