Woody Axes Research Articles

Life on the Edge: A Powerful Tsunami Overwhelmed Indian Ocean Mangroves One Millennium Ago

In this paper, we demonstrate how subfossil mangrove wood can be used to elucidate the timing of past tsunami events. Although tsunamis generated by submarine earthquakes along the Makran subduction zone in the Arabian Sea are not unusual, rigorous age documentation is generally lacking. The best known is the only instrument-recorded tsunami, which affected the coastlines of Iran, Pakistan, India, and Oman in November 1945. Eyewitness accounts of the effect along the Oman coastline assert that this tsunami was not destructive. However, a 25-cm-thick shell layer in the lagoon adjacent to the city of Sur was attributed to the 1945 tsunami, although dating of the shell deposit proved difficult, and the radiocarbon dates of mollusk shells were regarded as unreliable. Here, we reinterpret the age of this tsunamigenic layer based on the new discovery of parallel-oriented woody axes in the sedimentological context of the tsunami shell layer in the Sur lagoon. The woody axes were analyzed anatomically and identified as pertaining to the gray mangrove Avicennia. Radiocarbon dating of the wood (905–722 cal BP), along with sedimentological investigations, suggests that the deposition of the woody axes should be attributed to an older tsunami event that occurred ca. 1000 years ago, which has been documented at other locations along the Arabian Sea coastline. From this, we conclude that mangroves grew in this lagoon at that time. Very little is known about ancient mangrove distribution in this region and, so far, no records have been provided for this time window at this site. We also deduce that the tsunami event that occurred one millennium ago must have been substantially more severe than the one in 1945. More accurate dating of tsunamigenic events will aid in calculating the recurrence intervals and magnitude of tsunamis generated along the Makran subduction zone.

Leaf deciduousness and flowering of woody caatinga species

We determined the distribution (FDI), duration (FDU), and peak (FPE) of flowering in woody deciduous (DE) and evergreen (EV) species of the Caatinga with available data in the literature. Possible relations were established between leaf persistence and reproductive phenology throughout the year. The FDI indicated the relative number of species bearing flowers in each month, and the FDU denoted the number of months each species showed flowers. We defined the FPE as the four consecutive months with the highest number of species in flower. DE and EV did not show significant differences in FDI and FDU, probably due to the inability to sustain reproductive and vegetative annexes of woody axes simultaneously during the dry period. Some DE species showed flowering during the dry period in a crown free of leaves. EV flowering occurred outside the dry period. Flowering during the dry season in DE may happen due to water accumulated inside the plant body. FPE in EV during the transition between dry-rainy periods may indicate the ability to capture the first rain from all the plant body surface, covering the hydric demand of full foliage and folded reproductive buds anticipating the flowering in DE. This resulted in different values of FPE between DE and EV.

A network model for determining decomposition, topology, and properties of the woody crown

The acquisition of resources and airspace of woody crown occur by way of axes supporting annexes. Regardless of age, size, or branching system (monopodial or sympodial), the woody crown shows branched leafy axes implementing an aerial network. We propose here to represent the woody crown through a network comprised of two components, the segments of woody axes named connectors (CO) delimited by nodes (NO) as the branching regions. CO may link NO of different categories (regular, initial, final, and emission) as defined by the relative position of the NO in a crown and how many CO the NO has. The woody crown network (WCN) is similar to a random network with the probability of NO having some CO following an exponential decay. The absence of loops and real hubs weakened the robustness of WCN against failure or attacks on NO. The quantities of NO and CO and the proportions between them were the features of decomposition, and the distances measured in some CO between types of NO captured the topological characteristics of WCN. By combining decomposition and topology, we disclosed some properties of WCN, such as navigability, vulnerability, symmetry, and complexity. Navigability and complexity increased, while vulnerability and symmetry decreased exponentially as the size (ΣNO) of WCN enlarged. The behavior of properties as a function of ΣNO exposed some limits to mitigate the inherent hydraulic resistance during WCN development. Decomposition, topology, and properties of WCN in trees of Cerrado vegetation were interrelated to other crown traits revealing the strategies for acquiring airspace.

A Tournaisian (earliest Carboniferous) conglomerate-preserved non-marine faunal assemblage and its environmental and sedimentological context.

A conglomerate bed from the Tournaisian Ballagan Formation of Scotland preserves a rich array of vertebrate and other nonmarine fossils providing an insight into the wider ecosystem and paleoenvironment that existed during this pivotal stage of Earth history. It challenges hypotheses of a long-lasting post-extinction trough following the end-Devonian extinction event. The fauna recovered includes a wide size range of tetrapods, rhizodonts, and dipnoans, from tiny juveniles or small-bodied taxa up to large adults, and more than one taxon of each group is likely. Some fauna, such as actinopterygians and chondrichthyans, are rare as macrofauna but are better represented in the microfossil assemblage. The fauna provides evidence of the largest Carboniferous lungfish ever found. The specimens are preserved in a localized, poorly-sorted conglomerate which was deposited in the deepest part of a river channel, the youngest of a group of channels. In addition to the fossils (micro- and macro-), the conglomerate includes locally-derived clasts of paleosols and other distinctive elements of the surrounding floodplains. Charcoal fragments represent small woody axes and possible larger trunk tissue from arborescent pteridosperms. Preservation of the fossils indicates some aerial exposure prior to transport, with abrasion from rolling. The findings presented here contrast with other published trends in vertebrate size that are used to interpret a reduction in maximum sizes during the Tournaisian. The richness of the fauna runs counter to the assumption of a depauperate nonmarine fauna following the end-Devonian Hangenberg event, and charcoal content highlights the occurrence of fire, with the requisite levels of atmospheric oxygen during that stage.

Quantitative Application of the Whole-Plant Concept to the Messinian – Piacenzian Flora of Italy

The analysis of a taxonomical database containing Italian pollen and macrofossil records of the Messinian - Piacenzian time interval allowed us to evaluate the possible assemblage of different parts within a Whole-Plant Concept. The fossil plant parts that we deemed more significant were: “herbarium-like” specimens, foliage, female and male reproductive organs and stem parts (mainly woody axes). When it has been possible, we recognized these different parts as putative products of a single ancient plant species. Then we operated a random selection of 100 taxonomical entities (potential whole-plant taxa, indicated by the progressive numbers WP001, WP002, etc.) and we analysed their fossil record in order to quantify the proportion of ancient plants represented by one, two or more different parts in the fossil record of the studied area and time slice. Our quantitative analysis showed that 63 % of the potential whole-plant taxa are represented by a single type of plant part, 23 % are represented by two plant parts, and 14 % by three or more different parts. A few taxa were selected as examples to show in detail the implications of applying the Whole-Plant Concept; this involved a taxonomic discussion of Actinidia, Ailanthus, Engelhardia, Eucommia, Glyptostrobus and Taxodium.

C depletion and tree dieback in young peach trees: a possible consequence of N shortage?

Bud burst disruption, carbon depletion and tree dieback in spring were experimentally linked to N shortage the previous autumn. Dieback occurred despite tree N concentrations were compatible with plant survival: their N stores being blocked in the roots and woody axes. Tree dieback is generally linked to hydraulic failure or carbon (C) starvation but seldom to poor nitrogen (N) resources. We provide here an experimental evidence linking autumn N shortage, C depletion and tree dieback in spring. Young peach trees were either N deprived or fertilised in autumn, and then fed in excess in spring. Spring supplies were 15N-labelled. The effects of the deprivation on tree development, N uptake and C status were then assessed by coupling in situ measurements of shoot development with organ biochemical and isotopic determinations. All deprived trees died within 3 months after burst. Bud burst was severely disrupted, and vegetative growth limited to the expansion of a few leaves. The dead trees absorbed between 39 and 117 mg 15N in spring, and their roots and axes contained 758 mg more nitrogen than the fertilised trees, suggesting that they did not mobilise their N reserves in spring. They also had lower non-structural carbohydrate concentrations ( 15.4 % DW), which were below the threshold accepted for plant survival. Two possible causes of total non-structural carbon (or TNC) depletion are discussed: insufficient storage due to advanced leaf senescence or increase in the C costs regarding winter embolism recovery.

The remarkable congruence of New and Old World savanna origins.

The remarkable congruence of New and Old World savanna origins.

The earliest wood and its hydraulic properties documented inc. 407-million-year-old fossils using synchrotron microtomography

We document xylem structure and hydraulic properties in the earliest woody plant Armoricaphyton chateaupannense gen. nov. & sp. nov. based on c. 407-million-year-old fossils from the Armorican Massif, western France. The plant was small, and the woody axes were narrow and permineralized in pyrite (FeS2). We used standard palaeobotanical methods and employed propagation phase contrast X-ray synchrotron microtomography (PPC-SRμCT) to create three-dimensional images of the wood and to evaluate its properties. The xylem comprised tracheids and rays, which developed from a cambium. Tracheids possessed an early extinct type of scalariform bordered pitting known as P-type. Our observations indicate that wood evolved initially in plants of small stature that were members of Euphyllophytina, a clade that includes living seed plants, horsetails and ferns. Hydraulic properties were calculated from measurements taken from the PPC-SRμCT images. The specific hydraulic conductivity of the xylem area was calculated as 8.7 kg m−1 s−1 and the mean cell thickness-to-span ratio (t/b)2 of tracheids was 0.0372. The results show that the wood was suited to high conductive performance with low mechanical resistance to hydraulic tension. We argue that axis rigidity in the earliest woody plants initially evolved through the development of low-density woods

Structure and relationships of the Jurassic conifer seed cone Hughmillerites juddii gen. et comb. nov.: Implications for the origin and evolution of Cupressaceae

Anatomically preserved Jurassic conifer seed cones originally described as Conites juddi Seward and Bancroft are reinvestigated and assigned to Hughmillerites juddii gen. et comb. nov. using the original specimens and new material from the type locality. This allows for a more thorough characterization of seed cone structure, for systematic placement of the species, and for establishing homologies of cupressaceous bract/scale complexes. Incomplete cones range 2.2–3.6 cm in diameter and 3.0–4.3 cm long, and have distinctly woody axes bearing helically arranged bract/scale complexes with a thickened bract tip. Mature complexes display three inverted seeds attached to the adaxial surface immediately proximal to three free ovuliferous scale tips. In each bract/scale complex there is a single large resin canal abaxial to the vascular bundle and three or more smaller adaxial resin canals at the level of seed attachment. Seeds are inverted at maturity, display 180° rotational symmetry, and show differentiation of sclerotesta and sarcotesta. The results of a phylogenetic analysis support placement of H. juddii among the basal grade of taxodioid Cupressaceae ( Farjon, 2005). A transformational series of ovuliferous bract/scale complexes from voltziacean Voltziales to crown group Cupressaceae is presented to reveal the pattern and antiquity of evolution for modern cupressaceous conifer seed cone morphologies. Developmental studies of living cupressaceous seed cones indicate that the range of mature morphologies is strongly correlated with differences in the timing and rate of development for the bract, scale, and ovules, thus supporting the hypothesis that heterochrony plays a major role in the evolution of bract/scale form. This hypothesis is further supported by our growing understanding of developmental regulatory genetics. There are no currently recognized synapomorphies for living + fossil conifers. Nevertheless, these combined results do not support the hypotheses that some conifers have ancestrally simple seed cones nor that there have been parallel origins of Northern and Southern Hemisphere conifers. The overall body of evidence from both extinct and living conifers strongly supports the hypotheses of deep homology for seed cones and of monophyly for conifers s.s.

A review of the genus Eristophyton, with special focus on the Mississippian species

The genus Eristophyton is founded on woody axes of Mississippian age, showing a dense wood with an araucarioid type of pitting on the radial walls of tracheids and small numerous pits in cross-fields. Distinctive characters of Eristophyton are related to its primary vascular body, especially the structure and arrangement of primary xylem strands, and structure and size of leaf traces. Species described from Permian deposits are not considered in this review, which focuses on the three Mississippian species, E. beinertianum, E. fasciculare, and E. waltonii. Eristophyton consist of plants of arborescent stature that produced a large amount of vascular and cortical secondary tissues, and had their leaves borne on the youngest axes. Anatomical and morphological similarities with Bilignea and Pitus are emphasized. Compared to all other arborescent genera of lignophytic affinities known for the Mississippian, Eristophyton has the widest geographical and stratigraphical extent.

Aspects of inflorescence and floral development in the putative basal angiospermAmborella trichopoda(Amborellaceae)

Amborella has woody axes whose development is intrinsically plagiotropic and determinate. The tree habit is achieved through overtopping of older axes by basally produced younger axes, as in Mangenot's model. Inflorescence units, which are produced in the axils of distal leaves, may be described as extended cymes, each branch ending in a flower. Basal bracteoles have a decussate arrangement, which is modified to an alternate phyllotaxis distally. Flowers produce one or more additional bracteoles with a rapid transition to the spiral phyllotaxis of the broad overlapping tepals. In this transition the initially conical floral apex becomes invaginated to form a floral cup, with subsequent appendages appearing on its inner margin. The floral apex then forms the flat base of the cup but retains a discrete single tunica layer. The receptacular bowl is deepened and narrowed by the basal meristem of each appendage, the last formed floral organs usually consuming the floral meristem. Sexual parts are more numerous in male than female flowers, accounting for their size difference, but primordia of stamens and carpels are initially very similar. Floral symmetry is largely a consequence of close packing of appendages within the floral cup. In its initial stages of development the flower does not conform to any conventional floral model in angiosperms and is better regarded as highly specialized rather than ancestral in its synorganization. This is not unexpected in a lineage of such long independent evolution.Key words: Amborella, basal angiosperm, development, inflorescence, primitive flower.

Oxidative pentose phosphate pathway and pyridine nucleotides in relation to heartwood formation in Robinia pseudoacacia L.

Most tree species show in the inner parts of their woody axes often a dark colored zone, the heartwood. Its formation is a genetically determined, programmed cell death which is characterized by the activation of metabolic pathways which lead to the formation of phenolic heartwood extractives. In the present paper we report on the key position of the oxidative pentose phosphate pathway (OPP) for this process. The OPP plays a crucial role in anabolic processes and is involved in the interconversion and rearrangements of sugar-phosphates with the net production of NADPH. In tissues of Robinia pseudoacacia L. which are transferred to heartwood, enhanced activities of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) are present. A consequence of these increased enzyme activities is a shift in the pyridine nucleotide pool towards NADP+NADPH at the expense of NAD+NADH. These alterations in the metabolism and the redox status probably provide precursors and reduction equivalents being required for the synthesis of heartwood phenolics. The non heartwood forming species Acer pseudoplatanus L. shows neither a radial gradient nor seasonal changes in the amounts of pyridine nucleotides across the trunkwood. The results are discussed in connection with programmed cell death, mitochondrial activity, and heartwood formation.

Extractable activities and protein content of sucrose-phosphate synthase, sucrose synthase and neutral invertase in trunk tissues of Robinia pseudoacacia L. are related to cambial wood production and heartwood formation

The presence of sucrose synthesizing and degrading enzymes and the correlation of their enzyme activity with cambial growth and heartwood formation are demonstrated in trunks of Robinia pseudoacacia L., black locust. Sucrose is formed by sucrose-phosphate synthase (SPS; EC 2.4.1.14), predominantly in the storage part of the sapwood. In the cambial differentiation zone and the sapwood-heartwood transition zone, both of which constitute carbohydrate sinks, sucrose is primarily cleaved by sucrose synthase (SuSy; EC 2.4.1.13) and a neutral invertase (NI; EC 3.2.1.26). In spring, enhanced activities of SuSy and NI were found in the differentiating xylem tissues. This coincided with elevated SPS rates at the sites of starch mobilization. Heartwood formation in autumn, a period of intense accumulation of phenolics in the innermost living wood tissues, was accompanied by high activities of SuSy and NI. Increased SPS and NI activities in all tissues of winter samples could be correlated with cold acclimation. Probing of SPS and SuSy protein from black locust with heterologous antibodies revealed a subunit size of 130 kDa for SPS and of 89 kDa for SuSy. Both SPS and SuSy exhibited a linear correlation between catalytic activity and amount of enzyme protein with respect to the radial profile from bark to inner core and with respect to the seasonal course. The highest amounts of SuSy-specific mRNA were detected in differentiating xylem in summer and the sapwood-heartwood transition zone in autumn. These data are taken as evidence for a pivotal role of SuSy in supplying carbon skeletons for the biosynthesis of secondary substances in woody axes.

A model of the variation of water potential and diameter within a woody axis cross-section under transpiration conditions

The spatio-temporal variation of water potential and the corresponding changes in diameter in a woody axis cross-section have been modelled. The two-dimensional space model is based on the assumption that the water flux is regulated by Darcy’s law which leads to a diffusion type equation. This equation takes into account the water movements to and from the xylem vessels in space and time. The water potential of the vessels being given, a numerical solution provided the values of the water potential variations of the wood and peripheral elastic tissues in the woody axis cross-section throughout the day. By specifying that the predawn water potential equilibrates throughout the whole section, this study enabled us to determine a range of satisfactory values of parameters. A first validation was given by an application of the model to a peach-tree. It was performed by comparing the calculated variations in diameter of a trunk to those which were measured. In conclusion we discuss some physiological consequences of the model.

Distribution of Phenylalanine Ammonia Lyase and Chalcone Synthase within Trunks of Robinia pseudoacacia L.

Abstract:During heartwood formation, a kind of apoptosis in the inner parts of woody axes, phenolic substances are accumulated by in situ biosynthesis. In Robinia pseudoacacia L, these compounds are mainly flavonoids. In the present work, we performed a study to show if there is a correlation between measurable activities and detectable protein levels of phenylalanine ammonia lyase (PAL; EC 4.3.1.5) and chalcone synthase (CHS; EC 2.3.1.74), key enzymes of general phenylpropanoid metabolism and flavonoid biosynthesis, respectively. After separation of total protein extracts by one‐dimensional micro‐gel electrophoresis, newly emerging polypeptides were detectable within the sapwood‐heartwood transition zone, pointing toward a transient activation of metabolism shortly before cell death occurs. Most prominent was a polypeptide around 46 kDa. By immunoblotting, this band was identified as a CHS subunit. Thus, the exclusive presence of both enzyme protein and extractable enzyme activity of CHS in the heartwood bordering tissue was shown. In contrast, levels of PAL protein were similar in all xylem tissues which contain living cells. PAL activity, however, was measurable only in the differentiating xylem and the sapwood‐heartwood transition zone. From these results we conclude that during heartwood formation, CHS and PAL differ in their mode of regulation. It seems likely that CHS activity is regulated at the level of enzyme protein while PAL regulation is most probably post‐translational.

Taphonomy of plant fossils from the Viséan of East Kirkton, West Lothian, Scotland

ABSTRACTThe Viséan sequence at East Kirkton contains abundant plant fossils which show a wide range of preservation states. Most of the plant fragments are allochthonous, but stigmarian rootlets are foundin situat the top of the sequence and form mats near the base, where they are preserved in cherts. Axes have commonly been reworked within tuffs at the base. The majority of the plants are preserved as fragmentary compressions, although mineral replacement of the organic matter has occurred in some places. A number of woody axes which have been permineralised by phases of calcite and silica are found in the limestone and tuffs of the sequence. These axes often show complex mineralisation patterns and can occur at the centre of stromatolitic nodules. Some are well preserved and appear to have been permineralised rapidly whereas others show evidence of decay prior to calcite growth or degradation after stromatolite developed. Fusain (fossil charcoal) is abundant in the sequence, in addition to fusain transition fossils caused by partial charring, which suggests the occurrence of palaeowildfires in the area. The plant fossils have been assigned to a number of categories (some of which are new), based on their varied preservation states.

Construction and economy of plant stems as revealed by use of the Bic-method

The Bic-method, developed by F. Otto for the investigation and classification of light-weight structures in architecture and then also applied to constructions in nature, can be used for mechanical analysis of plants. It allows statements on tension and pressure stability of plant stems and a direct comparison of stems with different anatomy. The multiplication of the Bic-value by an energy value (construction cost or energy content of the plant organ) results in a dimensionless constructive expenditure value, which is comparable to the value of the construction economy in architecture. This value may then be related to the average lifespan of the plant organ. Stems of Ephedra foeminea, Pachysandra terminalis, and Taxus baccata as well as flower stalks of Cyclamen persicum and Taraxacum officinale are investigated to show the applicability of the method. The lowest Bic- values (highest mechanical stability) are found for the lignified stems of Ephedra and Taxus. The constructive expenditure values are higher in herbaceous than in woody axes; in relation to the average life span the long-living lignified tissues show by far the lowest values. The very high values of the flower-stalks are attributed to the fact that short-lived organs also need a minimum expenditure of materials and energy for their construction.

Construction and Economy of Plant Stems as Revealed by Use of the Bic-method

The Bic-method, developed by F. Otto for the investigation and classification of light-weight structures in architecture and then also applied to constructions in nature, can be used for mechanical analysis of plants. It allows statements on tension and pressure stability of plant stems and a direct comparison of stems with different anatomy. The multiplication of the Bic-value by an energy value (construction cost or energy content of the plant organ) results in a dimensionless constructive expenditure value, which is comparable to the value of the construction economy in architecture. This value may then be related to the average lifespan of the plant organ. Stems of Ephedra foeminea, Pachysandra terminalis, and Taxus baccata as well as flower stalks of Cyclamen persicum and Taraxacum officinale are investigated to show the applicability of the method. The lowest Bic- values (highest mechanical stability) are found for the lignified stems of Ephedra and Taxus. The constructive expenditure values are higher in herbaceous than in woody axes; in relation to the average life span the long-living lignified tissues show by far the lowest values. The very high values of the flower-stalks are attributed to the fact that short-lived organs also need a minimum expenditure of materials and energy for their construction.

Nova forma do complexo Vertebraria nos argilitos carbonosos da Formação Rio Bonito, Santa Catarina, Brasil

Available evidence presented here supports the approach by MUSSA (1978) that Vertebraria ROYLE really comprises a complex of forms. Schopficaulia n. g. is a distinct new unit which presents external morphological characters similar to Vertebraria, but whose anatomical plan clearly represents aerial vascular organs, such as branching woody axes showing adventitious rootlet traces and undifferentiated branch or foliar traces. The pith is unquestionably indicative of plants of the runner, climbing or shrub type adapted to a swampy environment. The fact that vertebrarian-type axes are restricted to Gondwanic coal fields is consistent with the environmental interpretation inferred from the pith plan. All indications substantiate the viewpoint that the plants lived at the very site where they were later fossilized.

Occurrence of Reaction Wood in Branches of Dicotyledons and Its Role in Tree Architecture

Lateral branch and young leader axes of 122 species of dicotyledonous trees in 46 families, displaying a variety of architectural models, were surveyed for presence of reaction wood (RW) as defined by gelatinous wood fibers (G-fibers). Distinct G-fibers occurred in 56 species, mostly in the upper half of the axis. There was a positive correlation between changes in axis orientation and position of the RW in 22, or one-fourth, of the species showing changes in branch orientation. Many species show an increase in branch angle; i.e., branches become more horizontal with age. Among these, Hevea (Rauh's architectural model), Endospermum, and Terminalia (both Aubreville's model) first produce RW on the lower side near the pith and later on the upper side. The erection of a lateral branch, i.e., a decrease in branch angle, to form the new leader in Koriba's model is correlated with RW on the upper side of the branch in Hura, but not in other species with this model. Many species with Troll's model, in which the arched leader becomes vertical, have RW on the upper side of the leader axis, e.g., Hymenaea, Fagus, Banara, Celtis, Ulmus, Piscidia, and Brownea. In some species with Koriba's or Troll's models, the wood on the upper side is thinner walled and less lignified, and the phloem rays are longer radially and more dilated tangentially than on the lower side of the axes. Thus, in some trees the normal reorientation of woody axes is related to the distribution of G-fibers, which cause longitudinal tensile stress, and/or other anatomical differences within those axes. This suggests an active, endogenous role for RW in the establishment of the architecture of these examples, in addition to its previously known supportive role in horizontal and displaced axes.