Importance of structure and density of macroalgae communities (Fucus serratus) for photosynthetic production and light utilisation
Importance of structure and density of macroalgae communities (Fucus serratus) for photosynthetic production and light utilisation
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DOI：
10.3354/meps235053
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发表时间：
2002-01-01
影响因子：
2.5
通讯作者：
Sand-Jensen, K
中科院分区：
文献类型：
--
作者：
Binzer, T;Sand-Jensen, K
确定植物群落的光合产量对于评估生态系统中的植物生长速率和碳通量至关重要，但它不能轻易地从单个叶子或菌体的光合反应中得出，而这一直是几乎所有先前水生研究的焦点。 密度和空间结构暴露于不同的光子通量密度和溶解的二氧化碳浓度下，与光子通量密度相关的光合生产在整个群落和单个叶状体部分之间存在很大差异。群落没有发生光饱和，所有光合变量，如光补偿点、弱光下的光利用效率和高光下的最大产量都取决于群落密度。因此，虽然确定单个藻类菌体的产量对于评估物种和林分之间的驯化和适应差异很有用，但对于评估整个植物和群落的生产率却没有用处。随着群落密度的增加，F. serratus 的最大总产量遵循双曲线曲线，在叶面积指数 (LAI) 为 8 至 10 时达到最大值 30 mumol O-2 (m(2) 地面面积)(-1) s(-1)。在 LAI 为 6 至 8 时，达到光照下的最大净群落产量，而在 LAI 为 5 至 6 时，达到自然昼夜循环的最大值。最大总产量约为3倍 F. serratus 群落中的含量低于森林、草原和农作物中的陆地群落。将 F. serratus 群落控制为更加垂直的结构，增加了群落的光穿透和总产量，这意味着冠层结构对群落生产具有深远的影响，并且非最佳的光分布可能是水生植物群落最大总生产率低于陆生植物群落的主要原因。
Determination of photosynthetic production in plant communities is essential for evaluating plant growth rates and carbon fluxes in ecosystems, but it cannot easily be derived from the photosynthetic response of individual leaves or thalli, which has been the focus of virtually all previous aquatic studies, To evaluate the regulation of aquatic community production, we measured the photosynthetic production of thallus parts and entire communities of Fucus serratus (L.) of different density and spatial structure exposed to varying photon flux density and dissolved CO2 concentration, Photosynthetic production in relation to photon flux density differed considerably between entire communities and individual thallus parts. No light saturation occurred in the communities, and all photosynthetic variables such as light compensation point, efficiency of light utilisation at low light and maximum production at high light depended on community density. Therefore, while the determination of the production of individual algal thalli is useful for evaluating differences in acclimatisation and adaptation between species and stands, it is not useful for evaluating production rates for entire plants and communities. Maximum gross production of F. serratus followed a hyperbolic curve at increasing community density, reaching a maximum of 30 mumol O-2 (m(2) ground area)(-1) s(-1) at a leaf area index (LAI) of 8 to 10. Maximum net community production in the light was attained at an LAI of 6 to 8, while the maximum in a natural day-night cycle is attained at an LAI of 5 to 6. Maximum gross production was about 3-fold lower in F. serratus communities than in terrestrial communities in forests, grasslands and crops. Manipulating F. serratus communities to a more vertical structure increased light penetration and gross production in the communities, implying that canopy structure had a profound influence on community production and that a non-optimal distribution of light is likely to be the main reason for the lower maximum gross production rates in aquatic than terrestrial plant communities.