Competition and coexistence in plant community in relation to strategy of resource us

植物群落由大小不同的个体和物种组成。我们研究了这些个体和物种如何获取和利用群落中的有限资源，以阐明物种和个体之间的竞争和共存机制。川崎芒草草甸林冠上层以芒属植物为主，林下植物以芒属植物为主，多个较小的从属植物如金缕梅和金莲花共存。虽然林下优势种对PPFD的吸收远小于优势种，但相对于地上生物量，它们的叶面积较大，因此单位地上生物量吸收的PPFD与芒属接近。这表明，在植物群落中物种共存的必要条件是每单位地上生物量投资具有相似的采光效率。我们研究了La…海岸的加拿大苍耳天然林更多的KE卡马胡沙作为一种竞赛制度。高大个体位于上层，吸收了大量的有效PFDs，上层和下层个体叶面积比差异有限，上层个体的光获取效率仍然大于下层个体。这与上面给出的共存制度形成了强烈的对比。不同生长阶段林分的比较表明，株高和光气候控制着个体叶面积的发育。我们进一步研究了在两种氮素利用率下建立的冠层中叶片的光合作用特性。与普通光照气候相比，低层植物叶片中的氮素浓度趋于较高。然而，叶片光合作用中的氮素利用完全取决于叶片的光气候。我们开发了最优分配模型，以研究在传粉者可用或资源可用不可预测的环境中，更好地对冲胚珠生产作为一种进化策略。我们发现，授粉者或资源可用性的巨大变异性并不总是选择植物产生的胚珠数量的增加。相反，在传粉者或资源可获得性更不稳定的生境中，植物会减少其I胚珠数量。为了解释两性植物中偏向雌性的性别分配，我们建立了一个包含花/果实生长的源-库关系的博弈论模型。在这个模型中，花/果的生长速度要么受到库强度(潜在的相对生长率和绝对大小的乘积)的限制，要么受到植物的源强度(可用资源的瞬时数量)的限制。我们发现，如果果实的生长受库容量限制，至少在其生长的早期阶段，女性偏向的性别分配在进化上是稳定的。较少

A plant community consists of individuals and species which are different in size from each other. We studied how those individuals and species acquire and use limiting resources in the community to elucidate the mechanism of competition and coexistence among species and individuals. In the Miscanthus sinensis grassland meadow at Kawatabi, Miscanthus dominated upper layrs of the canopy, while many smaller subordinate species such as Potentila and Lysimachia coexisted in the understory. Although those subordinate understory species absorbed much smaller amounts of PPFD than dominant Miscanthus, they have larger leaf area relative to aboveground biomass and consequently the PPFD absorbed per unit aboveground biomass was closer to that of Miscanthus. This suggests that a similar efficiency of light acquisition per unit investment of aboveground biomass is a necessary condition for species coexistence in a plant community. We studied a natural stand of Xanthium canadense at the shore of La … More ke Kamahusa as a competition system. Tall individuals were in the upper layr and absorbed large amounts of available PPFD.Difference in the leaf area ratio between individuals in upper and lower layrs was limited and consequently the efficiency of light acquisition of the individuals in the upper layr was still larger than that in the lower layr individuals. This made a strong contrast against the coexistence system given above. From a comparison between stands different in the growth stage, it was shown that plant height and light climate controlled leaf area development of individuals. We further studied photosynthetic characteristics of leaves in a canopy established experimentally at two nitrogen availabilities. Leaf nitrogen concentration tended to be higher in leaves of plants in lower layrs when compared at a common light climate. However, nitrogen use in leaf photosynthesis depended solely on the light climate of the leaf.We developed optimal-allocation models to investigate bet-hedging on ovule production as an evolutionary strategy in environments where either pollinator availability or resource availability is unpredictable. We showed that large variability in pollinator or resource availability does not always select for an increase in the number of ovules produced by the plant. Rather, the plant decreases its I ovule number in habitats where pollinator or resource availability is more variable. To explain female-biased sexual allocation in cosexual plants, we developed a game theoretic model incorporating a source-sink relationship of flower/fruit growth. In this model, flower/fruit growth rate is either limited by its sink strength (the product of its potential relative growth rate and absolute size) or by the source strength (instantaneous amount of resources available) of the plant. We showed that female-biased sexual allocation is evolutionarily stable if fruit growth is sink-limited at least in the early stage of its growth. Less