RESUMO -(Diversidade e estrutura de espécies arbóreas em área alagável do município de Londrina, Sul do Brasil). Um levantamento fitossociológico em área alagável do Parque Estadual Mata dos Godoy, Londrina, PR, sul do Brasil (23°27'S e 51º15'W) determinou a diversidade e a estrutura das espécies arbóreas. O levantamento foi realizado em 0,5ha utilizando-se 50 parcelas de 10m×10m, tendo-se como critério de inclusão o perímetro mínimo a altura do peito de 15cm. Para cada espécie foram calculadas a densidade, a freqüência e a dominância. Palavras-chave -áreas alagáveis, classes de tamanho, riqueza de espécies, fitossociologia, sul do Brasil ABSTRACT -(Diversity and structure of a tree species community in flooded area in the municipality of Londrina, Southern Brazil). A phytosociological study was developed in flooded area of the Mata dos Godoy State Park, municipality of Londrina, southern Brazil (23º27'S and 51°15'W) in order to determine the diversity and the structure of tree species. Fifty 10m×10m plots (0,5ha) were used to sample trees with GBH (girth at breast height) ≥ 15,0cm. Density, frequency and dominance parameters were calculated for each species. In this area 912 living and 58 dead individuals were sampled. The living individuals were distributed in 26 families, 49 genera and 64 species. The value of the Shannon's diversity index was 3,44. The families with the highest species number were Leguminosae and Myrtaceae, while Nectandra megapotamica (Spreng.) Mez, Chrysophyllum

RESUMO -(Tolerância à inundação de Cecropia pachystachya Trec. (Cecropiaceae): aspectos ecofisiológicos e morfoanatômicos).Visando elucidar aspectos da tolerância à hipoxia, plantas de Cecropia pachystachya foram submetidas a 30 dias de inundação. O crescimento e desenvolvimento, a condutância estomática, a fotossíntese e a morfo-anatomia foram avaliadas. A taxa de crescimento relativo (TCR) da raiz e do caule foi inferior em plantas alagadas, não havendo diferenças nesta taxa para as folhas e para a planta inteira. A não variação na TCR das folhas pode ter sido em função da maior esclerofilia foliar das plantas alagadas, que apresentaram menor área. A condutância estomática e a taxa fotossintética diminuíram nas plantas submetidas ao alagamento. Foram observadas alterações morfoanatômicas em caules e principalmente em raízes de plantas alagadas. A análise dos resultados indica que a tolerância desta espécie a períodos de inundação está relacionada à sua capacidade de manter uma satisfatória produção energética. A manutenção de um balanço energético positivo possibilita que mesmo sob estresse, com queda na taxa fotossintética, as plantas desta espécie apresentem uma considerável TCR. Portanto, C. pachystachya pode ser forte competidora em áreas sujeitas ao alagamento. Palavras-chave: alagamento, anatomia ecológica, Cecropia pachystachya, fotossíntese, TCRABSTRACT -(Flood tolerance in Cecropia pachystachya Trec. (Cecropiaceae): ecophysiological and morpho-anatomical aspects). To elucidate certain aspects of hypoxia tolerance in Cecropia pachystachya, plants were submitted to 30 days of flooding. Growth and development, stomatal conductance, photosynthetic rates and morpho-anatomy were studied. Root and stem relative growth rates (RGR) were lower in flooded plants. There was no difference in leaf RGR and whole plant RGR. The maintenance of leaf RGR is possibly related to greater sclerophylly in flooded plants. Stomatal conductance and photosynthetic rate decreased due to flooding. Stems and roots, especially the latter, showed morpho-anatomical alterations in flooded plants. The results so far suggest that flood tolerance in C. pachystachya is related to the capacity to maintain satisfactory energy production. The maintenance of a positive energy balance allows this species to maintain a substantial RGR, even under stress with a lower photosynthetic rate. Therefore C. pachystachya may be a strong competitor in flooded areas.

This study was developed in the Mata dos Godoy State Park (23°27'S, 51°15'W) South

Em matas ciliares da Bacia Hidrográfica do Rio Tibagi, nas áreas sujeitas a inundações periódicas, é comum a ocorrência de S. commersoniana onde, geralmente, se torna a espécie dominante. A fim de elucidar alguns aspectos de tolerância ao alagamento, plantas dessa espécie foram mantidas na capacidade de campo e em solo alagado por dois meses. Após esse período, algumas plantas foram desalagadas para verificar o comportamento da espécie no período de reaeração. O alagamento induziu, em raízes, aumento de espaços intercelulares, redução na espessura do cilindro central e aumento na espessura do córtex. Plantas alagadas cresceram menos que as controle e desenvolveram lenticelas hipertróficas caulinares e algumas raízes adventícias. Plantas reaeradas retomaram o crescimento. Se considerarmos os resultados obtidos, juntamente com aqueles da literatura, tanto de florística e fitossociologia como de bioquímica, pode-se sugerir que as modificações morfoanatômicas observadas são importantes para explicar a tolerância dessa espécie à inundação.
In the woods along the Tibagi River hydrographical basin, in areas subject to periodical flooding, the incidence of S. commersoniana is usual, it often becoming the prevailing species. Plants of this species were kept in well drained and flooded soils for two months, in order to explain some aspects of tolerance to waterlogging. After this period, some plants were returned to the well drained soil in order to check the species behaviour in the re-aeration period. In the roots, flooding induced, an increase of intercellular spaces as well as a thickening of the cortex, and a reduction in the thickeness of the central cylinder. Flooded plants grew less than the control ones, and developed hypertrophic lenticels and some adventitious roots. The re-aired plants recovered in growth. It can be suggested that the morphoanatomical modifications observed are important to explain the tolerance of this species to flooding, if we take into consideration the obtained results, together with those obtained in the literature about floristic and phytosociology, as well as in that dealing with biochemistry

ABSTRACT(Litter production and nutrient cycling in a reforested area and a seasonal semideciduous forest in southern Brazil). Th e aim of this study was to evaluate litter production, N, P, K, Ca and Mg content, nutrient transfer, and litter decomposition rate of a seasonal semideciduous forest and an adjacent reforested area. Th e study was carried out in Godoy Forest State Park (GFST), Paraná state, Brazil. Estimated annual litter production was 8,212 kg.ha -1 .year -1 in the forest and 5,341 kg.ha -1 .year -1 in the reforested area. Th e forest presented higher deposition in post-drought months (September and October). In both areas nutrient concentration (g.kg -1 ) followed the same order in forest -Ca(31.85) > N(19.94) > K(7.14) > Mg(2.28) > P(0.217), and reforested area -Ca(23.02) > N(19.62) > K(7.67) > Mg(1.74) > P(0.302). Nutrient transfer varied more during the year and the decomposition rate was lower in the reforested area. Acta Botanica Brasilica 25(1): 53-57. 2011.

No abstract

Morphological, anatomical and ecophysiological modifications caused by flooding in the growth and development of Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae) were studied and correlated with tolerance to the excess of water in the soil. Three-month-old plants, grown in a greenhouse, underwent a period of 56 days of flooding and a post-flooding period. Photosynthesis rate and growth decreased in T. avellanedae when flooding duration increased. Though not much tolerant, plant adapted itself to short flooding periods. This relative tolerance was probably due to the capacity of T. avellanedae in developing structures which lessened flooding effects and promoted internal diffusion of oxygen from the aerial part to the roots, such as stem fissures, superficial roots and hypertrophied lenticels in the roots. As there was no great variation in the internal anatomy of T. avellanedae leaves and roots, metabolic alterations might have helped in the survival of the species during flooding.

Polymeric nanoparticles have emerged as carrier systems for molecules that release nitric oxide (NO), a free radical involved in plant stress responses. However, to date, nanoencapsulated NO donors have not been applied to plants under realistic field conditions. Here, we verified the effects of free and nanoencapsulated NO donor, S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), on growth, physiological and biochemical parameters of neotropical tree seedlings kept under full sunlight in the nursery for acclimation. S-nitroso-MSA incorporation into chitosan nanoparticles partially protected the NO donor from thermal and photochemical degradation. The application of nanoencapsulated S-nitroso-MSA in the substrate favoured the growth of seedlings of Heliocarpus popayanensis, a shade-intolerant tree. In contrast, free S-nitroso-MSA or nanoparticles containing non-nitrosated mercaptosuccinic acid reduced photosynthesis and seedling growth. Seedlings of Cariniana estrellensis, a shade-tolerant tree, did not have their photosynthesis and growth affected by any formulations, despite the increase of foliar S-nitrosothiol levels mainly induced by S-nitroso-MSA-loaded nanoparticles. These results suggest that depending on the tree species, nanoencapsulated NO donors can be used to improve seedling acclimation in the nursery.