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59 resultados encontrados para: AUTOR: Golicher, Duncan John
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Resumen en: Inglés |
Resumen en inglés

Quantifying patterns of deforestation and linking these patterns to potentially influencing variables is a key component of modelling and projecting land use change. Statistical methods based on null hypothesis testing are only partially successful for interpreting deforestation in the context of the processes that have led to their formation. Simplifications of cause-consequence relationships that are difficult to support empirically may influence environment and development policies because they suggest simple solutions to complex problems. Deforestation is a complex process driven by multiple proximate and underlying factors and a range of scales. In this study we use a multivariate statistical analysis to provide contextual explanation for deforestation in the Usumacinta River Basin based on partial pattern matching. Our approach avoided testing trivial null hypotheses of lack of association and investigated the strength and form of the response to drivers. As not all factors involved in deforestation are easily mapped as GIS layers, analytical challenges arise due to lack of a one to one correspondence between mappable attributes and drivers. We avoided testing simple statistical hypotheses such as the detectability of a significant linear relationship between deforestation and proximity to roads or water.

We developed a series of informative generalised additive models based on combinations of layers that corresponded to hypotheses regarding processes. The importance of the variables representing accessibility was emphasised by the analysis. We provide evidence that land tenure is a critical factor in shaping the decision to deforest and that direct beam insolation has an effect associated with fire frequency and intensity. The effect of winter insolation was found to have many applied implications for land management. The methodology was useful for interpreting the relative importance of sets of variables representing drivers of deforestation. It was an informative approach, thus allowing the construction of a comprehensive understanding of its causes.


2.
- Capítulo de libro con arbitraje
Evaluación de servicios ambientales hidrológicos en subcuencas del Área Natural Protegida La Frailescana
Escamilla Rivera, Verenice Isabel ; Cortina Villar, Héctor Sergio (coaut.) (1960-) ; Golicher, Duncan John (coaut.) ; Vaca Genuit, Raúl Abel (coaut.) ; Arellano Monterrosas, José Luis Leobardo (coaut.) ;
Contenido en: Suelos de Chiapas: manejo, conservación y restauración Tuxtla, Gutiérrez, México: Universidad Autónoma de Chiapas, 2017 p. 135-157 ISBN:978-607-8459-59-9
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3.
- Artículo con arbitraje
Integración del balance hídrico en la modelación de la distribución de especies de árboles mexicanos
Vaca Genuit, Raúl Abel ; Golicher, Duncan John (coaut.) ;
Contenido en: Botanical Sciences Vol. 94, no. 1 (2016), p. 1-18 ISSN: 2007-4298
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Resumen en: Español | Inglés |
Resumen en español

El modelado de la distribución de especies se basa típicamente en modelos estáticos que integran variables puramente climáticas. Una alternativa es utilizar modelos mecanísticos o semi-mecanísticos que incorporan variables que afectan la respuesta fisiológica de los organismos. En este trabajo demostramos la importancia de complementar el uso de estos dos tipos de modelos para predecir la distribución de especies de árboles mexicanos. Se seleccionaron 258 especies asociadas a cinco diferentes eco- sistemas, que varían en su grado de exposición a los períodos de sequía y se ajustaron modelos aditivos generalizados (GAM). Se mapeó la dinámica anual de humedad del suelo (DHanual) a lo largo de Mesoamérica, y se comparó la habilidad predictiva de este proceso en contraste con modelos ajustados con precipitación anual (Panual). El efecto de la temperatura promedio y intervalo anual de temperatura se incluyó en ambos modelos. DHanual mostró una capacidad significativamente mayor que Panual para predecir la distribución de especies que presentan una respuesta general al estrés hídrico caracterizada por el ahorro y la tolerancia. Se observó un incremento promedio en el AUC al reemplazar Panual por DHanual para los grupos de especies de matorral xerófilo (0.15); de bosque tropical caducifolio (0.09) y de bosque tropical húmedo (0.07). DHanual no contribuyó a mejorar las predicciones para especies de áreas montañosas. El balance hídrico del suelo calculado a escala regional es un predictor valioso para entender diferencias en la distribución de especies de bosques tropicales cálidos de secos a húmedos, donde la temperatura se mantiene comparativamente más constante. Incorporar elementos espaciales, específicamente elevación, podría contribuir a definir mejor la distribución de especies de áreas montañosas.

DHanual introduce una importante fuente de incertidumbre respecto a la información climática debido a la dificultad de integrar parámetros del suelo y la variabilidad geomorfológica que ocurre a escalas locales.

Resumen en inglés

Species distribution models are typically based on relationships between species occurrence and simple climatic variables. An alternative strategy is to use mechanistic or semi-mechanistic models that incorporate variables that are known to have important effects on physiological responses of the organisms. We compared models built using simple climatic variables with models incorporating calculations of monthly soil water balance when predicting the distribution of 258 Mexican tree species associated with five different ecosystems. The species chosen varied in their degree of exposure to periods of drought. Water balance was calculated using a bucket model that integrated the effects of evapotranspiration and rainfall over a year. Models incorporating calculated soil water balance were contrasted with models that used net annual rainfall as a measure of variability in water availability. The effects of mean annual temperature and temperature range were included in both sets of models. More detailed water balance models showed a significantly improved ability to predict the distribution of some, but not all, species. The observed increase in mean AUC when replacing Panual by DHanual was higher for the group of species of xeric scrub (0.15), intermediate for the group of species of deciduous tropical forests (0.09), and significant, but comparatively low for the group of species of tropical moist forests (0.07). Calculated water balance did not improve predictions for species found in montane forests. We conclude that including detailed calculations of soil water balance can improve the species distribution models in areas of both moist and dry warm tropical forests, where temperature remains comparatively constant.

However including variability in soil water balance is less important when species distributions are limited by the effect of elevation on temperature. Model predictions could be further refined through the incorporation of soil parameters and geomorphological variability at a local scales.


4.
- Artículo con arbitraje
Spatial variation of trace metals within intertidal beds of native mussels (Mytilus edulis) and non-native Pacific oysters (Crassostrea gigas): implications for the food web?
Bray, D. J. ; Green, I. (coaut.) ; Golicher, Duncan John (coaut.) ; Herbert, R. J. H. (coaut.) ;
Contenido en: Hydrobiologia Vol. 757, no. 1 (September 2015), p. 235-249 ISSN: 1573-5117
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Resumen en: Inglés |
Resumen en inglés

Pollution is of increasing concern within coastal regions and the prevalence of invasive species is also rising. Yet the impact of invasive species on the distribution and potential trophic transfer of metals has rarely been examined. Within European intertidal areas, the non-native Pacific oyster (Crassostrea gigas) is becoming established, forming reefs and displacing beds of the native blue mussel (Mytilus edulis). The main hypothesis tested is that the spatial pattern of metal accumulation within intertidal habitats will change should the abundance and distribution of C. gigas continue to increase. A comparative analysis of trace metal content (cadmium, lead, copper and zinc) in both species was carried out at four shores in south-east England. Metal concentrations in bivalve and sediment samples were determined after acid digestion by inductively coupled plasma-optical emission spectrometry. Although results showed variation in the quantities of zinc, copper and lead (mg m-²) in the two bivalve species, differences in shell thickness are also likely to influence the feeding behaviour of predators and intake of metals. The availability and potential for trophic transfer of metals within the coastal food web, should Pacific oysters transform intertidal habitats, is discussed.


5.
- Artículo con arbitraje
Mapping the diversity of maize races in Mexico
Perales Rivera, Hugo Rafael ; Golicher, Duncan John (coaut.) ;
Contenido en: PLoS ONE Vol. 9, no. 12, e114657 (December 2014), p. 1-20 ISSN: 1932-6203
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Resumen en: Inglés |
Resumen en inglés

Traditional landraces of maize are cultivated throughout more than one-half of Mexico’s cropland. Efforts to organize in situ conservation of this important genetic resource have been limited by the lack of knowledge of regional diversity patterns. We used recent and historic collections of maize classified for race type to determine biogeographic regions and centers of landrace diversity. We also analyzed how diversity has changed over the last sixty years. Based on racial composition of maize we found that Mexico can be divided into 11 biogeographic regions. Six of these biogeographic regions are in the center and west of the country and contain more than 90% of the reported samples for 38 of the 47 races studied; these six regions are also the most diverse. We found no evidence of rapid overall decline in landrace diversity for this period. However, several races are now less frequently reported and two regions seem to support lower diversity than in previous collection periods. Our results are consistent with a previous hypothesis for diversification centers and for migration routes of original maize populations merging in western central Mexico. We provide maps of regional diversity patterns and landrace based biogeographic regions that may guide efforts to conserve maize genetic resources.


6.
- Capítulo de libro con arbitraje
Restauración ecológica a la chiapaneca
Ferguson, Bruce G. (autor) (1967-) ; Golicher, Duncan John (coaut.) ;
Contenido en: La biodiversidad en Chiapas: estudio de estado / coordinación, edición y seguimiento general: Andrea Cruz Angón, Erika Daniela Melgarejo, Fernando Camacho Rico, Karla Carolina Nájera Cordero Distrito Federal, México : Comisión Nacional para el Conocimiento y Uso de la Biodiversidad : Gobierno del Estado de Chiapas, 2013 Vol. 1, p. 497-505 ISBN:978-607-7607-99-1
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43666-30 (Disponible)
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43666-10 (Disponible)
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43666-20 (Disponible)
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43666-50 (Disponible)
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7.
Tesis - Doctorado
Deforestación y fragmentación de bosques secos en la Depresión Central de Chiapas, México / Raúl Abel Vaca Genuit
Vaca Genuit, Raúl Abel ; Golicher, Duncan John (tutor) ; Cayuela Delgado, Luis (asesor) ; Newton, Adrian C. (asesor) ; Ramírez Marcial, Neptalí (asesor) (1963-) ;
San Cristóbal de Las Casas, Chiapas, México : El Colegio de la Frontera Sur , 2012
Clasificación: TE/333.751370972 / V3
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ECO040004601 (Disponible)
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ECO030007519 (Disponible)
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ECO010015131 (Disponible)
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ECO020011889 (Disponible)
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ECO050004834 (Disponible)
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Índice

Capítulo 1. Introducción y métodos generales
1.1. Introducción general
1.2. Objetivos
1.3. Objetivos específicos, hipótesis y preguntas
1.4. Organización de la tesis doctoral
1.5. Métodos generales
Capítulo 2. Evidence of incipient forest transition in Southern Mexico
2.1. Resumen en castellano
2.2. Introduction
2.3. Methods
2.4. Results
2.5. Discussion
2.6. Conclusions
2.7. Tables and figures
Capítulo 3. Applying climatically based random forest models to downscale coarse grained potential vegetation maps in tropical México
3.1. Resumen en castellano
3.2. Introduction
3.3. Methods
3.4. Results
3.5. Discussion
3.6. Conclusions
3.7. Tables and figures
Capítulo 4. Impact of human land use on dry forest biodiversity in the Central Depression of Chiapas, Mexico
4.1. Resumen en castellano
4.2. Introduction
4.3. Methods
4.4. Results
4.5. Discussion
4.6. Conclusions
4.7. Tables and figures
Capítulo 5. Drivers of deforestation in the Central Depression of Chiapas: Inference on process from pattern analysis using generalised additive models
5.1. Resumen en castellano
5.2. Introduction
5.3. Methods
5.4. Results
5.5. Discussion
5.6. Conclusions
5.7. Tables and figures
Capítulo 6. Discusión y conclusiones generales


8.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Effects of climate change on the potential species richness of mesoamerican forests
Golicher, Duncan John ; Cayuela Delgado, Luis (coaut.) ; Newton, Adrian C. (coaut.) ;
Contenido en: Biotropica Vol. 44, no. 3 (May 2012), p. 284–293 ISSN: 0006-3606
Bibliotecas: San Cristóbal
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5246-20 (Disponible)
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Nota: En hemeroteca, SIBE-San Cristóbal
Resumen en: Inglés |
Resumen en inglés

The realized species richness of tropical forests cannot yet be reliably mapped at a regional scale due to lack of systematically collected data. An estimate of the potential species richness (PSR), however, can be produced through the use of species distribution modelling. PSR is interpretable as a climatically determined upper limit to observed species richness. We mapped current PSR and future PSR under climate change scenarios for Mesoamerica by combining the spatial distributions of 2000 tree species as predicted by generalized additive models built from herbaria records and climate layers. An explanatory regression tree was used to extract conditional rules describing the relationship between PSR and climate. The results were summarized by country, ecoregion and protected area status in order to investigate current and possible future variability in PSR in the context of regional biodiversity conservation. Length of the dry season was found to be the key determinant of PSR. Protected areas were found to have higher median PSR values than unprotected areas in most of the countries within the study area. Areas with exceptionally high PSR, however, remain unprotected throughout the region. Neither changes in realized species richness nor extinctions will necessarily follow changes in modelled PSR under climate change. However model output suggests that an increase in temperature of around 3°C, combined with a 20 percent decrease in rainfall could lead to a widespread reduction of around 15 percent of current PSR, with values of up to 40 percent in some moist lower montane tropical forests. The modelled PSR of dry forest ecoregions was found to be relatively stable. Some cooler upper montane forests in northern Mesoamerica, where few species of tropical origin are currently found, may gain PSR if species are free to migrate.


9.
Artículo
Evidence of incipient forest transition in southern Mexico
Vaca Genuit, Raúl Abel (coaut.) ; Golicher, Duncan John (coaut.) ; Cayuela Delgado, Luis (coaut.) ; Hewson, Jenny (coaut.) ; Steinmann, Víctor W. (coaut.) ;
Contenido en: PLoS ONE Vol. 7, no. 8, e42309 (August 2012), p. 1-15 ISSN: 1932-6203
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Resumen en: Inglés |
Resumen en inglés

Case studies of land use change have suggested that deforestation across Southern Mexico is accelerating. However, forest transition theory predicts that trajectories of change can be modified by economic factors, leading to spatial and temporal heterogeneity in rates of change that may take the form of the Environmental Kuznets Curve (EKC). This study aimed to assess the evidence regarding potential forest transition in Southern Mexico by classifying regional forest cover change using Landsat imagery from 1990 through to 2006. Patterns of forest cover change were found to be complex and non-linear. When rates of forest loss were averaged over 342 municipalities using mixed-effects modelling the results showed a significant (p<0.001) overall reduction of the mean rate of forest loss from 0.85% per year in the 1990–2000 period to 0.67% in the 2000–2006 period. The overall regional annual rate of deforestation has fallen from 0.33% to 0.28% from the 1990s to 2000s. A high proportion of the spatial variability in forest cover change cannot be explained statistically. However analysis using spline based general additive models detected underlying relationships between forest cover and income or population density of a form consistent with the EKC.

The incipient forest transition has not, as yet, resulted in widespread reforestation. Forest recovery remains below 0.20% per year. Reforestation is mostly the result of passive processes associated with reductions in the intensity of land use. Deforestation continues to occur at high rates in some focal areas. A transition could be accelerated if there were a broader recognition among policy makers that the regional rate of forest loss has now begun to fall. The changing trajectory provides an opportunity to actively restore forest cover through stimulating afforestation and stimulating more sustainable land use practices. The results have clear implications for policy aimed at carbon sequestration through reducing deforestation and enhancing forest growth.


10.
Capítulo de libro
*Solicítelo con su bibliotecario/a
Montañas del Norte y Altos de Chiapas
Challenger, Antony ; Golicher, Duncan John (coaut.) ; González Espinosa, Mario (coaut.) (1950-) ; March Mifsut, Ignacio José (coaut.) ; Ramírez Marcial, Neptalí (coaut.) (1963-) ; Vidal Rodríguez, Rosa María (coaut.) ;
Contenido en: El bosque mesófilo de montaña en México: amenazas y oportunidades para su conservación y manejo sostenible México : Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, 2012 p. 133-151 ISBN:9786077607359
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