Effects of topography and historical human disturbance on the current-day distribution of Betula davurica in a secondary deciduous forest in central Japan

Abstract

ABSTRACT Betula davurica is a relict species in Japan of which distribution is influenced by topography at local scale. This species may also be dependent on disturbance for regeneration. However, no studies found that estimate and compare the effects of topography and human disturbance on abundance of this species. Focusing on abandoned charcoal kilns and charcoals in the surface soil as proxies for historical disturbance, we assessed the status of B. davurica in a secondary deciduous broad-leaved stand in central Japan. Although B. davurica was once a dominant species in the study area, its regeneration has stagnated after decline of charcoal production. The oldest individual was 90 years of age, suggesting that the current-day population established following a period of grassland dominance 100 years ago. We found multiple abandoned kilns, as well as widespread charcoal fragments in the surface soils of the study area. Both individuals, that had established prior to and following the decline of charcoal production, tended to be distributed at sites with other tree species with smaller DBH and at gentle slope. Location of charcoal kilns did not significantly affect the distribution of this species. It is possible that B. davurica prefers to gentle slope at the sites where historical logging for charcoal production and fire disturbance had influenced at the whole. Cessation of logging and fire disturbance have likely inhibited the regeneration of B. davurica. Logging of other tree species around at gentle slope may be necessary for the survival of this species.