Community photosynthesis of aquatic macrophytes
Community photosynthesis of aquatic macrophytes
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DOI：
10.4319/lo.2006.51.6.2722
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发表时间：
2006-11-01
影响因子：
4.5
通讯作者：
Middelboe, Anne-Lise
中科院分区：
文献类型：
--
作者：
Binzer, Thomas;Sand-Jensen, Kaj;Middelboe, Anne-Lise
我们比较了190个光合作用辐照度（P-E）实验与单种和多种群落的大型藻类和维管植物从淡水和海洋栖息地。在所有群落中均发现了典型的双曲线P-E关系，在最高辐照度约2，000 μ mol·m（-2）·s（-1）时，没有光合作用光饱和或光抑制的迹象。大型植物群落表现出更高的最大生产总值（GP（max））呼吸，和光补偿点比单独的植物元素，因为在社区的多层结构和广泛的自我遮光，而在低辐照度（α）的光利用效率是相同的。虽然GP（max）和α在190个群落中变化很大，但它们的上限随着群落吸收率的线性和可预测的增加而增加，在100%吸收时达到26.3 μ mol m（-2）s（-1）O-2和0.090 mol mol（-1）光子。a的上限接近O-2的实际极限0.10 mol mol（-1）光子。然而，GP（max）的上限明显低于理论上可达到的180 mol m（-2）s（-1）O-2，反映了次优的三维结构和光分布。间接测量支持这一解释，因为GP（max）从非常不均匀的社区增加到更均匀的光分布。植物群落的光合特性受植物密度、吸收和光分布的强烈影响，不能用植物元素的光合行为来解释。因此，许多例子中的碳和养分限制在实验中与单独的植物元素可能无法承受在相关的生态规模的社区，其中光几乎总是限制光合生产。
We compared 190 photosynthesis-irradiance (P-E) experiments with single- and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P-E relation in all communities and no sign of photosaturation or photoinhibition of photosynthesis at the highest irradiances of about 2,000 mu mol m(-2) s(-1). Macrophyte communities displayed much higher maximum gross production (GP(max)) respiration, and light compensation point than separate phytoelements because of the multilayered structure and extensive self-shading in the communities, whereas light use efficiency at low irradiance (alpha) was the same. Although GP(max) and alpha varied extensively among the 190 communities, their upper limits increased linearly and predictably with community absorption reaching 26.3 mu mol m(-2) s(-1) O-2 and 0.090 mol mol(-1) photon at 100% absorption. The upper limit of a is close to a realistic limit of O-2 of 0.10 mol mol(-1) photon. The upper limit of GP(max), however, is markedly below the theoretically attainable 180 mol m(-2) s(-1) O-2, reflecting a suboptimal three-dimensional structure and light distribution. Indirect measures supported this explanation as GP(max) increased fourfold from communities with a very uneven to a more even light distribution. Photosynthetic characteristics of communities are strongly influenced by plant density, absorption, and distribution of light and cannot be interpreted from the photosynthetic behavior of phytoelements. Thus, many examples of carbon and nutrient limitation in experiments with separate phytoelements may not withstand at the relevant ecological scale of communities where light almost always constrains photosynthetic production.