{"created":"2021-03-01T06:13:30.413593+00:00","id":6877,"links":{},"metadata":{"_buckets":{"deposit":"689f86f5-b62b-4c16-86f7-eb4968c5fc28"},"_deposit":{"id":"6877","owners":[],"pid":{"revision_id":0,"type":"depid","value":"6877"},"status":"published"},"_oai":{"id":"oai:nagoya.repo.nii.ac.jp:00006877","sets":["643:835:836:837"]},"author_link":["18230","18231"],"item_1615768549627":{"attribute_name":"出版タイプ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_9_alternative_title_19":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"Effects of inhabitation of the common cormorant (Phalacrocorax carbo Kuroda) on forest ecosystems : a basic study for conservation and management of the habitat","subitem_alternative_title_language":"en"}]},"item_9_biblio_info_6":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1997-12","bibliographicIssueDateType":"Issued"},"bibliographicPageEnd":"119","bibliographicPageStart":"75","bibliographicVolumeNumber":"16","bibliographic_titles":[{"bibliographic_title":"名古屋大学森林科学研究","bibliographic_titleLang":"ja"}]}]},"item_9_description_4":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"カワウ(Phalacrocorax carbo Kuroda)は全長約80cmの大型の水鳥で、水辺の林に集団でコロニーを形成して繁殖する｡本種がコロニーを形成した森林では、カワウの活動による様々な影響を受けて樹木や付近の下層植生が衰弱･枯死するという現象がみられる。近年、本種の個体数増加に伴い新たにコロニーが形成され、コロニーにおける樹木の衰弱･枯死が問題とされるケースが各地で増加している。本研究では、カワウコロニーにおける普遍的な生態系保全･管理体系を構築していくために、カワウの生息地で起こる樹木の衰弱の機構や、コロニー形成による森林生態系への影響を明らかにすることを目的とし、野外調査と野外実験を併用した総合的な研究を行った。具体的な調査内容と結果は以下のとおりである｡(1)カワウ生息地における森林の変化1.1992年3月～11月にかけて、琵琶湖の2つのカワウコロニー(竹生島、伊崎)において、コロニーが形成された森林の状態を、その植物の種組成および空間構造に着目目して解析した｡2.カワウコロニー内の森林は、空間構造により3つのタイプ、すなわち高木層が閉鎖している(タイプ1)、高木層･草本層ともに被覆度が低い(タイプ2)、被覆度は高木層で低く,逆に草本層が閉鎖している(タイプ3)に類別できた｡3.カワウの営巣密度は、タイプ2の一部を除いた残りの地域では、ほとんど同じであった｡4.カワウが営巣木として利用しているサイズ(樹高と胸高直径)の大きな樹木では、とくにひどくダメージを受けて衰弱していた。また樹種では、スギやヒノキの衰弱の程度が落葉樹と常緑樹よりも大きかった。5.コロニーの林床では, 樹木の実生や幼樹はほとんど認められず、イタドリとヨウシュヤマゴボウなど数種の草本が優占していた｡(2) カワウの樹上活動が森林に与える影響1.1993年12月から1994年11月まで、知多半島鵜の山のカワウコロニーの内外でリターフォールの調査を行った結果、コロニー内では樹木の葉、枝、花、種子、果実、昆虫などの動物遺体のほかに、草本の葉や茎、魚類や甲殻類(エビ類･カニ類)、カワウの糞が回収された｡2.樹種構成が類似した調査区間で年間リター量との比較を行ったところ、葉の年間リター量はカワウの非生息地の方がカワウの生息地より、またカワウの営巣密度が低い地域の方が高い地域より、それぞれ多かった｡枝の年間リター量は、生息地と非生息地間の比較では葉のリター量と同様の傾向があったが, 営巣密度の違う地域間の比較では葉のリター量と逆の傾向があった。枝葉以外の年間リター量はカワウの糞の多少を反映し、生息地の方が非生息地より、営巣密度が高い地域の方が低い地域より多かった｡3.樹種構成が類似した調査区間でリターフォール量の季節変化を比較すると、葉と枝のリター量では、生息地と非生息地間および営巣密度の異なる地域間ともに、カワウの生息状況に起因すると考えられる相違は認められなかった｡4.カワウによる枝葉の折り取り量を反映すると考えられる葉(芽)つき枝のリター量は、生息地の方が非生息地より、営巣密度が高い地域の方が低い地域よりも多かった｡また、生息地および営巣密度が高い地域におけるこれらのリター量は、5～7月のカワウの育雛期および11月のカワウの集合期に多くなっていた｡(3) カワウの生息地における土壌の性質1.1992年の7月と8月に、琵琶湖の2つのカワウコロニーの内外で土壌断面を作成し、層位の測定を行った。また、深さ5cmから45cm まで10cm ごとに採集した5層の土壌サンプルを用いて、総窒素量、総炭素量、pH、含水比((含水量/乾重)×100(%))の測定を行った｡2. 2つのコロニーともに、コロニー内の土壌の方がコロニー外の土壌よりもA_0層が厚い傾向が認められた｡3.コロニー内の土壌中の総炭素量および総窒素量は、深さ5cmの表層部においてコロニー外の土壌よりも多い傾向が認められた｡4.少なくとも調査を行った深さ50cm までは、コロニー内の土壌pHはコロニー外の土壌pHより約0.5低い値を示した。5.土壌含水比は、コロニー内の深さ5cm と15cmの表層部でのみ、大きな値を示す傾向が認められた｡(4)カワウ生息地における樹木幼齢個体群の生育特性1.1995年の3月から9月にかけて、カワウコロニーの内外で、樹木種子(アカマツ、コナラ)を用いた発芽試験と、樹木実生(アカマツ、コナラ)および幼樹(コナラ)を用いた生存実験を行った。さらに、カワウの糞の付着状態別(葉と周辺の土壌への糞の付着の有無)に樹木実生(アラカシ)の生存実験も行った｡2.　3月から4月にかけて播種した種子の発芽率は、アカマツ、コナラともに、コロニー内の方がコロニー外より低かった｡種子の発芽率は、調査区付近の降糞量および土壌含水量と高い相関が認められたが、土壌pHおよび相対照度との相関は低かった｡発芽しなかった種子は、コロニー外の一部を除いてその大部分が土中で枯死していた｡3.発芽後のアカマツ実生は、コロニー外のものが徐々に枯死していったのに対し、コロニー内のものはほとんどすぐに消失した｡発芽後のコナラ実生も、コロニー外のものは9月下旬まで生存する個体があったのに対し、コロニー内のものはほとんどの個体が枯死した｡また、コロニー外のコナラ実生は、小動物に食害されて枯死する個体が多かったが、コロニー内のコナラ実生は、葉の周縁部に壊死が生じた後に枯死する個体が多かった｡4.コロニー内外に移植したコナラの幼樹では、コロニー内に移植したものの方が生存率が低かった｡また、コナラ実生の場合と同様に、コロニー内のコナラ幼樹には葉の周縁部に萎凋･壊死が、コロニー外のコナラ幼樹には食害による葉の損失が頻繁に確認された｡5.ポットに植栽したアラカシ実生を、糞が全くかからない処理区、糞が葉だけにかかる処理区、糞がポット内の土壌だけにかかる処理区、糞が葉とポット内の土壌の双方にかかる処理区に分けてコロニー周辺に配置したところ、糞が全くかからない処理区以外の3つの処理区では、大部分の実生が枯死した。(5) カワウの巣材集め行動が森林に与える影響1.1991年11月から1996年4月にかけて、知多半島鵜の山のカワウコロニーにおいて、カワウの造巣活動の観察、および巣と巣材の計測を行った｡2.カワウによる巣材採集は、毎年12月から5月にかけて観察された｡採集地点の大部分はコロニー内部かその周辺部にあり、コロニーの範囲から離れているものでも200m以内には収まっていた｡3.巣材の採集方法としては、樹上で樹木の枝葉を折り取る場合、地上で草本やササ等の地上性植物を折り取る場合、地上で落ちている植物片等を拾い取る場合の3パターンが確認された。4.つがいごとに巣材の採集行動を観察したところ、個々のつがいで樹上採集と地上採集の割合は異なっていた｡5.3つの地域で2年間にわたり採集された巣(計61巣)の重さは、地域間、年度間で有意な差は認められなかった｡これらの平均重量は、1.71kg d.wtであった｡巣の長径、短径、厚さは、それぞれ30～60cm、25～45cm、12～40cmであった｡これらの巣(計3巣)を解体したところ、いずれの巣でも重量比で70%以上が樹木の枝葉であった｡その他には、ササやセイタカアワダチソウなどの草本が認められた｡6.3つの地域の巣に運び込まれた巣材を調査したところ、樹木の枝葉とササ･草本を合わせた割合が90%以上を占めめていた｡両者の割合は地域ごとでそれぞれ、 造巣期の1～4月の間ほぼ一定の値を示した。また、生葉がついている巣材の割合は、どの地域でも40%前後であった。以上の結果を総合して、以下のことが示唆された｡1.カワウのコロニーが形成された森林では、植物の種組成や空間構造が単純化する｡このような森林の変化は、森林構造や種組成に影響を及ぼすことが知られている他の鳥類や嘱乳類の例(オオミズナギドリやニホンジカ)と比較して、速度が早く、しかも大きいと考えられた｡2.カワウのコロニーでは、カワウの羽ばたきや踏みつけなどの樹上活動の影響と考えられる樹木の枝葉の折り取りがあり、このような折り取りにより巣周辺では局所的に葉量が低下しているものと思われた｡折り取り量は、樹木側のフェノロジー、カワウのコロニーへの出入りの頻度およびカワウの個体密度に大きく関係しているものと推察された｡3.カワウのコロニーでは、大量の糞が林床に供給されるため、土壌の化学的、物理的性質が変化しており、とくに表層部ではその変化が顕著であることが示唆された。さらに、これらの土壌の変性は多くの植物に負の影響を与えることが示唆された｡また糞は、とまり木周辺の樹木や草本に付着するために、植物に直接的にも負の影響を与えることが示唆された｡4.カワウの巣材採集は、樹上および林床のいずれに対しても影響を及ぼすことが示唆された｡5.カワウによる樹木枝葉の折り取りへの反応は、植物のサイズや種類によって異なるために、衰弱･枯死に到るまでの早さも様々であることが示唆された。同様に、糞の付着や土壌の変性による負の影響も植物の種類によって異なることが示唆された｡6.カワウの活動による様々な影響を受けたコロニー内の森林では、まず高木層の葉量が低下し、つぎにそれ以下の草本層までの植物の衰弱が進み、さらには数種類の草本種のみが繁茂するという順序で変化していくことが推察された｡また、それに伴って、カワウの営巣数も変化すると推察された｡7.本研究の結果をカワウの生息地における樹木の衰弱･枯死問題への対応策に反映させるためのいくつかの提言を行った｡","subitem_description_language":"ja","subitem_description_type":"Abstract"},{"subitem_description":"The common cormorant (Phalacrocorax carbo Kuroda) is a large water-bird which breeds in colonies at waterside forests. Colonies and roosts of this species are often established in isolated forests such as islands or urban green tracts, and in such areas trees used for nesting and roosts have been declining because of the cormorants' various activities.In Japan there has been an increasing number of new colonics as a result of a recent increase in the number of cormorants and at some sites the decline or death of trees has become a serious problem in the conservation of forest environments. This study aimed to establish a practical system for conservation and management of forests colonized by avian populations which utilize trees as nests and roost in colonies. Some field surveys and experiments were performed to clarify the mechanisms of tree decline and the effects of cormorant colonization on the forest ecosystems. An outline of this study and major findings are summarized as follows. (1)Vegetational changes in forests colonized by the common cormorant 1.The species composition and structure of forest vegetation colonized by cormorants were surveyed from March to November 1992 in two colonies (Chikubu Island and Isaki Cape sites) at Lake Biwa, central Japan. 2.The status of vegetation in each colony was classified arbitrarily into three types according to the external appearance of tree,shrub and herb layers: dense tree layer (Type 1), sparse tree layer with sparse herb layer (Type 2) and sparse tree layer with dense herb layer (Type3). 3.Densities of cormorant nesting were mostly similar among the three types, except for part of Type2. 4.In particular, large trees on which the cormorants nested were heavily damaged, Chamaecyparis obtusa and Cryptomeria japonica being damaged more seriously  than other evergreen or deciduous species. 5.The forest floor of the colony had few seedlings and saplings of woody plants, whereas a few herbaceous species such as Reynoutria japonica and Phytolacca americana were dominant. (2)Effects of cormorant activities on trees in the forests 1.Litterfall accumulation was surveyed in some forest stands both inside and outside the colony from December 1993 to November 1994 at the Unoyama site on the Chita Peninsula, central Japan. Litterfall in the colony was derived from leaves and stems of herbaceous plants,various organs of woody plants, dead insect bodies, detritus of fish and crustaceans (prawns and crabs) from the cormorants' food and cormoralnt feces. 2.Comparison of plots with a similar species composition of woody plants showed that the annual leaf litterfall was larger outside than inside the cololy, and larger in nesting sites with low than high cormorant density. The annual litterfall of twigs and branches showed a tendency similar to leaf litterfall between inside and outside the colony, but comparison between the inside and the outside of the colony with different densities of cormorant nesting showed an inverse relationship to that for leaf litterfall. The annual litterfall of other items was larger inside than outside the colony, which was reflected in the supply of cormorant feces. 3.Comparison between plots with a similar species composition of woody plants also demonstrated that  there was no difference in the seasonal changes in leaf and twig litterfall, probably due to a difference in the status of the cormorant nesting habits inside and  outside the colony and between different nesting densities. 4.The litterfall of twigs with leaves, which seems to reflect the intensity of twig snapping by the cormorants, was larger inside than outside the colony, and larger at nesting sites with high cormorant density than at those with low density. The litterfall inside the colony and high-density nesting sites increased during the period from May to June, which corresponded to the brooding period, and in November when the number of cormorants increased. (3) Changes in soil propeties in the colonies 1.Some properties of the soil at l0-cm depth intervals down to 50 cm in colonies on Chikubu Island and Isaki Cape were compared with those outside the colonies in June and August 1992. 2.In both colonies the thickness of the A_o horizon tended to be greater inside than outside the colony. 3.At 5 cm depth, the mean total nitrogen and carbon contents in the colony tended to be higher than those   outside the colony. 4. Down to 50 cm depth, the soil pH was significantly lower (by ca pH 0.5) inside than outside the colony. 5. The moisture ratio tended to be higher inside than  outside the colony only in the depth range from 5 to15 cm. (4)Seed germination and seedling survival in the colony 1. Seed germination and seedling survival of some woody plants were examined experimentally inside  and outside the colony at Unoyama from March to September 1995. 2.Germination of both Quercus serrata and Pinus densiflora seeds sown during the period from March to April was less successful inside than outside the colony. The percentage of germination success was negatively correlated with the amount of cormorant feces scattered on the ground and also with the water content of the soil, but showed a less marked relationship with soil pH or light intensity on the forest floor. Seeds which did not germinate successfully mostly died under the ground except for a few seeds outside the colony. 3.Pinus densiflora seedlings in the colony died soon after germination, whereas those outside the colony gradually deteriorated. Most Q. serrata seedlings in the colony died of necrosis, whereas those on the outside survived until late September and then died of defoliation probably due to herbivorous insects. 4.The survival rate of Q. serrata saplings planted inside the colony was less than that of saplings planted on the outside. Similarly to the seedlings, saplings planted in the colony suffered necrosis on their foliage, while defoliation was recognized for those outside of the colony. 5.Quercus glauca seedlings planted in plastic pots were prepared for the following four treatments, and set in and around the colony: 1) exposure of both the leaves of a seedling and the soil in the pot to cormorarnt feces under natural conditions; 2) exposure of leaves to feces; 3) exposure of the soil to feces; 4) exposure of  both leaves and soil to no feces. Survival rates of the  seedlings with feces scattered on their leaves and/or  the soil in the pot were significantly lower than those  with no feces on the leaves or soil. \\n(5) Effects of nest-material collection by cormorants on the forest around the colony 1.Observations of nesting activities and measurements  of nests and nest materials were performed at the  Unoyama site from November 1991 to April 1996. 2.Nesting activities in this site were observed from  December to May in each year. The cormorants  collected nest-materials just inside and around the colony within a range of ca 200m. 3.There were three patterns of nest-material collection : snapping of twigs from trees, snapping stems of  herbaceous plants and bamboo grasses on the ground, and picking up plant tips from the ground. The ratio of frequencies for nest-material collection on trees to  those on the ground differed among cormorant pairs. 4. The mass of 61 nests collected in three particular areas in the colony did not differ significantly between  areas or between years. The average mass of the nests was 1.7 kg d.wt, and the major axis, minor axis and depth were 30-60, 25-45 and 12-40 cm, respectively. More than 70% of nest materials (by mass) consisted of twigs and leaves of woody plants, the other materials being bamboo grasses and herbaceous plants such as Solidago altissima. 5. More than 90% of nest materials brought to the cormorants' nests in the three areas consisted of twigs and leaves of woody plants, bamboos and herbaceous plants. The proportions were almost the same among months from January to April in each area. The proportion of nest materials containing fresh leaves accounted for ca 40% in all areas. The results yielded the following conclusions and suggestions: 1. ln forests colonized by the common cormorant,the species composition and structure of the vegetation are highly simplified due to the dominance of particular plant species adapted to forest environments altered by cormorants' inhabitation. The change appears to occur faster and more drastically than in other forests colonized by birds and mammals such as the  streaked shearwater (Calonectris leucomelas) and the sika deer (Cervus nippon). 2.In the cormorant colonies, the snapping of twigs and foliage which frcquently occurs is due mostly to flapping and trampling by the cormorants, and appears to cause a local reduction in the foliage of trees around the nests. Seasonal changes in the biomass of organs  broken off by the cormorants were strongly related to the phenology of the trees, to the frequency of movement in and out of their nests, and to nest density. 3. A large amount of cormorant feces dropped on the forest floor causes changes in the chemical and physical properties of the soil in the colonies, and such changes are most apparent in the surface and upper layers of the soil. This suggests that plants in the colonies would suffer various detrimental effects indirectly through changes in the soil environment. Cormorant feces would also have direct negative effects on plants around the roosts through their adhesion to the foliage. 4.The collection of nest material by the cormorants would cause disturbance to both individual trees and the forest floor. 5.The degree of tree decline was different among species, due probably to a difference in the response to loss of foliage snapped off by the cormorants. The response to negative effects through adhesion of feces to the foliage or changes in soil properties would also differ among species. 6. Forest vegetation affected by various activities of the cormorant is suggested to change according to the following sequence of processes:1) loss of foliage in  the tree layer:  2) decline of plants in other layers; 3) establishment of a highly simplified vegetation structure where only a few particular herbaceous plants predominate. In accordance with such vegetational succession, the number of cormorant nests is expected to change. 7.On the basis of the present results, some practical suggestions are proposed for the problem of decline in forests colonized by the common cormorant.","subitem_description_language":"en","subitem_description_type":"Abstract"}]},"item_9_description_5":{"attribute_name":"内容記述","attribute_value_mlt":[{"subitem_description":"農林水産研究情報センターで作成したPDFファイルを使用している。","subitem_description_language":"ja","subitem_description_type":"Other"}]},"item_9_identifier_60":{"attribute_name":"URI","attribute_value_mlt":[{"subitem_identifier_type":"HDL","subitem_identifier_uri":"http://hdl.handle.net/2237/8544"}]},"item_9_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.18999/nagufs.16.75","subitem_identifier_reg_type":"JaLC"}]},"item_9_publisher_32":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"名古屋大学農学部付属演習林","subitem_publisher_language":"ja"}]},"item_9_relation_43":{"attribute_name":"関連情報","attribute_value_mlt":[{"subitem_relation_type":"isVersionOf","subitem_relation_type_id":{"subitem_relation_type_id_text":"http://rms1.agsearch.agropedia.affrc.go.jp/contents/JASI/pdf/academy/57-2258.pdf","subitem_relation_type_select":"URI"}}]},"item_9_select_15":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_select_item":"publisher"}]},"item_9_source_id_7":{"attribute_name":"ISSN（print）","attribute_value_mlt":[{"subitem_source_identifier":"1344-2457","subitem_source_identifier_type":"PISSN"}]},"item_9_text_14":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_text_value":"application/pdf"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"石田, 朗","creatorNameLang":"ja"}],"nameIdentifiers":[{"nameIdentifier":"18230","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"ISHIDA, Akira","creatorNameLang":"en"}],"nameIdentifiers":[{"nameIdentifier":"18231","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2018-02-19"}],"displaytype":"detail","filename":"nagufs_16_75.pdf","filesize":[{"value":"11.4 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"nagufs_16_75.pdf","objectType":"fulltext","url":"https://nagoya.repo.nii.ac.jp/record/6877/files/nagufs_16_75.pdf"},"version_id":"2ffcb413-0112-45b4-93ec-95f89c345a71"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"カワウの生息が森林生態系に及ぼす影響 : カワウ生息地の維持・管理に向けての基礎的研究","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"カワウの生息が森林生態系に及ぼす影響 : カワウ生息地の維持・管理に向けての基礎的研究","subitem_title_language":"ja"}]},"item_type_id":"9","owner":"1","path":["837"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2007-07-17"},"publish_date":"2007-07-17","publish_status":"0","recid":"6877","relation_version_is_last":true,"title":["カワウの生息が森林生態系に及ぼす影響 : カワウ生息地の維持・管理に向けての基礎的研究"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-01-16T03:52:17.740428+00:00"}