Air pollution is one of the most pressing environmental challenges of the 21st century, affecting ecosystems, human health, and cultural heritage. While instrumental monitoring provides valuable quantitative data, it often lacks spatial and biological context. Lichens, however, bridge this gap — acting as living recorders of atmospheric quality. As complex symbiotic organisms formed by fungi and photosynthetic partners (algae or cyanobacteria), lichens have no protective cuticle or roots, absorbing water and nutrients directly from the air. This unique physiology makes them highly sensitive to airborne pollutants and therefore excellent bioindicators of environmental change.

Lichens respond to pollutants in measurable ways — including changes in species richness, physiological damage, pigment alteration, and bioaccumulation of contaminants such as sulfur dioxide (SO₂), nitrogen oxides (NOₓ), ozone (O₃), and heavy metals (Pb, Zn, Cu, Cd). By analyzing lichen communities and their chemical composition, researchers can assess air quality over broad areas and over long periods, even where monitoring stations are absent.

Lichens as Silent Witnesses of Atmospheric Change in Iran

Iran’s vast geographical extent and striking environmental heterogeneity — ranging from humid Hyrcanian forests and Zagros mountains to central arid deserts and southern coastal zones — provide an exceptional natural laboratory for lichen biomonitoring. Each region offers distinct climatic and industrial pressures that influence lichen diversity and pollutant exposure. For example, industrial and urban centers such as Tehran, Esfahan, and Tabriz face elevated levels of sulfur and nitrogen pollution, leading to reduced lichen diversity and the dominance of tolerant species. In contrast, pristine habitats in the Alborz highlands or Caspian forests still harbor diverse, pollution-sensitive taxa that can serve as reference sites for ecological comparison.

Despite this potential, lichen biomonitoring in Iran remains underdeveloped compared to many European countries. Most Iranian lichen research to date has focused on taxonomy and distribution, while their role in pollution monitoring and ecophysiological response has been less explored. Yet, the country’s combination of ancient cultural landscapes, growing industrial regions, and diverse ecosystems makes it particularly urgent and valuable to expand this field.

Our Research Vision at MYCOLICH

At MYCOLICH, we aim to advance the field of lichen-based biomonitoring in Iran through integrative and multidisciplinary research. Our ongoing projects focus on:

• Mapping the spatial distribution of epiphytic and saxicolous lichens across urban–rural gradients

• Measuring trace metal accumulation and isotopic signatures using advanced analytical techniques such as ICP–MS 

• Evaluating physiological stress responses through chlorophyll fluorescence, photosynthetic pigments, and metabolomic profiling

• Developing a national reference database of sensitive and tolerant indicator species linked to specific pollutants

These efforts not only provide ecological insights but also contribute to evidence-based environmental policy, offering a biological complement to instrumental air-quality data.

Cultural and Environmental Relevance

Iran’s cultural heritage sites — from stone monuments to ancient brick structures — are also at risk from air pollutants that interact with biological colonizers such as lichens, algae, and fungi. Understanding how airborne contaminants influence the growth and composition of lichen communities on these monuments can inform both biodeterioration control and heritage conservation. Thus, lichen biomonitoring stands at the intersection of environmental protection and cultural preservation.

Moreover, the study of Iranian lichens as bioindicators has global importance. It helps to fill a geographic knowledge gap in Southwest Asia, allowing international comparisons of pollution patterns and the effects of climate change on lichen biodiversity. By training young researchers and collaborating with universities, environmental agencies, and conservation institutions, MYCOLICH seeks to build national capacity in this emerging field.

Looking Forward

Our goal is to establish a long-term Lichen Biomonitoring Network for Iran, integrating ecological, chemical, and geospatial data into an accessible digital platform. Through this initiative, we aim to raise awareness of the ecological value of lichens and their vital role as sentinels of atmospheric health.

Lichens remind us that even the smallest organisms can speak volumes about the health of our planet. Protecting them — and learning from their signals — is essential not only for environmental management but also for ensuring a sustainable future for Iran’s ecosystems and communities.