-(Patterns of litter production in a secondary alluvial Atlantic Rain Forest in southern Brazil). Above-ground litter production is one of the most accessible ways to estimate ecosystem productivity, nutrient fl uxes and carbon transfers. Phenological patterns and climatic conditions are still not fully explained well for tropical and subtropical forests under less pronounced dry season and non-seasonal climates, as well as the interaction of these patterns with successional dynamics. Monthly litterfall was estimated for two years in a 9 to 10 year old secondary alluvial Atlantic Rain forest. Total litterfall was higher in the site with more developed vegetation (6.4 ± 1.2 ton ha -1 year -1 ; 95% confi dence interval) as compared to the site with less developed vegetation (3.0 ± 1.0 ton ha -1 year -1 ). The monthly production of 11 litter fractions (eight fractions comprising the leaf litter of the seven main species of the community and other species; reproductive parts, twigs ≤ 2 cm diameter, and miscellaneous material) were correlated with meteorological variables making possible to identify three patterns of deposition. The main pattern, dominated by leaf-exchanging species, consisted of a cycle with the highest litterfall at the beginning of the rainy season, preceding by basically three months the peaks of the annual cycles of rainfall and temperatures. Other two patterns, dominated by brevi-deciduous species, peaked at the end of the rainy season and at the end of the non-rainy season. Tropical and subtropical dry forests that present the highest leaf fall gradually earlier than rain forests (as the studied sites) are possibly related to the start of senescence process. It seems that such process is triggered earlier by a more severe hydric stress, besides other factors linked to a minor physiological activity of plants that result in abscission.Key words -litterfall, meteorological variables, phenology, primary productivity, sucession RESUMO -(Padrões de produção de serapilheira em uma Floresta Ombrófi la Densa aluvial secundária no Sul do Brasil). A produção de serapilheira é uma das variáveis mais acessíveis para se estimar a produtividade primária, fl uxos de nutrientes e transferências de carbono em ecossistemas terrestres. Padrões fenológicos e condições climáticas ainda não estão bem explicados para fl orestas tropicais e subtropicais sob climas com sazonalidade pouco pronunciada, muito menos a interação desses padrões com a dinâmica sucessional. A produção mensal de serapilheira foi estimada durante dois anos em uma Floresta Ombrófi la Densa aluvial durante o nono e décimo ano de regeneração. O sítio com vegetação mais desenvolvida apresentou maior produção de serapilheira (6,4 ton ha -1 ano -1 ), quando comparado com o sítio com vegetação menos desenvolvida (3,0 ton ha -1 ano -1 ). As produções mensais de 11 frações de serapilheira foram correlacionadas com variáveis meteorológicas possibilitando identifi car três padrões de deposição. O padrão principal, dominado por espécies sempre ver...

During forest succession, litterfall nutrient fluxes increase significantly. The higher inputs of organic matter and nutrients through litterfall affects positively soil fertility and the species composition, which are essential components in forest restoration and management programs. In the present study, the input of nutrients to the forest soil via litterfall components was estimated for two sites of different development stages, in an early successional alluvial rain forest in Brazil. Litterfall returned to the soil, in kg/ha, ca. 93 N, 79 Ca, 24 K, 15 Mg, 6 P, 1.7 Mn, 0.94 Fe, 0.18 Zn, 0.09 Cu and 11.2 Al, in the site where trees were more abundant and had higher values of basal area. In the other area, where trees where less abundant and values of basal area were comparatively low, litterfall returned <50% of those amounts to the forest soil, except for Al. The amount of Al that returned to the soil was similar in both areas due to the high contribution of Tibouchina pulchra (82% of Al returned). Comparatively, high proportion of three dominant native tree species (Myrsine coriacea, T. pulchra and Cecropia pachystachya) explained better litter nutrient use efficiency (mainly N and P) in the site with the least advanced successional stage. Although litterfall of these species show lower nutrient concentrations than the other tree species, their nutrient fluxes were high in both sites, indicating a certain independence from soil essential nutrients. Such feature of the native species is very advantageous and should be considered in forest restoration programs.