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5 resultados encontrados para: AUTOR: Ellis, Edward Alan
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1.
Artículo
Mapping disturbance from selective logging in tropical forests of the Yucatan Peninsula, Mexico
Hernández Gómez, Irving Uriel (autor) ; Vázquez Luna, Dinora (autora) ; Cerdán Cabrera, Carlos Roberto (autor) ; Navarro Martínez, María Angélica (autora) ; Ellis, Edward Alan (autor) ;
Disponible en línea
Contenido en: Tropical and Subtropical Agroecosystems Volumen 23, número 1 (2020), páginas 143-152 ISSN: 1870-0462
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Resumen en: Español | Inglés |
Resumen en español

El mapeo de los impactos de la tala selectiva en la Península de Yucatán es importante para lograr la reducción de las emisiones de carbono y los objetivos de conservación de la biodiversidad. Objetivo. Evaluar la efectividad de la aplicación de técnicas de teledetección mediante el uso de imágenes LANDSAT 8 OLI para detectar la perturbación del bosque tropical a partir de la extracción de madera en cuatro bosques con manejo comunitario (ejidos). Además, evaluamos las diferencias entre ellos en términos de implementación de manejo forestal mejorado (IFM) y prácticas de aprovechamiento de impacto reducido (RIL). Metodología. Se calcularon los índices de vegetación y se realizó la clasificación de la cubierta forestal para hacer un mapa de las zonas taladas y no taladas y las perturbaciones específicas del aprovechamiento (por ejemplo, claros por la tala de árboles, carriles de arrastre, caminos forestales y áreas de acopio de madera) en las áreas de corta anual de 2014. Las evaluaciones de precisión se realizaron en función de los puntos de validación colectados en el campo después del aprovechamiento. Resultados. Encontramos que el 75% de las clasificaciones binarias (áreas impactadas y no impactadas) tenían precisiones globales medias superiores al 60%, lo que representa una precisión aceptable (40 a 70%), aunque el mapeo de las perturbaciones específicas de la cosecha tuvo poca precisión (<40%). Los índices de vegetación que obtuvieron los mejores resultados fueron el índice de vegetación de diferencia normalizada (NDVI), Tasseled Cap Greenness y Tasseled Cap Wetness. Los ejidos que aplicaron IFM y RIL impactaron un porcentaje menor de sus áreas de corta y menos área de bosque por metro cúbico de madera extraída, a pesar de intensidades de tala similares o mayores que los ejidos sin prácticas mejoradas.

Implicaciones. El monitoreo del impacto por la tala selectiva es importante para mejorar el manejo forestal y la certificación de sostenibilidad. Conclusiones. El mapeo y el monitoreo de los impactos de la tala selectiva por gestores y técnicos forestales se puede realizar de manera costo-efectiva utilizando imágenes LANDSAT 8, aunque la precisión se puede mejorar con imágenes de alta resolución.

Resumen en inglés

Background. Mapping selective logging impacts on the Yucatan Peninsula is important to pursuing carbon emissions reduction and biodiversity conservation goals. Objective. To evaluate the effectiveness of applying remote sensing techniques using LANDSAT 8 OLI imagery to detect tropical forest disturbance from timber harvesting in four communally managed forests (ejidos). We further assess differences among them in terms of implementing improved forest management (IFM) and reduced impact logging (RIL). Methodology. Vegetation indices were calculated, and forest cover classification was performed to map logged and unlogged forest and specific harvest disturbances (e.g. felling gaps, skid trails, logging roads and log landings) in annual cutting areas of 2014. Accuracy assessments were conducted based on validation points collected in the field after logging. Results. We found that 75% of the binary classifications (logged and unlogged forest) had mean overall accuracies greater than 60%, representing a fair (40 to 70%) accuracy, although mapping of specific harvesting disturbances had poor accuracy (<40%). Vegetation indices that performed the best were normalized vegetation index (NDVI), Tasseled Cap Greenness and Tasseled Cap Wetness. Ejidos that applied IFM and RIL impacted a smaller percentage of their cutting areas and less area of forest per cubic meter of timber extracted, despite similar or higher logging intensities than ejidos without improved practices. Implication. Monitoring selective logging disturbance is important to improved forest management and certification of sustainability. Conclusion. Mapping and monitoring impacts from selective logging by forest managers and technicians can be performed in a cost-efficient manner using LANDSAT 8 images, although accuracy could be improved with higher resolution imagery.


2.
Artículo
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Resumen en: Inglés |
Resumen en inglés

Detecting and monitoring forest disturbance from selective logging is necessary to develop effective strategies and polices that conserve tropical forests and mitigate climate change. We assessed the potential of using the remote sensing tool, CLASlite forest monitoring system, to detect disturbance from timber harvesting in four community forests (ejidos) of the Selva Maya on the Yucatan Peninsula, Mexico. Selective logging impacts (e.g. felling gaps, skid trails, logging roads and log landings) were mapped using GPS in the 2014 annual cutting areas (ACAs) of each ejido. We processed and analyzed two pre-harvest Landsat images (2001 and 2013) and one post-harvest image (November 2014) with the CLASlite system, producing maps of degraded, deforested and unlogged areas in each ACA. Based on reference points of disturbed (felling and skidding), deforested (log landings and roads) and unlogged areas in each ACA, we applied accuracy assessments which showed very low overall accuracies (<19.1%). Selective logging impacts, mainly from log landings and new logging road construction, were detected in only one ejido which had the highest logging intensity (7 m³ ha–¹).


3.
- Artículo con arbitraje
*Solicítelo con su bibliotecario/a
Distribution and Abundance of Big-Leaf Mahogany (Swietenia macrophylla) on the Yucatan Peninsula, Mexico
Navarro Martínez, María Angélica (autora) ; Ellis, Edward Alan (autor) ; Hernández Gómez, Irving Uriel (autor) ; Romero Montero, José Arturo (autor) ; Sánchez Sánchez, Odilón Manuel (autor) ;
Contenido en: Tropical Conservation Science Vol. 11 (2018), p. 1–17 ISSN: 1940-0829
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Big-leaf mahogany (Swietenia macrophylla King) is an economically important timber species in the Neotropics. For over three centuries, it has been selectively extracted from tropical forests, threatening its populations. We investigate the actual and potential distribution of big-leaf mahogany and assess its abundance on the Yucatan Peninsula based on the National Forest and Soils Inventory database. Furthermore, we evaluate environmental factors associated with its distribution, abundance, and tree size. The actual and potential distribution models show the presence of mahogany in a wide geographic area covering the southern and eastern portions of the Yucatan Peninsula. Abundance of mahogany in the landscape varies and in general is low. The spatial potential distribution model was best explained by the environmental variables of vegetation cover (medium- and high-stature semievergreen tropical forest) and elevation (upland areas). Results also indicate that mahogany remains relatively abundant and contain larger size classes in localities where the species has been harvested and managed for decades under community forest management. Furthermore, statistical analyses show greater tree density of mahogany mostly associated with low-stature semievergreen tropical forest having deep soils (gleysols and vertisols), while larger tree size (diameter at breast height) was associated with medium-stature semievergreen tropical forests in upland areas with moderately deep or shallow soils (mostly rendzinas or leptosols). Despite deforestation, land-use change and forestry activities on the Yucatan Peninsula, particularly in the past 20 years, the distribution and abundance of mahogany do not appear to be as drastically reduced as described in other neotropical regions.


4.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Land use/land cover change dynamics and drivers in a low-grade marginal coffee growing region of Veracruz, Mexico
Ellis, Edward Alan ; Baerenklau, Kenneth A. (coaut.) ; Marcos Martínez, Raymundo (coaut.) ; Chávez, Edgar (coaut.) ;
Contenido en: Agroforestry Systems Vol. 80, no. 1 (September 2010), p. 61-84 ISSN: 0167-4366
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
49837-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
Resumen en: Inglés |
Resumen en inglés

In the state of Veracruz, Mexico, lowland and marginal coffee growing regions have been particularly vulnerable since the 1989 coffee crisis. Government programs have promoted production diversification as a strategy to improve local incomes and conserve environmentally beneficial shade-tree coffee agroforests. We present results on land use/land cover dynamics in the municipality of Zozocolco de Hidalgo from 1973 to 2006. The municipality is recognized for its indigenous population and poverty, and currently, diversification efforts are being implemented. Our study combines remote sensing and GIS analyses, binary logistic regression and econometric modeling, as well as socioeconomic surveys to evaluate land use/land cover change (LULCC) dynamics and explore potential environmental and socioeconomic drivers. Results show that tree cover and coffee agroforests had largely been conserved during the first decade after the coffee crisis. But, recent trends indicate loss of tree cover in coffee agroforests and their conversion mostly to pasture. Land use/land cover drivers are largely explained by spatially explicit environmental variables such as slope and elevation. Relevant socioeconomic variables such as distance to markets and land use profitability were not significantly related to land use changes in Zozocolco. Surveys revealed that many households had converted coffee agroforests to pasture or agriculture in the past decade and others intended on renting or selling their agroforest plots, mostly for conversion to pasture. Diversification programs may not be sufficient to stem deforestation in lowland and marginal coffee growing regions. Moreover, information about locally varying socioeconomic and cultural contexts needs to be strongly considered in order to formulate effective strategies.


5.
Artículo
*En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula
La conformación del paisaje y el aprovechamiento de los recursos naturales por las comunidades mayas de La Montaña, Hopelchén, Campeche
Porter Bolland, Luciana ; Sánchez González, María Consuelo (coaut.) ; Ellis, Edward Alan (coaut.) ;
Contenido en: Investigaciones Geográficas No. 66 (agosto 2008), p. 65-104 ISSN: 0188-4611
Bibliotecas: Chetumal , San Cristóbal , Tapachula
Cerrar
SIBE Chetumal
46976-20 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE San Cristóbal
46976-10 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Tapachula
46976-30 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula
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Resumen en: Español | Inglés |
Resumen en español

Se presenta un análisis de la historia de uso del suelo en la región de La Montaña, municipio de Hopelchén, Campeche, realizado a partir de una recopilación de la documentación histórica existente, complementado con información proporcionada por habitantes del lugar. De igual forma, se presenta una caracterización de la población actual y sus sistemas productivos, utilizando información obtenida mediante encuestas, entrevistas y talleres. La Montaña comprende ocho ejidos cuya población maya-hablante tiene una historia de uso de los recursos naturales de más de tres mil años. La estructura y composición del paisaje en esta zona han sido moldeadas por diferentes factores tanto naturales como sociales, estos últimos guiados por intereses tanto internos como externos. Los cambios poblacionales y los movimientos migratorios internos han sido una de las constantes de la región, con una población maya de 14 400 habitantes en 1860, que disminuyó a menos de 5 000 en el 2005. A pesar de la baja densidad poblacional, las actividades productivas recientes están adquiriendo un carácter más agropecuario, modificando la estructura y composición del paisaje. Como propuesta para mejorar la calidad de vida de los pobladores de la región sin comprometer la riqueza natural de la zona, se requiere una inversión tanto en capital social como en términos económicos, para poder impulsar prácticas de manejo que sean ecológica y socialmente sostenibles. El reconocimiento de este territorio maya debe ser consensual, donde los pobladores locales participen de forma activa en el proceso de desarrollo de la región y no como mano de obra barata en la explotación no sustentable de la selva.

Resumen en inglés

This manuscript provides a landscape history analysis for the region of La Montaña, located at the municipality of Hopelchen of the state Campeche, Mexico. The information was obtained through a literature review on historic sources and complemented with information provided by the local inhabitants. Also, a characterization is provided regarding the population’s current situation, including their productive systems. This region is comprised of eight ejidos whose Mayan population has a history of land use of at least 3 000 years. The structure and composition of the landscape has been molded by natural and social factors. Changes in population densities and internal migration have occurred constantly. Current history indicates that the fluctuating population has varied from 14 400 inhabitants in 1860 to less than 5 000 in 2005. In spite of today’s low population densities, recent productive activities are turning to be more agricultural oriented, modifying the structure and composition at the landscape level. Investment in the region is needed both, in economic terms and for strengthening social capital in order to promote productive activities that are ecological and socially sound, improving the welfare of local inhabitants without compromising its natural resources. The acceptance of this Mayan territory should be consensual, as one in which local inhabitants have the right to actively participate in development processes and not merely as cheap manual labor.