While attention on logging in the tropics has been increasing, studies on the long-term effects of silviculture on forest dynamics and ecology remain scare and spatially limited. Indeed, most of our knowledge on tropical forests arises from studies carried out in undisturbed tropical forests. This bias is problematic given that logged and disturbed tropical forests are now covering a larger area than the so-called primary forests. A new network of permanent sample plots in logged forests, the Tropical managed Forests Observatory (TmFO), aims to fill this gap by providing unprecedented opportunities to examine long-term data on the resilience of logged tropical forests at regional and global scales. TmFO currently includes 24 experimental sites distributed across three tropical regions, with a total of 490 permanent plots and 921 ha of forest inventories.

RESUMOEste trabalho objetiva avaliar a composição florística e a fitossociologia de espécies arbóreas do parque fenológico da Embrapa Amazônia Ocidental no Distrito Agropecuário da Suframa (DAS), Manaus-AM, a fim de subsidiar seleções futuras de árvores matrizes visando estudos fenológicos e a implantação de áreas de coleta de sementes. Foram alocadas aleatoriamente 20 parcelas de 10m x 50 m ao longo de um transecto, amostrando-se todos os indivíduos com diâmetro a 1,30 m do solo, (DAP) ≥ 20,0 cm. Foram registrados 240 indivíduos, distribuídos em 100 espécies, 70 gêneros e 29 famílias. As famílias de maior importância ecológica são, em ordem decrescente, Lecythidaceae, Sapotaceae, Mimosaceae, Caesalpiniaceae, Chrysobalanaceae, Fabaceae, Humiriaceae, Moraceae, Vochysiaceae e Apocynaceae. Essas famílias contribuem com 67% da riqueza local de espécies e com 75,8% do número de indivíduos, sugerindo que a diversidade vegetal da área está concentrada em poucas famílias. A família Lecythidaceae possui os maiores valores de dap e número de indivíduos, sendo Sapotaceae a que possui a maior riqueza de espécies na área. Floristic composition and phytosociology of tree species in the Phenological Site of the Embrapa Western Amazonia ABSTRACTThis research was carried out to study the floristic composition and phytosociology of tree species in the phenological site of Embrapa Western Amazonia, Suframa Agropecuary District-SAD, Manaus-AM, aiming to help future selection of seed trees, for the establishment of seed collecting areas. Twenty plots of 10m x 50m were studied, along a topographic sequence, where trees with a diameter at breast height (dbh) ≥ 20,0cm were inventoried. A total of 240 trees belonging to 29 families, in 70 genera with 100 species were identified. The most important families, in a decreasing order, were: Lecythidaceae, Sapotaceae, Mimosaceae, Caesalpiniaceae, Chrysobalanaceae, Fabaceae, Humiriaceae, Moraceae, Vochysiaceae and Apocynaceae. These families constituted 67% of the local species richness and 75,8% of the number of individuals, suggesting that diversity is concentrated in a few families. Lecythidaceae had the largest dbh and number of individuals, and Sapotaceae the greatest richness species in the area. The most important species (IVIs) were Eschweilera coriacea (DC.) S.A. Mori; Qualea paraensis Ducke; Vantanea macrocarpa Ducke; Eschweilera atropetiolata S.A. Mori; Couratari stellata A.C. Sm.; Lecythis usidata Miers.; Eperua duckeana R.S. Cowan; Eschweilera amazonica R. Knuth and Chrysophyllum manaosense (Aubr.) T.D. Penn. The Shannon diversity and Sorensen similarity indexes indicated a low diversity and a high dissimilarity floristic among plots in this study for the minimum dbh considered. The diameter of the first class measuring 20cm -30cm presented the most number of individuals, contributing 45% of samples. Above the center class of 55cm of dbh, around 90% of species have been represented by only one.

RESUMOEste trabalho analisou dados de três inventários florestais realizados na área da Floresta Experimental, pertencente à Embrapa Amazônia Ocidental e localizada no km 54 da BR-174, em Manaus/AM. O objetivo foi estudar a dinâmica da floresta -taxas de incremento, recrutamento e mortalidade -além do estoque de carbono, em uma área de floresta primária, sem qualquer tipo de intervenção. Dynamics and carbon storage in primary forest in the region of Manaus / AM ABSTRACTThis study analyzed data from three forest inventories conducted in the Experimental Forest, which belongs to Embrapa Western Amazon basin and is located at km 54 on BR-174, Manaus / AM. The aim was to study forest dynamics -the rates of recruitment, growth and mortality -in addition to carbon storage in an area of primary forest, without any intervention. The surveys were conducted in the years 2005, 2007 and 2010 in 15 permanent plots of 1 hectare each. There, all trees with diameter at breast height (DBH) above 10 cm were measured. We calculated the rates of recruitment and mortality, the periodic annual increments (PAIs) in terms of DBH, basal area and volume, fresh and dry biomass above the soil and total carbon storage in the vegetation. The recruitment rates were 2.0 percent and 1.8 percent, and mortality were 0.

The Brazil nut is considered one of the noblest trees of the Amazon biome and contains social, ecologic and economic importance to this region. The study of the spatial variance of the edaphic properties in native nut trees can direct future researches about more efficient samplings. The Geostatistics is the methodology utilized for this type of study, once that it considers the structural and random characteristics of a variable spatially distributed. This work sought to get a higher knowledge about the distribution of the nutrients in the soil, verifying the relationship with the occurrence of this species, to thereby provide subsidies to future forest management and maintenance/enlargement of the productivity in these areas. The soil samples were collected from 30 × 30 m on the line, in all of the lines in part of the study, totaling 60 samples. All of the points were georeferenced. The preparation of the samples for the sample preparation for the chemical analysis and the methods and calculations to determine the physicochemical variables studied were described by Nogueira and Souza (2005). The statistical and geostatistical analysis were conducted using the R computational environment, version 3.2.2. Most of the studied variables presented defined level. For the physical variables, there was predominance of the adjustment to the model of the gaussian variogram, follower by the spherical model. In the case of the chemical variables, there were two occurrences for each adjustment model (spherical, exponential and gaussian). The variables that best presented spatial relation with the occurrence of Brazil nut trees were the silt, clay, macroporosity, pH, phosphorus, zinc and copper.

-Terra Firme dense forest occurs in 65% of the Amazonian region and is characterized by the high diversity of plant species and high occurrence of rare plant species. The objective of this work was to analyze the horizontal structure of 15 hectares of plots, randomly chosen from a set of 400 ha of permanent plots situated at the Experimental Site of Embrapa, Manaus, Amazonas State, Brazil. All individuals with DBH > 10 cm were identified at the level of species in 2005. The VI values (Values of importance) were separated in classes of range with one (01) standard deviation and the individuals distributed according to DBH classes of 10 cm in amplitude. In total, 8771 individuals were identified, distributed into 264 species and 53 families. A larger number of individuals is concentrated in a few number of species, such as Protium hebetatum D.C. Daly, Eschweilera coriacea (DC.) S.A. Mori and Licania oblongifolia Standl, which sum up 21% of the total number of individuals and 12% of the VI. There is a high occurrence of rare species (36%). The families Sapotaceae, Lecythidaceae and Burseraceae together accounted for 39% of the total number of individuals. The diametric structure in an inverse-J shape shows that 80% of the individuals are concentrated in the DBH classes ranging from 10 to 30 cm. The results highlight the high occurrence of rare species and those with low density, and with distribution restricted to some plots, particularly those belonging to the lowest classes of VI, which deserve special attention in actions for biodiversity conservation and forest management.

Tree species community spatial structure in a terra firme Amazon forest, Brazil Estructura espacial de la comunidad de especies arbóreas en el "terra firme", selva amazónica, Brasil SUMMARYAll trees with diameter at breast height dbh ≥ 10.0 cm were stem-mapped in a "terra firme" tropical rainforest in the Brazilian Amazon, at the EMBRAPA Experimental Site, Manaus, Brazil. Specifically, the relationships of tree species with soil properties were determined by using canonical correspondence analyses based on nine soil variables and 68 tree species. From the canonical correspondence analyses, the species were grouped into two groups: one where species occur mainly in sandy sites, presenting low organic matter content; and another one where species occur mainly in dry and clayey sites. Hence, we used Ripley`s K function to analyze the distribution of species in 32 plots ranging from 2,500 m 2 to 20,000 m 2 to determine whether each group presents some spatial aggregation as a soil variations result. Significant spatial aggregation for the two groups was found only at over 10,000 m 2 sampling units, particularly for those species found in clayey soils and drier environments, where the sampling units investigated seemed to meet the species requirements. Soil variables, mediated by topographic positions had influenced species spatial aggregation, mainly in an intermediate to large distances varied range (≥ 20 m). Based on our findings, we conclude that environmental heterogeneity and 10,000 m 2 minimum sample unit sizes should be considered in forest dynamic studies in order to understand the spatial processes structuring the "terra firme" tropical rainforest in Brazilian Amazon.Key words: canonical correspondence analysis, Ripley`s K, spatial point pattern, Amazon forest, soil nutrients. RESUMENFueron mapeados los árboles con diámetro a la altura del pecho ≥ 10,0 cm en un bosque tropical lluvioso "terra firme" de la amazonía brasileña, en el Sitio Experimental de EMBRAPA, Manaus, Brasil. Las relaciones de 68 especies arbóreas con las propiedades del suelo fueron determinadas mediante análisis de correspondencia canónica sobre la base de nueve variables del suelo. En este análisis, las especies fueron agrupadas en dos grupos: uno, donde estas crecen principalmente en arena, con suelos de bajo contenido de materia orgánica, y otro, con especies que se desarrollan principalmente en suelos secos y arcillosos. La función K de Ripley fue utilizada para analizar la distribución de las especies en 32 parcelas de 2.500 hasta 20.000 m 2 , con el fin de determinar si cada grupo presenta cierto grado de agregación espacial como resultado de variaciones del suelo. Una agregación espacial significativa para los dos grupos solo se encontró en unidades de muestreo > 10.000 m 2 , en particular, para especies en suelos arcillosos y ambientes más secos, en los que las unidades de muestreo parecían cumplir con los requisitos de las especies. Variables del suelo, mediadas por la posición topográfica, influyeron la agregación espacial de ...

Amazon forests are being degraded by myriad anthropogenic disturbances, altering ecosystem and climate function. We analyzed the effects of a range of land‐use and climate‐change disturbances on fine‐scale canopy structure using a large database of profiling canopy lidar collected from disturbed and mature Amazon forest plots. At most of the disturbed sites, surveys were conducted 10–30 years after disturbance, with many exhibiting signs of recovery. Structural impacts differed in magnitude more than in character among disturbance types, producing a gradient of impacts. Structural changes were highly coordinated in a manner consistent across disturbance types, indicating commonalities in regeneration pathways. At the most severely affected site – burned igapó (seasonally flooded forest) – no signs of canopy regeneration were observed, indicating a sustained alteration of microclimates and consequently greater vulnerability to transitioning to a more open‐canopy, savanna‐like state. Notably, disturbances rarely shifted forests beyond the natural background of structural variation within mature plots, highlighting the similarities between anthropogenic and natural disturbance regimes, and indicating a degree of resilience among Amazon forests. Studying diverse disturbance types within an integrated analytical framework builds capacity to predict the risk of degradation‐driven forest transitions.

This research estimated litter production and analyzed its relation to environmental variables such as maximum temperature, insolation, and rainfall. The study was conducted on a 300 × 300 m experiment as part of the project titled mapping of native Brazil nut stands and socio-environmental and economic characterization of Brazil nut production systems (MapCast), in the Tapajós National Forest (FLONA Tapajós). Every 30 days for one full year (August 2015 to July 2016), litterfall was collected and stored in a laboratory. After drying, the material was separated into leaves, wood, flowers and fruits, and miscellaneous and weighed. Statistical tests conducted were Shapiro-Wilk (5%), Principal coordinate analysis, t-test, Pearson's linear correlation, cross-correlation, and canonical redundancy analysis. Rainfall and temperature data were inferior and superior, respectively, to normal climate conditions in the region, and data for solar insolation had an abnormal pattern compared to normal climate conditions. Leaf production varied between 169.9 and 965.6 kg ha . The greatest leaf production was measured during the months with the lowest amount of rainfall and highest temperatures, and variation in leaf production and total litterfall was partially explained by temperature and insolation.