Effects of artificial disturbance of river on the biodiversity of the river forest

为了探讨河滨林生物多样性的机制，我们对日本温带地区几种保存完好的河滨林中几种优势树种的繁殖策略和交配系统进行了调查。在雌雄异株树种柳树中，我们揭示了有性生殖和无性生殖的相对重要性与林分年龄的关系。在柳树中，雌性在繁殖上投入了更多的资源，但它们有几种优越的生理、形态和物候机制来补偿繁殖成本。我们还揭示了河滨植物Jugalns ailanthifolia是一种异性双性生殖物种，具有两种类型的开花酚类。这两种类型对男性和女性各自的功能都进行了平等的投资。雄性和雌性的繁殖成功率也几乎相同。我们用稳定同位素揭示了从山上河边森林中的落叶到海上捕鱼的食物链。这项研究为保护天然河岸林对维护生物多样性的重要性提供了证据。

To evaluate the mechanisms of bio-diversity of riverside forests, we investigated the reproductive strategies and mating systems of several dominant tree species in several well-preserved riverside forests in temperate region of Japan. In the dioecious tree species, Salix sp., we revealed the relative importance of sexual and asexal reproduction in relation to stand ages. In Salix sp., female invest much more resource to reproduction, but they have several superior physiological, morphological, and phenological mechanisms to compensate the reproductive cost. We also revealed that a riverside species, Jugalns ailanthifolia, is a heterodichogamous species, which have two type of flowering phenolgies. Both types invest equally to each of male and female function. Male reproductive success was also almost identical to that of females.We revealed the food chain from litter fall in mountaneous river side forest to fish in sea by using stable isotope. This study provide the evidences of importance of the preservation of natural riverside forests to maintain the bio-diversity.