{"created":"2022-01-27T02:39:15.521985+00:00","id":2002802,"links":{},"metadata":{"_buckets":{"deposit":"db9c6b1b-0de8-42ef-973e-b8c02c8c325c"},"_deposit":{"id":"2002802","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"2002802"},"status":"published"},"_oai":{"id":"oai:u-ryukyu.repo.nii.ac.jp:02002802","sets":["1642837622505:1642837905044:1642837918880","1642838403551:1642838407312"]},"author_link":[],"item_1617186331708":{"attribute_name":"Title","attribute_value_mlt":[{"subitem_title":"西表島樹林地における開墾放置土壌の理化学性変化(生産環境学科)","subitem_title_language":"ja"},{"subitem_title":"Changes in Physical and Chemical Properties of the Soil Abandoned after Clearing Forest (Department of Enviromental Sciences and Technology)","subitem_title_language":"en"}]},"item_1617186419668":{"attribute_name":"Creator","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"大屋, 一弘","creatorNameLang":"ja"}]},{"creatorNames":[{"creatorName":"比嘉, 基晶","creatorNameLang":"ja"}]},{"creatorNames":[{"creatorName":"渡嘉敷, 義浩","creatorNameLang":"ja"}]},{"creatorNames":[{"creatorName":"志茂, 守孝","creatorNameLang":"ja"}]},{"creatorNames":[{"creatorName":"Oya, Kazuhiro","creatorNameLang":"en"}]},{"creatorNames":[{"creatorName":"Higa, Motoaki","creatorNameLang":"en"}]},{"creatorNames":[{"creatorName":"Tokashiki, Yoshihiro","creatorNameLang":"en"}]},{"creatorNames":[{"creatorName":"Shimo, Moritaka","creatorNameLang":"en"}]}]},"item_1617186476635":{"attribute_name":"Access Rights","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_1617186609386":{"attribute_name":"Subject","attribute_value_mlt":[{"subitem_subject":"西表島","subitem_subject_language":"ja","subitem_subject_scheme":"Other"},{"subitem_subject":"開墾放置土壌","subitem_subject_language":"ja","subitem_subject_scheme":"Other"},{"subitem_subject":"土壌理化学性","subitem_subject_language":"ja","subitem_subject_scheme":"Other"},{"subitem_subject":"Iriomote Island","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"soils after clearing forest","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"physical and chemical properties of soil","subitem_subject_language":"en","subitem_subject_scheme":"Other"}]},"item_1617186626617":{"attribute_name":"Description","attribute_value_mlt":[{"subitem_description":"西表島の琉球大学熱帯農学研究施設内において, 1976年に樹林地を開墾してA区(林地), DG区(レーキドーザ開墾, 牧草植付後放置), DN区(レーキドーザ開墾, そのまま裸地放置), EG区(ブルドーザ開墾, 牧草植付後放置), EN区(ブルドーザ開墾, そのまま裸地放置)などの試験区を設け, 土壌の理化学性を経年的に調べ, 樹林地開墾という人為作用が土壌と周辺環境に及ぼす影響と, 環境の保全について論じた。土壌は酸性赤色系の砂壌土&acd;砂質埴壌土であった。開墾に伴う影響は土壌流亡(流失)による周辺環境の悪化や土壌そのものも肥沃度低下などが考えられるが, 土壌流亡に係わる土壌因子の透水性や受食性についてみると次の通りであった。透水性はレーキドーザやブルドーザで開墾すると, 極端に悪くなり, 2年後から徐々に回復する傾向がみられた。また, 粘土比や分散率によると, 開墾試験区土壌は勿論, 林地土壌も受食性の高い土壌であった。林地では受食性が高いにも拘らず土壌が植被による保護と高い透水性により流亡が抑えられ, 環境保全に役立っているが, 開墾地では透水性の低下が土壌流亡の大きな要因になると推定された。特に開墾直後においては透水性が著しく低下するので, 土壌流亡による環境への悪影響防止には, 開墾直後におけるマルチ或は草生による土壌被覆が極めて重要な対策と考えられる。土壌保全においてマルチの及ぼす効果は極めて大きいことが知られている^<7)>。土壌肥沃度の主要因をなす土壌化学性(pH, CEC, 窒素, 腐植, 交換性塩基)は, 林地下の土壌でも余り良い方ではなかったが, 開墾によりそれの不良化が認められた。しかし不良化の程度はブルドーザ開墾区(EG, EN)よりレーキドーザ開墾区(DG, DN)の方が軽かった。土壌化学性のうちで, 特に土壌炭素(腐植)含量の経年的な変化が試験区により異なることが認められた。すなわち, 土壌の炭素含有率はブルドーザ開墾区で極端(林地の22%)に低下し, その後の植生侵入が少なく, 16年経過しても林地の26%(EGとENの平均)しか回復しなかったが, レーキドーザによる開墾では林地の49%への低下があったものの, 植生の侵入が早く, 16年目には林地の63%(DGとDNの平均)に回復した。以上により, 当該調査地における開墾地土壌の保全には開墾直後における土壌被覆が重要な対策であり, 肥沃度保持にはブルドーザ開墾よりレーキドーザ開墾の方が好ましい手法と考えられた。また, 開墾地で森林回復を図るには16年以上の時間が必要であると考えられた。","subitem_description_type":"Other"},{"subitem_description":"Changes in physical and chemical properties of soil were investigated to estimate impact of human activities such as forest clearing on the measures of soil conservation and fertility, having 5 plots, about 0.1 ha each, in the forest of the Tropical Agriculture Research Institute on Iriomote Island. These plots included A (forest as control), DG (cleared by rakedoser, planted to grass for 3 years then abandoned), DN (cleared by rakedoser and kept naked), EG (cleared by bulldozer, planted to grass for 3 years then abandoned), and EN (cleared by bulldozer and kept naked), starting in 1976. The soil, derived from sandstones, reddish, and sandy loam to sandy clay loam, were sampled from the depth of 0 to 15cm, 3 from each plots, in 1976,1979 and 1991 and analyzed for physical and chemical properties. Water intake rate determined in the field was found to become very much depressed as cleared by the rakedoser and bulldozer and tended to recover a little 2 years later. The soil of all plots were judged as very erodible from clay ratio and dispersion rate. From these it was deemed that the soil is easily exposed to the danger of erosion because of its poor water intake rate coupled with high erodibility after clearing. Chemical properties such as pH, CEC, and contents of nitrogen, humus and exchangeable bases that have close relations to soil fertility were found to become inferior to the A plot soil after clearing, but the degree was slight in the soil of DG and DN plots. Percent of carbon in the soil, that is related to humus content, was higher in the DG and DN plots where more shrub invasion was observed, but it was only 63% of the A plot. From the above it was concluded that soil conservation measures are very important right after clearing forest, clearing by rakedoser is preferred to that by bulldozer in terms of soil fertility, and the recovery of humus content in the cleared soil to the level of forest requires more than 16 years in the investigated area.","subitem_description_type":"Other"},{"subitem_description":"紀要論文","subitem_description_type":"Other"}]},"item_1617186643794":{"attribute_name":"Publisher","attribute_value_mlt":[{"subitem_publisher":"琉球大学農学部","subitem_publisher_language":"ja"}]},"item_1617186702042":{"attribute_name":"Language","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_1617186783814":{"attribute_name":"Identifier","attribute_value_mlt":[{"subitem_identifier_type":"HDL","subitem_identifier_uri":"http://hdl.handle.net/20.500.12000/3773"}]},"item_1617186920753":{"attribute_name":"Source Identifier","attribute_value_mlt":[{"subitem_source_identifier":"0370-4246","subitem_source_identifier_type":"ISSN"},{"subitem_source_identifier":"AN00250548","subitem_source_identifier_type":"NCID"}]},"item_1617186941041":{"attribute_name":"Source Title","attribute_value_mlt":[{"subitem_source_title":"琉球大学農学部学術報告","subitem_source_title_language":"ja"},{"subitem_source_title":"The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus","subitem_source_title_language":"en"}]},"item_1617187056579":{"attribute_name":"Bibliographic Information","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1994-12-01","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"41","bibliographicPageEnd":"267","bibliographicPageStart":"257"}]},"item_1617258105262":{"attribute_name":"Resource Type","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_1617265215918":{"attribute_name":"Version Type","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_1617605131499":{"attribute_name":"File","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_access","filename":"KJ00000161753.pdf","mimetype":"application/pdf","url":{"objectType":"fulltext","url":"https://u-ryukyu.repo.nii.ac.jp/record/2002802/files/KJ00000161753.pdf"},"version_id":"87cd50a6-ef62-45a3-98b6-2a0ae63d00ff"}]},"item_title":"西表島樹林地における開墾放置土壌の理化学性変化(生産環境学科)","item_type_id":"15","owner":"1","path":["1642837918880","1642838407312"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-02-14"},"publish_date":"2008-02-14","publish_status":"0","recid":"2002802","relation_version_is_last":true,"title":["西表島樹林地における開墾放置土壌の理化学性変化(生産環境学科)"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-10-31T01:09:15.445706+00:00"}