Biological Crust Diversity Related to Elevation and Soil Properties at Local Scale in a Montane Scrub of Ecuador

**Background:** Ecuadorian montane scrublands (EMS) are biodiversity hotspots threatened by deforestation, overgrazing, and wildfires. Biological soil crusts (BSC)—communities of mosses, liverworts, lichens, cyanobacteria, fungi, and algae—play key roles in soil fertility, carbon and nitrogen cycling, and erosion prevention. However, the relationship between BSC diversity, elevation, and soil properties in tropical montane ecosystems remains poorly understood, particularly in South America. This study aimed to determine BSC diversity at three elevations (2100, 2300, and 2500 m.a.s.l.) in an EMS of southern Ecuador and its relationships with soil physical and chemical properties.

**Methods:** The study was conducted in Oña canton, Azuay province, Ecuador. Three elevations separated by ~200 m were selected. At each elevation, three 10 m × 10 m plots were established, each containing 20 quadrants of 30 cm × 30 cm (60 quadrants per elevation, 180 total). Lichens and bryophytes were identified using microscopy and standard spot tests. Soil samples (0–10 cm depth) were collected for bulk density, porosity, texture, pH, soil organic carbon (SOC), soil organic matter (SOM), total nitrogen (TN), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn). Statistical analyses included one-way ANOVA, generalized linear models (GLM), non-metric multidimensional scaling (NMDS), and PERMANOVA.

**Key Results:** A total of 35 species were recorded: 8 mosses, 2 liverworts, 2 cyanobacteria, and 23 lichens. Species richness was highest at E2 (28 species), followed by E3 (24 species) and E1 (19 species). Accumulation curves and Chao 2 estimator confirmed highest estimated richness at E2. Violin plots showed a bell-shaped distribution pattern for both richness and cover across elevations. Soil properties showed significant differences across elevations for pH (E1: 7.3±0.2, E2: 5.7±0.2, E3: 6.1±0.2; p=0.000), K (p=0.025), Mg (p=0.000), Ca (p=0.001), and Fe (p=0.000). Bulk density, porosity, sand, silt, clay, SOM, N, P, SOC, C/N ratio, Mn, Cu, and Zn showed no significant differences. GLM revealed that richness and cover were significantly influenced by elevation, pH, bulk density, K, Fe, and SOM. PERMANOVA showed elevation explained 38.9% of species composition variability (R²=0.389, p=0.001), with bulk density (R²=0.031, p=0.001), K (R²=0.022, p=0.001), Fe (R²=0.022, p=0.001), pH (R²=0.010, p=0.006), and SOM (R²=0.007, p=0.025) also significant. NMDS ordination showed clear clustering of BSC communities by elevation.

**Clinical Implications:** While not a clinical study, this research has implications for ecosystem conservation and land management. The bell-shaped diversity pattern suggests that intermediate elevations (around 2300 m) support maximum BSC diversity, making these zones priority areas for conservation. The significant influence of soil properties—particularly pH, bulk density, K, Fe, and SOM—indicates that soil degradation from anthropogenic activities (fires, deforestation, overgrazing) could directly reduce BSC diversity and its ecosystem functions. BSC loss may accelerate soil infertility by disrupting carbon and nitrogen fixation. The study provides baseline data for monitoring ecosystem health in anthropized montane scrublands and supports using BSC diversity as a bioindicator of environmental change in tropical montane ecosystems.