Chemical Ecology of an Invader (Podocarpus Nagi)

山小山包西坡为以竹柏为主的竹柏林。米卡萨位于日本中部奈良县的首府奈良市的东北部，海拔294米。在1400多年的漫长历史中，它一直以春日神社为背景受到保护。大约一千年前，为了表达对神道教神灵的敬意，在山脚下人工种植了一些罗汉果树，这些树已经侵入了当地的植被，日本阔叶万年青林。这种入侵者是侵略性的其他植物，由于其化感化学物质，Nagi-内酯与六个光学异构体。本研究是关于侵略性入侵者长木松（P. nagi）采取的一种生命策略的化学生态学。化学物质明显抑制了原生树木的发芽和初期生长，并从食草动物中释放了长木松，其主要成分是生活在森林中的1000只鹿，被保护为神社神道教的冬青动物。凋落物中有大量的化学物质从林冠层流到林下，降雨中有大量的化学物质从林冠层流到林下。因此，森林生态系统中化学物质的循环与碳循环和养分循环密切相关，表明入侵者具有自毒作用，森林土壤受到化学物质的污染，导致森林结构和森林组成不良。入侵者是雌雄同株的物种，性比为1：1。入侵种幼苗的分布格局依赖于雄株。该入侵种的物候现象表明其起源于热带，其结实期每四年一次，与ENSO有很高的相关性。

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.