Pressures from long term environmental change at the shrines and temples of Nikkō

Abstract

Background: Important historic buildings at Nikkō are designated National Treasures of Japan or important cultural properties and illustrate notable architectural styles. We examine the records of damaging events and environmental change to estimate that changing balance of threats to guiding strategic planning and protection of the buildings and associated intangible heritage. Methods: Historic records from Nikkō allow past damage to be assessed along with projections of likely future threats. Simple non parametric statistics, Lorenz curves and its associated Gini coefficient aids interpretation of observations. Results: Earthquakes have long represented a threat, but mostly to fixed stone structures. Flooding may be as growing problem, but historically river management has improved. Increasing warmth may mean an increase in the threat of fungal attack. However, insect attack on wood has been a particular problem as recent years have seen damage by wood boring insects, particularly at Sanbutsudō in the temple complex of Rinnō-ji. Although warmer climates may enhance the abundance of insects such as P. cylindricum the life cycle of this rare anobiid is not well understood. The risk of forest fires tends to be higher in drought period, but summer rainfall may well increase at Nikkō. Additionally good forestry practice can reduce this risk. Future changes to climate are likely to alter the flowering dates and the arrival of autumn colours. Conclusion: The results show that environmental changes are likely to affect the material structure and also the nature of celebrations and visitor frequency at Nikkō. Conservation architects and skilled engineers will be challenged by these changes, so need to be well briefed on strategic environmental threats.