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首页> 外文期刊>Berichte des Meteorologischen Institutes der Universitat Freiburg >Variability of light quality and quantity in a mixed forest stand
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Variability of light quality and quantity in a mixed forest stand

机译：混交林分中光质和光量的变化

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摘要

Light quality and quantity affects different characteristics in growth and competition within forest stands. These parameters deliver crucial energetic information about the light environment to the plants. Especially the spectral waveband between 400 and 700 nm (PAR) is mainly responsible for photosynthesis and thus for plant growth. Spectral ratios e.g. red/far red (R/FR)and blue/red (B/R) give important information about the light quality within stands. The R/FR is important for the detection of competition, structure and architecture, and internode expansion.Blue light strongly influences development and growth of plants; e.g. an increase of B/R may lead to higher photosynthetic rates per unit leaf area. In addition to spectral properties, a higher fraction of diffuse radiation on overcast days can be used more effectively by plant organs.In this study, the spectral composition and variability of solar radiation were analyzed for different sky conditions (CS: clear, OVC: overcast) and solar angles in six different vertical layers of a mixed European beech and Norway spruce stand in Bavaria.Solar elevation and sky conditions have great impact on the absorption of the entire PAR band.While the frequency of sunflecks decreases strongly from the sun to the shade crown, it does not show high variability among the species, sky conditions, or phenological stages when compared at the same canopy level.The B/R ratio shows significantly higher values for spruce in comparison to beech at CS conditions.For both investigated species a strong increase of B/R in the sun crown and a strong decrease in the shade crown can be observed. Low solar angles result in higher B/R values. Differences in R/FR between beech and spruce are the result of the architecture of the respective species.R/FR increases under OVC conditions, while it decreases under CS conditions and increasing canopy cover.
机译：光的质量和数量会影响林分生长和竞争的不同特征。这些参数将有关光照环境的至关重要的能量信息传递给植物。特别是在400至700 nm（PAR）之间的光谱波段主要负责光合作用，从而促进植物生长。光谱比红色/深红色（R / FR）和蓝色/红色（B / R）提供有关展位内光质量的重要信息。 R / FR对于检测竞争，结构和架构以及节点间扩展很重要。蓝光强烈影响植物的生长和发育;例如B / R的增加可能导致每单位叶片面积更高的光合速率。除光谱特性外，植物器官还可以更有效地利用阴天的较高比例的漫射辐射。在这项研究中，分析了不同天空条件下太阳辐射的光谱成分和变异性（CS：晴朗，OVC：阴）和欧洲云杉和挪威云杉混合在巴伐利亚的六个不同垂直层中的太阳角，太阳高程和天空条件对整个PAR波段的吸收有很大影响，而太阳斑的频率从太阳到在相同的冠层水平上进行比较时，树冠之间没有变化，在物种，天空条件或物候期之间也没有很大的变化。在CS条件下，B / R比与云杉相比，云杉的值明显更高。可以观察到太阳冠中B / R的强烈增加和阴影冠中的强烈降低。较低的太阳角会导致较高的B / R值。山毛榉和云杉之间的R / FR差异是各自物种的结构造成的.R / FR在OVC条件下会增加，而在CS条件下会减少并且冠层覆盖增加。

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