Long-term, fire-induced changes in habitat structure and microclimate affect Cerrado lizard communities

Abstract

Fire transforms the structure of natural habitats and, consequently, modifies microclimates affecting ectotherm organisms that are particularly susceptible to changes in the thermal environment. Nevertheless, the effects of fire-induced microclimatic shifts upon natural populations have been neglected. We measured the central tendency and variation of habitat structural and microclimatic variables in experimental plots of Neotropical savanna vegetation subjected to different fire regimes (control, biennial/early dry season, biennial/mid dry season, biennial/late dry season, quadrennial/mid dry season; one 10 ha replicate of each) and assessed their effects upon lizard community structure (15 species). In addition, we evaluated the underlying mechanisms linking fire-induced environmental changes to community structure, by comparing lizard body condition and survival between different fire regimes. A guided regularized random forest (GRRF) analysis indicated that fire suppression promoted increased tree density, canopy cover and leaflitter weight, whereas burning had the opposite effects, reducing the habitat structural complexity. A redundancy analysis (RDA) indicated that (1) the best predictors of fire regimes were means of structural variables, but variances of microclimatic variables and (2) the reduced structural complexity of burned plots both increased and decreased the variation of microclimatic variables. A canonical correspondence analysis (CCA) revealed that lizard community structure was chiefly influenced by a gradient of decreasing tree density, canopy cover and leaf litter weight with increasing fire severity. About half of the lizard species were favored in the fire-protected plot, while the other half was favored in the burned plots, with most of the variation being explained by structural variables. Lizard body condition and survival rates were not affected by fire regimes, suggesting a dominant role of thermoregulation opportunities afforded by habitat structure-instead of food availability or predation rates-upon community structure. Our findings indicate that even sporadic fires can have profound effects upon lizard communities and that protecting some habitat patches from burning is essential to maximize lizard diversity in Cerrado landscapes.

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

“…So, the homogenization of vegetation structure, as seen in the case of increased woody encroachment in the absence of fire, affecting grassland/savanna specialists (Vieira and Marinho-Filho, 1998;Vieira, 1999;Henriques et al, 2000Henriques et al, , 2006Briani et al, 2004;Maravalhas and Vasconcelos, 2014;Abreu et al, 2017), will disrupt community structure resulting in biodiversity losses. Studies of open formations around the world also highlight the importance of habitat heterogeneity for maintaining biodiversity of the landscape (Andersen et al, 2012;Beale et al, 2018;McCleery et al, 2018;Bond, 2019;Costa et al, 2019). At our study area, open grasslands and savannas have particular importance for conservation at local and regional scales.…”

“…Despite the pattern of low impact on richness observed in most studies, however, there are some exceptions when fire effects are analyzed at a small scale, comparing different pieces of the vegetation mosaic. Costa et al (2019) found half the lizard species favored in unburned plots while the other half was favored in burned plots. These results indicate that maintaining the vegetation mosaic can enhance beta and gamma diversity, a recommendation supported also by Andersen et al (2012), who found advantage for small mammals in preserving some large infrequently burned areas.…”

“…Vieira and Marinho-Filho, 1998;Layme et al, 2004;Prada and Marinho-Filho, 2004). Recent studies, however, have shown fire influences other than changes in richness, such as body conditions of lizards, which depend on habitat preferences of different species (Costa et al, 2019). Such differences deserve further investigation for other groups.…”

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

“…First, the primary effects of fire are indirect through habitat change, which is caused by both individual fires and by different fire regimes. This has been shown for many biomes for a wide range of animal taxa, including ants (Andersen, 2019), reptiles (Costa et al, 2020;Dixon et al, 2018), birds (Gosper et al, 2019;Woinarski & Recher, 1997) and small mammals (Griffiths & Brook, 2014). In particular, fire has a pervasive effect on fauna through its impact on habitat openness (Andersen, 2019).…”

Biodiversity and conservation of the Cerrado: recent advances and old challenges

“…Human-induced environmental impacts also translate into increased frequency and severity of fires in the Cerrado. Costa et al (2020) assessed the effects of fire-induced microclimatic shifts upon Cerrado lizard communities. They found that fire suppression enhanced habitat structural complexity, whereas burning had the opposite effects; half of the lizard species were favoured in the fire-protected plot, while the other half was favoured in burned plots.…”