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5 resultados encontrados para: AUTOR: Méndez Dewar, Guadalupe
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1.
Tesis - Maestría
Contrastes espaciales de luz en claros, bordes y hábitats perturbados en Los Altos de Chiapas, México / Guadalupe Méndez Dewar
Méndez Dewar, Guadalupe ; González Espinosa, Mario (tutor) (1950-) ; Quintana Ascencio, Pedro F. (asesor) (1959-) ; Castellanos Albores, Jorge (asesor) ;
San Cristóbal de Las Casas, Chiapas, México : El Colegio de la Frontera Sur , 2000
Clasificación: TE/634.97 / M4
Cerrar
SIBE Campeche
ECO040001030 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Chetumal
ECO030000378 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
ECO010016428 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Tapachula
ECO020003065 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Villahermosa
ECO050001402 (Disponible)
Disponibles para prestamo: 1
Resumen en: Inglés |
Resumen en inglés

We evaluated the light conditions of points in small gaps (64-175 m2) and in surrounding forested areas with hemispheric photographs, and its relationship with growth variables in 605 transplanted individuals (2.5 x 3.0 m from each other) of five native tree species: Almis acuminata, Cornus excelsa, Liquidambar styraciflua, Persea americana and Ouercus laurina. We assumed that spatial light contrasts between open and forested habitats have decreased with recent rising of disturbance levels. Plant performance variables were related (after 15 months) to direct sunlight (RDS) al the transplant point, and with spatial light contrast indices (LCl) constructed with RDS values in neighboring points. Positive contrasts included relatively highlight points surrounded by shaded areas; negative constrasts represented shaded points in the middle of more illuminated spots. Study plots showed a large heterogeneity of light enviromiients. Highest negative contrasts occurred when RDS < 15%; an asymptote (LCl = 0) was associated to canopy openings with RDS> 35%. Multiple linear regression indicated that RDS was related to shoot height of Liquidambar (P < 0.007) after removing the effect of their initial measurements. With only negative contrast points in the regression, height was related to RDS in Alnus (P < 0.05), Cornus (P < 0.045), and Liquidambar (P < 0.009), and stem diameter in Persea (P < 0.041). Basal stem diameter in Liquidambar (P < 0.039) and leaf size in Ouercus (P < 0.002) were explained by RDS under positive contrasts. Taller and thicker plants of Ouercus (P < 0.016) were related to high contrasts under high-light conditions.

The results indicate that plant performance may depend on relative conditions of the light environment in addition to point-level values. Further criteria and indicators of forest sustainability and functional classification of tree species may consider the heterogeneity of light environments as represented by spatial light contrasts.


2.
Tesis
Crecimiento y supervivencia de árboles juveniles de cinco especies nativas en bosques perturbados en los Altos de Chiapas, México / Beatriz Adriana Pérez Espinosa
Pérez Espinosa, Beatriz Adriana (autora) ; González Espinosa, Mario (director) (1950-) ; González Esquinca, Alma Rosa (asesora) ; Méndez Dewar, Guadalupe (asesora) ;
Tuxtla Gutiérrez, Chiapas, México : Universidad de Ciencias y Artes de Chiapas. Escuela de Biología , 2006
Clasificación: TE/582.16097275 / P4
Cerrar
SIBE Campeche
ECO040002695 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Chetumal
ECO030004395 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
ECO010006437 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Villahermosa
ECO050002851 (Disponible)
Disponibles para prestamo: 1

3.
- Libro con arbitraje
Diversidad biológica en Chiapas / Mario González Espinosa, Neptalí Ramírez Marcial, Lorena Ruiz Montoya (coordinadores)
González Espinosa, Mario (coord.) (1950-) ; Ramírez Marcial, Neptalí (coord.) (1963-) ; Ruiz Montoya, Lorena (coord.) (1964-) ;
México : El Colegio de la Frontera Sur :: Consejo de Ciencia y Tecnología del Estado de Chiapas :: Plaza y Valdés , 2005
Clasificación: EE/333.9507275 / D5
Cerrar
SIBE Campeche
ECO040007010 (Disponible) , ECO040002410 (Disponible)
Disponibles para prestamo: 2
Cerrar
SIBE Chetumal
ECO030002871 (Disponible) , ECO030001436 (Disponible)
Disponibles para prestamo: 2
Cerrar
SIBE San Cristóbal
ECO010015400 (Disponible) , ECO010008908 (Disponible) , ECO010007827 (Disponible)
Disponibles para prestamo: 3
Cerrar
SIBE Tapachula
ECO020008674 (Disponible) , ECO020008822 (Disponible)
Disponibles para prestamo: 2
Cerrar
SIBE Villahermosa
ECO050004732 (Disponible) , ECO050002699 (Disponible)
Disponibles para prestamo: 2

4.
- Artículo con arbitraje
*En hemeroteca, SIBE-Tapachula
From seedling to sapling: tree species responses to spatial and temporal understory light heterogeneity in disturbed tropical montane forests
Méndez Dewar, Guadalupe ; González Espinosa, Mario (coaut.) (1950-) ; Equihua Zamora, Miguel (coaut.) ;
Contenido en: Botanical Sciences Vol. 93, no. 4 (2015), p. 719-729 ISSN: 2007-4298
Bibliotecas: Tapachula
Cerrar
SIBE Tapachula
56508-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Tapachula
PDF
Resumen en: Español | Inglés |
Resumen en español

Las dificultades para medir a pequeña escala la heterogeneidad de luz en el sotobosque se refleja en la clasificación de especies, convencionalmente basada en su respuesta al claro o a la sombra, condiciones rara vez uniformes en el espacio y el tiempo. La heterogeneidad espacial y temporal expresada por el contraste entre la luz directa sobre un área (luz vertical) y la luz sobre sus alrededores, permitirá mejorar la estimación del ambiente de luz del sotobosque y de la respuesta de las especies a sus variaciones. Analizamos con medidas repetidas el efecto de luz vertical, contraste y distancia al claro sobre el desempeño de plántulas trasplantadas de Alnus acuminata, Cornus excelsa, Liquidambar styracifl ua, Quercus laurina y Persea americana. Los Altos de Chiapas entre 1999 y 2005, en ocho parcelas de bosque de pino-encino, cada una con un claro central pequeño. Evaluamos la iluminación mediante fotografías hemisféricas al principio y al final del estudio. Se midió esbeltez y supervivencia a uno, dos, cuatro y seis años del trasplante. Distancia afectó la supervivencia de Alnus y Liquidambar. Luz vertical explicó esbeltez de Liquidambar. Contraste explicó esbeltez de Liquidambar, Cornus y Quercus y supervivencia de Liquidambar, Quercus y Persea, condicionada a la edad de la planta. La condición inicial de contraste inicial predijo la final, no así la luz vertical. El contraste entre dos gradientes del mismo recurso aumentó notablemente su poder predictivo sobre el desempeño de las especies al describir las pequeñas variaciones de luz en el sotobosque

Resumen en inglés

Difficulties in measuring small-scale light heterogeneity in forest understories is reflected in the classification of species, conventionally based on their responses to gaps or shade, rarely present in uniform conditions in space and time. Spatial and temporal heterogeneity expressed as a contrast between direct vertical light and light coming from the surroundings allows for a better assessment of the understory light environment and thus of the effect of its variation on species performance. Using repeated measures, we evaluated the effect of vertical light, contrast, and distance to the gap center on the performance of transplanted seedlings of Alnus acuminata, Cornus excelsa, Liquidambar styraciflua, Quercus laurina and Persea americana. Highlands of Chiapas between 999 and 2005 in eight plots of pine-oak forest, each one with a small gap in the middle. Illumination was evaluated with hemispherical photographs at the beginning and the end of the study. We measured stem slenderness and survival after one, two, four, and six years following transplantation. Distance had an effect on survival of Alnus and Liquidambar. Vertical light only had an effect on Liquidambar slenderness. Contrast explained slenderness of Liquidambar, Cornus and Quercus, and survival of Liquidambar, Quercus and Persea conditional on plant age. Initial light contrast predicted the final condition well, which vertical light did not. Contrast between two gradients of the same resource produced a remarkable improvement in the predictive power of light over the performance of the studied species describing the small variations of light in forest understory


5.
- Artículo con arbitraje
Spatial heterogeneity of light and tree sapling responses in the understory of disturbed montane forests
Méndez Dewar, Guadalupe ; González Espinosa, Mario (coaut.) (1950-) ; Equihua, Miguel (coaut.) ;
Contenido en: iForest – Biogeosciences and Forestry Vol. 8, no. 4 (2015), p. 448-455 ISSN: 1971-7458
PDF
Resumen en: Inglés |
Resumen en inglés

Attributes and frequency of forest gaps are usually described in reference to a one-dimensional gradient of light, which may relate to their disturbance dynamics. Similarly, species are customarily classified by their light response. We propose that a bi-dimensional light framework facilitates the understanding and comparison of forest systems and the understanding of plant responses to the complex light environment. This light plane is based on two spatially related components: 1) light received directly on a particular point (Focal); and 2) a statistical summary of the immediate environment representing the light conditions surrounding that point (Context). The contrast between these two values is null when Focal = Context and positive when Focal > Context or otherwise negative. Light was assessed using hemispherical photographs using a spatial arrangement of pictures spaced ~3 metres (m) in-between. Eight forest plots were surveyed, each with a central gap of different size. Sapling performance of Alnus acuminata, Cornus excelsa, Liquidambar styraciflua, Persea americana and Quercus laurina was also assessed within these plots. Measurements of stem height, basal diameter, and slenderness allometry were taken over a period of more than two years. We found in the light plane that plots were distributed in a pattern congruent with their estimated degree of disturbance (gap size), which spanned wide areas in the plane. Liquidambar styraciflua. and Quercus laurina were found to be sensitive to Focal light, irrespective of Context light. All species responded to Focal light under negative Contrast. Cornus and Persea grew taller and more slender as Focal light increased, particularly under null contrast. There is evidence suggesting that plant growth is dependent on the contrast measured. Thus, it would be relevant to devise a functional classification of tree species that considers their response to both direct light.