Dr. Shigeru Miki (1901–1974) made great contributions to the fields of paleobotany, paleoecology, and plant taxonomy, including the discovery of Metasequoia Miki and the study of extant water plants. Details of Dr. Miki’s biography, the original description of Metasequoia, his collection of fossil and extant plants that are stored in the Osaka Museum of Natural History, the introduction of living Metasequoia to Japan, episodes of Dr. Miki’s life, and a list of Dr. Miki’s publications are presented in this paper. Dr. Miki was a scientist and colleague who spent his career being enthused with research of the natural world.

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The Tokiguchi and Seto Porcelain Clay Formations of the Tokai Group that are distributed in central Japan are characterized by the occurrence of Pinus trifolia Miki and many exotic, warm temperate taxa with such as the extinct genus Hemitrapa. Dr. Shigeru Miki described P. trifolia and many fossil species from the flora of these formations along with a new genus, Metasequoia. This paper reviews paleobotanical, stratigraphic, and sedimentological research of the porcelain clay formations since Miki’s work. The age of P. trifolia flora is now correlated to the latest middle Miocene to early late Miocene (10–12 Ma) based on fission track dating of the tephras.

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Taxodiaceous woods are among the most investigated in Lusatia (Central Europe) as well as in the European Cenozoic. Although these conifer genera have been known for a long time, the use of the generic names is confusing, especially in regard to their relationships to extant taxa. In Lusatia there occur some Taxodioxylon species with affinities to Sequoia, Cryptomeria, and Taxodium, Glyptostroboxylon species with affinities to Glyptostrobus and Cunninghamia, and also—paradoxically—one Cupressinoxylon wood with affinity to Taiwania. Extinct taxodiaceous woods also occur: Quasisequoioxylon and Juniperoxylon pachyderma ex parte. One Juniperoxylon was found with Cupressospermum saxonicum. The establishment of Quasisequoioxylon, a morphogenus, which shares xylotomic characters both with Taxodiaceae and Cupressaceae s.s., is considered to represent the wood of the extinct genus Quasisequoia. Rediscovery of the original preparation of Glyptostrobus tener Kraus, the basionym for Glyptostroboxylon tenerum (Kraus) Conwentz, enabled a detailed re-assessment of this taxon and an emended diagnosis for the genus Glyptostroboxylon. The most common morphogenus is Taxodioxylon, because the wood species it includes have affinities to many extant genera: Taxodium, Cryptomeria, Sequoia, Metasequoia, and Sequoiadendron. Taxodioxylon was erected by Hartig in 1848 with the type Taxodioxylon goeppertii. Gothan emended this taxon in 1905. Greguss and Blokhina have used the names Sequoioxylon as well as Metasequoioxylon, but these taxa fit under the broadly defined morphogenus Taxodioxylon. It is proposed that a revision of Taxodioxylon should be made. One Cupressinoxylon wood is most similar to Taiwania. The xylotomical investigations supplemented by information from other organs, especially dispersed cuticles—using the whole-plant concept—provide data for reconstructing the woody plant communities that contributed to Miocene peat formation in Lusatia. The xylotomical records suggest the transition of a relatively eutrophic stage with Glyptostrobus, via a mesotrophic stage with Sequoia, Cunninghamia, and Taiwania towards an oligotrophic habitat with Cryptomeria.

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An in situ late Miocene (Pannonian) fossil forest preserved as wood has been uncovered at Bükkábrány, Hungary. Excavation within the open-pit mine revealed 16 stumps that ranged from 1.8 to 3.6 m in diameter at the base and up to 6 m in height preserved atop a 16 m thick coal seam. A relative change in the elevation of Lake Pannon appears to have drowned the forest about 7 Ma ago. Sand deposited as part of a prograding delta covered the landscape and preserved the trunks in a waterlogged condition. Forest stand density was 36 stems per hectare. The trees grew 3 to 16 m apart. Their diameter at breast height ranged from 137 to 248 cm. Stem basal area varied from 3.46 to 8.44 m2 per tree, yielding a forest basal area of 240 m2/ha. The tree height was probably 44 to 52 m and the stem volume ranged from 44 to 125 m3. The total biomass of 1400 t/ha is estimated for the Miocene Bükkábrány forest. The net annual primary production was in the range of 2.8 t/ha.

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The research history and stratigraphic occurrence of Taxodiaceae macrofossils from the Plio-Pleistocene sediments in central Japan were reviewed and the process of survival and extinction of the Taxodiaceae are discussed. Taiwania and Sequoia became extinct in the late Pliocene and the earliest Early Pleistocene. Metasequoia and Glyptostrobus became extinct in the latest Early Pleistocene. Cunninghamia survived up to the Middle Pleistocene and then became extinct. The extinction of these genera occurred in and around the well-defined stages of global climatic deterioration as shown in the marine oxygen isotope curves. During the same period the uplift of mountains around sedimentary basins increased and should have caused the other conifers including Cryptomeria, Cupressaceae, and Pinaceae to increase in abundance. The flood plain habitat of Metasequoia and Glyptostrobus was susceptible to orogenic and eustatic events that became more prevalent during the late early Pleistocene. Active uplift of mountains fragmented the alluvial lowlands and restricted the movement of Metasequoia and Glyptostrobus as climate and sea level changed.

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Spatial changes in the distribution of Cryptomeria japonica D. Don since the last interstade were reconstructed based on the pollen records from Shikoku Island, southwestern Japan. During the last interstade, C. japonica was dominant throughout the island and then conspicuously declined toward the end of this period, except around the Ikeyama-ike Bog, Muroto Peninsula on the Pacific Ocean side of Shikoku Island. During the pre-full glacial to late glacial periods, C. japonica was not abundant on Shikoku Island, except around the Ikeyama- ike Bog and Azono Valley on the Kochi Plain. The occurrence of Cryptomeria pollen during this period implies that these areas served as refugia for C. japonica during the full-glacial period. During the early part of the post-glacial period, warm-mixed/broad-leaved evergreen forests dominated by Quercus subgen. Cyclobalanopsis and Castanopsis rapidly expanded in the coastal region on the Pacific Ocean side. However, C. japonica was not a co-dominant component in these forests throughout this period, except in the areas around several sites such as the Ikeyama-ike Bog, where C. japonica rapidly increased in quantity during the late part of this period.

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John E. Kuser (1925–2008) was a Professor of Forestry at Rutgers University from 1981 to 2001. Dr. Kuser did not enter academia until he was over 50 years old, yet he made many important contributions to forestry research. Much of his research focused on Metasequoia glyptostroboides Hu et Cheng, which he believed showed great promise as a horticultural and economically valuable species. Here we trace Dr. Kuser’s life and career and summarize his contributions to Metasequoia research and forestry in general.

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We measured bulk δ13C and δ15N values and carbon and nitrogen elemental concentrations of leaves collected from Metasequoia glyptostroboides Hu et Cheng trees cultivated at 39 sites across the United States under different latitudes and climatic regions. δD values from south-facing leaf n-alkanes of 27 trees were also determined. Climate data over the past 50 years (1950–2009) were compiled from stations near each site. Isotope data were cross plotted against each geographic and climatic parameter, including latitude, annual mean temperature (AMT), spring (February–May) mean temperature (SMT), annual mean precipitation (AMP), and spring mean precipitation (SMP). Statistical analyses revealed the following significant correlations: 1) a strong negative correlation between n-alkane δD and latitude; 2) statistically significant correlations between δD and both AMT and SMT; 3) a weaker but still significant correlation between δD and SMP; 4) statistically significant relationships between carbon concentration and both temperature and precipitation parameters, especially AMP; 5) an unexpected correlation between nitrogen concentration and SMP. These results bear strong implications for using δ13C and δD values obtained from fossil Metasequoia as paleoclimatic and paleoenvironmental proxies.

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The nine genera and thirteen species that were formerly included in the family Taxodiaceae represent a unique and fascinating group of conifers. Throughout much of their Cretaceous and Tertiary history many were significant components of the mid- to high-latitude Northern Hemisphere forests and grew under a range of ecological, environmental, and climatic conditions. Global cooling and increasing aridity following the Eocene-Oligocene boundary led to a hemisphere-wide contraction of their overall distribution. Increased climatic instability during the Plio-Pleistocene intensified this process and by the start of the Holocene most species were restricted to small areas in eastern Asia and southern and western North America. The Holocene has been characterized by wide ranging changes associated with the development and expansion of human civilizations, especially over the last two centuries. The rapid expansion of agriculture, industrialization, and urbanization has severely impacted almost all species. Nine are currently listed as critically endangered, endangered, or vulnerable on the International Union for Conservation of Nature and Natural Resources’ (IUCN’s) Redlist of Threatened Species. This paper reviews the current conservation status of all thirteen species and discusses their prospects for the immediate future. There is a special focus on Glyptostrobus pensilis (Staunton ex D. Don) K. Koch.

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Fossil evidence from Metasequoia-dominated forests continue to inform us as to how forests have responded to past climate change. As such, these Metasequoia findings and those of other high-latitude Northern Hemisphere forest tree species set rigorous standards for considering the case study of a Southern Hemisphere conifer, Fitzroya cupressoides. Tree ring analyses, fossils, glacial geology, and molecular evidence together piece together a remarkable case study. Fitzroya cupressoides, a site-specific endemic, persisted within its current range in Chile throughout the Late Pleistocene, surviving glaciers, volcanoes, and earthquakes. Here, we present a review for this Fitzroya case study, which is followed by a synthesis of research questions which could elucidate how forest species persisted locally over the course of Quaternary climate change.

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The identification and classification of isolated fossil leaves of the Taxodiaceae is generally difficult when the remains are not associated with reproductive organs. These problems are further exacerbated when more than one genus of the Taxodiaceae and/or genera of the Taxaceae or Cephalotaxaceae are preserved in the same deposits or the quality or mode of preservation precludes confident identification. To help facilitate the identification and separation of isolated taxodiaceous fossil leaves, the leaves of extant representatives of Cephalotaxus Siebold et Zuccarini ex Endlicher, Glyptostrobus Endlicher, Metasequoia Hu et Cheng, Sequoia Endlicher, Taxodium Richard, Taxus L., and Torreya Arnott were examined. The results of this investigation provided sufficient data about external morphological features to establish a system of classification for leaves that could be used to assist in the identification and classification of isolated fossil leaves.

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Applicability of near infrared (NIR) spectroscopy to identify species of degraded and aging solid wood was examined among species important to Japanese art history and archaeology. NIR spectra were obtained from wood blocks of five softwood species collected over the last 80 years from various sites and stored in the wood library of the Forestry and Forest Products Research Institute, Tsukuba in Japan. Partial least square (PLS) discriminant analysis was employed for the separation of three pairs of species, i.e., Chamaecyparis obtusa and Torreya nucifera, Chamaecyparis obtusa and Chamaecyparis pisifera, Thuja standishii and Cryptomeria japonica. The effects of spectral pre-processing and wavelength range were also evaluated. Under the limitation of sample volume, PLS discriminant analysis calibrated using second derivatives and wavelengths spanning 830 to 1150 nm could separate the samples into each pair of species in the 100 % accuracy. These results suggest that NIR spectroscopy combined with PLS discriminant analysis is a powerful technique for distinguishing species for degraded and aging wood nondestructively without any sample preparations.

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Wood anatomical variation of Japanese species of Cupressaceae was studied to evaluate the possibility of identifying the species. Species of Cupressaceae have been important forest resources in Japan since prehistoric periods, and huge quantities of them were transported and used throughout Japan in the early modern Edo period. Thus, species-level identification of species of Cupressaceae is indispensable to clarify prehistoric and historic use of timber in Japan. To evaluate the possibility of distinguishing the species of Cupressaceae, quantitative variation in features of cross-field pitting and rays were studied among seven Japanese species of five genera. Although variation ranges overlapped considerably, size, type, and frequency of cross-field pitting allowed identification of these species if individual averages were compared. Ray height and frequency, which are highly affected by the level of cambial activity, mostly overlapped among the studied species and could not be used for identification. This study confirmed the possibility of distinguishing the species by traditional criteria, but also revealed new criteria to be considered in future identification.

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