{"created":"2021-03-01T06:22:18.944633+00:00","id":5614,"links":{},"metadata":{"_buckets":{"deposit":"8d4ae01d-0ab4-4ad4-bd1f-fd32b7a20d02"},"_deposit":{"id":"5614","owners":[],"pid":{"revision_id":0,"type":"depid","value":"5614"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00005614","sets":["27:28:370","9:233:280"]},"item_7_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"大型草食獣が植物の量と質の変化を介して植食性昆虫に与える影響の時間スケール依存性"}]},"item_7_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2012-03-22","bibliographicIssueDateType":"Issued"},"bibliographic_titles":[{}]}]},"item_7_date_granted_25":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2012-03-22"}]},"item_7_degree_grantor_23":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"University of Tokyo (東京大学)"}]}]},"item_7_degree_name_20":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士(農学)"}]},"item_7_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Species interact with each other both directly and indirectly, and indirect effects have similar or even stronger impacts on population dynamics and community structure than direct effect. Indirect effects were divided into two main processes based on the mode of transmitter response; density-mediated indirect effects (DMIEs) and trait-mediated indirect effects (TMIEs). To predict the indirect interactions caused by multiple processes, researchers need to detect the factor affecting the relative strength of these processes. Because there are differences in response speeds between trait changes via phenotypic plasticity at the individual level and demographic changes at the population level, the relative importance of these effects is expected to show time-scale dependency. However, no empirical study provided evidence supporting time-scale dependency of relative strength of DMIEs and TMIEs. The purpose of this study is to demonstrate the time-scale dependency in density- and trait-mediated indirect effects in \"large herbivore-plant-phytophagous insects\" systems, in which plant quantity- and quality-mediated interactions were widely known. First, I explore general patterns in the direction of indirect effects of large herbivores on insect densities. Second, I examined indirect interactions between sika deer (Cervus nippon)-woody pipevine (Aristolochia kaempferi)-swallowtail butterfly (Byasa alcinous) in the Boso Peninsula, and estimated the time-scale dependency of plant quantity- and quality-mediated effects. Chapter 2 explores general patterns in the directions of indirect effects of large herbivores on insect densities. Large herbivores affect insect abundance both positively and negatively, or did not show significant impacts. The directions of total effects are determined by the relative strength of the positive and negative effects, which is assumed to associate with plant qualitative and quantitative changes induced by browsing. I focused on three factors associated with the appearance of density-mediated indirect effects, i.e., plant life-form, measures of insect density, and time-scale of study. As a result, differences in these factors affected the direction of indirect effects. Studies mediated by forb or grass exhibited negative effects on insect abundance in long-term studies, whereas studies mediated by trees tended to show positive effects on attack rates by insects in short-term studies. Consideration of the above three factors may help predict the occurrence of negative effects in nature. Chapter 3 investigated the processes of trait-mediated indirect effects in the \"sika deer -- woody pipevine -- swallowtail butterfly\" system. First, to assess how A. kaempferi responds to deer browsing, I conducted field experiments using deer exclosures. Outside the exclosures, deer browsing stimulated the regrowth of A. kaempferi. Simulated browsing also induced compensatory growth of A. kaempferi and improved leaf nutritional and physical qualities for insects. Second, to examine the young leaf utilization by B. alcinous in response to increasing deer densities, I conducted field survey on the availability and utilization patterns of young leaves across deer-density gradient. Young leaf availability increased with deer density, and young leaf utilization by butterflies also increased. Third, to examine the effects of plant trait-change on larval and pupal performance of B. alcinous, I conducted laboratory experiments raring larvae at different food-quality treatments. Byasa alcinous larvae fed by good quality leaves increased their survival rate, growth rate, and decreased the incidence of pupal diapause. Consequently, the combination between plastic response of A. kaempferi to deer browsing and plastic response of B. alcinous to food quality may lead to positive trait-mediated effects. Chapter 4 evaluated the effect of deer on the density of B. alcinous mediated by the changes in quantity and quality of A. kaempferi. The density of sika deer population in the Boso Peninsula was estimated for 15 years, and areas with different browsing histories are available. I conducted the field survey for A. kaempferi, and estimated the carry-over rate of responses of plant quantity and quality by the relationship between plant response and temporal trends in deer density. Leaf density of A. kaempferi exhibited high carry-over rate of the effect of deer browsing and cumulatively decreased in response to successive deer herbivory, while percentage of young leaves increased with current deer density. The high density of B. alcinous were observed in areas with high leaf density and high percentage of young leaves. Total estimated indirect effects showed a positive trend in short-term due to relatively strong quality-mediated effect, but they showed no specific trends in long-term because quality- and quantity- mediated effects canceled each other. According to these results, I found that the indirect effects of large herbivores on insects mediated by host plants exhibit a time-scale dependency. This study provides the first empirical evidence supporting the time-scale dependency of the relative importance of density- and trait-mediated effects. In large herbivore-plant insects system, the transmitter plants show slow and cumulative responses, which may cause time-scale dependency. In trophic cascade studies, transmitter species often have a short generational time and sometimes the recruitment to the local population in the following year is limited by large spatial-scale processes. In such cases, cumulative responses over years are unlikely to appear in small spatial scale experiments. In nature, inducer populations can show both fast- and slow-time scale dynamics, which may cause the rapid trait changes and the cumulative density changes in transmitter. To understand indirect interactions under the transient conditions, researchers should be in mind the existence of time-scale dependency.","subitem_description_type":"Abstract"}]},"item_7_dissertation_number_26":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第28109号"}]},"item_7_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"11686","nameIdentifierScheme":"WEKO"}],"names":[{"name":"髙木, 俊"}]}]},"item_7_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/00005605","subitem_identifier_reg_type":"JaLC"}]},"item_7_select_21":{"attribute_name":"学位","attribute_value_mlt":[{"subitem_select_item":"doctoral"}]},"item_7_subject_13":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"486","subitem_subject_scheme":"NDC"}]},"item_7_text_22":{"attribute_name":"学位分野","attribute_value_mlt":[{"subitem_text_value":"Agriculture (農学)"}]},"item_7_text_24":{"attribute_name":"研究科・専攻","attribute_value_mlt":[{"subitem_text_value":"Department of Ecosystem Studies, Graduate School of Agricultural and Life Sciences (農学生命科学研究科生圏システム学専攻)"}]},"item_7_text_27":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_text_value":"博農第3825号"}]},"item_7_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"東京大学大学院農学生命科学研究科生圏システム学専攻"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Takagi, Shun"}],"nameIdentifiers":[{"nameIdentifier":"11685","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":"2017-06-01"}],"displaytype":"detail","filename":"39-097117.pdf","filesize":[{"value":"7.5 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"39-097117.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/5614/files/39-097117.pdf"},"version_id":"6ca61d80-6570-435b-8a32-fac691454648"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Time-scale dependency of plant biomass- and trait-mediated indirect effects of large herbivores on phytophagous insects","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Time-scale dependency of plant biomass- and trait-mediated indirect effects of large herbivores on phytophagous insects"}]},"item_type_id":"7","owner":"1","path":["280","370"],"pubdate":{"attribute_name":"公開日","attribute_value":"2014-02-24"},"publish_date":"2014-02-24","publish_status":"0","recid":"5614","relation_version_is_last":true,"title":["Time-scale dependency of plant biomass- and trait-mediated indirect effects of large herbivores on phytophagous insects"],"weko_creator_id":"1","weko_shared_id":null},"updated":"2022-12-19T03:47:11.470312+00:00"}