Survival and ecophysiology of tree seedlings during El Niño drought in a tropical moist forest in Panama
Survival and ecophysiology of tree seedlings during El Niño drought in a tropical moist forest in Panama
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DOI：
10.1017/s0266467402002377
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发表时间：
2002-07
影响因子：
1.4
通讯作者：
Bettina M. J. Engelbrecht;S. Wright;D. Steven
中科院分区：
文献类型：
--
作者：
Bettina M. J. Engelbrecht;S. Wright;D. Steven
在热带森林，厄尔尼诺现象造成的严重干旱可能严重影响树苗的水分关系，从而增加其死亡率。本文报道了在巴拿马潮湿森林中三种常见的耐荫冠层树种（Trichilia tuberculata、Tetragastris panamensis和Quararibea asterolepis）的已知年龄幼苗的资料。在严重的厄尔尼诺干旱季节（1997-98年）的幼苗存活率与以前的长期存活数据进行了比较，并通过测量植物水势和气体交换特性来评估干旱胁迫的程度。与预测相反，旱季幼苗存活率并没有显着减少，在任何物种相比，预期在“正常”的年份。在Trichilia和Quararibea，黎明前的水势平均为-2 MPa，中午的水势约为-3 MPa。气孔导度非常低，Tetragastris平均为26 mmol m-2 s-1，Trichilia和Quararibea平均为11-13 mmol m-2 s-1。光合速率也很低，但始终为正，平均为0.8-1.1 μmol m-2 s-1。研究结果表明，一旦建立，在这个半落叶林常见树种的幼苗可能是耐受干旱事件。
In tropical forests, severe droughts caused by El Niño events may strongly influence the water relations of tree seedlings and thereby increase their mortality. Data on known-aged seedlings of three common shade-tolerant canopy tree species (Trichilia tuberculata, Tetragastris panamensis and Quararibea asterolepis) in a Panamanian moist forest are presented. Seedling survival during a severe El Niño dry season (1997-98) was compared with prior long-term survival data, and levels of drought stress were assessed by measuring plant water potentials and gas exchange characteristics. Contrary to prediction, dry-season seedling survival was not dramatically reduced in any species compared with that expected in ‘normal’ years. In Trichilia and Quararibea, pre-dawn water potentials averaged −2 MPa and midday water potentials about −3 MPa. Stomatal conductances were very low, averaging 26 mmol m-2 s-1 for Tetragastris and 11–13 mmol m-2 s-1 for Trichilia and Quararibea. Photosynthetic rates also were very low but consistently positive, averaging 0.8–1.1 μmol m-2 s-1. The findings suggest that, once established, seedlings of common tree species in this semi-deciduous forest may be tolerant of drought events.