Height-diameter allometry of tropical forest trees

Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account. © 2011 Author(s)

The Amazon Tall Tower Observatory (ATTO): Overview of pilot measurements on ecosystem ecology, meteorology, trace gases, and aerosols

The Amazon Basin plays key roles in the carbon and water cycles, climate change, atmospheric chemistry, and biodiversity. It has already been changed significantly by human activities, and more pervasive change is expected to occur in the coming decades. It is therefore essential to establish long-term measurement sites that provide a baseline record of present-day climatic, biogeochemical, and atmospheric conditions and that will be operated over coming decades to monitor change in the Amazon region, as human perturbations increase in the future. The Amazon Tall Tower Observatory (ATTO) has been set up in a pristine rain forest region in the central Amazon Basin, about 150 km northeast of the city of Manaus. Two 80 m towers have been operated at the site since 2012, and a 325 m tower is nearing completion in mid-2015. An ecological survey including a biodiversity assessment has been conducted in the forest region surrounding the site. Measurements of micrometeorological and atmospheric chemical variables were initiated in 2012, and their range has continued to broaden over the last few years. The meteorological and micrometeorological measurements include temperature and wind profiles, precipitation, water and energy fluxes, turbulence components, soil temperature profiles and soil heat fluxes, radiation fluxes, and visibility. A tree has been instrumented to measure stem profiles of temperature, light intensity, and water content in cryptogamic covers. The trace gas measurements comprise continuous monitoring of carbon dioxide, carbon monoxide, methane, and ozone at five to eight different heights, complemented by a variety of additional species measured during intensive campaigns (e.g., VOC, NO, NO2, and OH reactivity). Aerosol optical, microphysical, and chemical measurements are being made above the canopy as well as in the canopy space. They include aerosol light scattering and absorption, fluorescence, number and volume size distributions, chemical composition, cloud condensation nuclei (CCN) concentrations, and hygroscopicity. In this paper, we discuss the scientific context of the ATTO observatory and present an overview of results from ecological, meteorological, and chemical pilot studies at the ATTO site. © Author(s) 2015

Caracterización de la fibrilación auricular en el Servicio de Medicina Interna del Hospital Nacional San Rafael (El Salvador)

Introduction: Atrial fibrillation is a serious health problem. Central American countries are not exempt from this scourge.Objective: To characterize atrial fibrillation, specify its clinical and epidemiological variables and determine stroke risks by using CHA2DS2-VASc score.Method: A descriptive and prospective study was carried out on 107 patients admitted with diagnosis of atrial fibrillation, in the Department of Internal Medicine at “Hospital Nacional San Rafael” from Santa Tecla city, La Libertad, El Salvador, from January to July 2013. The clinical and epidemiological variables were analyzed, an echocardiogram was performed on all patients and CHA2DS2-VASc risk score was calculated. Methods were used to establish the relationships betweenvariables.Results: More than half of atrial fibrillation patients (57.0%; p=0.015) are women, 51.4% white and the average age is 74.7 ± 13.8 years. 80.4% of patients have non-valvular atrial fibrillation. There was hypertension prevalence (54.2%), ischemic heart disease (28.0%), hypertensive (23.4%) and dilated cardiomyopathies (24.3%), and permanent atrial fibrillation (49.5%). The left atrium average size was 42.67 ± 8.2 mm. The lower ejection fraction (p=0.012) and increased left ventricular diastolic diameter (p=0.004) showed significant relationship with the occurrence of non-valvular atrial fibrillation. 84.9% of patients have a high risk of stroke according to CHA2DS 2-VASc score. Age older than 75 years (p <0.001), between 65 and 74 (p=0.025), female sex (p=0.001) and increased thickness of the interventricular septum (p=0.006) were associated with higher risk.Conclusions: The lower ejection fraction and increased left ventricular diastolic diameter were associated with atrial fibrillation. Most patients have a high risk of stroke; variables associated are older age, female gender and increased thickness of the interventricular septum.Introducción: La fibrilación auricular es un serio problema de salud y los países centroamericanos no escapan de este flagelo.Objetivo: Caracterizar la fibrilación auricular, precisar sus variables clínico-epidemiológicas y determinar el riesgo de accidente cerebrovascular, a partir del uso de la escala CHA2DS2-VASc.Método: Se realizó un estudio descriptivo y prospectivo en 107 pacientes que ingresaron, con diagnóstico de fibrilación auricular, en el servicio de Medicina Interna del Hospital Nacional San Rafael de la ciudad de Santa Tecla, La Libertad, El Salvador; en el período de enero a julio de 2013. Se analizaron las variables clínico-epidemiológicas, se realizó ecocardiograma a todos los pacientes y se calculó la escala de riesgo CHA2DS2-VASc. Se utilizaron métodos para establecer las relaciones entre las variables.Resultados: Más de la mitad de los pacientes con fibrilación auricular (57,0 %; p= 0,015) son mujeres, el 51,4 % tiene color blanco de piel y una edad media de 74,7 ± 13,8 años. El 80,4 % de los pacientes tiene una fibrilación auricular no asociada a valvulopatía. Predominaron la hipertensión arterial (54,2 %), las cardiopatías isquémica (28,0 %) e hipertensiva (23,4 %), la miocardiopatía dilatada (24,3 %) y la fibrilación auricular permanente (49,5 %). La media del tamaño de la aurícula izquierda fue de 42,67 ± 8,2 mm. La menor fracción de eyección (p=0,012) y el mayor diámetro diastólico del ventrículo izquierdo (p=0,004) mostraron relación significativa con la aparición de fibrilación auricular de origen no valvular. El 84,9 % de los pacientes tiene alto riesgo de ACV según el puntaje de CHA2DS2-VASc. La edad mayor de 75 años (p<0,001), de 65-74 (p=0,025), el sexo femenino (p=0,001) y el mayor grosor del septum interventricular (p=0,006), se asociaron al mayor riesgo.Conclusiones: La menor fracción de eyección y el mayor diámetro diastólico del ventrículo izquierdo se relacionaron con la fibrilación auricular. La mayoría de los pacientes presenta un riesgo elevado de accidente cerebrovascular, las variables que se le asocian son: la mayor edad, el sexo femenino y el mayor grosor del septum interventricular

Characterization of atrial fibrillation in the Department of Internal Medicine at “Hospital Nacional San Rafael” (El Salvador)

Introduction: Atrial fibrillation is a serious health problem. Central American countries are not exempt from this scourge. Objective: To characterize atrial fibrillation, specify its clinical and epidemiological variables and determine stroke risks by using CHA2DS2-VASc score. Method: A descriptive and prospective study was carried out on 107 patients admitted with diagnosis of atrial fibrillation, in the Department of Internal Medicine at “Hospital Nacional San Rafael” from Santa Tecla city, La Libertad, El Salvador, from January to July 2013. The clinical and epidemiological variables were analyzed, an echocardiogram was performed on all patients and CHA2DS2-VASc risk score was calculated. Methods were used to establish the relationships between variables. Results: More than half of atrial fibrillation patients (57.0%; p=0.015) are women, 51.4% white and the average age is 74.7 ± 13.8 years. 80.4% of patients have non-valvular atrial fibrillation. There was hypertension prevalence (54.2%), ischemic heart disease (28.0%), hypertensive (23.4%) and dilated cardiomyopathies (24.3%), and permanent atrial fibrillation (49.5%). The left atrium average size was 42.67 ± 8.2 mm. The lower ejection fraction (p=0.012) and increased left ventricular diastolic diameter (p=0.004) showed significant relationship with the occurrence of non-valvular atrial fibrillation. 84.9% of patients have a high risk of stroke according to CHA2DS 2-VASc score. Age older than 75 years (p <0.001), between 65 and 74 (p=0.025), female sex (p=0.001) and increased thickness of the interventricular septum (p=0.006) were associated with higher risk. Conclusions: The lower ejection fraction and increased left ventricular diastolic diameter were associated with atrial fibrillation. Most patients have a high risk of stroke; variables associated are older age, female gender and increased thickness of the interventricular septum

ESICM LIVES 2016: part two : Milan, Italy. 1-5 October 2016.

Meeting abstrac