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11 resultados encontrados para: AUTOR: Rogan, John
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Resumen en: Inglés |
Resumen en inglés

Land system science axiomatically addresses social–environmental systems by integrating the dynamics of land uses (social) and land covers (environment), invariably including the use of remote sensing data and often, spatially explicit models of land change. This kind of research is illustrated through the Southern Yucatán Peninsular Region project (1997–2008) aimed at understanding, predicting, and projecting spatially explicit land change in a region with juxtaposed land uses-agriculture and a biosphere reserve. The successes of the project, its contributions to contemporary land system science, and the organizational mechanisms that fostered the research are identified as well as various corrections, which if applied, may have refined and extended the project's goals. Overall, the project demonstrates the kind of integrated research required to advance understanding of a social-environment system and the team-based methods used in the process.


Resumen en: Inglés |
Resumen en inglés

Land system science axiomatically addresses social– environmental systems by integrating the dynamics of land uses (social) and land covers (environment), invariably including the use of remote sensing data and often, spatially explicit models of land change. This kind of research is illustrated through the Southern Yucata´ n Peninsular Region project (1997–2008) aimed at understanding, predicting, and projecting spatially explicit land change in a region with juxtaposed land uses-agriculture and a biosphere reserve. The successes of the project, its contributions to contemporary land system science, and the organizational mechanisms that fostered the research are identified as well as various corrections, which if applied, may have refined and extended the project’s goals. Overall, the project demonstrates the kind of integrated research required to advance understanding of a social-environment system and the team-based methods used in the process.


3.
Artículo
Using food flow data to assess sustainability: land use displacement and regional decoupling in Quintana Roo, Mexico
Millones, Marco ; Parmentier, Benoit (coaut.) ; Rogan, John (coaut.) ; Schmook, Birgit Inge (coaut.) ;
Contenido en: Sustainability ISSN: 2071-1050
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Resumen en: Inglés |
Resumen en inglés

Food flow data provide unique insights into the debates surrounding the sustainability of land based production and consumption at multiple scales. Trade flows disguise the spatial correspondence of production and consumption and make their connection to land difficult. Two key components of this spatial disjuncture are land use displacement and economic regional decoupling. By displacing the environmental impact associated with food production from one region to another, environmental trajectories can falsely appear to be sustainable at a particular site or scale. When regional coupling is strong, peripheral areas where land based production occurs are strongly linked and proximate to consumption centers, and the environmental impact of production activities is visible. When food flows occur over longer distances, regional coupling weakens, and environmental impact is frequently overlooked. In this study, we present an analysis of a locally collected food flow dataset containing agricultural and livestock products transported to and from counties in Quintana Roo (QRoo). QRoo is an extensively forested border state in southeast Mexico, which was fully colonized by the state and non-native settlers only in the last century and now is home to some of the major tourist destinations. To approximate land displacement and regional decoupling, we decompose flows to and from QRoo by (1) direction; (2) product types and; (3) scale. Results indicate that QRoo is predominantly a consumer state: incoming flows outnumber outgoing flows by a factor of six, while exports are few, specialized, and with varied geographic reach (Yucatan, south and central Mexico, USA).

Imports come predominantly from central Mexico. Local production in QRoo accounts for a small portion of its total consumption. In combining both subsets of agricultural and livestock products, we found that in most years, land consumption requirements were above 100% of the available land not under conservation in QRoo, suggesting unsustainable rates of land consumption in a ´business as usual´ scenario. We found evidence of economic regional decoupling at the state level.


4.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

This study explores the temporal and spatial variability and change in rainfall across southeastern Mexico and the mechanisms by which smallholder farmers adapt to this variability, especially droughts. Members of 150 households in 10 communities were interviewed to investigate adaptation strategies among swidden maize smallholders, linked to their perceptions of climate changes. Precipitation data from seven weather stations were analyzed for the 1973–2012 period. Precipitation anomalies were estimated to evaluate the annual and seasonal stability, deficit, or surplus; and linear regressions were used to evaluate trends. Then, these anomalies were linked to variation in reported agricultural practices. Weather station data show a considerable decline in precipitation in most of the study area, coupled with increased drought frequency and an increase in negative anomalies in recent years. Surveys revealed several mechanisms of adaptation, including adjustment of the agricultural calendar (e.g. delaying planting, combined with planting a greater number of varieties of maize), water storage, and livelihood diversification both within and outside of agriculture. These adaptive mechanisms are responsive to demonstrated climatic change over the past 40 years, though globalization affects Mexico's agrarian economy, and farmers likely respond to a combination of economic and climatic factors. Understanding how resource- and climate-dependent swidden farmers respond to co-occurring climatic and economic changes is essential for effective adaptation policy design.


5.
- Capítulo de libro con arbitraje
*Solicítelo con su bibliotecario/a
Precipitation variability and adaptation strategies in the southern Yucatán Peninsula, Mexico: integrating local knowledge with quantitative analysis
Márdero Jiménez, Silvia Sofía ; Schmook, Birgit Inge (coaut.) ; Christman, Zachary John (coaut.) ; Nickl Alcocer, Elsa Cristina (coaut.) ; Schneider, Laura (coaut.) ; Rogan, John (coaut.) ; Lawrence, Deborah (coaut.) ;
Contenido en: International Perspectives on Climate Change Switzerland, German : Springer International Publishing, 2014 p. 189-201 ISBN:978-331-9044-88-0
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Climatic variability, including droughts, has long affected the Mayan Lowlands. Therefore, farmers have developed coping strategies to mitigate these impacts. In the past, however, records of these effects and responses were largely anecdotal. In modern times, the perceptions of farmers, especially those practicing rain-fed agriculture, combined with the increased availability of accurate historical climatic records and forecasts, can provide useful information regarding periods of decreased precipitation and strategies employed to resist and respond to drought effects. As part of the multidisciplinary and inter-institutional project, New Knowledge about Ecosystem Level Response to Increased Frequency of Large-Scale Natural Disturbance Driven by Climate Change, this chapter outlines the spatial and temporal variability of precipitation across the Southern Yucatán Peninsula, Mexico, and examines Mayan farmers’ adaptations to droughts and other climate perturbations. The authors analyzed precipitation trends and anomalies from 1953 to 2007, using linear regressions and the quintile method to classify meteorological droughts. Authors also conducted 150 household interviews across 10 communities to investigate Mayan farmers’ adaptations to climate perturbations.

Results demonstrate a significant decrease in annual and rainy season precipitation across much of the study area, coupled with an increased occurrence of droughts, especially since 1980. Interviewed subsistence maize farmers have adapted to decreasing and irregular precipitation by adjusting agricultural calendars, planting more maize varieties, increasing water storage, and diversifying their practices both within the agricultural system and beyond it. Through this research, the authors demonstrate the importance of incorporating farmers’ local and traditional knowledge into prevention and mitigation policies of governmental and non-governmental institutions in the region.


6.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Damage patterns after Hurricane Dean in the southern Yucatán: has human activity resulted in more resilient forests?
McGroddy, Megan ; Lawrence, Deborah (coaut.) ; Schneider, Laura C. (autora) ; Rogan, John (autor) ; Zager, Irene (autora) ; Schmook, Birgit Inge (autora) ;
Disponible en línea
Contenido en: Forest Ecology and Management Vol. 310, (December 2013), p. 812–820 ISSN: 0378-1127
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

We investigated how patterns of hurricane damage were related to windspeed, stand characteristics, and land use in a region where forest composition and structure have been strongly influenced by human activities. In 2007 Hurricane Dean hit the biological corridor between the two largest biosphere reserves on the Yucatán Peninsula as a category 5 hurricane. Land use in the corridor has altered both landscape and forest stand structure. Compared to the upland protected areas, forests in the study area were significantly shorter and characterized by smaller stems. Nine months after the hurricane we assessed the damage in a set of 91 plots to test the effect of local stand structure on hurricane resistance. For each 5 × 100 m plot, we calculated the proportion of both stems and basal area damaged using 7 classes (no damage, small branch, major branch, stem bent, stem snapped, tree uprooted and tree death). Interviews with land- owners provided recent land use histories for the past 30 years for most study plots. For the two dominant forest types analysis of variance found that canopy height, median dbh and basal area all varied significantly with land use history and forest type. We tested the effect of median stem diameter, canopy height, stem density, basal area and tree species density on damage. Despite the strength of the storm, on average 27% of stems at the stand level showed no signs of damage and only 5% across the study were killed by the hurricane. In step-wise linear regression models, 13–52% of the variation in damage frequency was accounted for by windspeed and stand structure. Canopy height, basal area and median dbh were significant predictors. For moderate to severe damage classes, measures of stand size were generally positively correlated with damage frequency suggesting that stands with higher canopies and/or greater basal area or median dbh suffered the most during this storm event.


7.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

This research examines the spatio-temporal trends in Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modelling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) time series to ascribe land use change and precipitation to observed changes in land cover from 1982 to 2007 in the Mexican Yucatán Peninsula, using seasonal trend analysis (STA). In addition to discrete land cover transitions across the study region, patterns of agricultural intensification, urban expansion and afforestation in protected areas have enacted changes to the seasonal patterns of apparent greenness observed through STA greenness parameters. The results indicate that the seasonal variation in NDVI can be used to distinguish among different land cover transitions, and the primary differences among these transitions were in changes in overall greenness, peak annual greenness and the timing of the growing season. Associations between greenness trends and precipitation were weak, indicating a human-dominated system for the 26 years examined. Changes in the states of Campeche, Quintana Roo and Yucatán appear to be associated with pasture cultivation, urban expansion-extensive cultivation and urban expansion-intensive cultivation, respectively.


8.
- Artículo con arbitraje
*En hemeroteca, SIBE-Campeche, SIBE-San Cristóbal, SIBE-Villahermosa, SIBE-Tapachula
Sequías en el sur de la Península de Yucatán: análisis de la variabilidad anual y estacional de la precipitación
Márdero Jiménez, Silvia Sofía ; Nickl Alcocer, Elsa Cristina (coaut.) ; Schmook, Birgit Inge (coaut.) ; Schneider, Laura C. (coaut.) ; Rogan, John (coaut.) ; Christman, Zachary John (coaut.) ; Lawrence, Deborah (coaut.) ;
Contenido en: Investigaciones Geográficas No. 78 (2012), p. 19-33 ISSN: 0188-4611
Cerrar
SIBE Campeche
40003-30 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
40003-20 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Tapachula
40003-50 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Villahermosa
40003-40 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-Campeche, SIBE-San Cristóbal, SIBE-Villahermosa, SIBE-Tapachula
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Resumen en: Español | Inglés |
Resumen en español

Este estudio analiza la variabilidad espacial y temporal de la precipitación en el sur de la península de Yucatán, a través de anomalías y tendencias de la precipitación anual y estacional y la ocurrencia de sequías meteorológicas, empleando datos de lluvia de nueve estaciones meteorológicas para el periodo de 1953-2007. Utilizando tendencias de regresión lineal anuales y estacionales se analizó el aumento o la disminución de las precipitaciones durante este periodo. Las anomalías de precipitación permitieron evaluar la estabilidad, el déficit o superávit de precipitación para cada año, y el método quintil permitió la clasificación de la intensidad de las sequías meteorológicas. Los resultados muestran una considerable variabilidad espacial y temporal, con mayores valores de precipitación y anomalías en la costa, que van disminuyendo gradualmente hacia el Centro-Oeste del área en estudio. Durante este periodo hay una disminución de la precipitación anual y de la estación húmeda, en gran parte de la zona la cual alcanza una disminución de 12 mm anuales (estación Chachobben). Estaciones como Zoh Laguna Campeche muestran claramente un aumento en los años de sequía (desde leve hasta extrema) a partir de 1985 principalmente. Este estudio contribuye a un major conocimiento de la variación regional de la precipitación y sus posibles vínculos con el Cambio Climático a escala regional y global.

Resumen en inglés

This study analyzes the spatial and temporal variability of precipitation across the Southern Yucatán Peninsula in Mexico, addressing the anomalies and trends of annual and seasonal precipitation as well as the occurrence of meteorological droughts, using rainfall data from nine weather stations during the period 1953-2007. Linear regression in the annual and seasonal rainfall were used to analyze the increase or decrease in precipitation trends over this period. Precipitation anomalies enabled the evaluation of the stability, deficit, or surplus of precipitation for each year or season, and a quintile method was used to classify the intensity of meteorological droughts. The results exhibit considerable spatial and temporal variability, with higher values of precipitation and precipitation anomalies at the Caribbean coast, which gradually decrease towards the mid-west of the region. Results exhibit a significant decrease in annual and rainy-season precipitation in much of the area cover in this study, by as much as 12 mm less per year (Chachobben station). Other weather stations, such as Zoh Laguna, show an increase in years of drought (ranging from mild to extreme), especially since the early 1980´s. We hope that the results of this study will contribute to a better understanding of regional precipitation variability, with links to broader-scale Climate Change.


9.
- Artículo con arbitraje
High mortality for rare species following hurricane disturbance in the southern Yucatán
Vandecar, Karen L. ; Lawrence, Deborah (coaut.) ; Richards, Dana (coaut.) ; Schneider, Laura (coaut.) ; Rogan, John (coaut.) ; Schmook, Birgit Inge (coaut.) ; Wilbur, Henry (coaut.) ;
Contenido en: Biotropica Vol. 43, no. 6 (November 2011), p. 676–684 ISSN: 0006-3606
Resumen en: Inglés |
Resumen en inglés

Hurricanes are an important part of the natural disturbance regime of the Yucatán Peninsula with the potential to alter forest structure and composition, yet investigations of species-level responses to severe winds are limited in this region. The effect of a category 5 hurricane (Hurricane Dean, 21 August 2007) on dry tropical forests across the southern Yucatán was examined with respect to tree damage, mortality, and sprouting. Damage was assessed 9–11 mo following the hurricane in 92 (500 m2) plots stratified by wind speed and normalized difference vegetation index (NDVI) change classes over a 25,000 km2 study area. We investigated the relative importance of biotic (i.e., species, size, and wood density) and abiotic (i.e., wind speed) factors to better explain patterns of damage. Overall mortality was low (3.9%), however, mortality of less common species (8.5%) was elevated more than fourfold above that of 28 common species (1.8%), indicating immediate selective consequences for community composition. Species varied in the degree and type of damage experienced, with susceptibility increasing with tree diameter and height. Wood density influenced damage patterns only in areas where a critical threshold in storm intensity was exceeded (wind speeds ≥210 km/h). Although overall, damage severity increased with wind speed, common coastal species were more resistant to damage than species distributed farther inland. Our findings suggest that selective pressure exerted by frequent hurricane disturbance has, and will, continue to impact the floristic composition of forests on the Yucatán Peninsula, favoring certain wind-resistant species.


10.
Artículo
Hurricane disturbance mapping using MODIS EVI data in the southeastern Yucatán, Mexico
Schneider, Laura C. ; Rogan, John ; Christman, Zachary John (coaut.) ; Millones, Marco (coaut.) ; Lawrence, Deborah (coaut.) ; Schmook, Birgit Inge (coaut.) ;
Contenido en: Remote Sensing Letters Vol. 2, no. 3 (September 2011), p. 259-267 ISSN: 2150-704X
Resumen en: Inglés |
Resumen en inglés

This letter evaluated the use of Moderate Resolution Imaging Spectroradiometer (MODIS) 250 mEnhanced Vegetation Index (EVI) standard product data (MOD/ MYD13Q1 C5) to map the damage caused by Hurricane Dean (August 2007) to the forests in the Yucata´n Peninsula of Mexico using a two-step vetting procedure. Sequences of MODIS EVI 16-day composite products captured before and after the hurricane were compared against 93 field damage plots to select an appropriate set of pre- and post-damage data. Aqua pairwise combinations produced the highest damage detection overall accuracy compared with Terra (82.4% vs. 73.8%, respectively) because of advantageous timing of the Aqua EVI compositing, relative to the hurricane event. The most accurate EVI damage map (91.4% overall) revealed highest damage detection in Saffir–Simpson hurricane wind scale zone 5 (i.e. wind speed .248 km h-1, i.e. 95%), followed by 93% in zone 4 (210–249 km h-1) and 87% in zone 3 (178–209 km h-1). Results indicate that MODIS EVI products provide timely and accurate maps of hurricane damage in subtropical forests.