In Canaima National Park (CNP), Venezuela, a protected area inhabited by the Pemón people, sociocultural and demographic changes have contributed to the apparent unsustainable use of fire, leading to forest and habitat loss. This over-use of fire, together with increased forest vulnerability to fire as a result of global climate change, could put both ecosystems and human well-being at risk. The conflict over fire use derives from the fact that whereas the Pemón depend for their livelihood on the use of fire for shifting cultivation and hunting, the policy of the CNP government agencies is fire exclusion (although this is not effectively enforced). Nevertheless, recent ecological studies have revealed that the creation of a mosaic of patches with different fire histories could be used to create firebreaks that reduce the risk of the wildfires that threaten the vulnerable and diverse savanna-forest transition areas. This technique imitates the traditional cooperative savanna burning strategies of the Pemón. By linking research on knowledge systems with management policies, the impasse over fire in the CNP might be avoided.

The frequent occurrence of ®res in Canaima National Park, Venezuelan Guayana, is of great concern in the region. Fire, mostly originating on savannas, is considered a threat because of its impacts upon ecosystems, triggering a process of forest substitution by treeless savannas. In addition, the ®res aect the well-being of Pemo n indigenous communities, the hydroelectrical industry, and activities carried out by institutions and other stakeholders in the CNP. Here we present the main results of a long-term study of ®re behavior and ®re eects on biodiversity and biomass production in savanna ecosystems of the CNP. We simulated Pemo n traditional methods of ®re management by burning a series of 31 savanna plots in dierent periods of the dry season over a seven-year period. We demonstrate that (a) ®res can occur under a wide range of weather conditions and fuel characteristics, which in turn lead to a high variability in ®re intensities, temperatures and spread rates,¯ame lengths, burn eciencies, and ash production; (b) wind speed and ®ne fuel load constitute the principal drivers of ®re behavior; and, (c) opposite to what was long believed, ®res never reach an annual frequency but occur every 2, 3, or 4 years, due to the low recovery rates of the vegetation. Because ®re could lead to a variety of scenarios depending on the amount of biomass (176±1,271 g m À2 ), live/dead ratios (0.36±3.60) and biodiversity (species abundance and composition), we believe that patch mosaic burning can be used as a management tool for biodiversity conservation and to reduce the risk of hazardous wild®res by creating a patchwork mosaic with dierent ®re histories to generate heterogeneity across space and time. This practice would not only help preserve dierent ecosystems but also the sustainable use of natural resources by the Pemo n people in the park.

The concept of reflexive governance has to a large extent emerged from an increasing recognition of the need to consider different meanings of nature in the environmental policy-making process. Yet, so far, little attention has been paid to creating conditions for reflexive governance among different actors in intercultural settings, particularly in the context of environmental conflict and strong cultural change among indigenous peoples. This paper reviews three participatory research projects carried out in the Gran Sabana in Canaima National Park, Venezuela, which facilitated dialogue among indigenous people regarding their conflicting views of fire, in part by developing community-wide critical reflections on processes of cultural change and identity formations. These experiences suggest that once marginalized environmental knowledge is publicly acknowledged within the context of endogenous cultural processes, indigenous people feel more confident to engage in dialogue with other actors, thus allowing the emergence of reflexive environmental governance.

Fire is considered a major threat to forest conservation in the Neotropics. Palaeoecological studies are critical for understanding the long-term interactions of climate, fire, and human activities in the savanna-forest dynamic. Here, new data from palynological analyses conducted in sedimentary records from the northern edge of the Amazon Basin, the Gran Sabana, southeast of Canaima National Park (CNP) are presented. Four radiocarbon ages from Quebrada Kowana (QK) and two for Ariwe Fernland (AF) records showed that both are late-Holocene age (with extrapolated basal ages of 3100 and 3400 cal. yr BP, respectively). Both showed the occurrence of gallery forest until 1800 (QK) and 1600 (AF) cal. yr BP, with forest taxa reaching 60% and 40% of the terrestrial pollen sum, respectively. The main forest taxa were Celastraceae, Moraceae/Urticaceae, Schefflera, Protium, and Mahurea (QK) and Dimorphandra, Protium, Schefflera, Tachigali, and Blepharandra (AF). Savanna herbs (mainly Poaceae) reached 40-50% (QK) and 60% (AF). The high abundance of savanna herbs together with the low occurrence of mature forest taxa, and high abundance of pioneer taxa, suggests that the former forests comprised very open and disturbed forest-belts, surrounded by savannas. Since 1800 (QK) and 1600 (AF) cal. yr BP, forest taxa dropped to 10% and 5%, respectively, suggesting the substitution of forests by herbaceous communities. The high abundance of charcoal recorded from the beginning of the records to about 1800-1600 cal. yr BP suggests that recurrent fires spreading from neighboring savannas were reaching the former forest, causing compositional changes and triggering forest reduction. Fires were very likely human-made, but highly controlled by climate. Hence, forest substitution happened when a combination of local fires and droughts was given in every record. Results agree with those from other localities in the CNP in confirming the occurrence of regional-scale gallery forest degradation during the late Holocene.

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Introducción: Los cigarrillos electrónicos, introducidos en el mercado en el 2003 y con gran acogida comercial desde entonces, se han convertido en un dispositivo que puede igualar o superar el riesgo del cigarrillo de combustión respecto a múltiples desenlaces nocivos para la salud. A pesar de ello, estos dispositivos se perciben como menos lesivos o adictivos, y son más aceptados socialmente. Esta nueva práctica ha sido especialmente acogida por la población adolescente, época de la vida en la que existe una mayor vulnerabilidad debido a su proceso de neurodesarrollo. Objetivo: Realizar una revisión temática de los cigarrillos electrónicos, sus políticas de regulación, sus patrones de consumo y sus asociaciones con la salud mental. Métodos: Se realizó una búsqueda de estudios secundarios, en PubMed y SciELO, utilizando términos MeSH (o DeCS) y libres. Posteriormente, se revisaron los artículos obtenidos y se filtraron teniendo en cuenta los temas que se iban a evaluar. Después de realizar el proceso de tamización, se obtuvieron 54 artículos. Discusión: Se describe la influencia de la nicotina en el desarrollo cerebral del adolescente, así como la tendencia del consumo de cigarrillos electrónicos y las medidas regulatorias que se han implementado. El riesgo elevado para la salud mental de los adolescentes que representan los cigarrillos electrónicos, sumado a una pobre regulación en Colombia, genera la necesidad de fortalecer los sistemas de prevención e intervención para el consumo de nicotina, así como políticas comerciales más rigurosas frente a su venta en diferentes modalidades.

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