Composição e estrutura do componente arbóreo/arbustivo da floresta ciliar do arroio da Brigadeira, no Parque Municipal Fazenda Guajuviras, Canoas/RS

As florestas ciliares são formações vegetais extremamente importantes em termos ecológicos, principalmente para a manutenção da qualidade dos cursos d’água. Porém, apesar de serem protegidas por lei, elas vêm sendo erradicadas, principalmente em áreas urbanas. Desta forma, estudos detalhados sobre a composição florística e a ecologia dos remanescentes dessas florestas são fundamentais para embasar qualquer iniciativa de proteger e restaurar essas formações vegetais. Com o objetivo de avaliar a estrutura, o estado de preservação da floresta ciliar e fornecer subsídios para as adequadas ações de manejo na restauração dessa formação, foi realizado um levantamento florístico e fitossociológico da vegetação arbóreo/arbustiva do Arroio da Brigadeira na cidade de Canoas/RS, numa área remanescente dentro do Parque Municipal Fazenda Guajuviras. Para a caracterização da composição do estrato arbóreo dominante da floresta e categorias sucessionais, a vegetação lenhosa foi separada em três componentes: regenerante (0,20m ≤ h < 1m); arbóreo-arbustivo (1m ≥ h e DAP < 5cm); arbóreo (DAP ≥ 5cm). O delineamento amostral foi de 20 parcelas para todos os componentes, sendo as dimensões de 4m², 25m² e de 100m² para cada parcela, respectivamente para o primeiro, segundo e terceiro componente. A estrutura da vegetação foi verificada através da distribuição horizontal e vertical dos seus indivíduos. A estimativa da regeneração natural baseou-se nos valores relativos de freqüência e densidade de cada espécie em três classes de altura. A organização das comunidades vegetais foi analisada por análise de agrupamentos através do programa MULVA 5. Na composição florística encontraram-se 56 espécies distribuídas em 27 famílias botânicas. As espécies com maiores valores de regeneração natural total (RNT), responsáveis por mais de 50%, foram: Myrcia multiflora (Lam.) DC. (22,03%), Eugenia hyemalis Cambess. (14,04%), Daphnopsis racemosa Griseb. (10,60%) e Ocotea pulchella Mart. (10,16%). O alto potencial de regeneração natural, com abundância de espécies típicas de sub-bosque, ressalta a importância do estudo dos componentes dos estratos inferiores da floresta para o conhecimento da dinâmica florestal. No componente arbóreo constatou-se a densidade total por área (DTA) de 2120 ± 617 indivíduos.ha-1. O Índice de Diversidade de Shannon foi de 2,80. O DAP médio foi de 10,45 ± 5,65cm. As espécies com maior valor de importância (VI) foram Eugenia hyemalis Cambess. (44,09), Prunus myrtifolia Urb. (34,51), Myrsine coriacea (Sw.) R.Br. (30,12) e Mimosa bimucronata (DC.) Kuntze (29,68). Os exemplares mortos apresentaram alta DTA, 280 ± 204,17 indivíduos.ha-1, possivelmente em decorrência da competição por espaço a ser ocupado. Pelos resultados obtidos, é possível afirmar que a floresta está em processo de regeneração, no estádio secundário inicial, e que existem agrupamentos vegetais. Conclui-se que o processo de restauração da floresta ciliar pode darse de forma natural, desde que seja garantido o isolamento de fatores desestabilizadores, preservando os processos naturais de estruturação das comunidades vegetais e interações bióticas.

Carotenóides totais em Pothomorphe umbellata (L.) Miq. cultivadas in vitro

The aim of the present work was to compare the content of carotenoids between callus and regenerated plants of Pothomorphe umbellate. Germinated seeds (40 days old) were inoculated in different concentrations and combinations of BAP (benzylaminopurine) and NAA (naphthalene acetic acid) in order to stimulate the callus' production. After 60 days of culture, the callus containing some shoots were transferred to organogenesis medium (GA 3 0.1 mg L -1, BAP 0.5 mg L -1) for 40 days. Next, they were subcultivated in a medium for seedling growth (without regulators) for 40 days. Callus (collected after 60 days) and seedlings (collected after 140 days) were frozen in liquid nitrogen and kept under -80°C for future carotenoids' analysis. The highest concentration of carotenoids was found in plants cultivated in medium without regulators. The callus did not showed difference concerning the culture medium; however, they presented lower content of carotenoids in relation to plants.

Frugivoria e dispersão de sementes por aves em áreas restauradas de diferentes idades no estado de São Paulo

Devido às crescentes pressões antrópicas sobre os ambientes naturais e o decorrente desmatamento, fragmentação florestal e extinções locais, diversos processos ecológicos importantes para a manutenção da biodiversidade estão sumindo. Diante de tal cenário a restauração ecológica vem avançando consideravelmente nas últimas décadas visando à recuperação de ambientes degradados e restituir os processos ecológicos intrínsecos das comunidades. Um dos principais processos intrinsecamente relacionados com a manutenção da integridade do ecossistema é a dispersão de sementes. Neste aspecto as aves oferecem uma enorme gama de serviços, funcionando como elos móveis que ativamente se deslocam na paisagem, conectando habitats no espaço e no tempo, mantendo sua memória e resiliência. Dessa maneira se faz necessário ter conhecimento se está havendo a retomada de interações ecológicas em áreas restauradas. No presente estudo foram estudadas as interações entre aves e plantas ornitocóricas através da frugívoria em três áreas de restauração de diferentes idades e um remanescente de vegetação como controle localizadas no interior do Estado de São Paulo. Foram registradas 25 espécies de aves consumindo frutos de 16 espécies de plantas ornitocóricas nas três áreas de restauração. As espécies de ave mais importantes das áreas de restauração foram Tangara sayaca, Turdus leucomelas, Pitangus sulphuratus, Myiozetetes similis e Elaenia flavogaster, todas de porte médio pequeno e de hábitos generalistas. Já as espécies mais importantes de plantas foram Cecropia pachystachia, Myrsine umbellata, Cytharexylum mirianthum, Trichilia clausenii e Schinus terebinthifolius. Deixando evidente que as principais espécies de aves presentes são de porte médio pequeno e as principais plantas possuem frutos e sementes pequenos... (Resumo completo, clicar acesso eletrônico abaixo)

Florística e fitossociologia de comunidades arbóreas em contato savana-floresta, Parque Estadual de Porto Ferreira (PEPF), Porto Ferreira, SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seedling fate across different habitats: the effects of herbivory and soil fertility

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Regeneração natural do componente arbóreo após a mortalidade de um maciço de taquara em um fragmento de floresta ombrófila mista em Lages - SC

The present study aimed to analyze the floristic and structural descriptors of tree species natural regeneration in a forest sector with synchronized bamboo (Merostachys multiramea Hackel) die-off (CT) and an adjacent area with continuous canopy cover (ST) in an araucaria forest fragment in the municipality of Lages, Santa Catarina state. A total of 14, 5x5m, plots (six plots in CT sector and eight in ST sector) were allocated, where all tree species regenerative individual with circumference at breast height smaller than 15cm and height higher than 25cm was measured (diameter at soil level) and identified. The richest families were: Myrtaceae (nine), Solanaceae (six) and Aquifoliaceae (four). The Shannon Diversity Index in ST and CT sectors were respectively 2.73 and 2.31. The species with the highest importance values in CT sector were Solanum variabile, Piptocarpha angustifolia, Mimosa scabrella, Jacaranda puberula and Solanum pseudoquina. In ST sector, the species with highest importance values were Myrsine lorentziana, Casearia decandra, Cinnamodendron dinisii, Drimys brasiliensis and Ilex paraguariensis. The results showed that the synchronized bamboo die-off influenced the spatial variation in the floristic and structural descriptors of the tree species natural regeneration.

AMS radiocarbon dates and pollen analysis of ODP Hole 175-1078C

ODP Site 1078 situated under the coast of Angola provides the first record of the vegetation history for Angola. The upper 11 m of the core covers the past 30 thousand years, which has been analysed palynologically in decadal to centennial resolution. Alkenone sea surface temperature estimates were analysed in centennial resolution. We studied sea surface temperatures and vegetation development during full glacial, deglacial, and interglacial conditions. During the glacial the vegetation in Angola was very open consisting of grass and heath lands, deserts and semi-deserts, which suggests a cool and dry climate. A change to warmer and more humid conditions is indicated by forest expansion starting in step with the earliest temperature rise in Antarctica, 22 thousand years ago. We infer that around the period of Heinrich Event 1, a northward excursion of the Angola Benguela Front and the Congo Air Boundary resulted in cool sea surface temperatures but rain forest remained present in the northern lowlands of Angola. Rain forest and dry forest area increase 15 thousand years ago. During the Holocene, dry forests and Miombo woodlands expanded. Also in Angola globally recognised climate changes at 8 thousand and 4 thousand years ago had an impact on the vegetation. During the past 2 thousand years, savannah vegetation became dominant.

Contribution of woody habitat islands to the conservation of birds and their potential ecosystem services in an extensive Colombian rangeland

The conservation of birds and their habitats is essential to maintain well-functioning ecosystems including human-dominated habitats. In simplified or homogenized landscapes, patches of natural and semi-natural habitat are essential for the survival of plant and animal populations. We compared species composition and diversity of trees and birds between gallery forests, tree islands and hedges in a Colombian savanna landscape to assess how fragmented woody plant communities affect forest bird communities and how differences in habitat characteristics influenced bird species traits and their potential ecosystem function. Bird and tree diversity was higher in forests than in tree islands and hedges. Soil depth influenced woody species distribution, and canopy cover and tree height determined bird species distribution, resulting in plant and bird communities that mainly differed between forest and non-forest habitat. Bird and tree species and traits widely co-varied. Bird species in tree islands and hedges were on average smaller, less specialized to habitat and more tolerant to disturbance than in forest, but dietary differences did not emerge. Despite being less complex and diverse than forests, hedges and tree islands significantly contribute to the conservation of forest biodiversity in the savanna matrix. Forest fragments remain essential for the conservation of forest specialists, but hedges and tree islands facilitate spillover of more tolerant forest birds and their ecological functions such as seed dispersal from forest to the savanna matrix.

Distribution of pollen and spores in sediments of ODP Hole 175-1078C

The distribution of pollen in marine sediments is used to record vegetation change on the continent. Generally, a good latitudinal correspondence exists between the distribution patterns of pollen in the marine surface sediments and the occurrence of the source plants on the adjacent continent. To investigate land-sea interactions during deglaciation, we compare proxies for continental (pollen assemblages) and marine conditions (alkenone-derived sea surface temperatures) of two high-resolution, radiocarbon-dated sedimentary records from the tropical southeast Atlantic. The southern site is located West of the Cunene River mouth; the northern site is located West of the Angolan Huambe Mountains. It is inferred that the vegetation in Angola developed from Afroalpine and open savannah during the last Glacial maximum (LGM) via Afromontane Podocarpus forest during Heinrich Event 1 (H1), to an early increase of lowland forest after 14.5 ka. The vegetation record indicates dry and cold conditions during the LGM, cool and wet conditions during H1 and a gradual rise in temperature starting well before the Younger Dryas (YD) period. Terrestrial and oceanic climate developments seem largely running parallel, in contrast to the situation ca. 5° further South, where marine and terrestrial developments diverge during the YD. The cool and wet conditions in tropical West Africa, South of the equator, during H1 suggest that low-latitude insolation variation is more important than the slowdown of the thermohaline circulation for the climate in tropical Africa.

Palynological and geochemical data of sediment core GeoB3910-2 located offshore Northeast Brazil

High resolution palynological and geochemical data of sediment core GeoB 3910-2 (located offshore Northeast Brazil) spanning the period between 19 600 and 14 500 calibrated year bp (19.6-14.5 ka) show a land-cover change in the catchment area of local rivers in two steps related to changes in precipitation associated with Heinrich Event 1 (H1 stadial). At the end of the last glacial maximum, the landscape in semi-arid Northeast Brazil was dominated by a very dry type of caatinga vegetation, mainly composed of grasslands with some herbs and shrubs. After 18 ka, considerably more humid conditions are suggested by changes in the vegetation and by Corg and C/N data indicative of fluvial erosion. The caatinga became wetter and along lakes and rivers, sedges and gallery forest expanded. The most humid period was recorded between 16.5 and 15 ka, when humid gallery (and floodplain) forest and even small patches of mountainous Atlantic rain forest occurred together with dry forest, the latter being considered as a rather lush type of caatinga vegetation. During this humid phase erosion decreased as less lithogenic material and more organic terrestrial material were deposited on the continental slope of northern Brazil. After 15 ka arid conditions returned. During the humid second phase of the H1 stadial, a rich variety of landscapes existed in Northeast Brazil and during the drier periods small pockets of forest could probably survive in favorable spots, which would have increased the resilience of the forest to climate change.

Pollen analysis of modern mangrove systems

Three sediment cores from the Bragança Peninsula located in the coastal region in the north-eastern portion of Pará State have been studied by pollen analysis to reconstruct Holocene environmental changes and dynamics of the mangrove ecosystem. The cores were taken from an Avicennia forest (Bosque de Avicennia (BDA)), a salt marsh area (Campo Salgado (CS)) and a Rhizophora dominated area (Furo do Chato). Pollen traps were installed in five different areas of the peninsula to study modern pollen deposition. Nine accelerator mass spectrometry radiocarbon dates provide time control and show that sediment deposits accumulated relatively undisturbed. Mangrove vegetation started to develop at different times at the three sites: at 5120 14C yr BP at the CS site, at 2170 14C yr BP at the BDA site and at 1440 14C yr BP at the FDC site. Since mid Holocene times, the mangroves covered even the most elevated area on the peninsula, which is today a salt marsh, suggesting somewhat higher relative sea-levels. The pollen concentration in relatively undisturbed deposits seems to be an indicator for the frequency of inundation. The tidal inundation frequency decreased, probably related to lower sea-levels, during the late Holocene around 1770 14C yr BP at BDA, around 910 14C yr BP at FDC and around 750 14C yr BP at CS. The change from a mangrove ecosystem to a salt marsh on the higher elevation, around 420 14C yr BP is probably natural and not due to an anthropogenic impact. Modern pollen rain from different mangrove types show different ratios between Rhizophora and Avicennia pollen, which can be used to reconstruct past composition of the mangrove. In spite of bioturbation and especially tidal inundation, which change the local pollen deposition within the mangrove zone, past mangrove dynamics can be reconstructed. The pollen record for BDA indicates a mixed Rhizophora/Avicennia mangrove vegetation between 2170 and 1770 14C yr BP. Later Rhizophora trees became more frequent and since ca. 200 14C yr BP Avicennia dominated in the forest.