Effects of climate on the radial growth of tree species in the upper and lower distribution limits of an altitudinal ecotone on Mount Norikura, central Japan

Abstract

This manuscript consists of 21-typed pages including figure legends, 1 table and 3 figures. Takahashi et al. 2 To show what climatic conditions affect the growth of tree species in the upper and lower distribution limits of an altitudinal ecotone, tree-ring width chronologies were developed for Abies veitchii, Betula ermanii and Betula platyphylla var. japonica in their altitudinal ecotone (about 1600 m above sea level) on Mt. Norikura, central Japan.This altitude was the lower distribution limit for A. veitchii and B. ermanii in the subalpine zone, and was the upper distribution limit for B. platyphylla var. japonica in the montane zone on Mt. Norikura. The tree-ring widths of the two Betula species and A. veitchii were positively correlated with the August precipitation of the current year and that of the previous year, respectively. Precipitation in the hottest month of August was less compared with other months during summer. The tree-ring width of B. platyphylla var. japonica showed no correlation with temperatures of any month in its upper distribution limit. In contrast, the tree-ring widths of B. ermanii and A. veitchii were negatively correlated with the August temperatures of the current year and of the previous year, respectively, in the lower distribution limit of these species. Therefore, the two Betula species and A. veitchii responded to climatic conditions of the current year and those of the previous year, respectively. This study also suggests that water deficit in August reduces the growth of the three species in this altitudinal ecotone, irrespective of the upper or lower distribution limit, and that a high August temperature is more detrimental to the growth of A. veitchii and B. ermanii in their lower distribution limit. Thus, the examined three species with different altitudinal distributions differently responded to climatic conditions in this altitudinal ecotone on Mt. Norikura.

Climatic factors affecting the tree‐ring width of Betula ermanii at the timberline on Mount Norikura, central Japan

“…It is considered that the growth of B. ermanii strongly depends on the current-year's photosynthetic production (Kikuzawa 1983). Therefore, the growth of B. ermanii is apt to be affected by the current-year's climatic conditions (Takahashi et al 2003). Accordingly, it is no doubt that less insolation duration and low temperature due to frequent rain events in summer of the current year reduce the tree-ring width of B. ermanii at the timberline.…”

“…We also compared the results of this study with those of our previous study (Takahashi et al 2003), conducted in the lower altitudinal limit of B. ermanii on Mount Norikura.…”

“…This slope was the same slope that our low altitudinal study site (1600 m a.s.l.) was located (Takahashi et al 2003). The horizontal distance between the two study sites was 4.5 km.…”

“…Therefore, B. ermanii is one of representative tree species at the timberlines in Japan. Takahashi et al (2003) examined the effects of climatic conditions on the tree-ring width of B. ermanii in its lower altitudinal limit on Mount Norikura in central Japan. They suggested that less precipitation combined with high temperature in the hottest month of August reduced the tree-ring width of B. ermanii.…”

“…The available meteorological data at Matsumoto began in 1898 for temperature and precipitation, and in 1899 for insolation duration. The correlations of climatic data between the two stations were highly significant (Takahashi et al 2003). Thus, we used the long-term climatic data recorded at Matsumoto.…”