title: Accelerated stone deterioration induced by forest clearance around the Angkor temples.
abstract: The present study provides the first quantitative assessment of the deteriorative impact of forest clearance on susceptible sandstone masonries. At Ta Keo, a 1000yr-old temple cleared of the Angkor forest in the early 20th century, GIS-based analysis of historic imagery indicates an average ten-fold increase in stone loss rates (0.2 instead of 0.02% per year). This accelerated decay is assigned to the climatic stress provoked by the exposure of fragile ornamented sandstones to the harsh impact of tropical sunshine and monsoon rains. Comparative climate monitoring with the Beng Mealea temple, still located in a forested environment, suggests a three-fold post-clearance increase in daily temperature and humidity ranges, which is conducive to enhanced swelling-shrinking movements responsible for accelerated sandstone contour scaling. Comparative visual assessment based on a customised 7-point scale of mechanical weathering confirms the protective role of canopy, with 79% of decorative motifs still almost free of mechanical weathering in the forest (against 7% at the cleared site). Disruption of archaeological structures by roots of individual trees can be locally observed at Angkor, but this does not negate the dominant overall buffering function of the forest cover. At Angkor and other cultural heritage sites, this bioprotective 'umbrella effect' should be considered as a valuable ecosystem service to be taken into account when defining and implementing strategies of sustainable management.
authors.affiliation: Clermont Université, Université Blaise Pascal, GEOLAB, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6042, GEOLAB, F-63057 Clermont-Ferrand, France; Institut Universitaire de France, Paris, France. Electronic address: m-francoise.andre@univ-bpclermont.fr.
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: André
authors.affiliation: Clermont Université, Université Blaise Pascal, Maison des Sciences de l'Homme, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, USR 3550, MSH, F-63057 Clermont-Ferrand, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Vautier
authors.affiliation: Clermont Université, Université Blaise Pascal, GEOLAB, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6042, GEOLAB, F-63057 Clermont-Ferrand, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Voldoire
authors.affiliation: Clermont Université, Université Blaise Pascal, GEOLAB, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6042, GEOLAB, F-63057 Clermont-Ferrand, France.
authors.forename: Erwan
authors.initials: E
authors.lastname: Roussel
keywords: Angkor World Heritage Site; Bioprotection; Forest clearance; Human-induced climate stress; Stone decay