Ken Ohta

Yoshio Hada

オオタ ケン

ハダ ヨシオ

太田 謙

波田 善夫

Ohta, Ken

オオタ, ケン

Hada, Yoshio

ハダ, ヨシオ

AROUS Academic Repository of Okayama University of Science / 岡山理科大学学術リポジトリ

Naturalistae 16: 19-27(Feb. 2012)- 19 -１．The Botanical Garden, Kake Educational Institution, 1-1 Ridai-cho, Kita-ku, Okayama City, Okayama 700-0005, Japan. 〒700-0005．岡山市北区理大町1-1，加計学園自然植物園．２．Department of Biosphere-Geosphere System Science, Faculty of Informatics, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama City, Okayama 700-0005, Japan. 〒700-0005．岡山市北区理大町1-1，岡山理科大学総合情報学部生物地球システム学科．Original paperThe vegetation on the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan Ken OHTA1 & Yoshio HADA2岡山市足守における花崗岩地域の植生太田 謙1・波田善夫2Abstract: The vegetation developed on the granite rock area was studied phytosociologically at Ashi-mori, Okayama City, S.W. Honshu, Japan.  We recognized 12 communities of forest vegetation and three communities of moor vegetation.  The typical Pinus densiflora community, covering 70% of the study area, was developed mainly on the ridges and slopes.  We described the floristic composition of each communities, and drew a detailed vegetation map based on the recognized floristic communities in accord with the microtopographic data obtained through the field survey.I. IntroductionTo reveal the influence of geological and topo-graphical feature on the vegetation, we investi-gated the vegetation of the granite rock area of  .napaJ ,uhsnoH .W.S ,ytiC amayakO ,iromihsAStudy of the vegetation developed on granite rock area in Okayama Pref. were carried by Ishibashi (1980), and Nishimoto and Hada (1994).  But these report has no vegetation map.  To elucidate the relation between vegetation and geological and topographical feature, we needs an accurate vegetation map.  We aim to draw the precise veg-etation map considering the microtopography.II. Study areaThe study area (Fig. 1) of 3.99 km2 is located at Ashimori, Okayama City, S.W. Honshu, Japan (34°42′ N, 133° 56′ E).  The altitude ranges from 10 to 202 m above sea level.  The climate of the area is characterized by a relatively small amount of rainfall and a warm temperature.  Mean annual temperature is 16.1 °C and annual precipitation is 1,118 mm at the nearest meteorological station of Okayama (Website of the Japan Meteorological Agency).  Geologically, the area is covered only by granite rocks (Mitsuno 1977).III. Methods .7002-5002 ni tuo deirrac erew syevrus dleiFCover-abundance and sociability (Braun-Blan-quet 1964) of all vascular plants were recorded in 73 quadrats (size 100-225 m2  .stserof eht ni )The names of species followed Satake et al. (1981, 1982a, 1982b, 1989a, 1989b) for flower-ing plants, and Iwatsuki (1992) for ferns. Vegetation types were classified on the basis of species composition by phytosociological methods (Braun-Blanquet 1964).  These data were analyzed by the computer program, Veget of Hada & Toyohara (1990). A vegetation map, 2.1 km×1.9 km, were made in 2007 using field surveys based on floristic criteria, establishing whether diagnostic species of each vegetation type were present or absent in the field. IV. ResultsFrom the phytosociological research, follow-ing 15 communities including three communi-ties of moor vegetation were recognized.  Table 1 shows the species composition of forest and moor communities.  Some explanations on those are as follows: © 2012 by Okayama University of Science, PDF downloadable at http://www.ous.ac.jp/garden/- 20 -Ken OHTA and Yoshio HADA Fig. 1. Map showing the location of the study area. The interval of contour lines is 5 m. 1. Vegetation  A. Pinus densiflora sub-tree forest Only the Pinus densiflora sub-tree forest, oc-curring on the rocky sites, was recognized in this forest type.  In the sub-tree layer, Pinus densiflora was dominant, and Miscanthus sinensis was also appeared in the herb layer.  Height of the communities is rather low, 6-8 m, and floristic composition was poor.  B. Pinus densiflora forestIn this forest, following heliophytes occurred, such as Juniperus rigida, Diplomorpha sikokiana, Vaccinium oldhamii and Pinus densiflora.  This forest was divided into the following four com-munities.  Among the communities, the Pinus densiflora typical community covered 70 % of the investigated area, of which height was 7-15 m. a. Pinus densiflora - Miscanthus sinensis com-munityThis community is characterized by the pres-ence of species group 2, 4 and 5 (Table 1). Cov-erage of the tree layer and average number of species was rather small.b. Pinus densiflora-Dicranopteris linearis community Characteristic feature of this community was the dominant of Dicranopteris linearis. After the damage of the Pine disease, D. linearis has grown densely there.  Thick coverage of D. lin-earis inhibits the growth of various herb species or wood seedling. c. Pinus densiflora typical community This community has no character species, but the most predominant vegetation unit in the study area.  d. Pinus densiflora-Quercus serrata com-munityThis community is characterized by the pres-ence of species group 4 and 7 (Table 1). Height of tree layer was 9 to 16 m, heigher than former vegetation unit. It seems to be intermediate stage to Quercus serrata community.  C. Quercus serrata forestQuercus serrata forest is characterized by evergreen broad-leaved tree such as Quercus glauca and Ilex chinensis.  It developes on the valley and gentle slopes of the mountain foot. Average number of the species is highest among the forests investigated.   D. Quercus variabilis forestThis forest was predominant by Querus variabilis in tree layer.  Q. variabilis is decidu-ous broad-leaved tree grown up to more over 15 m.  This forest was developed around village or cultivated land.  E. Quercus glauca forestQuercus glauca is evergreen broad-leaved tree, one of the species occurring in late stage of succession. This forest was developed at shores of pond.  F. Lithocarpus glabra forest Lithocarpus glabra (Fagaceae) is evergreen broad-leaved tree.  Distribution of this species is rare in this area relatively, but constantly found in granite area in western part of Japan.  Community of L. glabra was distributed around the cultivated land.  Lithocarpus glabra in the community was grown up to 16 m in heignt, and to the bust height diameter of 25 cm. - 21 -The vegetation of the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan.Fig. 2. Actual vegetation map of the study area in 2007. - 22 -Ken OHTA and Yoshio HADA Table 1. Plant communities of the study area; granite rock area in southern Okayama, Japan. - 23 -The vegetation of the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan.- 24 -Ken OHTA and Yoshio HADA Table 1. (continued)- 25 -The vegetation of the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan.- 26 -Ken OHTA and Yoshio HADA   G. Pinus taeda plantationPinus taeda is the native species of the south-eastern United States of America. After the prevalent of the Pine disease in Japan, P. taeda was often planted there aiming to resist the Pine disease.  H. Bamboo forestPhyllostachys pubescens was useful plants before the wide use of petrochemical products. Bamboo was used for agriculture and construc-tion materials. Therefore, the forest is usually distributed around the village.  I. Alnus japonica forestSwamp forest dominated by Alnus japonica developed at the watery area around the pond. Height of A. japonica was 13-16 m, and the bust height diameter was about 20 cm.  J. Moor vegetationThe moor vegetation, developed on the granitic area, was developed on the sediment around pond, is characterized by occurrence of wetland plants, such as Isachne globosa and Utricularia racemosa.  This vegetation was subdivided into following three communities. a. Eriocaulon sikokianum - Rhynchospora faberi community Coverage and height of herb layer is smallest in these three communities.  Characteristic spe-cies of this community; Eriocaulon sikokianum is annual, sign of the unstable soil condition.  b. Rhynchospora fujiiana community  This community is characterized by the pres-ence of the species group 19 and 20 (Table 1).  It is main and typical moor vegetation of study area. Height of herb layer was 20 to 60 cm.c. Rhynchospora rugosa community This community is characterized by the pres-ence of the species group 20 and 21 (Table 1). Its developed at marginal area of the moor and watery area around the pond.2. Vegetation map  As the result of the studies, 21 units shown in the legend of the vegetation map were recognized (Fig. 2).V. Discussion  1. Pinus densiflora forestToyohara (1984) studied phytosociologically the secondary pine forests of Hiroshima Pref., and he described vegetation types based on spe-cies composition.  The Pinus densiflora forest, recognized in this study, seems to be similar to the Querco glaucae-Pinetum densiflorae (Toyohara 1984) by the presence of the character species, such as Dicranopteris linearis and Vaccinium bracteatum.Forest vegetation of the granite rock area at the southern part of Okayama Pref. (Setouchi area), has previously been studied by Ishibashi (1980) at Kojima Peninsula, and by Nishimoto & Hada (1994) at Wake-Cho.  The main components of vegetation of the investigated area of Ashimori area seem to be almost common with the formerly studied area, but the cover abundance of Pinus densifolra in the Ashimori is higher than those of other areas.  Moreover, in the Pinus densiflora forest of the Ashimori area, the occurrence of Rhododendoron obtusm var. kaempferi and Vac-cinium bracteatum is higher than other areas.    2. Moor vegetation Plant communities recognized in this moor may be similar to the subassociation Rhyncho-sporetosum faberi (Hada 1984) by the presence of the character species, such as Rhynchospora faberi, Utricularia racemosa, Utricularia bifida and Drosera rotundifolia. Among the known moor vegetation in the southern Okayama Pref., the pond of Akaiwa Oike (Hada 1972) has similar vegetational com-ponents with that of the Ashimori area. Acknowledgements: Special thanks are due to Ms. M. Ida, Mr. K. Okuda and Mr. T. Furuya of Okayama Univer-sity of Science for their help with the field surveys.ReferenceBraun-Blanquet, J. (1964). “Pflanzensoziologie” 3. Aufl. 865 pp. Springer-Werlag.Hada, Y. (1972). The moor vegetation of Akasaka-Oike, Okayama Pref.  Bull. Okayama Coll. Sci. 8: 35-42. (In Japanese with English summary.) Hada, Y. (1984). Phytosociological studies on the moor vegetation in the Chugoku District, S.W. Honshu, Japan.  Bull. Hiruzen Res. Inst. Okayama Univ. Sci. 10: 73-110. Hada, Y. & G. Toyohara (1990). Veget (Computer program for tabulation).  Hikobia-Kai, Hiroshima. Ishibashi, N. (1980). On the vegetation of the Kojima Peninsula, Okayama Prefecture. Bull. Fac. School Education Hiroshima Univ. 3(2): 87-98. (In Japanese with English summary.) Iwatsuki, K. (1992). Ferns and fern allies of Japan.  Hei-bonsya, Tokyo. (In Japanese.) Mitsuno, T. (1977). Subsurface geological map, Okayama-Hokubu.  Okayama Prefecture (ed.) “Land classifica-tion basics investigation” Sjcmap. - 27 -The vegetation of the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan.（2012年１月６日受理）Nishimoto, M. & Y. Hada (1994). Forest vegetation in the Okayama Prefectural Nature Conservation Center 1. Species composition and community structure. Bull. Okayama Pref. Nature Conservation Center 2: 13-24. Satake, Y., H. Hara, S. Watari & T. Tominari (1989a). Wild Flowers of Japan, Woody plants I.  Heibonsya, Tokyo. (In Japanese.) Satake, Y., H. Hara, S. Watari & T. Tominari (1989b). Wild Flowers of Japan, Woody plants II.  Heibonsya, Tokyo. (In Japanese.) Satake, Y., J. Ohwi, S. Kitamura, S. Watari & T. Tominari (1981). Wild Flowers of Japan, Herbaceous plants I. Heibonsya, Tokyo. (In Japanese.) Satake, Y., J. Ohwi, S. Kitamura, S. Watari & T. Tominari (1982a). Wild Flowers of Japan, Herbaceous plants II.  Heibonsya, Tokyo. (In Japanese.) Satake, Y., J. Ohwi, S. Kitamura, S. Watari & T. Tominari (1982b). Wild Flowers of Japan, Herbaceous plants III.  Heibonsya, Tokyo. (In Japanese.) Toyohara, G. (1984). A phytosociological study and a ten-tative draft on vegetation mapping of the secondary forests in Hiroshima Prefecture with special reference to pine forests.  J. Sci. Hiroshima Univ. Ser. B, Div. 2, 19: 131-170. 　Reference URLJapan Meteorological Agency, Weather statistics informa-tion. http://www.data.jma.go.jp/obd/stats/etrn/index.php

The vegetation on the granite rock area at Ashimori, Okayama City, S.W. Honshu, Japan

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オカヤマシ アシモリ ニオケル カコウガン チイキ ノ ショクセイ

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オカヤマシ アシモリ ニオケル カコウガン チイキ ノ ショクセイ

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オカヤマシアシモリニオケルカコウガンチイキノショクセイ