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Bio-Heritage

Kew represents the intersection of biodiversity conservation and World Heritage protection, where the overlap of these two fields creates a unique environment for deep, innovative, and interdisciplinary research to flourish.

Life on Heritage: The Subtle Art of Lichen–Stone Interaction

Historic Surface Interactions

Historic surfaces at Kew provide a rare, real-world framework for examining how lichens interact with diverse materials under long-term, low-intervention management. These interactions span both biodeteriorative and bioprotective processes, offering critical insights for heritage conservation.

Granite
Lichens exploit microfractures and feldspar-rich zones, contributing to mineral weathering through organic acids while also stabilising surfaces by reducing moisture fluctuation.
Sandstone
High porosity supports endolithic and epilithic lichen communities. Hyphal penetration and salt–microbe interactions can accelerate granular disintegration, making sandstone ideal for studying microenvironment-driven decay.
Travertine
Calcium-rich and highly reactive, travertine hosts calcicolous lichens whose metabolic activity influences carbonate dissolution, recrystallisation, and surface micromorphology.
Limestone
Lichen–limestone interactions reveal the dual role of lichens as agents of biocorrosion and surface stabilisation, particularly through oxalate formation and endolithic growth.
Bricks
Brick substrates support complex biofilms where lichens interact with bacteria and fungi, driving salt mobilisation, pore expansion, and heterogeneous deterioration patterns.
Iron and metal elements
Lichens colonising iron surfaces influence corrosion dynamics by trapping moisture, altering redox conditions, and creating localized microclimates at the metal–air interface.

Together, these historic surfaces demonstrate how material composition, porosity, and microclimate shape lichen community structure and function. Kew thus represents a unique convergence of biodiversity conservation and World Heritage protection, where observing lichen–material interactions in situ enables interdisciplinary research linking ecology, geomicrobiology, and heritage science.

Potential Research

Lichen Diversity on Historic Materials
Surveying lichens on stone, brick, mortar, terracotta, and concrete across Kew’s historic structures.
Material-Specific Colonisation Patterns
Comparing lichen communities on different building materials and construction periods.
Bioreceptivity of Historic Surfaces
Assessing physical and chemical properties that influence lichen establishment.
Growth Dynamics and Longevity
Measuring growth rates, persistence, and succession of lichens on heritage surfaces.
Biodeterioration vs Bio-Protection
Evaluating when lichens contribute to surface decay and when they offer protective functions.
Microclimate and Surface Ecology
Linking moisture, exposure, orientation, and shading to lichen distribution.
Climate Change Impacts
Investigating how warming, altered rainfall, and extreme events affect lichens on historic structures.
Non-Invasive Monitoring Techniques
Applying imaging, spectroscopy, and digital surface mapping to track changes without damage.
Cleaning and Management Effects
Studying lichen recolonisation following conservation or cleaning interventions.
DNA-Based Identification and Cryptic Diversity
Using molecular tools to resolve species complexes on heritage substrates.
Indicator Species for Heritage Health
Identifying lichens that signal environmental stress or surface vulnerability.
Decision-Support for Conservation Practice
Translating ecological data into guidance for heritage managers.

Beside the pool, several aged stone urns stand together, their surfaces gradually covered by lichens. Pale green and silvery-grey patches follow the contours of each urn, sustained by constant moisture and reflected light, turning these vessels into living markers of time and the interaction between stone, water, and biodiversity.

Inscriptions

Stone inscriptions in areas such as Rock Garden are vulnerable to lichen colonisation due to surface roughness, moisture retention, and limited disturbance. Lichens can obscure carved details and, over time, contribute to chemical and physical alteration, posing challenges for the legibility and long-term conservation of inscribed historic surfaces.

Temples

Historic temples at Kew are particularly susceptible to lichen colonisation due to their stone surfaces, age, and exposure to moisture and shade. Bird perching further enriches these structures with nitrogen, favouring nitrophilous lichens and enhancing biological growth on culturally significant architectural elements.

Statues

Statues at Kew are exposed to lichen colonisation for multiple reasons. Birds frequently perch on these structures, enriching surfaces with nitrogen through droppings, which promotes the growth of nitrophilous lichens and accelerates biological colonisation of historic materials.

Lichens are among the earliest colonisers of stone surfaces, and while they enrich the visual character of heritage landscapes, their long-term interaction with historic materials can contribute to biodeterioration. As they anchor themselves to stone monuments and old brickwork, lichen thalli and their penetrating rhizines can exploit microscopic pores and weaknesses. Over time, biochemical processes—such as the production of organic acids—may enhance surface weathering, leading to granular disintegration, pigment alteration, or the gradual loss of carved details. Understanding these subtle yet persistent effects is essential for balancing conservation needs with the ecological value lichens bring to cultural heritage environments.

Kew Gardens contains numerous cultural heritage structures—including historic stonework, commemorative monuments, Victorian architecture, and iconic garden features—that provide valuable substrates for lichen colonization. Lichens frequently establish on these surfaces because stone offers long-lived, chemically stable microhabitats that support slow-growing crustose and foliose species. While lichen growth contributes to biodiversity and can provide protective microfilms against weathering, it can also present conservation challenges. Some species promote mechanical and chemical deterioration through hyphal penetration, acid secretion, or moisture retention, accelerating granular disintegration or salt mobilization in vulnerable stones. Decisions about lichen removal therefore require a nuanced, site-specific balance between heritage preservation and ecological value. Mechanical or chemical cleaning techniques may risk damaging fragile masonry, altering surface porosity, or disrupting patina layers. As a result, heritage managers at Kew face the dual challenge of conserving historic stone structures while acknowledging lichens as integral components of the Garden’s ecological heritage. Sustainable preservation strategies increasingly favour minimal intervention, selective removal only when structural risk is evident, and the use of non-invasive monitoring tools to evaluate biodeterioration processes over time.

Old Bricks

New Bricks

On newly installed bricks at the Jodrell Laboratory, lichens readily establish, particularly in areas where sufficient moisture and light are available. These early colonisation patterns provide valuable insight into the initial stages of lichen growth and bioheritage processes on modern building materials.

Stone Pavements

Various stone pavements at Kew, although lacking inscriptions or decorative features, represent distinct phases of the garden’s architectural history. These surfaces host diverse lichen communities, reflecting long-term environmental exposure and illustrating subtle interactions between living biodiversity and historic built fabric within the garden.

Palaces

Palm House

Treetop Walkway

Great Pagoda

Walls

Rock Garden

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