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The objective of this study was to assess the quality and potential of wood from naturally fallen trees in the forest for product development and to provide subsidies for the use of raw material. The inventory of fallen trees was carried out along the road from the Experimental Station of Tropical Silviculture of the National Institute for Research in the Amazon (EEST / INPA) - Nucleus ZF-2, at km 23 of the ZF-2 road that starts to the left of km 50 of Highway BR-174 (Manaus-Boa Vista). Only trees that had fall characteristics due to natural factors, that is, that had exposed roots, were considered for the inventory. It was also stipulated as a requirement for measurement the diameter class of trees of 25 cm ≤ DBH ≤ 45 cm. From each naturally fallen tree, the diameters (largest and smallest) and their length were measured. 5cm thick discs were removed from the trees to obtain samples for scientific identification of the wood and determination of physical properties. Based on the inventory, it was identified that many of the trees naturally fallen in the forest are in good conditions of use, considering their woody material and their volume. The Alexa grandiflora species presented the highest volume with 2,788 m³ for a single tree, followed by the species Ormósia sp. with 2,287 m³ and Protium tenuifolium Engl with a volume of 1,269 m³. Regarding the health of the inventoried trees, all from the species Byrsonima crispaJuss. had no sign of degradation, followed by the species Croton lanjouwensis and Ingá sp. The most frequent class was medium density with 9 species with a variation of 0.47g/cm3 to 0.62g /cm3. Eperua schomburgkiana Benth was the most dense with 0.78g /cm3.The levels of degradation found and the intrinsic characteristics of the species did not compromise the possibilities of using this wooden product, and can represent an excellent opportunity for economic return, contributing to minimize the pressures exerted around the living forest.

In the forests of the Amazon Basin, there are still few studies on soil compaction caused by logging activities. This study evaluated an operation located on the property of a timber company in Central Amazonia, which uses harvesting techniques based on the harvesting system developed by the Centre for Agricultural Research in Suriname. The timber-extraction method employed by the timber company consists of three activities: (1) skid trail construction with a track-type tractor, (2) log winching with a winch attached to the tractor, and (3) log skidding with a rubber-tired skidder. Soil bulk density and soil penetration resistance were quantified to 20 cm in depth. After a single tractor ingress and egress for trail construction, the soil incurred an increased root growth-limiting bulk density and penetration resistance. However, log winching did not cause significant soil compaction. The conclusions of the study were: (1) the greatest impact from this harvesting system came from the skid trail construction, (2) the technique of log winching limited forest floor compaction and disturbance that damages forest regeneration, and (3) log skidding during dry soil conditions limited increases in compaction and track formation.

Made available in DSpace on 2021-06-25T10:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The forests of Amazonia are among the most biodiverse plant communities on Earth. Given the immediate threats posed by climate and land-use change, an improved understanding of how this extraordinary biodiversity is spatially organized is urgently required to develop effective conservation strategies. Most Amazonian tree species are extremely rare but a few are common across the region. Indeed, just 227 ‘hyperdominant’ species account for >50% of all individuals >10 cm diameter at 1.3 m in height. Yet, the degree to which the phenomenon of hyperdominance is sensitive to tree size, the extent to which the composition of dominant species changes with size class and how evolutionary history constrains tree hyperdominance, all remain unknown. Here, we use a large floristic dataset to show that, while hyperdominance is a universal phenomenon across forest strata, different species dominate the forest understory, midstory and canopy. We further find that, although species belonging to a range of phylogenetically dispersed lineages have become hyperdominant in small size classes, hyperdominants in large size classes are restricted to a few lineages. Our results demonstrate that it is essential to consider all forest strata to understand regional patterns of dominance and composition in Amazonia. More generally, through the lens of 654 hyperdominant species, we outline a tractable pathway for understanding the functioning of half of Amazonian forests across vertical strata and geographical locations. Institute of Environment Department of Biological Sciences Florida International University School of Geography University of Leeds Center for Global Discovery and Conservation Science Arizona State University Instituto Nacional de Pesquisas da Amazônia (INPA) Ecology and Evolutionary Biology University of Michigan Departamento de Ciencias Forestales Universidad Nacional de Colombia Departamento de Biología Universidad Autónoma de Madrid Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM) Universidad Autónoma de Madrid Naturalis Biodiversity Center Systems Ecology Vrije Universiteit Lancaster Environment Centre Lancaster University Environmental Change Institute University of Oxford Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life Sciences School of Geosciences University of Edinburgh Missouri Botanical Garden Brazilian Agricultural Research Corporation (Embrapa) Universidad Nacional de San Antonio Abad del Cusco Department of Intergrative Biology University of California Berkeley Department of Biology University of Turku Instituto de Investigaciones de la Amazonía Peruana UNELLEZ-Guanare Programa de Ciencias del Agro y el Mar Herbario Universitario (PORT) Compensation International Progress S. A.—Ciprogress Greenlife AMAP Université de Montpellier CIRAD CNRS INRAE IRD Environmental and Rural Science University of New England INRA UMR EcoFoG AgroParisTech CNRS CIRAD Université des Antilles Université de Guyane CIRAD UMR EcoFoG BIOMAS Universidad de Las Américas Instituto de Ecología Herbario Nacional de Bolivia Departamento de Biologia Universidade Federal de Rondônia Laboratoire Evolution et Diversité Biologique (EDB) CNRS/UPS School of Geography Earth and Environmental Sciences University of Plymouth Department of Ecology and Evolutionary Biology Cornell University Department of Geography University of Exeter Facultad de Ciencias Biológicas Universidad Nacional de la Amazonía Peruana Estación Biológica del Jardín Botánico de Missouri Institut de Ciència i Tecnologia Ambientals Universitat Autònoma de Barcelona School of Geography & Sustainable Development University of St Andrews Department of Environment and Development Federal University of Amapá Centre for Tropical Environmental and Sustainability Science (TESS) and College of Marine and Environmental Sciences James Cook University Department of Environmental Science and Policy George Mason University Inventory and Monitoring Program National Park Service Smithsonian Institution Department of Plant Sciences University of Cambridge Living with Lakes Centre Laurentian University DRGB Instituto Nacional de Innovación Agraria (INIA) Herbarium Amazonense (AMAZ) Universidad Nacional de la Amazonia Peruana Department of Ecology Universidade de São Paulo Institute for Biodiversity and Ecosystem Dynamics University of Amsterdam Centro de Estudos da Biodiversidade Universidade Federal de Roraima Museo de Historia Natural Noel Kempff Mercado Universidad Autónoma Gabriel Rene Moreno Faculdade de Ciências Agrárias Biológicas e Sociais Aplicadas Universidad do Estado de Mato Grosso Centro de Biociências Universidade Federal do Rio Grande do Norte Department of Ecology Evolution and Behaviour University of Minnesota Department of Geography University College London Departamento de Ciencias Biológicas Universidad de Los Andes (Colombia) Centro de Ciências Biológicas e da Natureza Universidade Federal do Acre Nicholas School of the Environment Duke University Iwokrama International Centre for Rainforest Conservation and Development Smithsonian’s National Zoo & Conservation Biology Institute Instituto de Ciencias Naturales Universidad Nacional de Colombia Universidade Federal Rural da Amazônia—UFRA/CAPES Museu Paraense Emílio Goeldi Laboratorio de Ecología de Bosques Tropicales y Primatología Fundación Natura Colombia Universidad de Los Andes Facultad de Forestales Universidad Nacional de la Amazonía Peruana Institute of Research for Forestry Development Universidad de los Andes School of Environmental and Forest Sciences (SEFS) University of Washington Universidad Regional Amazónica Ikiam Agteca-Amazonica Universidad Autónoma del Beni Instituto Amazónico de Investigaciones (IMANI) Universidad Nacional de Colombia Broward County Parks and Recreation Biological Sciences Florida Atlantic University-Davie Museu Universitário Universidade Federal do Acre Facultad de Ingeniería Ambiental Universidad Estatal Amazónica Department of Biology Washington University in St Louis National Institute for Space Research (INPE) Geoinformática & Sistemas (GeoIS) School of Earth Sciences and Environmental Sustainability Northern Arizona University Department of Geography and the Environment University of Texas at Austin Instituto de Ciência e Tecnologia São Paulo State University (UNESP) School of Anthropology and Conservation University of Kent Universidade Federal do Amazonas Herbario Alfredo Paredes (QAP) Universidad Central del Ecuador School of Geography Earth and Environmental Sciences University of Birmingham Department of Life Sciences Imperial College London Science and Education The Field Museum Universidad Tecnica del Norte Herbario Nacional del Ecuador Research Institute Alexander von Humboldt Instituto de Ciência e Tecnologia São Paulo State University (UNESP)

Selective logging is one of the most prominent land uses in tropical forests and although it involves harvesting a limited number of trees, the impact on forest structure, composition and aboveground biomass can be significant. Although these impacts are well documented, what is little known is the extent to which selective logging affects tree floristic composition and its recovery process. Understanding how floristic composition is affected by logging activities is essential for determining subsequent cutting cycles, for the maintenance of carbon stocks and for biodiversity conservation. This research investigates the effect of logging on long-term trends on the recovery of species composition in a tropical forest using a unique logging experiment where measurements have been taken annually over a period of 25 years. Changes in 12 long-term 1-hectare (ha) permanent plots were assessed where different selective logging intensities occurred. In the first years after logging, floristic composition differed widely between intact and selectively logged forests, with exploited areas deviating from pre-logged composition. Over time, exploited areas shifted towards the original composition, with more pronounced changes in this trend after ∼13 years. Shifts in floristic composition were caused mainly by a significant increase in light-demanding fast-growing pioneer species and their subsequent continuous high mortality rates after 13 years of the recovery process. In contrast, the control plots showed similar shifts in composition over time, suggesting external factors such as long-term climate changes may be driving these shifts. The results suggest that 25 years after an experimental selective logging has taken place, floristic composition tends to recover closer to the pre-logged status. Thus, in the absence of further human disturbances, experimental selectively logged forests in low to moderate intensities are compatible with biodiversity conservation, at least during the first cycle of exploitation. Reconciling conservation strategies with the recovery of stocks of commercial timber species would be greatly improved by using these results and lead towards more sustainable forest management plans.

The factors shaping the distribution of giant tropical trees are poorly understood, despite its importance as a link between evolutionary biology and ecosystem biogeochemistry. The recent discovery of clusters of trees over 80 metres tall in the Guiana Shield region of the Amazon rainforest challenges the current understanding of the factors controlling the growth and survival of giant trees. The new discovery led us to revisit the question: what determines the distribution of the tallest trees of the Amazon?Here, we used high-resolution airborne LiDAR (Light Detection and Ranging) surveys to measure canopy height across 282,750 ha of primary old-growth and secondary forests throughout the entire Brazilian Amazon to investigate the relationship between the occurrence of giant trees and the environmental factors that influence their growth and survival. Our results suggest that the factors controlling where trees grow extremely tall are distinct from those controlling their longevity. Trees grow taller in areas with high soil clay content (> 42%), lower radiation (< 130 clear days per year) and wind speeds, avoiding alluvial areas (elevations higher than 40 m a.s.l), and with an optimal precipitation range of 1,500 to 2,500 mm yr-1. We then used an envelope model to determine the environmental conditions that support the very tallest trees (i.e. over 70 m height). We found that, as opposed to the myriad of interacting factors that control the maximum height at a large scale, wind speed had by far the largest influence on the distribution of these sentinel trees, and explained 67% of the probability of finding trees over 70 m in the Brazilian Amazon forest.The high-resolution pan-Amazon LiDAR data showed that environmental variables that drive growth in height are fundamentally different from environmental variables that support their survival. While precipitation and temperature seem to have lower importance for their survival than expected from previous studies, changes in wind and radiation regimes could reshape our forested biomes. This should be carefully considered by policy-makers when identifying important hotspots for the conservation of biodiversity in the Amazon.

The Amazon rainforest covers an area of about 50% of the Brazilian national territory, which consists mainly of upland rainforests that are generally poorly managed, because of low investment in technology, planning, operations and manufacturing. Logging activities require a large contingent of heavy machinery and an intense physical workload from the operators and crews. The thermal comfort at work in tropical regions is between 20 and 24°C; however, in the Central Amazon the daily average temperature exceeds 28°C. The sum of these adverse factors leads to a common denominator: low quality logging operations that lead to unsustainable forest management. The objective of this study was to investigate the influence of environmental thermal conditions on performance, rest breaks, work dynamics and safety of workers involved in the logging operations, as well as to understand better their interactions. The data was collected from the following logging activities: felling, pre-skidding, skidding and landing operations. These variables were analyzed using PCA analysis, MANOVA and multiple linear regression. The variables of productivity and rest breaks were strongly influenced by mechanical interruption and time of the workday. We concluded that mechanical availability was the most influential factor in the performance of logging operations. In addition, environmental thermal conditions, bonus payments and work dynamics showed an influence. To a less extent, there was an influence of safety and physical comfort of workers, which resulted in higher rest breaks, depending on the operation involved. This influence was observed in operations with a higher physical workload (felling and pre-skidding). Moreover, the tree volume had a significant impact on the productivity of the chainsaw operator, which was also influenced by the species factor, as in the species Hymenolobium modestum. Lastly, improvements in working conditions such as appropriate clothing, job rotation and scheduled breaks would lead to a greater worker well-being with increased labor productivity and safety. In turn, this would greatly contribute to the quality and performance of overall forest management and sustainability in the economic development of the Amazon region.

Azteca ants are widely distributed in the neotropics and have been utilized as natural insect repellent for centuries. Azteca oils provide natural defense against herbivores in mutualistic interactions between ants and their host trees. While chemical characterization of oil secretions revealed a composition dominated by iridoids and ketones, the volatile emissions from Azteca ants, and therefore the active gas-phase semiochemicals, remain uncharacterized. In this study, we determined the composition of volatile emissions from a sample of an Azteca ant nest near the Rio Negro in the central Amazon. We found Azteca emissions were composed of a blend of methyl cyclopentyl and methyl cyclopentenyl based volatiles previously identified in Azteca oil extracts as potent alarm pheromones. The ketone 6-methyl-5-hepten-2-one, which also waspreviously identified as a major component of the Azteca oil, was found to be the dominant volatile emitted. For the first time, we report emissions of the highly volatile ketones 2,3-butadione and acetoin from the Azteca nest. Our study has important implications for the better understanding of the ecology and defense strategies of Azteca ants in herbivore defense and provides a base for future commercial applications involving Azteca ant essential oils as natural insect repellents.

Author(s): Negron-Juarez, R; Ferreira, SJF; Mota, MC; Faybishenko, B; Monteiro, MTF; Candido, LA; Ribeiro, RP; de Oliveira, RC; de Araujo, AC; Warren, JM; Newman, BD; Gimenez, BO; Varadharajan, C; Agarwal, D; Borma, L; Tomasella, J; Higuchi, N; Chambers, JQ | Abstract: Soil moisture plays a key role in hydrological, biogeochemical, and energy budgets of terrestrial ecosystems. Accurate soil moisture measurements in remote ecosystems such as the Amazon are difficult and limited because of logistical constraints. Time domain reflectometry (TDR) sensors are widely used to monitor soil moisture and require calibration to convert the TDR's dielectric permittivity measurement (Ka) to volumetric water content (θv). In this study, our objectives were to develop a field-based calibration of TDR sensors in an old-growth upland forest in the central Amazon, to evaluate the performance of the calibration, and then to apply the calibration to determine the dynamics of soil moisture content within a 14.2-m-deep vertical soil profile. Depth-specific TDR calibration using local soils in a controlled laboratory setting yielded a novel Ka–θv third-degree polynomial calibration. The sensors were later installed to their specific calibration depth in a 14.2-m pit. The widely used Ka–θv relationship (Topp model) underestimated the site-specific θv by 22–42%, indicating significant error in the model when applied to these well-structured, clay-rich tropical forest soils. The calibrated wet- and dry-season θv data showed a variety of depth and temporal variations highlighting the importance of soil textural differentiation, root uptake depths, as well as event to seasonal precipitation effects. Data such as these are greatly needed for improving our understanding of ecohydrological processes within tropical forests and for improving models of these systems in the face of changing environmental conditions.

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted—modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth–survival trade-off in driving tropical tree mortality., Tree mortality has been shown to be the dominant control on carbon storage in Amazon forests, but little is known of how and why Amazon forest trees die. Here the authors analyse a large Amazon-wide dataset, finding that fast-growing species face greater mortality risk, but that slower-growing individuals within a species are more likely to die, regardless of size.

Growth rings are investigated in trees harvested in the second cutting cycle in southern Amazonia and have important implications for dendrochronological studies and for forest management. In the southern Brazilian Amazon, upland moist forests have been managed based on a polycyclic system, which cutting cycle (CC) varies from 25 to 35 years, and the minimum logging diameter (MLD) is 50 cm for all species. Many forests logged during the 1970s are being prepared for the second cycle. However, without growth and yield rates information on the remaining forests as well as for individual species, the principles of sustainable management will be jeopardized. For species with annual growth rings, such information can be obtained using dendrochronological techniques. This study investigated the periodicity of rings in Qualea paraensis and Parkia pendula in a forest that had already experienced one cutting cycle. This information was used to estimate growth and yield rates, and adjusting to equations to estimate individual species MLD and CC. Dendrochronological techniques were combined with radiocarbon analyses to confirm whether rings were annual. Rings of Q. paraensis were confirmed to be annual without radiocarbon analysis. However, P. pendula rings were poorly distinguishable; therefore, delimitation and ring counting were systematically underestimated by 10%. Growth and yield rates of managed forests were favored by logging. The MLD should be 53 cm for Q. paraensis, and 42 cm for P. pendula; and the CC must be 11 and 17 years, respectively. It is concluded that MLD and CC legally defined by the Brazilian laws are not adequate for the studied species; in addition, the use of radiocarbon-calibrated dendrochronology technique is essential to produce robust and unbiased estimates of growth and yield rates.

The original version of this Article contained an error in Table 2, where the number of individuals in the “All Amazonia” row was reported as 11,6431 instead of 116,431. Also, the original version of this Article contained an error in the Methods, where the R2 for the proportion of broken/uprooted dead trees increase per year was reported as 0.12, the correct value being 0.06. The original version of this Article contained errors in the author affiliations. The affiliation of Gerardo A. Aymard C. with UNELLEZGuanare, Herbario Universitario (PORT), Portuguesa, Venezuela Compensation International Progress S.A. Ciprogress–Greenlife.

A utilização de novas tecnologias para caracterizar madeiras tropicais é essencial para reduzir desperdícios na cadeia produtiva da indústria madeireira, aumentando o rendimento e produtividade do setor. Objetivou-se neste trabalho avaliar a utilização da tomografia de impulso na identificação do estado de sanidade e rendimento do lenho de árvores na floresta. O estudo foi conduzido em 01 hectare na Estação Experimental de Silvicultura Tropical – Núcleo ZF-2 - INPA. Foram selecionadas quatro árvores de Micrandopsis scleroxylon W. Rodr. para a utilização da tomografia de impulso; técnica essa que se baseia no cálculo da velocidade de propagação das ondas mecânicas no interior do lenho, originando uma imagem tomográfica. Utilizou-se a fórmula de Smalian para determinação dos volumes de madeira total e do oco, sendo sua diferença, o volume de madeira útil. Também foi estimado o volume de madeira útil a partir dos dados da tomografia de impulso. As árvores foram desdobradas na serraria para o cálculo do rendimento. Estes dados foram comparados com a classificação feita no software Envi 4.8, verificando a relação entre essas variáveis. A tomografia de impulso mostrou-se eficiente para estimar o estado de sanidade da árvore na floresta, demonstrando ser uma ferramenta útil no planejamento da exploração florestal.Palavra-chave: metodologia não destrutiva, manejo florestal, madeiras da Amazônia. IMPULSE TOMOGRAPHY IN THE EVALUATION SANITY AND PERFOMANCE OF \Micrandopsis scleroxylon W. Rodr. ABSTRACT:The use of new technologies to characterize tropical Wood is essential to reduce waste in wood industry productive chain, increasing the performance and productivity of the sector. The goal of this work was to access the use of the non-destructive method of impulse tomography in the identification of sanity state and wood performance of standing trees in the forest. The study was led in 01 hectare in Experimental Station of Tropical Silviculture – Campus ZF-2 - INPA. Four trees of the Micrandopsis scleroxylon W. Rodr. were selected for the impulse tomography application, technique based on the calculation of the wave propagation speed in the interior of the wood, giving rise to a tomographic image. It was used the Smalian formula to determine the total wood volume taking away the hollow volume equals the volume of useful wood. It was also estimated the useful volume using the data of the impulse tomography. The trees were unfolded in the sawmill for performance calculation. These data were compared to the classification done in the Envi 4.8 software, verifying the relation between the variables. The impulse tomography proved to be efficient to estimate the health status of the tree in the forest, showing to be a useful tool the forest exploration planning.Keywords: non-destructive methodology, forest management, Amazon wood. DOI: http://dx.doi.org/10.5935/2318-7670.v05nespa28

Non-destructive tests use techniques which allow a body to be evaluated without changing its physical, mechanical and dimensional features and without compromising its future use. Impulse tomography analysis is a non-destructive method which allows a piece of wood to be analyzed by passing mechanical waves through it, allowing researchers to evaluate its qualities in advance and detect the presence of defects. This research reports the assessment of the efficiency of impulse tomography as a technique for identifying defects and the in situ evaluation of tree wood from Amazonian timber species. The data were collected at INPA's Tropical Forestry Experimental Station (ZF-2), located at BR 174, Manaus/AM, in a plot 1 (one) hectare in size, where 7 species were chosen at random. For evaluation, the ARBOTOM pulse tomograph at DAP (diameter at breast height) was used to rapidly capture cross sectional images of the wood. Next, the trees were cut to evaluate cross sections of the wood by eye and samples were taken to determine the density of the wood. The results enabled researchers to detect the presence of distinct zones in the wood by varying the mechanical wave speed indicated by various colour zones revealed in the X-ray. These colour differences are attributable to variations in density related to the different wood substances in the tree. It was found that the wood density and mechanical wave velocity correlated with R² 0.647. The dynamic elastic modulus of the species studied was satisfactory, showing a good degree of resistance. Impulse tomography technique provides complete information and can assist forest managers to make a decision about tree felling that is guided by the assessment of the internal quality of the wood.

Illegal selective logging and forest fires occur on a large scale in the northern Brazilian Amazon, contributing to an increase in tree mortality and a reduction in forest carbon stock. A total of 120 plots of 0.25 ha (30 ha) were installed in transitional ecosystems or ecotones (LOt) between the forested shade-loving campinarana (Ld) and dense-canopy rainforest, submontane (Ds), in the National Forest (Flona) of Anau&aacute, southern Roraima. Measuring the diameters at breast height (DBH &ge, 10 cm) and the heights of 171 dead trees (fallen naturally, illegally exploited, and affected by forest fires), enabled the estimation of carbon content from the application of a biomass equation developed at Manaus, and the calculation of a correction factor, using the average height of the largest trees. From 2015&ndash, 2017, we mapped the real extent of illegal selective logging and forest fires across the region with CLASlite and INPE/Queimadas. From measurements of 14,730 live and dead trees across 30 hectares (491 &plusmn, 15 trees&middot, ha&minus, 1), the illegal selective logging and associated forest fires, and aggravation by severe El Ni&ntilde, o droughts resulted in an 8.2% mortality of trees (40 &plusmn, 9 dead trees&middot, 1) and a 3.5% reduction in forest carbon stock (6 &plusmn, 3 Mg&middot, 1) in the short-term. The surface area or influence of forest fires of very high density were estimated in the south-central region of Roraima (8374 km&sup2, ) and the eastern region of the Flona Anau&aacute, (37 km&sup2, ). Illegal selective logging and forest fires in forest areas totaled 357 km&sup2, in the mosaic area, and 6 km&sup2, within Flona Anaua. Illegal selective logging and forest fires in the years of severe El Ni&ntilde, o droughts threatened the maintenance of environmental services provided by Amazonian forests.

Volatile terpenoid resins represent a diverse group of plant defense chemicals involved in defense against herbivory, abiotic stress, and communication. However, their composition in tropical forests remains poorly characterized. As a part of tree identification, the ‘smell’ of damaged trunks is widely used, but is highly subjective. Here, we analyzed trunk volatile monoterpene emissions from 15 species of the genus Protium in the central Amazon. By normalizing the abundances of 28 monoterpenes, 9 monoterpene ‘fingerprint’ patterns emerged, characterized by a distinct dominant monoterpene. While 4 of the ‘fingerprint’ patterns were composed of multiple species, 5 were composed of a single species. Moreover, among individuals of the same species, 6 species had a single ‘fingerprint’ pattern, while 9 species had two or more ‘fingerprint’ patterns among individuals. A comparison of ‘fingerprints’ between 2015 and 2017 from 15 individuals generally showed excellent agreement, demonstrating a strong dependence on species identity, but not time of collection. The results are consistent with a previous study that found multiple divergent copies of monoterpene synthase enzymes in Protium. We conclude that the monoterpene ‘fingerprint’ database has important implications for constraining Protium species identification and phylogenetic relationships and enhancing understanding of physiological and ecological functions of resins and their potential commercial applications. © 2019 The Authors

Long-term studies of the dynamics of managed forests in tropical regions are lacking. This study aimed to evaluate the dynamics of a tropical forest, over a 25-year period, that was experimentally logged in 1987 and 1988 and submitted to three different cutting intensities. All trees with diameter at breast height (DBH) &ge, 10 cm have been measured annually since 1990. The three logging intensities that were applied were: light (T1)-trees harvested with DBH &ge, 55 cm, medium (T2)-DBH &ge, 50 cm, and heavy (T3)-DBH &ge, 40 cm. Control plots (T0) were also monitored. The highest mean annual mortality rates (1.82% &plusmn, 0.38), recruitment rates (2.93% &plusmn, 0.77) and diameter increments (0.30 &plusmn, 0.02 cm) occurred in the T3 treatment. Shifts in dynamics of the forest were mainly caused by a striking increase in a fast-growing pioneer species and their high mortality rates. The loss in stocking caused by mortality was greater than to that of replacement by recruitment. The results demonstrated that selective logging altered the natural dynamics of the forest through increased: mortality rates, recruitment and growth rates of the residual trees.

© 2018 Elsevier B.V. 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.

Uncertainties surrounding vegetation response to increased disturbance rates associated with climate change remains a major global change issue for Amazon forests. Additionally, turnover rates computed as the average of mortality and recruitment rates in the Western Amazon basin are doubled when compared to the Central Amazon, and notable gradients currently exist in specific wood density and aboveground biomass (AGB) between these two regions. This study investigates the extent to which the variation in disturbance regimes contributes to these regional gradients. To address these issues, we evaluated disturbance-recovery processes under two scenarios of increased disturbance rates in a complex Central Amazon forest using first ZELIG-TROP, a dynamic vegetation gap model which we calibrated using long-term inventory data, and second using the Community Land Model (CLM), a global land surface model that is part of the Community Earth System Model (CESM). Upon doubling the mortality rate in the Central Amazon to mirror the natural disturbance regime in the Western Amazon of ∼2% mortality, at steady-state, AGB significantly decreased by 41.9% and there was no significant difference between the modeled AGB of 104 Mg C ha−1 and empirical AGB from the western Amazon datasets of 107 Mg C ha−1. We confirm that increases in natural disturbance rates in the Central Amazon will result in terrestrial carbon loss associated with higher turnover. However, different processes were responsible for the reductions in AGB between the models and empirical datasets. We observed that with increased turnover, the subsequent decrease in wood density drives the reduction in AGB in empirical datasets. However, decrease in stand basal area was the driver of the drop in AGB in ZELIG-TROP, and decreased leaf area index (LAI) was the driver in CLM. Further comparisons found that stem density, specific wood density, and basal area growth rates differed between the two Amazonian regions. This suggests that: (1) the variability between regions cannot be entirely explained by the variability in disturbance regime, but rather potentially sensitive to intrinsic environmental factors; or (2) the models are not accurately simulating all forest characteristics in response to increased disturbances. Last, to help quantify the impacts of increased disturbances on climate and the earth system, we evaluated the fidelity of tree mortality and disturbance in a global land surface model: CLM. For a 100% increase in annual mortality rate, both ZELIG-TROP and CLM were in close agreement with each other and predicted a net carbon loss of 41.9 and 49.9%, respectively, with an insignificant effect on aboveground net primary productivity (ANPP). Likewise, a 20% increase in mortality every 50 years (i.e. periodic disturbance treatment) resulted in a reciprocal biomass loss of 18.3 and 18.7% in ZELIG-TROP and CLM, respectively.

© 2018 Elsevier B.V. Tree mortality is a critical process in forest ecosystems, as it influences floristic composition, structure, dynamics, carbon storage, and forest nutrient cycling. However, the mechanisms behind tree death in tropical regions are still poorly characterized. This lack of information is mainly because tree mortality data come from long-interval inventories and studies that measured tree death seasonally are scarce. Here we offer novel insights into the power of fine temporal scale observations and we use a natural history approach to understand the processes and mechanism of tree mortality. We monitored tree mortality every month during one year, in 10 ha of terra-firme forest. To determine the pathways of mortality, we considered the state of the tree at the start of the investigation and the pre and post-mortem characteristics. From November 2010 to October 2011, 67 out of 5808 trees died. Despite the 2010 drought, mortality was highly correlated with monthly rainfall (r = 0.85). In total, six pathways of mortality were assessed. Storms were the main cause of mortality, killing 45% of all dead trees, followed by Biotic/abiotic factors accounting for 30% of tree mortality. The high mortality registered in the rainy season was mostly (78%) due to healthy trees dying uprooted or snapped. Finally, we would benefit from studies that assess mortality on a monthly basis and in combination with quantitative long-term data, we can substantially improve our understanding of the mechanisms behind tree death in the tropics.

How plants respond physiologically to leaf warming and low water availability may determine how they will perform under future climate change. In 2015–2016, an unprecedented drought occurred across Amazonia with record-breaking high temperatures and low soil moisture, offering a unique opportunity to evaluate the performances of Amazonian trees to a severe climatic event. We quantified the responses of leaf water potential, sap velocity, whole-tree hydraulic conductance ( K wt ), turgor loss and xylem embolism, during and after the 2015–2016 El Niño for five canopy-tree species. Leaf/xylem safety margins (SMs), sap velocity and K wt showed a sharp drop during warm periods. SMs were negatively correlated with vapour pressure deficit, but had no significant relationship with soil water storage. Based on our calculations of canopy stomatal and xylem resistances, the decrease in sap velocity and K wt was due to a combination of xylem cavitation and stomatal closure. Our results suggest that warm droughts greatly amplify the degree of trees' physiological stress and can lead to mortality. Given the extreme nature of the 2015–2016 El Niño and that temperatures are predicted to increase, this work can serve as a case study of the possible impact climate warming can have on tropical trees. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

Author(s): Negron-Juarez, RI; Holm, JA; Marra, DM; Rifai, SW; Riley, WJ; Chambers, JQ; Koven, CD; Knox, RG; McGroddy, ME; Di Vittorio, AV; Urquiza-Munoz, J; Tello-Espinoza, R; Munoz, WA; Ribeiro, GHPM; Higuchi, N | Abstract: Tree mortality is a key driver of forest community composition and carbon dynamics. Strong winds associated with severe convective storms are dominant natural drivers of tree mortality in the Amazon. Why forests vary with respect to their vulnerability to wind events and how the predicted increase in storm events might affect forest ecosystems within the Amazon are not well understood. We found that windthrows are common in the Amazon region extending from northwest (Peru, Colombia, Venezuela, and west Brazil) to central Brazil, with the highest occurrence of windthrows in the northwest Amazon. More frequent winds, produced by more frequent severe convective systems, in combination with well-known processes that limit the anchoring of trees in the soil, help to explain the higher vulnerability of the northwest Amazon forests to winds. Projected increases in the frequency and intensity of convective storms in the Amazon have the potential to increase wind-related tree mortality. A forest demographic model calibrated for the northwestern and the central Amazon showed that northwestern forests are more resilient to increased wind-related tree mortality than forests in the central Amazon. Our study emphasizes the importance of including wind-related tree mortality in model simulations for reliable predictions of the future of tropical forests and their effects on the Earth' system.

Funding Information: Natural Environment Research Council (NERC), Grant/Award Number: NE/ N004655/1; NERC Consortium Grants “AMAZONICA”; BIO‐RED; European Research Council (ERC); The Gordon and Betty Moore Foundation; European Union's Seventh Framework Programme, Grant/ Award Number: 282664; Royal Society, Grant/Award Number: CH160091; Royal Society Wolfson Research Merit Award. Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate-induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long-term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO2 concentrations): maximum tree size, biogeographic water-deficit affiliation and wood density. Tree communities have become increasingly dominated by large-statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry-affiliated genera have become more abundant, while the mortality of wet-affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry-affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate-change drivers, but yet to significantly impact whole-community composition. The Amazon observational record suggests that the increase in atmospheric CO2 is driving a shift within tree communities to large-statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change. Publisher PDF

We examined the recovery and dynamics of living tree above-ground biomass (AGB) after selective logging in an Amazonian terra firme forest managed by a private company. The forest consisted of 24 blocks (including one set aside for conservation) selectively logged in different years on a managed schedule. Trees ≥10 cm in diameter at breast height (dbh) were surveyed in 2006 in 192 0.25-ha plots, in 2010 in 119 plots, and in 2012-2013 in 54 plots. A logistic growth model factoring in logging dynamics and mean AGB of a block in these years was established. Referencing the mean AGB of the unlogged forest, the model indicated that the logged forest would take on average 14 years to regain its preharvest AGB after selective logging at 1.9 trees ha-1 (dbh > 50 cm). In 2010 and 2012-2013, the AGB increased significantly for small and large trees (10-20 cm and >60 cm dbh, respectively) in the logged forest. In contrast, it decreased significantly for medium-sized trees (30-50 cm dbh) in the unlogged forest. Comparisons with the previous studies mainly conducted in the other regions of Amazon suggested that the estimated AGB recovery period with moderate logging intensity was almost appropriate and likely acceptable to forest managers.

The Amazon forest has been in evidence in global discussions about their role in control of global climate change, both by the ability to emit greenhouse gases into the atmosphere via burning or thinning, how to absorb carbon from the atmosphere by through the growth of the stand. This study analyzed data from a forest managed in 1987, in Manaus/AM. This work aimed to study the carbon stock and dynamics. The forest inventories were conducted in 15 hectares of permanent plots. The average rates of recruitment were 4.9%, 4.8%, 3.7% and 5% for control treatments and logging of 1/3, 1/2 and 2/3, respectively, and the average mortality rates were 3.1%, 6%, 4.8% and 6.7%, for control treatments and logging of 1/3, 1/2 and 2/3, respectively. The basal area (23.1 m2 ha-1 in 2005, 23.6 m2 ha-1 in 2007 and 23.7 m2 ha-1 in 2010), the volume (345 m3 ha-1 in 2005, 351.3 m3 ha-1 in 2007 and 353.7 m3 ha-1 in 2010) and the carbon content (149.2 t ha-1 in 2005, 151.8 t ha-1 in 2007 and 152.6 t ha-1 in 2010) increased in all measurements. However, the statistical difference between these values was not significant, so it was concluded that the forest was in equilibrium with the atmosphere during the period evaluated. A comparison of the carbon stock of the years measured with the stock pre-exploratory, in 1986, showed that in 2010 the carbon stock equaled the content before logging, meaning the forest recovery. © 2018 University of Sao Paolo. All rights reserved.

Author(s): Magnabosco Marra, Daniel; Trumbore, Susan E; Higuchi, Niro; Ribeiro, Gabriel HPM; Negron-Juarez, Robinson I; Holzwarth, Frederic; Rifai, Sami W; Dos Santos, Joaquim; Lima, Adriano JN; Kinupp, Valdely F; Chambers, Jeffrey Q; Wirth, Christian | Abstract: 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 ≥10ncm), 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 4-27nyears had biomass stocks as low as 65.2-91.7nMg/ha or 23%-38% of those in nearby undisturbed forests (~255.6nMg/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 (6.3n±n1.4nMgnha- 1 nyear- 1 ) those of undisturbed forests (~3.7nMgnha- 1 nyear- 1 ), biomass loss due to post-windthrow mortality was high (up to -7.5n±n8.7nMgnha- 1 nyear- 1 , 8.5nyears since disturbance) and unpredictable. Consequently, recovery to 90% of "pre-disturbance" biomass takes up to 40nyears. 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.

Aim: To examine variation in the phylogenetic diversity (PD) of tree communities across geographical and environmental gradients in Amazonia. Location: Two hundred and eighty-three c. 1 ha forest inventory plots from across Amazonia. Methods: We evaluated PD as the total phylogenetic branch length across species in each plot (PDss), the mean pairwise phylogenetic distance between species (MPD), the mean nearest taxon distance (MNTD) and their equivalents standardized for species richness (ses.PDss, ses.MPD, ses.MNTD). We compared PD of tree communities growing (1) on substrates of varying geological age; and (2) in environments with varying ecophysiological barriers to growth and survival. Results: PDss is strongly positively correlated with species richness (SR), whereas MNTD has a negative correlation. Communities on geologically young- and intermediate-aged substrates (western and central Amazonia respectively) have the highest SR, and therefore the highest PDss and the lowest MNTD. We find that the youngest and oldest substrates (the latter on the Brazilian and Guiana Shields) have the highest ses.PDss and ses.MNTD. MPD and ses.MPD are strongly correlated with how evenly taxa are distributed among the three principal angiosperm clades and are both highest in western Amazonia. Meanwhile, seasonally dry tropical forest (SDTF) and forests on white sands have low PD, as evaluated by any metric. Main conclusions: High ses.PDss and ses.MNTD reflect greater lineage diversity in communities. We suggest that high ses.PDss and ses.MNTD in western Amazonia results from its favourable, easy-to-colonize environment, whereas high values in the Brazilian and Guianan Shields may be due to accumulation of lineages over a longer period of time. White-sand forests and SDTF are dominated by close relatives from fewer lineages, perhaps reflecting ecophysiological barriers that are difficult to surmount evolutionarily. Because MPD and ses.MPD do not reflect lineage diversity per se, we suggest that PDss, ses.PDss and ses.MNTD may be the most useful diversity metrics for setting large-scale conservation priorities. © 2015 John Wiley & Sons Ltd.

Made available in DSpace on 2018-12-11T16:48:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-09-01 National Research Council of Science and Technology Amazon forests are fire-sensitive ecosystems and consequently fires affect forest structure and composition. For instance, the legacy of past fire regimes may persist through some species and traits that are found due to past fires. In this study, we tested for relationships between functional traits that are classically presented as the main components of plant ecological strategies and environmental filters related to climate and historical fires among permanent mature forest plots across the range of local and regional environmental gradients that occur in Amazonia. We used percentage surface soil pyrogenic carbon (PyC), a recalcitrant form of carbon that can persist for millennia in soils, as a novel indicator of historical fire in old-growth forests. Five out of the nine functional traits evaluated across all 378 species were correlated with some environmental variables. Although there is more PyC in Amazonian soils than previously reported, the percentage soil PyC indicated no detectable legacy effect of past fires on contemporary functional composition. More species with dry diaspores were found in drier and hotter environments. We also found higher wood density in trees from higher temperature sites. If Amazon forest past burnings were local and without distinguishable attributes of a widespread fire regime, then impacts on biodiversity would have been small and heterogeneous. Alternatively, sufficient time may have passed since the last fire to allow for species replacement. Regardless, as we failed to detect any impact of past fire on present forest functional composition, if our plots are representative then it suggests that mature Amazon forests lack a compositional legacy of past fire. Laboratório de Ecologia Vegetal Universidade do Estado de Mato Grosso (UNEMAT) Instituto de Ciência e Tecnologia Universidade Estadual Paulista (Unesp) College of Science and Engineering and Centre for Tropical Environmental and Sustainability Science (TESS) James Cook University School of Geography University of Leeds Biological Dynamics of Forest Fragments Project National Institute for Amazonian Research (INPA) and Smithsonian Tropical Research Institute Laboratoire EDB Université Paul Sabatier Instituto de Investigaciones de la Amazonía Peruana Coordenação de Botânica Museu Paraense Emilio Goeldi National Institute for Amazonian Research (INPA) Department of Environmental Science and Policy George Mason University Environmental Change Institute School of Geography and the Environment University of Oxford Proyecto Flora del Peru Jardin Botanico de Missouri Puyo Universidad Estatal Amazónica Instituto de Ciencias Naturales Universidad Nacional de Colombia Universidad de Los Andes Naturalis Biodiversity Center Systems Ecology Free University, De Boelelaan 1087 University of Washington Geography College of Life and Environmental Sciences University of Exeter Instituto de Ciência e Tecnologia Universidade Estadual Paulista (Unesp) National Research Council of Science and Technology: PELD 403725/2012-7 National Research Council of Science and Technology: PPBio 457602/2012-0 National Research Council of Science and Technology: PVE 401279/2014-6

Windthrows are a recurrent disturbance in Amazonia and are an important driver of forest dynamics and carbon storage. In this study, we present for the first time the seasonal and interannual variability of windthrows, focusing on Central Amazonia, and discuss the potential meteorological factors associated with this variability. Landsat images over the 1998-2010 time period were used to detect the occurrence of windthrows, which were identified based on their spectral characteristics and shape. Here, we found that windthrows occurred every year but were more frequent between September and February. Organized convective activity associated with multicell storms embedded in mesoscale convective systems, such as northerly squall lines (that move from northeast to southwest) and southerly squall lines (that move from southwest to northeast) can cause windthrows. We also found that southerly squall lines occurred more frequently than their previously reported ~50 year interval. At the interannual scale, we did not find an association between El Niño-Southern Oscillation (ENSO) and windthrows. © 2017 by the author.

The Eschweilera genus has great ecological and economic importance due to its wide abundance in the Amazon basin. One potential use for the Eschweilera genus is in forest management, where just a few trees are removed per hectare. In order to improve the forest management in the Amazon, this study assessed two critical issues: volume equations fitted for a single genus and the development of a non-destructive method using climbing techniques. The equipment used to measure the sample trees included: climbing rope, ascenders, descenders, and carabiners. To carry out the objectives of this study, 64 trees with diameter at breast height (DBH) = 10 cm were selected and measured in ZF-2 Tropical Forestry Station near the city of Manaus, Brazil. Four single input models with DBH and four dual input models with DBH and merchantable height (H) were tested. The Husch model (V = a × DBHb) presented the best performance (R2 = 0.97). This model does not require the merchantable height, which is an important advantage, because of the difficulty in measuring this variable in tropical forests. When the merchantable height data are collected using accurate methods, the Schumacher and Hall model (V = a × DBHb × Hc) is the most appropriated. Tree climbing techniques with the use of ropes, as a non-destructive method, is a good alternative to measure the merchantable height, the diameter along the stem, and also estimate the tree volume (m3) of the Eschweilera genus in the Amazon basin. © 2017 by the authors.

The aim of this study was to develop and apply an implicit yield model based on the Weibull probability density function for the predictions of yield by diameter class for a logged tropical rainforest located in the center of Amazon. The study area is located in the Tropical Forest Experimental Station, 90 km from the urban center of Manaus, AM, Brazil. The data came from 12 permanent 1 ha plots, logged at three levels of basal area removal intensities. In each plot all individuals with DBH ⩾ 10 cm between 1990 and 2009 were measured annually. Functions were used to describe the dynamics of tree abundance (recruitment and mortality), basal area, summed diameters per hectare, and a new statistic for classification of forest yield, in order to estimate the sample moments of minimum, average and quadratic mean diameter in 2009. The Weibull diameter distribution was fitted using the method of moments and validated by data collected in 2009. The inclusion of variables that reflect the productive potential in the proposed model facilitates the evaluation of forests that have undergone changes in its structural characteristics in the different sites. The use of an alternative technique for classification led to a better understanding of the management regimes applied to the forests under analysis. The proposed model proved efficient by the Kolmogorov–Smirnov test, and thus may be used in updating inventory statistics, calculations of annual cut and in planning forest by companies that work in uneven aged and mixed forests in different sites of the Amazon.

We studied plant water use characteristics of the tree Theobroma grandiflorum (Cupuacu, (Willd. ex Spreng.) Schum., Malvaceae) and the palm Euterpe precatoria (Acai, Mart., Arecaceae) both native to the Amazon and commonly occurring in the region. The tree species is occurring mainly in the terra firme forest whereas the palm species is restricted to the extreme habitats in stream valleys. This study was conducted in a small fruit plantation close to the city of Manaus, in the Central Amazon, Brazil. The main objective of this study was to compare water use characteristics in relation to plant structural traits. Three representative individuals of each species were equipped with Granier-type thermal dissipation probes to measure sap flux density. Water use scaled independent of species with the size of the conductive xylem area (r2=0.85). Furthermore, we found a clear species-specific scaling of water use with plant-size. Overall, palms had a 3.5-fold higher water consumption compared to trees with similar stem diameter and/or plant height. Palms transpired a mean of 1.67 mm m-2 of water per unit crown projection area per day, whereas trees transpired only 0.30 mm m-2 per day, resulting in a 5.6 times lower transpiration rate. We assume that especially the unbalanced plant height/water use ratio of the palms might be limiting the height growth due to increasing hydraulic limitations. Hence, palms are restricted to extreme habitats with higher water availability and usually do not co-occur with more efficient and taller broad leaved tree species in the terra firme forest.

This study sought to classify the productivity of a representative area of tropical forest, as well as to analyze the relationship between the structural variability of pioneer species and the yield of three management regimes. The study area is located at the Tropical Forestry Experimental Station belonging to INPA (National Institute for Amazon Research), approximately 90 km from downtown Manaus, in the State of Amazonas, Brazil. Data were collected from twelve 1 ha sample plots. Diameter was measured annually for all individuals with DBH 10 cm between the years 1990 and 2008. Pioneer species served as the basis for calculating the Diameter Variability Index VI% over time. Three classes of variability were established according to the guide curve technique used for site classification by the dominant height. Biological and probabilistic functions were used to model VI% as a function of time of exploitation, as well as the volumetric yield over time as a function of VI%. There is an inverse relationship between VI% and yield, which allows classification of site yield and conception of global yield models to which present good statistics of precision and adjustment, allowing the prediction of productivity and their dynamics throughout the time.

Tropical forests, specially the Amazon, are important ecosystems in research on the effects of climate change on biological systems and their functioning. The main relationship between the forest and the climate is the carbon fluxes and stock. Although carbon stock estimates of tropical forests are an issue and still raise many uncertainties. This study aims to present the main literature references and the huge effort to sample the forests of Central Amazon. Many attempts to estimate the carbon stock of the Amazon rainforest resulted in high uncertainties due to sampling and allometric constrains. After developing an allometric equation, based on destructive method and adapted to each different site based on dominant height, sampling over 1800 plots in primary and selectively logged non-flooded forests, across the State of Amazonas, the estimated average of total (tree’s above- and below-ground) carbon stock is 159.8 ± 9.2 Mg C ha−1.

RAINFOR is a long-term collaboration to understand the dynamics of Amazon ecosystems from the ground-up. Using a framework for systematic monitoring of the forests centred on replicated, permanent plots that measure ecosystem composition and behaviour over time, researchers carefully track the lives, deaths, and identities of trees at hundreds of plots basin-wide. Here we summarise findings from the last three decades in terms of the structural, dynamic, and compositional changes which have affected mature Amazon forests. At large scale, Amazon forests have experienced accelerated growth and mortality for decades, with a long-term increase in biomass carbon stocks within remaining intact forests. The results suggest that the tropical biome has been responding for many years to large-scale drivers of atmospheric and climatic change. Repeated, standardised, careful, and adequately replicated on-the-ground measurements, coupled with targeted experiments and physiological measurements, are key to making significant progress towards understanding changes in forest biodiversity and carbon.

Precise estimation of biomass at a regional scale is required for evaluating forest carbon stocks throughout the Amazon. We examined six types of allometric models to identify the best estimator of biomass in primary forests (terra firme) in the northwestern sector of the Brazilian Amazon. We also tested six regression models for estimating tree height. We developed each allometric model using measurements of 101 trees excavated in a primary forest distributed along the upper Rio Negro. A simple power function with stem diameter at breast height D as a single variable was selected as the best model for estimating each biomass component, i.e. above-ground total mass AGW, below-ground total mass BGW, and whole individual mass. Among models developed to estimate tree height H from D, we selected a regression model with a coefficient corresponding to an asymptotic height as the best fit. The D–AGW relationship at our study site differed significantly from models developed previously for other regions of the Amazon. We explain this regional variation in part by regional differences in D–H relationships of sample trees. The D–BGW relationship at our site also differed significantly from that in the central Amazon. However, AGW–BGW relationships were consistent between the upper Rio Negro forest and other forests in the central Amazon, in that the BGW–AGW ratio was constant as 0.136 regardless of tree size. On the basis of D-based allometry and census data from 23 plots established in the upper Rio Negro region, we estimated a stand-level total biomass (dry mass) of 252.6 Mg ha−1. This estimate is at least 73% lower than the potential stand biomass for the region previously suggested by several meta-analyses.

Treefall gaps play important roles in both forest dynamics and species diversity, but variability across the full range of gap sizes has not been reported at a regional scale due to the lack of a consistent methodology for their detection. Here we demonstrate the sensitivity of Landsat data for detecting gaps at the subpixel level in the Manaus region, Central Amazon. Spectral mixture analysis (SMA) on treefall gaps was used to map their occurrence across a 3.4 × 104 km2 landscape using the annual change in non-photosynthetic vegetation (ΔNPV) as the change metric. Thirty randomly selected pixels with a spectral signature of a treefall event (i.e. high ΔNPV) were surveyed in the field. The most frequent single-pixel gap size detected using Landsat was ~ 360 m2, and the severity of the disturbance (ΔNPV) exhibited a significant (r2 = 0.32, p = 0.001) correlation with the number of dead trees (> 10 cm diameter at breast height), enabling quantification of the number of downed trees in each gap. To place the importance of these single-pixel disturbances into a broader context, the cumulative disturbance of these gaps was equivalent to 40% of the calculated deforestation across the Manaus region in 2008. Most detected single-pixel gaps consisted of six to eight downed trees covering an estimated area of 250–900 m2. These results highlight the quantitative importance of small blowdowns that have been overlooked in previous satellite remote sensing studies.

Esta pesquisa teve por objetivo estudar o incremento em diâmetro, área basal e volume, o ingresso e a mortalidade de uma floresta ombrófila aberta/estacional no município de Marcelândia. Os dados são provenientes de 69 parcelas permanentes instaladas e medidas em 2001 e remedidas em 2003 e 2007. Foram avaliados o número de indivíduos e os incrementos em diâmetro, área basal e volume para o período de 2001 a 2007. O ingresso foi determinado como sendo as árvores que atingiram ou ultrapassaram o diâmetro de 17 cm. A mortalidade foi calculada pela soma de todas as árvores com diâmetro igual ou superior a 17 cm encontradas mortas em cada medição. No período considerado de seis anos, teve como resultado para o incremento em diâmetro, área basal e volume respectivamente, 0,34 cm; 0,22 m².ha-1 e 2,11 m³.ha-1. Os valores médios para as taxas de mortalidade e ingresso foram, respectivamente, 0,78% e 0,30%. This research aimed to study the increase in diameter, basal area, volume, the entry, and the mortality of an open/seasonal ombrophilous forest in the city of Marcelândia. Data were collected in 69 permanent plots established in 2001 and remeasured in 2003 and 2007. The number of individuals and the increases in diameter, basal area, and volume for the period 2001 to 2007 were evaluated. The entry was determined by the trees that have reached or exceeded a diameter of 17 cm. Mortality was calculated as the sum of all found dead trees in each measurement with a diameter equal or more than 17 cm. In the considered period of six years, the results to the increase in diameter, basal area, and volume were respectively, 0.34 cm, 0.22 m².ha-1, and 2.11 m³.ha-1. The average values for the mortality rates and entry respectively were 0.78% and 0.30%.

Aim To assess the hypotheses that compound leaves of trees in the Amazon forest are an adaptation to drought and/or rapid growth. Location Amazon rain forest, South America. Methods Genera from 137 permanent forest plots spread across Amazonia were classified into those with compound leaves and those with simple leaves. Metrics of compound leaf prevalence were then calculated for each plot and regression models that accounted for spatial autocorrelation were used to identify associations between climate variables and compound leaf structure. We also tested for associations between compound leaf structure and a variety of ecological variables related to life history and growth strategies, including wood density, annual increase in diameter and maximum height. Results One plant family, Fabaceae, accounts for 53% of compound-leaved individuals in the dataset, and has a geographical distribution strongly centred on north-east Amazonia. On exclusion of Fabaceae from the analysis we found no significant support for the seasonal drought hypothesis. However, we found evidence supporting the rapid growth hypothesis, with possession of compound leaves being associated with faster diameter growth rates and lower wood densities. Main conclusion This study provides evidence that possession of compound leaves constitutes one of a suite of traits and life-history strategies that promote rapid growth in rain forest trees. Our findings highlight the importance of carefully considering the geographical distribution of dominant taxa and spatial clustering of data points when inferring ecological causation from environment–trait associations.

Leaves in tropical forests come in an enormous variety of sizes and shapes, each of which can be ultimately viewed as an adaptation to the complex problem of optimising the capture of light for photosynthesis. However, the fact that many different shape "strategies" coexist within a habitat demonstrate that there are many other intrinsic and extrinsic factors involved, such as the differential investment in support tissues required for different leaf lamina shapes. Here, we take a macrogeographic approach to understanding the function of different lamina shape categories. Specifically, we use 106 permanent plots spread across the Amazon rainforest basin to: 1) describe the geographic distribution of some simple metrics of lamina shape in plots from across Amazonia, and; 2) identify and quantify relationships between key environmental parameters and lamina shape in tropical forests. Because the plots are not randomly distributed across the study area, achieving this latter objective requires the use of statistics that can account for spatial auto-correlation. We found that between 60–70% of the 2791 species and 83 908 individual trees in the dataset could be classified as having elliptic leaves (= the widest part of the leaf is on an axis in the middle fifth of the long axis of the leaf). Furthermore, the average Amazonian tree leaf is 2.5 times longer than it is wide and has an entire margin. Contrary to theoretical expectations we found little support for the hypothesis that narrow leaves are an adaptation to dry conditions. However, we did find strong regional patterns in leaf lamina length-width ratios and several significant correlations with precipitation variables suggesting that water availability may be exerting an as yet unrecognised selective pressure on leaf shape of rainforest trees. Some support was found for the hypothesis that narrow leaves are an adaptation to low nutrient soils. Furthermore, we found a strong correlation between the proportion of trees with non-entire laminas (dissected, toothed, etc.) and mean annual temperature once again supporting the well documented association that provides a basis for reconstructing past temperature regimes.

Addressing spatial variability in nitrogen (N) availability in the Central Brazilian Amazon, we hypothesized that N availability varies among white-sand vegetation types (campina and campinarana) and lowland tropical forests (dense terra-firme forests) in the Central Brazilian Amazon, under the same climate conditions. Accordingly, we measured soil and foliar N concentration and N isotope ratios (δ15N) throughout the campina-campinarana transect and compared to published dense terra-firme forest results. There were no differences between white-sand vegetation types in regard to soil N concentration, C:N ratio and δ15N across the transect. Both white-sand vegetation types showed very low foliar N concentrations and elevated foliar C:N ratios, and no significant difference between site types was observed. Foliar δ15N was depleted, varying from −9.6 to 1.6‰ in the white-sand vegetations. The legume Aldina heterophylla had the highest average δ15N values (−1.5‰) as well as the highest foliar N concentration (2.1%) while the non-legume species had more depleted δ15N values and the average foliar N concentrations varied from 0.9 to 1.5% among them. Despite the high variation in foliar δ15N among plants, a significant and gradual 15N-enrichment in foliar isotopic signatures throughout the campina–campinarana transect was observed. Individual plants growing in the campinarana were significantly enriched in 15N compared to those in campina. In the white-sand N-limited ecosystems, the differentiation of N use seems to be a major cause of variations observed in foliar δ15N values throughout the campina–campinarana transect.

Nitrogen variations at different spatial scales and integrated across functional groups were addressed for lowland tropical forests in the Brazilian Amazon as follows: (1) how does N availability vary across the region over different spatial scales (regional × landscape scale); (2) how are these variations in N availability integrated across plant functional groups (legume × non-legume trees). Leaf N, P, and Ca concentrations as well the leaf N isotope ratios (δ15N) from a large set of legume and non-legume tree species were measured. Legumes had higher foliar N/Ca ratios than non-legumes, consistent with the high energetic costs in plant growth associated with higher foliar P/Ca ratios found in legumes than in non-legumes. At the regional level, foliar δ15N decreased with increasing rainfall. At the landscape level, N availability was higher in the forests on clayey soils on the plateau than in forests on sandier soils. The isotope as well as the non-isotope data relationships here documented, explain to a large extent the variation in δ15N signatures across gradients of rainfall and soil. Although at the regional level, the precipitation regime is a major determinant of differences in N availability, at the landscape level, under the same precipitation regime, soil type seems to be a major factor influencing the availability of N in the Brazilian Amazon forest.

© 2015 by the authors; licensee MDPI, Basel, Switzerland. Prolonged drought stress combined with high leaf temperatures can induce programmed leaf senescence involving lipid peroxidation, and the loss of net carbon assimilation during early stages of tree mortality. Periodic droughts are known to induce widespread tree mortality in the Amazon rainforest, but little is known about the role of lipid peroxidation during drought-induced leaf senescence. In this study, we present observations of green leaf volatile (GLV) emissions during membrane peroxidation processes associated with the combined effects of high leaf temperatures and drought-induced leaf senescence from individual detached leaves and a rainforest ecosystem in the central Amazon. Temperature-dependent leaf emissions of volatile terpenoids were observed during the morning, and together with transpiration and net photosynthesis, showed a post-midday depression. This post-midday depression was associated with a stimulation of C5 and C6 GLV emissions, which continued to increase throughout the late afternoon in a temperature-independent fashion. During the 2010 drought in the Amazon Basin, which resulted in widespread tree mortality, green leaf volatile emissions (C6 GLVs) were observed to build up within the forest canopy atmosphere, likely associated with high leaf temperatures and enhanced drought-induced leaf senescence processes. The results suggest that observations of GLVs in the tropical boundary layer could be used as a chemical sensor of reduced ecosystem productivity associated with drought stress.

Despite orders of magnitude difference in atmospheric reactivity and great diversity in biological functioning, little is known about monoterpene speciation in tropical forests. Here we report vertically resolved ambient air mixing ratios for 12 monoterpenes in a central Amazon rainforest including observations of the highly reactive cis-β-ocimene (160 ppt), trans-β-ocimene (79 ppt), and terpinolene (32 ppt) which accounted for an estimated 21% of total monoterpene composition yet 55% of the upper canopy monoterpene ozonolysis rate. All 12 monoterpenes showed a mixing ratio peak in the upper canopy, with three demonstrating subcanopy peaks in 7 of 11 profiles. Leaf level emissions of highly reactive monoterpenes accounted for up to 1.9% of photosynthesis confirming light-dependent emissions across several Amazon tree genera. These results suggest that highly reactive monoterpenes play important antioxidant roles during photosynthesis in plants and serve as near-canopy sources of secondary organic aerosol precursors through atmospheric photooxidation via ozonolysis. © 2015. The Authors.

Native fruiting plants are widely cultivated in the Amazon, but little information on their water use characteristics can be found in the literature. To explore the potential impacts of plantations on local to regional water balance, we studied plant water use characteristics of two native fruit plants commonly occurring in the Amazon region. The study was conducted in a mixed fruit plantation containing a dicot tree species (Cupuaçu, Theobroma grandiflorum) and a monocot palm species (Açai, Euterpe oleracea) close to the city of Manaus, in the Central Amazon. Scaling from sap flux measurements, palms had a 3.5-fold higher water consumption compared to trees with a similar diameter. Despite the high transpiration rates of the palms, our plantation had only one third of the potential water recycling capacity of natural forests in the area. Converting natural forest into such plantations will thus result in significantly higher runoff rates. © 2015 by the authors.

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades1, 2, with a substantial fraction of this sink probably located in the tropics3, particularly in the Amazon4. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity5. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale1, 2, and is contrary to expectations based on models.

Quantifying age structure and tree growth rate of Amazonian forests is essential for understanding their role in the carbon cycle. Here, we use radiocarbon dating and direct measurement of diameter increment to document unexpectedly slow growth rates for trees from three locations spanning the Brazilian Amazon basin. Central Amazon trees, averaging only ≈1 mm/year diameter increment, grow half as fast as those from areas with more seasonal rainfall to the east and west. Slow growth rates mean that trees can attain great ages; across our sites we estimate 17-50% of trees with diameter >10 cm have ages exceeding 300 years. Whereas a few emergent trees that make up a large portion of the biomass grow faster, small trees that are more abundant grow slowly and attain ages of hundreds of years. The mean age of carbon in living trees (60-110 years) is within the range of or slightly longer than the mean residence time calculated from C inventory divided by annual C allocation to wood growth (40-100 years). Faster C turnover is observed in stands with overall higher rates of diameter increment and a larger fraction of the biomass in large, fast-growing trees. As a consequence, forests can recover biomass relatively quickly after disturbance, whereas recovering species composition may take many centuries. Carbon cycle models that apply a single turnover time for carbon in forest biomass do not account for variations in life strategy and therefore may overestimate the carbon sequestration potential of Amazon forests. © 2005 by The National Academy of Sciences of the USA.

Information on diameter increment and growth patterns for individual trees are important tools for forest management primarily to: (i) select tree species for logging; (ii) selecting tree species for protection; (iii) estimate cutting cycles and (iv) to prescribe silvicultural treatments. Most growth and yield studies in tropical moist forests have emphasized only the stand level instead of individual trees. This study dealt with the analysis of individual growth patterns for 272 trees distributed over two transects (East–West and North–South) measuring 20 m ×2500 m, which were stratified by plateau, slope and “baixio” (lowland areas near small streams), and tree diameter at breast height (DBH) classes ( 10 cm ≤ DBH cm, 30 cm ≤ DBH cm and DBH≥50 cm). For each tree, a metal “dendrometer” band was fixed to the trunk and growth in circumference was measured with digital calipers. Measurements were carried out for 19 months, from June 1999 to December 2000; for this study, only 12 months of year 2000 were considered. Individual growth pattern varied significantly over time (P=0.00), and slightly (P=0.08) when the interaction months and DBH classes was included; on the other hand, the signal was very weak (P=0.25) when topographical classes were added to the later interaction, and no signal at all (P=0.89) when the interaction between months, diameter and topographical classes were analyzed. Mean annual diameter increment considering all 272 monitored trees was 1.64±0.21 mm per year (95% CI), falling within the range estimated for the Brazilian Amazon region (1.4–2 mm per year).

The Amazon basin is likely to be increasingly affected by environmental changes: higher temperatures, changes in precipitation, CO2 fertilization and habitat fragmentation. To examine the important ecological and biogeochemical consequences of these changes, we are developing an international network, RAINFOR, which aims to monitor forest biomass and dynamics across Amazonia in a co-ordinated fashion in order to understand their relationship to soil and climate. The network will focus on sample plots established by independent researchers, some providing data extending back several decades. We will also conduct rapid transect studies of poorly monitored regions. Field expeditions analysed local soil and plant properties in the first phase (2001–2002). Initial results suggest that the network has the potential to reveal much information on the continental-scale relations between forest and environment. The network will also serve as a forum for discussion between researchers, with the aim of stand...