No Net Loss of Species Diversity After Prescribed Fires in the Brazilian Savanna

Abstract

Although savannas are fire-adapted ecosystems, prescribing fire for biodiversity conservation remains controversial at least in some regions where savannas occur. Faced with uncertainty, many decision makers and even scientists are still reluctant to prescribe fire for conservation purposes in fire-prone ecosystems, invoking the precautionary principle. Knowledge gaps on the ideal fire regime, such as how and when to burn, and especially the fear of biodiversity losses, are among the main arguments against fire management applied to remnants of native savanna vegetation. To inform this debate, we assessed the impact of prescribed fires on diversity of plants (different growth forms), ants, frogs, lizards, birds, and small mammals, in savannas and grasslands of the Brazilian Cerrado. We assessed the existing species richness, composition, and abundance in areas subjected to long periods of fire suppression and compared to that observed over a short period after prescribed dry-season fires, within each group of plants and animals. Whenever possible, we carried out separate analyses for grassland and savanna. Burning did not significantly reduce species richness of any of the groups analyzed, but had a positive effect on richness of graminoids in grassland. When analyzed at the species level, abundance of most animal groups did not show consistent responses to fire, except for a decrease in some frog populations in grasslands. Forbs, graminoids, and subshrubs increased in abundance after fire in grassland areas, though in savanna areas, abundance of forbs, and subshrubs tended to decline after fire. Species composition changed little in response to fire as indicated by low levels of dissimilarity between burned and unburned areas. These results confirm the high resilience of Cerrado biota to fire, as expected for savanna ecosystems in general. Besides, we demonstrate here that the risk of biodiversity losses cannot justify the objections to the use of prescribed fire for conservation purposes in the Cerrado.

A review of fire effects across South American ecosystems: the role of climate and time since fire

“…Biodiversity was not significantly affected by fire across any taxa group, climate type, or time since fire, indicating an overall high resilience at the analyzed spatial and temporal scales. This is in line with previous studies focused on specific semiarid regions, including two wellstudied large fire-prone ecosystems in South America (i.e., Cerrado and the Gran Chaco), which had shown post-fire recovery of biodiversity for different taxa groups, such as plants, birds, and insects (e.g., Kunst et al 2003Kunst et al , 2015Kowaljow et al 2019;Durigan et al 2020;Pilon et al 2021). However, these responses may certainly involve context-dependent changes in species composition (Durigan et al 2020;McLauchlan et al 2020), which could not be captured in our quantitative synthesis.…”

“…6C). The early vegetative response reflects the high resprouting capacity of many shrub species across the studied regions, especially in fire-prone regions (Gurvich et al 2005;Bravo et al 2014;Torres et al 2014;Durigan et al 2020;Jaureguiberry et al 2020). Regarding the reproductive response, the pattern reported here agrees with previous evidence suggesting that shrubs might reach minimum reproductive sizes soon after fire, then slow down their growth rate and reproduction as succession progresses (Hoffmann and Moreira 2002;Hoffmann and Solbrig 2003;Galíndez et al 2009).…”

Faunal responses to fire in Australian tropical savannas: Insights from field experiments and their lessons for conservation management

“…A study of bird responses to a large fire elsewhere in Kruger found that species richness and composition did not vary with fire intensity, and it was concluded that bird communities are likely to be robust to all but the most extreme fire regimes (Mills, 2004). The Brazilian savanna fauna is likewise highly resilient to fire (Durigan et al, 2020).…”

Responses of Plant Biomass in the Brazilian Savanna to Frequent Fires

“…On the one hand, biennial fires negatively affect tree and shrub biomass, on the other hand herbs and grasses need to be managed with fire in order to maintain the biodiversity and functioning of the ecosystem (Pinheiro and Durigan, 2009;Abreu et al, 2017;Durigan et al, 2020). As such, we suggest the use of prescribed burns in mosaic configurations with different fire frequencies (no fire and quadrennial fires).…”