Ben A. LePage

Evolutionary History of the Genus Pseudolarix Gordon (Pinaceae)

The fossil record of Pseudolarix (Pinaceae) reveals wide distribution in North America and Eurasia from at least the Early Cretaceous (Berriasian) and possibly the Late Jurassic (Portlandian) to the Plio-Pleistocene. Several hundred reproductive and vegetative remains, representing two species of Pseudolarix, were recovered from sediments of Eocene age on Axel Heiberg and Ellesmere Islands, Canadian Arctic Archipelago. These specimens form the basis for reassessment of the fossil record of the genus and evaluation of morphology and variability of seed-cone scales, winged seeds, leaves, and brachioblasts. Unfortunately, most reports of Pseudolarix lack sufficient details of the character traits of the cone scales, particularly those of the bracts, that are required for identification at the species level. Following review of the known fossil record, only two species are recognized, discrimination being based on differences in length and morphology of the bract subtending the cone scale. One species, the short-bracted form, possesses anatomical and morphological features that conform entirely to the living species P. amabilis (Nelson) Rehder. On the basis of the now considerable data available for both living and fossil material, segregation of the fossil as a distinct species cannot be justified. As interpreted, P. amabilis is an extraordinary example of evolutionary stasis. The second species, P wehrii Gooch, a long-bracted form, appears to represent an extinct lineage of limited range. The spatial and temporal distribution pattern of fossil Pseudolarix indicates that displacement between Eurasia and North America from the Late Jurassic/Early Cretaceous to the Plio-Pleistocene occurred through Beringia and the newly defined Spitsbergen Corridor; the North Atlantic routes were apparently not used by Pseudolarix. Displacement into Europe from eastern Asia was delayed until regression of the Turgai Strait and late Tertiary, after significant global climatic deterioration.

Reconstruction of Tertiary Metasequoia forests. II. Structure, biomass, and productivity of Eocene floodplain forests in the Canadian Arctic

Abstract Abundant fossil plant remains are preserved in the high-latitude middle Eocene deposits of the Buchanan Lake Formation on Axel Heiberg Island, Nunavut Territory, Canada. Intact leaf litter, logs, and stumps preserved in situ as mummified remains offer an opportunity to determine the structure, biomass, and productivity of two Taxodiaceae-dominated forests that grew north of the Arctic Circle (paleolatitude 75–80°N). We excavated fossil tree trunks and treetops to develop equations that describe the height, structure, and mass of the aboveground components of Eocene-age Metasequoia trees. We combined those data with surveys of in situ stumps to determine the structure, biomass, and productivity of two fossil forests, “N” and “HR.” We calculated a canopy height of 40 ± 3 m for the N forest and 25 m ± 2 m for the HR forest. Buried knots in dissected logs and abundant branch-free bole wood indicate that these were tall, closed-canopy forests. Stem tapers indicate that the overstory was of uniform height. Stem volume equaled 2095 m3 ha−1 and stem biomass was 628 Mg ha−1 in the N forest. Volume and biomass in the HR forest were much smaller, 211 m3 ha−1 and 63.3 Mg ha−1, respectively. We estimated understory tree biomass to be 40 Mg ha−1 in the N forest and 3.5 Mg ha−1 in the HR forest. Recovery of seven fossil treetops with exposed branch stubs enabled us to make estimates of branchwood and foliar biomass using allometric equations derived from modern, plantation-grown Metasequoia glyptostroboides. Estimated stand-level branch biomass was 13 and 6.7 Mg ha−1 in the N and HR forests, respectively. Standing foliar biomass was estimated to be 3.2 and 2.1 Mg ha−1 in the N and HR forests, respectively. Using annual ring widths, the reconstructed parabolic stems, and wood density of modern Metasequoia, we calculated annual wood production to be 2.3 Mg ha−1 yr−1 for the N forest and 0.55 Mg ha−1 yr−1 for the HR forest Assuming that the ancient Metasequoia were deciduous like their living relatives, annual aboveground net primary productivity was 5.5 Mg ha−1 yr−1 for the N forest and 2.8 Mg ha−1 yr−1 for the HR forest. Our estimated biomass and productivity values for N are similar to those of modern old-growth forests of the Pacific Northwest of the United States and old-growth coastal Cordillera forests of southern Chile.

The Geobiology and Ecology of Metasequoia

PART I - FOSSIL METASEQUOIA AND HISTORY Chapter 1 - The Evolution and Biogeographic History of Metasequoia Ben A. LePage, Hong Yang and Midori Matsumoto Chapter 2 - Paleoecology and History of Metasequoia in Japan, with Reference to its extinction and Survival in East Asia. Arata Momohara Chapter 3 - A High-Resolution Palynological Analysis, Axel Heiberg Island, Canadian High Arctic Suzanna L. Richter and Ben A. LePage Chapter 4 - Metasequoia in the Oligocene Bridge Creek Flora of Western North America: Ecological Implications and The History of Research Herbert W. Meyer Chapter 5 - Gunthers Travels: The Odyssey of Metasequoia Seeds from the 1920s? Judy Barrett Litoff PART II - CUTICLE, ULTRASTRUCTURE AND BIOMOLECULES Chapter 6 - Cuticle Analysis of Living and Fossil Metasequoia Qin Leng Chapter 7 - Ultrastructural Preservation in Middle Eocene Metasequoia Leaf Tissues from the Buchanan Lake Formation Karimah Schoenhut Chapter 8 - Biomolecules from Living and Fossil Metasequoia: Biological and Geological Applications Hong Yang PART III - ECOLOGY AND ECOPHYSIOLOGY Chapter 9 -Ecological Characteristics of Metasequoia glyptostroboides Christopher J. Williams Chapter 10 -Physiological Ecology of Metasequoia glyptostroboides Hu et Cheng David R. Vann Chapter 11 -Competitive Advantages of Metasequoia in Warm High Latitudes Richard Jagels and Maria A. Equiza PART IV - CULTIVARS AND HORTICULTURE Chapter 12 -Selecting and PropagatingNew Cultivars of Metasequoia John Kuser Chapter 13 - Cultivars of Metasequoia glyptostroboides Christophe Nugue Chapter 14 - A Conservation Plan for Metasequoia in China Gaytha A. Langlois

A Dendroctonus bark engraving (Coleoptera: Scolytidae) from a middle Eocene Larix (Coniferales: Pinaceae): early or delayed colonization?

An engraving made by a scolytid bark beetle, assigned to the genus Dendroctonus of the tribe Tomicini, has been identified on a mummified, middle Eocene (45 Ma) specimen of Larix altoborealis wood from the Canadian High Arctic. Larix altoborealis is the earliest known species of Larix, a distinctive lineage of pinaceous conifers that is taxonomically identifiable by the middle Eocene and achieved a broad continental distribution in northern North America and Eurasia during the late Cenozoic. Dendroctonus currently consists of three highly host-specific lineages that have pinaceous hosts: a basal monospecific clade on Pinoideae (Pinus) and two sister clades that consist of a speciose clade associated exclusively with Pinoideae and six species that breed overwhelmingly in Piceoideae (Picea) and Laricoideae (Pseudotsuga and Larix). The middle Eocene engraving in L. altoborealis represents an early member of Dendroctonus that is ancestral to other congeneric species that colonized a short-bracted species of Larix. This fossil occurrence, buttressed by recent data on the phylogeny of Pinaceae subfamilies and Dendroctonus species, indicates that there was phylogenetically congruent colonization by these bark-beetle lineages of a Pinoideae + (Piceoideae + Laricoideae) host-plant sequence. Based on all available evidence, an hypothesis of a geochronologically early invasion during the Early Cretaceous is supported over an alternative view of late Cenozoic cladogenesis by bark beetles onto the Pinaceae. These data also suggest that host-plant chemistry may be an effective species barrier to colonization by some bark-beetle taxa over geologically long time scales.

Taxodium wallissii Sp. Nov.: First Occurrence of Taxodium from the Upper Cretaceous

Exceptionally well-preserved silicified remains of a new species of Taxodium have been recovered from the Late Cretaceous (ca. 70 million years old) sediments of the Horseshoe Canyon Formation near Drumheller, Alberta, Canada. Specimens include three-dimensionally preserved branches bearing dimorphic leaves, pollen cones, pollen, seed cones, and seeds. The abundance and quality of preservation of these remains have allowed for detailed examination of morphological and anatomical features for comparison with extant representatives of the Taxodiaceae. The vegetative axes bear taxodioid leaves and rare cupressoid leaves; staminate and pistilate axes are subtended entirely by cupressoid leaves. The seed cones are erect, short-stalked, and globose, arranged alternately on branches, and bear up to fifteen helically arranged, deciduous bract-scale complexes. Each cone scale bears two more or less triangular seeds. Vasculature and arrangement of the resin canals of the cone scales are much more complex than that of any of the extant species examined. The pollen cones are typical of extant Taxodium; the pollen grains are structurally comparable, but small when compared with extant representatives of the genus. Comparison of these fossils with extant representatives of the Taxodiaceae indicate that they are most similar to Taxodium, but are comparable to Glyptostrobus and Cryptomeria in some features. The Horseshoe Canyon Taxodium is the first unequivocal report of Cretaceous Taxodium from North America and provides insight into the early evolution of the genus and phylogenetic relationships among other representatives of the family.

The Fossil Fungi of the Princeton Chert

The middle Eocene Princeton chert locality in southern British Columbia, Canada, contains one of the best-preserved permineralized Tertiary floral assemblages known in North America. The quality of preservation of the vascular plant and fungal remains is exquisite because anatomical and morphological features have been preserved at the cellular level. Past studies indicate the vascular flora is rich in species diversity and abundance and includes the in situ remains of semiaquatic and aquatic plant communities. Our initial assessment of the fungi in this assemblage indicates a diverse fungal community had developed and that many of the component species are comparable to modern taxa. Fossil fungi include unilocular and multilocular stromatoid fructifications on leaves and fruits. These are comparable to three extant representatives of the Dothideales or eustromatic Coelomycetes of the Fungi Imperfecti. Two of these contain septate conidia but no ascospores. The third lacks spores but resembles the loculoascomycete genus Mycosphaerella in size and structure of the uniloculate stromata. Fossil representatives of the Hyphomycetes include a seed-borne sclerotic fungus similar to Alternaria and, in the rhizomes of an aquatic plant, Cercospora-like conidia along with moniliform cells that resemble those formed by the genus Rhizoctonia. The teliospores of an anthericolous smut are present in the anthers of an unidentified flower. This fungus is most similar to Microbotryum violaceum, a smut fungus that occurs in the anthers of Caryophyllaceae. The continuing study of the Princeton Chert is allowing us to better understand the role of these, and other, fungal constituents in early Tertiary semiaquatic/aquatic plant communities.

Structure, allometry, and biomass of plantation Metasequoia glyptostroboides in Japan

We quantified structural features and the aboveground biomass of the deciduous conifer, Metasequoia glyptostroboides (Hu and Cheng) in six plantations in central Japan. In order to derive biomass estimates we dissected 14 M. glyptostroboides trees into three structural components (stem wood, branch wood and foliage) to develop allometric equations relating the mass of these components and of the whole tree to diameter at breast height (DBH). We found robust relationships at the branch and whole tree level that allow accurate prediction of component and whole tree biomass. Dominant tree height was similar within five older (>40 years) plantations (27‐33 m) and shorter in a 20-year-old plantation (18 m). Average stem diameter varied from 12.8 cm in the youngest stand to greater than 35 cm in the oldest stand. Metasequoia have relatively compact crowns distributed over the top 30% of the tree although the youngest stand had the deepest crown relative to tree height (up to 38%). At the individual tree level in older stands, 87% of the aboveground biomass was allocated to the stem, 9% to branch wood and 4% to foliage. We found little difference in the relative distribution of above ground biomass among the stands with the exception of lower foliage biomass in larger diameter trees. Total aboveground biomass of the older stands varied twofold, ranging from a maximum of 450 Mg ha ! 1 in a 42-year-old stand to a minimum of 196 Mg ha ! 1 in a 48-year-old stand. Total above ground biomass of the 20-year-old stand was 176 Mg ha ! 1 .

A new species of Thuja (Cupressaceae) from the Late Cretaceous of Alaska: implications of being evergreen in a polar environment.

A branch bearing a number of seed cones of Thuja L. (Cupressaceae) has been recovered from a Late Cretaceous (Turonian) deposit from the North Slope of Alaska. This reproductive material is the oldest known for the genus and is indistinguishable from the seed cones of most of the extant species of Thuja, indicating that the seed cones of this Alaskan fossil Thuja had attained a modern morphological appearance early in the evolutionary history of the genus. From a physiological standpoint, the ability of modern species of Thuja to tolerate cold to freezing conditions and the ability of fossil representatives of the genus to survive periods of extended darkness during the polar winters supports the contention that the polar winters during the Late Mesozoic and early Cenozoic were cold.

Permineralized fruits of Diplopanax (Cornaceae, Mastixioideae) from the middle Eocene Princeton chert of British Columbia

Over 80 specimens of a permineralized fruit referable to the Cornaceae (Mastixioideae) have been recovered from the middle Eocene Princeton chert (Allenby Formation) of British Columbia, Canada. Specimens were studied using a modified cellulose acetate peel technique using hydrofluoric acid. Diplopanax eydei Stockey, LePage et Pigg sp. nov. has fruits with endocarps up to 11 mm long and 10 mm in diameter that have a smooth stone surface, a single locule that is U-shaped in cross section, and a germination valve that extends nearly the full length of the fruit. An epicarp (exocarp C mesocarp) composed of thin-walled parenchymatous cells, 1.2‐1.5 mm thick, is preserved on one specimen. Remnants of an apical disc with possible perianth scars are seen in three specimens. The endocarp is composed of interlocking fibers with scattered resin ducts and vascular tissue that parallels the edges of the valve. Seed integuments consist of a single external layer of large cells with brown contents and an inner zone of two to four thin-walled cells of smaller diameter lacking contents. Numerous septate fungal hyphae are usually present in the integumentary layers. These fruits represent the first reported fossils of the genus Diplopanax Handel-Mazzetti, and the northernmost known mastixioids in North America. The fruits are compared to those of other living and fossil mastixioids including MastixicarpumChandler and add to our knowledge of the diversity and distribution of the North American mastixioids during the Tertiary.

Cytological and ultrastructural preservation in Eocene Metasequoia leaves from the Canadian High Arctic.

The ultrastructural examination by transmission electron microscopy of 45-million-year-old mummified leaves of Metasequoia extracted from the Upper Coal member of the Buchanan Lake Formation in Napartulik on Axel Heiberg Island revealed the preservation of intact chloroplasts and chloroplast components. Abundant tanniferous cell inclusions may indicate that the 3-mo period of constant daylight during the Artic summer induced high concentrations of tannins in the leaf tissues, which may have arrested microbial degradation of the litter. Quantified differences in the extent of chloroplast preservation through a vertical section of the lignite suggest that short-term shifts in the depositional environment took place, perhaps influencing the exposure of the leaf tissues to conditions that would either promote or inhibit decomposition.