Hikobia 10: 119-128. 1988

Succession of Pinus thunbergii forest on coastal dunes,Hitotsuba Coast, Kyushu, Japan

Hirosi Taodaaf Pinus thunbergii forest on coastal dunes, Hitotsuba Coast, Kyushu, Japan Hrnosr Taooe

Introduction

Pinus thunbergii forest is the most commonforest vegetation on coastal dunes in the warm-temperate zone of Japan. Most of these forestshave been planted artificially. They are ex-pected both to fix the sand and to break thewind. The history of the afforestation on coast-al dunes is very old. Some of them were main-tained more than three hundred years under thesilvicultural controls of local government. Pin-us thunbergii seems to be the most suitable spe-cies for planting on the sand dunes, because itis very tolerant to both the drought of soil andthe violent wind with salt. It also grows natu-rally in the coastal area. Natural Pinus thun-bergii forest, known as Plzus thunbergii-Pittos-porwn tobira community (sociation ) is com-monly found on rocky coast (Yoshioka, lg58).

Hitotsuba Coast is one of the most famouscoasts with developed pine forest in Kyushu.The oldest stand was afforested more than onehundred years ago. The afforested area is underthe silvicultural control of both the ForestryAgency and the Prefectural Government. Thou-

Tnoon, H. 1988. Succession of. Pinus thunbergii forest on coastal dunes, Kyu-shu, Japan. Hikobia 10: 119-128.

Pinus thunbergii forest on coastal sand dunes and natural evergreen broad-leaved forest on old sand dunes were studied. The gradual change of floristicsimilarity among the stands seems to be a series of vegetational successionfrom Pinus thunbergii forest to Persea thunbergii natural forest. A consid-erable amount of fallen leaves (litter) has been raked up and taken out fromthe forest floor to use as compost. A beautiful moss carpet of. Hypnumplurnaeforme developed in the stands with no fallen leaves. The successionalchange in these stands is very slow and sometimes retrogressive even after thedestruction of the tree canopy by the pine wilt disease.

Hirosi Taoda, Kyushu Branch, Forestry and Forest Products Research Insti-tute, Ministry of Agriculture, Fisheries and Forestry, I 1- I G Kurohami- 4,Kumomoto 860, Japan; Present Address: Research and Extension Diuision,Forestry Agency, Kasurnigasehi 1-2-1, Chiyoda-hu, Tohyo 100, Japan.

gh it has been maintained carefully, pine wiltdisease, caused by a certain Nematoda (Kiyoha-ra & Tokushige, 1971; Mamiya & Kiyohara1972), killed a considerable number of pinetrees in the last two decades.

Coastal pine forest is very important not on-ly as a shelter belt but also in landscaping thecoast. In spite of the effort of the officers, tocontrol the vector insect, it is difficult to pre-serve the pure pine forest. It is desirable to in-duce the artificial pine forest to a more stableforest type. This paper describes the process ofvegetational succession of pine forest in Hito-tsuba Coast, and refers to the principle ofmaintenance of it.

Area investigated

Hitotsuba Coast is located just north of Mi-yazaki City, southeast of Kyushu island. Theclimate of this area is warm and moderate.The annual mean temperature is 16.8'C, the dai-ly mean temperature of the hottest month (Au-gust) is 26.9'C, and that of the coldest month(January) is 6.7"C. The annual precipitation is

t20 Hikobia Vol. 10, No. 2, 1988

about 2600 mm, usually without snow.Natural vegetation on the sand dunes of this

area consists of the communities of Ischaemumantlrcphoroid,es, Viter rotwtdifolin and othergrasses. Among these communities, 2-year-oldseedlings of Pintrc thunbergii have been.planted,sometimes with Robinia pseud,oocacio, Elaeag-ruts urnbelloto, and Myrira rubra. The densityof planted seedlings may be about 10,000 perhectare. It is not easy to make well-developedforest. The forest of today is the result of suchefforts as putting a wind breaker fence aroundthe seedlings, and planting again and again.The afforested area has been expanded into 15km long and 200-600 m wide. A considerablearea of forest floor has been cleaned up by thefarmers, who have raked out fallen leavesevery winter for making compost for cultivat-ing tobacco plants.

There is another type of forest on the oldsand dune. It is the holy forest around a shintoshrine. It consists of Persea thunbergii and oth-er evergreen broad-leaved trees. This forestseemed to be a climatic climax forest. FigureI shows the vegetation of the investigated area.

Methods

Vegetational investigation was made in thesummers of 1982 and 1983. Nineteen stands ofPinus thunbergii forest, four stands of holyforest, and one stand of natural pine forestwere investigated. Braun-Blanquet cover-abun-dance value and sociability are estimated andrecorded for each species in the recognizedcommunity layer of a stand. The vegetationaldata obtained were tabulated and rearranged toemphasize the successional changes. Althoughfactor analysis and the other numerical meth-ods supplement the table method, the final ar-rangement of the table is decided by the num-ber and the ecological status of differentialspecies.

The effect of disturbance of undergrowth byraking up the fallen leaves was considered. Thedevelopment of a moss carpet of Hypnurn plunr.-aeforrne must be correlated with the amount offallen leaves. It is, however, very difficult torepresent the intensity of raking.

Results

Some examples of sand dune vegetation are

P i n u s t h u n b e r g i i

p l a n t e d f o r c s t

P e r s e a t h u n b e r g l l

f o r e s t

S a n d d u n e

P a d d y f i e l d

A r a b l e I a n d

L a w n ( g o l f c o u r s e )

R e s i d e n t i a l a r e a

Road

Fig. 1. Map showing the vegetation and the location of investigated stands.A, F32?. B, F254-256 and F269. C. F268 and F326. D, F259-262,F270 and F330. E, F257-258.G, F263-266. H, F267.

ffiffi[rl1 . . : l

t - - - - t

l - - - it - - - l

ffiHry

)

Hrnosr Taoon tzl

shown in Table l. These communities are com-mon in the coastal sand dunes of Kyushu (Mi-yawaki, 1981). The seedlings of Pints thunber-gii have been planted under the same circum-stances. This is the starting point of the suc-cession. The vegetation (relev6 data) of Pinusthunbergii stands and Persea thunbergii standsis shown in Table 2. The arrangement of relev6sand species is decided by tabular comparison(Mueller-Dombois & Ellenberg, lg74) with theaid of mathematical treatment.

Stand age and, deoelopment of the layers

In about 2O-year-old stands, pine trees havegrown to about 4-5 m high, and the forest crownhas been closed. No woody species is found ex-cept Robinin pseudoacocin planted togetherwith the pine. The herb layer is also poor, withscattered plants of Vitex rotundifolia, Isclne-trlutrr anthephorioid,es, Miscanthrzs sizensis, andItnperata qtli.rdrico var. hoenigii. They are theremains of sand dune vegetation. The mosslayer, consisting of Hypnum plumaeforrle, cov-ers 60-80 percent of the area on the sunny floorand about l0 percent on the rather dark floor.

In the stands of fifty years old, tree layerand subtree layer are differentiated. The heightof the layer reaches about l0 m and 3-5 m res-pectively. Subtree layer consists of. Robiniapseud,oacacia and Pinus thunbergii. Such shrubsas Syrnplocos lucida, Ligustrum japoni.curn,Vaccinium bracteatum and the others have pen-etrated into the forest floor. Loplntherurngracile and Lespedeza cuneata have invaded theherb layer. Fallen leaves are rakied up andtransported out of the forest in the most ofthe stands every winter. H and A-horizons ofsoil are very thin and coverage of the mosslayer is high in these stands (Figs. 2 and 4).Seedlings of tree species are not found exceptPinus thunbergii. In the stands of more thanfifty years old and with no raking of fallenIeaves, the herb layer has developed and themoss layer is poor. H-horizon and A-horizonof soil is 2-3 cm and more than 5 cm thick, re-spectively (Figs. 3 and 5 ). Such perennial herbsas Ophiopogon jaburan and, C,arex lcnta haveentered.

Pine forests have been often damaged by pinewilt disease. Two types of succession are ob-served when the forest canopy has been broken.The one is the rapid growing of under story

Table 1. Natural vegetation of mobile sand dunes

Tab]e number

Tota l cover o f herb layer ( f , )He igh t o f herb layer ( . r )

A r e a ( ^ 2 )

90 90 6020 20 15

1 . 0 1 . 0 1 . 0

an

1 51 . 0

Vi tex ro tund i fo l ia HDig i ta r ia t imorens is HIschaemum anthephroides HlJedeL ia p ros t ra ta HC a r e x s p . HImpera ta cyJ . indr ica var .

k o e n i g i i H i . 2Carex kobomugi H

broad-leaved species, and the other is the natu-ral regeneration of Pinrs thunbergii forest. Thefirst type is found in the stands, which left asnatural, have low density of pine tree and abun-dant undergrowth. The second type is found inthe stands where the undergrowth has been af-fected by raking up the fallen leaves out of theforest floor. Thus, many seedlings of pinetrees are found under the canopy gaps.

Index of successional contirunm

Indexes showing the successional stage wereobtained by two methods. The first one is basedon the floristic composition. The constituentspecies are classified into the following threegroups: Group A consists of the species of sanddune vegetation and man-made pine forest.Group B consists of the species of the deciduoussecondary forest (deciduous Quercus coppice,etc. ) or in natural pine forest. This is the in-termediate of the groups A and C. Group C con-sists of the species growing in the evergreenbroad-leaved forest. Others are species of lowfrequency.

The proportion of the group in each relev6was calculated. The total proportion of groupA (lC, index of coastal pine forest flora) variesfrom 0.0 to 0.87. This value seems to correlatewith the stand age. [t may also correlate withthe distance from sea. The younger stands arelocated nearer the sea shore than the olderstands. The proportion of group B was between0.0 and 0.33. Although the value was high inthe young stands of pine forest, no more spe-cific character is found. The proportion ofgroups C (lE, index of evergreen broad-leaved

5 . 4 5 . 4+ +

1 . 2 3 . 4 4 . 43 . 2 2 . 2

i +

L22 Hikobia Vol. 10, No. 2, lg88

Fig. 2. An inside view of a stand with raking. Fallen leaves (litter) are raked up andbrought out of the forest in winter.

Fig. 3. An inside view of the stand with no raking. Shrub and herb layers are welldeveloped.

l

r23HIRosr Tnoorr

forest flora) seem to be closely correlated withthe stand age. It varies from 0.0 to 0.85. FiS-ure 6 shows the corrrelation between IC and IE.

The second index is based on multivariateanalysis. Factor analysis is applied to such acorrelation matrix, as the correlation coeffi-cient (RaU : Covariance (a,b),/(Standard devi-at ion(a) X Standard deviat ion (b) ) and theJaccard's similarity index (Sab : Number ofcommon species(a,b),lTotal number of species(a,b) ). The calculat ion is based on the pre-sence,/absence data of 7l species in 21 relev6s.The species found only in one releve are omit-ted from the consideration.

A satisfying solution of factor analysis isgotten based on the Jaccard's similarity matrix.Factor loadings of relevds that are estimatedby the squared multiple correlation method andthe non-iterated solution are used as the in-dexes. The position of each relev6 on the planeincluding the co-ordinates of factor 1 and fac-tor 2 is arranged in a curved line. The valuesof the first factor were high in the young standsand those of the second are high in the old Pinusstands and Persea stands. The values of thethird factor are high in the relev6 s of middle-aged stands. Though the relevd s were locatedon a line that shows an ordination of successive

change, it is not a straight line. It must be oneof the faults of the numerical methods ("arch

effect" of Hill and Gauch, 1S0). A new axis(S)was drawn to give a 45" angle with the first andsecond ones. A perpendicular line was drawnto the new axis from each relev6 as shown inFigure 7. The position of a relevE in the newaxis can be calculated by the formula CSn :

f 2n - f l n ( va lue i n -1 .0 t o 1 .0 ) . I t may bethought to be "a

coefficient of succession" ofeach stand. The same solution with the correla-tion coefficient is not suitable, because the posi-tion of relev6s is arranged in such a stronglycurved l ine (bel l-shaped). This is not a standardapplication of factor analysis (Dagnelie, 1978for example ). ttre multivariate analysis isused only as a tool that supplements the tablemethod.

The indexes obtained by the floristic composi-tion were combined to a new index by the sameidea as above (ISn : IEn -ICn). Figure 8 showsthe close correlation of IN and CS. The floristicindex of succession IS seems to be a good indexto show the successional stage in the coastalpine forest. It is not an absolute value, but arelative value usable in the limited area only.The results of floristic analysis and factor ana-lysis are shown in Table 3. The other succes-

Fig. 4. A profile of soil of the stand with raking.Developed moss layer and thin H and A-horizonsare shown.

Fig. 5. A profile of soil of the stand without rak-ing. Accumulated L and F layers and developedH and A-horizons are shown.

L24Hikobia Vol. 10, No. 2, 1988

sional indexes, such as the degree of successionthat is calculated with the life span, dominance,and ground cover of component species (Numa-ta, 1966), has been calculated. The values ob-tained are not appropriate, because the vegeta-tional data used is rather qualitative thanquantitative.

Based on my results, I classify the vegetationof pine forests planted on Hitotsuba Coast intofollowing three groups.

l. Young group. Therelev6sof youngstandscontaining the species of coastal vegetation(Nos. l-5 in Table 2).

2. Middle-aged group. The relev6s containingthe components of the secondary evergreenbroad-leaved forest (Nos. 6-10 in Table 2). ttreforest floor is covered by a moss, Hypnum plu-maeforme. In these stands, the fallen leavesare raked out every winter and the growth ofthe shrub and herb layers are reduced.

3. Old group. The relev6s containing manycomponents of the evergreen broad-leaved for-est (Nos. 11-16, in Table 2). ttre shrub and herblayers are well developed. The forest floor isusually covered with a grass, Loplntherumgracile.

The vegetation of holy forest around a shinto

shrine is broad-leaved evergreen forest, consist-ing of Persea thunbergii and Litsea lancifolia.It seems to be a climatic climax forest devel-oped on the old sand dunes. The floristic com-position of the natural pine forest of Pinusdensiflora is similar to the Persea thunbergiiforest.

Discussion

Pinus thunbergii forest on sand dunes in theHitotsuba Area seems to change to the Perseathunbergii forest, the same as the pine foreston the alluvial plain in central Japan (Kurauchi,1953). Kurauchi reported that Pinus thunbergiiforest with Persea thunbergii as undergrowthare found in stands of 60 to 300 years old, andthe Persea type forest, with Pinus thunbergii,are found in 300-500 years old stands. The old-est planted forest in Hitotsuba coast is about100 years old. These stands are now dominatedby Pinus thunbergii, and the height of evergreentrees reaches to the subtree and shrub layers.This type of forest, Pinus thunbergii-Persea(Machilus ) thunbergii association, is widelydistributed in south western Japan (Yoshioka,1958; Ishizuka, 1974).

o

o

FI

Loc)ctl

lu"%

Fig. 6. Scatter diagram showing the correlationbetween the floristic index of coastal pine forest(IC) and the floristic index of evergreen broad-leaved forest (IE).

.9.

O j oa O

Fig. 7. Scatter diagram showing the result of fac-tor analysis of releves based on Jaccard's simi-larity index and the coefficient of succession de-rived from the factor loadings.

.'''--.

Hrnosr Tnoon

Table 3. Floristic analysis and factor analysis

t25

Re1ev6f lor ist ic index

rc* IE** IS*** f l

factor loading

t 2 f 3 communality CS****

F269 0.gg 0.0 -0.99F262 0 .83 0 .0 -0 .93F255 0 .56 0 .0 -0 .56F327 0 .62 0.0 -0 .62F260 0 .69 0 .0 -0 .69F26l 0.54 0.09 -0.46F254 0.50 0. 10 -0.40F259 0. 53 0.27 -O .26F326 0 .29 0 .2L -0 .09F268 0 .40 0 .33 -0 .07F330 0 . 19 0 .23 0 .04F329 0 . 17 0 .22 0 .05F 2 5 8 0 . 3 1 0 . 3 8 0 . 0 7F 2 7 0 0 . 1 3 0 . 2 3 0 . 1 0F257 0 . 13 0 .43 0 .30F256 0 . l g 0 .54 0 .36F267 0 .0 0 .55 0 .55F266 0 .0 0 .95 0 .95F263 0 .0 0 .65 0 .65F265 0 .0 0 .70 0 .70F 2 6 4 0 . 0 0 . 7 7 0 . 7 7

0 .709 0 .003o . 7 2 L 0 . 0 2 10 . 5 3 1 - 0 . 0 2 10 . 4 1 0 0 . 0 0 10 .448 -0 .0230 . 4 1 9 - 0 . 0 1 50.465 -0.O74o .296 0.0090 .307 0 .o920 . 3 1 0 0 . 1 1 60 .L27 0 ,Lz Io .2 r7 0 .0910 . 2 4 9 0 . 1 4 60 . 0 7 8 0 . 1 3 70.o22 0.2960 . 0 3 3 0 . 3 5 3

-0 .023 0 .555-0 .006 0 .6190.007 0 .6230.020 0 .629

- 0 . 0 1 5 0 . 7 0 3

0 . 5 1 2 - 0 . 7 0 6o .525 -0 .7000 .340 -0 .5520.259 -0.4900.221 -o.47I0 .250 -0 .4330 .503 -0 .5390 .337 -0 .2760 . 2 7 9 - 0 . 2 1 50 . 3 9 8 - 0 . 1 9 4o .263 -0.0060.243 -0. 136o .326 -0 .1030 . 3 1 4 0 . 0 5 90 . 4 2 2 0 . 2 6 40 . 4 5 6 0 . 3 2 00 . 3 8 2 0 . 5 7 90 . 391 0 .6240 . 3 9 3 0 . 6 3 00 . 4 1 9 0 . 6 0 90 . 5 0 4 0 . 7 1 9

0 .0950 . 0 7 50 . 3 4 00 . 1 3 40 . 1 4 00 . 2 7 40 . 5 3 00 . 5 0 6o . 4 L g0 . 5370.4820 . 4 3 60 .4920 . 5 3 70 . 5 8 30 . 5 7 5o .27 I0 .0990 . 0 6 50 . 1 5 30 .096

* index of coastal pine forest flora** index of evergreen broad-leaved forest flora

*** florictic index of succession: IS" : IF, - LC",t:t** coefficient of succession: CS, : f.2^See the detailed explanations in text.

The matured or self-fertilized soil of the pineforest enables the indigenous species to grow inthe forest floor. The progress of soil maturityin these forests is similar to Kawasaki & Tana-t<a (tg84). In some stands, pine trees are killedby the pine wilt disease. These stands look likethe scrub of broad-leaved species, and they mustchange to the climax forest even if it takes along time.

The other case is observed in the pure pinestands in which fallen leaves are raked up. [nthese, if the tree layer is broken down, a lot ofseedlings of pine trees grow up soon; then natu-ral regeneration of pine forest is observed. Itis characteristic that these stands have no herblayer, and have a well-developed moss layer.The retrogressive or cyclic succession of pineforest is closely related to the maintenance ofthe forest (raking). The schematic diagram of

f l "

the two courses of succession is shown in Fig-ure 9.

It may be the principle of maintenance of thepine forest to take off the fallen leaves fromthe forest floor. It leaves the soil too poor forgrowing the broad-leaved evergreen trees. It issuitable for developing the moss layer of Hyp-nurn plum,aeforrne and for growing the pinusthunbergii seedlings. This type of forest is un-stable against diseases, but very tolerant to theconditions of sand dunes. So many broad-leaftrees can invade and grow in the case when fall_en leaves are left and accumulated as litter onthe forest floor. It takes a long time to devel=op on effective shelter belt, because the growthof broad-leaved trees depends on the develop-ment of soil maturity more than does that ofthe pine trees. The author proposes the combi-nation of treatments, for the sea-side half of

126 Hikobia Vol. 10, No. 2, 1988

the afforested area and for the inside half. Thefirst one is to allow the raking and to maintainthe pure pine stands. The other is to prohibitthe raking, and to introduce the broad-leavedtree species for accelerating the succession.

Acknowledgement

I am grateful to Professor Janice M. Glime,Michigan Technological University, for her read-ing the manuscript.

Literature cited

Dagnelie, P. 1978. Factor analyses. In R. H. Whit-taker (ed.), Ordination of Plant Communit ies.pp.215-238. Dr W. Junk, Hague.

Gauch, H. G. 1982. Multivariate Analysis inCommunity Ecology. 298pp. Cambridge Univ.Press, Cambridge.

Hil l , M. O. and H. G. Gauch. 1980. Detrended cor-respondence analysis: An improved ordinationtechnique. Vegetati o 37 : 42-58.

Ishizuka, K. L974. Maritime vegetation. In M. Nu-mata(ed.), The Flora and Vegetation of Japan.pp. 151-172. Kodansha, Tokyo.

Jaccard, P. 1901. Distribution de la flore alpinedans le Bassin des Dranses et dans quelques

regions voisines. Bull. Soc. vaud. Sci. nat. 37:24t-272.

Kawasaki, Y. and K. Tanaka. 1984. On the grow-th of the Japanese black pine (Pizus thunbe-rgii Parl.) and the time-serial transition in thesoil characteristics within the coastal sand-dune fixation forest. Bull. Tottori Univ. For.14: 59-125.

Kiyohara, T. and Y. Tokushige.l97l. Inoculat ionexperiments of a nematoda, Bursaphelenchussp., onto pine trees. J. Jpn. For. Soc. 53: 210-2r8.

Kurauchi, I. 1953. Development of Machilus f.or-est on al luvial plain. BuIl . Soc. Plant Ecol. 3:t2t-t27.

Mamiya, Y. and T. Kiyohara.1972. Descript ionof. Bursaphelendus lignicolus n. sp. (nematoda:Aphelenchoidiae) from pine wood and histopa-thology of nematode-infested trees. Nematolo-gial8: L20-124.

Miyawaki, A.(ed.) tg8f. Vegetation of Japan. 2.Kyushu. 484pp. Shibundo, Tokyo.

Mueller-Dombois, D. and H. El lenberg. 1974. Ai-ms and Methods of Vegetation Ecology, 547pp.John Wiley & Sons, New York.

Numata, M. 1966. Some remarks on the methodof measuring vegetation. Bull. Marine Lab.Chiba Univ. 8: 71-78.

Yoshioka, K. 1958. Ecological Studies of Japa-

I

o

Oa

o

0-

o(o(oq,IQ)=u,

t- '5oxq)

ttE

I

aA

L.o

o

jO

- .5 0 .5

coef f ic ient o f success ion ( C S )

Fig. 8. Scatter diagram showing the correlation between the floristic index of succes-sion (IS) and the coefficient of succession (CS).

Hrnosr Tmoe

nese Pine Forests. 198pp. Nippon Ringyou Giju-tsu Kyoukai, Tokyo (in Japanese).

t27

Received 10. V. 1988.

t ty l o c 'y ' -29}ruvl t t 9 o l l l l l Naturat vegerar ion

Iwind breaker V

* i l t f t r n l * + r * $ l * l

Jfr,+#,+,+,f,*.#

Middle aged stands

Plant ing of

Pinus thunbergii

Young stage of pine forest

and herb layersmoss layer

\

r

I# v tt u| + | aroren forest canopy

.t.1..**.*. .r , i . .Tr.+...**. r .rol* bv pine wil t disease

Generation seedling

Natural regenerated pine forest

.@-tsgL

Fig. 9. Diagram showing the succession of Ptnus thunbergii forest planted on coastal sand dunes.

o f

J

raking the fallen leaves

development of

wi thout raking

.1,

128 Hikobia Vol.

垰田宏:宮崎県一つ葉海岸のクロマツ林の遷移移

宮崎県一つ葉海岸の砂降卜に植栽されたクロマツ林は

最も古いもので約 100年生である。近年、まつくい虫の

被害が見られ、場所によっては広葉樹林化しつつある。一方、天然更新によってクロマツ林が再生している場所

もある。付近の古い砂岳卜に存在する社叢林の調査結果

と合わせ、クロマツ植林からタブ林への遷移過程を明ら

かにした。

50年生以上のクロマツ林には、多数の常緑広葉樹林の

要素が侵入し、階層構造が発違する。クロマツ林とタブ

林の種構成の類似度は連続的であり、クロマツ林からタ

ブ林への遷移が認められる。これは、中部地方で報告さ

れた例と同様である。多くの場所では、タバヨ耕作に用

いる堆肥作りのため、 「落葉かき」が的 れている。

これは、落葉の堆積と低木層、草本層の発達を妨げ、林

床にハイゴケ群落を発達させる。このような林分では、

10,No.2,19鶴

林齢にかかわらず、遷移の進行がおくれ、まつくい虫の

被害により生 じたギャップにはクロマツ稚樹の発生が顕

著である.

Jaccardの 植生類似度をもとに因子分析を行い、2つ

の因子負荷量から、遷移系列に直線的に対応する遷移度

係数を算出した.ま た、林分を構成する植物の生態的位

置づけから、遷移度を示す指数を得た.常 緑広葉樹林要

素と海岸植生要求の構成率の差が最も良い遷移度指数で

あった。

クロマツ植林を、まつくい虫被害に強いタプ林に誘導

するためには、落葉かきを厳禁する必要がある。しかし、

塩風に対する耐性、防風林としての諸機能の点ではクロ

マツ林が優れている.し たがって、汀線側では落葉かき

を行って、クロマツ林の自己修復機能を維持し、内陸側

ではそれを禁止して、遷移の促進をはかることが望まれ

る。

・●β