Ecohidrologia de Espécies Arbóreas de Terra Firme na Amazônia

The Amazon is the largest tropical forest in the world with great importance in the global biogeochemical cycles. Under climate change scenarios, a mechanistic understanding of the water cycle from individual trees to landscapes is needed to predict changes in the forest structure and function. In the Amazon basin, an estimated 25-50% of precipitation is recycled back to the atmosphere through forest transpiration. At the leaf level, transpiration flux is a function of vapor pressure deficit (VPD) and stomatal conductance (gs), according to Fick’s laws of diffusion. Also, leaf temperature (Tleaf), net radiation, and soil moisture are often considered important. In this study, we present in situ field observations of environmental (direct solar radiation, air temperature, and VPD) and physiological (sap velocity, stomatal conductance, and leaf water potential) variables and their correlations with Tleaf during the 2015-2016 ENSO and the regular seasons 2017 and 2018. In order to observe the interactions between physiological variables and fast-changing environmental conditions, we collected a high temporal frequency data (15-60 min) in two primary rainforest sites one located in the Central Amazon within the limits of the Experimental Station of Tropical Forestry (ZF-2) near the K-34 tower site, and another in the Eastern Amazon within the limits of the Tapajós National Forest at the the K-67 tower site. Our study shows that the interactions between the observed environmental and physiological variables can be explained by the hysteresis phenomena. The temporal difference between the peak of stomatal conductance (late morning to midday) and the peak of VPD (early afternoon) is one of the major regulators of the sap velocity hysteresis patterns. Also, for the first time, the hysteresis patterns between Tleaf and Tair were described. During the 2015-2016 ENSO, the differences between Tleaf and air temperature (Tair) reached almost 8°C, and generally, Tleaf was higher than Tair during the morning period to early afternoon, and lower than Tair during the late afternoon and night. With the leaf temperature data, it was possible to calculate the true VPD (ΔVPD), which is the pressure gradient between the substomatal cavity and the boundary layer of the air near the leaf surface. The complexity of the observed physiological and environmental variables that can affect the transpiration dynamics reinforces the importance of detailed analyzes during periods of climatic anomalies such as El Niño. The presented data can provide new perspectives for the improvement of current Earth System Models (ESMs).A floresta amazônica é a maior floresta tropical do mundo e possui grande importância nos fluxos globais de água e carbono, ocupando papel importante nos cenários futuros de mudança climática. Para se ter uma maior compreensão dos ciclos da água e do carbono, um melhor entendimento acerca das interações entre a fisiologia das plantas e fatores ambientais se faz necessário. Estima-se que cerca de 25-50 % da precipitação na bacia Amazônica é reciclada de volta para a atmosfera por meio da transpiração da floresta. Os mecanismos envolvidos na transpiração de espécies vegetais, embora sejam bem descritos na literatura, carecem de informações nas regiões tropicais, especialmente na Amazônia. O objetivo principal desta tese de doutoramento foi analisar a dinâmica da transpiração de árvores de terra firme da Amazônia e os fatores que a controlam. Para isto, o estudo foi conduzido em duas áreas distintas: uma na Amazônia Central dentro dos limites da Estação Experimental de Silvicultura Tropical (ZF-2) no sítio da torre K-34, e outra na Amazônia Oriental, dentro dos limites da Floresta Nacional do Tapajós, no sítio da torre K-67. Nos dois sítios as árvores-amostra foram sensorizadas numa alta intensidade temporal de coleta de dados (intervalos de 5 a 30 minutos) e também submetidas a experimentos de 12 horas de duração (curvas diárias). As variáveis obtidas foram: velocidade de seiva xilemática (cm hr-1), intensidade de luz direta (W m-2), temperatura foliar (°C), temperatura do ar (°C), déficit de pressão de vapor (VPD), potencial hídrico foliar (ΨL), condutância estomática (gs), além de parâmetros dendrométricos tais como o diâmetro à altura do peito (DAP), altura total (Ht) e a posição da árvore no dossel. Os dados foram coletados nos anos de 2015, 2016, 2017 e 2018, somando um total de quatro anos e 21 árvores estudadas. O biênio 2015-2016 esteve sob influência de um forte El Niño. Muitas análises utilizaram este período como comparativo, uma vez que as árvores foram expostas à níveis drásticos de seca e altas temperaturas. Verificou-se que a dinâmica da transpiração é governada pelo fenômeno de histerese. Esta histerese pode ser descrita como o resultado do deslocamento temporal da radiação solar direta, que tende a apresentar seus máximos perto do final da manhã, e o VPD que tende a apresentar seus valores máximos no começo da tarde. Além da transpiração, o fenômeno de histerese também rege a dinâmica de duas importantes variáveis: a temperatura do ar e a temperatura foliar. Com os dados de temperatura foliar é possível calcular o verdadeiro VPD (ΔVPD), sendo o gradiente de pressão entre a folha e a atmosfera. Além disto, verificou-se que durante o El Niño 2015-2016 a temperatura foliar diferiu da temperatura do ar numa ordem de até 8℃. A complexidade das variáveis fisiológicas e ambientais que podem afetar a dinâmica da transpiração, como demonstrado, reforça a importância de análises detalhadas durante períodos de anomalias climáticas como o El Niño. Estes dados fornecem novas perspectivas para o aprimoramento dos modelos climáticos atuais

Equações volumétricas e o modelo que utiliza o fator de forma médio: um estudo de caso na Amazônia Central

Models were tested to fit observed data from merchantable tree species of two distinct locations of Central Amazonia. To choice the best models, we sought to compare these models with one of the widest used model to estimate the volume of wood in the Amazon rainforest. This model consists of using the cylinder volume adapted (π x DBH²/4 x Hc) multiplied by a mean form factor (0.7). To carry out this study, 54 sample trees with DBH ≥ 30 cm were taken from an area clear cut for agriculture projects in Rorainópolis, Southern Roraima. Furthermore, 64 sample trees of the genus Eschweilera with DBH≥10 cm were scaled with climbing technical in E.E.S.T/INPA (ZF-2). In both areas eight volume models were tested: four models of single entry with independent variable diameter at breast height (DBH) and four models of double-entry with independent variables DBH and commercial height (Hc). In Rorainópolis, eight models were additionally tested with the substitution of the independent variable DAP by the independent variable diameter of the stump (Dtoco). The model that best fit the data and the reality of the south region of Roraima was the Husch (V = 0.000503 * DBH^2.157162) due to their consistent stats (R² adjusted 0.8997 and Syx 1.38 m³) and for not having the commercial height as an independent variable. To calculate the volume of wood from the independent variable Dtoco, the best model is the simple entry Husch (V = 0.002603 * DBH^1.761132) (R²adj. 0.7890 and Syx 1.93 m³). However, for the areas that have stumps and the trees felled we can measure the commercial height and use the Schumacher e Hall model of double entry (V = 0.000263 * Dtoco^1.782244 * Hc^0.765729) can also be used since it had the best statistics among all models with these variables (R ² adj. 0.8723 and Syx 1.51 m³). In ZF-2, the model of Husch (V = 0.000320 * DBH^2.242681) is the most suitable for calculating wood volume for the genus Eschweilera, because this model presents very consistent statistics (R²adj. 0.9750 and Syx 0.07 m³) and it does not have the commercial height as an independent variable. The model that uses the mean form factor is not the best method to estimate the volume of wood in both study areas. This calculation method is still prevalent in Rorainópolis and is closely related to the illegal deforestation in the region, since in forest inventories Hc is overrated which results in higher no sampling errors.Foram ajustados diversos modelos de volume comercial com casca em dois locais distintos da Amazônia Central. Os melhores modelos foram comparados com o modelo mais difundido para estimativa do volume de madeira da floresta Amazônica. Este modelo consiste em utilizar o volume do cilindro modificado (π x DAP²/4 x Hc) multiplicado por um fator de forma médio igual a 0,7. Para isto, foram cubadas 54 árvores-amostra com DAP ≥ 30 cm em uma área de desmatamento autorizado localizado no município de Rorainópolis, sul do estado de Roraima. Também foram cubadas em pé com técnicas de escalada, 64 árvores-amostra do gênero Eschweilera com DAP ≥ 10 cm na E.E.S.T/INPA (ZF-2) localizada a 90 km de Manaus. Em ambas as áreas foram testados oito modelos volumétricos, sendo quatro modelos de simples entrada com a variável independente DAP e quatro modelos de dupla entrada com as variáveis independentes DAP e altura comercial (Hc). Em Rorainópolis foram testados adicionalmente oito modelos com a substituição da variável independente DAP pela variável independente diâmetro do toco (Dtoco). O modelo que melhor se ajustou aos dados e à realidade da região sul de Roraima foi o de Husch (V = 0,000503 * DAP^2,157162) devido aos seus indicadores robustos (R²ajust = 0,899 e Syx = 1,38 m³) e por não possuir a altura comercial como variável independente. Para a estimativa do volume comercial a partir da variável independente Dtoco o modelo indicado também foi o de simples entrada de Husch (V = 0,002603 * DAP^1,761132) (R²ajust. = 0,789 e Syx = 1,93 m³). Entretanto, em áreas que possuam tocos juntamente com as árvores abatidas, o modelo de dupla entrada de Schumacher e Hall (V = 0,000263 * Dtoco^1,782244 * Hc^0,765729 ) também pode ser utilizado uma vez que apresentou as melhores estatísticas dentre todos os modelos testados com estas variáveis (R²ajust. = 0,872 e Syx = 1,51 m³). Na ZF-2 o modelo de Husch (V= 0,000320 * DAP^2,242681) por apresentar indicadores robustos (R²ajust. = 0,975 e Syx = 0,07 m³) e não possuir a altura comercial como variável independente, devido ao elevado erro do tipo não amostral associado aos seus valores, é o mais indicado para estimar o volume de madeira para o gênero Eschweilera. Com relação ao modelo que utiliza o fator de forma médio conclui-se que este não é o método mais preciso para se estimar o volume de madeira em ambas as áreas de estudo. Esta forma de cálculo é predominante em Rorainópolis e tem estreita relação com o desmatamento ilegal, uma vez que nos inventários florestais a variável Hc presente neste modelo, é superestimada de forma induzida, o que acarreta em um maior erro do tipo não amostral

Development of a portable leaf photosynthesis and volatile organic compounds emission system

Understanding how plant carbon metabolism responds to environmental variables such as light is central to understanding ecosystem carbon cycling and the production of food, biofuels, and biomaterials. Here, we couple a portable leaf photosynthesis system to an autosampler for volatile organic compounds (VOCs) to enable field observations of net photosynthesis simultaneously with emissions of VOCs as a function of light. Following sample collection, VOCs are analyzed using automated thermal desorption-gas chromatograph-mass spectrometry (TD-GC–MS). An example is presented from a banana plant in the central Amazon with a focus on the response of photosynthesis and the emissions of eight individual monoterpenes to light intensity. Our observations reveal that banana leaf emissions represent a 1.1 +/- 0.1% loss of photosynthesis by carbon. Monoterpene emissions from banana are dominated by trans-β-ocimene, which accounts for up to 57% of total monoterpene emissions at high light. We conclude that the developed system is ideal for the identification and quantification of VOC emissions from leaves in parallel with CO2 and water fluxes.The system therefore permits the analysis of biological and environmental sensitivities of carbon metabolism in leaves in remote field locations, resulting in the emission of hydrocarbons to the atmosphere. • A field-portable system is developed for the identification and quantification of VOCs from leaves in parallel with leaf physiological measurements including photosynthesis and transpiration. • The system will enable the characterization of carbon and energy allocation to the biosynthesis and emission of VOCs linked with photosynthesis (e.g. isoprene and monoterpenes) and their biological and environmental sensitivities (e.g. light, temperature, CO2). • Allow the development of more accurate mechanistic global VOC emission models linked with photosynthesis, improving our ability to predict how forests will respond to climate change. It is our hope that the presented system will contribute with critical data towards these goals across Earth's diverse tropical forests. © 202

Demonstration of a strict molecular oxygen requirement of yellow latex oxidation in the central Amazon canopy tree muiratinga (Maquira sclerophylla (Ducke) C.C. Berg)

Plant-derived latex is widely used in rubber production and plays important roles in ecological processes in the tropics. Although it is known that latex oxidation from the commercially important tree Hevea brasiliensis, results in latex browning, little is known about latex oxidation in highly diverse tropical ecosystems. Here we show that upon physical trunk damage, yellow latex released from the canopy tree Muiratinga (Maquira sclerophylla (Ducke) C.C. Berg) is rapidly and extensively oxidized to a black resin in the presence of air within 15-30 min. In a nitrogen atmosphere, latex oxidation was inhibited, but was immediately activated upon exposure to air. The results suggest the occurrence of O2-dependent oxidative enzymes including polyphenol oxidase (PPO) within the latex of Muiratinga and supports previous findings of a key role of oxidation during latex coagulation. © 2018 Secretaria Regional do Rio de Janeiro da Sociedade Brasileira de Quimica.All right reserved

Tree climbing techniques and volume equations for Eschweilera (Matá-Matá), a hyperdominant genus in the Amazon Forest

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

Volatile monoterpene ‘fingerprints’ of resinous Protium tree species in the Amazon rainforest

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 Author

Below versus above ground plant sources of abscisic acid (ABA) at the heart of tropical forest response to warming

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios. © 2018 by the authors. Licensee MDPI, Basel, Switzerland

Soil fertility and drought interact to determine large variations in wood production for a hyperdominant Amazonian tree species

Introduction: The productivity of the Amazon Rainforest is related to climate and soil fertility. However, the degrees to which these interactions influence multiannual to decadal variations in tree diameter growth are still poorly explored. Methods: To fill this gap, we used radiocarbon measurements to evaluate the variation in tree growth rates over the past decades in an important hyperdominant species, Eschweilera coriacea (Lecythidaceae), from six sites in the Brazilian Amazon that span a range of soil properties and climate. Results: Using linear mixed-effects models, we show that temporal variations in mean annual diameter increment evaluated over a specific time period reflect interactions between soil fertility and the drought index (SPEI-Standardized Precipitation and Evapotranspiration Index). Discussion: Our results indicate that the growth response of trees to drought is strongly dependent on soil conditions, a facet of forest productivity that is still underexplored, and which has great potential for improving predictions of future tropical tree growth in the face of projected climate change

Green leaf volatile emissions during high temperature and drought stress in a central Amazon rainforest

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. © 2015 by the authors; licensee MDPI, Basel, Switzerland

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat