Effects of small-scale clearcutting management on species diversity and vertical structure of understory vegetation of a conifer plantation comprising uneven-aged stands, in Kyushu, Southern Japan

We investigated the effects of small-scale clearcutting management on species composition and stratification of understory vegetation of a conifer plantation comprising stands of uneven age. Seven understory types were detected, which corresponded to the stand age of plantation patches. These understory types were characterized by degree of stratification and differences in composition of species characteristic habitats and life forms. There were few understory types in which all layers were fully developed in terms of tree abundance, indicating that the upper (sub-tree) layer limited the development of the lower (shrub and herb) layers. Similarly, no understory type had a high species diversity in all layers. Therefore, we suggest that managing stands of different age by the appropriate spatio-temporal arrangement of patches supports the various understory types, and thus maintains the complex structures and dynamics of the whole stand.