Nicheâ based processes outperform neutral processes when predicting distance decay in coâ dominance along the Amazon â Andes rainforest gradient

QuestionDispersal limitation (neutral hypothesis) and deterministic factors (niche hypothesis) shape floristic gradients including betweenâ site patterns of speciesâ dominance (coâ dominance). Because their relative importance remains poorly known, we ask how their comparative contribution to coâ dominance changes with elevation and geographical extent.LocationMadidi region, NW Bolivia.MethodsWe analysed floristic composition and environmental factors of 90 plots spanning the gradient from Amazonian (<1,000 m) to montane forests at three elevations (1,200â 1,500; 2,000â 2,300; and 2,800â 3,200 m) and two geographical extents: local (plots <12 km apart) and regional (38â 120 km apart). We modelled distance decay within each elevational band with a neutral model, using two parameters (speciation rate and dispersal distance). Subsequently, we related the model’s residuals to environmental differences using flexible machine learning models.ResultsWe found that 5â 44% of the variability in floristic differences along the gradient studied can be explained by a neutral model of distance decay, while 18â 50% can be explained by environmental differences. Montane forests showed an overall gradient in floristic composition that is congruent with an increase in elevation for both dispersal limitation and environmental filtering. However, Amazonian forest was more nicheâ structured and more dispersalâ limited relative to its elevation and topography.ConclusionsEnvironmental differences explained floristic differences better than the neutral model, even giving preferential attribution to the more parsimonious neutral processes.We analysed 90 tree communities spanning the longest forested elevational gradient on Earth: the extraordinarily diverse Amazonian and Andean forests of the Madidi region (Bolivia). Dominant species vary more with greater barriers to dispersal and stronger environmental changes, increasingly so at higher elevations. Amazonian dominant species, however, change more than expected at their elevation and topography.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149700/1/jvs12761-sup-0003-AppendixS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149700/2/jvs12761-sup-0001-AppendixS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149700/3/jvs12761.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149700/4/jvs12761_am.pd

Insights on biodiversity drivers to predict species richness in tropical forests at the local scale

Disentangling the relative importance of different biodiversity drivers (i.e., climate, edaphic, historical factors, or human impact) to predict plant species richness at the local scale is one of the most important challenges in ecology. Biodiversity modelling is a key tool for the integration of these drivers and the predictions generated are essential, for example, for climate change forecast and conservation planning. However, the reliability of biodiversity models at the local scale remains poorly understood, especially in tropical species-rich areas, where they are required. We inventoried all woody plants with stems ≥ 2.5 cm in 397 plots across the Andes-Amazon gradient. We generated and mapped 19 uncorrelated biodiversity drivers at 90 m resolution, grouped into four categories: microclimatic, microtopographic, anthropic, and edaphic. In order to evaluate the importance of the different categories, we grouped biodiversity drivers into four different clusters by categories. For each of the four clusters of biodiversity drivers, we modelled the observed species richness using two statistical techniques (random forest and Bayesian inference) and two modelling procedures (including or excluding a spatial component). All the biodiversity models produced were evaluated by cross-validation. Species richness was accurately predicted by random forest (Spearman correlation up to 0.85 and explained variance up to 67%). The results suggest that precipitation and temperature are important driving forces of species richness in the region. Nonetheless, a spatial component should be considered to properly predict biodiversity. This could reflect macroevolutionary underlying forces not considered here, such as colonization time, dispersal capacities, or speciation rates. However, the proposed biodiversity modelling approach can predict accurately species richness at the local scale and detailed resolution (90 m) in tropical areas, something that previous works had found extremely challenging. The innovative methodology presented here could be employed in other areas with conservation needsWe thank the Consejería de Educacion (Comunidad de Madrid, Spain), National Geographic Society (8047-06, 7754-04), National Science Foundation (DEB#0101775, DEB#0743457, DEB#1557094), Spanish Ministry of Economy and Competitiveness (CGL2016-75414-P), Centro de Estudios de América Latina (Universidad Autonoma de Madrid – Banco Santander), Consejería de Educacion, Cultura y Deportes (Junta de Comunidades de Castilla-La Mancha, SBPLY/21/180501/000241), Spanish Ministry of Economy and Competitiveness (PID2019-106341GB-I00) for funding our research. The full dataset can be requested from the Madidi Project (https://madidiproject.weebly.com/

Trade-offs among aboveground, belowground, and soil organic carbon stocks along altitudinal gradients in Andean tropical montane forests

Tropical montane forests (TMFs) play an important role as a carbon reservoir at a global scale. However, there is a lack of a comprehensive understanding on the variation in carbon storage across TMF compartments [namely aboveground biomass (AGB), belowground biomass (BGB), and soil organic matter] along altitudinal and environmental gradients and their potential trade-offs. This study aims to: 1) understand how carbon stocks vary along altitudinal gradients in Andean TMFs, and; 2) determine the influence of climate, particularly precipitation seasonality, on the distribution of carbon stocks across different forest compartments. The study was conducted in sixty 0.1 ha plots along two altitudinal gradients at the Podocarpus National Park (Ecuador) and Río Abiseo National Park (Peru). At each plot, we calculated the amount of carbon in AGB (i.e. aboveground carbon stock, AGC), BGB (i.e. belowground carbon stock, BGC), and soil organic matter (i.e. soil organic carbon stock, SOC). The mean total carbon stock was 244.76 ± 80.38 Mg ha–1 and 211.51 ± 46.95 Mg ha–1 in the Ecuadorian and Peruvian plots, respectively. Although AGC, BGC, and SOC showed different partitioning patterns along the altitudinal gradient both in Ecuador and Peru, total carbon stock did not change with altitude in either site. The combination of annual mean temperature and precipitation seasonality explained differences in the observed patterns of carbon stocks across forest compartments between the two sites. This study suggests that the greater precipitation seasonality of colder, higher altitudes may promote faster turnover rates of organic matter and nutrients and, consequently, less accumulation of SOC but greater AGC and BGC, compared to those sites with lesser precipitation seasonality. Our results demonstrate the capacity of TMFs to store substantial amounts of carbon and suggest the existence of a trade-off in carbon stocks among forest compartments, which could be partly driven by differences in precipitation seasonality, especially under the colder temperatures of high altitudesAuthorizations to work in protected areas were granted by national authorities: Ecuador (MAE-DNB-CM2015-0016) and Perú (001-2016-SERNANP-PNRA-JEF

Estudio de la contaminación por metales pesados en suelos y plantas de la Vega de Aranjuez. Posible impacto por efecto de las aguas de riego

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Geología y Geoquímica. Fecha de lectura 23-05-198

Geochemistry and mineralogy of surface pyritic tailings impoundments at two mining sites of the Iberian Pyrite Belt (SW Spain)

Two pyritic tailings impoundments located in two mining areas of the Iberian Pyrite Belt (Cueva de la Mora and Minas de Rı´otinto-Zarandas) were selected to asses their potential environmental impact. Mineralogical (XRD diffraction study), physico-chemical characterization (colour, particle size, pH, acid–base account, total Fe, As, Cu, Pb and Zn) as well as a speciation study (by means of a seven-step sequential extraction procedure) were performed in superficial (0–20 cm) tailings samples. Arsenic and metal contents in soils around the tailings impoundments were also studied. Zarandas dam, a reclaimed impoundment, which has been limed, partially topsoiled and planted, has supported and allowed the growth of pine trees and other plants for many years. The surface of this impoundment can be considered very acid but nonacid forming. Although total As and metal concentrations were relatively high, it is not possible to conclude that the Zarandas tailings have polluted the surrounding soils. Tailings in Cueva de la Mora showed high total and easily mobilizable concentration of toxic elements. The net neutralization potential was strongly negative as a consequence of the acid generation caused by the sulphide oxidation, the presence of secondary acid-generating minerals and the absence of neutralizing materials. Coquimbite and rhomboclase efflorescences formed during the Mediterranean dry summers on the surface of this impoundment contained very high levels of soluble As, Cu and Zn that were easily dissolved and released to the running water in the first rains of autumnDepartamento de Investigación en Recursos Geológicos, Instituto Geológico y Minero de España, EspañaDepartamento de Geología y Geoquímica, Universidad Autónoma de Madrid, EspañaDepartamento de Investigación y Prospectiva Geocientífica, Instituto Geológico y Minero de España, Españ

Recuperación de Cobre a partir de Eflorescencias Salinas Procedentes de Residuos Mineros

Congreso Nacional de Geoquímica (12º. 2017. Linares, Jaén). Congreso Ibérico de Geoquímica (11º. 2017. Linares, Jaén)En el presente trabajo se estudian las características químicas y mineralógicas de las eflorescencias salinas que aparecen anualmente en una zona próxima al río Tinto en la localidad de Nerva (Huelva) así como de los sustratos subsuperficiales ubicados debajo de ellas. Se han distinguido dos tipos de eflorescencias. Las más ácidas y alejadas del cauce del río, con una tasa de producción de aproximadamente160 t/ha llegan a presentar valores de pH negativo, están compuestas principalmente de coquimbita y magnesiocopiapita, y presentan los mayores contenidos en Fe. Las más cercanas al río, todavía en fase de formación en el mes de julio, con una producción aproximada de 28 t/ha, son más ricas en Al y Mg siendo sus minerales representativos rozenita, pickeringita y copiapita. En ambos tipos de eflorescencias aparecen elevados contenidos de elementos traza, destacando Cu y Zn con contenidos comprendidos entre 4500 y5600 mg/kg. Se ha realizado una experiencia de laboratorio de cementación de cobre sobre lámina de hierro encaminada a evaluar la posibilidad de recuperación espontánea del cobre disuelto en el extracto acuoso de las eflorescencias en relación 10L/kg. En dicho proceso se ha observado una rápida cinética de reacción con una progresiva disminución de cobre y aumento de hierro en el extracto situado próximo a la lámina, mientras que los contenidos en Zn en el extracto no mostraban modificaciones significativas.Instituto Geológico y Minero de España, EspañaUniversidad de Cádiz, Españ

Acoso sexual en la comunidad estudiantil de la Universidad de Manizales (Colombia) 2008: Estudio de corte transversal Sexual harassment in the University of Manizales' student community. (Colombia), 2008: A cross-sectional study

Introducción: el objetivo de la presente investigación es analizar el acoso sexual, su frecuencia e imaginarios en la comunidad estudiantil de la Universidad de Manizales, Caldas (Colombia). Esta es una temática con escasas investigaciones en el ámbito universitario y con importantes implicaciones para la víctima. Metodología: este estudio de corte transversal se efectúo con 205 estudiantes de la Universidad de Manizales, muestra representativa de una población de 3.584 personas. Entre otras variables, se indagó sobre el acoso sexual antes y después de ingresar a la universidad, quién efectuó el acoso, la opinión de los estudiantes sobre qué se considera un acoso sexual, quién lo propicia y cómo debe ser castigado; así como la orientación sexual, la facultad y el semestre al que pertenecía el estudiante. Resultados: se observó una frecuencia de acoso sexual de 6,8% durante la permanencia en la universidad, la cual se presentó únicamente en los 4 primeros semestres y fue efectuada por docentes (50%) y compañeros de clase (21,4%, hombres y mujeres en la misma proporción). De manera adicional, sólo 7,1% de los casos fue denunciado y de éstos únicamente 66,7% recibió ayuda. En contraste, 47,1% de los acosados ha sido víctima de chantaje e intimidación para evitar que denuncie. Sin embargo, 23,5% de las víctimas consideran que en parte propiciaron el acoso. Conclusiones: el acoso sexual es una agresión a los derechos fundamentales y está ahora presente en la Universidad de Manizales. No osbstante, aunque no tiene una frecuencia tan alta comparado con otros estudios, sí constituye un problema en el cual se debe intervenir.Introduction: this investigation was aimed at analysing sexual harassment, its frequency and images amongst the student community at the University of Manizales, Caldas, Colombia. This topic has not been researched in depth in the Colombian university environment but implies great repercussions for the victims. Methodology: this was a cross-sectional study which was carried out on a representative sample of 203 students from a total of 3,584 students from the University of Manizales (Colombia). The variables studied here considered questions such as experiencing sexual harassment before and after entering university, by whom the harassment was made, opinions about what is considered to be sexual harassment, who did it and how it should be punished. Sexual orientation was also questioned, as were the faculty and semester to which a particular student belonged. Results: a 6.8% frequency of sexual harassment was found during stay at university; this was found only during the first 4 semesters, mostly being committed by teachers (50%) and classmates (21.4%, male and female in the same ratio). Only 7.1% denounced such harassment and only 66.7% of this number obtained any help. 47.1% had been the victims of blackmail and intimidation to keep them from denouncing such abuse. 23.5% consider that they were partly to blame for the harassment. Conclusions: sexual harassment is an assault on fundamental rights and is present in the University of Manizales. Even though its frequency is not so high when compared to other studies, it constitutes a problem in which university authorities should become involved