Reforestation and Natural Regeneration Status of Non-Reforestation Land on Kyushu Island

Abstract

Non-reforestation land (NRL) affects the ecosystem services provided by forests, depending on the state of forest recovery. Although the presence of NRL has been already quantified, long-term monitoring of NRL after abandonment has not yet been carried out. We assessed areas of NRL that were present between 1998 and 2008 on Kyushu Island to identify whether they had been reforested by planting or by natural regeneration as of 2022. We also made a statistical analysis of the factors affecting reforestation and natural regeneration. Replanted and naturally regenerated forests accounted for 20 and 61％ of NRL, respectively. When combined with non-NRL, which was replanted immediately after clear-cutting, we found that 95％ of the clear-cut area had been restored to forest. We found that NRL with low density of Sika (Cervus nippon) or at higher elevations was more likely to be plantation forests. NRL on steep slopes, close to broadleaf forests, or at lower elevations, was more likely to be natural forest. We conclude that intensive forest management is required in NRL that is with high density of Sika, gently sloping, and far from broadleaf forests, because the probability of neither replanting nor natural regeneration is increased in this case.