Seed survival and dispersal of an endemic Atlantic forest palm: the combined effects of defaunation and forest fragmentation

About 45 palm species occur in the Atlantic forest of Brazil, and most of them are affected by loss of seed dispersers resulting from forest fragmentation and hunting. Here we report the effects of habitat loss and defaunation on the seed dispersal system of an endemic palm, Astrocaryum aculeatissimum. We evaluated seed removal, insect and rodent seed predation, and scatter-hoarding in nine sites, ranging from 19 ha to 79 000 ha. We report the seedling, juvenile and adult palm densities in this range of sites. Endocarps remaining beneath the parent palm had a higher probability of being preyed upon by insects in small, mostly fragmented and more defaunated sites. The frequency of successful seed removal, scatter-hoarding and consumption by rodents increased in the larger, less defaunated sites. Successful removal and dispersal collapsed in small (< 1000 ha), highly defaunated sites and frequently resulted in low densities of both seedlings and juveniles. Our results indicate that a large fraction of Atlantic forest palms that rely on scatter-hoarding rodents may become regionally extinct due to forest fragmentation and defaunation. Current management practices including palm extraction and hunting pressure have a lasting effect on Atlantic forest palm regeneration by severely limiting successful recruitment of prereproductive individuals.(c) 2006 the Linnean Society of London.

The role of the seed coat in phytochrome-controlled seed germination in Lactuca sativa L. cv. Grand Rapids

The effect of scarification with sodium hypochloride on light sensitivity in seeds of Lactuca sativa L. cv. Grand Rapids is presented in the paper. Light-requiring lettuce seeds germinated in both dark and continuous light after scarification and 36 degrees C pre-incubation restored light sensitivity at 25 degrees C. Curves of dose-response indicated that chemical scarification induced a change in the control of seed germination from Low Fluence Response to the Very Low Fluence Response. Pre-incubation at 36 degrees C return the control to the Low Fluence Response of phytochrome action.

Influence of light and temperature on seed germination of Cereus pernambucensis Lemaire (Cactaceae)

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

The role of the seed coat in the light sensivity in Raphanus sativus L. cv. redondo gigante seeds

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

Morphology and anatomy of developing fruits and seeds of Mammea americana L. (Clusiaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Massive seed predation of Pseudobombax grandiflorum (Bombacaceae) by parakeets Brotogeris versicolurus (Psittacidae) in a forest fragment in brazil

Here we report massive seed predation of Pseudobombax grandiflorum (Bombacaceae) by Botogeris versicolurus (Psittacidae) in a forest fragment in Brazil. The intensity of seed predation was very high when compared to other studies in continuous forest, perhaps resulting from a scarcity of resources in such areas. This scarcity may limit the range of parrot's diet to a few plant species. It suggests that studies of Psittacidae seed predation may be important for conservation of some plants in fragments.

Analysis of a hyper-diverse seed dispersal network: modularity and underlying mechanisms

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

Effects of frugivore impoverishment and seed predators on the recruitment of a keystone palm

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

Temperature Dependent Seed Germination of Dalbergia nigra Allem (Leguminosae)

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

Effects of some phenolic compounds on soybean seed germination and on seed-borne fungi

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

Seed predation of Virola bicuhyba (Schott) Warb. (Myristicaceae) in the Atlantic forest of south-eastern Brazil

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

Limit between stages I and II of a seed imbibition curve

O conhecimento das fases de absorção de água das diferentes espécies é importante em pesquisas objetivando melhorar a qualidade das sementes, utilizando tratamentos como condicionamento osmótico, pré-hidratação e uso de bioreguladores. O objetivo do presente trabalho foi estabelecer uma metodologia para determinar o limite entre a primeira e a segunda fase do processo, considerando o modelo W = f(t) - (a - w0)exp(-kt), utilizando testes estatísticos. O limite entre as duas primeiras fases do processo de absorção de água pelas sementes, foi determinado utilizando-se a distribuição assintótica de uma função de estimadores. O ponto a partir do qual esta diferença (W*) deixa de ser significativa foi determinado utilizando-se o teste estatístico T de Student. Para os dados utilizados como exemplo, tem-se o modelo ou =(0,434 + 0,00162 t) - (0,434 - w o)exp(-0,121 t), com r² = 0,98 e W* = (0,434 - w o) exp(-0,121 t). O valor de t encontrado (27,2 horas) é menor do que o valor determinado, considerando-se como critério para mudança de fase a diferença de 1% entre a assíntota e o valor estimado pelo modelo ajustado. Essa diferença de duas horas corresponde a 0,28% de água absorvida.

PHYTOCHROME CONTROLLED SEED-GERMINATION IN LIGHT INSENSITIVE SEEDS OF RAPHANUS-SATIVUS L CV REDONDO GIGANTE

Seed germination of Raphanus sativus is inhibited by light only under low water potential of the medium. Curves of fluence response to white, red and far-red lights demonstrated that the inhibition of seed germination is dependent on light irradiance being far-red light the more effective than the formers and the germination being inhibited by intermitent light indicates phytochrome involvement through the high irradiance reactions in the control of seed germination in radish seeds under water stress conditions.

Effects of microhabitat on palm seed predation in two forest fragments in southeast Brazil

The establishment of plants depends crucially on where seeds are deposited in the environment. Some authors suggest that in forest understory seed predation is lower than in gaps, and higher than at the forest edge. However, most studies have been carried out in large forest patches and very little is known about the effects of microhabitat conditions on seed predation in forest fragments. We evaluated the effects of three microhabitats (gaps, forest edge, and understory) on seed predation of two palm species (Euterpe edulis and Syagrus romanzoffiana) in two semi-deciduous forest fragments (230 and 2100 hat in southeast Brazil. Our objective was to test two hypotheses: (1) Low rodent abundance in small fragments as a result of meso-predator action levels leads to lower seed predation in small fragments. (2) Most mammal species in small fragments are generalists with respect to diet and habitat, so that seed predation is similar in different microhabitats (gaps, forest edge and understory) in the small fragment, but not in the larger one. The study community of small fragments is usually composed of generalist species (in diet and habitat aspects), so we expected the same rate of seed predation among microhabitats (gaps, forest edge and understory) in the tested smaller fragment. The experiment was carried out in the dry season (for E. edulis) and in the wet season (for S. romanzoffiana) in 1999. We conclude that post-dispersal seed predation in forest fragments can be directly connected with mammal communities, reflecting their historical and ecological aspects. (C) 2004 Elsevier SAS. All rights reserved.

Seed dispersal and germination of Cryptocarya moschata Nees & Martius Ex Nees, Ocotea catharinensis Mez and Endlicheria paniculata (Sprengel) Macbride (Lauraceae)

Data of seed dispersal and germination of the studied species are presented, comparing both observations from the wild and nursery. Fruits were collected from Carlos Botelho State Park (24 degrees 44' to 24 degrees 03'S, 47 degrees 46' to 48 degrees 10'W), south of São Paulo State, Brazil. O. catharinensis had low germination percentage, both in the wild and in nursery, and did not tolerate seed storage at low temperature. In nursery, diaspores with removed mesocarp of E. paniculata presented greater germination than those in entire fruits. The high levels of seedling mortality beneath mother-trees of C. moschata, when in comparison to those observed to established seedlings from diaspores dispersed by muriquis (Brachyteles arachnoides E. Geoffroy 1806, Cebidae, Primates), allied to the absence of juveniles in the understory, are in accord with the escape model of Janzen-Connel. In nursery, diaspores of C. moschata dispersed by the primates had greater germination, in smaller time, than those collected from mother-trees.