Separating the effects of land-use history and topography on the distribution of woody plant populations in a traditional rural landscape in Japan

Abstract

Many organisms depend on habitats in traditional rural landscapes, but only limited information is available on the distribution of woody plant populations as a consequence of land-use history, in spite of the expected strong effects of historical land use. Since the plot size in most vegetation surveys (several to dozens of meters) is too small to encompass woody populations, we examined the occurrence of 43 species in 100 plots measuring 200 m × 200 m (approximate seed dispersal distance) in a traditional rural landscape in Japan, and analyzed the effect of land-use history. Topographic conditions and land-use history are both key factors determining species distribution, but their correlation is often strong, so their effects are difficult to separate. We classified land use from 1910 to 2003, analyzed topography by cluster analysis, and used logistic regression to detect overall effects of each on the distribution of woody plant populations. We compared the effects of land-use history in the same topography in a two-way contingency table. Populations of naturalized exotic species and early successional species were found specifically in areas with a history of cultivation, which populations of many native species avoided. We detected significant overall effects of either topography or land-use history on species planted for timber production, probably owing to selection of plantation sites by people. A substantial part of the distribution of woody plants is a legacy of landuse history.