関東森林研究 68‑2(2017)

論 文

Natural distribution of Pterostyrax hispida under the tree canopies ofartificial Larix leptolepis stand

カラマツ人工林冠下におけるオオバアサガラの分布状況
Iwao UEHARA *１
上原 巌 *１*1 Forest Science, Tokyo University of Agriculture，Setagaya, Tokyo 156-8502*1 東京農業大学 森林総合科学科
Abstract: Pterostyrax hispida sometimes grows in colonies under the artificial Larix leotolepis stands in the Kanto districts orCentral part of Japan. This study researched the natural distribution of Pterostyrax hispida at artificial Larix leptolepis stands in the800 to 900 meters altitude in the Okutama Training Forest of Tokyo University of Agriculture. The Pterostyrax hispida colonies
were often luxuriant under the Larix leptolepis tree canopies, but they were decreased under the Criptomeria japonica andChamaecyparis obtusa canopies. The growth of Pterostyrax colonies also showed proportion with the tree height difference between
Pterostyrax and Larix, or growth of the tree canopies of Larix. Those conditions must be suitable for Pterostyrax growth, because
the light condition were profitable for them. However, growing in colonies of Pterostyrax restrained the other woody plants underthe tree canopies of Larix. At the clay soil stands, the average height of Pterostyrax was low and their colonies decreased, too. It
also showed the Pterostyrax has possibility as an indicator of soil condition.
Keywords: Pterostyrax hispida, Larix leptolepis, colony, tree canopies, indicator
要旨：関東や中部などの内陸のカラマツ人工林において，その林冠下には，落葉広葉樹のオオバアサガラ（Pterostyrax
hispida Sieb. et Zucc.：エゴノキ科）の群生が見受けられる。本研究では，東京農業大学・奥多摩演習林内の標高 700〜1000ｍ前後の複数のカラマツ林分において，その林冠下におけるオオバアサガラの分布状況を調べた。調査の結果，カラマツ林冠下でオオバアサガラは繁茂，群生をするものの，スギ・ヒノキ林冠下では減少することが確認された。
また，上木であるカラマツとの樹高差が大きく，カラマツの林冠形成が大きいほど，オオバアサガラの群落形成および個々の受光および生長に有利であること，オオバアサガラの繁茂状況が他の下層植生樹木の生育にも影響を与えることがうかがえた。さらに，埴土質の土壌ではオオバアサガラは樹高が低く，群落形成も困難であったことから，森林土壌の土質を示す指標植物としても使用可であることが推察された。
キーワード：オオバアサガラ・カラマツ・群生・林冠・指標植物

Ⅰ．Introduction
Pterostyrax hispida sometimes grow in colonies under theartificial Larix leotolepis stands in the Kanto districts or Central
part of Japan（Fig.1）. It has been known as one of the deer
dislike woody plants (３, 4）. Therefore, the colonies are foundin the high deer density under the artificial tree stands, too（1,2）.
However, it has not been cleared how they are distributed
naturally under the artificial tree stands conditions exactly.
Therefore, this study researched the natural distribution ofFig.1 Pterostyrax hispida under the Larix leotolepis stand in thethem under the artificial Larix leptolepis canopies.

Kita-aiki village in Nagano Prefecture−217 −（受理日 2017 年 8 月 1 日）

Ⅱ．Method
This survey focused on three artificial Larix leptolepis stands
in the Okutama Training Forest of Tokyo University ofAgriculture, located in Okutama region of Tokyo. It is situatedat lat. 35°49′2’’ N. and long. 139°4’ 45’’ E. The
surveyed stands were located in 800 to 900 meters high abovesea level.
Stand A was poor results stand of Larix leptolepis, located in
850 meters high above sea level. The stand slope was 5 degreeand face north direction. Soil texture was mainly clay.
Stand B was another Larix leptolepis stand located in 900
meters high from sea level. The stand slope was 15 degree andFig.3. Tree canopies projections of Stand A

face north direction. Soil texture was loam and clay loam. It was（× Pterostyrax stock)

also stony.
Stand A and B are approximately same age.
Stand C was mixed forest of Criptomeria japonica, andChamecyparis obtusa just nearby Larix stand. It was located inapproximately 840 meters high above sea level, the stand slope
was 15 degree and faced north direction. Soil texture was stony.
The area of each survey plot was 100 ㎡. I drew the tree
canopy projections of each stand and measured the tree height,
diameter at breast height, and density per a hectare of Larix
leptolepis and Pterostyrax hispida. The relatively light intensity
was measured under the Larix crowns but not under the crowns

Fig.4. Tree canopies projections of Stand Bof Pterostyrax hispida. I also checked SPAD (Amount of（× Pterostyrax stock)

chlorophyll) of leaves of Pterostyrax hispida. I checked 5 times
a leave and repeat 6 leaves per a stock.

Fig.5.Tree canopies projections of Stand C（× Pterostyrax stock)Fig.2 Measuring SPAD from leaves of Pterostyrax hispida.

Table 1 shows the condition of each stand. The growth of highstory of Stand B was the biggest and the density of Pterostyrax

Ⅲ．Results and discussion

was also the highest. Average relative light in density of Stand

Tree canopies projections of stand A to C are shown on Figure

A was high, but the growth and density of Pterostyrax was low.

3 to 5.

It suggests Pterostyrax colony was influenced by other factors
beside the light condition, although it is shade intolerant tree.

−218 −

関東森林研究 68‑2(2017)

Table 1. Conditions of Stand A to C
Stand A

Stand BHigh story average tree height （ｍ）

13.1 (±4.0）20.3（±4.0）

15.0（±0.4）High story average crown height （ｍ）

5.0（±0.8）8.2（±1.7）

4.6（±1.2）

High story average DBH （cm）

18.0（±3.7）36.7（±5.6）18.1（±4.9）High story average canopies area （㎡）8.2（±3.3）

15.9（±5.6）7.0（±1.7）

700

600

800

Pterosｔｙrax a verage tree height (m)2.5（±1.6）

3.3（±3.1）

1.4（±0.7）

Pterosｔｙrax a verage DBH (cm)2.3（±2.0）

5.9（±1.8）

1.1（±0.8）

Pterosｔｙrax a verage canopies area (㎡） 4.6（±3.3）

8.0（±1.0）

4.5（±2.9）

High story density per a hectareStand C

Pterostyrax density per a hectare

7002800

1100

Average relative light intensity （%)

25.0（±8.2）

7.2（±1.6）

5.0（±1.4）

Fig.8. Soil profile of Stand C

Next, the soil profiles of each stand are shown on Fig.6 to Fig.8.
Stand A was that A layer was 15 to 20cm and B layer was 60
to 80cm。The soil texture was mainly clay. Stand B’s A layer

The Pterostyrax hispida colonies were often luxuriant under

was twice deeper than Stand A, and the soil texture was mainly

the Larix leptolepis tree canopies, but they were decreased

loam and stony. Stand C’s B layer was thick, but it had many

under the Criptomeria japonica and Chamaecyparis obtusa

stones. At the clay soil stands, the average height of Pterostyrax

canopies. The growth of Pterostyrax colonies showed

was low and their colonies decreased, too. These results showed

proportion with the tree height difference between Pterostyrax

the Pterostyrax has possibility as an indicator of soil condition.

and Larix, or growth of the tree canopies of Larix. Thoseconditions must be suitable for Pterostyrax growth, because thelight condition were profitable for them.
Advanced Pterostyrax colonies were seen in the Stand B. Not
only the high tree density, but also multi-layered colonies of it
were seen (Fig. 9). On the contrast, Pterostylax stocks weredecreased under the Criptomeria japonica and Chamaecyparis
obtusa canopies (Fig.10).

Fig.6. Soil profile of Stand A

Fig.9. Multi-layered colonies of Pterostyrax of Stand B

Fig. 10. Floor vegetation condition of Stand C

Fig.7. Soil profile of Stand B−219 −

Average amounts of SPAD of Pterostyrax are shown on theFig.11. SPAD data of Stand A with the highest light intensity

6SPAD

was the highest.

R = 0.7978

54

Stock numbers

40353025201510503210-1 0102030

High story canopies area (㎡）

Fig.13. Relation between high story canopies area and number

Stand A

Stand Bof Pterostyrax hispida

Stand C

Fig.11. Agerage amount of SPAD of Pterostyrax of eachstandsⅣ．Conclusion
Pterostyrax hispida is a kind of shade intolerant tree (1,2,3,4).
They make colonies under the artificial Larix leptolepis stands

Canopies area of high story and Pterostyrax and its numberswith good soil condition. Especially, broad Larix canopies

are shown on Fig.12 and relation between high story canopies

condition is suitable for their growth and making colonies. But

area and number of Pterostyrax hispida is shown on Fig. 13.

they cannot make colonies under the Larix canopies at the clay

Relation between canopies area of high story and undersoil stand, even with the suitable light condition. Therefore,

Pterostyrax, and high story canopies area and numbers of

Pterostyrax can be possibly an indicator of soil condition.

Pterostyrax was correlative (r=0.8466).

However, controlling them on the floor of artificial Larix stands

However, growing in colonies of Pterostylax restrained theis another assignment.

other woody plants under the tree canopies of Larix. Therefore,
at artificial Larix stands, controlling Pterostyrax is important for

Literature cited

keeping diversity of vegetation.

(1) Nishio, K., Kabutomori, S., Sugawara, I., Uehara, I., Sato,A.(2009) Germination and fruit characteristic ofPterostyrax hispida. Journal of the Japanese Forest

30（㎡）、stock numbers

25201510
50Stand CStand AStand BHighstorycanopiesarea(㎡）Pteros
tyrax
canopiesarea(㎡）
Pterostyrax
numbers(Stocks)

Society 91(4):295-298.
(2) Takahashi, Y., Nishio, K., Sugawara, I., Uehara, I., Sato, A.
(2009) A study on the length of slip and rooting promotion
method influences by cutting of Pterostyrax hispida.
Journal of Agriculture Science, Tokyo University ofAgriculture 54(1):51-58.
(3) Takahashi, Y., Sugawara, I., Uehara, I.,Sato, A.(2009) The
coppices characteristic of Pterostyrax hispida in three
years from felling. Kanto Journal of Forest Research
60:87-90.
(4) Nishio, K., Takahashi,Y., Sugawara, I., Uehara, I., Sato,A.(2009) Growth in gap and deer browsing characteristicsof Pterostyrax hispida. Kanto Journal of Forest ReseachFig.12 Canopies area of high story and Pterostyrax hispida

61:89-93.

and its stock numbers−220 −