ABSTRACT

We explored the dynamics of dwarf bamboo populations in a beech forest 11 years before and 30 years after clear-cutting. Repeated weeding or herbicide application (sodium chlorate) was used experimentally to reduce or eliminate dwarf bamboo prior to clear-cutting. At the beginning of the study, the understory comprised dense populations of two Sasa species, the dominant S. palmata and the less common S. kurilensis. Both weeding and herbicide application rapidly reduced the cover of S. palmata, but it began to recover prior to clear-cutting and soon exceeded initial cover values. Both weeding and herbicide application reduced the cover of S. kurilensis to near-negligible levels; the cover increased slowly after clear-cutting but remained below initial levels. Weeding or herbicide application resulted in different patterns with respect to height; height decreased rapidly in response to weeding, whereas herbicide application had more gradual effects. Height began to increase after clear-cutting, and S. palmata exceeded its initial height, reaching 1.5–2.0 m in the 10–15 years following clear-cutting. No tree recruits were found in sites where dwarf bamboo was left unmanaged. Weeding and herbicide application facilitated recruitment of Betula ermanii after clear-cutting, but recruits of Fagus crenata, which originally dominated the forest canopy, remained scarce or non-existent at 30 years after clear-cutting. We postulate that natural regeneration of Fagus is nearly impossible following clear-cutting in temperate beech forests in Japan with dense undergrowth of Sasa, even with advance measures to reduce or eliminate Sasa.

摘要

我们在原始砍伐之前的11年和之后30年探索了山毛榉森林中矮竹种群的动态。反复进行除草或除草剂（氯酸钠）的试验，是在清除之前先减少或消除矮竹。在研究开始时，林下层包括两种Sasa物种的密集种群，即占优势的S. palmata和较不常见的S. kurilensis。除草和除草剂的应用都迅速减少了棕榈链球菌的覆盖率，但在清除之前就开始恢复，很快就超过了初始覆盖率。除草和除草剂的施用均降低了库里链霉菌的覆盖率到几乎可以忽略的水平；清除后，覆盖率缓慢增加，但仍低于初始水平。除草或除草剂的使用导致了高度的不同模式。高度随着除草而迅速下降，而除草剂的施用则具有更多的渐进作用。明确切割后，高度开始增加，棕榈树超出其初始高度，在明确切割后的10-15年内达到1.5-2.0 m。在矮矮竹未得到管理的地点未发现新兵。清除杂草和除草剂后，可促进埃尔曼桦的募集，但山毛榉最初在森林冠层中占主导地位的树木，在砍伐后的30年中仍然稀缺或不存在。我们推测，即使在采用减少或消除Sasa的先进措施的情况下，在日本温带的山毛榉林中砍伐浅薄的Saasa，伐古斯（Fagus）的自然再生几乎是不可能的。