제주고사리삼의 생장 특성 및 자생지의 식생 구조

Abstract

Mankyua chejuense is endemic to Korea, where it occurs only in the northeastern section of Jeju Island. There, it is distributed among sites that include Seonnheul-ri, Dongbok-ri and Gimnyeong-ri, which are less than 200 m above sea level. Vegetation in these three locations comprises stands of (i) evergreen broad-leaved trees and (ii) deciduous shrubs. Within the sites, Mankyua chejuense occurs in isolated swamp habitatat is lower elevations than the surrounding vegetation. Leaves of Mankyua chejuense began sprouting in July and expanded until December, after which they gradually withered and were shed ; leaves were absent until the following April. Leaf growth varied across seasons of sprout. Leaves that emerged in July grew normally, where as those that sprouted after September withered before becoming completely mature. Analysis of monthly species importance values in the herb layer showed that the ranking of Mankyua chejuense was similar to those of evergreen plants such as Liriope spicata and Ardisia japonica, whose dominance in the vegetation seemed to affect growth of Mankyua chejuense. There were 149 species of the vascular plants belonging to 114 genera in 61 families. Among the total, 138 species were angiosperms. We documented species composition and life forms of plants that appeared in the swamp habitat, showing that the percentages of annual and aquatic plants were high and markedly different from surrounding vegetation. We classified habitats of Mankyua chejuense in to two categories depending on swamp depth, rock coverage, dominant species identities, and surrounding vegetation composition. Vegetation differed between categories. Habitats with high rock cover were geographically differentiated from adjacent regions and were mostly vegetated with tree species that grow in humid environments, such as Ulmus parvifolia. In soil-rich habitats, swamps were shallow, soil layers were well developed, and trees such as Mallotus japonicus had been introduced from surrounding areas. Dominant species in the herb layers of both types, however, were aquatic plants that are characteristic of wetlands. In summary, Mankyua chejuense grew only in unique wetlands, such as marshes, that are shaded by trees for specific periods of the year. Consequently, to preserve Mankyua chejuense, it is crucial to maintain the wetland habitat in which it occurs. There is a pressing urgency to award protected status to both the habitats themselves and the surrounding tracts of vegetation.