Ecosystem analysis of montane natural forest within a large scale research plot in Chichibu Mountains

通过三年(1994-‘96)的种子诱捕器对山毛榉(50m×50m)种子生产的研究。日本水曲柳在1995年有较好的种子年，金针茅在1996年有正常的种子年。在这三年(Kaji)，两种山毛榉的种子生产不是在同一年发生的。以大比例尺样地(5.0625ha)林木(胸径和胸径5 cm)的完整计数资料为基础，分析了林分地貌特征与地形因子的相关性以及树种的空间分布与地形因子的关系。几组树种的分布与地貌因子(Ohkubo&Kaji)密切相关。研究了日本小蜂和圆叶小实蝇节肢动物种类和种群密度的季节和空间变化。山毛榉上节肢动物的垂直分布在不同类群之间存在较大差异。两种山毛榉的食草性昆虫密度不同。通过对大型样地及周边鸟类的调查，共记录到鸟类70种，其中繁殖鸟37种。研究区种鸟的Shannon多样性指数较高(5.04)，但与研究区植被结构的多样性指数(Ishida)相比并不算高。通过对山毛榉不同高度(23m高)的温度和日照时间的观测，推算出山毛榉落叶时间分别为1995年11月7日~9日和1996年11月2日~6日。据估计，1996年5月17日左右发生了冲刷。林冠以上气温日较差最大，近地表气温日较差逐渐变小。从落叶期和落叶期的日平均温度比较来看，落叶期对温和的森林气候(Kabaya&Shibano)更为有效。

From a research on seed production of beech trees in a plot (50m*50m) by seed traps for three years (1994-'96). Fagus japonica had a good seed year in 1995 and F.crenata had a normal seed year in 1996, respectively. The seed production of two beech species did not occur in a same year in these three years (Kaji). Based on the data of complete enumeration of trees (DBH>5cm) in a large scale research plot (5.0625ha), correlation between physiognomical characteristics of stands and topographic factors and spatial distribution of tree species in relation to the topographic factors were analyzed. The distribution of several groups of tree species intimately correlated with topoghraphic factor (Ohkubo & Kaji). Seasonal and spatial change of species and population density of arthropods on F.japonica and F.crenata trees were investigated. Vertical distribution of arthropods on beech trees was largely different among taxa. The density of herbivorous insects was different between two kinds of beech trees. From bird research within a large scale research plot and its surroundings, 70 bird species were recorded, among which 37 species breeded. Shannon's diversity index of breeding birds in a research area showed a high value (5.04), However, this value was not so high in comparison with the high diversity of vegetation structure in the research area (Ishida). From observation of temperature and insolation in several different height on a tower (23m high), dates of defoliation in beech stand were estimated at Nov.7th-9th.in 1995 and at Nov.2nd.-6th.in 1996, respectively. It is also estimated that flushing occurred at ca.May 17th.in 1996. Diurnal range of air temperature was the largest above forest canopy, and it was getting smaller near ground surface. From comparison of mean diurnal temperature between defoliation and foliation periods, the latter period is more effective to moderate forest climate (Kabaya & Shibano).