Tree species which sprouted from root buds were identified in a 3.6ha area of a Semideciduous Seasonal Forest fragment in Campinas, São Paulo State (22° 55' S and 47° 05' W)

ABSTRACT(Floristic composition of a savanna community in Rio Grande do Norte, northeastern Brazil). In the municipality of Rio do Fogo (in 1976) a savanna community was registered by radar that, until now, has not been studied in loco. Some questions were asked about this community: Is this area Cerrado, floristically? What is the phytogeography of plant species in this community? Do rare, endemic or endangered species occur in this community? To answer these questions a floristic inventory, from August 2007 to September 2009, was performed in 400 ha of this region. The data indicated that of the 94 species recorded, 73 are associated with Cerrado, 69 also with Caatinga, 60 with Atlantic Forest, 47 with Amazonian forest, 14 with the Pantanal and 11 with the Pampa flora. Thirty-nine species are first listed for Rio Grande do Norte (RN); Stylosanthes gracilis Kunth (Fabaceae) and Aristida laevis (Nees) Kunth (Poaceae) are first records for the Northeast of Brazil. Aspilia procumbens Baker (Asteraceae) showed a restricted distribution in the state and is listed as critically endangered. Stilpnopappus cearensis Hobber is listed as vulnerable to extinction. It was concluded that this area can be floristically classified as Cerrado, which points to a key area for conservation.

Este trabalho avaliou a seletividade de herbicidas sobre espécies nativas de florestas estacionais semideciduais de São Paulo, amplamente utilizadas em projetos de restauração de ecossistemas naturais degradados: Acacia polyphylla e Enterolobium contortisiliquum (Fabaceae), e Ceiba speciosa e Luehea divaricata (Malvaceae). Os tratamentos consistiram de uma testemunha sem herbicida e da aplicação de herbicidas imazapyr (125, 250, 500, 1.000, 2.000 e 3.000 g ha-1), sulfentrazone (100, 200, 400, 800, 1.400 e 2.400 g ha-1), glyphosate (90, 180, 360, 720, 1.440 e 2.160 g ha-1) e metribuzin (360, 720, 1.920, 2.880, 5.760 e 8.400 g ha-1 ). Foram avaliados os sintomas de fitotoxicidade aos 30 dias após aplicação (DAA) e a biomassa seca da parte aérea. O delineamento experimental foi inteiramente casualizado, com quatro repetições por tratamento. Cada parcela experimental foi constituída de uma muda com 30 cm de altura. Os resultados permitem concluir que, entre os herbicidas testados, o glyphosate foi o menos seletivo às espécies arbóreas, razão pela qual são sugeridas aplicações dirigidas desse produto. As espécies estudadas diferiram em relação à seletividade dos herbicidas avaliados. Para C. speciosa, o imazapyr foi o herbicida mais seletivo, seguido do sulfentrazone. O herbicida metribuzin foi seletivo para A. polyphylla. Quanto a E. contortisiliquum, o metribuzin foi menos tóxico, seguido pelo sulfentrazone. Para L. divaricata, somente o herbicida sulfentrazone foi seletivo.

The present study is the first confirmation of the presence of shoot sprouts on roots in tree species of the Brazilian tropical forest, as these underground systems are usually only analysed by external gross morphological observations. The shoot-bearing roots of seven species, collected in a forest block frequently affected by fire, were sectioned and analysed for the number of primary xylem ridges, stele type and reserve compounds. Starch was the predominant reserve compound and occurred in different quantities among the species. The epicormic shoot buds, which arise spontaneously on root cuttings or plants subjected to fire, were analysed in two of the studied species. These buds showed different sites of origin but were considered epicormic (reparative) since they did not carry bud traces along the secondary xylem during their early development. Shoot bud formation on root systems is generally associated with disturbed environments, and confirmation that sprouting from roots does occur may modify many aspects of our appreciation of the community dynamics of forest species and models that define how we manage and rehabilitate Brazilian forest fragments.

Seasonal semideciduous forests in southeastern Brazil have experienced intensive fragmentation, and the interference of weeds may affect the dynamics of restored communities. The purpose of this study was to determine if there were specific densities of the weeds Urochloa decumbens and Ipomoea grandifolia at which the growth of seedlings of four Neotropical tree species -Senegalia polyphylla and Enterolobium contortisiliquum (Fabaceae) and Ceiba speciosa and Luehea divaricata (Malvaceae) -would be negatively affected. A randomized experimental design was conducted in a greenhouse, with five treatments to each tree species (different weed densities per pot per tree species) and four replicates per treatment. After the weeds flowered, the height and stem diameter of seedlings were quantified, including the aboveground dry biomass and the percentages of macro and micronutrients contents in the leaves. The growth of the tree seedlings was affected by the lowest weed density (two weeds per pot) when interacting with U. decumbens or I. grandifolia. In general, significant decreases in the percentage of macro and micronutrients in the leaves were observed, especially at eight weeds/pot. Such results could warrant experimental practices in chemical control in conjunction with alternative methods to control of these two weeds in restored areas.Interferência de plantas daninhas em mudas de quatro espécies arbóreas neotropicais RESUMO. As florestas estacionais semideciduais do sudeste do Brasil têm experimentado intensa fragmentação e a interferência de plantas daninhas influencia a dinâmica das comunidades restauradas. O objetivo deste estudo foi testar se o aumento das densidades de plantas daninhas (Urochloa decumbens e Ipomoea grandifolia) afetava o crescimento de mudas de quatro espécies de árvores neotropicais -Senegalia polyphylla e Enterolobium contortisiliquum (Fabaceae), Ceiba speciosa e Luehea divaricata (Malvaceae). O delineamento experimental foi inteiramente casualizado: cinco tratamentos por espécie (diferentes densidades de plantas daninhas por vaso, por espécie de árvore) e quatro repetições por tratamento. Após o florescimento das plantas daninhas, quantificaram-se a altura, o diâmetro do caule, a biomassa aérea seca e as porcentagens de conteúdo de macro e micronutrientes nas folhas das espécies arbóreas. Verificou-se que a menor densidade de U. decumbens e de I. grandifolia afetou de negativamente, o crescimento das mudas das espécies nativas. No geral, observou-se diminuição do conteúdo de macro e micronutrientes nas folhas das mudas das quatro espécies arbóreas, principalmente na densidade de oito plantas daninhas/vaso. Os resultados obtidos podem embasar práticas experimentais sobre o controle químico em conjunto com métodos alternativos no controle de I. grandifolia e U. decumbens em áreas de restauração ecológica.Palavras-chave: competição, manejo, floresta estacional semidecidual, restauração.