Chemical Ecology of an Invader (Podocarpus Nagi)

入侵者的化学生态学（罗汉松）

• 批准号: 01480007
• 负责人: YAMAKURA Takuo
• 金额: $ 4.29万
• 依托单位: Osaka City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-01480007/
• 关键词: Chemical Ecology; Nagi-Lacton; Allelopathy; Chemical Defense; Ecological Invasion; アレロパシ-

A podocarp forest with Podocarpus nagi dominant covers the west slope of a small hill, Mt. Mikasa with a peak of 294 m in altitude, situated on the north-eastern part of Nara City, the capital of Nara Prefecture, Central Japan. It has been protected for a background of the Kasuga Shinto Shrine through long historical time over 1400 years. Since some podocarp trees was artificially planted on a foot of the hill about a thousand years ago to express man's respect to the Shinto Gods, the trees has been invading into the native vegetation, Japanese broadleaved evergreen forest. This invader is aggressive to other plants owing to its allelopatic chemicals, Nagi-lactones with six optical isomers. This study is concerned with chemical ecology of a life strategy adopted by an aggressive invader P. nagi.The chemicals clearly inhibited the germination and initial growth of native trees and released P. nagi from grazers, whose major component was one thousand deers living in the forest and has been protected as a holly animal of the Shinto Gods at the Shrine. There was substantia '1 flow of chemicals from forest canopy to forest floor in litterfall and the others : throughfall and stemflow in rain. Therefore the cycle of the chemicals in the forest ecosystem was highly correlated with carbon and nutrient cyclings, suggesting the auto-intoxication of the invader.Forest soil was polluted by the chemicals and resulted in the poor forest architecture and frolal composition. The invader is a monoecious species with a sex ratio of 1 : 1. The distribution pattern of seedlings of the invader depend on the male trees. The phenological phenomena of the invader suggested its tropical origin and its mast fruiting was observed every four years implying the high correlation with the ENSO.

位于日本中部奈良县首府奈良市东北部的三笠山海拔294m，西坡上覆盖着以罗汉松为主的罗汉松林。以春日神社为背景，经过1400多年的悠久历史而受到保护。自从大约一千年前在山脚下人工种植了一些罗汉松树以表达人类对神道教神的敬意以来，这些树已经侵入了本土植被——日本常绿阔叶林。这种入侵者因其异体化学物质（具有六种光学异构体的 Nagi-内酯）而对其他植物具有攻击性。这项研究关注的是侵略性入侵者 P. nagi 所采用的生命策略的化学生态学。这些化学物质明显抑制了本地树木的发芽和初始生长，并将 P. nagi 从食草动物中释放出来，其主要成分是生活在森林中的 1000 只鹿，并在神社作为神道教神的冬青动物受到保护。在凋落物和其他物质中，有大量的化学物质从森林冠层流向森林地面：雨水中的径流和茎流。因此，森林生态系统中化学物质的循环与碳和养分循环高度相关，这表明入侵者具有自毒作用。森林土壤受到化学物质的污染，导致森林结构和花组成较差。入侵者为雌雄同株，性别比为1：1。入侵者幼苗的分布格局取决于雄树。入侵者的物候现象表明其起源于热带，每四年观察一次其肥大结果，这意味着与 ENSO 高度相关。

项目成果

川口 英之・山倉 拓夫: "Litter Fall Patterns in a <Podocarpus nagi>___ー Forest" Abstracts of V International Congress of Ecology. 388 (1990)

Hideyuki Kawaguchi 和 Takuo Yamakura：“<Podocarpus nagi>___ 森林中的垃圾掉落模式”第五届国际生态学大会摘要（1990 年）。