Creating a Society in Harmony with the Environment z Research Trends & Results

Slope revegetation using forest topsoil
MATSUE Masahiko,Head KUBO Masako,Reseacher
Landscape and Ecology Division, Environment Department
Forest topsoil utilization works, buried seeds, revegetation

1. Introduction
Given the problems of genetic disturbance andproliferation of alien species when introducing plants
for revegetation, local character needs to be taken into
account when selecting plants for public revegetation
works. Meanwhile, buried seeds in forest topsoil
include many of a local character, and are thought fairlyeasy to collect. In light of this, revegetation works
using forest topsoil (forest topsoil utilization works) arethought to present a viable substitute for revegetation
using alien plants. In public revegetation works, it is ofparamount importance to predict the initial state of
growth when judging whether to carry out revegetation
using this method. In this study, therefore, we studied
the initial state of plant establishment achieved in forest
topsoil utilization works.

works with topsoil mixture ratios of 10%, 20% and30%. On slopes 1 and 2, fewer individual plants grew.
This was thought to be because the installation took
place in summer, when not enough germination wasachieved, and also because the topsoil contained a large
quantity of clethra. On slope 3, conversely, the numberof individual plants was large in the first year of
installation but had decreased by the third year. This
was thought to result from compression by goldenrod
and other herbaceous plants. Therefore, when wishingto establish plant colonies quickly, this method may be
unsuitable for use in summer installation and inlocations where there are many alien species nearby.
Vegetation established through revegetation with
forest topsoil is influenced by the slope attributes of theinstallation site and the season of installation, amongothers. We plan to produce guidelines for thisinstallation method, in which we clarify therelationship between slope attributes and vegetation
based on numerous case examples. In this way, thesuitability or unsuitability of use can be judged fromthe conditions of land scheduled for installation in
public works projects.
1

slope1: Summer
installation
法面１：夏施工

0.5
01.5

A hi llsi de pl ant ed with gree nery usi ng forest topsoil (Kyoto )No.ofplants per m2 2
木本個体数/mResearch Trends & Results(Key words)

1

Slope2:Spring installation
法面２：春施工

0.5
0
4.5
4
3.5
3

Slope3:
Spring installation
法面３：春施工

1st year of
施工当年
installation
nd
22年目
year
rd
33年目
year

2.5

A clet hra se edl ing

A sumac se edl in g

Fig. 1 A hillside treated with forest topsoil utilization
works, and examples of plant seedlings
2. Types of buried seeds
Buried seeds mainly exist in around the upper 10cmof forest topsoil; the topsoil of secondary forests isknown to contain many seeds of sumac, mallotus,clethra and others. Although present as buried seeds,
however, clethra and others have a known tendency not
to become established on slopes, depending on theinstallation conditions.
3. Examples of forest topsoil utilization works
We carried out installation experiments on slopes inthree national parks, using forest topsoil utilization

21.5
1
0.5
0zone
10%区

zone
20%区

zone
30%区

Fig. 2 Number of plants growing on each experimental
slope[Bibliography]
D. Hosogi, S. Yonemura, A. Kameyama (2004),
Potential of forest soil seed bank as revegetationmaterial in Kanto district and its examination method,
Journal of the Japanese Society of Revegetation
Technology, 29 (3) ：412-122.