In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change.

Summary Seasonal dynamics in the vertical distribution of leaf area index (LAI) may impact the seasonality of forest productivity in Amazonian forests. However, until recently, fine‐scale observations critical to revealing ecological mechanisms underlying these changes have been lacking. To investigate fine‐scale variation in leaf area with seasonality and drought we conducted monthly ground‐based LiDAR surveys over 4 yr at an Amazon forest site. We analysed temporal changes in vertically structured LAI along axes of both canopy height and light environments. Upper canopy LAI increased during the dry season, whereas lower canopy LAI decreased. The low canopy decrease was driven by highly illuminated leaves of smaller trees in gaps. By contrast, understory LAI increased concurrently with the upper canopy. Hence, tree phenological strategies were stratified by height and light environments. Trends were amplified during a 2015–2016 severe El Niño drought. Leaf area low in the canopy exhibited behaviour consistent with water limitation. Leaf loss from short trees in high light during drought may be associated with strategies to tolerate limited access to deep soil water and stressful leaf environments. Vertically and environmentally structured phenological processes suggest a critical role of canopy structural heterogeneity in seasonal changes in Amazon ecosystem function.

Litter fall consists of all organic material deposited on the forest floor, being of extremely important for the structure and maintenance of the ecosystem through nutrient cycling. This study aimed to evaluate the production and decomposition of litter fall in a secondary Atlantic forest fragment of secondary Atlantic Forest, at the Guarapiranga Ecological Park, in São Paulo, SP. The litter samples were taken monthly from May 2012 to May 2013. To assess the contribution of litter fall forty collectors were installed randomly within an area of 0.5 ha. The collected material was sent to the laboratory to be dried at 65 °C for 72 hours, being subsequently separated into fractions of leaves, twigs, reproductive parts and miscellaneous, and weighed to obtain the dry biomass. Litterbags were placed and tied close to the collectors to estimate the decomposition rate in order to evaluate the loss of dry biomass at 30, 60, 90, 120 and 150 days. After collection, the material was sent to the laboratory to be dried and weighed again. Total litter fall throughout the year reached 5.7 Mg.ha-1.yr-1 and the major amount of the material was collected from September till March. Leaves had the major contribution for total litter fall (72%), followed by twigs (14%), reproductive parts (11%) and miscellaneous (3%). Reproductive parts had a peak during the wet season. Positive correlation was observed between total litter and precipitation, temperature and radiation (r = 0.66, p<0.05; r = 0.76, p<0.05; r = 0.58, p<0.05, respectively). The multiple regression showed that precipitation and radiation contributed significantly to litter fall production. Decomposition rate was in the interval expected for secondary tropical forest and was correlated to rainfall. It was concluded that this fragment of secondary forest showed a seasonality effect driven mainly by precipitation and radiation, both important components of foliage renewal for the plant community and that decomposition was in an intermediate rate.

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Green areas and ecosystem services are emerging issues in the management of public areas with a view to promoting healthy and sustainable cities. The aim of this study is to establish and test an Index of Ecosystem Services for Green Areas (Índice de Serviços Ecossistêmicos para Áreas Verdes - ISEAV) to evaluate ecosystem services in urban parks as a technical subsidy for the management of urban green areas. The composition of the Index was based on quantitative indicators selected from a bibliographic review. In order to demonstrate the applicability of the Index, two parks of São Paulo city were selected - Buenos Aires Park and José Emérito Brás Park - and also primary and secondary data were used. The results demonstrate the feasibility of the proposition and application of this Index in two parks of São Paulo, where it was possible to obtain a diversified range of ecosystem services considered relevant for the health of the population.

-The present study aimed to analyze the production and decomposition of litterfall in a fragment of secondary Atlantic forest in the region of Ibiúna, SP, from April 2012 to March 2013. The litterfall production was estimated by 30 collectors distributed randomly in an area of 1000 m 2 , where the deposited material was collected every 15 days. The decomposition of litterfall was estimated through the mass loss in the period of study. After collecting, the material was dried in an oven at 65 °C for seven days to achieve a constant weight. The decomposition constant k was obteined according to Shanks and Oslon (1961) and the time for 50% and 95% of decomposition was estimated. It was found a higher litterfall production in October (454.3 kg ha -1 ) and lower production in July (164.9 kg ha -1 ), with a total amount produced of 3.5 Mg ha -1 year -1 . A delay of one month in the precipitation and relative humidity showed great influence in the litter production during the study. The decomposition rate (k) was 3.1 and the time to decompose 50% of the material was estimated in 2 and ½ months and for 95% of the litterfall the time was estimated in 11 and ½ months. The production and decomposition values of this work are within the range found in other sites of secondary tropical forests.Keywords: Decomposition; Tropical forest; Plant-soil interaction.AVALIAÇÃO DA SERAPILHEIRA NUM FRAGMENTO DE FLORESTA SECUNDÁRIA TROPICAL, IBIÚNA, SP, SUDESTE DO BRASIL RESUMO -Este estudo teve como objetivo analisar a produção e decomposição de serapilheira em um fragmento de Mata Atlântica secundária na região de Ibiúna, SP, durante abril de 2012 a março de 2013. A produção de serapilheira foi estimada por meio de 30 coletores distribuídos aleatoriamente em uma área de 1.000 m 2 , onde o material depositado foi coletado quinzenalmente. A decomposição da serapilheira foi estimada por meio da perda de massa no período do estudo. Após a coleta, o material foi seco em forno a 65 °C, durante sete dias, para atingir peso constante. A constante de decomposição (k) foi obtida de acordo com Shanks e Oslon (1961), sendo, em seguida, calculado o tempo para decomposição de 50% e 95% do material. Foi encontrada maior produção de serapilheira em outubro (454,3 kg.ha -1 ) e menor em julho (164,9 kg.ha -1 ), com uma quantidade total produzida de 3,5 Mg.ha -1 .ano -1 . A precipitação com atraso de um mês e a umidade relativa do ar mostraram grande influência na produção de serapilheira durante o estudo. A taxa de decomposição (k) foi de 3,1 e o tempo de decomposição, de 50 e 95% do material, estimado em dois meses e meio e 11 meses e meio, respectivamente. Os valores de produção e decomposição deste trabalho estão dentro da faixa encontrada em outros sítios de florestas tropicais secundárias.