Maberly Stephen C, Madsen Tom V
Centre for Ecology and Hydrology Windermere, The Ferry House, Far Sawrey, Ambleside LA22 0LP UK.Corresponding author; email:
Department of Plant Ecology, University of Aarhus, 68 Nordlandsvej, DK8240 Risskov, Denmark.
Funct Plant Biol. 2002 Apr;29(3):393-405. doi: 10.1071/PP01187.
Aquatic angiosperms are derived from terrestrial ancestors and appear to have re-invaded water on many occasions. While removing problems of water supply and reducing the need for supporting tissue, freshwaters have a potentially low and fluctuating supply of CO2 for photosynthesis, as well as generally low light. This paper reviews the structural, morphological, physiological, and biochemical features of freshwater macrophytes in the context of maximising net carbon uptake underwater, and discusses how inorganic carbon may influence macrophyte ecology. Submerged leaves tend to have a low photosynthetic capacity on an area basis, matching the low rates of supply of CO2 and light. Morphological and structural strategies to overcome potential carbon limitation include possession of aerial or floating leaves, and lacunal connexions to high concentrations of sedimentary CO2 via the roots. Physiological and biochemical strategies include crassulacean acid metabolism, C4-like metabolism in Hydrilla and Egeria, and the ability to use HCO3 The activity of all these can be regulated by environmental conditions to maximize growth rate. Use of HCO3 is the most widespread carbon acquisition strategy, present in about half of the tested submerged angiosperms. It is more common in lakes of high alkalinity and in the elodeid growth form.
水生被子植物起源于陆生祖先，似乎在许多情况下重新侵入了水域。虽然解决了供水问题并减少了对支撑组织的需求，但淡水的二氧化碳供应可能较低且波动，用于光合作用，而且光照通常也较弱。本文在最大化水下净碳吸收的背景下，综述了淡水大型植物的结构、形态、生理和生化特征，并讨论了无机碳如何影响大型植物生态学。从单位面积来看，沉水叶的光合能力往往较低，这与二氧化碳和光照的低供应率相匹配。克服潜在碳限制的形态和结构策略包括拥有气生叶或浮叶，以及通过根部与高浓度沉积二氧化碳的腔隙连接。生理和生化策略包括景天酸代谢、黑藻和伊乐藻中的C4类代谢，以及利用碳酸氢根的能力。所有这些活动都可以受环境条件调节，以最大化生长速率。利用碳酸氢根是最广泛的碳获取策略，约一半的受试沉水被子植物都有这种策略。它在高碱度湖泊和伊乐藻生长形式中更为常见。
