Analysis of canopy structure of multi-species plant communities

植物群落由植物高度不同的一系列物种组成。占据冠层上层的高大优势种接收一大部分光子通量密度，而占据较低层的小从属物种接收一小部分可用光子。然而，高大树种在支持组织上投入了相对更多的生物量，以将它们的叶子放在树冠上的较高位置。因此，高大优势种和小优势种的单位地上生物量吸收的光子数是相似的。通过两年的研究，我们发现：(1)川崎芒属林分中，在生长季节初期，附属树种狼尾草等地上单位生物量的光吸收较高，而优势芒果在生长季节后期较高。这使得从属物种能够与优势芒属共存。(2)在温室内建立了水稻(C3)和谷子(C4)的混交林，并进行了竞争…分析了这些物种之间的更多差异。谷子萌发晚于水稻，但其生长速度大于水稻植株。水稻使谷子的生长减少了5%，而谷子使水稻的生长速度减少了30%。(3)建立了密林中个体光合作用的估算模型，并分析了影响个体大小等级形成的因素。高大优势株比受抑制株具有更大的单位地上生物量光吸收和单位吸收光量子通量密度的光合作用速率，加剧了林分的大小层次结构。(4)建立模型，分析不同氮素在光合蛋白之间的分配对光合作用能力的影响。根据光照条件的不同，最优的分配可以使光合作用效率提高20%。(5)比较了阳生植物和阴生植物的蛋白质分配。两个物种的蛋白质分配都接近理论上的最优。较少

A plant communty consists of a range of species different in plant height. Tall dominant species occupying upper layrs in the canopy receive a large fraction of photon flux density, while small subordinate species occupying lower layrs receive small fractions of available photons. Tall species, however, invest relatively more biomass to supporting tissues to position their leaves high in the canopy. Thus photon absorption per unit aboveground biomass is similar between tall dominant and small subordinate species. Through the two-year study, we found : (1) In the Miscanthus sinensis stand at Kawatabi, photon absorption per unit aboveground biomass of subordinate species such as Lysimachia japonica was high early in the growing season, while that of dominant Miscanthus sinensis was high late in the growing season. This enables subordinate species to coexist with dominant Miscanthus sinensis. (2) Mixed stands of rice (C3) and millet (C4) were established in a greenhouse and competition be … More tween these species was analyzed. Although millet germinating later than rice, its growth rate was larger than rice plants. Rice reduced the growth of millet by 5%, while millet reduced the growth rate of rice up to 30%. (3) We developed a model to estimate photosynthesis of individuals in a dense stand and analyzed factors involved in the development of size hierarchy. Tall dominant plants had larger photon absorption per unit aboveground biomass and larger photosynthetic rates per unit absorbed photon flux density than suppressed plants, intensiflying the size hierarchy of the stand. (4) A model was made to analyze the effect on photosynthetic capacity of different nitrogen partitioning among photosynthetic proteins. The optimal partitioning, depending on light conditions, lead to up to 20% increase in photosynthetic efficiency. (5) We compared protein partitioning between sun (Chenopodium album) and shade (Alocasia macrorrhiza) plants. Both species had protein partitioning close to the theoretical optimum. Less