The depletion of mineral reserves and consumption are the drivers of the rush for mineral extraction. The mining pressure is especially intense in developing countries, such as Brazil, whose economy is largely based on commodity exports. Being the second world's largest mineral producer (IBRAM, 2012), the mining sector has considerable economic and political influence in Brazil (Garcia et al., 2017). Although recent environmental disasters have demonstrated the vulnerability of the Brazilian environmental impact assessments and mineral extraction licensing processes, proposed changes in Brazilian mining legislation aim to facilitate mineral extraction (El Bizri et al., 2016; Fernandes et al., 2016). It has been argued that the development of widespread mining and dams in Brazil risks damaging its environmental conservation credentials (Ferreira et al., 2014). Moreover, Brazilian Government expects an increase of mineral production by 2030 (Brasil, 2010) which might further increase environmental impacts on biodiversity and ecosystem services provision.

We focus attention on the impacts of mining activities on species in a region where mineral extraction is one of the most important Brazilian economic activities: the eastern Brazil mountaintops. This region encompasses the Espinhaço range, a rich and diverse mountain range dominated by the rupestrian grasslands, an ecosystem that occurs on quartizitic or ferruginous soils and suffers high mining pressure (Fernandes, 2016). Mining has a direct effect on local habitat degradation through the removal of native vegetation and soil, as well as indirect effects by promoting changes at the landscape level, such as the opening of roads and secondary accesses, urbanization, deforestation for charcoal production, and intentional introduction of exotic species in rehabilitation projects (Fernandes, 2016; Sonter et al., 2014).

The Espinhaço range has the highest rates of plant endemism in South America (Fernandes, 2016) and high levels of endemism and diversity of amphibians (Leite et al., 2008). Recent descriptions of new anuran (Leite et al., 2012) and bird (Freitas et al., 2012) species in the Espinhaço indicate that many species, not yet known to science, might already be threatened. The Iron Quadrangle situated in the southernmost Espinhaço is also one of the world's largest gold and iron deposits (Lobato et al., 2001), accounting for 70% of the current Brazilian iron production (IBRAM, 2012). This region is also of utmost conservation concern (Silva et al., 2008) within the biologically rich Espinhaço, and has the highest anuran species richness level across the mountain range (Leite et al., 2008). More than 300 years of mineral extraction in the Iron Quadrangle have led to environmental contamination (Matschulla et al., 2007), with known impacts upon many endemic plant species (Jacobi et al., 2011). However, the impact of mining on the distribution range of the fauna in the Iron Quadrangle, and throughout the whole Espinhaço range, is still unknown.

Mountain species often have small and disjunct distributions, which may increase their vulnerability to ecological disturbances and increase their extinction risk (Harris and Pimm, 2008; Sobral-Souza et al., 2015). Small geographic range size has been found to be the best single predictor of extinction risk (Harris and Pimm, 2008). Mining activities in areas of high endemism and diversity are known to pose a considerable threat to local species (Jacobi et al., 2011), and may have a disproportionately high impact in high altitude ecosystems. These drivers may have wide-ranging consequences as highland species might not have the chance to colonize similar habitats due to limited dispersion capability, large distances between suitable habitats, hostile intervening terrain, or even non-existence of similar habitats (see Fernandes, 2016).

In this study, we aimed to assess the direct and indirect impacts of mining activities on anuran and bird species endemic to the eastern Brazil mountaintops, based on ecological niche models (ENM). ENM have been used to model species potential distributions by associating occurrence records and environmental variables, enabling the identification of potential habitat areas even when sampling is incomplete (Pearson, 2007; Peterson et al., 2011). Potential distribution maps can be used to evaluate the spread of potential threats within a species geographical distribution (Pena et al., 2014). We also measured the local biodiversity rate to assess the impacts of mining activities on regions that are suitable for a high richness of bird and anuran species. We hypothesized that a high proportion of the potential habitat available for both anuran and bird species endemic to the eastern Brazil mountaintops will overlap with areas that are currently directly and especially indirectly affected by mining.

The ENMs for all studied species predicted reliable and good distributions (the majority of TSS values were above 0.5). The anuran and bird species potential biodiversity maps showed a high richness rate in the central region of Minas Gerais State for both species groups, areas highly impacted by mining activities (Figs. 1 and 2).

Fig. 1.

The effects of mining activities on the estimated biodiversity rate for 41 anuran species, endemic to the eastern Brazil mountaintops. Polygons highlighted in gray represent mines officially approved and licensed for mining activity and their respective 5km radius buffer, which did not overlap areas estimated as suitable for anuran species. Histograms highlight the area directly and indirectly affected by mining in each richness class identified by the biodiversity rate estimate.

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Fig. 2.

The effects of mining activities on the estimated biodiversity rate for eight bird species, endemic from the eastern Brazil mountaintops. Polygons highlighted in gray represent mines officially approved and licensed for mining activity and their respective 5km radius buffer, which did not overlap areas estimated as suitable for bird species. Histograms highlight the area directly and indirectly affected by mining in each richness class identified by the biodiversity rate estimate.

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As we predicted, mining causes a profound effect on the potential habitat for mountaintop endemic anuran and bird species. More than 470 thousand square kilometers were estimated as suitable for anuran species, 32.33% of which are currently directly or indirectly affected by mining (S4 Table, Fig. 1).

The median proportions of anuran species potential range affected directly and indirectly by mining are 5.75% and 30.69%, respectively. Two anuran species (Scinax cabralensis and Bokermannohyla sagarana) have more than 35% of their ranges directly affected by mining, while eight species have more than half of their ranges impacted by the combined direct and indirect effects of mining (S3 Table). Bokermannohyla martinsi was the most affected anuran species, with 68.29% of the estimated habitat being directly and indirectly influenced by mining (Fig. 3). Considering the biodiversity rate estimated for all anuran species, we observed that 67% of the pixels with environmental characteristics suitable for 16 species (2109km2) are currently either directly or indirectly affected by mining (S4 Table, Fig. 1). The area estimated suitable for more than one anuran species is currently more directly and indirectly affected by mining (89,894km2 of overlapped area), than the area estimated suitable for only one species (64,324km2 of overlapped area) (S4 Table, Fig. 1).

Fig. 3.

The direct and indirect effects of mining on the potential distribution of Bokermannohyla martinsi. The histogram highlights the proportion of estimated suitable habitat area that are directly, indirectly and not affected by mining activities.

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Between the eleven rare anuran species (<10 occurrence points), all occurrence points of Aplastodiscus aff. cavicola (4), Corythomantis galeata (1) and Proceratophys redacta (2) are within the 5km buffer radius. Sphaenorhynchus canga has five of its six occurrence points being directly influenced by mining activities, and the remaining occurrence point is currently indirectly affected by mining. Pleurodema alium (2) and P. minuta (2) have half of their occurrence points within the indirect effects range of mining activities (S3 Table).

All assessed bird species are less directly affected by mining than the anuran species. However, all species are currently being directly and indirectly affected by mining (S5 Table). The median proportions of bird species potential range affected directly and indirectly by mining are 2.04% and 26.76%, respectively. More than 40% of the suitable habitat for Asthenes luizae (Fig. 4) and Augastes scutatus are currently either directly or indirectly affected by mining (S5 Table). When assessing the biodiversity rate for bird species, from more than 436 thousand square kilometers estimated as suitable for all bird species, 31% are currently indirectly or directly affected by mining (S6 Table, Fig. 2). 39% of pixels with environmental characteristics suitable for four species (53,541km2) are currently being affected by mining activities (Fig. 2, S6 Table).

Fig. 4.

The direct and indirect effects of mining on the potential distribution of Asthenes luizae. The histogram highlights the proportion of estimated suitable habitat area that are directly, indirectly and not affected by mining activities.

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All the endemic mountaintop bird and anuran species assessed in this study are affected by mining, at least indirectly. Eight anuran species have already had more than 50% of their ranges affected at some degree by mining, and B. martinsi was estimated to have almost 70% of its range affected at some degree by mining. More than 40% of the suitable habitat for A. luizae and A. scutatus are currently being influenced by mining activities. If other threats to the rupestrian grasslands are considered, such as climate change, habitat degradation by fire, livestock, tourism, road construction, agriculture and Eucalyptus plantations (Fernandes, 2016), the situation of the endemic anuran and bird species is even more worrisome.

The estimated suitable habitat area for 17 anuran and one bird species is less than 20,000km2. Considering the Criteria B from IUCN Red List (IUCN, 2016) alone, these species can be classified as Vulnerable (<20,000km2) or Endangered (<2000km2). More than 60% of the estimated suitable habitat for S. cabralensis (1654km2) and B. sagarana (2458km2) is currently being influenced by mining. Further, all the occurrence points of three rare anuran species are within the 5km range of influence of mining activities, and almost all occurrence points of Sphaenorhynchus canga​ are currently directly affected by mining. Between the assessed bird species, 33.25% of the 2233km2 estimated as suitable for Asthenes moreirae are currently under the influence of mining activities. As mountaintop species are already known to be more prone to extinction events due to habitat loss (Stuart, 2004) and climate change (Şekercioğlu et al., 2008), small range mountaintop species may be at major risk of extinction over the coming decades. Furthermore, some of the anuran species in this study have only recently been described (e.g.: Leite et al., 2012). Therefore, it is urgent a detailed assessment of the conservation status of bird and anuran species endemic to the eastern Brazil mountaintops, considering mining expansion as a major threat for these species.

More than 30% of the area considered as suitable for bird or anuran species are currently under pressure by mining activities. When assessing the biodiversity rate maps for both species groups, pixels estimated suitable for more than 2 bird and anuran species are highly affected by mining. 2897km2 have suitable environmental characteristics for four bird species, only 0.66% of the suitable habitat area for all bird species. However, more than 43% of this area is currently being either directly or indirectly affected by mining. Considering anuran species, the area estimated suitable for more than one species is currently more directly and indirectly affected by mining than the area estimated suitable for only one species. 2109km2 (only 0.45% of the suitable area estimated for all anuran species) have suitable environmental characteristics for 16 different anuran species, 67.47% of which are under pressure of mining activities. Those areas, which can be considered as biodiversity hotspots of endemic mountaintop bird and anuran species, should be considered priority areas for conservation.

Mining affects species by destroying, fragmenting, and degrading natural habitats, releasing toxic wastes (Gentes et al., 2007) and altering land-use dynamics in mined regions (Sonter et al., 2014). Geomorphological aspects, which attract mining to mountain areas, spatially overlap with the areas of high endemism associated to high elevations. Because of the political and economic power of the mining sector, decision makers have often prioritize mining over conservation. While in other biomes the proposals of biodiversity offsetting may be a good conservation compromise, these offsetting initiatives are more difficult to implement in mountainous areas, because these habitats are naturally patchy (Sonter et al., 2014).

Mineral exportation is one of Brazil's economic cornerstones, and it is expected to further expand by 2030 to meet global demands for iron, gold, copper and other minerals. This will place more pressure for exploiting mineral reserves, and if current policies are adopted this shall overlook the impact of mining on biodiversity. Considering anuran and bird species endemic to the eastern Brazil mountaintops, mining already impacts more than 40% of the suitable habitat for 13 species. If other threats are considered such as fire, pasture development, agriculture, forest plantations and climate change, it is very likely that many species will become extinct in a near future. As all species studied here are endemic, local extinction means global extinction. Currently, there are thousands of square kilometers of areas within Brazilian conservation units with approved mines or being considered for mineral extraction (Ferreira et al., 2014). Therefore, to avoid or mitigate the impacts of mining activities on mountaintop endemic species, it is essential to undertake a task force aimed at mapping ecological and conservation attributes in mountaintops, especially in mining regions. This will help design management practices in order to reconcile socio-economic and environmental needs.