Effect on Changes of Understory Plant Distribution After Thinning Japanese Cedar Forests Around Geomunoreum

Abstract

This study investigated the change in understory plant distribution to find out the effect of cedar(Cryptomeria japonica) thinning on the diversity of plant species in the Geomunoreum of J e ju Island, the purpose of which was to restore natural vegetation. The vascular plants identified in the thinned plantations for 5 years from 2018 were a total of 95 taxa including 51 families, 79 genera, 86 species, 1 subspecies and 8 variants. This showed a higher number of species compared to 52 taxa in the unthinned plantations and 67 taxa in the natural forest stand. The floristic target plants were identified: 25 taxa in the thinned plantations, 14 taxa in the unthinned plantations, and 25 taxa in the natural forest. For 4 years after 2018, an increase of 40 species in the thinned plantations showed the highest rate of increase, followed by natural forests with 33 species and unthinned plantations with 23 species. The species richness increased in both thinned and unthinned plantations, 3.16 and 1.10 respectively which is lower than 4.11 in natural forests. The species diversity with an elapsed time of 6 years after thinning rose 3.64 in the thinned plantations, 3.42 in the natural forest and 3.21 in the unthinned plantations. The growth of diameter of the breast height was higher than that in the unthinned plantations. It is considered that the diversity of plant species in the thinned plantations around Geomunoreum is changing similarly to the surrounding natural forest as the number and population of newly emerging plant species increase.