Aldicir Scariot

Reproductive biology of the palm Acrocomia aculeata in Central Brazil

Phenology, floral biology, the reproductive system, and pollination of the macauba palm, Acrocomia aculeata were studied in Central Brazil. The species is arborescent, single-stemmed, and reaches heights of up to 16 m. Flowering occurs between August and December, peaking between October and November. Fruit fall (harvest) is between June and March, with a peak in November. Inflorescences are androgynous with marked protogyny. The basic pollination syndrome is by beetles, with wind playing a secondary role. The principal pollinators are Andranthobius sp. (Curculionidae), Mystrops cf mexicana (Nitidulidae) and Cyclocephala forsteri (Scarabaeidae). Cross-pollination between different individuals (xenogamy) accounts for most of the reproductive system. However, the species is self-compatible, with geitonogamy accounting for a significant percentage of fruit set. The combination of two pollination strategies (wind and insects) with a flexible reproductive system (crossand self-pollination) suggests that A. aculeata can be highly successful in the colonization of new areas, as is evidenced by the ample distribution of species in the Neotropics.

Flowering and fruiting phenologies of the palm Acrocomia aculeata: patterns and consequences

Fruit set, fruit production, and fruit fall of the arborescent palm Acrocomia aculeata were documented for the Distrito Federal in central Brazil in 1984-1986. Flowering began in August and extended to mid-December with the highest concentration of open inflorescences (>50% of the total) occurring from mid-October until mid-November. There was a significant correlation (Spearman rank correlation coefficient; r = 0.69; N = 8; P = 0.05) between flowering time and fruit set over the course of the reproductive season. The inflorescences that opened in October were those that produced highest fruit set, with fruit set mean of 25.4 percent (SD = 20.9) in the first half and 28.9 percent (SD = 24.4) in the second half of October. Overall, fruit set was less than 10.0 percent, although it ranged from 0 to 85.0 percent. Each infructescence produced about 60 fruits, but it ranged from 0 to 271 fruits. Fruit fall occurred for 6 to 10 months, generally concentrated from October to January.

Tropical dry-forest regeneration from root suckers in Central Brazil

Seed dispersal, predation, desiccation and seedling survival are strong bottlenecks that impede tropical forest recovery on abandoned agricultural lands (reviewed in Holl 2002). The ability to resprout after disturbances overcomes these barriers, as those individuals bypass the seed stage and have more vigorous shoots than seedlings (Bond & Midgley 2001, Kammesheidt 1999, Kennard et al . 2002). Resprouting is a particularly important recovery mechanism in tropical dry forests (reviewed in Vieira & Scariot 2006). There are a number of reasons why resprouting may be more important in dry forests than in rain forests, including slower decay rates of trunk bases (Ewel 1980), or adaptation of plants to drought (Bond & Midgley 2001, Sampaio et al . 1993).

Diversidade, estrutura e distribuição espacial de palmeiras em um cerrado sensu stricto no Brasil Central - DF

The diversity, structure and spatial distribution of palms in a cerrado sensu stricto was studied. Data were collected in 21 plots of 20 × 50 m distributed randomly over a 152 ha area (400 × 3800 m). The diameters were taken at 0.10 m above the level of the soil. The reproductive stage and height per individual were recorded. Six species of palms was identified and a total 1671 individuals in 2.1 ha. The total density of the species was 796 palms.ha-1, in particular Syagrus flexuosa (Mart.) Becc. (41.2%), S. petraea (Mart.) Becc. (21.7%) and S. comosa (Mart.) Mart. (11.2%). The most frequent were S. flexuosa and Allagoptera leucocalyx (Drude) O. Kuntze. The total basal area was 0.51 m2.ha-1. S. flexuosa showed the greatest VI. The height and diameter distributions were almost unimodal, with all species. The coefficient of correlation between diameter and height was low (r = 0.0002 to 0.1247). Syagrus comosa produced the largest height value (380 cm). Butia archeri stood out in diameter (6.8-21 cm). All species were fertile, particularly B. archeri (100%). The pattern of dispersal of all species was aggregated. A classification by TWINSPAN (eigenvalue 0.501) separated B. archeri, S. comosa, and S. petraea as preferential for a group of plots and A. campestris, A. leucocalyx, and S. flexuosa as indifferent. It was concluded that the cerrado contains a rich and abundant flora of palms with morphological and structural differences that requires further research to determine patterns of diversity and structure of palms for the biome.

Edge effect on tree diversity, composition and structure in a deciduous dry forest in Central Brazil

The effects of edge distance on the structure, composition and diversity of tree community, considering individuals of all size classes, were studied in a well-preserved fragment of deciduous dry forest in northeastern Goias state, Brazil. Plots were systematically established at six distances (0, 40, 80, 160, 280 and 400 m) from the edge, over 10 orthogonal transects on the forest-pasture edge. It was sampled 602 adult individuals/ha, 8,927 saplings/ha and 54,167 seedlings/ha distributed in 58 species. Although the composition of seedlings and adult individuals varied significantly over the forest-pasture gradient, the variation explained by edge distance was below 4%. Among parameters of community structure and tested diversity indexes, there was significant variation only for diversity of seedlings and height of adult trees among forest-pasture edge distances. The dry forest fragment showed only a slight edge effect on the evaluated tree community parameters. This conclusion contrasts with findings from studies on tropical rain forests which indicate sharp differences between edge and interior tree communities in forest fragments.

Weedy and secundary palm species in central amazonian forest Fragments

Forest fragmentation may affect the abundance and distribution of organisms. Some species populations decrease being eventually driven to local extinction while other species may experience population increase. In a survey of the composition and abundance of secondary and weedy palms in eight forest fragments (three of 1-, three of 10- and two of 100-ha), in three sites (Dimona, Porto Alegre and Esteio) in central Amazonia, five native palm species which do not occur in the continuous forest were identified. Three were secondary species (Astrocaryum acaule Mart., Bactris maraja Mart. var. maraja and Bactris sp), one weedy (Lepidocaryum tenue Mart.), and one of unknown status (B. oligocarpa Barb. Rodr. & Trail). The highest abundance was found in the 1-ha fragments which had 172 of the 206 palms found compared with 33 in the 10-ha and one in the 100-ha fragments. However, most of these palms occur in the Dimona site, which accounted for 195 of the 206 of the individuals, compared with seven in Esteio and four in Porto Alegre. The weedy L. tenue, which forms clonal populations, although occurring only in Dimona, accounted for 91% of the individuals recorded. It is possible that with increased habitat degradation of small fragments, some populations of secondary and weedy species will also increase, what may be detrimental to the closed forest plant species populations occurring in forest fragments.

A FLÓRULA DA RESERVA DUCKE, I: PALMAE (ARECACEAE)

This is the first taxomomic treatment of a family for the Fiorala of the Ducke Reserve. Fourteen genera with 35 species are treated for the palm family, with keys to all genera and species and brief descriptions of all species. The keys are based on characters found on fertile herbarium specimens. Listed by decreasing diversity, the genera are: Bactris(8), Geonoma(6), Astrocaryum(5), Attalea(3), Oenocarpus(3), Euterpe(2), Desmoncus(1), Hyospathe(1), irianella(1), Manicaria(1), Mauritia(1), Mauritiella(1), Socratea(1) and Syagrus(1).

Produção e germinação de sementes de "capim dourado", Syngonanthus nitens (Bong.) Ruhland (Eriocaulaceae): implicações para o manejo

A venda de artesanato feito com escapos de S. nitens e uma importante fonte de renda na regiao do Jalapao, TO. Conhecer a epoca de producao e dispersao das sementes, bem como seu potencial germinativo, e essencial para propor formas de manejo que garantam a sustentabilidade economica e ecologica deste extrativismo. Com o intuito de caracterizar a epoca de producao de sementes foram coletados capitulos entre agosto e dezembro/2003. Foram realizados experimentos de germinacao em câmara a 22-30 oC, sob foto e termoperiodo de 12 horas, e tambem em condicoes de escuro. Caracterizou-se tambem a germinacao em condicoes de hipoxia (imersao em agua) e acidez (pH 4 e 5). A producao de sementes iniciou-se em setembro e a maior parte da dispersao ocorreu entre outubro e novembro. A germinacao das sementes coletadas entre setembro e outubro foi de 92 ± 7% (media ± DP), sementes coletadas a partir de novembro tiveram germinacao significativamente menor. A acidez e a hipoxia nao afetaram negativamente a germinacao em relacao ao controle. As sementes sao fotoblasticas positivas e mantem a germinacao apos congelamento a -20 oC. A colheita de escapos apos a frutificacao (a partir do final de setembro) e a dispersao manual das sementes pelos proprios extrativistas no momento da colheita sao estrategias importantes para o manejo da especie e nao prejudicam a atividade artesanal que esta focada nos escapos e nao nas flores, como ocorre para outras sempre-vivas.

Growth and reproduction of the understory palm Geonoma schottiana Mart. in the gallery forest in Central Brazil

Para compreender os fatores que influenciam o crescimento e a reproducao de Geonoma schottiana em mata de galeria no Brasil Central, foram levantadas duas hipoteses: (i) a producao de folhas e de estruturas reprodutivas esta concentrada no periodo do ano de maior insolacao; (ii) a producao de folhas e a atividade reprodutiva estao relacionadas ao comprimento do individuo. Entretanto, espera-se encontrar uma reducao brusca nas atividades de crescimento e reproducao em individuos mais altos devido aos efeitos da senilidade. O crescimento e a reproducao ocorreram concentrados na estacao seca, quando a insolacao e maior do que na estacao umida. Assim, a producao de folhas e inflorescencias de G. schottiana no sub-bosque de matas de galeria pode ser mais limitada pela luminosidade do que pela umidade do solo. Conforme o individuo cresce, o numero de folhas e a area foliar aumentam, mas a atividade reprodutiva foi independente do comprimento do individuo. Os recursos armazenados no estipe sao importantes para o crescimento, embora os fatores exogenos, como a abertura do dossel, possam ser mais importantes para a reproducao do que os carboidratos armazenados. A senilidade dos individuos parece ter um efeito menor na producao de estruturas vegetativas e reprodutivas ao contrario do que o tem sido detectado em especies co-genericas com maior atividade clonal.

Sustainable Harvest of Mangaba ( Hancornia speciosa ) Fruits in Northern Minas Gerais, Brazil

Sustainable Harvest of Mangaba (Hancornia speciosa) Fruits in Northern Minas Gerais, Brazil. The harvesting of non–timber forest products can contribute to conserving biodiversity and improving quality of life for rural communities. However, overexploitation can generate negative impacts on harvested populations, demanding the establishment of sustainable management practices. We estimated the maximum sustainable harvest of Hancornia speciosa Gomes (Apocynaceae) fruits in a savanna in northern Minas Gerais state, Brazil. The structure and population dynamics were analyzed in 70 permanent plots (20 x 50 m) in the years 2008–2011. A matrix population model based on life stages (seedlings, saplings, adults 1, adults 2) was used to calculate the population growth rate (λ), the stable stage distribution and the elasticity, and to simulate the effects of different fruit harvesting levels. The population growth rate (λ) value was 1.02 (CI95% 0.98 to 1.05), the maximum sustainable fruit harvest rate was 87%, and the elasticity analysis indicated that survival of the larger–size adults is the most important parameter to maintain the population. Apparently, the H. speciosa population is stable, which may indicate that the current harvesting level is not affecting population regeneration. However, other natural or anthropic disturbances, such as charcoal production and fire, can increase adult mortality, leading to population decline.Extrativismo sustentável de frutos de mangaba (Hancornia speciosa) no norte de Minas Gerais, Brasil. O extrativismo de produtos florestais não madeireiros pode contribuir para conservar a biodiversidade e melhorar a qualidade de vida de comunidades rurais. Entretanto, a exploração excessiva pode impactar negativamente as populações exploradas, o que demanda o estabelecimento de práticas sustentáveis de manejo. Para estimar a taxa máxima de coleta sustentável dos frutos de Hancornia speciosa Gomes (Apocynaceae) realizamos um estudo em uma área de cerrado no norte do estado de Minas Gerais, Brasil. A estrutura e a dinâmica populacional foram analisadas em 70 parcelas permanentes (20 x 50 m) nos anos 2008–2011. Modelos de matriz populacional baseados em estágios de vida (plântulas, juvenis, adultos 1 e adultos 2) foram utilizados para calcular a taxa de crescimento populacional (λ), a distribuição estável de classes, a elasticidade e para simular os efeitos de diferentes níveis de coleta de frutos. A taxa de crescimento populacional (λ) foi 1.02 (IC95% 0.98 a 1.05), a taxa máxima de coleta sustentável é de 87% dos frutos e a análise de elasticidade mostrou que a sobrevivência dos adultos de maior tamanho é o parâmetro mais importante para a manutenção da população. Aparentemente a população de H. speciosa está estável, o que pode ser um indicativo de que o extrativismo praticado não está afetando a regeneração da população. Porém, outros distúrbios naturais ou antrópicos, como a produção de carvão e o fogo, podem aumentar a mortalidade de adultos levando a um declínio populacional.