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付記する学位プログラム名: グローバル生存学大学院連携プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(地域研究) / 甲第21199号 / 地博第228号 / 新制||地||84(附属図書館) / 京都大学大学院アジア・アフリカ地域研究研究科東南アジア地域研究専攻 / (主査)教授 竹田 晋也, 教授 岩田 明久, 准教授 古澤 拓郎, 准教授 小坂 康之 / 学位規則第4条第1項該当 / Doctor of Area Studies / Kyoto University / DGAM

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Although the majority of species in the deciduous forests lose their leaves during the dry season, some of them present alternative strategies, such as the leaf movement position (from horizontal to vertical ) in order to reduce transpiration. This study describes the leaf anatomy of nine plant species that reduce water loss during the dry season using the strategy of leaf movement rather than leaf abscission. The studied species were Piper aduncum sp. L. (Piperaceae), Acalypha Müll gracilis. Arg. (Euphorbiaceae), Casearia sylvestris Sw (Salicaceae), Bauhinia L. ungulata (Fabaceae: Caesalpinoideae) Calyptranthes widgreniana Berg. (Myrtaceae), Trichilia elegans A. Juss (Meliaceae) Guarea guidonia (L.) Sleumer (Meliaceae), Myrsine umbellata Mart. (Myrsinaceae) e Psychotria carthagenensis Jacq. (Rubiaceae), from the Parque Estadual do Pau Furado (Triângulo Mineiro), Brazil. Samples of the leaf blades and petioles were processed according to the usual techniques for plant anatomy. No general anatomical petiole pattern was found. However, some characteristics are common to all species: (a) supporting tissue, usually represented by collenchyma; (b) large cortical cells with thin walls and small intercellular spaces and (c) reduction or absence of lignified fibers. All these features could enhance the petiole flexibility allowing leaf changing position. The leaf blade anatomy revealed structural traits that promote water savings, as well as efficient mechanisms against predation by herbivores. These important features can effectively contribute to the maintenance and existence of these species in deciduous forests. / Embora a maioria das espécies ocorrentes nas florestas estacionais deciduais perca suas folhas durante a estação seca, algumas delas apresentam estratégias alternativas, tais como, a mudança no posicionamento das folhas de horizontal para vertical, para reduzir a transpiração. Este estudo descreve a anatomia foliar de nove dessas espécies de planta que reduzem a perda de água, durante a estação seca, usando a estratégia do movimento foliar e não a de apresentarem abscisão foliar. As espécies estudadas foram Piper aduncum sp. L. (Piperaceae), Acalypha gracilis Müll. Arg. (Euphorbiaceae), Casearia sylvestris Sw. (Salicaceae), Bauhinia ungulata L. (Fabaceae: Caesalpinoideae), Calyptranthes widgreniana Berg. (Myrtaceae), Trichilia elegans A. Juss (Meliaceae), Guarea guidonia (L.) Sleumer (Meliaceae), Myrsine umbellata Mart. (Myrsinaceae) e Psychotria carthagenensis Jacq. (Rubiaceae) do Parque Estadual do Pau Furado (Triângulo Mineiro). As amostras do limbo e do pecíolo foram processadas de acordo com as técnicas usuais para anatomia vegetal. Nenhum padrão anatômico geral foi encontrado para o pecíolo nas espécies analisadas. No entanto, foram observadas algumas características anatômicas comuns a todas elas, como: (a) tecido de sustentação, geralmente, representado pelo colênquima, (b) células corticais grandes, de paredes delgadas e com pequenos espaços intercelulares e (c) redução ou ausência de fibras lignificadas. Todas essas características poderiam garantir a flexibilidade ao pecíolo e assim, permitir a mudança de posição das folhas. A anatomia do limbo revelou características estruturais que favorecem a economia de água, além de mecanismos eficientes contra a herbivoria, características estas importantes e que poderiam contribuir efetivamente para a manutenção e existência dessas espécies nas florestas estacionais deciduais. / Mestre em Ecologia e Conservação de Recursos Naturais

In this thesis, I examine the variation in plant species richness along gradients of productivity and disturbance in grasslands and forest habitats in southern Sweden, and I compare the documented patterns with theoretical predictions. Moreover, I evaluate the relative importance of habitat quality and habitat configuration for the occurrence of field layer species in deciduous forests. Finally, I present a new method for the determination of the regional species pool. To examine regional and local variation in plant species richness, I gathered data on species composition in plots of different size (0.001 - 1000 m2) in three vegetation types (deciduous forests, dry grasslands and coastal meadows) in four regions of southern Sweden (Öland, Gotland, Småland and Uppland). As predicted by the species pool hypothesis, differences in small-scale species richness of deciduous forests and dry grasslands were correlated with differences in the size of the regional species pool. Moreover, among plots large-scale diversity was predictive of small-scale diversity. Species diversity showed a hump-shaped relationship with productivity in forests, and was related to environmental heterogeneity and the size of the 'habitat-specific' species pool. In the two types of grassland examined, grazed sites were richer in species than abandoned sites. Moreover, both species composition and the representation of plants with different life-history characteristics differed between grazed and abandoned sites. As predicted by the intermediate disturbance hypothesis, species richness was highest at intermediate levels of grazing in coastal meadows. However, all the above patterns were scale-dependent, and not observed at all plot sizes. The occurrence of field layer species in deciduous forests was more strongly related to habitat quality (mainly soil factors) than to habitat configuration (forest area and isolation). Across species, low seed production, clonal reproduction and habitat specificity were negatively associated with isolation.

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