Group Of Conifers Research Articles

Chemometric analysis of monoterpenes and sesquiterpenes of conifers.

Volatile organic compounds (VOCs) and essential oils of conifers are widely used in the pharmaceutical industry. This work aimed to analyze the VOCs of 30 conifer species representing the Pinaceae and Cupressaceae families. Samples were collected from arboreta in Hungary, and their chemical composition was determined by gas chromatography (SPME-GC/MS); then, chemometric analyses were performed using multivariate methods to identify characteristic VOCs of conifers. Here, we present results for monoterpene and sesquiterpene profiles of the examined conifer samples. The most abundant compounds detected were α-pinene, bornyl acetate, limonene, β-pinene, β-caryophyllene, β-myrcene, δ-3-carene, and β-phellandrene. The results showed that the following volatiles were characteristic of the conifer groups: sabinene (RRT=6.0) for the cupressoid group (which includes the Cupressaceae species), longifolene (RRT=15.0) and β-pinene (RRT=6.1) were characteristic of the pinoid group (including Picea, Pinus, and Pseudotsuga species), and camphene (RRT=5.5) and bornyl acetate (RRT=12.6) were characteristic of the abietoid group (including Abies, Cedrus, and Tsuga species). Our results on VOCs in the Pinaceae and Cupressaceae families contribute to the elucidation of biodiversity patterns of conifer species and, in addition, may support the industrial application of terpenes.

Male reproductive structures of Araucaria araucana and Wollemia nobilis (Araucariaceae, Coniferales) in light of conifer evolution

AbstractPollen cones of Araucaria araucana and Wollemia nobilis were investigated. They consist of hundreds of hyposporangiate microsporangiophores with numerous microsporangia, arranged in up to three abaxial rows. Convincing evidence was found that excludes the widely accepted sporophyll concept of coniferous microsporangiophores. It is shown that the units treated generally as sporophylls in fact represent a complex fusion product of numerous microsporangiophores (= synangia). The vasculature in the microsporangiophore may indicate that the hyposporangiate shape is derived from an ancestral perisporangiate condition. In particular, the bundle strands ending blindly in the tissue in distal parts of the scutellum can only be understood as belonging to aborted microsporangia. Transferring this concept to other conifers with hyposporangiate microsporangiophores a perisporangiate origin seems also highly likely for them. This is well supported by the fact that in usually hyposporangiate taxa occasionally perisporangiate microsporangiophores are developed. Thus, the gained results clearly indicate that each microsporangiophore corresponds to a lateral cone (= flower equivalent structure), and the entire pollen cone to a compound structure (= inflorescence equivalent structure). Thus, the evolutionary pathway of araucariaceous pollen cones fits well to the pseudanthial origin suggested previously for the male reproductive structures in other coniferous groups, e.g., Pinaceae or Taxaceae.

Gagates in Crimean middle jurassic sediments (Sudak): coal petrography, paleobotany, formation conditions

Background. The coal-bearing deposits of the Kopsel formation of the Bathonian-Callovian age of the Middle Jurassic near the city of Sudak (Crimea) are studied. The conducted lithological and mineralogical analysis of rocks, mainly sandstones and siltstones, with shell detritus, plant residues and coal lenses (gagates), made it possible to determine the coastal-marine and lagoon sedimentation conditions. The studied gagates are represented by structural vitrinite and belong to the humus group. Secondary minerals in coal seams and host rocks indicate the stage of early catagenesis. The botanical analysis revealed the coal-forming plants, belonging to a group of conifers of the araucaria family.Aim. To identify the facies-climatic and landscape conditions for the formation of gagates of the Kopsel formation, along with their composition, structure, and secondary changes. To demonstrate that the material composition of coals is the wood of gymnosperms, mainly conifers, rather than algal thalli.Materials and methods. The natural outcrops of the coal-bearing deposits of the Middle Jurassic of the Bathonian-Callovian stage of the Kopsel formation in the valley of the Kopsel River near the city of Sudak (Crimea) were studied. The lenses and interlayers of brown coal — gagate — present in these deposits were of particular interest. Gagate samples were studied both macroscopically (forms and occurrence conditions in the section) and microscopically (by coal petrography methods). To this end, double-sided polished sections were examined using a polarizing microscope and a Vega3 Tescan scanning microscope. The microanalysis of chemical elements was performed using an ULTM Max (GIN) microscope attachment. Paleobotanical studies of carbonified plant residues were carried out. The structure, texture and mineral composition of the rocks were studied in thin sections using a microscope. A mineralogical analysis was carried out using a D8 Advace X-ray diffractometer (gross composition in a powder diffractogram and composition of clays in a fraction of <0.001 mm) and a Vega3 Tescan (GIN) scanning microscope.Results. The comprehensive studies conducted in the new, unique location of coals in the Kopsel Formation of the Middle Jurassic (Bathonian-Callovian stage) in the valley of the Kopsel River determined the paleobotanical composition of coal-forming plants (with the predominance of conifers of the Araucariaceae type), the climatic and paleolandscape conditions for the formation of these coals on the northern outskirts of Tethys. The lithological and mineralogical features of rocks, mainly sandstones and siltstones, with shell detritus, plant residues and lenses of coals (gagates), make it possible to determine the facies conditions of sedimentation as coastal-marine and lagoonal, with fragments of avantdelta and proluvial, landslide deposits. The established secondary changes in the host rocks and the coals indicate the stage of early catagenesis, to which the stratum was subjected at the next stages of geological history.Conclusion. Peat accumulation and subsequent coal formation most likely occurred in shallow lagoons. The type of peat accumulation is paralytic, paragenetically related to the studied sediments. Post-sedimentation transformations of the rocks correspond to early catagenesis. These transformations were established by the presence of secondary calcite (by rock cracks and in the form of nodule formations), the abundance of authigenic gypsum, and the widespread replacement of pyrite framboids with iron oxide minerals. The interlayers of gagates have also undergone changes. In those places where organic matter is impregnated with carbonate solutions, the coal substance is exposed to heat, thus becoming optically opaque.

Niche conservatism and strong phylogenetic signals in climate, soil, and morphological variation of Neotropical firs (Abies, Pinaceae)

AbstractInterspecific trait divergence may reflect adaptation and reproductive isolation, particularly after the rapid differentiation that may follow the colonization of new environments. Although new lineages are generally expected to be morphologically and ecologically similar to their ancestors, environmental forces can also drive adaptive differentiation along specific phenotypic axes. We used climate niche models and comparative analyses based on a previously inferred phylogeny to examine the history of ecological and morphological divergence of Neotropical firs (Abies Mill., Pinaceae), a group of conifers that have recently colonized and diversified in the mountains of Mexico and northern Central America. We inferred past secondary contact zones by comparing current and past climate niche projections and looked for evidence of recent interspecific gene flow using genomic data. Neotropical firs have similar niches to each other and show a strong phylogenetic signal for most evaluated morphological traits. Analyses based on individual variables suggested a random walk model of differentiation. However, early adaptation to tropical conditions is inferred in the ancestor of the southernmost firs, as all modern southern taxa are differentiated climatically from Abies concolor, the northernmost species. In addition, observed autapomorphic traits for soil properties and the number of resin ducts in needles are consistent with possible species‐specific adaptations. Thus, a combination of nonadaptive and adaptive processes along different phenotypic axes, some related to the environment, likely operated after the southward migration of this plant lineage from North America and its subsequent radiation in the Neotropics.

New evidence of the architecture and affinity of fossil trees from the Jurassic Purbeck Forest of southern England

ABSTRACT We document the habit and affinity of the most complete Mesozoic Era tree to be excavated in the UK. The fossil was found in situ in a palaeosol of the Upper Jurassic Purbeck Group of southern England (Tithonian: ca. 150–145 million years). It comprises over 100 permineralized (silicified) pieces that represent a rooted stump and fallen trunk, together weighing more than two tonnes. This exceptional specimen was excavated in a manner that retained the original associations among its parts, providing a unique insight into the overall habit and mode of growth. A laser scanning approach was used to facilitate the investigation, producing the largest 3D reconstruction of a plant fossil. Anatomical details reveal that the wood belongs to the fossil-genus Agathoxylon. Despite an estimated growth age of more than 200 years, the tree was of modest size, not greatly exceeding 12 m in height. The main trunk bifurcated, developing into a decurrent, spreading crown. Its habit differed significantly from most modern arborescent conifers, which have pole-like central trunks and narrow, conical crowns, and from known growth forms in the Cheirolepidiaceae, an important extinct group of Mesozoic conifers. These findings extend our knowledge of the growth architecture of Jurassic conifers, which were prominent and diverse elements of seasonally arid, low to mid-latitude coastal communities during the Late Mesozoic.

The aboveground and belowground growth characteristics of juvenile conifers in the southwestern United States

AbstractJuvenile tree survival will play an important role in the persistence of coniferous forests and woodlands in the southwestern United States (SWUS). Vulnerability to climatic and environmental stress declines as trees grow, such that larger, more deeply rooted juveniles are less likely to experience mortality. It is unclear how juvenile conifers partition the aboveground and belowground components of early growth, if growth differs between species and ecosystem types, and what environmental factors influence juvenile carbon allocation above‐ or belowground. We developed a novel data set for four juvenile conifer groups (junipers, piñon pines, ponderosa pines, firs; 1121 juveniles sampled, 221 destructively) in three height classes (<150 mm, 150–300 mm, and 300+ mm), across 25 SWUS sites. We compared growth characteristics across groups and height classes and related differences to climatic and environmental factors. As tree height increased from <150 mm to 300+ mm, belowground growth increased, root:shoot ratio declined, and specific leaf area declined for all conifers except firs. Maximum rooting depth was shallower than previous estimates (<˜400 mm). Lower elevation juveniles were frequently located in sheltered microsites that provided high shading, whereas mid‐ and higher elevation juveniles were frequently unsheltered. Across all forest and woodland sites, herbaceous cover was positively correlated with aboveground growth. At study locations comprised of multiple sites, differences in aboveground growth were best explained by ecosystem type (piñon pine‐juniper woodland, ponderosa pine forest, mixed‐conifer forest) and local environmental variation. Our results indicate generally more belowground early growth and more aboveground later growth, but specific allocation patterns varied among ecosystem (greater proportional shoot growth at lower and mid‐elevations compared with higher elevations). Juvenile conifers had similar magnitudes of proportional growth across conifer groups, displaying limited capacity to acclimate growth to differences in climate that control ecosystem type. If juvenile conifers also do not acclimate physiologically to their environment, our findings suggest that local environmental variation will play a primary role in regulating forest and woodland persistence and modify the effects of climate change in the SWUS.

Sareomycetes: more diverse than meets the eye

Since its resurrection, the resinicolous discomycete genus Sarea has been accepted as containing two species, one with black apothecia and pycnidia, and one with orange. We investigate this hypothesis using three ribosomal (nuITS, nuLSU, mtSSU) regions from and morphological examination of 70 specimens collected primarily in Europe and North America. The results of our analyses support separation of the traditional Sarea difformis s.lat. and Sarea resinae s.lat. into two distinct genera, Sarea and Zythia. Sarea as circumscribed is shown to conservatively comprise three phylospecies, with one corresponding to Sarea difformis s.str. and two, morphologically indistinguishable, corresponding to the newly combined Sarea coeloplata. Zythia is provisionally maintained as monotypic, containing only a genetically and morphologically variable Z. resinae. The new genus Atrozythia is erected for the new species A. klamathica. Arthrographis lignicola is placed in this genus on molecular grounds, expanding the concept of Sareomycetes by inclusion of a previously unknown type of asexual morph. Dating analyses using additional marker regions indicate the emergence of the Sareomycetes was roughly concurrent with the diversification of the genus Pinus, suggesting that this group of fungi emerged to exploit the newly-available resinous ecological niche supplied by Pinus or another, extinct group of conifers. Our phylogeographic studies also permitted us to study the introductions of these fungi to areas where they are not native, including Antarctica, Cape Verde, and New Zealand and are consistent with historical hypotheses of introduction.

Using U-Net-Like Deep Convolutional Neural Networks for Precise Tree Recognition in Very High Resolution RGB (Red, Green, Blue) Satellite Images

Very high resolution satellite imageries provide an excellent foundation for precise mapping of plant communities and even single plants. We aim to perform individual tree recognition on the basis of very high resolution RGB (red, green, blue) satellite images using deep learning approaches for northern temperate mixed forests in the Primorsky Region of the Russian Far East. We used a pansharpened satellite RGB image by GeoEye-1 with a spatial resolution of 0.46 m/pixel, obtained in late April 2019. We parametrized the standard U-Net convolutional neural network (CNN) and trained it in manually delineated satellite images to solve the satellite image segmentation problem. For comparison purposes, we also applied standard pixel-based classification algorithms, such as random forest, k-nearest neighbor classifier, naive Bayes classifier, and quadratic discrimination. Pattern-specific features based on grey level co-occurrence matrices (GLCM) were computed to improve the recognition ability of standard machine learning methods. The U-Net-like CNN allowed us to obtain precise recognition of Mongolian poplar (Populus suaveolens Fisch. ex Loudon s.l.) and evergreen coniferous trees (Abies holophylla Maxim., Pinus koraiensis Siebold & Zucc.). We were able to distinguish species belonging to either poplar or coniferous groups but were unable to separate species within the same group (i.e. A. holophylla and P. koraiensis were not distinguishable). The accuracy of recognition was estimated by several metrics and exceeded values obtained for standard machine learning approaches. In contrast to pixel-based recognition algorithms, the U-Net-like CNN does not lead to an increase in false-positive decisions when facing green-colored objects that are similar to trees. By means of U-Net-like CNN, we obtained a mean accuracy score of up to 0.96 in our computational experiments. The U-Net-like CNN recognizes tree crowns not as a set of pixels with known RGB intensities but as spatial objects with a specific geometry and pattern. This CNN’s specific feature excludes misclassifications related to objects of similar colors as objects of interest. We highlight that utilization of satellite images obtained within the suitable phenological season is of high importance for successful tree recognition. The suitability of the phenological season is conceptualized as a group of conditions providing highlighting objects of interest over other components of vegetation cover. In our case, the use of satellite images captured in mid-spring allowed us to recognize evergreen fir and pine trees as the first class of objects (“conifers”) and poplars as the second class, which were in a leafless state among other deciduous tree species.

Early Cretaceous Brachyoxylon woods from Argentinean Patagonia and comments on the Cheirolepidiaceae distribution

We studied fossil woods from Matasiete and Castillo Formations (Aptian–Albian) for the first time. The woods, preserved in fluvial channel and floodplain deposits, have anatomy consistent with the fossil-genus Brachyoxylon Hollick and Jeffrey. Specimens from Castillo Formation have poorly distinct growth ring boundaries, exclusively uniseriate with a mixed arrangement intertracheary radial pitting, araucarioid cross-field pitting with 3–8 half-bordered pits with oblique aperture, and uniseriate rays. Specimens from Matasiete Formation are poorly preserved and only one could be assigned to Brachyoxylon with reservations. Brachyoxylon is a fossil-genus with a worldwide distribution and related to the fossil family Cheirolepidiaceae, a group of conifers that developed in various environments. However, our study suggests that this family would have prospered in locally semi-arid conditions.

The controversial nomenclature of the fossil plant namesCheirolepis,CheirolepidiumandHirmeriella(Cheirolepidaceae/Cheirolepidiaceae/Hirmeriellaceae)

AbstractA comprehensive nomenclatural analysis of the generic and suprageneric names used for an extinct conifer group, treated as a distinct family under the names Cheirolepidaceae, Cheirolepidiaceae or Hirmeriellaceae or a distinct order, Cheirolepidiales or Hirmeriellales, is presented. The fossil generic nameCheirolepisSchimp. (1870) is an illegitimate later homonym of the name of the extant genusCheirolepisBoiss. (1849; Asteraceae). It has been superfluously substituted with a new generic name,CheirolepidiumTakht. (1957). The authorship and place of valid publication ofCheirolepidiumis corrected based on newly discovered information. The correct generic name for these fossils isHirmeriellaHörhammer (1933), established originally for a cone consisting of persistent bract scales lacking seed scales, because it has priority over the generic nameCheirolepidiumTakht. All three fossil generic names were employed for the same fossil cone taxon, which represented different stages of maturity of the same seed cone. The inclusion of bothCheirolepisandCheirolepidiumunderHirmeriellawas proposed by Jung (1968) in his formal lectotypification of the type of the genus name,Cheirolepis muensteri(≡ Brachyphyllum muensteri), with a cone specimen that was cited in the protologues of the types of both genera,Cheirolepis muensteriandHirmeriella rhaetoliassica. The lectotypification ofCheirolepis muensteriandHirmeriella rhaetoliassicausing the same elements results in the three generic names being homotypic synonyms. As a consequence, the correct family name for the fossil conifer group is Hirmeriellaceae, to be proposed for conservation against Cheirolepidiaceae. Cheirolepidaceae is inadmissible being based on the illegitimate later homonymCheirolepisSchimp. and thus itself illegitimate.

The ecological-coenotic specters of the flora in the river Vyatka protected areas

The paper presents the results of a comparative ecological-coenotic analysis of 6 floras of the river Vyatka (Kirov Region, Russia). The floras of the studied areas are boreal and include rare and relic species of all-European importance. As for ecological structure the floras of the studied protected areas do not differ significantly and refer to 7 ecological-coenotic groups. Meadow and meadow-opening groups dominate in the revealed complex (28,48% to 41,84%). This may be caused by a systematic and strong anthropogenic impact on the protected areas. For example, trampling contributes to the increased invasion of meadow and meadow-edge species in forest ecosystems, where they take a significant part in the living ground cover, often acting as codominants with constant species of the grass-shrub layer of boreal forests. Less presented are wetland (13,61% to 27,15%), boreal (9,63% to 16,33%), nemoral (8,16% to 14,79%) and nitrophilous (8,16% to 13,33%) groups. The share of coniferous group varies from 4,44% to 7,10%. The oligotrophic group is presented by solitary species. The authors have also detected the correlation between the ecological-coenotic structure of the flora of the studied areas and the latitudinal location within the river basin.

Reconstructing Krassilovia mongolica supports recognition of a new and unusual group of Mesozoic conifers.

Previously unrecognized anatomical features of the cone scales of the enigmatic Early Cretaceous conifer Krassilovia mongolica include the presence of transversely oriented paracytic stomata, which is unusual for all other extinct and extant conifers. Identical stomata are present on co-occurring broad, linear, multiveined leaves assigned to Podozamites harrisii, providing evidence that K. mongolica and P. harrisii are the seed cones and leaves of the same extinct plant. Phylogenetic analyses of the relationships of the reconstructed Krassilovia plant place it in an informal clade that we name the Krassilovia Clade, which also includes Swedenborgia cryptomerioides–Podozamites schenkii, and Cycadocarpidium erdmanni–Podozamites schenkii. All three of these plants have linear leaves that are relatively broad compared to most living conifers, and that are also multiveined with transversely oriented paracytic stomata. We propose that these may be general features of the Krassilovia Clade. Paracytic stomata, and other features of this new group, recall features of extant and fossil Gnetales, raising questions about the phylogenetic homogeneity of the conifer clade similar to those raised by phylogenetic analyses of molecular data.

Early diversification and permeable species boundaries in the Mediterranean firs.

Inferring the evolutionary relationships of species and their boundaries is critical in order to understand patterns of diversification and their historical drivers. Despite Abies (Pinaceae) being the second most diverse group of conifers, the evolutionary history of Circum-Mediterranean firs (CMFs) remains under debate. We used restriction site-associated DNA sequencing (RAD-seq) on all proposed CMF taxa to investigate their phylogenetic relationships and taxonomic status. Based on thousands of genome-wide single nucleotide polymorphisms (SNPs), we present here the first formal test of species delimitation, and the first fully resolved, complete species tree for CMFs. We discovered that all previously recognized taxa in the Mediterranean should be treated as independent species, with the exception of Abies tazaotana and Abies marocana. An unexpectedly early pulse of speciation in the Oligocene-Miocene boundary is here documented for the group, pre-dating previous hypotheses by millions of years, revealing a complex evolutionary history encompassing both ancient and recent gene flow between distant lineages. Our phylogenomic results contribute to shed light on conifers' diversification. Our efforts to resolve the CMF phylogenetic relationships help refine their taxonomy and our knowledge of their evolution.

Propagation of Juniper Species by Plant Tissue Culture: A Mini-Review

The genus Juniperus (of the Cupressaceae family) is the second most prevalent group of conifers on Earth. Juniper species are widely dispersed in the Northern Hemisphere, in Europe and Asia, and in Africa and Central America. Juniper species are resistant to dry climates and can adapt to difficult environmental conditions. Most juniper species are important in both ecological and economic terms. However, today, many forests in which junipers occur are being reduced in size due to both natural causes (fires, for example) and human activity (uncontrolled exploitation of forests, etc.). Also, climate changes may have adversely affected the range of populations of different juniper species. For this reason, some juniper species are now categorized as rare or endangered, and require immediate protective action. Therefore, there is an urgent need to develop effective strategies for ex situ conservation, including reliable procedures for Juniperus sp. reproduction for future reintroduction and restoration programs. The conservation strategies used until now with traditional forestry techniques (seed propagation, rooted cuttings, grafting) have not been satisfactory in many cases. Thus, increasing attention is being paid to the possibilities offered by in vitro culture technology, which enables the conservation and mass clonal propagation of different coniferous tree species. In this mini-review, we summarize the current state of knowledge regarding the use of various methods of the propagation of selected Juniperus species, with a particular emphasis on in vitro culture techniques.

Respuesta climática de Abies guatemalensis Rehder en Ixtlán de Juárez, Oaxaca, México

En México existen especies arbóreas, específicamente, el grupo de las coníferas, las cuales permiten analizar y reconstruir las variaciones climáticas del pasado de una o varias regiones geográficas. El objetivo de este estudio fue determinar el potencial de respuesta dendrocronológica de Abies guatemalensis Rehder a la variabilidad climática en Ixtlán de Juárez, Oaxaca. Se desarrollaron cronologías de madera temprana, de madera tardía y de anillo total de 206 años (1810-2015). El análisis de correlación estacional señaló una relación directa entre la cronología RWI residual con la precipitación de invierno-primavera (r = 0.67, p < 0.01) y una relación indirecta con la temperatura máxima de primavera (r = -0.42, p < 0.01) del año actual de crecimiento. Mediante un modelo de regresión lineal se reconstruyó la precipitación acumulada de febrero a abril, de los últimos 136 años (1880-2015), el modelo explicó 44% de la variabilidad de los registros meteorológicos locales del período de calibración (1952-2010). Los períodos más secos ocurrieron en las décadas 1880, 1900, 1940, 1970, 1980, 1990 y 2000. El análisis espectral de la reconstrucción mostró una periodicidad cuasi-cíclica de 2.2 años y 3.8 años, indicando una asociación con el fenómeno ENSO. La sensibilidad de la especie a variaciones climáticas reflejadas en el grosor de los anillos de crecimiento, sugiere que A. guatemalensis tiene potencial para reconstrucciones hidroclimáticas, lo que permitirá extender en el tiempo los registros instrumentales para análisis más amplios de fluctuaciones en el clima y sus tendencias en esta región del país.

About the morphology and anatomy of pollen cones and the pollen presentation within the genus Fitzroya (Cupressaceae)

Fitzroya pollen cones show several features that are common for callitroid Cupressaceae including an uniaxial structure, the arrangement of microsporangiophores in trimerous whorls, and hyposporangiate microsporangiophores with several abaxial microsporangia, and a terminal scutellum. The strictly downward position of the pollen cones throughout their entire ontogeny distinguishes Fitzroya clearly from all other Cupressaceae s.str., but is similar to some basal Cupressaceae s.l. and other coniferous groups, including several Pinaceae and Taxaceae. The peltate scutellum which covers the microsporangia is unique among Cupressaceae and all other conifers. It seems to play an important role in protecting maturing microsporangia, and also within the anemophily syndrome. In Fitzroya the pollen is not removed from the cone directly from its place of origin, but from secondary deposits located in distal parts of the scutellum. A comparable pollen exposure is lacking in all other Cupressaceae but is common in other conifers, for example several Pinaceae and Podocarpaceae. Thus, pollen cones of Fitzroya comprise features which are the common family traits of Cupressaceae, but also features that are unique among this family, but common in other conifers. In addition, also features were found that are unique among all conifers.

A phylogenetic analysis of conifer diterpenoids and their carbon isotopes for chemotaxonomic applications

Plant-derived diterpenoids are commonly used as conifer-specific biomarkers and for chemotaxonomic assignment or confirmation. Numerous studies have reported on the utility of diterpenoids as chemotaxonomic indicators, but few have quantitatively analyzed diterpenoid concentrations, especially with respect to conifer phylogeny. In addition, the carbon isotope values (δ13C) of diterpenoids provide a means to track conifer-specific δ13C values, which is useful for tracking water availability and the carbon cycle. To expand on previous work, we measured diterpenoid concentrations and carbon isotopes of 43 conifer species, and Ginkgo biloba, collected at the University of California Botanical Garden at Berkeley. In this collection, all extant conifer families and almost two-thirds of extant genera are present, including many subtropical and Southern Hemisphere groups that were once common and widespread components of fossil assemblages. Overall, we found diterpenoid concentrations were highly variable among species and families. Despite this variability, there is coarse family-level phylogenetic structuring with the lowest concentrations in Pinaceae. When diterpenoid concentrations are fitted to a model of trait evolution (Brownian motion), we however find that there is no phylogenetic signal. In contrast, when terpenoids are analyzed by the proportion of diterpenoid compound structure classes (abietanes, labdanes, pimaranes, tetracyclics, and totarols/sempervirol), there was significant phylogenic signal for the abietane and tetracyclic structures. Diterpenoid biosynthetic carbon isotope fractionation, as expressed between diterpenoids and leaf tissue (εditerpenoid), also contained a phylogenetic signal, as well as the broad phylogenetic structuring observed in total diterpenoid concentrations. Overall, these results indicate that the Pinaceae is unique among conifer clades with respect to terpenoid structure classes, concentrations and εditerpenoid. When diterpenoids are applied to taxonomic assignment of fossils, it would be useful to combine several traits (concentration, proportion, and εditerpenoid). In this context, it should be possible to broadly distinguish three major conifer groups: Cupressaceae, Podocarpaceae and Pinaceae. However, based on these results, we recommend against assuming that closely related species have similar diterpenoid compositions.

De novo assembly of English yew (Taxus baccata) transcriptome and its applications for intra- and inter-specific analyses.

We provide novel genomic resources for Taxus baccata in the form of a reference transcriptome, SSR and SNP markers, and orthologous single-copy genes, useful for phylogenomic and population genomic applications. English yew (T. baccata) is the only European representative of the Taxaceae family, a conifer group originated in the Jurassic period. The wide extent of environmental heterogeneity within the species' range, together with its long presence in Europe, make English yew an ideal species to investigate adaptive evolution in conifers. To enlarge the genomic resources available for this species, we used Illumina short read sequencing followed by de novo assembly to build the transcriptome of English yew. In addition to a fully annotated transcriptome as well as large sets of new potential SSR and SNP markers for T. baccata, we provide a data set of orthologous single-copy genes across three Taxus species using Picea sitchensis as outgroup, and discuss ortholog uses and limitations for phylogenomic and population genomic applications.

Interspecific variation in growth responses to tree size, competition and climate of western Canadian boreal mixed forests

Tree growth of boreal forest plays an important role on global carbon (C) cycle, while tree growth in the western Canadian boreal mixed forests has been predicted to be negatively affected by regional drought. Individual tree growth can be controlled by many factors, such as competition, climate, tree size and age. However, information about contributions of different factors to tree growth is still limited in this region. In order to address this uncertainty, tree rings of two dominant tree species, trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench.) Voss), were sampled from boreal mixed forest stands distributed across Alberta, Canada. Tree growth rates over different time intervals (10years interval, 1998–2007; 20years interval, 1988–2007; 30years interval, 1978–2007) were calculated to study the effects of different factors (tree size, competition, climate, and age) on tree growth. Results indicated that tree growth of two species were both primarily affected by competition or tree size, while climatic indices showed less effects on tree growth. Growth of trembling aspen was significantly affected by inter- and intraspecific competition, while growth of white spruce was primarily influenced by tree size, followed by competition. Positive relationship was found between growth of white spruce and competition index of coniferous group, suggesting an intraspecific mutualism mechanism within coniferous group. Our results further suggested that competition driven succession was the primary process of forest composition shift in the western Canadian boreal mixed forest. Although drought stress increased tree mortality, decline of stem density under climate change released competition stress of surviving trees, which in turn sustained growth of surviving trees. Therefore, climatic indices showed fewer effects on growth of dominant tree species compared to other factors in our study.

Layering in the Rocky Mountain treeline ecotone: clonal conifer groups’ distribution, structure, and functional role

Layering plays a major role in treeline stability. Growth ring pattern of clonal groups reflects both an individualistic and an only temporally common response to the harsh treeline environment. Clonal groups are common to alpine and polar treelines. Distribution, shape, architecture, and development of clonal Picea engelmannii and Abies lasiocarpa in an extremely windy Rocky Mountain treeline ecotone are considered. Clonal groups prevail (>70% of all tree groups). Most of them consist of A. lasiocarpa (65%). Number, growth form, and damage were documented along transects and field routes. Age structure and development of the clonal groups were assessed using increment cores and stem disks. The groups usually consisted of different clonal series with several clonal members in each. On wind-swept terrain, clonal groups exhibit wedge-like, hedge-like, or mat-like habit. One clonal A. lasiocarpa group was studied in detail and it serves as an example showing formation, architecture, and internal growth pattern of clonal series. The clone members in the clone series exhibited an individualistic growth pattern. Wind-control of growth occasionally overruled the often ‘chaotic’ internal group growth pattern. The effect of prevailing winds, however, temporally overlapped with a ‘force’ directed from the center of the group margin (e.g., competition for light, high stem density), as reflected in recurrent change of eccentricity within the clonal trunks. Clonal groups may be of major importance in treeline dynamics.