Brimblecombe and Hayashi Herit Sci (2018) 6:27 https://doi.org/10.1186/s40494-018-0186-1 RESEARCH ARTICLE Open Access Pressures from long term environmental change at the shrines and temples of Nikkō Peter Brimblecombe1* and Mikiko Hayashi1,2 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 coefcient aids interpretation of observations. Results: Earthquakes have long represented a threat, but mostly to fxed stone structures. Flooding may be as grow- ing 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 fres 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 fowering dates and the arrival of autumn colours. Conclusion: The results show that environmental changes are likely to afect 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. Keywords: Climate change, Flooding, Fire, Fungi, Earthquakes, Insects, Landscape change, Wooden buildings Introduction the 8th century. Tey are distributed among the various Tere are more than a hundred important historic build- temple complexes discussed in the text, along with a sat- ings at Nikkō. Tese are designated National Treasures ellite set of buildings associated with Rinnō-ji situated ff- of Japan or important cultural properties. Tis site is teen kilometres away at Tyuzen-ji. Te key sites, Rinnō-ji, important because it illustrates the architectural style Tōshō-gū and Futarasan Shrine form the Shrines and of the Edo period as applied to Shinto shrines and Bud- Temples of Nikkō that represent important elements of dhist temples. Tese are arranged on forested moun- UNESCO World Heritage. Te temple complex and its tain slopes so as to create striking visual efects making surroundings have long been a destination for travelers. the setting signifcant in addition to the importance the Te poets Sōgi [1] and Matsuo Basho made visits in 1468 historic buildings. Although many of the buildings were and 1689 respectively and Nikkō features in Basho’s most constructed in the 17th century, the earliest date from famous work, Te Narrow Road to the Deep North. West- ern tourism started early also with a notable visit from *Correspondence: [email protected] the crew of the Challenger in 1875 [2] and early travel 1 School of Energy and Environment, City University of Hong Kong, Tat writers [e.g. 3]. Many important Japanese painters have Chee Avenue, Kowloon, Hong Kong SAR found inspiration in Nikkō and its surroundings, notably Full list of author information is available at the end of the article © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Brimblecombe and Hayashi Herit Sci (2018) 6:27 Page 2 of 12 the 20th-century painter and printmaker Hiroshi Yoshida shifting balance of threat in the future as a way of guid- [4]. In the 21st century annual reports reveal that there ing long term strategic planning and risk assessment at are typically some six million visitors to Nikkō each year, Nikkō. but they go there as much to enjoy the natural environ- ment as the temples, with autumn popular to observe the Method leaves. Tis work uses historic records from Nikkō to assess past Heritage always faces a range of threats and Nikkō has damage along with the magnitude of various climate and been vulnerable to earthquake, foods, lightning strikes, environmental threats. Te layout of the site is shown by fre and most recently insect attack. In future these the map in Fig. 1b, which marks the key religious com- threats may be exacerbated by environmental and climate plexes of the site along with individual monuments and change. Te aim here is to examine the records of dam- buildings discussed in the text. Where possible we have aging events and environmental change to estimate that used climate projections available from the Japanese Fig. 1 Maps: a the climate types of Japan as adopted by the Japanese Meteorological Agency, which defnes seven regions (i) the Sea of Japan side of northern Japan (NJJ), (ii) the Pacifc side of northern Japan (NJP), (iii) the Sea of Japan side of eastern Japan (EJJ), (iv) the Pacifc side of eastern Japan (EJP), (v) the Sea of Japan side of western Japan (WJJ), (vi) the Pacifc side of western Japan (WJP), and (vii) Okinawa/Amami (OKI) and b the site of the Shrines and Temples of Nikkō marking locations discussed in the text. The larger lettering defnes the major religious sites, while smaller lettering denotes individual buildings and monuments that are discussed in the text, with green areas denoting sites with shrines and orange with buildings belonging to Rinnō-ji Brimblecombe and Hayashi Herit Sci (2018) 6:27 Page 3 of 12 Meteorological Agency to estimate likely future threat Earthquakes from changed weather. Te Japanese climate is generally Earthquakes have long represented a threat to buildings temperate, though it ranges from the subarctic zone of in Japan and their design even in historic times attempted the most northerly island of Japan, Hokkaido, where the to resist the shocks. Te record of signifcant earthquakes average annual temperature is 6–10 °C to the subtropical starts with accounts of events as early as the 5th cen- zone of the southern island, Okinawa and is divided into tury [7] and at Nikkō damage was noted from the Edo or regions as shown in Fig. 1a. We have used simple statis- Tokugawa period (1603–1868), but the accounts seem to tical tests to explore the data gathered. Te Kendall tau list only minor damage (Table 1). test used Wessa-net (https://wessa.net/) for non para- Tere was a large earthquake in 1683 and possibly metric correlation analysis, while the Sen slope (median some smaller shocks. Te damage caused was costly and slope) was determined using the Teil-Sen calculator at led to disagreements between Lord Date Tsunamura Single Case Research (http://www.singlecaseresearch. (1659–1719), who wanted a minimalist restoration and org/calculators/theil-sen). Additionally Lorenz curves the Tokugawa Shogunate who wished for a fuller resto- and the associated Gini coefcient were used to describe ration. Te dispute occurred as the famous poet Matsuo the insect catch as the distribution is highly dispersed Basho and his travelling companion Kawai Sora, were [5]. Te Gini coefcient and its standard error were cal- to depart on a journey through Nikkō early in 1689 [8]. culated from the number of trapped insects using the Te government hoped that Matsuo Basho could pro- method suggested by Owang [6]. vide information about the restoration. However, Basho Results and discussion have been split into a number of wrote relatively little of Nikkō in Te Narrow Road to the sections for clarity: past impacts on the site, earthquakes, Deep North, although this prose-poem ofers clues and climate and climate change at Nikkō, foods and storms, suggests that his thoughts would not be public ones: “To fungal damage at Nikkō, insect damage at Nikkō, fres say more of the shrine would be to violate its holiness [9]”. at Nikkō and landscape change and seasons at Nikkō. A minimalist restoration seems to have prevailed and Te recent discovery of insect damage at Nikkō, makes reminds that in the past, as with today, there were ten- the section on insects rather long, so it is been split to sions over funding and extent of restoration. include introductory material and other subsections. Te traditional wooden buildings of Japan are resistant to earthquakes as they respond to earth movements. Te Past impacts on the site fve-story pagoda characteristic of Japanese architecture Te historic site of Nikkō has often experienced seri- consists of foors with beams only weakly linked, but held ous damage in the past from extreme events. Te occur- in vertical alignment by a central pole. Each foor is efec- rence of such events can give us a sense of past threats, tively an independent structure of decreasing dimension although we have to remember there are more subtle with height. Wide heavy eaves stabilize the building as the long-term threats, which lead to cumulative, rather than inertia reduces the degree to which the building sways. catastrophic damage, have probably gone unrecorded Wooden Japanese buildings have the ability to recover in the past.