No.130 研究課題 / Project
多摩川下流域における神社の境内の樹木の研究－特に境内の樹種構成とその配置についてStudy of the trees in the grounds of the shrines along the lower reaches of the Tama River.With emphasis on the kinds and distribution of the trees.| 一般研究 General Research |
No.130 |
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| 代表研究者 Principal Investigator |
秋山 好則 Yoshinori Akiyama |
| 所属（採択当時） Affiliation |
東京都立武蔵高校教諭 Teacher, Tokyo Metropolitan Musashi High School |
| 研究内容要約 Research Summary |
世田谷区内で５７社、大田区内で９４社の計１５１社の境内の樹木について調査を行った。 調査方法は境内を訪れて、神社名、位置している地形、拝殿・本殿などの建物を中心にして樹木の配置を調べた。対象とした樹木はＤＢＨ１０ｃｍ以上のすべての個体で、境内における位置と樹種名、さらにＤＢＨを実測あるいは目測で調べて記入した。 大木で注連が張られている場合は神社開係者に確認し、御神木を特定した。御神木については樹高も測定した。可能な限り、神社関係者にたいする聞き取り調査を行った。聞き取りの内容は、御神木の有無、その由来、昔の境内の樹木の様子、大木が枯れた場合はその時期と枯死原囚を教えてもらった。さらに樹木の育成・管理方法や氏子や官司さんたちの境内の樹木に対する想いなどについてもいろいろと教えてもらった。また、樹木を残していく上での間題点や障害になっている点なども話題になった。 結果 御神木について見ると、イチョウ、クロマツ、ケヤキ、スダジイ、サワラ、カヤ、ホウノキ、クスノキ、タブノキの９種類であり、イチョウが最も多かった。御神木が境内に在した神社は世田谷区内で２８％、大田区内で８．５％、あわせて１６％にすぎない。前回調査の多摩川中流域の場合は１８８社中７３社にあり、全体で３９％であったので、下流域においては境内に御神木と呼べるような大木（ＤＢＨ５０～１００ｃｍ）・木（ＤＢＨｌ００ｃｍ以上）が少ないと考えられる。 大木の分布を見ると、世田谷区内では２７種類で多い順に並べるとケヤキ、イチョウ、クロマツ、スダジイ、サワラ、イヌシデ、クスノキ、シラカシとなる。大田区内では１９種類でイチョウ、ケヤキ、スダジイ、サクラ、クロマツ、クスノキ、アカガシの順になる。 イチョウがどこでも多いのが特徴になっている。戦災にあっても焼け残ったり、戦後すぐに植えられて、大気汚染にも強いので良く成長し、都内の神社では量的に最も多い樹種となっている。 世田谷区内では大きな境内をもつ神社が多く、戦災の影響もあまりなく、他種類の樹木が良く生育し、鎮守の森が残されている場合が多い、一方大田区の場合は武蔵野台地上、段丘崖斜面上に位置している神社の境内では、大木が割合残されているが、低地の平坦地にある場合は戦災による消失や戦後の京浜地区の大気汚染の影響が大きく、樹木の生長が悪く、大木まで育っていない場合が多く見られる。世田谷・大田区以外の２３区域についても調査を進めているが。よく似た傾向を示している。今後データを充実させ、分析していきたいと考えている。 We studied trees growing at a total of 151 shrines: 57 in Setagaya Ward and 94 in Ota Ward. The following information was gathered: the names of the shrines; the topography of the areas where shrines were located; and the arrangement of the trees around structures, such as halls of worships and main inner shrines. Trees with DBH 3 10 cm were all studied: the location and the names of trees in shrines were examined, and DBH was measured visually or with measuring tools. When we found a tree with a sacred straw festoon, we confirmed whether it was a sacred tree, by asking shrine priests or workers about it. Height was also measured for sacred trees. We questioned as many shrine priests and workers as possible about the presence or absence of a sacred tree, its origin, past condition of trees around shrines, and when and why huge trees had died. Shrine parishioners and priests told us how to nurse and manage trees, as well as about their special feelings for trees. We also discussed with them the difficulties in maintaining trees from generation to generation. Results Nine types of trees were regarded as sacred: Ginkgo biloba, Pinus thunbergii [Japanese black pine], Zelkova serrata, Castanopsis cuspidata, Chamaecyparis pisifera [Japanese false cypress], Torreya nucifera, Magnolia obovata [Whiteleaf Japanese Magnolia], Cinnamomum camphora [camphor tree] and Machilus thunbergii. Among them, Ginkgo biloba was most commonly considered to be sacred. Sacred trees were observed only in 16% of all shrines: 28% in Setagaya Ward and 8.5% in Ota Ward. In the previous study in which we investigated 188 shrines in the middle Tama River basin , sacred trees were observed in 73 shrines, representing 39%. Therefore, it is suggested that, in the lower Tama River basin , there are only a few huge trees (DBH 50-100 cm) or trees (DBH 3 100 cm) that are large enough to be regarded as sacred. In Setagaya Ward, 27 types of huge trees were observed: Zelkova serrata, Ginkgo biloba, Pinus thunbergii, Castanopsis cuspidata, Chamaecyparis pisifera, Carpinus tschonoskii [Korean Hornbeam], Cinnamomum camphora and Quercus myrsinaefolia [Japanese white oak] (put in order with the most frequent at the top). In Ota Ward, 19 types of huge trees were observed: Ginkgo biloba, Zelkova serrata, Quercus myrsinaefolia, Prunus spp [cherry], Pinus thunbergii, Cinnamomum camphora and Quercus acuta [red oak] (in order of frequency, starting with the most frequent). It was interesting that Ginkgo biloba trees were commonly found at every shrine in Tokyo . This is because Ginkgo biloba trees escaped fire even during war, because they were planted as soon as the war was over, and because they are tolerant of air pollution. In Setagaya Ward, there are a number of shrines with a sacred precinct, most of which were not damaged during the war. In these shrines often there remain sacred groves with a wide variety of trees. As for Ota Ward, huge trees remain in the sacred precinct of shrines on Musashino Plateau or on cliffs and slopes of Musashino Terrace. At most shrines in the lowlands, however, trees were destroyed during the war, or are not able to grow large enough due to severe air pollution in Tokyo and Yokohama . Our ongoing research in other wards also show similar results. For the meantime, we would like to collect more data for further analysis. |
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