Takahashi Koichi, Ikeda Keigo, Okuhara Isao, Kurasawa Rintaro, Kobayashi Suguru
Department of Biology Faculty of Science Shinshu University Matsumoto Japan.
Institute of Mountain Science Shinshu University Matsumoto Japan.
Ecol Evol. 2022 Feb 19;12(2):e8647. doi: 10.1002/ece3.8647. eCollection 2022 Feb.
Climatic change will affect elevational vegetation distribution because vegetation distribution is related to thermal conditions. However, how elevational species distributions are determined by biotic and abiotic factors is not clear. The long-term plot census along an elevational gradient is indispensable to clarify mechanisms of elevational distribution of tree species. Two congeneric conifers, the less shade-tolerant and shade-tolerant . , dominate at low and high elevations, respectively, in the subalpine zone in Japan. This study investigated the population dynamics of the two species at three elevations (low, middle, high) for 13 years to examine why the two species dominated the different elevations from the viewpoints of competition and disturbance. This study showed that growth and survival rates were not highest at the most dominant elevations for each species. At the high elevation where . dominated and small disturbances frequently occurred, the recruitment rate of . was highest among the three elevations and that of . was largely decreased by tree competition. However, . was dominant earlier than . at the low elevation after large disturbances by the high growth rate of individual trees. Therefore, . was superior to . at the high elevation because of its high recruitment rate and large reduction of recruitment of . due to competition, while . was superior to . at the low elevation after large disturbances because of higher growth rate than . . It is suggested that the elevational distributions of the two species were determined by elevational changes in population dynamics in relation to competition and disturbance. Long-term observational studies of forest dynamics among various elevations are indispensable to predict the effects of climatic change on vegetation distribution.
气候变化将影响植被的海拔分布，因为植被分布与热条件相关。然而，生物和非生物因素如何决定物种的海拔分布尚不清楚。沿海拔梯度进行长期的样地普查对于阐明树种海拔分布的机制是必不可少的。在日本亚高山带，两种同属针叶树，耐荫性较差的 和耐荫性较强的 ，分别在低海拔和高海拔地区占主导地位。本研究调查了这两个物种在三个海拔高度（低、中、高）13年的种群动态，从竞争和干扰的角度探讨这两个物种为何在不同海拔高度占主导地位。本研究表明，每个物种的生长率和存活率在其最占优势的海拔高度并非最高。在 占主导且小干扰频繁发生的高海拔地区， 在三个海拔高度中的更新率最高，而 的更新率因树木竞争而大幅下降。然而，在经历大干扰后，由于个体树木的高生长率， 在低海拔地区比 更早占主导地位。因此， 在高海拔地区由于其高更新率和因竞争导致的 的更新率大幅下降而优于 ，而 在大干扰后的低海拔地区由于其生长率高于 而优于 。这表明这两个物种的海拔分布是由与竞争和干扰相关的种群动态的海拔变化决定的。对不同海拔高度森林动态进行长期观测研究对于预测气候变化对植被分布的影响是必不可少的。
