The oldest Pinus and its preservation by fire

Pinus (Pinaceae) is a diverse conifer genus that dominates Northern Hemisphere forests today and is noteworthy for its fire-adapted traits. Here we describe the oldest known fossils attributable to the genus from the Lower Cretaceous (Valanginian, ca. 133–140 Ma) part of the Chaswood Formation of Nova Scotia, Canada. Pinus mundayi sp. nov. comprises charred long-shoots, which show a constellation of derived characters including (1) axial resin ducts with thin walled epithelial cells in the secondary xylem and phloem, (2) fenestriform or pinoid cross-field pits, and (3) helically arranged short-shoots that pass through growth ring boundaries before distally diverging into two separate needle bases. The fossils, which are interpreted as remains of an evergreen two-needle pine, provide a new constraint on timetrees of Pinaceae evolution. Their preservation as charcoal and the occurrence of resin ducts, which produce flammable terpenes in modern pines, show that Pinus has co-occurred with fire since its Mesozoic origin

Evidence for coal forest refugia in the seasonally dry Pennsylvanian tropical lowlands of the Illinois Basin, USA

The Moscovian plant macroflora at Cottage Grove southeastern Illinois, USA, is a key example of Pennsylvanian (323–299 Million years ago) dryland vegetation. There is currently no palynological data from the same stratigraphic horizons as the plant macrofossils, leaves and other vegetative and reproductive structures, at this locality. Consequently, reconstructions of the standing vegetation at Cottage Grove from these sediments lack the complementary information and a more regional perspective that can be provided by sporomorphs (prepollen, pollen, megaspores and spores). In order to provide this, we have analysed the composition of fossil sporomorph assemblages in two rock samples taken from macrofossil-bearing inter-coal shale at Cottage Grove. Our palynological data differ considerably in composition and in the dominance-diversity profile from the macrofossil vegetation at this locality. Walchian conifers and pteridosperms are common elements in the macroflora, but are absent in the sporomorph assemblages. Reversely, the sporomorph assemblages at Cottage Grove comprise 17 spore taxa (∼16% and ∼63% of the total assemblages) that are known from the lycopsid orders Isoetales, Lepidodendrales and Selaginallales, while Cottage Grove’s macrofloral record fails to capture evidence of a considerable population of coal forest lycopsids. We interpret our results as evidence that the Pennsylvanian dryland glacial landscape at Cottage Grove included fragmented populations of wetland plants living in refugia

La multiplication de matériel de plantation de qualité pour améliorer l'état sanitaire et la productivité des cultures : pratiques clefs pour les bananiers et les bananiers plantain. Guide illustré

Available in English, French, Spanish and Arabic, on line and on CD-ROM, this illustrated guide summarizes the key practices for producing clean planting material of banana with a high yield potential for smallholders, depending on the pests and diseases which are present. The guide is also designed to contribute to better planning of the propagation of planting material for rural development and disaster relief projects. (Résumé d'auteur

A Marine Incursion in the Lower Pennsylvanian Tynemouth Creek Formation, Canada:Implications for Paleogeography, Stratigraphy and Paleoecology

We document the occurrence of a marine bed, and its associated biota, in the Lower Pennsylvanian (Langsettian) Tynemouth Creek Formation of New Brunswick, and discuss its implications for paleogeography, stratigraphy, and paleoecology. This is only the second marine interval found in the entire Pennsylvanian fill of the Maritimes Basin of Canada, the other being recently found in the broadly same-age Joggins Formation of Nova Scotia. Evidence for the new marine transgression comprises an echinoderm-rich limestone that infills irregularities on a vertic paleosol surface within the distal facies of a syntectonic fluvial megafan formed under a seasonally dry tropical climate. Gray, platy ostracod-rich shales and wave-rippled sandstone beds that directly overlie the marine limestone contain trace fossils characteristic of the Mermia Ichnofacies, upright woody trees, and adpressed megafloras. This association represents bay-fills fringed by freshwater coastal forests dominated by pteridosperms, cordaites, and other enigmatic plants traditionally attributed to dryland/upland habitats. The fossil site demonstrates that marine transgressions extended farther into the interior of Pangea than has previously been documented, and may allow correlation of the Tynemouth Creek and Joggins Formations with broadly coeval European successions near the level of the Gastrioceras subcrenatum and G. listeri marine bands. It also helps explain the close similarity of faunas between the Maritimes Basin and other paleotropical basins, if transgressions facilitated migration of marine taxa into the continental interior

Climate–vegetation models bring fossil forests back to life

Globally widespread forests first arose in the Pennsylvanian subperiod, some 300 to 320 Ma, populated by bizarre tree-sized club mosses, ferns, sphenophytes, and gymnosperms (1). At this time, most of Earth’s landmasses were fused together as Pangaea, gripped by the late Paleozoic ice age, and subject to glacial–interglacial cycles (2). The compacted remains of the forests that densely covered this partially frozen supercontinent are widely preserved, and in the best-explored tropical realm form economic coal measures (3). Knowledge of the so-called Pennsylvanian coal forests has been literally mined from Earth’s surface through 200 y of hard labor in the coalfields of Appalachia, the Ruhr, and South Wales, among many other places (3). These hard-won fossil discoveries reveal that primeval vegetation choked almost every conceivable terrestrial environment from boggy deltas (3) to rugged mountain terrains (4). Especially tantalizing is the localized preservation of whole forested landscapes, allowing scientists to walk for miles through the coalified stands of upright fossil trees (5). Yet, despite being entombed with such remarkable fidelity, Pennsylvanian forests remain deeply mysterious ecosystems, lacking even remotely close living relatives for comparison. In PNAS, Matthaeus et al. (6) develop sophisticated vegetation–climate models that elegantly fuse traditional fossil data with fundamental plant physiology to bring these long-dead forests back to life. Quite unexpectedly, their wide-ranging findings identify frost tolerance as a key factor in controlling Pennsylvanian forest dynamics and distribution, with episodic frost dieback disturbing cycles of runoff, erosion, and weathering at a global scale. They further hypothesize that enhanced frost tolerance, which arose in early conifers, may have simultaneously conferred drought adaptation, paving the way for conifer dominance in the hot and arid Mesozoic that followed the cool Paleozoic

Anatomically-preserved cordaitalean trees from Lower Pennsylvanian (Langsettian) dryland alluvial-plain deposits at Joggins, Nova Scotia

Recent discoveries at Joggins, Nova Scotia have altered our understanding of the Pennsylvanian tropical biome. Of particular significance has been the recognition of seasonal dryland ecosystems, compositionally distinct from the peat-forming wetland rainforests. Here I describe two anatomically-preserved fossil plant specimens from dryland alluvial plain facies. The first specimen, Mesoxylon cf. sutcliffi i, is previously unknown from Joggins. It is a septate cordaitalean axis with mesarch leaf traces and a non-sympodial vasculature. Where found as isolated blocks, the secondary xylem of this plant has previously been classified as Dadoxylon recentium. The axis exhibits subtle growth interruptions suggestive of tropical rainfall seasonality, while associated traumatic zones may record fire-damage. The second specimen is a Dadoxylon stump rooted within well-drained floodbasin soils. It confirms earlier conjecture, based on parautochthonous assemblages, that cordaitalean trees grew in inter-channel areas. Together these new specimens improve our knowledge of the composition and ecology of seasonal dryland vegetation at Joggins. RÉSUMÉ Des découvertes récentes à Joggins (Nouvelle-Écosse), ont modifié notre compréhension du biome tropical pennsylvanien. La reconnaissance d'écosystèmes de milieux arides saisonniers aux compositions distinctes des forêts tropicales humides ayant formé des tourbières, s'avère particulièrement importante. Je décris aux présentes deux spécimens préservés de plantes fossiles anatomiquement provenant du faciès d'une plaine alluviale de milieu aride. Le premier spécimen, un Mesoxylon cf. sutcliffi i, était auparavant inconnu à Joggins. Il s'agit d'un axe cordaitaléen cloisonné comportant des cicatrices foliaires à arc moyen et une vasculature non sympodiale. Lors de sa découverte sous forme de blocs isolés, on avait précédemment classifié le xylème secondaire de cette plante en tant que Dadoxylon recentium L'axe présente des interruptions de croissance subtiles évoquant des chutes de pluie tropicales saisonnières, tandis que les cernes traumatiques associés pourraient témoigner de dommages causés par le feu. Le second spécimen est une souche de Dadoxylon qui plongeait ses racines à l'intérieur des sols d'un bassin de crue bien drainé. Il confirme une conjecture antérieure, basée sur des assemblages parautochtones, supposant que les arbres cordaitaléens aient poussé dans des secteurs situés entre des chenaux. Ces deux nouveaux spécimens améliorent notre connaissance de la composition et de l'écologie de la végétation saisonnière des milieux arides à Joggins. [Traduit par la rédaction.

Earliest history of coal mining and grindstone quarrying at Joggins, Nova Scotia, and its implications for the meaning of the place name “Joggins”

The rich history of coal mining and grindstone quarrying at Joggins, Nova Scotia, prior to Lyell’s visit in 1842 is less well known than its subsequent history. Franquelin first observed coal there in 1686, and within little more than a decade Acadian coal mines had sprung up at the Coal Cliffs. Following the British acquisition of Nova Scotia in 1713, the coal mines attracted Captain Belcher and other New England traders, who loaded their ships with coal for sale in Boston. In 1731, eager to impose duty on this unregulated trade, the Nova Scotia Council sponsored a British coal mine at Joggins operated by Major Cope. Unable to safely load ships at the Coal Cliffs, Cope constructed a wharf and coal depot at Gran’choggin (present-day Downing Cove), seven miles to the north of the mine. It was by association with this depot that the Coal Cliffs later became known as Joggins. Cope’s coal mine survived less than eighteen months before the Mi’kmaq, aided and abetted by Acadians, destroyed the site in 1732. Following this episode, Acadians worked the Joggins coal mines until they fell under the control of British forces engaged in the Seven Years War in 1756. Subsequently, the Lords of Trade suppressed coal mining at Joggins, fearing it would harm British imports, and full-scale operations did not recommence until 1847. During this lull, the grindstone industry boomed. Beginning sometime before 1764, the principal stone quarries operated at Lower Cove, where the famous Blue-Grit was cut. Grindstone quarries were also worked on the Maringouin Peninsula and the two opposing sides of Chignecto Bay became known as the North and South Joggins. RÉSUMÉ On connaît moins bien le riche passé de l’extraction du charbon et de la pierre meulière à Joggins, Nouvelle‑Écosse, avant la visite de Lyell en 1842, que son passé subséquent. Franquelin y avait observé du charbon pour la première fois en 1686 et en l’espace d’un peu plus d’une décennie, plusieurs mines de charbon acadiennes étaient apparues à Coal Cliffs. À la suite de l’acquisition de la Nouvelle‑Écosse par les Britanniques en 1713, les mines de charbon ont attiré le capitaine Belcher et d’autres commerçants de la Nouvelle‑Angleterre qui chargeaient leurs vaisseaux de charbon pour le vendre à Boston. En 1731, impatient d’imposer des droits sur ce commerce non réglementé, le Conseil de la Nouvelle‑Écosse a parrainé l’exploitation à Joggins d’une mine de charbon britannique exploitée par le major Cope. Incapable de charger de façon sécuritaire les navires à Coal Cliffs, Cope construisit un quai et un dépôt de charbon à Gran’choggin (anse Downing actuelle), à sept milles au nord de la mine. L’association à ce dépôt a plus tard conféré à Coal Cliffs le nom de Joggins. La mine de charbon de Cope a subsisté moins de 18 mois jusqu’à ce que les Micmacs, aidés et soutenus par les Acadiens, détruisirent l’emplacement en 1732. Après cet épisode, les Acadiens ont exploité les mines de charbon de Joggins jusqu’à ce qu’elles tombent sous le contrôle des forces britanniques engagées dans la guerre de Sept Ans en 1756. Les lords du commerce ont subséquemment supprimé l’extraction du charbon à Joggins, par crainte qu’elle fasse tort aux importations britanniques, et l’exploitation à grande échelle n’a pas recommencé avant 1847. Pendant cette période d’accalmie, l’industrie de la pierre meulière a connu un essor notable. Les principales carrières de pierre ont commencé leurs activités dans les années ayant précédé 1764 à Lower Cove, où l’on extrayait le fameux grès dur bleu. Des carrières de pierre meule ont également été exploitées sur la péninsule Maringouin et les deux rives opposées de la baie Chignectou devinrent connues sous les noms de North et South Joggins

New Brunswick and Nova Scotia: the First Geological Field Trip by a North American College

The first known geological excursion by a North American college was conducted in 1835. Twenty staff and students belonging to Williams College — a liberal arts college in Massachusetts, USA — explored the geology bordering the Bay of Fundy in northeast Maine, New Brunswick and Nova Scotia. Led by two young professors of natural history, Ebenezer Emmons and Albert Hopkins, the party made extensive observations around Pasammaquoddy Bay, Saint John, Parrsboro, and Windsor, as well as more widely through the Minas and Cumberland basins. Although partly following in the footsteps of two pioneering Bostonians, Charles Jackson and Francis Alger, who had reconnoitred the region in the late 1820s, the Williams College party nevertheless made several original observations. One of most important was a study of the anatomy and paleoclimatic significance of permineralized plants from Joggins and Grindstone Island undertaken by Emmons. This was only the second study of its kind worldwide and later inspired William Dawson to do similar work. Largely overlooked by historians of geology, the Williams College expedition, which comprised a four-week voyage of about 1800 km, illustrates well the challenges and opportunities of geological field work in the early Nineteenth Century. RÉSUMÉ La première excursion géologique connue d’un collège nord‑américain a été réalisée en 1835. Vingt membres du personnel et étudiants du Collège Williams — collège d’arts libéraux du Massachusetts, Etats-Unis — ont exploré la géologie des bords de la baie de Fundy dans le nord‑est du Maine, au Nouveau‑Brunswick et en Nouvelle‑Écosse. Le groupe dirigé par deux jeunes professeurs d’histoire naturelle, Ebenezer Emmons et Albert Hopkins, a effectué de nombreuses observations dans les environs de la baie de Passamaquoddy, de Saint‑Jean, de Parrsboro et de Windsor, ainsi que dans des secteurs plus étendus à l’intérieur des bassins Minas et Cumberland. Même si le groupe du Collège Williams a en partie suivi les pas de deux pionniers de Boston, Charles Jackson et Francis Alger, qui avaient effectué une reconnaissance de la région vers la fin des années 1820, il a néanmoins fait plusieurs observations originales. L’une des plus importantes a été l’étude de l’anatomie et de l’importance paléoclimatique des végétaux minéralisés de Joggins et de l’île Grindstone réalisée par Emmons. Il s’agissait seulement de la deuxième étude du genre à l’échelle mondiale; elle a ultérieurement inspiré Williams Dawson à exécuter des travaux similaires. Largement négligée par les historiens de géologie, l’expédition du Collège Williams, qui a comporté un voyage de quatre semaines d’environ 1 800 kilomètres, illustre bien les défis et les possibilités qui s’offraient dans le domaine des travaux géologiques sur le terrain au début du 19e siècle. [Traduit par la redaction

A Cordaixylon axis from well-drained alluvial plain facies in the Lower Pennsylvanian Joggins Formation of Nova Scotia

Plant remains showing preservation of cellular anatomy are rare in the Lower Pennsylvanian Joggins Formation of Nova Scotia. Here I report an anatomically preserved cordaitalean axis that shows endarch maturation and a sympodial vascular architecture. The specimen belongs to the morphogenus Cordaixylon, but in the absence of extraxylary tissue or attached fertile material, it cannot be assigned to a species. Together with a previously reported Mesoxylon axis with mesarch and non-sympodial vasculature, the new discovery demonstrates the existence of both major organizational types of cordaitalean at this locality. Previous reports have identified Cordaixylon as a plant that preferred peat mire environments. In this paper, the morphogenus is recorded from well-drained alluvial plain facies, thus extending knowledge of its ecological range. Résumé Les vestiges de plantes présentant une préservation de l’anatomie cellulaire sont rares à l’intérieur de la Formation du Pennsylvanien inférieur de Joggins, en Nouvelle-Écosse. Je fais part dans les présentes d’un axe de cordaitaléen natomiquement préservé qui affiche une maturation circulaire à partir de l’intérieur et une architecture vasculaire sympodiale. Le spécimen fait partie du morphogenre Cordaixylon, mais en l’absence de tissu extraxylaire ou de matière fertile y étant fixée, on ne peut pas le rattacher à une espèce donnée. La nouvelle découverte, conjuguée à un axe de Mesoxylon précédemment signalé qui comportait une vasculature non sympodiale à éléments en spirale internes, révèle l’existence des deux principaux types structuraux de cordaitaléens à cet emplacement. Des rapports antérieurs avaient défini le Cordaixylon en tant que plante préférant les environnements à bourbiers de tourbe. Le présent document fait état de l’observation du morphogenre d’un faciès de plaine alluviale bien drainée, ce qui étend notre connaissance de son aire de distribution écologique

A process-based model of conifer forest structure and function with special emphasis on leaf lifespan

We describe the University of Sheffield Conifer Model (USCM), a process-based approach for simulating conifer forest carbon, nitrogen, and water fluxes by up-scaling widely applicable relationships between leaf lifespan and function. The USCM is designed to predict and analyze the biogeochemistry and biophysics of conifer forests that dominated the ice-free high-latitude regions under the high pCO2 “greenhouse” world 290–50 Myr ago. It will be of use in future research investigating controls on the contrasting distribution of ancient evergreen and deciduous forests between hemispheres, and their differential feedbacks on polar climate through the exchange of energy and materials with the atmosphere. Emphasis is placed on leaf lifespan because this trait can be determined from the anatomical characteristics of fossil conifer woods and influences a range of ecosystem processes. Extensive testing of simulated net primary production and partitioning, leaf area index, evapotranspiration, nitrogen uptake, and land surface energy partitioning showed close agreement with observations from sites across a wide climatic gradient. This indicates the generic utility of our model, and adequate representation of the key processes involved in forest function using only information on leaf lifespan, climate, and soils