Lichens of the Iranian Cultural World Heritage Sites

Lichens, as symbiotic organisms composed of fungi and photosynthetic partners, play a multifaceted role in the conservation ecology of Iran’s cultural UNESCO World Heritage Sites. These sites—such as Persepolis, Pasargadae, Bam Citadel, Takht-e Soleyman, and Soltaniyeh—are not only of outstanding historical and architectural value but also function as long-standing natural laboratories for studying biocolonization and stone weathering processes under arid and semi-arid climatic conditions.

Ecologically, lichens are among the earliest colonizers of exposed stone surfaces. Their biological activity contributes to both biodeterioration and bioprotection of historic substrates. On one hand, epilithic and endolithic lichens may chemically alter stone through the production of organic acids (e.g., oxalic acid), leading to micro-pitting, mineral leaching, and progressive disintegration of building materials. On the other hand, certain crustose lichen species form a stable biological patina that can reduce water infiltration, buffer temperature fluctuations, and limit colonization by more aggressive microbial or plant taxa. This duality highlights the necessity for site-specific and species-level understanding in conservation strategies.

From a conservation science perspective, lichens serve as bioindicators of environmental conditions at heritage sites. Their sensitivity to pollution, microclimatic variation, and human-induced disturbances makes them valuable tools for monitoring changes in site stability and atmospheric quality—particularly in urban-proximate locations like Golestan Palace or Meidan Emam of Isfahan. Lichen diversity and community structure can thus inform early-warning systems and preventive conservation measures.

Additionally, lichens on cultural monuments represent archival biodiversity, potentially harboring cryptic or endemic taxa adapted to anthropogenic stone habitats over centuries. These species contribute to the biocultural heritage of the sites, linking ecological resilience with cultural continuity. Incorporating lichenological studies into heritage management not only enhances our understanding of biodeterioration dynamics but also supports integrated conservation models that balance material preservation with ecological stewardship.

Despite their significance, lichens remain largely understudied in Iranian heritage conservation frameworks. Targeted lichen surveys, molecular identification, and long-term monitoring are urgently needed to assess species diversity, biodeterioration potential, and conservation status. Developing an interdisciplinary approach—linking mycology, lichenology, restoration science, and heritage management—will advance both the preservation of Iran’s iconic monuments and the protection of associated micro-ecosystems.