著者

橘 ヒサ子 伊藤 浩司

出版者

北海道大学

雑誌

環境科学 : 北海道大学大学院環境科学研究科紀要 (ISSN:03868788)

巻号頁・発行日

vol.4, no.1, pp.13-79, 1981-03-23

被引用文献数

2

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In the present paper, the authors dealt with syntaxonomy of mire vegetation, and the relationship between distribution of plant communities classified and habitat conditions in Yufutsu Mire, in Province of Iburi, Central Hokkaido. Yufutsu Mire, which is sometimes called "Yufutsu Genya" in Japanese, is situated at 42°40' NL and 141°45' EL, and extends about 8km in the N-S direction and 10 km in the E-W direction in its dimension. Topographically, most of the mire vegetation is found on a flooplain developed in the tributaries of the Abira and Yufutsu, and some is found on the flat bottom of valleys at Kashiwabara and Shizukawa plateaus. In landscape, the present mire is characterized by having several pools and ponds, some of which attains 2-4 m in the max. depth. Increasing human interferences such as the river improvement works, manufacturing industries, agricultural activities, land reclamation etc. have damaged the mire vegetation so drastically that most of the vegetation has been destroyed, deteriolated and modified considerably, and that the rest of the original vegetation is on the brink of ruin. The classification of plant communities was based upon the principle of the Sociation-Association system. Fifty-nine sociations (including consociations and facies) and five associations (including two new ones) are recognized. Plant communities classified are as follows ; A. Hhydrophytic communities : a. Submerged plant community-1. the Vallisneria asitica-Hydrilla vertillata soc., 2. the Potamogeton heterophyllus soc., 3. the Potamogeton heterophyllus-Schonoplectus tabernaemontani soc. and 4. the Polamogeton. praelongus-Typha latifolia fragmentary soc. ; b. Floating-leaf communities-5. the Trapetum japonicae Ito, et al. 1970, 6. the Nymphaea tetragona var. tetragona-Utricularia japonica soc. and 7. the Brasenia schreberi-Potamogeton heterophyllus soc. ; c. Emergedplant communities-8. the Nuphar japonicum-Utricularia japonica soc., 9. the Zizania latifolia-Potamogeton heterophyllus soc., 10. the Menyanthes trifoliata-Brasenia schreberi soc., 11. the Schoenoplectus tabernaemontani-Eleocharis kamtshatica soc., 12. the Schoenoplectus tabernaemontani-Equiseturn fluviatile*Hippuris vulgaris soc., 13. the Schoenoplectus tabernaemontani facies and 14. the Hyppuris vulgaris facies, 15. the Zizano-Phragmitetum Nakano, 1944. B. Marsh vegetation : 16. the Eleocharis kamtschatica-Hippuris vulgar is-Equisetum fluviatile soc., 17. the Eleocharis kamtschatica-Juncus papillosus soc., 18. the Eriocaulon deconflorum (・Eriocaulon monococcon)-Carex viridula soc. 19. the Eriocaulon monococcon-Juncus papillosus soc., 20. the Rhynchospora alba-Rhynchospora faberi soc., 21. the Eriophorum gracile-Carex limosa soc. C. Fen vegetation : 22. the Carex lyngbyei-Carex vesicaria soc., 23. the Carex lyngbyei-Calamagrostis langsdorffli soc., 24. the Carex -visicaria-Carex thunbergii soc., 25. the Carex thunbergii-Juncus papillosus soc., 26. the Carex thunbergii-Equisetum fluviatile soc., 27. the Carexkoidzumii-Eriophorum gracile soc., 28. the Carex koidzumii-Carex pseudocuraica soc., 29. the Myrico-Caricetum koidzumii (=the Myrico-Caricetum lariocarpae var. occultantis) Ko. Ito et Tachibana, assoc. nov. (1) the Carex koidzumii-Rhynchospora fauriei soc., (2) the Carex koidzumii consoc., (3) the Carex koidzumii-Calajnagrostis langsdorffii soc. and (4) the Carex koidzumii-Phragmites japonica soc. 30. the Lathyro-Calamagrostidetum langsdorffii Ko. Ito et Tachibana, assoc. nov. (1) the Calamagrostis langsdorffii-Carex lyngbyei soc., (2) the Calamagrostis langsdorffii-Lastrea thelypteris var. pubescens soc. and (3) the Calamagrostis langsdorffii consoc., 31. the Phragmites communis assoc. (1) the Phragmites communis-Carex lyngbyei soc., (2) the Phragmites communis-Carex thunbergii soc. (3) the Phragmites communis-Carex pseudocuraica soc. and (4) the Phragmites communis-Calamagrotis langsdorffii soc. D. Moss vegetation : 32. the Scirpus hudsonianus-Sphagnum imbricatum soc., 33. the Scirpus hudsonianus-Sphagnum palustre soc., 34. the Scirpus hudsonianus-Sphagnum subfulvum soc., 35. the Scirpus hudsonianus-Ledum palustre var. diversipilosum-Polytrichum juniperinum var. gracillius soc. and 36. the Hydrangea paniculata-Lastrea thelypteris var. pubescens-Sphagnum subfulvum soc. E. Alder vegetation : 37. the Alnus japonica var. arguta-Phragmites communis soc., 38. the Alnus japonica var. arguta-Calamagrostis langsdorffii soc., 39. the Alnus japonica var. arguta-Phragmites communis-Lastrea thelypteris var. pubescens soc., 40 the Alnus japonica var. arguta-Myrica gale var. tomentosa-Sphagnum subfulvum soc., 41. the Alnus japonica var. arguta-Myrica gale var. tomentosa-Lastrea thelypteris var. pubescens soc., 42. the Alnus japonica var. arguta-Spiraea salicifolia soc. and 43. the Alnus japonica var. arguta-Sasa apoiensis soc. F. Substitute vegetation : a. Thicket and Scrub-44. the Alnus japonica var. arguta-Hydrangea paniculata-Miscanthus sinensis-Lastrea thelypteris var. pubescens soc., 45. the Alnus japonica var. arguta*Hydrangea paniculata-Calamagrostis langsdorffii soc., 46. the Alnus japonica var. arguta-Hydrangea paniculata-Miscanthus sinensis-Polygonum ・weyrichii soc., 47. the Alnus japonica var. arguta-Polygonum rueyrichii soc., 48. the Myrica gale var. tomentosa-Ledum palustre var. diver-sipilosum soc. and 49. the Myrica gale var. tomentosa-Carex viridula soc. b. Herbaceous plant communities-50. the Calamagrostis langsdorffii-Lastrea thelypteris var. pubescens'Aster novi-belgii soc., 51. the Miscanthus sinetisis-Rubus parvifolius soc., 52. the Miscanthus sinensis-Polygonum weyrichii soc. and the Polygonum rveyrichii consoc. In this classification, two new associations are proposed ; the Myrico-Caricetum koidzumii (=the Myrico-Caricetum lasiocarpae var. occultantis) Ko. Ito et Tachibana and the Lathyro-Calamagrostidetum langsdorffii Ko. Ito et Tachibana. The former association is characterized by the predominance of Carex koidzumii and Myrica gale var. tomentosa and the frequent occurrence of some Sphagna and bog components. The latter is characterized by the predominance of Calamagrostis langsdorffii in association with Lathyrus palustris var. pilosus, and the frequent occurrence of Rubia jesoensis, Lysimachia thyrsiflora, Carex pseudocuraica, Lastrea thelypteris var. pubescens. The two associations mentioned above might be the typical communities developed in the boreal fen in Japan, and particularly distribute commonly in lowland mires of central and eastern parts of Hokkaido. The alder thicket occupies the margin of the mire which corresponds to "carr" vegetation of the British Isles. The components of the thicket are mainly Alnus japonica var. arguta, Phragmites communis, Calamagrostis langsdorffii, Spiraea salicifolia, Hydrangea paniculata, Myrica gale var. tomentosa and Lastrea thelypteris var. pubescens. The mire developed on floodplains is mostly occupied by various types of fen vegetation. The Phragmites communis assoc., Carex lyngbyei-C. vesicaria soc. and C. vesiceria-C. thunbergii soc. are found in the shallow depressions at the shores of ponds and rivers, which are frequently submerged in early spring, while the Lathyro-Calamagrostidetum langsdorffii is found on the convex and/or moderately sloping sites of the mire, which are saturated with water in soils. The Myrico-Caricetum koidzumii occurs usuallyarea between the alder thicket and the Lathyro-Calamagrostidetum langsdorffii. The characteristic marsh and Sphagnum communities are mainly found at Kashiwabara valley. In the center of the bottom of the valley, the Rhynchospora alba-R. faberi soc., the Eriocaulon decemflorum (・E. monococcon)-Carex viridula soc., the E. monococcon-Juncus papillosus soc. and the Eriophorum gracile-C. limosa soc. are established on thick muddy soils. Among them the first community occurs on the slightly convex sites on which mosses remain accumulate and are mingled with silts, the second and the third communities are on the depression and the fourth community is developed around the shores of ponds. Many Sphagnum hummocks distribute sporadically on the margins of the valley. The Scirpus hudsonianus-Sphagnum inibricatum soc. and the S. hudsonianus-Sph. palustre soc. occur on lower hummocks, and the S. hndsonianus-Sph. subfulvum soc. occurs on taller hummocks Moreover, the S. hudsonianus-Ledum palustre var. diversipilosum-polytrichum juniperinum var. gracillius soc. occurs on the summit of taller hummocks, and the Alnus japonica var. arguta-Myrica gale var. tomentosa-Sph. subfulvum soc. occurs on the summit of older and lower hummocks, which reflect the final stage of the Sphagnum hummocks in this mire vegetation. The distribution of plant communities classified is controlled by the micro-relief, the seasonal fluctuation of underground water level and the sedimentation of mud carried in flood. As a result of the eco-sociological analyses of the soil profiles and actual vegetation, it is proved that most of the Yufutsu mire vegetation was originated from eutrophic reed swamps at a starting point of the terrestrial vegetation, and that the valley mire of Kashiwabara plateau was originated from oligotrophic marshes which, had been developed on the impermeable volcanic ash accumulated on the flat bottom of valley.