Changes in the vegetation and trade winds in equatorial Northwest Africa 140,000-70,000 yr B.P., as deduced from two marine pollen records

The deep-sea cores M 16415-2 and M 16416-2 at about 9°N off Sierra Leone were analysed palynologically for the time interval 140,000-70,000 yr B.P. Results were presented in absolute (pollen concentration and pollen influx) and relative diagrams (pollen percentage). In a previous study it was evidenced that in northwest Africa pollen is mainly transported to the Atlantic by wind, so that the efficiency of aeolian pollen transport (pollen flux) could be used to evaluate changes in the intensity of the northeast trade winds. The glacial episodes (represented by the oxygen isotope stages 6 and 4) are characterized by strong northeast trade winds, whereas the last interglacial (stage 5) is characterized by weak trade winds. The pollen influx diagram shows that the intensity of the trade winds increased slightly during the relatively cool intervals of stage 5 (viz. 5.4 and 5.2). Tropical forest had maximally expanded around 124,000 yr B.P. (stage 5.5), around 98,000 yr B.P. (transition of stage 5.3 to 5.2), and around 70,000 yr B.P. (first part of stage 4): an increasing delay of the response of tropical forest to global intervals with maximum temperature is apparent during the last interglacial. As tropical forests need continuous humidity, the record of tropical forest monitors changes in climatic humidity south of the Sahara. During the last interglacial, the southern boundary of the Sahara shifted only little: expansions and contractions of the tropical forest area are correlated with contra-oscillations of the grass-dominated savanna zone. Great latitudinal shifts of the desert savanna boundary, on the contrary, occurred during the penultimate glacial interglacial transition (around 128,000 yr B.P.) to the north, and during the last interglacial-glacial transition (around 65,000 yr B.P.) to the south.

Avaliação da compactação do solo no crescimento inicial de espécies florestais da caatinga

Despite the importance of the study of roots, little is known about the negative effects of soil compaction in the development of the Caatinga forest species. In this sense, the objective was to evaluate the initial growth of Mimosa caesalpiniifolia, Tabebuia caraiba and Erythina velutina in soil under varying levels of compression. The experiment was conducted in a greenhouse located at the Academic Unit Specialized in Agricultural Sciences, UFRN. To perform the experiment, was used Oxisoil of sandy loam texture, from forest trial Area Agricultural School of Jundiaí (EAJ) of the municipality of Macaíba-RN, in an experimental unit consisting of three overlapping PVC rings, 10 cm in diameter and 25 cm in height, with a central ring which has undergone compression. The experimental design was a randomized block with six replications, being tested four levels of soil compaction (1.35; 1.45; 1.60 and 1.80 kg.dm-³), evaluating the following variables: diameter, height, number of leaves, dry weight of shoot and root system in each layer of the vessels. Overall, the species M. caesalpiniifolia, T. caraiba and E. velutina had initial growth favored by treatment consists of uncompressed soil. The M. caesalpiniifolia and T. caraiba species proved relatively resistant to compaction of the soil does not undergo any significant reduction in root growth density equal to or less than 1.60 kg.dm-³, whereas E. velutina proved susceptible effects of soil compaction, with significant changes in root growth under soil densities equal to or greater than 1.45 kg.dm-³. Increased soil compaction caused the impediment to the expansion of taproot inside the experimental units, promoting the accumulation of roots in the upper layers of the soil for the studied species. The subsoil physical impediment changed the initial aerial growth of M. caesalpiniifolia and E. velutina, but did not influence the growth of air T. caraiba seedlings the tested compression levels.

Pollen and spore counts of sediment core GeoB12624

In tropical eastern Africa, vegetation distribution is largely controlled by regional hydrology, which has varied over the past 20 000 years. Therefore, accurate reconstructions of past vegetation and hydrological changes are crucial for a better understanding of climate variability in the tropical southeastern African region. We present high-resolution pollen records from a marine sediment core recovered offshore of the Rufiji River delta. Our data document significant shifts in pollen assemblages during the last deglaciation, identifying, through changes in both upland and lowland vegetation, specific responses of plant communities to atmospheric (precipitation) and coastal (coastal dynamics and sea-level changes) alterations. Specifically, arid conditions reflected by a maximum pollen representation of dry and open vegetation occurred during the Northern Hemisphere cold Heinrich event 1 (H1), suggesting that the expansion of drier upland vegetation was synchronous with cold Northern Hemisphere conditions. This arid period is followed by an interval in which forest and humid woodlands expanded, indicating a hydrologic shift towards more humid conditions. Droughts during H1 and the shift to humid conditions around 14.8 kyr BP in the uplands are consistent with latitudinal shifts of the intertropical convergence zone (ITCZ) driven by high-latitude Northern Hemisphere climatic fluctuations. Additionally, our results show that the lowland vegetation, consisting of well-developed salt marshes and mangroves in a successional pattern typical for vegetation occurring in intertidal habitats, has responded mainly to local coastal dynamics related to marine inundation frequencies and soil salinity in the Rufiji Delta as well as to the local moisture availability. Lowland vegetation shows a substantial expansion of mangrove trees after ~ 14.8 kyr BP, suggesting an increased moisture availability and river runoff in the coastal area. The results of this study highlight the decoupled climatic and environmental processes to which the vegetation in the uplands and the Rufiji Delta has responded during the last deglaciation.

Age model and pollen analysis from site GIK16867 in the northern Angola Basin

Sporomorphs and dinoflagellate cysts from site GIK16867 in the northern Angola Basin record the vegetation history of the West African forest during the last 700 ka in relation to changes in salinity and productivity of the eastern Gulf of Guinea. During most cool and cold periods, the Afromontane forest, rather than the open grass-rich dry forest, expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the Gulf of Guinea. Except in Stage 3, when oceanic productivity was high during a period of decreased atmospheric circulation, high oceanic productivity is correlated to strong winds. The response of marine productivity in the course of a climatic cycle, however, is earlier than that of wind vigour and makes wind-stress-induced oceanic upwelling in the area less likely. Monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run-off.

Pollen analysis of sediment core GIK16415-2 in the eastern tropical Atlantic

Palynological data of the marine core M 16415-2 show latitudinal shifts of the northern fringe of the tropical rain forest in north-west Africa during the last 700 ka. Savanna and dry open forest expanded southwards and tropical rain forest expanded northwards during dry and humid periods, respectively. Until 220 ka B.P., the tropical rain forest probably kept its zonal character in West Africa during glacials and interglacials. It is only during the last two glacial periods that the rain forest possibly fragmented into refugia. Throughout the Brunhes chron, pollen and spore transport was mainly by trade winds.

The status of weed biological control in Vanuatu

Biological control of weeds in Vanuatu began in 1935, with the introduction of the tingid Teleonemia scrupulosa to control Lantana camara. To date, nine biological control agents have been intentionally introduced to control eight weed species. Seven of these agents have established on their respective hosts while an eighth, Zygogramma bicolorata, an agent for Parthenium hysterophorus has only recently been released and establishment is unlikely. The fate of a ninth agent, Heteropsylla spinulosa, released for the control of Mimosa diplotricha is unclear. Six other biological control agents, including Epiblema strenuana which was first detected in 2014 on P. hysterophorus on Efate have spread into the country unintentionally. Control of the target weeds range from inadequate to very good. By far the most successful agent has been Calligrapha pantherina which was introduced to control Sida acuta and Sida rhombifolia. The beetle was released on 14 islands and managed to spread to at least another 10 islands where it has effectively controlled both Sida spp. Control of the two water weeds, Eichhornia crassipes by Neochetina bruchi and N. eichhorniae and Pistia stratiotes by Neohydronomus affinis, has also been fairly good in most areas. Two agents, T. scrupulosa and Uroplata girardi, were released on L. camara, and four other agents have been found on the weed, but L. camara is still not under adequate control. The rust Puccinia spegazzinii was first released on Mikania micrantha in 2012 and successfully established. Anecdotal evidence suggests that it is having an impact on M. micrantha, but detailed monitoring is required to determine its overall impact. Future prospects for weed biological control in Vanuatu are positive, with the expected greater spread of recently released agents and the introduction of new agents for P. hysterophorus, L. camara, Dolichandra unguis-cati and Spathodea campanulata.

Dinâmica da regeneração natural de áreas em restauração pela transposição de solo superficial de cerrado e de floresta estacional

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Ecologia, Programa de Pós-Graduação em Ecologia, 2015.

EVOLUÇÃO ESTRUTURAL DE BRACATINGAIS DA REGIÃO METROPOLITANA DE CURITIBA, PARANÁ, BRASIL

O objetivo deste trabalho foi estudar a evolução estrutural de espécies arbóreas em bracatingais, ao longo de vinte anos. A bracatinga ( Mimosa scabrella Benth.) é a espécie pioneira, de vida curta, que caracteriza os bracatingais. Sob as bracatingas forma-se um sub-bosque com outras espécies arbóreas, que vai assumindo o lugar da bracatinga com o passar dos anos e que é tratado como se fosse lenha da própria bracatinga, quando a área é cortada a cada 7 anos e a regeneração da bracatinga é novamente induzida com o uso do fogo. O processo de sucessão em bracatingais ainda não foi estudado e é útil identificar a idade em que as demais espécies passam a dominar o bracatingal. Trabalhou-se com 320 parcelas, distribuídas em bracatingais com idades variando de 3 a 20 anos, medidas entre 1998 e 2011. Foram medidos os DAP (diâmetro a altura do peito) e altura total de todas as espécies com DAP ≥ 5 cm. Observou-se que, aos 11 anos, o conjunto das espécies supera a bracatinga em número de indivíduos e aos 19 anos as espécies arbóreas já apresentam uma distribuição diamétrica semelhante ao de uma floresta em fase mais avançada. De forma geral observou-se que, após os 10 anos de idade, um bracatingal já começa a tomar forma de um capoeirão.

Florestas energéticas: parâmetros técnicos para elaboração de projetos no mercado de carbono.

As florestas têm papel importante na captura e estocagem de carbono da atmosfera através do processo fotossintético. Partindo desta premissa, são vislumbradas muitas oportunidades de participação das florestas no mercado de créditos de carbono, seja através de projetos de conservação das formações florestais remanescentes, seja através de projetos de substituição de combustíveis fósseis por fontes renováveis a partir de reflorestamentos comerciais. Projetos de conservação têm encontrado maior receptividade nos mercados voluntário de crédito de carbono e mais recentemente através de mecanismos tais como REDD (Redução de Emissões por Desmatamento e Degradação) e de Pagamento por Serviços Ambientais. Já os projetos que visam a substituição de combustíveis fósseis por produtos e resíduos de cadeias produtivas florestais têm encontrado mais oportunidades de comercialização de créditos de carbono através do MDL (Mecanismo de Desenvolvimento Limpo). Uma das atividades do projeto nacional em rede Florestas Energéticas, desenvolvidas na Embrapa Meio Ambiente (Jaguariúna-SP) é avaliar e sugerir oportunidades no mercado de carbono para as espécies florestais: Eucalyptus urophila S T Blake; Mimosa caesalpiniaefolia Benth; Acacia mangium Willd e Sclerolobium paniculatum Vogel. Através de consulta à literatura e aos especialistas sobre cada uma das espécies, foi elaborado um estudo técnico sobre a viabilidade de inserção dessas espécies florestais no mercado de carbono considerando-se os parâmetros técnicos necessários à elaboração de projetos florestais para o mercado de carbono. Como referência serão considerados os parâmetros requeridos pelas metodologias mais recentemente aprovadas pelo Conselho Executivo do MDL, relativas a projetos florestais. O objetivo primordial desse estudo é apontar as necessidades estratégicas de pesquisa e desenvolvimento visando a plena utilização dessas espécies como fontes de carvão vegetal com sustentabilidade econômica, social e ambiental.

Fitotoxicidade da fase orgânica e do composto majoritário obtidos da polpa dos frutos de Crescentia cujete L. (Bignoniaceae).

Avaliou-se a itotoxicidade do extrato etanólico (CETOH), da fase orgânica (CEA) e do composto majoritário, o ácido (E)-cinâmico (AC), obtidos da polpa dos frutos da espécie popularmente conhecida como cujuba, cuieira e/ou cabaça (Crescentia cujete L.) sobre a inibição da germinação de sementes, desenvolvimento do hipocótilo e radícula das plantas invasoras Senna obtusifolia (L.) Irwin & Barneby (mata-pasto) e Mimosa pudica Mill. (malícia). A fase orgânica na concentração de 0,5% inibiu em 100% a germinação das sementes das duas plantas invasoras. O AC que foi obtido da fase orgânica inibiu a germinação das sementes de S. obtusifolia em 95% e de M. pudica em 99% na concentração de 0,1%, com concentração (%) tóxica para inibição de 50% (CI50) da germinação das sementes iguais a 0,063 e 0,037%, respectivamente; e nos bioensaios de crescimento de plântula, o AC foi mais eiciente sobre a radícula da planta S. obtusifolia (com CI50 igual a 0,009%) e para a planta M. pudica os valores de CI50 foram de 0,097% e 0,117% para a radícula e hipocótilo, respectivamente. Essa pesquisa reforça o potencial itotóxico do ácido (E)-cinâmico, veriicado inicialmente na fase orgânica em acetato de etila (CEA) rica nesse fenilpropanoide.

Plantas forrageiras das caatingas: usos e potencialidades.

Coleta de analises; descricao e usos das especies: camaratuba, carqueija, catingueira-verdadeira, espinheiro/jacurutu/jiquiri, facheiro, favela/faveleira, feijao-brabo, imbuzeiro/umbuzeiro, juazeiro, jurema-preta, jurema-vermelha, macambira, mandacaru/mandacaru-de-boi, manicoba, marmeleiro/marmeleiro-preto, moleque-duro, mororo/unha-de-vaca, quebra-faca, sabia, sete-cascas/cascudo/pau-de-casca. Comentarios gerais e recomendacoes.

Potencial larvicida de extratos de plantas regionais no controle de larvas de Aedes Aegypti (Diptera:Culicidae)

Dengue, amongst the virus illnesses one can get by vectorial transmission, is the one that causes more impact in the morbidity and mortality of world s population. The resistance to the insecticides has caused difficulties to control of vector insect (Aedes aegypti) and has stimulated a search for vegetables with larvicidal activity. The biodiversity of Caatinga is barely known and it is potential of use even less. Some plants of this biome are commercialized in free fairs northeast of Brazil, because of its phytotherapics properties. The vegetables in this study had been selected by means of a questionnaire applied between grass salesmen and natives of the Serido region from Rio Grande do Norte state; culicids eggs had been acquired with traps and placed in container with water for the larva birth. Thirty larvae had been used in each group (a group control and five experimental groups), with four repetitions four times. The vegetables had been submitted to the processes of decoction, infusion and maceration in the standard concentration of 100g of the vegetable of study in 1l of H2O and analyzed after ½, 1, 2, 4, 8, 12, 24 and 48 hours for verification of the average lethal dose (LD50) from the groups with thirty larva. The LD50 was analyzed in different concentrations (50g/l, 100g/l, 150g/l, 200g/l e 300g/l) of Aspidosperma pyrifolium Mart. 48 extracts of rind, leaf and stem of the seven vegetal species: Aspidosperma pyrifolium Mart., Mimosa verrucosa Benth, Mimosa hostilis (Mart.) Benth., Myracrodruon urundeuva Allemão, Ximenia americana L, Bumelia sartorum Mart Zizyphus joazeiro Mart, had been analyzed. The extracts proceeding from the three methods were submitted to the freezedrying, to evaluate and to quantify substances extracted in each process. The results had shown that Aspidosperma pyrifolium Mart. and Myracrodruon urundeuva Allemão are the species that are more distinguished as larvicidal after 24 hours of experiment, in all used processes of extraction in the assays. The Zizyphus joazeiro Mart species has not shown larvicidal activity in none of the assays. In relation to the extraction method, the decoction was the most efficient method in the mortality tax of the A. aegypti larvae

The flora and vegetation in an area of the Caatinga in Taperuaba, Sobral, Ceará state, Brazil

The Caatinga, covering about 800.000 km2, is the predominant vegetation type of the semi-arid region of Brazil. The Caatinga biome comprises several phytophysiognomies and floristic compositions, with many endemic species, especially in Fabaceae, Cactaceae, Euphorbiaceae, Bignoniaceae e Combretaceae. Despite considerable advances, the Brazilian semi-arid needs more studies and inventories of biodiversity, especially the Ceará state. On the basis of these considerations, the present study aims to identify the flora and vegetation, in order to characterize the phytophysiognomy in an area of the Caatinga, in locality of Taperuaba, municipality of Sobral, Ceará, Brazil. Field work was conducted in March 2015 and 2016 respectively, in three transects. The life-forms were established in accordance of Raunkiaer´s system. The floristic list is composed of 87 species, distributed in 66 genera and 36 families. The flora comprises 22 Brazilian endemic species. The most representative family was Fabaceae with 15 species, followed by Malvaceae (7) Convolvulaceae (6), Euphorbiaceae (5) and Poaceae (5). The biological spectrum had a high proportion of therophytes (29,9%), chamaephytes (29,9%) and phanerophytes (26,4%). In the area were identified two phytophysiognomies: outcrops communities highlighting succulent phanerophytes (Pilosocereus chrysostele (Vaupel) Byles & G.D. Rowley subsp. cearensis P.J. Braun & Esteves and P. gounellei (F.A.C. Weber) Byles & Rowley), chamaephytes (Encholirium spectabile Mart. ex Schult. & Schult. f. and Lepidaploa chalybaea (Mart. ex DC.) H. Rob.) and therophytes (Mitracarpus baturitensis Sucre), mixed with communities including small trees and shrubs on deeper soil, composed of Cereus jamacaru DC., a succulent phanerophyte, and many woody phanerophytes, such as Cordia oncocalyx Allemão, Crateva trapia L., Mimosa caesalpiniifolia Benth., M. tenuiflora (Willd.) Poir., Poincianella bracteosa (Tul.) L.P. Queiroz and P. pyramidalis (Tul.) L.P. Queiroz.

Leguminosae na Unidade de Conservação Refúgio de Vida Silvestre Pedra da Andorinha, Sobral, Ceará, Brasil

Leguminosae com cerca de 650 gêneros e 19.000 espécies compreende a terceira maior família de angiospermas, superada apenas por Orchidaceae (20.000 spp.) e Asteraceae (24.000 spp.). Para o Brasil, são citados 222 gêneros e 2.803 espécies distribuídas nos diversos domínios fitogeográficos, e para região Nordeste estão registradas 1.085 espécies em 168 gêneros. No Ceará, são reportadas 340 espécies em 105 gêneros, dos quais Mimosa L. (26 spp.) é o mais diversificado. No bioma Caatinga, é a principal família de fanerógamas com 83 gêneros e 354 espécies, muitas das quais com diversas potencialidades de uso. Em virtude da importância deste táxon no contexto do semiárido, objetivou-se com este trabalho catalogar as Leguminosae ocorrentes em uma área de Caatinga no distrito de Taperuaba, Sobral, Ceará. O estudo foi realizado na Unidade de Conservação Refúgio de Vida Silvestre Pedra da Andorinha, localizada a 70 km da sede municipal e possuindo aproximadamente 600 ha. A área é composta por Caatinga em duas fitofisionomias: uma terrícola e outra rupícola. As expedições de coletas foram realizadas entre março/2015 e março/2016. Os espécimes foram identificados com o auxílio de literatura e sites especializados. O material encontra-se depositado no acervo do Herbário Prof. Francisco José de Abreu Matos (HUVA). Foram catalogadas 15 espécies em oito gêneros: Mimosa (4 spp.), Chamaecrista Moench (3 spp.), Poincianella Britton & Rose (2 spp.). Bauhinia L., Centrosema (DC.) Benth., Desmodium Desv., Senna Mill., Stylosanthes Sw. e Zornia J.F. Gmel. apresentaram uma espécie cada. Dentre as espécies coletadas, duas apresentam propriedades medicinais: B. forficata (Vogel) Fortunato & Wunderlin e M. tenuiflora (Willd.) Poir. Centrosema pascuorum Mart. ex Benth, Mimosa pudica (Humb. & Bonpl. ex Willd.) DC., Stylosathes humilis Kunth e Zornia cearensis Huber são tratadas como invasoras de cultivos. Entre as espécies com alto potencial forrageiro, estão Chamaecrista linearis (H.S. Irwin & Barneby) Afr. Fern. & E.P. Nunes e Desmodium tortuosum (Sw.) DC. Por outro lado, Senna obtusifolia (L.) H.S. Irwin & Barneby, é tóxica aos bovinos. Alguns estudos ainda sugerem que os extratos das raízes de Poincianella bracteosa (Tul.) L.P. Queiroz possuem atividade biológica sobre larvas de Aedes aegypti. Diante dos resultados, verificou-se que Leguminosae é a família mais representativa da área de estudo e que 11 espécies apresentaram algum uso ou potencialidade econômica.

Phytosociology of the remaining xerophytic woodland associated to an environmental gradient at the banks of the São Francisco river - Petrolina, Pernambuco, Brazil1

Floristic and phytosociological surveys were carried out for 12 months in the Embrapa-SPSB, Petrolina, Pernambuco, Brazil. A transect was laid on starting at the river bank extending for 790 m away from the river and divided into 140 10 × 10 m contiguous plots. In each plot, all standing plants, alive or dead, with stem diameter at soil level ? 3 cm and total height ? 1 m were sampled. Along this transect, an elevation range of 9.40 m was registered and five topographical environments were identified: riverside (MR), dike (D), floodable depression (DI), boundary terrace (TL) - all of them belonging to the fluvial terrace with Fluvic Neosol and Haplic Cambisol both silty textured eutrophic soils - and the inlander tableland (TS), with medium sandy-textured Red-Yellow Argisols. Fourty-eight species/morphospecies, distributed into 39 genera and 21 families, were identified. Four phytogeoenvironments (MR, D + TL, DI + TL, and TS) were registered based on environmental variations and floristic similarities among plots using cluster analyses. The MR environment showed the largest total density, total basal area, maximum and medium heights and maximum diameter. Moreover, it had 8.1% of plants with heights above 8 m against 0.6% for D + TL, 0.2% for DI + TL, and 0% for TS. The species with the largest importance value were Inga vera subsp. affinis (DC.) T.D. Pennington in MR, Mimosa bimucronata Kunth in D + TL and DI + TL and M. tenuiflora (Willd.) Poir. in TS.