Situations and cause of red coloration of Pinus thunbergii crown occurred in 2013 spring at the coastal region of Iburi and Hidaka, Hokkaido

Abstract

In 2013 spring, red coloration of Pinus thunbergii crown was widely observed at the coastal region of Iburi and Hidaka, Hokkaido. We surveyed the distribution of the red colored trees and stands along the coast, and found that it aggregated at S-SW faced regions. High mortality in the severely damaged trees (red part of crown was ≥ 91%) was observed for consecutive two years. Since the greatest maximum wind speed was recorded at several meteorological observatories, wind storm with little rain at 6-7 December 2012 was suspected to be cause of red coloration of P. thunbergii crown. Furthermore, cumulative wind speed of sea breeze was significantly correlated with severity of crown damage in regional scale. These supporting evidences lead us to consider that the red coloration of P. thunbergii crown was caused by seawater.