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Windthrow (i.e., trees broken and uprooted by wind) is a major natural disturbance in Amazon forests. Images from medium-resolution optical satellites combined with extensive field data have allowed researchers to assess patterns of windthrow tree-mortality and to monitor forest recovery over decades of succession in different regions. Although satellites with high spatial-resolution have become available in the last decade, they have not yet been employed for the quantification of windthrow tree-mortality. Here, we address how increasing the spatial resolution of satellites affects plot-to-landscape estimates of windthrow tree-mortality. We combined forest inventory data with Landsat 8 (30 m pixel), Sentinel 2 (10 m), and WorldView 2 (2 m) imagery over an old-growth forest in the Central Amazon that was disturbed by a single windthrow event in November 2015. Remote sensing estimates of windthrow tree-mortality were produced from Spectral Mixture Analysis and evaluated with forest inventory data (i.e., ground true) by using Generalized Linear Models. Field measured windthrow tree-mortality (3 transects and 30 subplots) crossing the entire disturbance gradient was 26.9 ± 11.1% (mean ± 95% CI). Although the three satellites produced reliable and statistically similar estimates (from 26.5% to 30.3%, p < 0.001), Landsat 8 had the most accurate results and efficiently captured field-observed variations in windthrow tree-mortality across the entire gradient of disturbance (Sentinel 2 and WorldView 2 produced the second and third best results, respectively). As expected, mean-associated uncertainties decreased systematically with increasing spatial resolution (i.e., from Landsat 8 to Sentinel 2 and WorldView 2). However, the overall quality of model fits showed the opposite pattern. We suggest that this reflects the influence of a relatively minor disturbance, such as defoliation and crown damage, and the fast growth of natural regeneration, which were not measured in the field nor can be captured by coarser resolution imagery. Our results validate the reliability of Landsat imagery for assessing plot-to-landscape patterns of windthrow tree-mortality in dense and heterogeneous tropical forests. Satellites with high spatial resolution can improve estimates of windthrow severity by allowing the quantification of crown damage and mortality of lower canopy and understory trees. However, this requires the validation of remote sensing metrics using field data at compatible scales.

Brazil has a vast reserve of natural forests that belong to the state; hence, the state is responsible for supplying native wood to the market. However, the management in public forests has only begun recently; thus, much research is needed to know about its profitability. This study analyzed the financial feasibility of public forest management by addressing the following aspects: state concession, federal concession, and community forest management. We used the Net Present Value, Annual Equivalent Value, and Average Cost of Production methods to assess financial feasibility and applied the Monte Carlo simulation to estimate the probability of occurrence of NPV values. Community forest management showed profitability and a low occurrence of positive NPV values. The initial subsidies and the absence of royalty payments contributed to their good financial performance. The state and federal forest concessions showed financial unfeasibility and a low probability of profitability, which were justified by a low harvested volume of forest management, a high number of hollow individuals with small dimensions, poor volume estimates, and a high occurrence of species with low commercial values. Financial viability is a critical aspect of public forest management, and the achievement of good results depends on the consideration of several factors and aspects of public forests. Characteristics such as species composition, the distance between the managed areas, and the place of consumption must be considered. Areas that are not financially viable in the current period can be considered for future management and maintenance.

Amazon forests account for ~25% of global land biomass and tropical tree species. In these forests, windthrows (i.e., snapped and uprooted trees) are a major natural disturbance, but the rates and mechanisms of recovery are not known. To provide a predictive framework for understanding the effects of windthrows on forest structure and functional composition (DBH ≥10 cm), we quantified biomass recovery as a function of windthrow severity (i.e., fraction of windthrow tree mortality on Landsat pixels, ranging from 0%-70%) and time since disturbance for terra-firme forests in the Central Amazon. Forest monitoring allowed insights into the processes and mechanisms driving the net biomass change (i.e., increment minus loss) and shifts in functional composition. Windthrown areas recovering for between 4-27 years had biomass stocks as low as 65.2-91.7 Mg/ha or 23%-38% of those in nearby undisturbed forests (~255.6 Mg/ha, all sites). Even low windthrow severities (4%-20% tree mortality) caused decadal changes in biomass stocks and structure. While rates of biomass increment in recovering vegetation were nearly double (6.3 ± 1.4 Mg ha-1  year-1 ) those of undisturbed forests (~3.7 Mg ha-1  year-1 ), biomass loss due to post-windthrow mortality was high (up to -7.5 ± 8.7 Mg ha-1  year-1 , 8.5 years since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40 years. Resprouting trees contributed little to biomass recovery. Instead, light-demanding, low-density genera (e.g., Cecropia, Inga, Miconia, Pourouma, Tachigali, and Tapirira) were favored, resulting in substantial post-windthrow species turnover. Shifts in functional composition demonstrate that windthrows affect the resilience of live tree biomass by favoring soft-wooded species with shorter life spans that are more vulnerable to future disturbances. As the time required for forests to recover biomass is likely similar to the recurrence interval of windthrows triggering succession, windthrows have the potential to control landscape biomass/carbon dynamics and functional composition in Amazon forests.

Amazon forests account for ~25% of global land biomass and tropical tree species. In these forests, windthrows (i.e., snapped and uprooted trees) are a major natural disturbance, but the rates and mechanisms of recovery are not known. To provide a predictive framework for understanding the effects of windthrows on forest structure and functional composition (DBH ≥10 cm), we quantified biomass recovery as a function of windthrow severity (i.e., fraction of windthrow tree mortality on Landsat pixels, ranging from 0%-70%) and time since disturbance for terra-firme forests in the Central Amazon. Forest monitoring allowed insights into the processes and mechanisms driving the net biomass change (i.e., increment minus loss) and shifts in functional composition. Windthrown areas recovering for between 4-27 years had biomass stocks as low as 65.2-91.7 Mg/ha or 23%-38% of those in nearby undisturbed forests (~255.6 Mg/ha, all sites). Even low windthrow severities (4%-20% tree mortality) caused decadal changes in biomass stocks and structure. While rates of biomass increment in recovering vegetation were nearly double (6.3 ± 1.4 Mg ha- 1  year- 1 ) those of undisturbed forests (~3.7 Mg ha- 1  year- 1 ), biomass loss due to post-windthrow mortality was high (up to -7.5 ± 8.7 Mg ha- 1  year- 1 , 8.5 years since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40 years. Resprouting trees contributed little to biomass recovery. Instead, light-demanding, low-density genera (e.g., Cecropia, Inga, Miconia, Pourouma, Tachigali, and Tapirira) were favored, resulting in substantial post-windthrow species turnover. Shifts in functional composition demonstrate that windthrows affect the resilience of live tree biomass by favoring soft-wooded species with shorter life spans that are more vulnerable to future disturbances. As the time required for forests to recover biomass is likely similar to the recurrence interval of windthrows triggering succession, windthrows have the potential to control landscape biomass/carbon dynamics and functional composition in Amazon forests.

The identification of tree species in the field is often a subjective process and misidentifications cause many problems for forest management in the Amazon Forest. Near infrared spectra from dried leaves of herbarium specimens are able to distinguish species in tropical forests. However, toolsto improve species identification directly in the field are needed. In this study, we tested whether spectral reflectance of bark tissues (rhytidome and phloem) collected with a portable spectrometer in the field can be used for the discrimination of tree species. Spectral data was collected for 254 trees of 8 families, 10 genera and 11 species from terra firme forests in Central Amazon with an ASD field spectrometer. Data consisted of reflectance values within 350–2500 nm wavelengths. We compared the rate of correct species recognition for different datasets using linear discriminant models. The rate of correct species assignment using this technique was 98% when using spectra from the inner bark (phloem) and 94% with outer bark (rhytidome) spectra. We suggest that the application of this technique can improve the quality of species identification directly during field inventories, fostering better forest management practices.

The policy of payments for environmental services is implemented in public policies in Brazil, and there are many efforts to increase projects that subsidize rural producers, combining payments with incentives for good agricultural practices that promote these services. Thinking about ways to add these values in projects to restore degraded areas is an opportunity to generate monetary benefits for producers and attractiveness for stakeholders, aiming to increase investments in projects of this nature and gain scale in the restoration of these areas. In this way, this study evaluated the financial viability of a project to implement 16.9 hectares of agroforestry systems in agrarian reform settlements located in the Descoberto HydrographicBasin near Brasília, Federal District, and the proposition of a scenario of payment for environmental services associated with adoption of this agricultural practice by producers. The results were promising for both investors and farmers, as demonstrated by the financial analysis criteria (NPV: USD 63,097.49, IRR: 71%, simple payback: 3 years). The PES scenario was even more attractive, proving to be an encouraging increase for the adoption of this practice by producers.

RESUMO O presente artigo configura-se como um estudo teórico-conceitual que integra duas pesquisas desenvolvidas, respectivamente, em nível de doutorado e de pós-doutorado em Educação. O texto tem por objetivo compreender a inclusão e o letramento digital do idoso, a partir da perspectiva da educação ao longo da vida, fundamentada na acepção humanista do conceito. O exponencial avanço tecnológico e o crescimento da população de pessoas idosas no Brasil e no mundo tornam pungente a necessidade de discutir a inclusão digital dessa faixa etária, bem como a ideia de uma educação que perdure durante todo o processo de viver. A inclusão digital impacta diretamente o pleno exercício da cidadania dos sujeitos sociais contemporâneos, uma vez que as linguagens hipermidiáticas do ciberespaço permeiam várias práticas sociais. Nesse contexto, o artigo propõe uma discussão entre quatro conceitos, a saber: aprendizagem ao longo da vida, inclusão digital, letramento digital e empoderamento (na acepção freiriana do termo). Considera-se que a inclusão digital é uma das facetas da inclusão social do idoso, pelo seu relevante papel na conquista da sua autonomia e do pleno exercício da cidadania. Os conceitos ora apresentados – letramento digital do idoso, aprendizagem ao longo da vida e empoderamento – buscam fornecer argumentos conceituais para melhor compreender as possíveis contribuições da inclusão digital, em uma sociedade marcada pelo fortalecimento das linguagens hipermidiáticas junto às práticas sociais contemporâneas. Palavras-chave: Idoso. Inclusão Digital. Letramento Digital. Educação ao Longa da Vida. Empoderamento. ABSTRACT This article is configured as a theoretical-conceptual study, which integrates two researchers developed at the doctoral and post-doctoral level in Education. The text aims to understand digital literacy from the perspective of lifelong education, based on the humanistic perspective of the concept. The exponential technological advance and the growth of the population of elderly people in Brazil and in the world make the need to discuss the digital inclusion of this age group, as well as the idea of an education that lasts throughout the process of living. Digital inclusion directly impacts the full exercise of citizenship by contemporary social subjects, since the hypermedia languages of cyberspace permeate a lot of social practices. In this context, the article seeks discussion between four concepts: lifelong learning, digital inclusion, digital literacy and empowerment (in the freiriana sense of the term). It is considered that digital inclusion is understood as one of the facets of the social inclusion of the elderly, due to its relevant role, in the achievement of their autonomy and their full exercise of citizenship. The concepts presented here - digital literacy of the elderly, lifelong learning and empowerment - seek to provide conceptual arguments to better understand the possible contributions of digital inclusion, in a society marked by the strengthening of hypermedia languages along with contemporary social practices. Keywords: Elderly. Digital inclusion. Digital Literacy. Lifelong Education. Empowerment.

ABSTRACT: This paperexamined the regional concentration of native fuelwood production in Rio Grande do Norte, Brazil, between 1990-2017. Information on native fuelwood was gathered fromforestry activitiescollected by the Brazilian Institute of Geography and Statistics (IBGE). This studyanalyzed the current situation and the spatial distribution of the state’s fuelwood production by quartiles. The following indicators were used to measure market concentration: Gini Coefficient (G), Comprehensive Concentration Index (CCI), Herfindahl-Hirschman Index (HHI) and Concentration Ratio [CR(k)]. In Rio Grande do Norte, there was a -2.76% annual decrease in the production of native fuelwood, from 5,280 x10³ m³ (1990) to 777 x10³ m³ (2017). Classification of the municipalities by quartile revealed that most municipalities had low fuelwood production. The G inferred a very strong to absolute inequality for the municipalities and a weak to null inequality for the mesoregions.The CCI demonstrated no market concentration in the municipalities and a regional concentration in the mesoregions. The HHI corroborated the CCI by affirming the presence of a competitive market for the municipalities and microregions and a concentrated market in the mesoregions.The CR(k) of the four largest municipalities indicated a moderately low concentration. This study concluded that there is a competitive market structure for native fuelwood inthe state of Rio Grande do Norte.

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha-1, mean ±95 % confidence interval) was marginally higher (p = 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg h-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity (r2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.

Old-growth forests are subject to substantial changes in structure and species composition due to the intensification of human activities, gradual climate change and extreme weather events. Trees store ca. 90 % of the total aboveground biomass (AGB) in tropical forests and precise tree biomass estimation models are crucial for management and conservation. In the central Amazon, predicting AGB at large spatial scales is a challenging task due to the heterogeneity of successional stages, high tree species diversity and inherent variations in tree allometry and architecture. We parameterized generic AGB estimation models applicable across species and a wide range of structural and compositional variation related to species sorting into height layers as well as frequent natural disturbances. We used 727 trees (diameter at breast height ≥ 5 cm) from 101 genera and at least 135 species harvested in a contiguous forest near Manaus, Brazil. Sampling from this data set we assembled six scenarios designed to span existing gradients in floristic composition and size distribution in order to select models that best predict AGB at the landscape level across successional gradients. We found that good individual tree model fits do not necessarily translate into reliable predictions of AGB at the landscape level. When predicting AGB (dry mass) over scenarios using our different models and an available pantropical model, we observed systematic biases ranging from -31 % (pantropical) to +39 %, with root-mean-square error (RMSE) values of up to 130 Mg ha-1 (pantropical). Our first and second best models had both low mean biases (0.8 and 3.9 %, respectively) and RMSE (9.4 and 18.6 Mg ha-1) when applied over scenarios. Predicting biomass correctly at the landscape level in hyperdiverse and structurally complex tropical forests, especially allowing good performance at the margins of data availability for model construction/calibration, requires the inclusion of predictors that express inherent variations in species architecture. The model of interest should comprise the floristic composition and size-distribution variability of the target forest, implying that even generic global or pantropical biomass estimation models can lead to strong biases. Reliable biomass assessments for the Amazon basin (i.e., secondary forests) still depend on the collection of allometric data at the local/regional scale and forest inventories including species-specific attributes, which are often unavailable or estimated imprecisely in most regions.

ABSTRACT Faced with the transition in the global energy structure with the shift in consumption of fossil fuels to renewable and clean sources, there has been an increase in the demand for forest biomass for energy purposes, especially wood pellets, and imports have grown in recent years. Therefore, this study analyzed the world concentration of pellet imports from 2012 to 2018. Data on pellet imports were obtained from the Food and Agriculture Organization of the United Nations (FAO), and the following indicators were used to measure the concentration: Concentration Ratio [CR(k)], Hirschman-Herfindal Index (HHI), Theil Entropy Index (E), Gini Inequality Coefficient (G) and the Hall-Tideman Index (HTI). The results showed a growth of 16.67% p.a. of global pellet imports, from 8.76 million tons (t) in 2012 to 22.15 million tons in 2018. The CR(k) indicated very high concentration for countries and high in the subcontinents. The HHI showed a high concentration for continents and subcontinents and a moderate concentration for countries. Entropy and HTI corroborated the analyzes found in the HHI. The G pointed out strong inequality for all territorial levels and showed trends towards a reduction in inequality as of 2015. The reduction in the concentration in the final years of study is related to the expansion and technological diffusion of energy conversion of the densified biomass, which makes this fuel more affordable.

Resumo: O agronegócio de flores e plantas ornamentais está se consolidando no Brasil. O perfil do produtor brasileiro é de pequeno porte e caracterizado como agricultura familiar. A produção de flores e plantas ornamentais tem um papel importante na economia, gerando empregos e distribuindo melhor a renda. No Distrito Federal a produção de floricultura é realizada pelo pequeno produtor e por sua família, tornando-a assim agricultura familiar. Esta pesquisa tem caráter exploratório e descritivo e foi realizada com o auxílio de um questionário misto para descrever e avaliar o perfil socioeconômico do produtor de flores e plantas ornamentais do Distrito Federal. A análise dos dados foi realizada pela análise estatística bidimensional para testar e validar os resultados obtidos. Os resultados em relação ao sexo dos produtores de flores e plantas ornamentais foram: homens (24,34%) com pelo menos 2 membros da família (16,98%), e para a produção de mudas, as mulheres (16,98%), com mais de 2 membros da família (13,21%). O estado civil dos produtores de flores divide-se em casados (58,82%) e solteiros (23,33%). Concluiu-se que o perfil socioeconômico do produtor de flores e plantas ornamentais é de caráter misto, agricultura familiar, sinais de amadorismo e não possui renda exclusivamente advinda da produção.

Canopy gaps created by wind-throw events, or blowdowns, create a complex mosaic of forest patches varying in disturbance intensity and recovery in the Central Amazon. Using field and remote sensing data, we investigated the short-term (four-year) effects of large (>2000 m(2)) blowdown gaps created during a single storm event in January 2005 near Manaus, Brazil, to study (i) how forest structure and composition vary with disturbance gradients and (ii) whether tree diversity is promoted by niche differentiation related to wind-throw events at the landscape scale. In the forest area affected by the blowdown, tree mortality ranged from 0 to 70%, and was highest on plateaus and slopes. Less impacted areas in the region affected by the blowdown had overlapping characteristics with a nearby unaffected forest in tree density (583 ± 46 trees ha(-1)) (mean ± 99% Confidence Interval) and basal area (26.7 ± 2.4 m(2) ha(-1)). Highly impacted areas had tree density and basal area as low as 120 trees ha(-1) and 14.9 m(2) ha(-1), respectively. In general, these structural measures correlated negatively with an index of tree mortality intensity derived from satellite imagery. Four years after the blowdown event, differences in size-distribution, fraction of resprouters, floristic composition and species diversity still correlated with disturbance measures such as tree mortality and gap size. Our results suggest that the gradients of wind disturbance intensity encompassed in large blowdown gaps (>2000 m(2)) promote tree diversity. Specialists for particular disturbance intensities existed along the entire gradient. The existence of species or genera taking an intermediate position between undisturbed and gap specialists led to a peak of rarefied richness and diversity at intermediate disturbance levels. A diverse set of species differing widely in requirements and recruitment strategies forms the initial post-disturbance cohort, thus lending a high resilience towards wind disturbances at the community level.

O presente artigo caracteriza-se como um estudo teórico-conceitual que procura promover aproximações entre os campos de estudos do letramento, da inclusão digital e da educação de jovens e adultos (EJA). O artigo propõe-se a verificar possibilidades e limites de se adotar uma perspectiva decolonial para a reflexão sobre o letramento digital na educação de jovens e adultos. Os conceitos de inclusão digital, letramento e EJA são compreendidos, cada um em seu campo, sob o enfoque crítico. A EJA em uma perspectiva não compensatória, a inclusão digital em uma perspectiva não instrumental e o letramento a partir do modelo ideológico. O intertexto entre os diferentes campos permitiu concluir que são profícuas as possibilidades de compreensão dos três campos sob o enfoque decolonial e que estudos de caso podem contribuir para verificar empiricamente o potencial transgressor da perspectiva decolonial na inclusão e letramento digital na EJA.

O presente artigo tem como objetivo investigar como se corporifica a produção do conhecimento sobre o judô no Brasil. De abordagem quantitativa do tipo exploratória descritiva, buscou na base de dados da Scielo, Lilacs, Biremee no catálogo de dissertações e teses da Capes todos os estudos com o termo “judô” no título, resumo, assunto e palavras-chaves. Foram lidos os resumos e posteriormente realizada a categorização dos artigos em quatro eixos temáticos, tal como as dissertações e em três eixos as teses. Coletou-se 201 artigos, 112 dissertações e 31 teses, depois de feita a análise dos resumos e o descarte de algumas obras de acordo aos critérios de exclusão adotados, o eixo temático com maior número de estudos nos artigos e dissertações foi o de treinamento, nas teses o eixo sócio-histórico-cultural concentrou a maior parte dos trabalhos, e as publicações na temática educacional foram as de menor número. Deste modo, conclui-se que existe uma predominância da área dee treinamento na produção do conhecimento sobre o judô no Brasil e, apesar do valor educacional atribuído à esta modalidade esportiva, os estudos nesta dimensão são reduzidos.

ABSTRACT This paper analyzed the disparity in the gross production value of timber products from the state of Paraíba, Brazil, between 1994 and 2017. The indicators used were: the locational quotient (Lq), the coefficient of location (Cl), the coefficient of redistribution (Cred), the coefficient of geographic association (Cga), the coefficient of specialization (Cs) and the coefficient of restructuring (Cr). The results obtained indicated that wood was the main timber product extracted in the state of Paraíba, with the Sertão paraibano region being of greater relevance, increasing the disparity between the regions; the Cred pointed out greater change for charcoal extraction; the Mata Paraibana region was the most specialized region, especially for wood extraction; and the Borborema region presented the greatest restructuring in all studied periods. The study evidenced that the extraction of wood products mainly occurred in the more arid regions of the state with the purpose of population subsistence or industrial use, especially in the red ceramics and plaster segments for which wood can be used to generate heat and thermoelectric power.

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We developed an individual-based stochastic-empirical model to simulate the carbon dynamics of live and dead trees in a Central Amazon forest near Manaus, Brazil. The model is based on analyses of extensive field studies carried out on permanent forest inventory plots, and syntheses of published studies. New analyses included: (1) growth suppression of small trees, (2) maximum size (trunk base diameter) for 220 tree species, (3) the relationship between growth rate and wood density, and (4) the growth response of surviving trees to catastrophic mortality (from logging). The model simulates a forest inventory plot, and tracks recruitment, growth, and mortality of live trees, decomposition of dead trees (coarse litter), and how these processes vary with changing environmental conditions. Model predictions were tested against aggregated field data, and also compared with independent measurements including maximum tree age and coarse litter standing stocks. Spatial analyses demonstrated that a plot size of approximately 10 ha was required to accurately measure wood (live and dead) carbon balance. With the model accurately predicting relevant pools and fluxes, a number of model experiments were performed to predict forest carbon balance response to perturbations including: (1) increased productivity due to CO2 fertilization, (2) a single semi-catastrophic (10%) mortality event, (3) increased recruitment and mortality (turnover) rates, and (4) the combined effects of increased turnover, increased tree growth rates, and decreased mean wood density of new recruits. Results demonstrated that carbon accumulation over the past few decades observed on tropical forest inventory plots (approximately 0.5 Mg C ha(-1) year(-1)) is not likely caused by CO2 fertilization. A maximum 25% increase in woody tissue productivity with a doubling of atmospheric CO2 only resulted in an accumulation rate of 0.05 Mg C ha(-1) year(-1) for the period 1980-2020 for a Central Amazon forest, or an order of magnitude less than observed on the inventory plots. In contrast, model parameterization based on extensive data from a logging experiment demonstrated a rapid increase in tree growth following disturbance, which could be misinterpreted as carbon sequestration if changes in coarse litter stocks were not considered. Combined results demonstrated that predictions of changes in forest carbon balance during the twenty-first century are highly dependent on assumptions of tree response to various perturbations, and underscores the importance of a close coupling of model and field investigations.

Living trees constitute one of the major stocks of carbon in tropical forests. A better understanding of variations in the dynamics and structure of tropical forests is necessary for predicting the potential for these ecosystems to lose or store carbon, and for understanding how they recover from disturbance. Amazonian tropical forests occur over a vast area that encompasses differences in topography, climate, and geologic substrate. We observed large differences in forest structure, biomass, and tree growth rates in permanent plots situated in the eastern (near Santarém, Pará), central (near Manaus, Amazonas) and southwestern (near Rio Branco, Acre) Amazon, which differed in dry season length, as well as other factors. Forests at the two sites experiencing longer dry seasons, near Rio Branco and Santarém, had lower stem frequencies (460 and 466 ha(-1) respectively), less biodiversity (Shannon-Wiener diversity index), and smaller aboveground C stocks (140.6 and 122.1 Mg C ha(-1)) than the Manaus site (626 trees ha(-1), 180.1 Mg C ha(-1)), which had less seasonal variation in rainfall. The forests experiencing longer dry seasons also stored a greater proportion of the total biomass in trees with >50 cm diameter (41-45 vs 30% in Manaus). Rates of annual addition of C to living trees calculated from monthly dendrometer band measurements were 1.9 (Manaus), 2.8 (Santarém), and 2.6 (Rio Branco) Mg C ha(-1) year(-1). At all sites, trees in the 10-30 cm diameter class accounted for the highest proportion of annual growth (38, 55 and 56% in Manaus, Rio Branco and Santarém, respectively). Growth showed marked seasonality, with largest stem diameter increment in the wet season and smallest in the dry season, though this may be confounded by seasonal variation in wood water content. Year-to-year variations in C allocated to stem growth ranged from nearly zero in Rio Branco, to 0.8 Mg C ha(-1) year(-1) in Manaus (40% of annual mean) and 0.9 Mg C ha(-1) year(-1) (33% of annual mean) in Santarém, though this variability showed no significant relation with precipitation among years. Initial estimates of the C balance of live wood including recruitment and mortality as well as growth suggests that live wood biomass is at near steady-state in Manaus, but accumulating at about 1.5 Mg C ha(-1) at the other two sites. The causes of C imbalance in living wood pools in Santarém and Rio Branco sites are unknown, but may be related to previous disturbance at these sites. Based on size distribution and growth rate differences in the three sites, we predict that trees in the Manaus forest have greater mean age (approximately 240 years) than those of the other two forests (approximately 140 years).

Understanding how tropical forest carbon balance will respond to global change requires knowledge of individual heterotrophic and autotrophic respiratory sources, together with factors that control respiratory variability. We measured leaf, live wood, and soil respiration, along with additional environmental factors over a 1-yr period in a Central Amazon terra firme forest. Scaling these fluxes to the ecosystem, and combining our data with results from other studies, we estimated an average total ecosystem respiration (Reco) of 7.8 μmol·m−2·s−1. Average estimates (per unit ground area) for leaf, wood, soil, total heterotrophic, and total autotrophic respiration were 2.6, 1.1, 3.2, 5.6, and 2.2 μmol·m−2·s−1, respectively. Comparing autotrophic respiration with net primary production (NPP) estimates indicated that only ∼30% of carbon assimilated in photosynthesis was used to construct new tissues, with the remaining 70% being respired back to the atmosphere as autotrophic respiration. This low ecosystem carbon use efficiency (CUE) differs considerably from the relatively constant CUE of ∼0.5 found for temperate forests. Our Reco estimate was comparable to the above-canopy flux (Fac) from eddy covariance during defined sustained high turbulence conditions (when presumably Fac = Reco) of 8.4 (95% ci = 7.5– 9.4). Multiple regression analysis demonstrated that ∼50% of the nighttime variability in Fac was accounted for by friction velocity (u*, a measure of turbulence) variables. After accounting for u* variability, mean Fac varied significantly with seasonal and daily changes in precipitation. A seasonal increase in precipitation resulted in a decrease in Fac, similar to our soil respiration response to moisture. The effect of daily changes in precipitation was complex: precipitation after a dry period resulted in a large increase in Fac, whereas additional precipitation after a rainy period had little effect. This response was similar to that of surface litter (coarse and fine), where respiration is greatly reduced when moisture is limiting, but increases markedly and quickly saturates with an increase in moisture.

Stable and radiocarbon isotopes were used to investigate the role of soil clay content in the storage and dynamics of soil carbon in tropical forest soils. Organic matter in clay-rich Oxisols and Ultisols contains at least two distinct components: (1) material with light δ13C signatures and turnover times of decades or less; and (2) clay-associated, 13C-enriched, carbon with turnover times of decades at the surface to millennia at depths >20 cm. Soil texture, in this case clay content, exerts a major control on the amount of slowly cycling carbon and therefore influences the storage and dynamics of carbon in tropical forest soils. Soils in primary tropical forest have been proposed as a potentially large sink for anthropogenic carbon. Comparison of carbon stocks in Oxisols sampled near Manaus, Brazil, shows no measurable change in organic carbon stocks over the past 20 years. Simple models estimating the response of soil carbon pools to a sustained 0.5% yr−1 increase in productivity result in C storage rates of 0.09 to 0.13 MgC ha−1 yr−1 in soil organic matter, with additional potential storage of 0.18 to 0.27 MgC ha−1 yr−1 in surface litter and roots. Most storage occurs in organic matter pools with turnover times less than a decade. Export of carbon in dissolved form from upland terra firme Oxisols likely accounts for

ABSTRACT Charcoal has an economic, social and environmental importance, because in addition to being a source of energy, it generates employment and income in the rural environment. Therefore, knowing your market is fundamental for the decision-making of those segments that depend on this raw material. This work analyzed the regional concentration of charcoal production in the state of Paraíba, Brazil, from 1994 to 2016. The data used to measure the regional production concentration (in tons) of native Paraíba charcoal were obtained from the Brazilian Institute of Geography and Statistics (IBGE) from 1994 to 2016. The indicators used were the Concentration Ratio [CR(k)], the Herfindahl-Hirschman Index (HHI), Theil's entropy index (E) and the Gini Index (G). The main results show that the mesorregions of Borborema and Sertão Paraibano present concentrations in charcoal production from Paraíba. The CR(k) of the municipalities had a low to moderately low concentration and a moderately high to a high concentration for the microregions; the HHI and E showed deconcentration tendencies from competitive markets; the G showed strong to very strong inequality for the municipalities and microregions on average. It is concluded that the concentration of charcoal production at regional levels is not concentrated, even though it presents a moderate concentration in the partial indices [CR(k)] for the Paraíba microregions.