The Geomunoreum Lava Tube System, declared as a UNESCO World Heritage Site, has a unique natural ecosystem. The information available about this ecosystem, which contains lava caves with secondary carbonate speleothems, is sparse. Hence, extensive research is warranted for establishing a conservation standard. We commenced microbial research on the system and have been studying the microorganisms coating the lava tube wall to acquire fundamental information for understanding the lava cave ecology of Jeju Island. Samples were collected from yellow-colored walls in six caves that are part of the system―the Bengdwi, Utsanjeon, Bukoreum, Manjang, Gimnyeong, and Yongcheon caves. This study focused on yellow walls as it is the most easily distinguished color. According to previous studies, the color of cave walls is attributed to microorganisms or their components. To determine whether the yellow mats from the Jeju lava tube walls are caused by microorganisms, we examined samples at the microscopic scale, by staining mats and analyzing bacterial isolates from glitter particles. As a result, we found that the yellow walls of lava tubes are comprised of microbial mats.

Lava caves could be useful as outposts for the human exploration of the Moon. Lava caves or lava tubes are formed when the external surface of the lava flows cools more quickly to make a hardened crust over subsurface lava flows. The lava flow eventually ceases and drains out of the tube, leaving an empty space. The frail part of the ceiling of lava tube could collapse to expose the entrance to the lava tubes which is called a pit crater. Several pit craters with the diameter of around 100 meters have been found by analyzing the data of SELENE and LRO lunar missions. It is hard to use these pit craters for outposts since these are too large in scale. In this study, small scale pit craters which are fit for outposts have been investigated using the NAC image data of LROC. Several topographic patterns which are believed to be lunar caves have been found and the similar pit craters of the Earth were compared and analyzed to identify caves. For this analysis, the image data of satellites and aerial photographs are collected and classified to construct a database. Several pit craters analogous to lunar pit craters were derived and a morphological pit crater model was generated using the 3D printer based on this database.

This study was conducted to provide scientific information for establishing efficient and systematic measures for nature conservation and management in Manjang-gul lava tube. The number of vascular plants was 204 taxa (82 families, 176 genera, 144 species, 1 subspecies, 26 varieties and 1 forma). Of those, pteridophyte were 5 families, 12 genera, 14 species and 1 variety and gymnosperm were 4 families, 6 genera, 5 species and 1 variety. Seventy three families, 149 genera, 157 species, 1 subspecies, 24 varieties and 1 forma in angiosperm composed of 62 families, 123 genera, 137 species, 1 subspecies, 17 varieties and 1 forma in dicotyledon and 11 families, 26 genera, 20 species and 7 varieties in monocotyledon. The number of naturalized plants was 9 families, 17 genera, 18 species and 3 varieties, totaling 21 taxa.