Phylogeny of the tropical tree family Dipterocarpaceae based on nucleotide sequences of the chloroplast RBCL gene

The Dipterocarpaceae, well-known trees of the Asian rain forests, have been variously assigned to Malvales and Theales. The family, if the Monotoideae of Africa (30 species) and South America and the Pakaraimoideae of South America (one species) are included, comprises over 500 species. Despite the high diversity and ecological dominance of the Dipterocarpaceae, phylogenetic relationships within the family as well as between dipterocarps and other angiosperm families remain poorly defined. We conducted parsimony analyses on rbcL sequences from 35 species to reconstruct the phylogeny of the Dipterocarpaceae. The consensus tree resulting from these analyses shows that the members of Dipterocarpaceae, including Monotes and Pakaraimaea, form a monophyletic group closely related to the family Sarcolaenaceae and are allied to Malvales. The present generic and higher taxon circumscriptions of Dipterocarpaceae are mostly in agreement with this molecular phylogeny with the exception of the genus Hopea, which forms a clade with Shorea sections Anthoshorea and Doona. Phylogenetic placement of Dipterocarpus and Dryobalanops remains unresolved. Further studies involving representative taxa from Cistaceae, Elaeocarpaceae, Hopea, Shorea, Dipterocarpus, and Dryobalanops will be necessary for a comprehensive understanding of the phylogeny and generic limits of the Dipterocarpaceae

The sub-basin springs of Poxim river, state of Sergipe: the degradation to restoration

Estudos ambientais em bacias hidrográficas são fundamentais para o entendimento do uso dos recursos naturais e dos problemas relacionados à ocupação do espaço. Em Sergipe, há necessidade de se obter informações para fins de planejamento e gestão futura de suas bacias hidrográficas, uma vez que gradualmente observa-se uma redução do volume produzido nos cursos d'água e da qualidade de suas águas, que são imprescindíveis para o abastecimento humano, a utilização na agricultura e na indústria. Devido ao acelerado processo de supressão da vegetação na sub-bacia hidrográfica do rio Poxim, formada pelos rios Poxim-mirim, Poxim-açu, e Pitanga e seus pequenos tributários, foi realizado um diagnóstico para se verificar o estado de conservação das suas principais nascentes, a situação quanto ao fluxo de água, as formas de uso e ocupação do solo no entorno destas e os tipos fisionômicos de vegetação remanescentes. As informações obtidas serão úteis para a realização de projetos de restauração ambiental, a promoção de melhorias no ambiente e nas comunidades rurais e resgate da diversidade da flora e fauna nestas áreas. Observou-se que as 20 principais nascentes dos rios e tributários que compõem a sub-bacia hidrográfica do rio Poxim, apresentam alterações decorrentes da acelerada antropização (90%), a maioria delas (65%) com elevada degradação (sem raio mínimo de 50m de vegetação) e ocupadas por agricultura (50%) e pastagens (35%). Somente duas nascentes encontram-se preservadas. Quanto à composição florística, as espécies identificadas (43) podem ser utilizadas em projetos futuros para restauração das nascentes e dos cursos d'água nesta sub-bacia hidrográfica. _________________________________________________________________________________________ ABSTRACT: Environmental studies on river basins are fundamental to understanding the natural resources use and the problems related to the space occupation. In Sergipe, it is necessary to obtain information for planning purposes and future management of their watersheds, once the watercourses volume and its quality are reducing gradually, which are essential for human supply and use in agriculture and industry. Due to the accelerated removal of vegetation in the river Poxim sub-basin, formed by the Poxim-Mirim, Poxim-Açu, Pitanga rivers, and its small tributaries, a diagnosis was carried out to verify the conservation status of their main sources, the situation on the water flow, the different uses, and land use around these sources and the remaining vegetation physiognomic types. The information is useful for carrying out environmental restoration projects, promoting improvements in the environment and in the rural communities and for the flora and fauna diversity rescue in these areas. It was observed that the 20 rivers sources top and tributaries that compose the river Poxim sub-basin showed changes from accelerated human anthropization (90%), most (65%) with high degradation (no vegetation in the minimum radius of 50 m), being occupied by agriculture (50%) and pastures (35%). Only two sources were preserved. The floristic composition, the identified species (43) can be used in future projects for sources and watercourses restoration in this sub-basin

Phytogéographie tropicale : réalités et perspectives

Distribution géographique, structures et fonctionnements actuels des plantes tropicales sont les résultats d'adaptations du passé face aux contraintes du milieu. Provoquées au cours des temps géologiques elles ont été influencées par les variations climatiques anciennes. Ces dernières décennies l'intensification de la pression anthropique sur les arbres de valeur est devenue l'agent prépondérant de la transformation des forêts tropicales. L'excès d'ouvertures de la voûte entraîne une hausse des températures ambiantes et un assèchement. Face aux conditions nouvelles, les adaptations du passé peuvent ne plus convenir. Pour enrayer les processus destructeurs il est parfois possible de modifier les comportements actuels de plantes. Cela implique que soient définis puis utilisés, leur plasticité biologique et les facteurs qui la contrôlent. Les adaptations naturelles du passé ont conduit aux formes variées de la diversité biologique actuelle. Les inductions expérimentales du présent concernent des transformations des espèces existantes. Elles peuvent aussi consister en une utilisation rationnelle d'espèces particulièrement plastiques hors de leur milieu d'origine. Utilisation des forêts, modifications des comportements biologiques et transplantations d'espèces résistantes vers des milieux fragilisés inclinent la phytogéographie tropicale vers l'analyse et la construction de "paysages anthropisés". Des exemples sont pris dans la famille des Diptérocarpacées, au niveau des organes reproducteurs pour illustrer les tendances qui ont conduit à la diversité biologique actuelle, les états actuels de la plasticité biologique, ses limites, ses modifications éventuelles, et son rôle dans le "paysage" phytogéographique tropical. Sont ainsi examinés les résistances du matériel régénératif (graines et jeunes plantules) à la température et à la dessiccation, la programmation naturelle du comportement des graines, les essais de modifications par induction expérimentale. (Résumé d'auteur