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The wood anatomy of Gymnanthes klotzschiana was studied, to assess whether there are variations in the secondary xylem under different geopedological conditions. The species is dominant in subtropical alluvial forests and can be established in different ecological conditions, especially regarding soil water regime. Wood samples were collected in the plain of the Iguaçu River, in Paraná, Brazil, encompassing three geopedological conditions: gleysol, fluvisol and psamment, characterized by varying degrees of water saturation, ranging from very poorly drained to heavily drained. Considerable intraspecific variations were found in the xylem in response to geopedological conditions. Most of the variation occurs in attributes related to the biomechanical and hydraulic functions (e.g. fibers and vessels), with cells smaller in gleysol, larger in fluvisol and intermediate in psamment. For some variables, the xylem has similar responses in conditions of water deficit and permanent water saturation, indicating a probable influence of physiological drought. The phenotypic plasticity of the species explains its high adaptability to the selective and variable conditions of riparian environments. The study contributes to understanding the species' ecological responses, highlighting its relevance as a keystone species in the dynamic and fragile ecosystems of the floodplains, fundamental for the maintenance of many ecosystem services. [ABSTRACT FROM AUTHOR]

Continuing the study of petrified gymnosperm trunks recovered from the Pedra de Fogo Formation, we identify here two new taxa from the Permian deposits of the Parnaíba Basin, northeastern Brazil. One taxon is an endemic form named Ductolobatopitys mussae Conceição, Neregato et Iannuzzi, nov. gen., nov. sp., characterized by solenoid, lobed and non-septate heterocellular pith, cauline bundles with endarch maturation, and secondary xylem with araucarian radial pitting on the tracheid walls. The other form is assigned to the genus Kaokoxylon , which has been recorded from most of Gondwana, including the Parnaíba Basin, but is recorded for the first time from the Pedra de Fogo Formation with the new species Kaokoxylon brasiliensis. It is characterized by solid, non-septate heterocellular pith with sclerenchyma cells, endarch cauline bundles, and uni-to triseriate radial pitting on the walls of the tracheids. The sedimentological interpretations of the outcrops where the fossils were collected indicate that these plants lived on the shores of large continental lakes, with relatively high humidity but possibly periods of drought. These inferences are supported by growth interruptions in the secondary xylem, the presence of calamitalean and tree-fern stems, and microbialites that crop in the same area. These new finds not only increase the known diversity of the flora in the Pedra de Fogo Formation, but also provide more accurate information for understanding the floristic elements that formed the subtropical flora during the Cisuralian in this basin in Western Gondwana. [ABSTRACT FROM AUTHOR]

Distribution and abundance of charcoal in coal seams (in form of pyrogenic macerals of the inertinites group) have been considered as a reliable tool to interpret the local and regional palaeo-wildfire regimes in peat-forming depositional environments. Although the occurrence of inertinites is globally well documented for the Late Palaeozoic, the description of palaeobotanical evidence concerning the source plants of such charcoal is so far largely missing. In the present study, we provide the first detailed analysis of macro-charcoal preserved in the Barro Branco coal seam, Rio Bonito Formation, Cisuralian of the Paraná Basin, Santa Catarina State, Brazil. Charcoal, in form of macro-charcoal and inertinites, was documented in all the six coal-bearing strata that compose the succession, confirming the occurrence of recurrent palaeo-wildfires during its deposition. Reflectance values indicated a mean charring temperature reaching ~515°C (and up to 1,045°C in excess) and the macro-charcoal exhibits anatomical features of secondary xylem of Agathoxylon. Combination of results derived from palaeobotanical and petrological data demonstrates that gymnosperm-dominated vegetation was repeatedly submitted to fire events and reinforced the hypothesis that Gondwanan mires were high-fire systems during the Cisuralian. [ABSTRACT FROM AUTHOR]

Summary: Predicting responses of tropical forests to climate change‐type drought is challenging because of high species diversity. Detailed characterization of tropical tree hydraulic physiology is necessary to evaluate community drought vulnerability and improve model parameterization. Here, we measured xylem hydraulic conductivity (hydraulic efficiency), xylem vulnerability curves (hydraulic safety), sapwood pressure–volume curves (drought avoidance) and wood density on emergent branches of 14 common species of Eastern Amazonian canopy trees in Paracou, French Guiana across species with the densest and lightest wood in the plot. Our objectives were to evaluate relationships among hydraulic traits to identify strategies and test the ability of easy‐to‐measure traits as proxies for hard‐to‐measure hydraulic traits. Xylem efficiency was related to capacitance, sapwood water content and turgor loss point, and other drought avoidance traits, but not to xylem safety (P50). Wood density was correlated (r = −0.57 to −0.97) with sapwood pressure–volume traits, forming an axis of hydraulic strategy variation. In contrast to drier sites where hydraulic safety plays a greater role, tropical trees in this humid tropical site varied along an axis with low wood density, high xylem efficiency and high capacitance at one end of the spectrum, and high wood density and low turgor loss point at the other. [ABSTRACT FROM AUTHOR]

Pseudofrenelopsis and Brachyphyllum are two conifers that were part of the Lower Cretaceous (Aptian) taphoflora of the Crato Formation, Araripe Basin, northeastern Brazil. The former genus includes, so far, P. capillata and indeterminate species, whilst the latter is mainly represented by B. obesum, the most common plant megafossil recovered from that stratigraphic unit. Here, the stem and leaf anatomy of Pseudofrenelopsis sp. and B. obesum specimens is revisited, including the first report of some epidermal and vascular traits for both taxa from the Crato Formation. Along with its paleoecological significance, the new data suggest the presence of more than one Pseudofrenelopsis species in the Aptian taphoflora of the Araripe Basin and further support the taxonomic placement of B. obesum within Araucariaceae. [ABSTRACT FROM AUTHOR]

• The extreme drought period in 2014 combined with 37% throughfall reduction was studied. • Potassium (K) fertilization increased changes in vessel traits in response to drought. • After rehydration, K fertilization enhanced the recovery of xylem hydraulic conductivity. • The positive effects of K on tree growth were maintained throughout the rotation. • A 37 % throughfall reduction only affected tree growth for the first 2.5 years after planting. Most Eucalyptus plantations in Brazil are located in regions currently experiencing periods of water shortage, where fertilizers such as potassium (K) are intensively used to achieve high productivity. In a changing environment, improving our understanding of the effects of K nutrition on tree growth rates and xylem plasticity across tree ages as a function of climate is crucial for forest management. The objective of this study was to gain insight into the interactive effects of K fertilization, water availability, and tree age on stem growth and changes in xylem traits of E. grandis trees over a full rotation. Changes in growth and xylem traits in response to a severe drought that occurred in 2014 were also studied. An experimental plantation of E. grandis trees was established in São Paulo, Brazil and monitored over a full 6-year rotation period. The experiment consisted of a split-plot design with two water supply regimes (37 % throughfall reduction vs undisturbed throughfall) and two fertilization regimes (K supply vs control). Basal area increment (BAI) was monitored using band dendrometers at 14-day intervals from 1 to 6 years after planting. Xylem traits including wood density (WD), cell wall fraction (CWF), cell density (CDen), theoretical xylem specific hydraulic conductivity (Kst), vessel diameter (VD), vessel density (VDen), vessel area (VA), and the vulnerability index (VI) were measured in 6-month periods (rainy and dry seasons) throughout the rotation. K fertilization increased BAI by a factor of 3 in plots where throughfall was not disturbed but led to an interruption of tree growth during the severe drought in 2014. The growth patterns showed a positive effect of K for growth recovery following drought. Throughfall reduction affected growth only in K-fertilized trees and up to 30 months of age. K fertilization also increased changes in xylem traits in response to drought in E. grandis trees. The main changes occurred in vessel traits, with a 53 % decrease in Kst during the drought but recovery was rapid after the first rainfall events. High plasticity was also observed for WD, CWF, CDen, and VI. [ABSTRACT FROM AUTHOR]

A gelified wood from the late Aptian Maceió Formation (Sergipe–Alagoas Basin, northeastern Brazil) was studied under scanning electron microscopy and organic petrography allowing for the record of the fossil-species Brachyoxylon patagonicum , likely belonging to the Cheirolepidiaceae family. The anatomical structure of the secondary xylem is characterized by mixed type of radial tracheary pitting, composed exclusively by uniseriate bordered pits, in separated, contiguous and compressed arrangements. Cross-field pits are of the araucarioid type, xylem rays are uniseriate or rarely partially biseriate, and probable sporadic traumatic resin canals are present. The present record expands the paleobiogeographic distribution of the fossil-genus in South America and amplifies its climatic tolerance, since the parent plants lived in the Aptian Tropical Equatorial Hot arid belt. The presence of fungal remains within the wood tissue, and the absence of signs of plant defense against fungal decay suggest saprophytic fungus–wood interactions that likely occurred during a stage of aerobic exposure before burial. • A record of cheirolepidiacean wood for the Brazilian Aptian. • Wood preservation by gelification was determined by organic petrography. • Periquatorial occurrence of Brachyoxylon amplified its climatic tolerance. [ABSTRACT FROM AUTHOR]

Solenoid piths are formed by systems of secretory ducts or canals, and they are relatively common in petrified gymnosperms from the Permian of Gondwana. We described herein two new taxa, Polycanaloxylon merlottii gen. et sp. nov. and Europoxylon garapensis sp. nov., from the Pedra de Fogo Formation (Cisuralian), northeastern Brazil. In both species the pith is non-septate and solenoid, primary xylem bundles have endarch maturation, rays are short and uniseriate, pits on the radial walls of tracheids are commonly uni to biseriate, cross-field pitting is cupressoid and wood is pycnoxylic. Whereas P. merlottii has a solenoid pith with a parenchyma sheath and sclerenchyma cells, E. garapensis is distinguished by a pith that only has secretory canals and parenchyma cells. In addition to expanding the distribution area of a typical Euramerican taxon into Parnaíba Basin, the report of Europoxylon reinforces a connection between these areas in the Late Pennsylvanian, thus enabling the dispersion of floristic elements. Solenoid forms are especially common in Kungurian sedimentary deposits of southern Brazil, and possibly India. However, since the occurrence of them seems to be linked to specific habitats, it should be proven that such environments are indeed contemporaneous in order to use these stems as a tool for relative dating in Gondwanan localities. • New taxa Europoxylon garapensis and Polycanaloxylon merlottii are described. • They have solenoid pith, which is a feature commonly reported in Gondwana. • The report of Europoxylon in Gondwana suggests a dispersal in the Pennsylvanian. • Plants with solenoid piths may not be restricted to the middle to late Kungurian. [ABSTRACT FROM AUTHOR]

The xylem-limited bacterium Xylella fastidosa causes the widely disseminated citrus variegated chlorosis disease (CVC). In Brazil, CVC has been known for more than 20 years and affects only sweet orange. Lime and mandarin have remained free of symptoms despite the high inoculum pressure. Knowing the mechanisms underlying this apparent resistance is important to devise new disease control strategies. The reaction of commercial sweet orange ('Caipira', 'Natal', 'Pêra', and 'Valencia'), lime (Mexican and Persian), mandarin ('Cleopatra', 'Cravo', 'Ponkan', and 'Sunki'), and the acid citrus species Rangpur to X. fastidiosa was compared in artificially inoculated seedlings, which were assessed for symptom expression, pathogen isolation, and the amount of apparently occluded xylem vessels in cross-sectioned leaf petioles. Only the sweet orange expressed typical CVC symptoms, varying from 53.8% in Valencia to 63.0% in Caipira. Average percentages of positive isolations (pi) and occluded vessels (ov) were higher in sweet orange (pi = 59.2 to 75.0: ov = 10.7 to 25.8) than mandarin (pi = 2.3 to 16.3; ov = 1.4 to 4.0), lime (pi = 0 to 5.4; ov = 0 to 2.1), or Rangpur (pi = 1,9; ov = 1.1). There were no obvious differences in xylem anatomy among all citrus varieties, suggesting that the mechanisms of resistance to CVC are not related to any physical variation in xylem structure. [ABSTRACT FROM AUTHOR]

A new petrified calamitalean is described from the Permian Motuca Formation, Parnaíba Basin, central-north Brazil. In contrast to all other three-dimensionally preserved Brazilian species, it represents a semi-self-supporting woody plant characterized by a distinctive branch system and cellular anatomy. Arthropitys buritiranensis sp. nov. is proposed to accommodate the new material. The branch architecture is composed of at least three types of branches: (i) principal woody side branches, (ii) up to three secondary woody branches per node, scattered along the stem or the principal side branches, and (iii) 8–11 leafy twigs per whorl, at every third, rarely the second node, without secondary growth. The wood is segmented into fascicular wedges and interfascicular rays, clearly visible only within the inner wood of the stem and woody branches. The tracheid walls of the secondary xylem have exclusively scalariform pits. Ray parenchyma cells have pitted horizontal walls. The new calamitalean was part of the riparian vegetation of tree ferns, calamitaleans and gymnosperms recorded in a distal fluvial plain setting. The wood shows irregular growth interruptions and, therefore, points to a seasonally dry climate that shaped even low latitude paleofloras of tropical Pangaea. • A new calamitalean stem is described from the Parnaíba Basin/Brazil. • Based on the anatomy and branching architecture Arthropitys buritiranenis sp. nov. is introduced. • A revised chart describing anatomically preserved calamitaleans is presented. [ABSTRACT FROM AUTHOR]

We describe the morphology and anatomy of cordaitalean tree stems preserved in Cisuralian lacustrine deposits of the Pedra de Fogo Formation, Permian of the Parnaíba Basin, northeastern Brazil. The remains consist of seven samples of petrified stems with septate pith (Artisia type) and preserved primary and secondary xylem. The anatomical features of these specimens support their classification in the genus Cordaixylon Grand'Eury, 1877, which is the first evidence of this genus not only in South America, but also in Gondwana. The sedimentological indicators suggest climatic seasonality during the deposition of the Pedra de Fogo unit. However, on a local scale, this area may have had a humid to sub-humid regional climate due to the presence of a large lacustrine system, which would allow these plants to grow in similar habitats to their locations in the Northern Hemisphere. The Parnaíba Basin contains a relatively high number of endemic taxa, but this genus is typical of the Euramerican Province and occurs in at least two areas of this basin. The presence of these trees and some forms of tree-ferns that are also shared with the Euramerican Province suggests the existence of a phytogeographic connection consisting of dispersal through a landscape linkage between the Euramerican tropics and northern Gondwana in the Late Pennsylvanian. This would make it possible for species to migrate between these two floristic provinces, a hypothesis that can be confirmed through further taxonomic and geological data. Finally, the presence of Cordaixylon in the Pedra de Fogo Formation can be considered indicative of a Cisuralian age for these rocks. • It is the first report of Cordaixylon in South America and Gondwana with two morphotypes. • This report increases the diversity of gymnosperms in Parnaíba Basin and it enables discussions about paleogeography. • Regional climatic conditions may certainly have been more humid than the suggested macroclimate models. [ABSTRACT FROM AUTHOR]

Anatomically preserved gymnosperm stems are relatively abundant in the Permian outcrops of the Parnaíba Basin, but their anatomy has rarely been studied in detail. Here we describe two new fossil gymnosperm trunks from the Lower Permian (Cisuralian) strata of the Pedra de Fogo Formation in the municipality of Nova Iorque, southern Maranhão State, northeastern Brazil. Two new genera et species are described, Novaiorquepitys maranhensis and Yvyrapitys novaiorquensis. These taxa have a broad, non-septate pith containing sclerenchyma and secretory cells, a parenchyma sheath, and a system of lacunae. Pycnoxylic secondary xylem with growth interruptions and the radial bordered pits on the tracheid walls are araucarian and mixed types. The recognition of two endemic forms indicates both a high degree of endemism for the flora of the Pedra de Fogo Formation and a higher taxonomic diversity of gymnosperm woods than hitherto noted. In addition, the anatomical characters of these taxa, together with sedimentological data and the presence in the same area of plants that live on the banks of water bodies or in wetlands (e.g., tree ferns and tree-calamitaleans), indicate that these woody plants lived near the shores of large lakes. These findings show that studies of Paleozoic woods in this region are potentially valuable. • There were identified two new genera and species based on pith and wood anatomy. • The new taxa are named as Novaiorquepitys maranhensis and Yvyrapitys novaiorquensis. • These woods significantly increase the taxonomic diversity of Permian gymnosperms in the Parnaíba Basin. • It was concluded that tree-dominated communities lived along the lake shores on mild climate conditions. [ABSTRACT FROM AUTHOR]

Amazonian droughts are increasing in frequency and severity. However, little is known about how this may influence species-specific vulnerability to drought across different ecosystem types. We measured 16 functional traits for 16 congeneric species from six families and eight genera restricted to floodplain, swamp, white-sand or plateau forests of Central Amazonia. We investigated whether habitat distributions can be explained by species hydraulic strategies, and if habitat specialists differ in their vulnerability to embolism that would make water transport difficult during drought periods. We found strong functional differences among species. Nonflooded species had higher wood specific gravity and lower stomatal density, whereas flooded species had wider vessels, and higher leaf and xylem hydraulic conductivity. The P 50 values (water potential at 50% loss of hydraulic conductivity) of nonflooded species were significantly more negative than flooded species. However, we found no differences in hydraulic safety margin among species, suggesting that all trees may be equally likely to experience hydraulic failure during severe droughts. Water availability imposes a strong selection leading to differentiation of plant hydraulic strategies among species and may underlie patterns of adaptive radiation in many tropical tree genera. Our results have important implications for modeling species distribution and resilience under future climate scenarios., (© 2020 The Authors. New Phytologist © 2020 New Phytologist Trust.)

• Paubrasilia echinata morphotypes present variation in wood anatomy according to a latitudinal range. • Specimens from higher latitudes show higher axial parenchyma percentage and larger vessels. • Café and Laranja morphotypes share more wood anatomical traits. • The wood anatomy do not corroborate previous molecular studies of P. echinata. • The wood anatomy do not support the categorization into subspecies or variety. Molecular and taxonomy approach have been made to understand the differences among the three morphotypes of Paubrasilia echinata , termed laranja, café and arruda. However, there is no wood anatomic study considering these morphotypes and their probable anatomical similarity. Considering as an endangered species with historical relevancy, it is crucial to recognize its wood anatomy to its conservation. This study aims to investigate the wood anatomy of P. echinata collected along its occurrence area (between 5°53′S 34°04′W and 22°56′S 42°30′W) and to examine the anatomical relationship among arruda, laranja and café morphotypes that was previously reported by molecular studies. The results indicate that the wood anatomy varied along its range of distribution a gradient of axial parenchyma and vessel features between the lower and higher latitudes was observed. Since arruda occurs in the collection sites of all four states studied, while café and laranja only in Bahia, the three morphotypes can be identified into of two groups based on wood anatomy: one formed by arruda samples and another by café and laranja, which differs from the previous molecular analysis. Combinations between higher percentage of axial parenchyma and wider vessels were observed in samples from RJ guarantying conductance and safety, while samples from RN and PB have smaller solitary vessels and scanty axial parenchyma, which could prevent embolisms. The present results do not support the categorization into subspecies or varieties. The findings also suggest that café and laranja share similar features than with arruda morphotype. [ABSTRACT FROM AUTHOR]

The absorption of atmospheric water directly into leaves enables plants to alleviate the water stress caused by low soil moisture, hydraulic resistance in the xylem and the effect of gravity on the water column, while enabling plants to scavenge small inputs of water from leaf-wetting events. By increasing the availability of water, and supplying it from the top of the canopy (in a direction facilitated by gravity), foliar uptake (FU) may be a significant process in determining how forests interact with climate, and could alter our interpretation of current metrics for hydraulic stress and sensitivity. FU has not been reported for lowland tropical rainforests; we test whether FU occurs in six common Amazonian tree genera in lowland Amazônia, and make a first estimation of its contribution to canopy-atmosphere water exchange. We demonstrate that FU occurs in all six genera and that dew-derived water may therefore be used to "pay" for some morning transpiration in the dry season. Using meteorological and canopy wetness data, coupled with empirically derived estimates of leaf conductance to FU (k fu ), we estimate that the contribution by FU to annual transpiration at this site has a median value of 8.2% (103 mm/year) and an interquartile range of 3.4%-15.3%, with the biggest sources of uncertainty being k fu and the proportion of time the canopy is wet. Our results indicate that FU is likely to be a common strategy and may have significant implications for the Amazon carbon budget. The process of foliar water uptake may also have a profound impact on the drought tolerance of individual Amazonian trees and tree species, and on the cycling of water and carbon, regionally and globally., (© 2019 John Wiley & Sons Ltd.)