Andréa Lúcia Teixeira de Souza

DISTRIBUTION OF SPIDERS ON DIFFERENT TYPES OF INFLORESCENCES IN THE BRAZILIAN PANTANAL

Abstract Reproductive stems add complexity to vegetation, thereby increasing the range and quality of microhabitats available for arthropods. In this study, we evaluated whether variation in inflorescence characteristics influenced spider distribution. We compared spider guild structure among inflorescences of three herbaceous plant species, Melanthera latifolia, Conyza bonariensis and Eupatorium hecatanthum (Asteraceae), and between inflorescences of C. bonariensis in two different phenological stages, flower buds and opened flowers. Total spider abundance was higher on M. latifolia, intermediate on E. hecatanthum, and lower on C. bonariensis. Ambush spiders were more abundant on M. latifolia than on the other plant species, while the abundance of hunting spiders did not differ among plant species. Also, spiders recorded on M. latifolia were larger than those on both E. hecatanthum and C. bonariensis. However, ambush spiders were smallest on M. latifolia, while hunting spiders on E. hecatanthum were larger than on the other plant species. The number of spiders on inflorescences with flower buds did not differ from those with opened flowers, but ambush spiders on inflorescences with opened flowers were larger than those on inflorescences with flower buds. Our results with different inflorescence types support the hypothesis that differences on microhabitat structure influence distribution of spiders.

Tamanho de frutos e de sementes e sua influência na germinação de jatobá-do-cerrado (Hymenaea stigonocarpa var. stigonocarpa Mart. ex Hayne, Leguminosae - Caesalpinoideae)

Neste estudo foi descrito a biometria de frutos e de sementes de uma populacao de Hymenaea stigonocarpa var. stigonocarpa foi avaliado o efeito da massa de sementes na proporcao e no tempo de germinacao, sob condicoes de laboratorio (câmara de germinacao) e em viveiro, considerando como criterios de germinacao a protrusao da raiz primaria e a expansao de eofilos. Esta populacao de jatoba-do-cerrado apresentou uma grande variacao no tamanho de frutos e de sementes. A massa das sementes variou entre 0,546 e 7,666 g e estas foram classificadas em pequenas, medias e grandes. Uma proporcao maior de sementes classificadas como medias, emitiu a raiz primaria em relacao as grandes, enquanto as pequenas ocuparam posicao intermediaria. A massa de sementes nao influencia a proporcao de sementes que apresenta expansao de eofilos. As sementes grandes emitem a raiz primaria mais rapidamente que as pequenas. O tempo medio da expansao de eofilos decresce com a reducao da massa de sementes. Apesar das sementes medias e pequenas possuirem maior potencial para expor a raiz primaria, estas apresentam maior taxa de mortalidade na transicao entre as fases de protrusao da raiz primaria e de expansao de eofilos.

Morfologia de frutos, sementes e desenvolvimento de plântulas e plantas jovens de Maclura tinctoria (L.) D. Don. ex Steud. (Moraceae)

This study describes the morphological aspects of fruits and seeds, and the development of seedlings and saplings of Maclura tinctoria. The biometry of fruits and seeds was described from 100-unit samples, and germination tests were carried out in a germination chamber and also in the greenhouse. The fruit is oblong and is formed by compressed nutlets, with a sweet, fleshy pericarp; it is indehiscent, and greenish-yellow when mature. The mature seed is laterally flattened, slightly oval, cream-colored and with a smooth surface. Germination rates were high, both in the germination chamber (92%) and the greenhouse (90%). Initial seedling morphology follows the epigeous-phanerocotylar type. Saplings have simple, alternate leaves, which are slightly oval and membranous, pilose, serrulate, with acute apex and rotund base. Venation is pinnate with a semi-craspedodromous pattern. These results allow easy identification of this species in seedling banks and for future studies of forest restoration.

Aspectos morfológicos de frutos, sementes e desenvolvimento de plântulas e plantas jovens de Unonopsis lindmanii Fries (Annonaceae)

Unonopsis lindmanii is a small tree restricted to riparian forests in Central Brazil. Here we describe the morphological characteristics of the fruits and seeds, and the development of seedlings. The multiple, indehiscent fruits are apocarpous, unattached to one another, with a fleshy pericarp, and the seeds are darkish brown and discoid in shape, with an ornamented, rugose tegument. Germination is slow and irregular, and rates are very low in the germination chamber (3%). They are high in the greenhouse (70%) suggesting positive photoperiodism. Initial seedling morphology is cryptocotyledonar-epigeous. Saplings have simple, alternate leaves with short petioles, and are symmetric, membranous, and elliptical. The venation pattern is of the brochidodrome-camptodrome type. These results help to identify the species in the field, and may also contribute to community description studies. Because it is dispersed by birds, this species is an excellent option for use in restoration projects of degraded areas.

Superação de dormência de sementes como estratégia para restauração florestal de pastagem tropical

O objetivo deste trabalho foi avaliar a influencia de tratamentos de superacao da dormencia de sementes sobre a taxa e o tempo de emergencia de especies arboreas de Fabaceae, e sobre seu estabelecimento, quando reintroduzidas em pastagem, no Cerrado. Foram realizados experimentos em casa de vegetacao e em campo (pastagem de Urochloa brizantha ), com as especies Mimosa caesalpiniifolia , Peltophorum dubium , Pterogyne nitens , Dimorphandra mollis , Copaifera langsdorffii e Hymenaea stigonocarpa , submetidas ou nao aos seguintes tratamentos de superacao de dormencia: D. mollis e H. stigonocarpa , escarificacao mecânica; C. langsdorffii e M. caesalpiniifolia , escarificacao quimica com H2SO4; P. nitens , puncao do tegumento; e P. dubium , imersao em agua a 80oC. O estabelecimento em campo foi monitorado por 21 meses. A superacao de dormencia promoveu, em casa de vegetacao, maior emergencia de quatro das seis especies avaliadas, e, no campo, de cinco especies. Alem disso, reduziu o tempo de emergencia das especies e aumentou o recrutamento de M. caesalpiniifolia , P. nitens , D. mollis e H. stigonocarpa , aos 127 dias, e de H. stigonocarpa aos 659 dias. Os tratamentos de superacao de dormencia podem aumentar a eficiencia da semeadura direta, em projetos de restauracao de areas degradadas no Cerrado, ao promover maior emergencia das sementes e o estabelecimento das plantas.