Términos relacionados

6 resultados encontrados para: AUTOR: Dietsch, Thomas V.
  • «
  • 1 de 1
  • »
1.
Artículo
*En hemeroteca, SIBE-San Cristóbal
A relationship between avian foraging behavior and infestation by trombiculid larvae (Acari) in Chiapas, Mexico
Dietsch, Thomas V. ;
Contenido en: Biotropica Vol. 40, no. 2 (March 2008), p. 196-202 ISSN: 0006-3606
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
45278-10 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
Resumen en: Español | Inglés |
Resumen en español

Las aves enfrentan riesgos que varían según su selección y utilización del hábitat. Desafortunadamente, las correlaciones de comportamiento y hábitat del parasitismo en aves no están bien documentados. Este estudio combina datos de un estudio de comportamiento de forrajeo con resultados de un estudio de anillamiento para probar si el comportamiento y el hábitat afectan la infestación del ectoparásito de larvas del ácaro Trombiculidae en la comunidad del aves encontrada en dos agroecosistemas del café differente en Chiapas, México. Los individuos de especies de aves con prevalencia regular (i.e., infestación) forrajearon con más frecuencia en el nivel de vegetación más bajo y tuvieron una menor altura de forraje que aquellas especies con poco o nada de prevalencia, sugiriendo que forrajear cerca del suelo incrementa el riesgo de exposición a las larvas del Trombiculidae. Usando la regresión linear, a través de las especies, el predominio del parásito disminuyó con el aumento de la altura media de forrajeo. La prevalencia de la infestación fueron más bajas en agroecosistemas de café con una mayor intensidad de manejo (i.e., condiciones con menos sombra y mas seco), sugiriendo que las actividades de manejo influyen las tasas de infestación. Por lo tanto, los hábitats tropicales secos pueden representar menor riesgo de ectoparásitos para las aves, aunque la prevalencia estacional fue más alta durante la estación seca del invierno. Aunque no se encontró ninguna interacción directa entre la condición del hospedero y la infestación con las larvas de acaro en las tierras invernales, las aves fueron muestreadas durante la mitad del período de invierno y no en al final cuando la infestación podría afectar a las aves que acumulan grasa para la migración.

Resumen en inglés

Birds face varying risk from parasites as they select and utilize habitat. Unfortunately, behavioral and habitat correlates of parasitism in birds are not well documented. This study combines data from a foraging behavior study with results from a banding study to test whether behavior and habitat affect an ectoparasite infestation by trombiculid mite (chigger) larvae on the bird community found in two different coffee agroecosystems in Chiapas, Mexico. Individuals from bird species with regular prevalence (i.e., infestation) foraged more frequently in lower vegetative layers and had significantly lower foraging height than those from species with little or no prevalence, suggesting that foraging near the ground increases exposure risk to chigger larvae. Using linear regression, across species, parasite prevalence decreased with increasing average foraging height. Lower infestation rates were found in coffee agroecosystems with higher management intensity (i.e., less shade and drier conditions), suggesting that management activities influence infestation rates. Consequently, drier tropical habitats may pose less risk to birds from ectoparasites, though seasonal prevalence was highest during the winter dry season. Although no direct link was found between host condition and infestation by chigger larvae on the wintering grounds, birds were sampled during the middle of the over-wintering period, not the end when infestation could affect birds fattening for migration.


2.
- Capítulo de libro con arbitraje
*Solicítelo con su bibliotecario/a
Shaded coffee and the stability of rainforest margins in northern Latin America
Perfecto, Ivette (autora) ; Armbrecht, Inge (autora) ; Phillpott, Stacy M. (autora) ; Soto Pinto, Lorena (autora) (1958-) ; Dietsch, Thomas V. (autor) ;
Disponible en línea
Contenido en: Stability of tropical rainforest margins: linking ecological, economic and social constraints of land use and conservation Berlin, Heidelberg, Germany : Springer-Verlag Berlin Heidelberg, 2007 páginas 227-263 ISBN:3-540-30289-1 :: 978-3-540-30289-6
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
37685-20 (Disponible)
Disponibles para prestamo: 1
Nota: Solicítelo con su bibliotecario/a
Resumen en: Inglés |
Resumen en inglés

Most native forests in Latin America are highly fragmented. In the mid elevation areas of Northern Latin America, the agricultural matrix is frequently composed of coffee. In this region, coffee has been traditionally cultivated under the diverse canopy of shade trees, representing a high quality matrix that can contribute to the social and ecological stability of the region. This agroforestry system has been proven to be important for biodiversity conservation. Studies over the last fifteen years have shown that shaded coffee plantations maintain a high diversity of vertebrates, invertebrates and plants. These organisms play an important role in the functioning of coffee agroecosystems. Shaded coffee plantations promote a high abundance and diversity of natural enemies that help to regulate herbivores, weeds and diseases. Shaded plantations also harbor a higher diversity of native pollinators which have been shown to contribute to higher coffee yields. Likewise, the diverse shade-tree component contributes to soil fertility and soil conservation and has been shown to contribute significantly to carbon sequestration.

As a matrix, coffee agroforests also contribute to the conservation of biodiversity withinforest fragments by promoting migration among fragments and facilitating a metapopulation structure. Three “sustainable” coffee certification programs have been developed to help farmers cope with the vagaries of the market: organic, fair-trade and biodiversity-friendly (or shade-grown). Although certified coffees still represent a small niche market, they have the potential to promote conservation and benefit the livelihoods of small producers. Especially under conditions of low international coffee prices, as those experienced in the first years of this century, these certification programs have contributed to the ecological and socio-economic stability of the coffee growing regions of northern Latin America.


3.
Libro
Stability of tropical rainforest margins: linking ecological, economic and social constraints of land use and conservation / Teja Tscharntke, Christoph Leuschner, Manfred Zeller, Edi Guhardja, Arifuddin Bidin, (eds.)
Disponible en línea: Stability of tropical rainforest margins: linking ecological, economic and social constraints of land use and conservation.
Tscharntke, Teja (editor) (1952-) ; Leuschner, Christoph (editor) ; Zeller, Manfred (editor) ; Guhardja, Edi (editor) ; Bidin, Arifuddin (editor) ;
Berlin, Heidelberg, Germany : Springer-Verlag Berlin Heidelberg , c2007
Disponible en línea
Clasificación: 634.928 / S8
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
ECO010011083 (Disponible)
Disponibles para prestamo: 1

4.
Artículo
*En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula
Linking shade coffee certification to biodiversity conservation: butterflies and birds in Chiapas, Mexico
Mas, Alexandre H. ; Dietsch, Thomas V. ;
Contenido en: Ecological Applications Vol. 14, no. 3 (June 2004), p. 642-654 ISSN: 1051-0761
Bibliotecas: San Cristóbal , Tapachula
Cerrar
SIBE San Cristóbal
B3331 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Tapachula
B2843 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula
Resumen en: Español |
Resumen en español

Shade coffee certification programs have emerged over the past six years to verify that coffee marketed as “shade grown” is actually grown on farms that provide higher quality habitat for biodiversity. In spite of good intentions and an increasing market, little consensus exists on whether current criteria can successfully identify coffee farms of conservation significance. This paper provides the first ecological evaluation and comparison of shade-grown coffee criteria used by major certification programs. Using vegetative data, we evaluated criteria developed by the Rainforest Alliance, the Smithsonian Migratory Bird Center (SMBC), and the Specialty Coffee Association of America across a range of coffee agroecosystems in Chiapas, Mexico, to determine which management practices each program would certify. Fruit-feeding butterflies and forest bird species found in these coffee agroecosystems were compared with nearby forest reserves as indicators of biodiversity and conservation potential. These agroecosystems fall into three categories: rustic, commercial polyculture, and shaded monoculture.

The rustic system contained significantly higher fruit-feeding butterfly diversity and an avifauna more similar to that found in forest reserves than the other systems. This was also the only agroecosystem that met the criteria for all certification programs, while the shaded monoculture fell short of all sets of criteria. This suggests that certification programs are succeeding in discriminating between the extremes of shade coffee production. Certification programs differed, however, in their treatment of the intermediate, commercial polyculture systems, reflecting different philosophies for conservation in managed ecosystems. Programs promoted by SMBC use high standards that would exclude all but the most diverse commercial polyculture or rustic systems to certify only those systems that support high levels of biodiversity. The program supported by the Rainforest Alliance only excludes the shaded monoculture while engaging the others in the move toward greater sustainability. The merits of each approach should be put to rigorous debate, and their ability to contribute to biodiversity conservation should be reflected in product marketing. This study suggests that further research can provide a stronger scientific basis and independent verification for the certification of green products that claim to enhance biodiversity conservation in tropical agroecosystems.


5.
Artículo
*En hemeroteca, SIBE-San Cristóbal
An index of management intensity for coffee agroecosystems to evaluate butterfly species richness
Mas, Alexandre H. ; Dietsch, Thomas V. ;
Contenido en: Ecological applications Vol. 13, no. 5 (October 2003), p. 1491-1501 ISSN: 1051-0761
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
B3332 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal

6.
- Artículo con arbitraje
PDF
Resumen en: Español | Inglés |
Resumen en español

Se ofrece una evaluación del campo de la biología conservacionista con el propósito de dilucidar por qué muchos esfuerzos conservacionistas han tenido un éxito muy limitado; se proponen enfoques alternativos que pueden ser de utilidad para hecer más efectiva a la disciplina. La discusión se centra en la impresión de que la biología conservacionista falla, generalmente, en poder reconocer que las inequidades sociales son muchas veces causales de degradación ecológica; esta falla se traduce muchas veces en investigaciones y programas conservacionistas ineficaces. Se hace una descripción sobre cómo el conocimiento en profundidad y la discusión explícita del trasfondo social de los problemas de conservación ambiental pueden mejorar la efectividad de las investigaciones científicas, sin comprometer el rigor del método científico; también se delinean tres técnicas concretas que pueden ayudar a alcanzar esta meta: observación participativa, construcción de coaliciones y abogacía.

Resumen en inglés

We offer an evaluation of the field of conservation biology with the intent of elucidating why many conservation efforts meet with limited success, and we propose alternative approaches that may be useful in making the discipline more effective. Our discussion centers on our sense that conservation biology generally fails to formally acknowledge that social inequalities among people are often (although not always) basal causes of environmental degradation. This failure often results in ineffective research and conservation programs. We describe how an in-depth understanding and explicit discussion of the social background of conservation problems can help improve the effectiveness of scientific inquiry, without compromising the rigor of scientific methods, and we outline three concrete techniques that may help accomplish this goal: participatory research, coalition-building, and advocacy.