Lichen diversity, indicator species, and community turnover along a fog oasis–Andean gradient in Peru: a baseline for climate change biomonitoring

Lichens are sensitive bioindicators of environmental change, yet their diversity patterns remain poorly documented in the hyperarid ecosystems of southern Peru. This study characterizes, for the first time, lichen diversity, community composition, and indicator species along a coastal-Andean altitudinal gradient (683–3,756 m a.s.l.) encompassing fog oases (lomas) and high-Andean shrublands in Moquegua, a region facing increasing pressure from large-scale copper mining and projected climate change impacts. We established 175 sampling units across 35 stations in seven sectors, identifying 53 lichen species belonging to 33 genera, 13 families, 10 orders, and 3 classes (Lecanoromycetes, Candelariomycetes, and Arthoniomycetes). Alpha diversity indices (Shannon, Simpson, Pielou) were compared between ecosystems using Wilcoxon and t-tests, community composition was analyzed through NMDS and PERMANOVA, environmental predictors were evaluated using GLM and LM, and indicator species were identified with the IndVal.g index. Simpson diversity was significantly higher in Andean shrublands than in coastal fog oases (0.83 ± 0.06 vs. 0.75 ± 0.09; p = 0.029), while Pielou's evenness showed highly significant differences (0.90 ± 0.06 vs. 0.77 ± 0.08; p < 0.001). Remarkably, community composition showed complete species turnover between ecosystems (β-diversity = 1), with 28 species exclusive to coastal fog oases and 25 species exclusive to Andean shrublands—a pattern rarely documented in lichenological studies. PERMANOVA confirmed highly significant compositional differences at both ecosystem (R² = 0.280, p = 0.001) and sector (R² = 0.765, p = 0.001) levels. Altitude and climatic zone emerged as the primary environmental predictors, explaining 60.9% of Shannon diversity variance. Thirty-four indicator species were identified with significant ecological fidelity (p ≤ 0.05), including Umbilicaria polyphylla (IndVal = 0.980) for Andean shrublands and Flavopunctelia flaventior (IndVal = 0.707) for coastal fog oases.