Study of habitat environment and species diversity-based on alien plant, Phytolacca americana L. in Korea.
The characteristics of 124 Phytolacca americana present areas and 88 surrounding absent areas over the country were investigated and compared from July 2016 to Sept 2017. The Phytolacca americana was confirmed as having been nationally distributed and is usually found in roadsides at an altitude of 380 m (26%), forest edges (24%), forests (19%), sunny spots (60%), dry soils (53%), sandy loams (31%) and sand + gravel soils (22%). 321 taxons consisting of 79 families, 209 genera, 289 species, 2 subspecies, 26 varieties and 4 cultivars and 286 taxons consisting of 76 families, 195 genera, 256 species, 2 subspecies, 24 varieties and 4 cultivars were found in the Phytolacca americana present areas and the absent areas, respectively. The relative net contribution degree was found highest in the Phytolacca americana (100) followed by Robinia pseudoacacia (29.4), Humulus japonicus (8.8) and Artemisia princeps (6.0) in the present areas, while it was found highest in Robinia pseudoacacia (100) followed by Humulus japonicus (44.4), Artemisia princeps (35.9), Pueraria lobata (18.6) and Setaria viridis (12.3) in the absent areas. The Raunkier's life form in the present/absent areas was found highest in the therophytes (34%/34%), followed by hemicryptophytes (17%/18%), megaphanerophytes and mesophanerophytes (18%/17%), nanophanerophytes (11%/11%) and geophytes (9%/11%). There was no significant difference in the species diversity between the present (2.141) and the absent (2.124) areas. However, the allelopathic agent and light blocked-out by the Phytolacca americana could possibly inhibit germination and the development of other species; especially, where a difference in species diversity was found high in forests, compared to other habitats (p=0.0605). Accordingly, it is suggested to review possible disturbances of native species habitats in shady spots including forest gaps, although the effect of Phytolacca americana on the ecological system in the suburban open and disturbed areas is not large.