Management impacts on fire occurrence: A comparison of fire regimes of African and South American tropical savannas in different protected areas

Abstract

Humans can alter fire dynamics in grassland systems by changing fire frequency, fire seasonality and fuel conditions. These changes have effects on vegetation structure and recovery, species composition, and ecosystem function. Understanding how human management can affect fire regimes is vital to detect potential changes in the resilience of plant communities, and to predict vegetation responses to human interventions. We evaluated the fire regimes of two recently protected areas in Madagascar (Ibity and Itremo NPA) and one in Brazil (Serra do Cipó NP) before and after livestock exclusion and fire suppression policies. We compare the pre- and post-management fire history in these areas and analyze differences in terms of total annual burned area, density of ignitions, burn scar size distribution, fire return period and seasonal fire distribution. More than 90% of total park areas were burned at least once during the studied period, for all parks. We observed a significant reduction in the number of ignitions for Ibity NPA and Serra do Cipó NP after livestock exclusion and active fire suppression, but no significant change in total burned area for each protected area. We also observed a seasonal shift in burning, with fires happening later in the fire season (October-November) after management intervention. However, the protected areas in Madagascar had shorter fire return intervals (3.23 and 1.82 years) than those in Brazil (7.91 years). Our results demonstrate that fire exclusion is unattainable, and probably unwarranted in tropical grassland conservation areas, but show how human intervention in fire and vegetation patterns can alter various aspects of the fire regimes. This information can help with formulating realistic and effective fire management policies in these valuable conservation areas.

Modeling the Influence of Eucalypt Plantation on Wildfire Occurrence in the Brazilian Savanna Biome

“…We found that human-related activities close to wildlands, especially agriculture and urban activities, seemed to promote wildfire occurrence. The explanatory variables were in agreement with other wildfire studies carried out in the Brazilian savanna [6,17,58,81] and also in accordance with the literature about modeling wildfire occurrence [20]. Croplands [82,83] or proximity to agricultural plots [60] are associated with a higher chance of fire ignitions due to the use of either machinery or traditional practices like slash-and-burn.…”

Resilience and restoration of tropical and subtropical grasslands, savannas, and grassy woodlands

“…Conversely, human-initiated fire management (implemented to increase visibility for hunting or to improve forage production), which is highly dependent on the local socio-cultural context (Alvarado et al, 2015), can result in fires that are more frequent or intense compared to historical fire regimes [e.g. through a change from cool burning, wet-season, lightning fires to hotter fires in the dry season (Ramos-Neto & Pivello, 2000;Rissi et al, 2017;Alvarado, Silva & Archibald, 2018)]. Given the high rates of woody encroachment in grasslands globally, the high resprouting capacity of old-growth grassland plants, and the dependence of grassland biodiversity on fire, we contend that increased fire frequencies are of far less concern for tropical grassland resilience relative to fire exclusion (Andersen et al, 2005;Parr et al, 2014;Durigan & Ratter, 2016).…”

“…While fire effects have been studied in the Cerrado (Hoffmann, 1996(Hoffmann, , 1998Miranda, Bustamente & Miranda, 2002), fire management is only starting to be explored more widely (Durigan & Ratter, 2016;Rissi et al, 2017;Schmidt et al, 2017;Alvarado et al, 2018;Schmidt et al, 2018) and mostly with a focus on responses of woody plants (de Medeiros & Miranda, 2005). A particular gap in restoration research, little is known about the role of fire in the reproduction and establishment of savanna grassland plants.…”

Contrasting human influences and macro-environmental factors on fire activity inside and outside protected areas of North America

“…PAs vary in management intensity and remoteness from human activities [36], and no PA is altogether free from anthropogenic influences [36][37][38]. However, PAs have been viewed as the best natural baseline from which to measure and monitor change or departures in fire regimes induced by humans [39,40]. The degree to which fire regimes in PAs are influenced by human activities versus environmental drivers at the continental scale remains largely unexplored.…”