Weed communities and its dynamics in forest plantations of Sugi(Cryptomeria japonica) and Hinoki(Chamaecyparis obtusa)

本研究在日本博索半岛南部的东京大学森林中，对杉木（Cryptomeria japonica）和Hinoki（Chamaecyparis obtusa）人工林的杂草群落及其动态进行了研究。物种组成、结构等。主要调查了杉木人工林的杂草群落随时间的变化。同时，考察了人工林的生长状况和森林结构。暖温带杉木79年林分杂草群落以常绿阔叶树和常绿多年生草本植物为主。伐后1 ~ 3年幼龄林分植物种类明显多于伐前林分。经过清伐后的林分植被种类丰富。一年生植物直立木是1年龄林分的优势种。高草型芒草在2 ~ 7年间均为优势种。芒草的盖度（%）和重(g)呈逐年递增趋势，夏季刈割次数为1次。林冠闭合16 ~ 25年幼林的光照非常暗。距地面1m处的相对光照强度为0.03% ~ 3%。地上植物种数较少，每种数C × h总量较少。植物属藤本、丁香科、蕨类、兰科等少数种。主要存在于闭林林下。

The study was conducted in the forest of Tokyo university in the southern part of the Boso peninsula, to study the weed community and its dynamics in forest plantations of Sugi(Cryptomeria japonica) and Hinoki(Chamaecyparis obtusa). Species composition,structure,etc.of weed community changing with time were investigated mainly in sugi plantations. At the same time, growth status of planted trees,and forest structure were examined.Weed community in the 79-yr-old Sugi forest stand locating in the warm-temperate zone was composed mainly of evergreen broad-leaf trees and evergreen perennial herbs. The Number of plant species in the 1st-3rd-yr old young stands after clear-cutting has increased remarkably in comparison with stands before clear-cutting. The young stand vegetation after clear-cutting has become abundant in diversity of species. Erechitites hieracifolia which is the annual plant was the dominant species in the 1st-yr old stand after clear-cutting.Miscanthus sinensis of tall grass type was the most dominant species through out from 2 years to 7 years. The coverage(%) and weight(g) of Miscanthus sinensis which is the most major plants for mowing have increased annually by the mowing of 1 time in a year , in the summer seasons.The lightness in forest at 16-25 yr-old young stands of canopy closing was very dark. The relative light intensity at the 1m above the ground was from 0.03 up to 3 % . The Number of plant species on the ground was only a few, and total amount of C xH per species was only a little. Few species of plant belong to vine,Lilaceae, Pteridophyta,Orchidaceae,etc. have existed mainly in understory in closed forest.