Dicotyledonous Trees Research Articles

Soil geochemistry and constraint of tree seedlings immediately after germination on Macrotermes termite mounds in the Kruger National Park, South Africa.

Macrotermes termite mounds in the Kruger National Park occupy a significant part of the savanna landscapes, occurring at densities of up to 70 km-2 and often exceeding 10 m in width and 4 m in height. The mounds are usually devoid of trees, but have dense grass cover in wet years. As a result, these mounds form large patches of grassland amongst the wooded savanna. To our knowledge, it is not known why trees are largely excluded from the mounds. We analysed soil surface nutrient concentrations on and off mounds (0-2 cm deep, n = 80) to ascertain whether the availability of nutrients could be influencing competition between grasses and tree seedlings. The results showed that potential deficiencies in P, Ca, Cu, Zn and B in soils off the mounds are likely to be constraining plant growth. Notably, only B, with an average concentration of 0.19 mg kg-1, was likely to be limiting plant growth on the mounds. Notwithstanding likely interactions with herbivory and fire, we hypothesise that because grasses are far less susceptible to deficiencies of B than dicotyledonous trees, it is likely that grass competition with tree seedlings is considerably greater on mounds than off mounds.

Molecular Phylogenetics and Light Microscopy Reveal “True” and “False” Calacarines and Novel Genital Structures in Gall Mites (Acariformes, Eriophyoidea)

Gall mites (Eriophyoidea) are cosmopolitan microscopic phytoparasites that often transmit viruses and induce gallogenesis. The tribe Calacarini is diagnosed by a set of plesiomorphic and homoplastic traits, including elimination of setae sc shared with other lineages of Eriophyoidea. We reviewed data on the generic diversity of calacarines, revised the concept of the type genus Calacarus Keifer 1940, and proposed three zones (MZ, SMZ, LZ) in the prodorsal shields of calacarines to simplify descriptions of their shield patterns. We describe three new calacarine species (Calacarus baviensisn. sp., C. burchelliaen. sp., and Viginticus searsiaen. sp.) from indigenous dicotyledonous trees from South Africa and Vietnam and report on new findings of Paracalacarus podocarpi Keifer in Brazil, Jiangsuacarus sp. in the USA, and Calacarus pusillus Pye in Latvia and Russia. The latter represents the new most northern locality of Calacarini. Reinvestigating the type species of Jaranasia Chandrapatya & Boczek 2000 revealed that absence of setae l’’ II is the only character separating it from Jiangsuacarus Xue 2009. We proposed two new combinations: Jiangsuacarus sesleriae (Skoracka 2004) n. comb. (transferred from Jaranasia) and Procalacarus mussaendae (Keifer 1977) n. comb. (transferred from Calacarus). Partial sequences of Cox1 and 28S genes were obtained for six calacarines, some of them originating from old ethanol material kept at room temperature. Molecular phylogenetics revealed a stable cluster of “true” calacarine sequences comprising Calacarus, Jaranasia, Latitudo, and Viginticus and a polyphyletic group of erroneous sequences assigned to Calacarini in GenBank. All investigated females of calacarines have a pair of genital tubules associated with the vestibulum and hypothesized to participate in fertilization. This finding may contribute to resolving the question on how the fusion of gametes happens in gall mites.

Qualitative and quantitative phytochemical profiling of ethnomedicinal folklore plant- Globimetula oreophila

Globimetula oreophila is a hemiparasitic plant commonly called mistletoe, found growing on several dicotyledonous trees using them as a host for its root-like structure called haustoria. Globimetula oreophila has been used to cure a variety of ailments, including diarrhea, stomachache, headache, and fever. As a treatment for these ailments, the leaves and stem are boiled and the resulting decoction is drunk. The phytochemical compositions have not yet been scientifically confirmed despite their potential for medicinal use. The present study is aimed at investigating the leaves of G. oreophila fraction for phytochemicals, by qualitative and quantitative analysis. It was observed that from the qualitative screening, different fractions confirmed the presence of carbohydrates, saponins, cardiac glycoside, tannins, flavonoids, steroid/triterpene, and alkaloids. Anthraquinones were not observed in any of the fraction of G. oreophila plant. Further, the study of the quantitative findings revealed that the butanol fraction had more secondary metabolites when compared with other fractions and the crude extract. Higher flavonoid content was found in the butanol fraction as compared to crude ethanol extract (CEE) while phenols were found to be higher in crude ethanol extract as compared to the butanol fraction. There were significant differences in the total phytochemical contents of each fraction. The results also show that the analyzed plant is a beneficial source of secondary metabolites and may have contributed to the therapeutic use of the plant in traditional medicine for the management of diseases.

Palynostratigraphical review of the K–Pg boundary from the Ibero-Armorican Island: New data from the Maastrichtian dinosaur outcrop Veracruz 1 (Pyrenees, NE Iberian Peninsula)

The palynostratigraphy of the K–Pg boundary interval in SW Europe has been a subject of ongoing debate, despite numerous palynological studies in the region. To address this, we review previous publications and conduct analysis of new deposits to establish a palynostratigraphical chart. A total of 40 palynological studies within the Normapolles palynological province were reexamined to elucidate key taxa restricted to the Cretaceous (K-taxa), to the Maastrichtian–Danian interval (KPg-taxa) and those restricted to the Paleogene (Pg-taxa). Eventually, we propose 18 key taxa to differentiate a Maastrichtian from a Danian palynological assemblage within the Normapolles Province. Afterward, a palynostratigraphical analysis was carried out in Veracruz 1 (Aragonese Pyrenees), one of the more modern dinosaur-bearing sites of Europe. The palynological assemblage corresponded to an upper Maastrichtian age and was composed by pteridophyte spores, gymnosperms, angiosperms, dinoflagellate cysts, algae, and fungal spores. It was predominated by angiosperm pollen (Liliaceae, post-Normapolles, and triporate pollen). The plant communities in Veracruz 1 seem to be characterized by plants from an open coastal forest prevailed by Liliaceae flowering herbs and Juglandaceae/Myricaceae dicotyledonous trees and shrubs thriving in temperate-warm paleoclimate. The Gondwanan botanical influence was also supported by the presence of Bacumorphomonocolpites sp., as this taxon was previously recorded in other upper Maastrichtian deposits from Europe.

Phytolith analyses of tropical plants and topsoil from western Peninsular Malaysia and their implications for paleoenvironmental reconstruction

The underrepresentation of many important rainforest species in pollen records still hinders accurate paleovegetation reconstructions in tropical Southeast Asia. In this study, we conducted a modern phytolith study of 141 plant and 15 surface soil samples around the forests of Jerai Hill in western Peninsular Malaysia to evaluate the potential of phytolith assemblages as a proxy for indicating tropical vegetation types. In the plant samples, including many Dipterocarpaceae species, tracheary annulate/helical phytoliths occur most commonly, followed by silicified epidermis, silicified stomata, elongate entire, sclereid, trichomes, irregular. A few diagnostic phytoliths with unique morphological features are found in dicotyledonous trees, palms, and ferns, such as spheroid ornate (sph_orn) and spheroid echinate (sph_ech). In contrast, the phytolith assemblage of surface sediment is dominated by sph_orn, sph_ech, and spheroid psilate. This suggests that similar to pollen, the contribution from dominating forest vegetation rich in Dipterocarpaceae species is obscure in phytolith deposits. However, phytolith analysis highlights the representation of monocotyledons and a few dicotyledonous trees. The more sensitive indication of Poaceae short-cell phytoliths than pollen for parent plants implies that their ratio to forest indicator phytoliths might be a valuable proxy of landscape openness. Additionally, the statistical analysis confirms that phytolith assemblages in the heath forest are slightly different from those in the lowland dipterocarp forest, exhibiting their potential to indicate various vegetation types.

Palm live aboveground biomass in the riparian zones of a forest in Central Amazonia

AbstractAboveground biomass estimates in the Amazon region remain uncertain, partly due to extrapolations based mainly on samples collected in upland terrains of terra‐firme forests. Most biomass estimates were focused on dicotyledonous trees or included other plant groups as a category of trees. Palms dominate areas that represent 20% of the Brazilian Amazon. However, their contribution to biomass estimates and the variation within riparian zones remain poorly documented. We estimated the biomass of palms larger than 1–cm diameter at breast height (1.3 m aboveground) in riparian plots (n = 40); investigated the potential bias caused by the use of dicotyledonous‐ or family‐ rather than species‐level equations for biomass estimation; compared palm biomass between riparian and non‐riparian plots (n = 72); and evaluated the effects of soil, topography, and stream characteristics in riparian plots on palm biomass. Mean palm biomass in riparian zones estimated with species‐level equations (27.50 ± 12.94 Mg/ha, range: 3.32–63.27 Mg/ha) was three times greater than biomass estimated with a family‐level equation (9.04 ± 4.29 Mg/ha, range: 1.51–21.25 Mg/ha) and was greater than mean biomass estimated with a pantropical equation (20.46 ± 9.29 Mg/ha, range: 3.67–47.99 Mg/ha). Mean palm biomass in riparian zones was four times greater than in non‐riparian zones. Palm biomass was high in flatter areas with poorly drained soils, but lower around streams with higher discharge. Inclusion of palms can contribute to reducing the uncertainties in biomass estimates in Amazonian forests. Recognition of the importance of riparian zones may improve conservation policies.Abstract in Portuguese is available with online material.

First Report of Thread Blight Caused by Marasmius tenuissimus on Cacao (Theobroma cacao) in Peru.

Peru is the second largest producer of organic cocoa and one of the most important suppliers of fine aroma cocoa beans in the world (Sánchez et al. 2019). The fine aroma cocoa produced by smallholder farmers in the Bagua and Utcubamba Provinces, Amazonas Department, under the name of "Cacao Amazonas Peru", is protected by the Peruvian appellation rules (Díaz-Valderrama et al. 2020). Despite this importance, native diseases of the crop (Theobroma cacao) are poorly documented due to difficulty of access in this region. In November 2020 we conducted expeditions into Imaza District (4°47'09.4"S 78°16'51.6"W), a significant producer of fine aroma cocoa in terms of number of cultivated plots (4,651 out of 6,505 total in the Bagua Province) (INEI 2012). We visited 20 farms of < 2-ha in size; in 19 of these small farms, T. cacao trees were found infected with a white fungal thread blight and rhizomorphs covering branches and leaves. Disease incidence ranged from 90 to nearly 100%, and severity exceeded 80% on the eight farms with the most deficient phytosanitary management. Heavily infected leaves were hanging on branches by mycelial threads, harboring tiny (0.5 to 5.3 mm broad) white mushrooms. These symptoms and signs correspond to the thread blight disease constellation (TBD) of cacao caused by various species of Marasmius and Marasmiellus (Amoako-Attah et al. 2020). Mushrooms lacked a collarium, and their stipes were absent or rudimentary (< 2-mm long) and eccentric, consistent with Marasmius tenuissimus (Tan et al. 2009). Axenic cultures were obtained by surface sterilization of mycelium threads with 2% NaClO, rinsed three times in sterile water, plated on potato dextrose agar medium (PDA), and incubated for 7 days at 25°C. Hyphae was non-pigmented with clamp connections, consistent with the genus Marasmius. We extracted the DNA of isolate INDES-AFHP31 using the Wizard® Purification Kit (Promega Corp., Madison, Wisconsin) and sequenced the rDNA internal transcribed spacer 1 and 2 intervening the 5.8S subunit (ITS), and the 28S subunit (LSU) (Accession numbers: OM720123 and OM720135) according to Aime and Phillips-Mora (2005). The ITS and LSU sequences were 97.92 to 98.79% and 99.07 to 99.30% identical, respectively, with published sequences from M. tenuissimus from Ghana (Amoako-Attah et al. 2020). The pathogenicity test was conducted by inoculation of ten healthy cacao leaves with 7-day-old mycelium PDA discs of isolate INDES-AFHP31. An equal number of healthy cacao leaves were inoculated with PDA discs without mycelium as control. The observation of TBD symptoms and signs in the non-control set of cacao leaves starting at 3 days post inoculation, and the re-isolation of the same fungus from infected tissue confirmed its pathogenicity on cacao. Isolate INDES-AFHP31 was deposited as a dried culture into the herbarium Kuélap of the Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas (voucher KUELAP-2251). Marasmius tenuissimus was originally reported from dead and living twigs and leaves of unidentified dicotyledonous trees from Indonesia, Brazil, and Bolivia (Singer 1976). However, it was first associated with TBD of cacao in Ghana in 2020, being the most frequently TBD-causing fungus isolated in the country (Amoako-Attah et al. 2020). Its discovery in 19 of the 20 surveyed cacao farms in Imaza District, Amazonas, Peru, reveals its importance as a cacao pathogen in the Western hemisphere.

Paradigms of actinorhizal symbiosis under the regime of global climatic changes: New insights and perspectives.

Nitrogen occurs as inert and inaccessible dinitrogen gaseous form (N2 ) in the atmosphere. Biological nitrogen fixation is a chief process that makes this dinitrogen (N2 ) accessible and bioavailable in the form of ammonium (NH4 + ) ions. The key organisms to fix nitrogen are certain prokaryotes, called diazotrophs either in the free-living form or establishing significant mutual relationships with a variety of plants. On such examples is ~95-100 MY old incomparable symbiosis between dicotyledonous trees and a unique actinobacterial diazotroph in diverse ecosystems. In this association, the root of the certain dicotyledonous tree (~25 genera and 225 species) belonging to three different taxonomic orders, Fagales, Cucurbitales, and Rosales (FaCuRo) known as actinorhizal trees can host a diazotroph, Frankia of order Frankiales. Frankia is gram-positive, branched, filamentous, sporulating, and free-living soil actinobacterium. It resides in the specialized, multilobed, and coralloid organs (lateral roots but without caps), the root nodules of actinorhizal tress. This review aims to provide systematic information on the distribution and the phylogenetic diversity of hosts from FaCuRo and their micro-endosymbionts (Frankia spp.), colonization mechanisms, and signaling pathways. We also aim to provide details on developmental and physiological imperatives for gene regulation and functional genomics of symbiosis, phenomenal restoration ecology, influences of contemporary global climatic changes, and anthropogenic impacts on plant-Frankia interactions for the functioning of ecosystems and the biosphere.

Taylor’s Power Law for Leaf Bilateral Symmetry

Leaf shape and symmetry is of interest because of the importance of leaves in photosynthesis. Recently, a novel method was proposed to measure the extent of bilateral symmetry in leaves in which a leaf was divided into left and right sides by a straight line through the leaf apex and base, and a number of equidistant strips were drawn perpendicular to the straight line to generate an equivalent number of differences in area between the left and right parts. These areal differences are the basis for a measure of leaf bilateral symmetry, which was then examined to see how well it follows Taylor’s power law (TPL) using three classes of plants, namely, 10 geographical populations of Parrotia subaequalis (H.T. Chang) R.M. Hao et H.T. Wei, 10 species of Bambusoideae, and 10 species of Rosaceae. The measure of bilateral symmetry followed TPL for a single species or for a class of closely related species. The estimate of the exponent of TPL for bamboo plants was significantly larger than for the dicotyledonous trees, but its goodness of fit was the best among the three classes of plants. The heterogeneity of light falling on branches and leaves due to above-ground architectural patterns is an important contributor to leaf asymmetry.

New phytoptids (Eriophyoidea, Phytoptidae) from southern African endemic dicotyledons: description of two new species of Solenocristus n. g. and updated key to world genera of the tribe Sierraphytoptini

A new phytoptid genus and two new species, Solenocristus karooensis n. g. &amp; n. sp. and S. searsius n. sp. (Phytoptidae, Sierraphytoptinae, Sierraphytoptini), were collected in the Eastern and Western Cape provinces of South Africa, from southern African endemic dicotyledonous trees Schotia afra (Fabaceae) and Searsia lucida (Anacardiaceae) respectively. They are described and illustrated with the aid of conventional light microscopy and low temperature scanning electron microscopy. Females of both new species possess a distinct pregenital plate divided into two parts by a subcuticular medial ridge. Additionally, in S. karooensis n. sp. the movable digit of the male chelicerae varies in length: among six observed males, three males had a movable digit (md) twice shorter than the fixed digit (fd), in one male it was slightly shorter than fd and in the remaining two males md and fd were of the same length. An updated key to the world genera of the tribe Sierraphytoptini is given. The key incorporates data on seven sierraphytoptine genera including three genera (Neoprothrix Reis &amp; Navia, Solenoplatilobus Chetverikov &amp; Craemer and Solenocristus n. g.) which were described since the last generic key of Eriophyoidea by Amrine et al. (2003) was published.

New pseudotagmic genus of acaricaline mites (Eriophyidae, Acaricalini) from a South African palm Hyphaene coriacea and remarks on lateral opisthosomal spines and morphology of deutogynes in Eriophyoidea

A new genus, Tumescoptella n. g., with two new sympatric species Tumescoptella aculeata n. sp. and T. rotundiscuta n. sp., was found on the indigenous South African palm Hyphaene coriacea, Lala palm. Both species are described and illustrated with the aid of conventional light microscopy, confocal laser scanning microscopy and low temperature scanning electron microscopy. Additionally, a new record of Tumescoptes dicrus Meyer collected from Phoenix reclinata (Arecaceae), near Kirstenbosch Gardens (Cape Town, South Africa), is reported. Morphologically the Tumescoptella n. g. is most similar to Tumescoptes Keifer, but possesses a more reduced chaetome and more derived pseudotagmosis. Pseudotagmosis is one type of body consolidation in vagrant eriophyoids, realized through the formation of dorsal opisthosomal plates, pseudotagmata. Along with previously described pseudotagmata (prodorsum, cervix, postprodorsum, superpostprodorsum, pretelosoma, and telosoma), a new term, anteroscutum, is proposed for the complex pseudotagma formed as a fusion of the three anterior pseudotagmata (prodorsum+cervix+postprodorsum) in several phyllocoptine mites from palms. An anteroscutum is present in monotypic Scolocenus Keifer from coconut and in the new genus Tumescoptella n. g. Protogyne females of Tumescoptella n. g. have uncommonly large lateral opisthosomal spines. Along with tiny spinules, triangular cuticular plates, band-shaped processes, and areas of thickened cuticle, the lateral spines belong to a common group of serial derivatives of dorsal opisthosomal annuli. We give a brief review on variation of spine-like structures across taxa of Eriophyoidea and their morpho-functional evaluation. Contrary to protogyne females, deutogyne females of T. aculeata n. sp. lack lateral spines, and they possess a smoother topography of the anteroscutum. Morphological similarity of these deutogynes with mites of the less transformed genus Tumescoptes is in accordance with a previous hypothesis on the possible correspondence of deutogyne morphology to that of an ancestral taxon. Two hypotheses on the origin of the presumably monophyletic group of Tumescoptes-like phyllocoptines (TP) from palms, comprising genera Scolocenus, Tumescoptella n. g., Tumescoptes, and Pseudotagmus, are proposed based on morphological similarity with two groups of eriophyoid genera: (a) pseudotagmic genera associated with aboriginal Asian dicotyledonous tropical trees, and (b) South American phyllocoptines from arecoid palms.

The mutualism of Melissotarsus ants and armoured scale insects in Africa and Magadascar: distribution, host plants and biology

Species of the ant genus Melissotarsus Emery are widespread in the Afrotropical region (three species, namely M. beccarii Emery, M. emeryi Forel and M. weissi Santschi) and in the Madagascar region (one species, namely M. insularis Santschi). The ants of all these species tunnel their galleries in live wood of various dicotyledonous trees, close to the bark surface. The ants maintain within these galleries populations of different species of armoured scale insects. A review is presented on the geographical distribution of mutualism, of the Melissotarsus species, the associated 10 species of armoured scale insects, and the host plants on which the mutualism takes place. The ecology of the mutualism is discussed also, together with suggestions on the benefits that the partners gain from the associations.

Ecology and diversity of leaf litter fungi during early-stage decomposition in a seasonally dry tropical forest

Leaf litter samples of 12 dicotyledonous tree species (belonging to eight families) growing in a dry tropical forest and in early stages of decomposition were studied for the presence of litter fungi. Equal-sized segments of the leaves incubated in moist chambers were observed every day for 30 d for the presence of fungi. Invariably, the fungal assemblage on the litter of each tree species was dominated by a given fungal species. The diversity of fungi present in the litter varied with the tree species although many species of fungi occurred in the litter of all 12 species. A Pestalotiopsis species dominated the litter fungal assemblage of five trees and was common in the litter of all tree species. The present study and earlier studies from our lab indicate that fungi have evolved traits such as thermotolerant spores, ability to utilize toxic furaldehydes, ability to produce cell wall destructuring enzymes and an endophyte-litter fungus life style to survive and establish themselves in fire-prone forests such as the one studied here. This study shows that in the dry tropical forest, the leaf litter fungal assemblage is governed more by the environment than by the plant species.

Habitat use patterns and food habits of the Kashmir red deer or Hangul (Cervus elaphus hanglu) in Dachigam National Park, Kashmir, India

The last surviving wild population of the Kashmir red deer (Cervus elaphus hanglu) or Hangul inhabits the Dachigam National Park located near Srinagar city of Kashmir, India. This paper presents data from February 2001 to December 2009 on habitat use patterns and food habits of the Kashmir red deer. Investigations based on surveys along trails indicate that Hangul showed significant differences in the use of different habitat types (F = 6.49; P = 0.001) between seasons. Males showed significant differences in habitat utilization both within a season (F = 3.63; P ≤ 0.013) and between seasons (F = 1.50; P ≤ 0.087). Females showed differences in their habitat use within season but not between seasons (F = 14.771; P ≤ 0.577). Surveys showed the deer predominantly using the lower and middle altitudes (1700–1900 m and 1900–2300 m) with no significant gender differences. The riverine and mixed oak forests showed the highest mean deer pellet density/ha (153.71 ± 173.43, n = 418 and 188.60 ± 56.41, n = 114, respectively). The grassy/rocky cliff habitat showed the lowest mean pellet density/ha (55.92 ± 18.32, n = 228). The Hangul diet constituted mainly of dicotyledonous shrubs and trees (45.45 and 80.77%), forbs/herbs (36.36 and 19.23%), monocotyledon grasses and herbs (18.18 and 16.22%) in spring and winter, respectively. Summer diet comprised 42.86% forbs, 19.05% grass/sedges and 38.10% browses. In autumn, Hangul fed mainly on dicotyledonous shrubs. The habitat use patterns of Hangul are comparable with those of the European red deer and are influenced by availability of food, cover, shelter, altitude, slope, aspect and the level of disturbance. The habitats with ideal conditions for utilization but with a meager disturbance were avoided by Hangul. Recommendations are given for better and effective management, protection and conservation of this small and isolated population of red deer.

Uneven drying of zygotic embryos and embryonic axes of recalcitrant seeds: Challenges and considerations for cryopreservation

Cryopreservation is the most promising option for the long-term germplasm conservation of recalcitrant-seeded species. However, the variable post-cryo success achieved with the excised zygotic explants traditionally used for cryopreservation has been a concern for some time. Differential drying rates amongst explants of different species, uneven drying amongst explants within a batch of seeds and uneven drying across tissues within individual embryos could be contributory factors to this variable success and these phenomena form the foci of the present study. Using zygotic explants from a range of recalcitrant-seeded species, which included sub-tropical dicotyledonous trees and sub-tropical monocotyledonous geophytes, the study showed that embryo morphology and anatomy are critical determinants of the drying characteristics of the different tissues composing the explant and hence, post-cryo survival. The results suggest that the rates of drying of explants to water contents (WCs) in the theoretically optimal range for successful cryopreservation are species-specific, and that more rapid drying rates may promote post-cryo survival. However, the large variation in WC amongst individual explants in bulk samples challenges the selection of the theoretically optimum WC for cryopreservation. As a consequence of differential drying rates across the different tissues composing explants, either lethal ice crystal damage or desiccation damage may sometimes be likely in tissues responsible for the onwards development of the embryo. Drying times for cryopreservation of such explants should, therefore, be selected on the basis of WC of segments containing root or shoot meristem, rather than embryo bulk WC. Drying intensity and duration also interact with explant morphology and embryo/axis size and anatomy to bring about – or preclude – post-cryo survival.

Introducing wood anatomical and dendrochronological aspects of herbaceous plants: applications of the Xylem Database to vegetation science

AbstractObjectivesAlthough more than half of the Earth's landmass is covered by non‐forest vegetation and forests only account for ca. 20%, the majority of wood anatomical and dendrochronological studies still centre on trees and their timber products of secondary meristem growth. Comprehensive assessments of the anatomy, taxonomy, physiology and dendrochronology of herbs are, however, still missing. We therefore aim to evaluate the importance of stem anatomical and dendrochronological aspects of herbaceous plants for vegetation science, and further intend to explore if species‐specific differences in xylem anatomy can be linked with patterns of life form, plant size and site ecology.LocationsNumerous extra‐tropical sites within six biogeographic regions on six continents, spanning an elevational gradient of 4400 m from sea level to the alpine zone.MethodsWe employ the Xylem Database to investigate well‐established and newly defined wood anatomical and dendrochronological traits in 3347 dicotyledonous tree, shrub and herb species from 140 families and 952 genera. The obtained site information is placed in a global context of vegetation cover.ResultsWe demonstrate that plants included in the Xylem Database broadly represent the diversity of growth forms, habitats and life histories of extra‐tropical dicots, thus validating its potential for a range of uses within vegetation science. An unexpectedly rich catalogue of xylem anatomical and dendrochronological features is found in the stems of almost all dwarf shrub and herb species, with the quantity and diversity of their characteristics being comparable to larger plants, including most tree species. Annual rings are formed independently of life form, plant size and site ecology. Secondary growth, which is an expression of plant age, defines the main principle of terrestrial angiosperm development.ConclusionsBased on a first assessment of the Xylem Database, we suggest merging the traditionally separated research communities of wood anatomy and dendrochronology (including dendroclimatology and ‐ecology), as well as expanding their joint application to all non‐forest, extra‐tropical vegetation types. Moreover, we recommend overcoming the theoretical life form separation of trees, shrubs and herbs. This conceptual advancement will likely provide annually resolved insight on the past dynamics of dry matter production and carbon allocation for many marginal vegetation zones beyond the geographic limits of forest growth, which are particularly vulnerable to environmental change. Our study may further stimulate timely efforts in comparing plant morphological and wood anatomical characteristics with phylogenetic reconstructions.

Amazon palm biomass and allometry

Palms (family Arecaceae) are abundant in Amazonian forests, but the allometry of these monocotyledonous plants remains poorly quantified. Woody palm biomass is most commonly estimated with dicotyledonous tree models, which leaves substantial uncertainty as to their true biomass and productivity. We developed the first extensive dataset of directly-measured arborescent palm biomass: 136 individuals from nine species in terra firme and wetland forests — Astrocaryum murumuru, Attalea phalerata, Bactris gasipaes, Euterpe precatoria, Iriartea deltoidea, Mauritia flexuosa, Mauritiella aculeata, Oenocarpus bataua, and Socratea exorrhiza. We created single species (n=8–21) and family-level (n=97–106) allometric equations, using diameter, stem height, total height, and stem dry mass fraction, to estimate (i) total aboveground biomass for all species, (ii) belowground biomass for the two wetland species (Mauritia and Mauritiella), and (iii) leaf mass for all species. These new palm models were then applied to nine 1-ha plots in the southwestern Amazon (Tambopata) to calculate the impact on forest biomass estimates once palm mass is estimated with palm-specific models, rather than from models created for dicot trees. We found that stem height was the best predictor variable for arborescent palm biomass, but the relationship between stem height and biomass differed among species. Most species showed weak biomass–diameter relationships, but a significant relationship could be identified across all species. The new palm models were better estimators of palm mass than existing dicot models. Using our species-level models increased estimates of palm biomass at our study site by 14–27%, compared to using recently published pantropical biomass models for trees. In other forests, the effect of using these palm equations on biomass estimates will depend on palm sizes, abundance, and species composition.

Allometric relationships of frequently used shade tree species in cacao agroforestry systems in Sulawesi, Indonesia

Shade trees play an important role within agroforestry systems by influencing radiation and wind regimes as well as nutrient and hydrological cycling. However, there is a lack of quantitative assessments of their functions. One of the reasons is the rare information on structural characteristics of shade tree species. Therefore, the aim of this study is to provide basic information on the structure of frequently used shade tree species for the implementation of models simulating the ecosystem processes in agroforestry systems. The investigation of the shade trees was conducted at two cacao agroforestry sites on Sulawesi, Indonesia. The measurements of the main structural parameters: diameter at breast height, tree height, trunk height, crown length and crown radius were carried out for the shade tree species Aleurites moluccana, Cocos nucifera and Gliricidia sepium. For data collection, the National Forest Inventory Field Manual Template by FAO (2004) was applied. Based on this information allometric functions were derived for the correspondent shade tree species. The best significant relationships were obtained for the height-crown length relationship of the dicotyledonous tree species’ A. moluccana and G. sepium with a coefficient of determination r² = 0.925 and r² = 0.738, respectively, and the height-crown length relationship of the monocotyledonous palm C. nucifera with r² = 0.663. The transferability tests ‘analysis of covariance’ and ‘homogeneity of slopes’ have shown that the obtained allometric functions are also applicable to other cacao agroforestry systems of the region.

A comparison of the hydraulic efficiency of a palm species (Iriartea deltoidea) with other wood types

Palms are an important component of tropical ecosystems, living alongside dicotyledonous trees, even though they have a very different growth pattern and vascular system. As monocots, vessels in palms are located within vascular bundles and, without a vascular cambium that many dicotyledonous trees possess, palms cannot add additional vessels to their vascular system as they get older and taller. This means that hydraulic architecture in palms is more predetermined, which may require a highly efficient hydraulic system. This preset nature, along with the decoupling of hydraulic and mechanical functioning to different cell types, may allow palms to have a more efficient hydraulic system than dicotyledonous trees. Therefore, this study seeks to determine the efficiency of the hydraulic system in the palm Iriartea deltoidea (Ruiz & Pav.) and compare this efficiency with other tree forms. We measured cross-sectional areas of roots, stems and fronds as well as leaf areas of I. deltoidea saplings. Likewise, cross-sections were made and vessel diameters and frequencies measured. This allowed for the calculation of theoretical specific conductivity (K(S,calc)), theoretical leaf-specific conductivity (K(L,calc)), and vessel diameter and vessel number ratios between distal and proximal locations in the palms. Iriartea deltoidea palms were found to have the largest, least frequent vessels that diverged most from the square packing limit (maximum number of vessels that fit into a given area) compared with other major tree forms, and they therefore invested the least space and carbon into water transport structures. Likewise, conduits tapered by ∼1/3 between ranks (root, bole and petiole), which represents an efficient ratio with regard to the trade-offs between safety and efficiency of the conducting system. Conduits also exhibited a high conservation of the sum of the conduit radii cubed (Σr(3)) across ranks, thereby approximating Murray's law patterning. Therefore, our results indicate that the palm I. deltoidea has a very efficient hydraulic system in terms of maintaining a large conducting capacity with a minimal vascular investment. This efficiency may allow palms to compete well with dicotyledonous trees in tropical and subtropical climates but other developmental factors largely restrict palms from regions that experience prolonged freezing temperatures.

Fungal communities of symptomless bark of tropical trees

The fungi associated with the bark (phellophytes) of fifteen dicotyledonous tree species of a dry thorn, dry deciduous and a stunted montane evergreen forest of the Western Ghats, southern India, were studied. The species diversity of the phellophytes was higher for the montane evergreen forest when compared with dry thorn and dry deciduous forests. Although many fungal species were present in the bark of different tree species, most of them had a low frequency of isolation and only a few were isolated with high frequencies. Species of Phoma and Phomopsis, Fusarium and Paecilomyces and sterile forms EGS1 and EGS3 were isolated with high frequency from dry thorn, dry deciduous and a stunted montane evergreen forest respectively. The dry thorn and dry deciduous forests, which are more arid and fire-prone, shared more phellophyte species than the dry deciduous and montane evergreen forests. The phellophyte assemblages of the different forests were distinct while those of six tree species of a family from one forest showed a high overlap. It appears that the environment, rather than the tree species, determines the phellophyte assemblage in these forests.