The elevational changes in vegetation are related to the changes in environmental factors, such as temperature. Evergreen conifers Abies veitchii and A. mariesii dominate the subalpine zone between 1600 and 2000 m and between 2000 and 2500 m above sea level (a.s.l.), respectively, in central Japan. This study examined why their dominating elevations are separated by investigating the temperature–photosynthesis relationship at high and low elevations (1600 m and 2300 m a.s.l.). This study tested two hypotheses: (1) the optimal temperature (T_opt) for the maximum photosynthetic rate (P_max) is lower in individuals grown at high elevation than at low elevation, and A. mariesii has lower T_opt than A. veitchii at each elevation; and (2) P_max of individuals grown at low elevation is greater in A. veitchii than in A. mariesii, while that of individuals grown at high elevation is greater in A. mariesii than in A. veitchii. Saplings of the two conifers were sampled at high and low elevations. The photosynthetic rate was measured at the laboratory. Contrary to the hypotheses, both species had the same T_opt at two elevations, and P_max was greater in A. veitchii than in A. mariesii, irrespective of the elevation where the individuals grew. The elevational distribution of the two species could not be explained by the temperature–photosynthesis relationship. Therefore, factors other than the temperature–photosynthesis relationship are important to understand the elevational separation of the two species.

植被的海拔变化与温度等环境因素的变化有关。常绿针叶树Abies veitchii和A. mariesii分别在日本中部海拔 1600 至 2000 米和海拔 2000 至 2500 米（asl）之间的亚高山地带占主导地位。本研究通过调查高海拔和低海拔（1600 m 和 2300 m asl）的温度 - 光合作用关系来研究为什么它们的主要海拔是分开的。本研究验证了两个假设：（1）在高海拔生长的个体中，最大光合速率（P _{max ）的最佳温度（} T _opt ）低于在低海拔生长的个体，并且A. mariesii具有较低的T _opt比A. veitchii在每个海拔; (2) A. veitchii低海拔个体的P _max大于A. mariesii，而高海拔个体的 P max 则A. mariesii大于A. veitchii。在高海拔和低海拔地区对两种针叶树的树苗进行取样。光合速率是在实验室测量的。与假设相反，两个物种在两个海拔高度具有相同的T _{opt ，并且}A. veitchii的P _max大于A. mariesii，与个体生长的海拔高度无关。这两个物种的海拔分布不能用温度-光合作用关系来解释。因此，温度-光合作用关系以外的因素对于理解这两个物种的海拔分离很重要。