Maria Lúcia Absy

Community Structure of Woody Plants of Roraima Savannahs, Brazil

Patterns of diversity and community organisation of woody species ofsavannahs in Roraima, northern Brazil, were investigated, to relate structuraldata with edaphic factors and to analyse floristic relationships usingclassification and ordination techniques. The species studied refer to aninventory of 45 plots of 150 × 10 m (0.15 ha)distributed in the Roraima savannahs. We identified 13,410 woody individuals,belonging to 30 families, 52 genera and 71 species. The percentage of rarespecies is high, 58%. The richness, diversity, density and basal area of thestudied plots suggest that Roraima savannahs are poor in species. The mostimportant species include element dwarf shrubs (Byrsonimaverbascifolia, Tibouchina aspera andCassia obtusifolia), shrubby (Psidiumguianense, Randia formosa, Caseariasylvestris, Erythroxylum suberosum,Tocoyena formosa and Mimosamicrocephala) and arboreal (Curatellaamericana,B. crassifolia, B. coccolobifolia,Bowdichia virgilioides, Roupalamontana, Antonia ovata, Genipaamericana, Vitex schomburgkiana,Peltogyne campestris, Xylopiaaromatica and Himatanthus articulatus).Correlation between edaphic factors and vegetation indices reveal that densityseems to be more sensitive to edaphic factors than to basal area and diversity.Density correlated significantly with levels of Al, K and the quantity of sandin the soil. Edaphic factors can explain the distribution and importance ofsomespecies, such as: B. virgilioides, R.montana and P. guianense. Classificationanalysis tended to confirm PCA results, separating Roraima savannahs into threelarge clusters. This suggests that ecological differentiation is based not onlyon species density but also on basal area. Ordination describes floristicvariation but does not identify all edaphic gradients.

Plantas nectaríferas utilizadas por duas espécies de Melipona da Amazônia

Analisa-se o nectar de 302 abelhas de Melipona seminigra merrillae Cock. e 302 de abelhas de Melipona rufiventris paraensis Ducke, durante o periodo de maio de 1977 a abril de 1978, em Manaus. Do total de amostras estudadas de M. seminigra e M. rufiventris, 16 (5,3%) e 11 (3,6%) respectivamente, nao continham polen. Das 286 restantes (94,7%) de M. seminigra, 80 (28%) apresentavam polen de uma so especie, 88 (30,8%) de duas especies e 118 (41,2%) de tres ou mais. De 291 (96,4%) restantes de M. rufiventris, 33 (11,3%) apresentavam polen de uma so especie, 54 (18,6%) de duas especies e 204 (70,1%) de tres ou mais. Os graos de polen encontrados nas amostras de nectar representam ao todo 60 tipos morfologicos, distribuidos em 29 familias, pelo menos 42 generos diferentes, dos quais 39 foram separados ao nivel de especie. Sugere-se que a maior porcentagem de visitas, a mais de uma especie de plantas nectariferas (72%) do que a plantas poliniferas (39%), seja devida a estrategias das plantas unissexuais para obrigar a abelha visitar plantas masculinas para polen na manha e femininas para nectar mais tarde.

Recurso polínico coletado por abelhas sem ferrão (Apidae, Meliponinae) em um fragmento de floresta na região de Manaus - Amazonas

O recurso polinico coletado por operarias de Melipona seminigra merrillae Cockerell, Melipona fulva Lepeletier, Trigona fulviventris (Smith) e CephaloTrigona femorata Guerin, no Campus da UFAM, Manaus (AM) foi estudado no periodo de marco a outubro de 2001. Noventa tipos polinicos foram coletados pelas abelhas, distribuidos em 31 familias, 67 generos e 10 formas Tipo. Trigona fulviventris diversificou mais suas coletas, utilizando 58 fontes no periodo. O tamanho do nicho polinico utilizado pelas abelhas ficou assim distribuido: T. fulviventris (58), M.s. merrillae (41), C. femorata (34) e M. fulva (25). Dos tipos determinados, os que mais contribuiram para a dieta das abelhas, apresentando as maiores frequencias nas amostras de polen, foram Miconia myriantha (12,91%), Leucaena leucocephala (9,52%), Tapirira guianensis (6,53%), Eugenia stipitata (6,22%), Protium heptaphyllum (6,17%) e Vismia guianensis (5,93%). As abelhas de modo geral concentraram suas coletas em um numero reduzido de especies vegetais e com um grau diferenciado de uso para cada uma das fontes. Tipos polinicos com frequencia acima de 10% ocorreram em pequena proporcao na maioria dos meses, sendo responsaveis por mais de 50% do total do polen coletado em cada mes. A utilizacao das fontes de polen variou conforme a especie. T. fulviventris teve uma dieta mais ampla e diversificada, enquanto M. fulva foi a que menos diversificou suas coletas. T. fulviventris apresentou maior uniformidade no uso das fontes polinicas e a sobreposicao de nichos polinicos foi maior entre M.s. merrillae e M. fulva e menor entre T. fulviventris e C. femorata.

Physiognomy of the savannas of Roraima, Brazil.

Forty five plots of 0,15ha (10 X 150m) distributed in the savannas of Roraima were analysed for physiognomy and their relationship to the edaphic characteristics of the surface soil. Quantitative measures of height, frequency, basal area and density of woody elements and qualitative measures of spatial distribution and % cover of tree/shrubs were used. The plots were classified in to four physiognomic types (grassland, tree and shrub savanna, woodland savanna and park savanna) each with very defined structural characteristics. The survey found 267 species , belonging to 55 families, 137 genera, 195 herbaceous species and 71 woody species. Among the woody, 51% were tree , 32% shrub and 17% dwarf shrubs. The herbaceous stratum is the richest, with 41 families, 98 genera and 207 species. However, only 18 species were found in more than 20% of the plots. Eighty percent of the plots classified as grassland were found on sandy soils, 81% of the tree and shrub savanna on clay soils, 64% of the woodland savanna on sandy soils and all the parks savannas were found on soils of loamy sand. However, the physiognomic types did not possess significant relationships with most of the analyzed nutrients; only the levels of A1+++, in the surface layer (0-10cm depth), were significantly different among the physiognomic types. That significant difference was due mainly to the differences found between the levels of A1+++ of the grassland and tree and shrub savanna and between the grassland and woodland savannas.

Espécies nectaríferas e poliníferas utilizadas pela abelha Melipona compressipes fasciculata (MELIPONINAE, APIDAE), no Maranhão

This paper lists 79 species of plants used by Melipona compressipes fasciculata, the most common bee of Maranhao (a northern Brazilian State). Most of these plants are also visited by Apis Mellifera. Certain plant species are suggested for planting along roadsides, streets, avenues and town parks to increase the bee-exploited flora.

Polinizadores de Bertholletia excelsa (Lecythidales: Lecythidaceae): interações com abelhas sem ferrão (Apidae: Meliponini) e nicho trófico

This paper presents an analysis of the foraging behavior and interactions of Xylocopa frontalis Olivier (Apidae: Xylocopini) and Eulaema mocsaryi (Friese) (Apidae: Euglossini) in the presence of stingless bees (Apidae: Meliponini) in flowers of Bertholletia excelsa, the Brazilian nut. The palynological load carried by both species was also examined. This study was conducted in the farm Aruanã, Itacoatiara/ Amazonas state, Brazil, during the flowering peak of B. excelsa. The visitation by the main pollinators X. frontalis and E. mocsaryi were influenced by the presence and activities of stingless bees in the flowers of B. excelsa. Meliponini bees did not have any effect on the visits and collection of floral resources by X. frontalis, while negatively affecting the number of visits by E. mocsaryi. The stingless bees presented a variety of strategies to get access to pollen grains of B. excelsa, grouped into two categories: opportunism -Frieseomelitta trichocerata Moure, Tetragona goettei (Friese), and Tetragona kaieteurensis (Schwarz), and stealing -Trigona branneri Cockerell, Trigona fuscipennis Friese, and Trigona guianae Cockerell. The palynological analysis from X. frontalis showed that the bee collected pollen in a few species of plants, but mainly on B. excelsa. The pollen grains of B. excelsa were poorly represented in the pollen shipments of E. mocsaryi, due to its large trophic niche in the locality.

Bees visitors of three species of Clusia (Clusiaceae) flowers in Central Amazonia

Observations on bees visitors to three species of Clusia (Clusiaceae) flowers in the Reserva Adolpho Ducke, Manaus, Amazonas, Brazil were made during three two-week periods. The three species of Clusia, namely C. grandiflora, C. panapanari and C. insignis, presented variations regarding the species of bee visitors. A total of 23 bee species visited the three species of Clusia. The Euglossini and Meliponinae bees were the most frequent visitors of the Clusia flowers. Bee collecting behavior of floral resources is described.

Analyses of pollen found in honey samples of Apis mellifera L. (Hymenoptera, Apidae) in a savanna area in Roraima, Brazil

Foram analisadas amostras de mel de um apiario localizado na Aldeia do Contao, Roraima, Brasil. As amostras foram obtidas das colheitas nos meses de outubro e dezembro de 1996 e janeiro, fevereiro e marco de 1997. Foram identificados um total de 20 tipos polinicos distribuidos em 18 generos e 13 familias. As familias: Mimosaceae (4 especies), Anacardiaceae (3 especies), Sterculiaceae (2 especies), Caesalpiniaceae (2 especies) e Amaranthaceae (2 especies) foram as mais representadas, as demais por uma unica especie. Os tipos polinicos mais frequentes foram: Mimosa polydactyla H.B.K (outubro e dezembro de 1996), Curatella americana L. (janeiro, fevereiro e marco de 1997). Encontrou-se tres correlacoes significativas entre as frequencias dos tipos polinicos de: Curatella americana L. X Mimosa polydactyla H.B.K (r = -0,99), Curatella americana L. X Astronium sp (r = 0,95) e Mimosa polydactyla H.B.K e Astronium sp (r = -0,91)

Morfologia polínica de espécies de várzea e de igapÓ da Amazônia Central

Foi estudada a morfologia dos graos de polen de dez especies de plantas de varzea e igapo provenientesda Ilha da Marchantaria e Taruma-Mirim, localizadas a 20 Km da cidade de Manaus (AM), coletadas nos periodos de abril a agosto de 2000 e agosto de 2001. As especies descritas foram Cassia leiandra Benth. (Caesalpiniaceae), Campsiandra comosa var. laurifolia (Benth.) Cowan (Caesalpiniaceae), Hevea spruceana (Benth.) Mull. Arg. (Euphorbiaceae), Piranhea trifoliata Baill. (Euphorbiaceae), Laetia corymbulosa Spruce ex Benth. (Flacourtiaceae), Eschweilera tenuifolia (O. Berg) Miers (Lecythidaceae), Acacia polyphylla DC. (Mimosaceae), Inga micradenia Spruce ex Benth. (Mimosaceae), Simaba orinocensis Kunth (Simarubaceae), Vitex cymosa Bert. ex Spreng. (Verbenaceae). A analise polinica constatou que estas especies possuem graos de polen com caracteristicas morfologicas bastante variadas.

Interactions between carpenter bees and orchid bees (Hymenoptera: Apidae) in flowers of Bertholletia excelsa Bonpl. (Lecythidaceae)

Competition between two species of bees for the same type of floral resource may generate antagonistic behavior between them, especially in cultivated areas where food resources are limited, seasonally and locally. In this study, was tested the hypothesis of antagonism between two solitary bee species of the family Apidae, Eulaema mocsaryi (Euglossini) and Xylocopa frontalis (Xylocopini), visiting the Brazil nut flowers (Bertholletia excelsa: Lecythidaceae) in a central Amazonia agricultural area. The visitation time was analyzed to detect the possible temporal overlap in the foraging of these bees. Furthermore, was analyzed their interspecific interactions for manipulating flower species visited by an opponent species, as well as attempts to attack this opponent. The individuals of Xylocopa frontalis visited the Brazil nut flowers before Eulaema mocsaryi, although the peak visitation of both did not presented significant differences. Neither of the species manipulated flowers recently visited by opponent species, and there were practically no antagonistic interactions between them. Thus, X. frontalis and E. mocsaryi shared the same food source in the flowers of B. excelsa due to differences in their time of visits and non-aggressive way of interacting with the opponent. This result has important implications for pollinating the Brazil nut, and a possible management of X. frontalis and E. mocsaryi, since these two were the most abundant pollinators in the studied locality.