Effects of previous land-use on plant species diversity in semi-natural and plantation forests in a warmtemperate region in southeastern Kyushu, Japan

We compared the species composition, occurrence and diversity of understorey of forestry plantations and seminatural secondary forests in a warm-temperate region in southeastern Kyushu, Japan, in which the previous land-use history had been documented. Cluster analysis and a stand ordination, using detrended correspondence analysis, indicated that plant species composition in forest stands was primarily influenced by the previous land-use history (as meadows or coppices) compared with either the current status of the stand (semi-natural forest or plantation) or site micro-topography. Species occurrence was also dependent on the previous land-use, with a significantly greater proportion of native woodland species being present in former coppice stands. Species richness, however, was higher in plantations and stands developing on former meadow sites. This was true of perennial forbs and climbing plants, but not the evergreen species which were originally common in native woodland of the region. Species diversity indices (Shannon’s Hʹ) showed a similar tendency to species richness. The light environment within forest stands, evaluated by gap light intensity (GLI) using hemispherical photography, had less effect on species richness. We conclude that previous land-use has a significant effect on the species composition and diversity of forest, persisting even after the establishment of conifer plantations, and that the restoration of the original ‘woodland’ species composition and diversity will require the retention of efficient seed sources near stands which have developed on land previously cleared of native forest cover.