Interactions between climate and land-use change may drive widespread degradation of Amazonian forests. High-intensity fires associated with extreme weather events could accelerate this degradation by abruptly increasing tree mortality, but this process remains poorly understood. Here we present, to our knowledge, the first field-based evidence of a tipping point in Amazon forests due to altered fire regimes. Based on results of a large-scale, longterm experiment with annual and triennial burn regimes (B1yr and B3yr, respectively) in the Amazon, we found abrupt increases in fire-induced tree mortality (226 and 462%) during a severe drought event, when fuel loads and air temperatures were substantially higher and relative humidity was lower than long-term averages. This threshold mortality response had a cascading effect, causing sharp declines in canopy cover (23 and 31%) and aboveground live biomass (12 and 30%) and favoring widespread invasion by flammable grasses across the forest edge area (80 and 63%), where fires were most intense (e.g., 220 and 820 kW·m −1 ). During the droughts of 2007 and 2010, regional forest fires burned 12 and 5% of southeastern Amazon forests, respectively, compared with <1% in nondrought years. These results show that a few extreme drought events, coupled with forest fragmentation and anthropogenic ignition sources, are already causing widespread fire-induced tree mortality and forest degradation across southeastern Amazon forests. Future projections of vegetation responses to climate change across drier portions of the Amazon require more than simulation of global climate forcing alone and must also include interactions of extreme weather events, fire, and land-use change.forest dieback | fireline intensity | stable states | MODIS | fire mapping

The increasing use of species distribution modeling (SDM) has raised new concerns regarding the inaccuracies, misunderstanding, and misuses of this important tool. One of those possible pitfalls − collinearity among environmental predictors − is assumed as an important source of model uncertainty, although it has not been subjected to a detailed evaluation in recent SDM studies. It is expected that collinearity will increase uncertainty in model parameters and decrease statistical power. Here we use a virtual species approach to compare models built using subsets of PCA-derived variables with models based on the original highly correlated climate variables. Moreover, we evaluated whether modelling algorithms and species data characteristics generate models with varying sensitivity to collinearity. As expected, collinearity among predictors decreases the efficiency and increases the uncertainty of species distribution models. Nevertheless, the intensity of the effect varied according to the algorithm properties: more complex procedures behaved better than simple envelope models. This may support the claim that complex models such as Maxent take advantage of existing collinearity in finding the best set of parameters. The interaction of the different factors with species characteristics (centroid and tolerance in environmental space) highlighted the importance of the so-called “idiosyncrasy in species responses” to model efficiency, but differences in prevalence may represent a better explanation. However, even models with low accuracy to predict suitability of individual cells may provide meaningful information on the estimation of range-size, a key species-trait for macroecological studies. We concluded that the use of PCA-derived variables is advised both to control the negative effects of collinearity and as a more objective solution for the problem of variable selection in studies dealing with large number of species with heterogeneous responses to environmental variables.

Aim  We evaluated Odonata distribution data and predicted the compositional resemblance based on niche‐based species distribution models to analyse the following questions: (1) How is estimated species richness distributed, and how can it be preserved under the actual network of conservation units (a gap analysis approach)? (2) How is the estimated odonate beta diversity distributed, and is there a better distribution of conservation units (a priority setting approach)? (3) Is the probability of being under protection a function of the potential species range size? and (4) Will the current conservation network proposals protect odonate taxa? Location  Central Brazil in a core Cerrado area. Methods  We generated odonate species distribution predictions based on MaxEnt and maps derived from estimated species richness, beta diversity and gap analysis for all species predicted to occur in the study area. Then, we compared these maps with current conservation units, land‐use patterns and proposals for the establishment of conservation units. Results  Raw odonate species records provided limited utility for setting conservation priorities without the use of niche‐based models. However, area under the receiver operating curve (AUC) values were characterized by substantial variation that was related to the number of records. No current conservation units overlapped the areas with higher predicted richness and beta diversity, and in general, conservation units were not preserving restricted/rare species. There was a direct linear correlation between species range size and the proportion of its range protected in the current network of conservation units. Finally, we identified three areas with high odonate beta diversity where conservationist actions should be implemented. Main conclusions  Current conservation units and future suggested areas do not overlap regions with high conservation values for odonates. Conservation units protect species at random, and the level of protection has a direct relationship with species range size; thus, wide‐range species are expected to be more protected than restricted or threatened species.

Mountain endemic species are usually related to a restricted set of ecological conditions, presenting a fragmented range interspersed by lowland that may prevent its dispersion and favors isolation and speciation. Here we investigate the pattern of distribution of Melipona capixaba, an endemic bee species of mountain areas of central Atlantic forest by means of species distribution modeling procedures. We aimed to describe the potential distribution of this species considering broad climatic variables and evaluate the possible non-equilibrium of its range using models that simulate restricted dispersion by inclusion of spatial variables. The models indicate that the known occurrence points are located in a small fraction of its potential distribution, which is fragmented in different mountain ridges. Models without spatial variables predicted a larger range and an overlap with the distribution of a closely related species, M. scutellaris. Ensemble models also indicate areas to future search for new population of this species, as well as important areas for its conservation.

Brazilian indigenous lands prevent the deforestation of the Amazon rainforest while protecting the land rights of indigenous peoples. However, they are at risk because they overlap with large areas of registered interest for mining. Indigenous lands have been in the spotlight of the pro-development wing of the parliament for decades, and the current president of Brazil, Jair Bolsonaro, promised that he would open up these territories for exploitation. Recently, bill PL191/2020 was released to downgrade the protection status of indigenous lands by regulating mining activities in these territories. Mining operations have an unavoidable socio-environmental impact on indigenous communities that is difficult to compensate. First, rapid demographic growth associated with the incoming migrant workforce often causes social disruption and threat indigenous societies. Moreover, sustained pollution related to mining procedures and accidental spills largely degrade the environment and imperil indigenous health. Finally, mining operations drive deforestation both within and beyond their operational boundaries. Mining is already an essential determinant of forest loss in the Amazon, where further deforestation may result in extended droughts with significant social and economic consequences. We conclude that, if mining operations were allowed in Brazilian indigenous lands, indigenous peoples would be imperiled along with regional and global climate and economies.

The infraorder Gerromorpha comprises semiaquatic bugs, most of which spend much of their lifetime on the water surface, between floating plants, or on the margins of water bodies. Based on literature and collections made on streams and lakes on municipalities of eastern Mato Grosso, Brazil, a list has been elaborated with 52 species, including several new records. Out of the recorded species, 26 belong to the family Veliidae, 20 to Gerridae, three to Hydrometridae, two to Mesoveliidae, and one to Hebridae. The modeling of the potential geographical distribution is also presented for the 20 species that have been recorded for the first time from the state.

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Protected areas (PAs) are vital for the conservation of Brazil's biodiversity (Barber et al.2014). However, they are at risk of a downgrade in legal status due to economic pressures on natural resources (Bernard et al.2014; De Marques & Perez 2014; Pack et al.2016). Mining is one of the most urgent environmental threats in Brazil (Ferreira et al.2014; El Bizri et al.2016), with plans in place for a 10-fold increase in the number of mining projects in c. 8 years. If all were developed, the Brazilian territory occupied by mining would increase 23-fold in the near future. Currently, 12 697 projects covering 98 × 105 ha are planned within PAs. Licensing and exploitation of 53% of this land will depend on the approval of three bills that intend to authorize mining in areas where it was formerly forbidden. Here, we analyse the potential consequences of the approval of these new policies for conservation.