関東森林研究論 文70-2(2020)

Distribution of natural regenerated Lindera umbellata at artificial
Chamaecyparis obtusa floor by several thinning rates

Iwao UEHARA１
１ Tokyo University of Agriculture
Abstract: Thinning cut facilitates natural regeneration of woody species on the forest floor. This research surveyed thenatural regeneration of Lindera umbellata at the floor of artificial Chamaecyparis obtusa stand. It also aimed toreconsider how thinning rate have effects on the distribution of Lindera umbellata. The survey plots were 30%,50%, 70% thinning, and control plot in a 50-year Chamaecyparis obtusa stand and each plot area was 400 ㎡. The averagetree height of Chamaecyparis obtusa was 17.5m, the average DBH was 24cm, and the average crown height wasover 6.5m. The results showed the appearance rate of Lindera umbellata seedlings was 1 to 3% of all seedlings
except Chamaecyparis obtusa. Thinning rate and relative illumination and the tree height had correlation. These
results suggested it has some possibility of forest floor cultivation of Lindera umbellata. There was no correlation
between thinning rate and relative illumination and chlorophyll amount of the leaves of Lindera umbellata.
Key word: natural regeneration, floor vegetation, appearance rate, space dominant, SPAD

間伐率の異なるヒノキ林床におけるクロモジの分布
上原 巌１
１ 東京農業大学
要旨：クロモジ（Lindera umbellata)は、北海道から九州にかけての温帯に自生するクスノキ科の樹木であり、スギやマツなどの造林地の林床でも見られる。しかしながら、スギ、ヒノキなどの人工林において、その立木密度や間伐率の違いによる分布、出現率などについてはあまりよく知られていない。そこで本研究では、東京農業大学・富士試験林（標高約 900ｍ）の 50年生のヒノキ間伐試験林（平均樹高 17.5ｍ、平均ＤＢＨ24cm）において、対照区、30％、50％、70％間伐区の各 400 ㎡の試験区を設け、その林床のクロモジ分布を調べた。調査の結果、クロモジ実生の出現率は１～３％であったが、間伐率および相対照度とクロモジの出現率と樹高にはある程度の相関が認められた。このことから、間伐によって、林床のクロモジの出現や生長をコントロールすることも示唆された。しかし、間伐率や相対照度と、クロモジのクロロフィル量との間には相関は認められなかった。
キーワード：天然更新、林床植生、出現率、空間優先度、SPADⅠ Introduction

species is important. Especially, medical plants are

Thinning cut facilitates natural regeneration on theuseful, economically valuable, and worth as forest

forest floor. Recently, broad-leaf trees regeneration atbiomass, too.

artificial needle-leaf forests floor has become more

Lindera umbellata is a woody plant that can grow onimportant, because it is useful to increase diversity ofthe forest floor of artificial conifer stands. It hasvegetation and sometimes make mixed forests without

characteristic sweet fragrance (1) and produces

planting (2). Natural regeneration is more effective at

perfume and medical liquor. Recently, it has come tothe difficult stands to plant and is easier to adapt themake bath salt, too. Therefore, this research focused onstand condition (2)(3)(4)(5). In addition, in the view of

the Lindera umbellata and surveyed the natural

the point of forestry, how to regenerate the usefulregeneration at the floor of an artificial Chamaecyparis－21 －（受理日 2020 年 2 月 4 日）

obtusa stand. It also reconsidered the effects ofunobstructed sky condition.

thinning by several rates for its growth.
Ⅲ. Results and Discussion
Ⅱ Materials and Methods

1.

1. Site The survey plots were located in an artificial

Table 2 shows the appearing species number and50-year Chamaecyparis obtusa stand in the Fuji

appearance rate of Lindera umbellata of each plot.

Research

2. Average tree height of Lindera umbellate

FarmAreaofTokyoUniversityofAppearing species numbers of each plot

Agriculture. They are located in Susono city of

Next, Fig.1 shows the correlation of thinning rate andShizuoka Prefecture and the altitude is 830m. In

the average tree height of Lindera umbellata.

March of 2001, 30%, 50%, 70% thinning by density

Thinning rate and the average height showed highwere done on the stand. Each survey plot area was 400

correlation㎡ and all stands were mostly flat. Forest soil wasillumination and the average tree height showed

andosol and the soil pH was 3.5 to 4.5. Counting all

correlation, too (r=0.6594).

(r=0.7101).

Inaddition,correlative

regenerated seedling of woody plants in each plot andmeasuring all tree height of each tree (above 0.3m).

Table 2. Appearing species number of each plots

Table 1 shows the outline of surveying plots.
Table 1. Outline of survey plots of Chamaecyparis

Species numbers

obtusa standAppearance rate ofControl

30%

50%

70%

thinning

thinning

thinning

Lindera umbellata (%)

Stand Density (/ha)

1925

750

675

475

Average Height (m)

16.6

18.1

17.1

17.4

Average DBH (cm)

19.9

26

23.8

26.3

61.4

40.7

30.6

26.1

541.39420.42249.77200.41

4.37

6.0111.33

14.22(㎡)
Total Volume （㎥）Relative illumination
(%)

50%

70%

thinning

thinning

thinning

29343128

112332.5

Tree height (m)Total Basal Area

30%Control

2. Appearance rate This research surveyed theappearance rate of Lindera umbellata on each plot was2

y = 0.0168x + 0.6186
R = 0.7101

1.5
10.50

surveyed as the frequency of seedlings among all

0species except Chamaecyparis obtusa. It also surveyed

204060Thinning rate (%)

80

vertical appearance condition of all seedlings higher

Fig.1 Correlation of thinning rate and the average tree

than 30cm from the floor.

height of Lindera umbellata

3. Chlorophyll amount (SPAD) This research also
surveyed chlorophyll amount of the Lindera umbellata

3. Space dominant conditions of each plot

by SPAD-502 analyzer (KONICA MINOLTA) to check

Space dominant conditions of each plot are shown inphysiological activity condition. Measuring twice per aFig.2 to 5. Species over 0.3m height are shown.

leaf and measured 20 leaves in each 50cm story above
the ground.
４． Relative illumination This research measured
relative illumination by measuring illuminance at the1m height from the floor in each stand and－22 －関東森林研究

Clethra barbinervis
Kalopanax septemlobus
Rhododendron kaempferi
Irex macropoda
Magnolia obovata
Acer palmatum
Chengiopanax…
Betula grossa
Lindera umbellata
Cornus macrophylla
Irex crenata
Acer micranthum
Viburnum erosum
Rhododendron kaempferi

（ｍ）

00.5

11.5

Fig.2 Space dominant conditions of control plot
Styrax japonica
Irex macropoda
Clethra barbinervis
Pieris japonica
Lindera umbellata
Hydrangea hirta
Hydrangea paniculataCerasus incisa
Rubus palmatus
Cornus macrophylla
Acer rufinerve
Betula grossa
Carpinus tschonoskii

70-2(2020)

Betula grossa
Lindera umbellata
Cerasus incisa
Clethra barbinervis
Callicarpa japonica
Hydrangea paniculata
Ilex serrata
Fraxinus lanuginosa
Carpinus laxiflora
Acer rufinerve
Irex macropoda
Cornus macrophylla
Magnolia kobus
Rhododendron dilatatum
Rubus palmatus
Rhododendron kaempferi
Enkianthus cernuus
Acer micranthum
Aralia elata
Hydrangea hirta
Irex crenata
Viburnum erosum

0（ｍ）

123

Fig.5 Space dominant conditions of 70% thinning plot
4.Correlative illumination of the places of Lindera

umbellata appearance
Fig.6 shows the average correlative illumination of
the places of Lindera umbellata appearance. The
1.5

percentage in control, 30% and 50% thinning plots

Fig.3 Space dominant conditions of 30% thinning plot

were extremely low. These data suggested thatm00.5

1Lindera umbellata could germinate and grow underIrex macropoda
Hydrangea paniculata
Clethra barbinervis
Lindera obtusiloba
Cerasus maximowiczii
Acer palmatum
Betula grossa
Rhododendron kaempferiLigustrum obtusifolium
Acer rufinerve
Cornus macrophylla
Cerasus incisa
Fraxinus lanuginosa
Lindera umbellata
Callicarpa japonica
Taxus cuspidata
Ilex serrata
Acer micranthum
Zanthoxylum piperitum
Magnolia obovata
Rubus palmatus
Viburnum erosum（ｍ）

the low illumination level at artificial Chamaecyparis

obtusa stand.
Corralativeillumination (%)

86420
Control

30%
50%
70%
thinning thinning thinning

Fig.6 Average correlative illumination of the places ofLindera umbellata appearance（*Error bar means SD）

00.5

11.5

2

Fig.4 Space dominant conditions of 50% thinning plot

5.Chrolophyllamount(SPAD)

ofplots

Chrolophyll amount (SPAD) of Lindera umbellata ineach plot are shown in Fig.7. Significant difference
among the thinning rate was not shown.

－each23 －(SPAD)

correlative illumination and tree height. Lindera

umbellata might thoroughly distribute chlorophyll

40regardless of light condition. It can regenerate by30

sprout, too.

20

Next step is considering how to promote the gwowth

10

or cultivating Lindera umbellata on the artificial forest

0Control30%
thinning

50%
thinningfloor.

70%thinning

Fig.7 Average data of SPAD in each plot（*Error bar means SD）
Next, average data of SPAD of each story are shownin Fig.8. These data also showed no significant
difference among the stories.
These results suggested that Lindera umbellata
Fig.9 Growth of branches of Lindera umbellata undercondition.

the high story tree shade.

(SPAD)

thoroughly distributes chlorophyll regardless of light

50403020
10050cm story

100㎝
story

150㎝
story

200㎝
story

Fig.8 Average SPAD data of each stories of all plots（*Error bar means SD）
Fig.11 Root system of Lindera umbellata
6.Other features Lindera umbellata appeared under

Chamaecyparis obtusa crowns. Fig. 9 shows theReferenceschanging of the tree shape under the crown of(1) Hayashi, Y. (1969) Diagram of useful trees (有用樹

Chamaecyparis obtusa. It branched widely to absorb

木 図 説 ). pp. 255. Seikodoshinkosha. Tokyo. (inlight under the tree shade. This shaping phenomenon
suggested Lindera umbellata has adapting ability forJapanese)(2) Kawahara, T. (1994) Art of tending regenerated

low light condition.

broad-leaf trees at artificial needle-leaf tree stand.

There were sprout regeneration in each plot, too.

Broad-leaf forest practice （広葉樹林施業）． pp.

Fig.10 showed the root system of Lindera umbellata.
Rootlets and hair roots were few.

154-173. Zenrinkyo, Tokyo.(in Japanese)(3) Nyland, R.D. (2016) Silviculture – Concepts andApplications. pp.27-31. Waveland Press, Long
Grove, IL.

Ⅳ．Conclusion
This research showed the appearance rate of(4) Smith, D.M. (1986) The practice of silviculture.

Lindera umbellata was 1 to 3 % under an artificial

pp.45-46，128-129. Wiley, New York.

Chamaecyparis obtusa stand. The space dominance(5) Uehara, I. (2018) Silviculture Field Note (造林学

was from the middle to the high class in the floorフィールドノート). pp.123-133. Corona-sha. Tokyo.

vegetation.

(in Japanese)

Thinning had correlation

withthe－24 －