The role of fire in the vegetation dynamics of upland savannas of the Venezuelan Guayana

Abstract

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.

Can savanna burning projects deliver measurable greenhouse emissions reductions and sustainable livelihood opportunities in fire-prone settings?

“…As part of traditional practice, fire is used for such purposes as clearing forest for cultivation and for paths, visual communication, deterring dangerous animals, to facilitate hunting and fishing, to cure illnesses, and to reduce fuel loads for the prevention of large catastrophic fires (Mistry et al 2005;Rodríguez and Sletto 2009;McDaniel et al 2005;FIEB 2007;Bilbao et al 2009;Pivello 2011). 4.2 Potential for emissions abatement fire management projects in south American savannas-an example from Venezuela…”

“…Annually, there are from 1000 to 3000 wildfires in the park that burn approximately 5700-7500 ha (EDELCA 2004); 73 % of these begin in savanna areas and usually reach riparian and forest margins (Ablan et al 2005). Potentially severe impacts from these fires include: the loss of buffer capacity to withstand extreme climatic events, soil degradation, changes in the water balance, degradation of landscapes that attract tourists, increased sediment loading of watercourses, alteration of biogeochemical cycles, and loss of biodiversity (Bilbao et al 2009(Bilbao et al , 2011.…”

Linking well-being with cultural revitalization for greater cognitive justice in conservation: lessons from Venezuela in Canaima National Park

“…Furthermore, it showed that the variability in fire behavior, in turn, creates a mosaic of grassland patches with different fire histories, where the recently burned patches act as firebreaks in the propagation of fires that are started in neighboring patches. Based on this research, the authors concluded that the Pemon prescribed burning system reduces the occurrence of dangerous fires and furthers spatial and temporal vegetation heterogeneity (Bilbao et al 2009(Bilbao et al , 2010. Most importantly, this study provided support for Pemon prescribed burning as an appropriate technique for biodiversity conservation and suggested that rather than eliminating Pemon fire management practices, the Pemon burning system is key in preventing potentially large destructive fires in critical conservation areas.…”

“…Since fire is considered to be one of the key risk factors in the Gran Sabana (Bilbao and Vessuri 2006), the project also initiated a paleoecological reconstruction of the landscape history (Leal 2010, Leal et al 2016, an analysis of changes in the vegetation cover and land uses, and a study of fire behavior and its impacts in the Gran Sabana (Bilbao et al 2009(Bilbao et al , 2010 [2] . Results of these studies were presented and discussed at various community assemblies that were part of the joint research activities, which prompted important discussions about the historical and social factors that have caused landscape change in the area.…”

“…This counter-narrative of fire has been steadily finding its way into public discourse, through (a) academic publications (Bilbao et al 2009, Leal 2010, Leal et al 2016, (b) the organization of symposia and plenary discussions in congresses (García and Bilbao 2007), (c) discussions in local, national, and international training courses, and (d) popular publications via the national media, the international press, and the internet (Romero 2010, Morillo 2011, Barras 2015.…”