Message - 7th IAL Symposium

3B-2-O
Lichen: from genome to ecosystem in a changing world
3B-2: The ecological roles of lichens in diverse ecosystems
(3B-2 - O1) Submission ID: IAL0119-00001
ROLE OF LICHENS IN DETERIORATIVE PROCESSES THREATENING OUR STONY
CULTURAL HERITAGE: CASE STUDY OF LICHEN COLONIZATION
IN MACHU PICCHU (PERU)
De Los Rios A. 1 , Perez-Ortega S. 1 , Speranza M. 1 , Huallparimachi G. 2 , Wierzchos J. 1 ,
Galvan V. 3 , Astete F. 2 , Ascaso C. 1
1 Biologia Ambiental, MNCN-CSIC, Madrid, Spain
2 Seccion Cuzco, Ministerio Cultura Peru, Cuzco, Peru
3 IE Universidad, Segovia, Spain
Machu Picchu is the icon of the Inca World due to its extraordinary emplacement in which the architecture
harmonizes completely with its amazing natural scenic surroundings. The conservation of this sanctuary is
an important task for humanity in order to preserve our cultural heritage. One important risk for its conservation
is the detrimental effect of the biological colonization of its walls. This colonization is enhanced by Machu Picchu’s
natural emplacement in a tropical climate. Lichens are the main colonizers of its walls. Together with bryophytes,
they completely cover the stone in untreated areas and are present also in areas previously treated for
eliminating biological colonization. Crustose forms are the most frequently observed lichens in the emblematic
constructions because Machu Picchu’s caretakers mechanically remove the foliose and fructicose forms. The
external effects of lichen colonization can be appreciated by simple observation, but the associated biodeterioration
processes are complex, since lichen growth is usually not restricted to external zones and their effects are
added to these generated by the activity of microorganisms present nearby. Hence, we have characterized the
interphase lichen-lithic substrate by electron microscopy in monument samples colonized by different species in
order to evaluate the differential deteriorative capacity of each one. In general, crustose species were the most
important deteriorative agents due to the close interactions established between mycobiont cells and the lithic
substrate. Signs of mechanical alterations can be clearly associated to their presence. Disaggregation of stone
surface and detachment and separation of mica layers are phenomena frequently observed. The detereriorative
lichen activity was conditioned by the physiochemical properties of the stone and the presence of endolithic
microorganisms. It has been shown that there is a harmful action of lichens on Macchu Picchu stone but their
elimination might not always be the best strategy for preserving this monument. Only a temporary aesthetic
improvement is obtained with the previous treatments because the stone is quickly recolonized. New treatments
based in combination of biocide and laser cleaning are being assayed on Machu Picchu’s quarry rock in order to
design the best strategy to preserve this wonder world.
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