Dynamics Of Dwarf Bamboo Populations And Tree Regeneration Over 40 Years In A Clear-Cut Beech Forest: Effects Of Advance Weeding And Herbicide Application

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.