Saxicolous lichen communities in three basins associated with mining activity in northwestern Argentina

Abstract

Mining activity affects the vegetation and soils of the ecosystems. However, the effects of mining activity on saxicolous lichen communities are less concerned. Thus, the aim of this study was to characterize saxicolous lichen communities in three basins (Vis-Vis River basin, Poteros River basin, and Capillitas River basin) surrounding metalliferous mining projects of different types of operation and at different stages of exploitation. A large-scale mine (Bajo de la Alumbrera) with more than 25 a of open-pit mining located in the Vis-Vis River basin (CRV). A pre-exploitation mine (Agua Rica) located in the Poteros River basin (CRP), and a small-scale mine (Minas Capillitas) with more than 160 a of underground mining located in the Capillitas River basin (CAC). In each basin, species richness, cover, and frequency of lichen communities were measured on 40 rock outcrops. Also, explanatory variables were recorded, i.e., altitude, slope, aspect, vegetation cover, rock, and soil cover around the rocky area sampled. Richness and total cover of lichen communities were analysed using linear models, and species composition was explored using multivariate ordination analysis. Results showed that a total of 118 lichen species were identified. The species richness differed among basins and the lichen composition present in areas close to mining sites responded mainly to basins, altitude, and microsite variables. The lichen cover showed no difference among basins, but it changed under different rock and vegetation cover. It was not possible to quantify the effects of mining activity on species richness and composition. However, the low richness values found in the downstream of Minera Alumbrera could be associated with the negative impact of open-pit mining. Moreover, the effects of large-scale mining activity on lichen communities needs more investigation.