Influence of air pollution on the mountain forests along the Tateyama–Kurobe Alpine route

Abstract

The effects of air pollution on the growth of mountain trees were investigated at Buna-daira (1,180 m a.s.l.), about half the way up Mt. Tateyama, located in Japan. Every year, about 1 million tourists are transported by highland buses through the Tateyama-Kurobe Alpine route. Since the route opened in 1971, some tree species along the road have declined and have been blighted, suggesting that bus exhaust was the cause. However, the level of regional and long-range transboundary air pollution has also increased significantly over the last few decades. The atmospheric NO 2 concentration at the roadside in the forest was highly correlated with the traffic density of buses and penetration of the exhaust into the forest was detected. However, the maximum average NO 2 concentration was lower than 3.5 ppbv during the peak traffic period in the year. At Bunadaira, the total stem cross-sectional area at breast height (BA) of the forest was nearly unchanged from 1999 to 2006, but the BA of Fagus crenata decreased 10% and that of Cryptomeria japonica increased 6%. Neither tree growth nor tree death was significantly correlated with distance from the road. The cause of the decline of F. crenata could not be attributed to the effects of road, i.e., air pollution emitted from the buses or edge effects of the road. This area was more affected by regional, longrange transport of air pollution (O 3 , SO 2 , etc.). The average atmospheric O 3 concentration in autumn was higher than 40 ppbv and the recent increase in the O 3 concentration may be an important factor of F. crenata decline through the changes in the interspecific relationships between F. crenata and C. japonica, O 3 sensitive and tolerant species, respectively.

Experimental Studies on the Effects of Ozone on Growth and Photosynthetic Activity of Japanese Forest Tree Species

“…Recently, Takeda and Aihara (2007) showed that O 3 negatively affects growth and photosynthetic parameters of Japanese beech grown under field condition at Tanzawa Mountains where the decline of Japanese beech forest has been reported. Kume et al (2009) suggested the possibility that recent increase in the atmospheric concentration of O 3 is an important factor of Japanese beech decline at Mt. Tateyama based on the results of their field survey.…”

“…In Japan, relatively high concentrations of O 3 above 100 nL L -1 (ppb) have been frequently observed from spring to autumn in several mountainous areas Takeda and Aihara, 2007;Aihara et al, 2004;Maruta et al, 1999). Based on the results of the experimental studies and field surveys, it has been suggested that O 3 is an important environmental stress relating to the forest decline in Japan (Kume et al, 2009;Suto et al, 2008;Takeda and Aihara, 2007;Yamaguchi et al, 2007b;Kohno et al, 2005;Aihara et al, 2004;Yonekura et al, 2001a, b;Maruta et al, 1999).…”

Historical changes in soil acidification inferred from the dendrochemistry of a Tateyama cedar at Bijodaira, Mt. Tateyama, Japan

“…Recent studies show that the areas along the Japan Sea coast in central Japan have been exposed to larger amounts of atmospheric pollut-concentrations at Bijodaira in 2006 with those in 1992 and found that the concentrations (<~3 ppbv) in 1992 and 2006 along the Alpine route were lower than the critical level (8 ppbv) known to cause physiological changes under field conditions. Based on these data, they concluded that the cause of the decline of F. crenata might not be the local air pollution attributed to public highland buses, but that other stress effects such as regional and longrange transport of air pollutants may have caused the tree decline phenomenon (Kume et al, 2009).…”

Estimation of ozone concentrations above forests using atmospheric observations at urban air pollution monitoring stations

“…Conversely, mountainous areas at high altitude show less distinct diurnal changes since nocturnal O 3 depletion is not prominent (Wolff et al, 1987), due to lower NO emission (Kume et al, 2009;Yamada et al, 2012;Wada et al, 2014). Furthermore, as titration processes are less frequent over forests than urban areas, higher daytime O 3 concentrations might be observed in rural areas (Gregg et al, 2003).…”