Theoretical Study of Spatio-Temporal Dynamics of Synchronized Flowering and Reproduction of Trees in Forests

森林树木同步开花与繁殖的时空动态理论研究

基本信息

批准号：
12640616
负责人：
IWASA Yoh
金额：
$ 2.3万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Trees in mature forests often show intermittent reproduction. Intensive flowering and seed production occur only once in several years, often synchronized over a long distance. We study a coupled map model for the dynamics of energy reserve of individuals, and show that trees become synchronized in reproduction when their fruit production is limited by the availability of outcross pollen. Without pollen limitation, the trees show independent chaotic fluctuation. With global pollen coupling, trees show various degree of reproductive synchronization. Lyapunov exponents are calculated analytic ally for perfectly synchronized forests, demonstrating that synchronized reproduction of trees can occur only if trees flower at low (but positive) levels in a significant fraction of years, resulting in small fruit sets due to the shortage of outcross pollen. We then study a coupled map lattice with local pollen exchange. Dynamic spatial covariance shows that a strong synchronization over the whole forest can develop from rather short range pollen exchange. We then examined the synchronization caused by common environmental fluctuation either in the annual productivity or the reproductive threshold level. Without pollen coupling, positive correlation between individuals are difficult to emerge even under environmental fluctuation correlated between individuals. Positive correlation can be maintained at high level only in the presence of both pollen coupling and correlated environmental fluctuation. We also discuss the reproductive synchronization between different species who share common pollinators, which is applicable to the synchronization in the tropical rain forest in Southeast-Asia. The first paper was printed in JTB, the second in now (in press) in Ecology, and another was submitted to J Ecology.

成熟森林中的树木经常表现出间歇性繁殖。密集的开花和种子生产几年才发生一次，通常在很长的距离内同步进行。我们研究了个体能量储备动态的耦合图模型，并表明当树木的果实产量受到异交花粉的可用性限制时，树木的繁殖会同步。没有花粉限制，树木表现出独立的混沌波动。通过全局花粉耦合，树木表现出不同程度的生殖同步。李亚普诺夫指数是针对完全同步的森林进行分析计算的，表明只有当树木在相当长的时间内以低（但正）水平开花时，才会发生树木的同步繁殖，并由于异交花粉的缺乏而导致坐果量较小。然后我们研究了具有局部花粉交换的耦合图格。动态空间协方差表明，整个森林的强同步可以从相当短距离的花粉交换中发展出来。然后我们检查了由共同环境波动引起的年生产力或繁殖阈值水平的同步性。如果没有花粉耦合，即使个体之间存在相关的环境波动，个体之间也很难出现正相关。只有在花粉耦合和相关环境波动同时存在的情况下，正相关才能维持在较高水平。我们还讨论了具有共同授粉媒介的不同物种之间的生殖同步，这适用于东南亚热带雨林的同步。第一篇论文发表在 JTB 上，第二篇发表在 Ecology 上（正在出版），另一篇论文提交给 J Ecology。