Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change.

Several studies have explored the linkages between phenology and ecosystem productivity across the Amazon basin. However, few studies have focused on flooded forests, which correspond to c.a. 14% of the basin. In this study, we assessed the seasonality of ecosystem productivity (gross primary productivity, GPP) from eddy covariance measurements, environmental drivers and phenological patterns obtained from the field (leaf litter mass) and satellite measurements (enhanced vegetation index (EVI) from the Moderate Resolution Imaging Spectroradiometer/multi-angle implementation correction (MODIS/MAIAC)) in an Amazonian floodplain forest. We found that ecosystem productivity is limited by soil moisture in two different ways. During the flooded period, the excess of water limits GPP (Spearman’s correlation; rho = −0.22), while during non-flooded months, GPP is positively associated with soil moisture (rho = 0.34). However, GPP is maximized when cumulative water deficit (CWD) increases (rho = 0.81), indicating that GPP is dependent on the amount of water available. EVI was positively associated with leaf litter mass (Pearson’s correlation; r = 0.55) and with GPP (r = 0.50), suggesting a coupling between new leaf production and the phenology of photosynthetic capacity, decreasing both at the peak of the flooded period and at the end of the dry season. EVI was able to describe the inter-annual variations on forest responses to environmental drivers, which have changed during an observed El Niño-Southern Oscillation (ENSO) year (2015/2016).

The present study aimed to evaluate the relationship between the physical properties of the soil and relief in areas that are susceptible to landslides in the sub-basin of the Córrego do Yung, a creek in the urban district Três Moinhos of Juiz de Fora, Minas Gerais. Depth measurements of the solum were made at the soil sampling points, and the subsurface material was collected and analyzed for the two factors of particle size and type of horizon. In the laboratory, we determined the hydraulic conductivity, bulk and particle density, and total porosity, macroporosity and microporosity. The values of the physical properties throughout the sub-basin were predicted and mapped. Thematic maps were generated and showed a relation to each other: the clay was related to a higher hydraulic conductivity, higher porosity and lower soil density. In the steeper areas, the greater silt contents were mapped in the deeper layers and indicated the thin thickness of horizon B in these areas. A close relation of the curvature with the soil thickness was detected and was greater in the flat areas with less slope. The geostatistical analysis showed that the range of values for the properties of macroporosity, microporosity and silt was the lowest in the deeper layers, indicating low structural continuity in potentially erodible areas.

Nos últimos anos os desastres naturais tais como os deslizamentos de terra em áreas urbanas e em rodovias têm se intensificado e provocado mortes e grandes prejuízos materiais no Brasil, neste contexto, oobjetivo do trabalho foi analisar a relação entre a ocorrência de deslizamentos em Juiz de Fora e a pluviometria diária do município, bem como a partir da base de dados da Prefeitura/Defesa Civil, analisar a relação dos atributos do terreno do município com a legislação de uso e ocupação do solo, a fim de discutir a restrição de uso quanto à declividade. As variáveis de terreno empregadas neste estudo foram obtidas pelo modelo digital de elevação (MDE), tendo como base uma planta topográfica plani-altimétrica. Foram utilizados os pontos e polígonos de áreas de risco mapeados pela Defesa Civil. Analisou-se as áreas de risco em relação aos atributos do relevo, discutidos com base na lei de uso e ocupação do solo, que define que terrenos com declividade acima de 30% tem uso restrito. Os dados de pluviosidade foram correlacionados com os dias de ocorrência de deslizamentos. Os resultados apontaram a existência de 222 pontos como áreas de risco. Da sobreposição desses pontos com a declividade, obteve-se a relação entre áreas de riscos e relevo. De acordo com a lei municipal, 124 pontos estariam em áreas iguais ou acima de 30% de declividade, totalizando 56% das áreas de risco da região urbana. Apesar de vários bairros apresentarem declividades acima de 30%, as áreas de risco estão relacionadas às ocupações de baixo padrão social. Verificou-se 74% de probabilidade de deslizamento a partir de dados acumulados de chuva de 10 dias, para a precipitação igual ou acima de 150 mm, e 67% de probabilidade de deslizamentos em 15 dias de observações, para chuva igual ou acima de 200 mm. As equações obtidas nas funções lineares podem ser utilizadas pela defesa civil para enviar alerta de deslizamentos.

The present work aimed to analyze the simulations of surface fluxes of sensible and latent heat, and global radiation using the mesoscale atmospheric model (WRF) for the Bananal Island (Tocantins state, Brazil) region during three distinct seasonal periods (flooded, dry, and wet) in 2004. The final analysis of the NCEP global model was used as initial and boundary conditions of the WRF, which horizontal resolution (5 km) and physical parameterizations follow the operational settings used at CPTEC/INPE. The global radiation, the simulated sensible and latent heat fluxes were consistent with the observed data for the daily cycle, where the R2 was higher than 0.8, showing a good correlation between the data. However, the WRF outputs overestimates/underestimates follow a distinct seasonal pattern between global radiation and heat fluxes. There are some hypotheses for this result, such as potential limitations of the model in describing the surface conditions, whether static or dynamic. Future studies may investigate how sensitive the WRF would be when updating surface conditions for scenarios closer to reality, especially the flooded surface situation.