Kyungsik Kim

Variation of silica bodies in leaf epidermal long cells within and among seventeen species of Oryza (Poaceae).

Morphometric procedures were used with scanning electron microscopy backscattered images to study silica bodies in epidermal long cells of four different leaf veins of 17 of the 20 species of Oryza. The veins studied were midrib, large vein, small vein, and marginal vein. Image analysis was used to study morphological variations among the silica bodies. Statistical analyses were based on 11 variables. Even within a single leaf, silica bodies were not uniform. However, the degree of morphological variation normally showed a distribution of morpholgical types around one modal shape. The most significant differences observed were between silica bodies of the midrib and those of other veins. Bodies varied with respect to both size and shape. Computer-assisted image analysis is an effective tool for categorizing basic data and for statistical analysis of variation among silica bodies. Morphological variation among silica bodies of a single leaf may be related to water-conducting systems and their influence on silica availability and phytolith formation.

Comparison of Korean and Japanese Tertiary fossil wood floras with special references to the genusWataria

Among 64 fossil woods collected from the Upper Coal-bearing Formation of Janggi Group, Pohang, Korea, four specimens have been characterized by their distinct ring porosity and the presence of tile cells in rays. After detailed anatomical studies, we could identify them as two species ofWataria-W. miocenica andW. parvipora. GenusWataria, known as an extinct taxon of Sterculiaceae, has been found only in the Tertiary formations in Japan. Most of these sterculiaceous plants are thermophilic and reportedly never inhabited in the Korean Peninsula. The existence of fossil woods ofWataria in Korea supports the idea of a common flora established in both countries during the Tertiary. In Japan, fossil woods ofWataria have been found only during the early Miocene formations. Therefore, the age of the Upper Coal-bearing Formation can be said of as the early Miocene.

Some confierous fossil woods from the Cretaceous of Korea

Thirteen silicified fossil woods were collected from the Cretaceous deposits of Haenam Basin and islands of Gwanmae and Byeongpung, Jeollanam-do as well as from the Cretaceous Dadaepo Formation, Busan, Korea. Anatomical features of all of these specimens showed that they were coniferous woods. On the basis of the detailed anatomical features they were identified asDadoxylon byeongpungense sp. nov.,Cupressinoxylon uhangriense sp. nov.,Taxodioxylon cf.nihongii Nishida et H. Nishida,Taxodioxylon albertense (Penhallow) Shimakura, andMesembrioxylon sp. All of them, exceptMesembrioxylon, are described for the first time from the Korean Peninsula. It should be noted that no dicotyledonous wood has been found from this study. Generally the sampled horizons are considered as Upper Cretaceous with dinosaur footprint fossils. In Japan, the Upper Cretaceous sediments bear abundant dicotyledonous fossils. Therefore further studies should be needed to clarify the age of these horizons and the vegetation in the ancient world with dinosaur.

Xenoxylon Synecology and Palaeoclimatic Implications for the Mesozoic of Eurasia

The distribution of fossil wood genera has been demonstrated to be an effective proxy for Mesozoic terrestrial climates. In this study, we investigated the phytocoenoses, which were associated with Xenoxylon confirmed to be a marker for a cool and/or wet climate in a boreal hemisphere (i.e., Xenoxylon-phytocoenoses) during the Mesozoic, using specimens of fossil wood. It was confirmed that Xenoxylon co-occurs more often with some wood genera than with others. For example, Protocedroxylon, a wood that is most likely related to the Pinaceae, is the genus most often associated with Xenoxylon-phytocoenoses. Although Taxodioxylon is also found in Xenoxylon-phytocoenoses, it is not found, however, as consistently as Protocedroxylon. The distribution and diversity of Xenoxylon-phytocoenoses changed throughout the Mesozoic. During the Late Triassic and Late Cretaceous, Xenoxylon-phytocoenoses had low diversity and were restricted to higher palaeolatitudes during the Late Cretaceous. However, during the Early to Middle Jurassic, Xenoxylon-phytocoenoses were distributed much farther south, while their diversity concomitantly increased sharply. From the Late Jurassic to the Early Cretaceous, the distribution of Xenoxylon-phytocoenoses moved northward in Europe and even more so in East Asia. The changes in the distribution of Xenoxylon-phytocoenoses are in agreement with changes in both global and regional climates. Our results also demonstrated that, within the Xenoxylon distribution range, the corresponding phytocoenoses were differentiated along a latitudinal gradient and according to the global climate change patterns during the Mesozoic.

Miocene Tilia (Malvaceae) woods in Korea: including a new taxon

The Miocene fossil woods with Tilia affinity have been described for the first time in Korea. Two specimens of them were discovered from the fluvial deposits of the Sinjeongri (Lower Coal-bearing) Formation of the Janggi Basin at Donghae-myeon, Pohang City, and one specimen was identified from an exhibited collection in a local company of Ulsan City. These specimens were identified as a new taxon of Tilia wood from the Neogene; that is Tilia koreana sp. nov. Jeong, E.K. et Kim, K. One of the two specimens from the Sinjeongri Formation was identified up to genus level due to poor preservation.

Daijima-type conifer wood assemblage of the Hatamura Formation (Middle Miocene) in the Akita Prefecture, Japan

The paleofloral change from the Aniai-type to the Daijima-type during the Miocene is the most distinctive and representative one of the six floral changes in the Japanese Archipelago during the Tertiary. These floral types are based mainly on compressed or imprinted leaf fossils. In Korea, the transition-type between the Aniai- and Daijima-type floras has been proposed based on the fossil wood assemblages, and the Hatamura Formation, which is the same age as the Daijima Formation, has yielded abundant fossil woods. To confirm whether the fossil wood assemblages are in agreement with the paleofloras inferred from fossil leaves, the fossil woods from the Hatamura Formation were studied. We found that warm temperate and daijiman elements, such as Keteleeria, Taxodioxylon cunninghamioides, T. sequoianum and Pinus, were present in the Hatamura Formation. Therefore, it can be concluded that the fossil wood types from the Hatamura Formation agree well with the Daijima-type Flora. This result, in turn, verifies the existence of transitional flora between the Aniaiand Daijima-types in Northeastern Asia.

Oligocene-Neogene fossil history of Asian endemic conifer genera in Japan and Korea: Fossil history of Asian endemic conifers in Japan

Temporal and spatial changes of ten conifer genera that are endemic to East Asia were analyzed based on fossil data from humid temperate forests in the Japanese Islands and Korean Peninsula to elucidate the phytogeographic history, and to understand differences between those genera eliminated from the Japanese Islands and those that remained extant. All these genera, except for Thujopsis, have existed in the area since the Paleogene and remained in the Japanese islands after initial separation from the continent at the early–middle Miocene. Fossil representatives of locally extinct six genera have tendencies to adapt to wider ranges of climatic conditions than their modern relatives. Metasequoia, Glyptostrobus, and Taiwania began to change their distributions since the late Miocene possibly through habitat partitioning. Keteleeria, Pseudolarix, and Cunninghamia appeared to have expanded their habitat toward warmer conditions during the mid‐Miocene Climatic Optimum and then became restricted to warmer forest vegetation by the end of Pliocene. Overall changes in their distribution can be explained by climatic effects. On the contrary, three genera endemic to Japan (Sciadopitys, Cryptomeria, and Thujopsis) followed clearly different trends from the others. Cryptomeria and Thujopsis were especially adapted to cooler‐temperate climate and they retained their habitat areas in the northern part of Japan. During the late Miocene–Pliocene, the islands connected with the Eurasian continent again, which probably acted as a corridor for warm‐adapted genera to disperse southwest. Current data suggest that ecological requirements of each genus might be essential to determine whether they could survive on the Japanese Islands.

Miocene fossil plants from the Eoil Basin (Gampo area), Gyeongju, Korea

The Eoil Flora, from two sites of the Gampo Conglomerate and one site of the Eoil Formation in the Eoil Basin, consists of 17 species belonging to 11 families and two angiosperms of uncertain systematic position. The following 14 genera are represented: Equisetum, Sorbus, Ulmus, Fagus, Pterocarya, Alnus, Populus, Salix, Decodon, Acer, “Alangium”, Fraxinus, Dicotylophyllum and Monocotylophyllum. The flora consists mainly of deciduous broad-leaved tree species, dominated by Alnus arasensis followed by “Alangium” aequalifolium. The Eoil Flora represents riparian and surrounding vegetation, as indicated by the mode of fossil occurrence, lithology and sedimentary facies of the plant-bearing beds. The Eoil Flora is comparable to the Janggi Flora of the Pohang area and the Aniaitype floras of Japan. Aniai-type floras, including the Eoil Flora, share features common to broad-leaved deciduous vegetation under mesic to humid temperate climates. This flora also characterizes the paleoenvironment of this region just before the tectonic event associated with the opening of the East Sea (Sea of Japan).