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Anthropogenic factors have significantly influenced the frequency, duration, and intensity of meteorological drought in many regions of the globe, and the increased frequency of wildfires is among the most visible consequences of human-induced climate change. Despite the fire role in determining biodiversity outcomes in different ecosystems, wildfires can cause negative impacts on wildlife. We conducted ground surveys along line transects to estimate the first-order impact of the 2020 wildfires on vertebrates in the Pantanal wetland, Brazil. We adopted the distance sampling technique to estimate the densities and the number of dead vertebrates in the 39,030 square kilometers affected by fire. Our estimates indicate that at least 16.952 million vertebrates were killed immediately by the fires in the Pantanal, demonstrating the impact of such an event in wet savanna ecosystems. The Pantanal case also reminds us that the cumulative impact of widespread burning would be catastrophic, as fire recurrence may lead to the impoverishment of ecosystems and the disruption of their functioning. To overcome this unsustainable scenario, it is necessary to establish proper biomass fuel management to avoid cumulative impacts caused by fire over biodiversity and ecosystem services.

Global climate drivers often have strong effects on the carrying capacity of animal populations, but little is known about how effects differ between regional and local scales. In this paper we evaluated how climate variables were correlated with regional and local fluctuations of a small rodent, Necromys lasiurus, in an Amazonian savanna. Between 2000 and 2019, we evaluated the temporal variation in abundance of N. lasiurus in eight 4.0-ha plots separated by 0.8 – 10.6 km. Using generalized linear mixed models, we found that, at a regional scale, the abundance of rodents captured was positively associated with the abundance in the prior year, but had little relationship with the Southern Oscillation Index (SOI), which had been shown to affect rats in a single plot in a previous study. However, variation in densities among years was coordinated among some plots, leading to patchiness in population dynamics. Based on the patterns of density fluctuations, the plots formed three clusters. Analyses based on these clusters indicated that only one was strongly affected by SOI, as in the previous study. The differences in the effects of global climate drivers on populations of a single species in relatively homogeneous habitat indicate that predictions about the effects of climate change should be based on simultaneous studies in a variety of sites or they may lead to spurious relationships.

We investigated the relative influences of vegetation cover, invertebrate biomass as an index of food availability and the short-term effects of fires on the spatial variation in densities of the rodent Bolomys lasiurus in an Amazonian savanna. Densities were evaluated in 31 plots of 4 ha distributed over an area of approximately 10×10 km. The cover of the tall grass (Trachypogon plumosus), short grass (Paspalum carinatum), shrubs and the extent of fire did not explain the variance in densities of Bolomys lasiurus. Food availability alone explained about 53% of the variance in B. lasiurus densities, and there was no significant relationship between insect abundance and vegetation structure. Fires had little short-term impact on the density of Bolomys lasiurus in the area we studied. As the species appears to respond principally to food availability, habitat suitability models based on easily recorded vegetation-structure variables, or the frequency of disturbance by fire, may not be effective in predicting the distribution of the species within savannas.

We investigated the effects of food availability, fire, and habitat structure on population rates of increase of the rodent Bolomys lasiurus in forty 4-ha plots distributed over an area of about 200 km2 in Amazonian savannas near Alter do Chão, Pará, Brazil. Mean rodent density over the entire study area declined by about one-half during the study period, despite largely independent density fluctuations within plots. Fires had no detectable association with density and population growth rates. Both densities and population growth rates were significantly associated with availability of invertebrate prey and a multivariate index of habitat structure. Invertebrate availability varied temporally within plots, and was not predictable from knowledge of vegetation structure or fire events.

We investigated the effects of food availability, fire, and habitat structure on population rates of increase of the rodent Bolomys lasiurus in forty 4-ha plots distributed over an area of about 200 km super(2) in Amazonian savannas near Alter do Chao, Para, Brazil. Mean rodent density over the entire study area declined by about one-half during the study period, despite largely independent density fluctuations within plots. Fires had no detectable association with density and population growth rates. Both densities and population growth rates were significantly associated with availability of invertebrate prey and a multivariate index of habitat structure. Invertebrate availability varied temporally within plots, and was not predictable from knowledge of vegetation structure or fire events.