Studies have documented biodiversity losses due to intensification of coffee management (reduc-tionPalabras Clave: agroecosistema, biodiversidad, café con sombra, café sin sombra, característico del sitio, meta análisis, producción de café

It has been documented that certain types of shade coffee plantations have both biodiversity levels similar to natural forest and high concentrations of wintering migratory bird species. These findings have triggered a campaign to promote shade coffee as a means of protecting Neotropical migratory birds. Bird censuses conducted in the El Triunfo Biosphere reserve in southern Mexico have confirmed that shade coffee plantations may have bird diversity levels similar to, or higher than, natural forest. However, coffee and forest differed in species composition. Species with a high sensitivity to disturbance were significantly more diverse and abundant in primary ecosystems. Neotropical migratory birds, granivorous and omnivorous species were more abundant in disturbed habitats. Insectivorous bird species were less abundant only in shaded monoculture. Foraging generalists and species that prefer the upper foraging stratum were more abundant in disturbed habitats, while a decline in low and middle strata foragers was found there. Findings suggests that shade coffee may be beneficial for generalist species (including several migratory species), but poor for forest specialists. Although shade coffee plantations may play an important role in maintaining local biodiversity, and as buffer areas for forest patches, promotion of shade coffee may lead to the transformation of forest into shade coffee, with the consequent loss of forest species.

Over the past decade, various strategies have emerged to address critical habitat losses through agricultural expansion. The promotion of shade-grown, premium-priced coffee has been highlighted as one alternative. Our research, based on interviews with farmers in Chiapas, disputes some of the assumptions made by shade coffee campaigners. Results revealed a predisposition to converting forest to shade coffee production due to the socioeconomic challenges farmers face and the potential for increasing incomes. To ensure that their well-being is improved at the same time as reducing environmental impacts, there is clearly a need to provide more detailed information on who is responsible for enforcing certification criteria and how this should take place.

In 1998, storms related to Hurricane Isis caused extensive gaps in the cloud forest of El Triunfo Biosphere Reserve in Chiapas, Mexico, where severe storms are infrequent. We examined how this disturbance affected bird species composition. Species richness and composition were similar both between pre-and post-disturbance forest and between newly created gaps and plots that remained forested after the hurricane. However, differences in response guilds were greater between pre-and post-disturbance plots than between forest plots with gaps after disturbance. Granivorous, omnivorous, and terrestrial species were more abundant before the hurricane, whereas insectivorous, midstory, and generalist foragers were more abundant after the hurricane. In addition, species with high sensitivity to disturbance were more abundant in the pre-disturbance forest, while low sensitivity species were more abundant after disturbance. In the post-disturbance forest, insectivorous species were most abundant in gaps and terrestrial-canopy foragers were most abundant in forest plots. Permanently open areas had significantly lower species richness, but had lowland generalist and second-growth species not present in the cloud forest. Results suggest that changes in species composition were not limited to the newly created gaps, but also affected the whole forest. The decline of high sensitivity species after disturbance supports the hypothesis that disturbance negatively affects specialists and benefits generalist species. Although there is evidence that natural communities tend to return to pre-disturbance conditions, changes in community structure could be aggravated if recurrent hurricanes occur before succession takes place. RESUMENEn 1998 tormentas asociadas al huracán Isis crearon huecos en el bosque de niebla de la Reserva de la Biosfera El Triunfo, Chiapas, México. Daños severos causados por tormentas son infrecuentes en estaárea. La riqueza y composición de especies fueron similar antes y después de la perturbación, así como entre los huecos creados por la tormenta y el bosque. Sin embargo, las diferencias en los gremios de respuesta fueron mayores entre pre-y post-perturbación que entre huecos y bosque después de la perturbación. Especies granívoras, omnívoras, y terrestres fueron más abundantes antes del huracán. Mientras que especies insectivoras, de sotobosque, y generalistas de estrato fueron más abundantes después del huracán. Además, especies con alta sensibilidad a la perturbación fueron más abundantes antes de la perturbación, mientras que especies con baja sensibilidad incrementaron después de la perturbación. Después del huracán, especies insectívoras fueron más abundantes en los huecos y especies forrajeras de terrestre/dosel fueron más abundantes en el bosque.Áreas con perturbación permanente mostraron una riqueza menor que el bosque, pero tuvieron especies generalistas y de crecimiento secundario no presentes en el bosque. Concluimos que los cambios en la composición de especies no se limitan a los huecos creados, sin...

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