Jonas Eduardo Bianchin

Deposição de Fitomassa em Formações Secundárias na Floresta Atlântica do Paraná

Este trabalho objetivou avaliar a deposicao de serapilheira em tres formacoes secundarias com diferentes idades na Floresta Ombrofila Densa Submontana no Parana. A serapilheira anual produzida foi avaliada mensalmente por 25 coletores (1 m2) distribuidos sistematicamente em cada formacao secundaria (1 ha) e separada em fracoes (ramos, orgaos reprodutivos, miscelânea e folhas). Nao houve diferenca significativa entre as formacoes quanto a deposicao anual de serapilheira, provavelmente devido as semelhancas entre elas com relacao a estrutura da vegetacao e as condicoes meteorologicas. A maior deposicao de serapilheira total e fracoes ocorreu nos meses com maiores temperatura e precipitacao. A fracao folhas foi a mais representativa na serapilheira total em todas as formacoes, sendo que na floresta secundaria menos desenvolvida (FS-1) houve contribuicao de um menor numero de especies, quando comparada com a floresta secundaria intermediaria (FS-2) e a floresta secundaria mais desenvolvida (FS-3).

Litterfall and Nutrient Dynamics in a Mature Atlantic Rainforest in Brazil

We assessed litterfall and nutrient cycling in an old-growth Atlantic rainforest in southern Brazil. Plant litter collected monthly was separated into: leaves, twigs, reproductive organs, and fragments, and dried, weighed, and ground. Determination of carbon, nitrogen, phosphorus, potassium, calcium, magnesium, and sodium contents of different litter fractions was also performed. The total deposition was 8.44 Mg-1 ha-1 year-1, with a higher proportion of leaves fraction. Litterfall predominated in spring and summer, coinciding with the highest average temperature and rainfall in the study area. For leaves, twigs and fragments, the elements sequence of concentration was C>N>Ca>K>Mg>P>Na; whereas for reproductive organs it was C>N>K>Ca>Mg>P>Na. A higher concentration of nutrients was observed in spring and summer for the leaves fraction. The quantitative transfer of nutrients by litterfall fractions to the forest soil followed the same sequence observed for the concentration of nutrients.