WBC-VIII-Vol.4 – Resources – Forestry, Plantations and ... - BambuSC

Dynamics of P. bambuoides Forest during the Recent 16 years
Trees
Table 3 shows the change of main tree species number during recent 16 years in the research site. In 1992, 262
trees of 21 species (deciduous: 13, evergreen: 8) existed in 40m*40m quadrate, and 25 trees (9.5%) formed
forest canopy with bamboo. Main tree species forming forest canopy was Aphananthe aspera, Celtis sinensis
and Zelkova serrata etc.. The rest 237 trees, mainly evergreen broad-leaved species, were not the component of
forest canopy, and existed as the component of forest floor vegetation.
In 1999, tree species number decreased to 177 of 12 species (deciduous: 6, evergreen: 6). However, the number
of trees forming forest canopy was invariable (25 individuals) and the rate of them increased to 14%. The
individuals of Aphananthe aspera, Zelkova serrata and Ligustrum japonicum did not decrease. The former two
species are forming forest canopy, and the latter is the component of shrub layer. Quercus glauca showed
comparatively dynamic change. In many cases, although its trunks which were alive in 1992 died during the
following years, it produced coppice shoots again. This kind of ability to produce new shoots is superior on this
species. But other species poor in this ability tend to decrease their individuals. All Cryptomeria japonica,
planted species, died out during the research. The seedlings and saplings of tree species composing the forest
canopy were seldom shown in the forest floor layer except a little amount of Zelkova serrata saplings.
In 2003, although the number of trees decreased a little to 165, tree species components and forest canopy
forming trees did not change. Decrease of the number caused by the slow-down of decrease of Camellia
japonica, Neolitsea sericea and Cinnamomum sieboldii after 1999. On the other hand, the decrease of Celtis
sinensis was continuing. It is considered that the change of tree species tends to become stable.
Phyllostachys bambusoides
The density of new culms of P. bambusoides changes every year. In the research site, the number per hectare
was 738, 788, 550 and 538 in 1995, 1998, 2000 and 2006 respectively, and in the other years it was from 200 to
390. This gives us a presumption that every two or three years this site produces a large number of new culms
except the case of 2003 (Table 4). The distribution of new culms diameter (Figure 1) shows a lot of thin culms
probably because of unmanaged condition. All of these culms are short and impossible to form forest canopy.
The average of diameters was smaller on every following year of the year when bamboo forest produced large
number of new culms.
The age structures of every diameter of surviving culms in the spring of 2003 and 2007 are shown on Figure 2
and Figure 3, respectively. The average diameters of all culms in each year were 6.39 cm and 6.34 cm
respectively. The diameter of a large quantity of culms is from 6 to 8 cm, and there are a lot of culms more than
11 years old. The diameter of main culms forming the forest canopy was more than 6 cm. On the other hand,
thinner the culm was, shorter its longevity was. The culms with comparatively long longevity were more than 3
cm culms in diameter, and the culms of diameter less than 2 cm had extremely short longevity. This is also
understood by the smaller average diameter of new culms on every year than those of surviving culms in 2003
and 2007.
VIII World Bamboo Congress Proceedings Vol 4-141