1,720,964 research outputs found
Los indígenas y la pérdida de la biodiversidad. Estereotipos, papeles y responsabilidades ante la crisis ambiental
No full textSe revisa la relación existente entre los tsotsiles del municipio de Huixtán con sus bosques, intentando ejemplificar la variedad de circunstancias en que sucede la degradación ambiental y planteando la importancia de un abordaje multidisciplinario en las áreas indígenas, cultural y biológicamente diversas
Factors affecting variation in forest community cgaracteristics and leaf-litter decomposition in tropical montane forest of Chiapas, Mexico: a functional ecology approach
No full textA functional ecology approach was combined with floristic studies to seek increased ecological understanding of forest characteristics and processes in the Central Highlands of Chiapas State, Mexico. The study had two main aims: 1) to determine the major ecological factors driving the floristic and functional variation of forest ecosystems, with emphasis on the operation of either environmental (niche model) or spatial (dispersal limitation model) factors and 2) to determine the relationship of leaf-litter decomposition rates to both leaf functional traits and forest conditions. For this, the specific objectives were i), characterise both the dominant species and the forest stands they form using functional traits, determining also the trait-trait and species-trait relationships; ii), characterise the floristic and functional variation amongst forest stands, and the relationship of this variation with spatial and environmental variables; iii) determine the influence of spatial factors, climate variables, anthropogenic disturbance, forest canopy openness and the traits of species on the abundance of saplings and iv), determine the effect of species leaf trait values, forest type, and their interaction, on leaf-litter decomposition. The study area encompassed a narrow altitudinal range from 2100 to 2800 m a.s.l., located on a carboniferous limestone substrate with abrupt topography and a cool and humid climate. For objectives i), ii) and iii), both adult trees and saplings were counted, measured and identified in field plots in four previously-defined forest types –oak forest, pine-oak forest, pine forest and broadleaved forest– at seven study sites. Plots were characterised in terms of spatial location, altitude above sea level and climate variables from Worldclim climate surfaces. Leaf, stem and whole-plant traits, as well as leaf carbon fractions, were measured for dominant species, and saplings were sampled under both closed and open canopies. For objective iv), first, leaf litter decomposition rates of 20 dominant species were measured in a greenhouse experiment for the assessment of trait effects and second, decomposition rates of representative litter from each forest type, plus two standard species, were measured in a field experiment using forest type as the main factor. Forests of the study area are a mosaic in which three main functional groups of species were identified (objective i). Two groups were respectively dominated by Quercus species and Pinus species, which both reach the canopy or sub-canopy layers of the forests and had high wood density, leaf dry matter content (LDMC) and other trait values suggesting relatively slow growth. The third group contained a wide taxonomic range of species that generally develop in the forest understorey and had high specific leaf area, leaf nutrient contents and other trait values suggesting relatively high rates of growth and population turnover. These three functional groups of species form a variety of floristic assemblages, ranging from those of simple structure and low floristic diversity (mostly pine forests) to complex and diverse broad-leaved forests. Most oak and pine-oak forests had intermediate characteristics. Variation partitioning analysis showed that the floristic variation of both adults and saplings was related to climate but also to spatial factors, suggesting an important role of dispersal limitation in the shaping of species assemblages (objectives ii and iii). In contrast, variation partitioning also showed that forest functional characteristics –measured using weighted mean trait values– were strongly linked to human disturbance, suggesting that people have had strong effects on the ecological functions of these forests (objective ii). Additionally, floristic variation among forest stands was not always accompanied by functional variation, suggesting that floristics can change across space while forest functional characteristics remain relatively homogeneous. Regarding objective (iii), leaf area was the only species functional trait with a clear relationship to the absolute densities of saplings, suggesting that the abundance of regeneration increases with increasing leaf area, though the effect of canopy openness was small. Finally, for objective iv), the greenhouse experiment showed that Quercus spp. and Pinus spp. with tough leaves had relatively slow decomposition rates and species with lower LDMC and associated tradeoffs in trait values, such as high specific leaf area, had higher decomposition rates. In the field experiment (objective iv), decomposition rates did not vary significantly between the four different forest types, supporting the hypothesis that persistent leaf characteristics of species, rather than forest functional characteristics and environment, are the most important controls on decomposition. Nevertheless, there was evidence that litter mixtures tended to show higher decomposition rates in forest associations where they were collected, than in other forest associations (the “home-field advantage” hypothesis). This result suggests probable variations in leaf-litter substrates determined by forest functional composition. It is believed that this is the first study to apply a functional traits approach to understanding variation of forest ecological characteristics and processes in Mesoamerican mountains. The study shows that dispersal limitation, as well as environmental and anthropogenic factors, probably influences the characteristics of forest stands, and that the degree of functional variation may be smaller than that of floristic variation. The study demonstrates that leaf trait values of dominant tree species influence litter decomposition rates and therefore, potentially, nutrient cycling. Even though litter decomposition rates in the field were most likely to be affected by leaf and litter characteristics, not forest environment, there was evidence for a home-field advantage effect. In the current era of anthropogenic global change effects on the forests of Chiapas, this work sheds new light on forest function and forest change and has special relevance for the design of conservation strategies for the tropical montane ecosystems
Factors affecting variation in forest community characteristics and leaf-litter decomposition in tropical montane forest of Chiapas, Mexico: a functional ecology approach
No full textTesis (doctorado) -- CATIE. Escuela de Posgrado. Turrialba (Costa Rica) ; Bangor University, Bangor (Reino Unido), 2016A functional ecology approach was combined with floristic studies to seek increased ecological understanding of forest characteristics and processes in the Central Highlands of Chiapas State, Mexico. The study had two main aims: 1) to determine the major ecological factors driving the floristic and functional variation of forest ecosystems, with emphasis on the operation of either environmental (niche model) or spatial (dispersal limitation model) factors and 2) to determine the relationship of leaf-litter decomposition rates to both leaf functional traits and forest conditions. For this, the specific objectives were i), characterise both the dominant species and the forest stands they form using functional traits, determining also the trait-trait and species-trait relationships; ii), characterise the floristic and functional variation amongst forest stands, and the relationship of this variation with spatial and environmental variables; iii) determine the influence of spatial factors, climate variables, anthropogenic disturbance, forest canopy openness and the traits of species on the abundance of saplings and iv), determine the effect of species leaf trait values, forest type, and their interaction, on leaf-litter decomposition. The study area encompassed a narrow altitudinal range from 2100 to 2800 m a.s.l., located on a carboniferous limestone substrate with abrupt topography and a cool and humid climate. For objectives i), ii) and iii), both adult trees and saplings were counted, measured and identified in field plots in four previously-defined forest types –oak forest, pine-oak forest, pine forest and broadleaved forest– at seven study sites. Plots were characterised in terms of spatial location, altitude above sea level and climate variables from Worldclim climate surfaces. Leaf, stem and whole-plant traits, as well as leaf carbon fractions, were measured for dominant species, and saplings were sampled under both closed and open canopies. For objective iv), first, leaf litter decomposition rates of 20 dominant species were measured in a greenhouse experiment for the assessment of trait effects and second, decomposition rates of representative litter from each forest type, plus two standard species, were measured in a field experiment using forest type as the main factor. Forests of the study area are a mosaic in which three main functional groups of species were identified (objective i). Two groups were respectively dominated by Quercus species and Pinus species, which both reach the canopy or sub-canopy layers of the forests and had high wood density, leaf dry matter content (LDMC) and other trait values suggesting relatively slow growth. The third group contained a wide taxonomic range of species that generally develop in the forest understorey and had high specific leaf area, leaf nutrient contents and other trait values suggesting relatively high rates of growth and population turnover. These three functional groups of species form a variety of floristic assemblages, ranging from those of simple structure and low floristic diversity (mostly pine forests) to complex and diverse broad-leaved forests. Most oak and pine-oak forests had intermediate characteristics. Variation partitioning analysis showed that the floristic variation of both adults and saplings was related to climate but also to spatial factors, suggesting an important role of dispersal limitation in the shaping of species assemblages (objectives ii and iii). In contrast, variation partitioning also showed that forest functional characteristics –measured using weighted mean trait values– were strongly linked to human disturbance, suggesting that people have had strong effects on the ecological functions of these forests (objective ii). Additionally, floristic variation among
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forest stands was not always accompanied by functional variation, suggesting that floristics can change across space while forest functional characteristics remain relatively homogeneous. Regarding objective (iii), leaf area was the only species functional trait with a clear relationship to the absolute densities of saplings, suggesting that the abundance of regeneration increases with increasing leaf area, though the effect of canopy openness was small. Finally, for objective iv), the greenhouse experiment showed that Quercus spp. and Pinus spp. with tough leaves had relatively slow decomposition rates and species with lower LDMC and associated tradeoffs in trait values, such as high specific leaf area, had higher decomposition rates. In the field experiment (objective iv), decomposition rates did not vary significantly between the four different forest types, supporting the hypothesis that persistent leaf characteristics of species, rather than forest functional characteristics and environment, are the most important controls on decomposition. Nevertheless, there was evidence that litter mixtures tended to show higher decomposition rates in forest associations where they were collected, than in other forest associations (the “home-field advantage” hypothesis). This result suggests probable variations in leaf-litter substrates determined by forest functional composition. It is believed that this is the first study to apply a functional traits approach to understanding variation of forest ecological characteristics and processes in Mesoamerican mountains. The study shows that dispersal limitation, as well as environmental and anthropogenic factors, probably influences the characteristics of forest stands, and that the degree of functional variation may be smaller than that of floristic variation. The study demonstrates that leaf trait values of dominant tree species influence litter decomposition rates and therefore, potentially, nutrient cycling. Even though litter decomposition rates in the field were most likely to be affected by leaf and litter characteristics, not forest environment, there was evidence for a home-field advantage effect. In the current era of anthropogenic global change effects on the forests of Chiapas, this work sheds new light on forest function and forest change and has special relevance for the design of conservation strategies for the tropical montane ecosystems.CATIE (Centro Agronómico Tropical de Investigación y Enseñanza
De bosques y saberes. Perspectivas de conservación de recursos forestales en el municipio de Huixtán, Chiapas
No full textTesis de maestría en ciencias sociales con opción en estudios fronterizo
Presentación
No full textLos autores de los cuatro artículos que dan inicio a este número de la revista Pueblos y fronteras digital se ocupan de temas contrastantes del estado de Chiapas y del sureste mexicano. En el primero, «Pueblo trágico: gubernamentalidad neoliberal y multicultural en el sureste mexicano», Sandra Cañas muestra la forma en que un programa gubernamental como el de «Pueblos mágicos» aboga por la inclusión multicultural pero desde una lógica mercantilista en la que sectores de población, particularmente indígenas, permanecen excluidos, sin poder de decisión, obteniendo minúsculos y muy cuestionables beneficios. ..
Sobre la etnobiología y sus marcos de trabajo en México. Comentarios al libro editado por Nemer Narchi Narchi y Felipe Ruan Soto
Full text linkThis document presents a review of Etnobiología a la mexicana. Métodos, consejos y lineamientos selectos del campo, edited by Nemer Narchi Narchi and Felipe Ruan Soto, a book whose main objective is to present general frameworks for ethnobiological work both in the field and in office settings. The book, the result of the compilation of 13 chapters written by 28 authors who have practiced their profession in Mexico, addresses and explores a wide range of ethnobiological subdisciplines.Se presenta una revisión del libro Etnobiología a la mexicana. Métodos, consejos y lineamientos selectos del campo, editado por Nemer Narchi Narchi y Felipe Ruan Soto, obra cuyo objetivo principal es ofrecer marcos generales para la realización de trabajo etnobiológico tanto en campo como en gabinete. En el libro, resultado de la reunión de 13 capítulos escritos por 28 autoras y autores que han ejercido su profesión en México, se aborda y analiza una amplia variedad de subdisciplinas de la etnobiología
PRESENTACIÓN
Full text linkLos autores de los cuatro artículos que dan inicio a este número de la revista Pueblos y fronteras digital se ocupan de temas contrastantes del estado de Chiapas y del sureste mexicano. En el primero, «Pueblo trágico: gubernamentalidad neoliberal y multicultural en el sureste mexicano», Sandra Cañas muestra la forma en que un programa gubernamental como el de «Pueblos mágicos» aboga por la inclusión multicultural pero desde una lógica mercantilista en la que sectores de población, particularmente indígenas, permanecen excluidos, sin poder de decisión, obteniendo minúsculos y muy cuestionables beneficios. ..
Presentación
No full textEl área mesoamericana se constituye como puente y reservorio biofísico y cultural de importancia planetaria, sujeto a crecientes tensiones entre conservación y aprovechamiento de los recursos naturales, en un contexto de desigualdad social y política, así como de agravamiento de la crisis ambiental global. Dentro de este marco, el presente número de la Revista Pueblos y Fronteras Digital ofrece un conjunto de investigaciones realizadas en la región sureste de México, con temáticas, metodologías y perspectivas disciplinarias que exponen la complejidad del estudio de lo ambiental en interacción con lo social
HISTORIA DE LA TRADUCCIÓN. REFLEXIONES EN TORNO DEL LENGUAJE TRADUCTIVO DESDE LA ANTIGÜEDAD HASTA LOS CONTEMPORÁNEOS
Full text linkHistoria de la traducción. Reflexiones en torno del lenguaje traductivo desde la antigüedad hasta los contemporáneos, 2012, de Bruno Osimo, Paidós, México, 349 pp. ISBN 978-607-9202-31-
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