GAS EXCHANGE IN THE ROOTS OF MANGROVES
GAS EXCHANGE IN THE ROOTS OF MANGROVES
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红树林根部的气体交换
DOI：
10.1002/j.1537-2197.1955.tb11097.x
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发表时间：
1955
影响因子：
3
通讯作者：
S. I. Scholander
中科院分区：
文献类型：
--
作者：
P. F. Scholander;P. F. Scholander;L. V. Dam;L. V. Dam;S. I. Scholander;S. I. Scholander
沿着佛罗里达半岛的南部和西部海岸，出现了世界上最大的红树林沼泽地之一。芒果树，红红树林栖息在拱形的高跷根部，是优势物种，也是最具海洋性的物种。另一个重要的成分是白骨壤，黑红树林，仅限于潮汐带，在较隐蔽的内陆地区的潮间带泥滩上生长得最为茂盛。这两个物种对淡水都有相当大的耐受性（Davis，1943）。任何参观过红树林地区的人都熟悉的是空气根，它们大量地从白骨壤灌木或树木下面和周围的泥土中伸出。一棵树可以产生几千个这样的气根，通常20-30厘米。高，一厘米厚，柔软而海绵状，布满白色的小皮孔。在泥土中，它们连接到径向运行的主根，主根也是柔软和海绵状的，含有大量的空气（图1）。垂直气根通常被称为气根，因为人们认为它们可能具有使埋在泥土中的根系通气的功能。如果将Rhizophora的一根高跷根从泥中挖出来，就会发现它的末端是一束长的、海绵状的、手指粗的、充满空气的根（图2）。高跷的根有一个明显发展的气孔，人们可能会怀疑这些气孔是否可以作为泥根的通风口。如果是这样的话，人们可能会问通风是通过什么过程发生的，因为似乎几乎令人难以置信的是，泥土中庞大的根可以通过简单的扩散有效地通风，通过高跷根上的小漏斗。人们可能还想知道，这样一个从空气中获取氧气的系统如何避免被氮气堵塞。然而，在担心通风是如何发生之前，人们必须首先确定这种通风确实发生了，这就是本研究的目的。不同植物根的气体交换几位研究人员分析了生长在水中或泥中的植物根部的气体，这些植物缺氧。一般来说，这些根被发现是通气的;如何通常不清楚。Conway（1937）在对莎草Cladium mariscus R. Br.，发现空气空间从叶子到根部是连续的。天然气连接特别免费
ALONG THE southern and western coasts of the Florida peninsula occurs one of the greatest developments of mangrove swamp in the world. Rhizophora mangle L., the red mangrove, perching on its arched stilt roots, is the dominant species and the most marine. Another important component is Avicennia nitida Jacq., the black mangrove, which is restricted to the tidal zone and reaches its most luxuriant development on intertidal mud flats in more sheltered inland localities. Both species have a considerable tolerance for fresh water (Davis, 1943). Familiar to anyone who has visited the mangrove region are the air roots which protrude in great numbers from the mud under and around Avicennia bushes or trees. A single tree may produce several thousand of these air roots, usually 20-30 cm. high and a centimeter thick, soft and spongy, and studded with little whitish lenticels. In the mud they connect to radially-running main roots, which are also soft and spongy and contain large amounts of air (fig. 1). The vertical air-roots are often referred to as pneumatophores because it is believed that they may have the function of aerating the root system which lies buried in the mud. If one of the arching stilt roots of Rhizophora is dug out of the mud it is found to terminate in a bunch of long, spongy, finger-thick, and air-filled roots (fig. 2). The stilt root has a conspicuous development of lenticels, and one may wonder whether these might serve as ventilating ports for the mud roots. If they do, one might ask by what process the ventilation takes place, as it seems almost incredible that the voluminous roots down in the mud could be effectively ventilated by simple diffusion alone, through little lenticels high up on the stilt roots. One might also wonder how such a system, which gets its oxygen from the air, avoids getting jammed with nitrogen. However, before worrying over how the ventilation comes about one must first establish that such ventilation does take place, and this is the object of the present investigation. GAS EXCHANGE IN SUBMERGED ROOTS OF VARIOUS PLANTS.-Several investigators have analyzed the gases in roots of plants growing in water or mud which is poor in oxygen. In general these roots have been found to be aerated; how is usually not clear. Conway (1937), in a series of experiments on the sedge Cladium mariscus R. Br., found that air spaces were continuous from the leaves down into the roots. The gas connections were particularly free