Plant Distillates Suppress Lampenflora in Karst Caves: Insights From In Situ Experiments and Microbial Community Analyses.

Lampenflora (cyanobacteria, algae, mosses) threaten karst caves by accelerating bioweathering and damaging speleothems. Conventional control methods are often environmentally harmful or unsustainable. This study evaluated plant distillates from Artemisia argyi (AA), Cinnamomum cassia (CC) and Mentha canadensis (MC) for inhibiting lampenflora in Zhijin Cave, China. In situ plot experiments over 30 days showed that all treatments significantly reduced pigmentation and biomass. Physiological assays indicated declines in chlorophyll a, chlorophyll b, carotenoids and catalase activity. Microbial community analysis revealed that, while total bacterial/fungal abundance remained unchanged, alpha diversity and composition were affected, especially by CC. Key cyanobacteria like Leptolyngbya and Scytonema were strongly suppressed. CC showed the strongest inhibition but broader ecological impact, whereas MC offered moderate suppression with minimal disturbance. Plant distillates are thus effective, eco-friendly alternatives to synthetic biocides, providing a sustainable strategy for cave conservation amid tourism.