Formation Mechanisms of Community Boundaries in Subalpine Coniferous Forests

以日本北海道亚高山森林为研究对象，对边界分明的林分类型马赛克景观的形成与动态进行了研究。主要研究地点位于北海道东部七子半岛的安内别山西坡。本文描述了青杉纯林分与冷杉、青杉、白桦混交林组成的马赛克景观。对两种林分类型的林分核心和林分边缘的详细普查表明，林分边界的不连续与沿林分边界逐渐变化的土壤条件无关。边界周围的动态序列从云杉纯林分到混交林分。这一替换过程可能与不同物种对冠上积雪和风的耐受性差异有关。调查的另一个地点是北海道南部Komagatake山斜坡上的演替景观。利用连续航拍资料分析了落叶松入侵的动态格局。作为一种通用的建模工具，本研究提出了一种新的仿真器。该模型基于林分尺度树形结构的地理扩展模型（Kohyama and Shigesada 1995）和林隙动态景观中具有树形结构的林分的移动斑块镶嵌模型（Kohyama 1993）。利用新的模拟装置对森林纬向地带性的响应进行了重新检验。与没有斑块镶嵌的情况（如Kohyama和Shigesada）相比，预测竞争相互作用形成的森林边界的移动速度略快，而在百年全球变暖之后的情况下仍有数千年的时间滞后。

This study was carried out to examine the formation and dynamics of the mosaic landscape of forest stand types with clear boundaries in subalpine forests of Hokkaido, northern Japan.Main research site was set on the western slope of Mount On'nebetsu of Shiretoko Peninsula, eastern Hokkaido. The mosaic landscape made by pure stands of Picea glehnii, and mixed stands of Abies sachalinensis, P. glehnii and Betula ermanii was described. Detailed census of core of, and margin between these two stand types showed that the discontinuous stand boundaries were not related to the edaphic conditions that changed gradually along the boundaries. Dynamic sequence around boundaries was from Picea -pure stands to mixed stands. The replacement process was hypothesized to be related to species difference in tolerance against aggravation by snow deposit on crown together with wind. Another site investigated was a successional landscape on the slope of Mount Komagatake in southern Hokkaido. The dynamic pattern of the invasion of Larix kampferi was analysed using sequential aerial photographs.As a generalized modelling tool, a new simulator was proposed through this study. The model is based on the geographically extended model of stand-level tree size structure (Kohyama and Shigesada 1995) and on the shifting patch mosaic model of stands with tree size structure in gap-dynamic landscape of forest (Kohyama 1993). The response of latitudinal forest zonation was re-examined using the new simulator. Compared to the case without patch mosaic (I.e. Kohyama and Shigesada), the forest boundaries made by competitive interaction was predicted to move slightly faster, while still millennia time lag was the case after centennial global warming.