scholarly journals Within-Site Variability of Liana Wood Anatomical Traits: A Case Study in Laussat, French Guiana

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 523 ◽  
Author(s):  
Félicien Meunier ◽  
Sruthi M. Krishna Moorthy ◽  
Hannes P. T. De Deurwaerder ◽  
Robin Kreus ◽  
Jan Van den Bulcke ◽  
...  
Keyword(s):  
Specific Gravity ◽  
French Guiana ◽  
Growth Form ◽  
Vessel Diameter ◽  
Small Sample ◽  
Diameter Distribution ◽  
Hydraulic Architecture ◽  
Woody Vines ◽  
Wood Trait ◽  
The Individual

Research Highlights: We investigated the variability of vessel diameter distributions within the liana growth form among liana individuals originating from a single site in Laussat, French Guiana. Background and Objectives: Lianas (woody vines) are key components of tropical forests. Lianas are believed to be strong competitors for water, thanks to their presumed efficient vascular systems. However, unlike tropical trees, lianas are overlooked in field data collection. As a result, lianas are often referred to as a homogeneous growth form while little is known about the hydraulic architecture variation among liana individuals. Materials and Methods: We measured several wood hydraulic and structural traits (e.g., basic specific gravity, vessel area, and vessel diameter distribution) of 22 liana individuals in a single sandy site in Laussat, French Guiana. We compared the liana variability of these wood traits and the correlations among them with an existing liana pantropical dataset and two published datasets of trees originating from different, but species-rich, tropical sites. Results: Liana vessel diameter distribution and density were heterogeneous among individuals: there were two orders of magnitude difference between the smallest (4 µm) and the largest (494 µm) vessel diameters, a 50-fold difference existed between extreme vessel densities ranging from 1.8 to 89.3 vessels mm−2, the mean vessel diameter varied between 26 µm and 271 µm, and the individual theoretical stem hydraulic conductivity estimates ranged between 28 and 1041 kg m−1 s−1 MPa−1. Basic specific gravity varied between 0.26 and 0.61. Consequently, liana wood trait variability, even within a small sample, was comparable in magnitude with tree surveys from other tropical sites and the pantropical liana dataset. Conclusions: This study illustrates that even controlling for site and soil type, liana traits are heterogeneous and cannot be considered as a homogeneous growth form. Our results show that the liana hydraulic architecture heterogeneity across and within sites warrants further investigation in order to categorize lianas into functional groups in the same way as trees

scholarly journals Fine-scale mapping of sapwood anatomical properties reveals plasticity in hydraulics during water deficit

2015 ◽  
Vol 2 ◽  
pp. e003 ◽  
Author(s):  
Patrick J. Mitchell ◽  
Dale Worledge
Keyword(s):  
Water Deficit ◽  
Water Availability ◽  
Vessel Diameter ◽  
Growth Responses ◽  
Hydraulic Architecture ◽  
Environmental Controls ◽  
Wall Strength ◽  
Anatomical Properties ◽  
The Individual ◽  
Response To Water

Growth responses to water deficit translate into discernible changes in the structure of woody tissues and provide an integrated record of historical water availability throughout the life of the individual. The highly dynamic nature of woody growth can impart adaptive changes in physiological performance through changes in xylem elements that regulate water transport. Here, we present a case study of how sapwood anatomical properties can be mapped using point dendrometers, in a diffuse porous, Eucalyptus spp. to reveal plasticity in hydraulic architecture under water deficit. Reductions in stem growth in response to water deficit coincided with marked changes sapwood vessel anatomy that could be matched to the commencement of large fluctuations in stem radius. These changes included: a reduction in hydraulically-weighted vessel diameter, increases in vessel density, sapwood lumen fraction and density and increase in wall strength. However, no changes in estimated stem conductivity were observed during the water deficit. This approach emphasises the responsiveness of species such as Eucalyptus to changes in water supply and provides an illustration of how we might detect short-term and rapid changes in stem hydraulic architecture in response to water availability and other environmental controls.

scholarly journals The comparison of the scores obtained by Bayesian nonparametric model and classical test theory methods

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110283
Author(s):  
Meltem Yurtcu ◽  
Hülya Kelecioglu ◽  
Edward L Boone
Keyword(s):  
Classical Test Theory ◽  
Small Sample ◽  
Test Theory ◽  
Nonparametric Model ◽  
Bayesian Nonparametric ◽  
Test Equating ◽  
Classical Test ◽  
A Value ◽  
Item Functioning ◽  
The Individual

Bayesian Nonparametric (BNP) modelling can be used to obtain more detailed information in test equating studies and to increase the accuracy of equating by accounting for covariates. In this study, two covariates are included in the equating under the Bayes nonparametric model, one is continuous, and the other is discrete. Scores equated with this model were obtained for a single group design for a small group in the study. The equated scores obtained with the model were compared with the mean and linear equating methods in the Classical Test Theory. Considering the equated scores obtained from three different methods, it was found that the equated scores obtained with the BNP model produced a distribution closer to the target test. Even the classical methods will give a good result with the smallest error when using a small sample, making equating studies valuable. The inclusion of the covariates in the model in the classical test equating process is based on some assumptions and cannot be achieved especially using small groups. The BNP model will be more beneficial than using frequentist methods, regardless of this limitation. Information about booklets and variables can be obtained from the distributors and equated scores that obtained with the BNP model. In this case, it makes it possible to compare sub-categories. This can be expressed as indicating the presence of differential item functioning (DIF). Therefore, the BNP model can be used actively in test equating studies, and it provides an opportunity to examine the characteristics of the individual participants at the same time. Thus, it allows test equating even in a small sample and offers the opportunity to reach a value closer to the scores in the target test.

WOOD CHARACTERISTICS OF AMAZON FOREST TYPES

IAWA Journal ◽  
2000 ◽  
Vol 21 (3) ◽  
pp. 277-292 ◽  
Author(s):  
D.W. Woodcock ◽  
G. Dos Santos ◽  
C. Reynel
Keyword(s):  
Specific Gravity ◽  
Vessel Diameter ◽  
Floodplain Forest ◽  
Small Samples ◽  
Vessel Element ◽  
Amazon Forest ◽  
Forest Types ◽  
Swamp Forest ◽  
Climate Controls ◽  
Pattern Of Variation

The Tambopata region of the southern Peruvian Amazon supports a high diversity of both woody plants and forest types. Woods collected from low riverside vegetation, floodplain forest, clay-soil forest on an upper terrace, sandy-soil forest, and swamp forest provide an opportunity to test for significant differences in quantitative anatomical characters among forest types. Vessel-element length in floodplain-forest trees is significantly greater than in the other forest types. Specific gravity is lower in the two early-successional associations (low riverine forest and mature floodplain forest). Vessel diameter and density do not show significant differences among forest types and may be responding to overall climate controls. These two characters, however, show a pattern of variation within a transect extending back from the river along a gradient of increasing substrate and forest age; in addition, sites characterized by frequent flooding or presence of standing water lack vessels in the wider-diameter classes. The six characters analyzed show distributions that are, with the exception of wood specific gravity, significantly nonnormally distributed, a consideration that may be important in representing characteristics of assemblages of taxa. The degree of variability seen in some of the quantitative characters shows the importance of either basing analysis on adequate sample sizes or identifying robust indicators that can be used with small samples.

scholarly journals Diagnostic Challenges in Newborns and Infants with Coagulation Disorders

2020 ◽  
Vol 40 (01) ◽  
pp. 084-087
Author(s):  
Wolfgang Eberl
Keyword(s):  
Children And Adolescents ◽  
Small Sample ◽  
Laboratory Diagnostics ◽  
Coagulation Disorders ◽  
Small Children ◽  
Preanalytical Phase ◽  
Coagulation Tests ◽  
Strategy Performance ◽  
Performance And Evaluation ◽  
The Individual

AbstractLaboratory diagnostics in children and adolescents, especially in newborns and very small children, differ considerably compared with laboratory diagnostics in adults. This applies to all individual steps of the examination (i.e., the indication, the preanalytical phase, the analysis itself, and interpretation of the findings). This is particularly true in the diagnostics of hemostasis, in which small sample volumes and relatively error prone coagulation tests are posing particular challenges to the strategy, performance, and evaluation of the tests. Differences in the individual steps are illustrated below.

Teacher coaching in New Zealand secondary schools: an exploratory study

2019 ◽  
Vol 8 (2) ◽  
pp. 70-85
Author(s):  
Paul Nathan Bennett
Keyword(s):  
New Zealand ◽  
Secondary Schools ◽  
Small Sample Size ◽  
Small Sample ◽  
Social Construct ◽  
Content Type ◽  
Evaluation Strategies ◽  
Development Approach ◽  
The Individual ◽  
Teacher Coaching

Purpose The purpose of this paper is to explore how teacher coaching is being implemented in New Zealand secondary schools. Design/methodology/approach A pragmatic mixed methods approach was identified as the most suitable. A dominant qualitative approach, using a sequential design, incorporating triangulation of methods and perspectives across time, provided an appropriate research design framework. Findings The findings indicate that teacher coaching is a popular professional development approach that has been enthusiastically implemented throughout New Zealand secondary schools. The four factors of purpose, evaluation, training and funding have been shown to be interrelated factors operating in New Zealand teacher coaching programmes. These factors are perceived to have an influence on teacher coaching programmes achieving their stated objectives. Research limitations/implications A limitation of this study is that it provides a snapshot of teacher coaching in New Zealand secondary schools, and the snapshot presented is constantly changing. A methodological limitation of the study related to the 28 per cent response rate of the questionnaire and the small sample size used for the interview phases. Practical implications This study encourages school leaders to consider if they have defined teacher coaching in the context of their programmes and articulated their objectives. They are persuaded to think about how they could design robust evaluation strategies and targeted training. Social implications The findings show the concept of teacher coaching is a social construct that is influenced not only by unique environmental contexts but also the individual perceptions of all those involved. Originality/value This study provides new knowledge in relation to how and why teacher coaching is being used and the factors that influence whether programme objectives are achieved.

scholarly journals Axial anatomy of the leaf midrib provides new insights into the hydraulic architecture and cavitation patterns of Acer pseudoplatanus leaves

2019 ◽  
Vol 70 (21) ◽  
pp. 6195-6201 ◽  
Author(s):  
Silvia Lechthaler ◽  
Pierluigi Colangeli ◽  
Moira Gazzabin ◽  
Tommaso Anfodillo
Keyword(s):  
Leaf Area ◽  
Good Predictor ◽  
Path Length ◽  
Vessel Diameter ◽  
Acer Pseudoplatanus ◽  
Hydraulic Architecture ◽  
Leaf Base ◽  
Embolism Resistance ◽  
Conduit Diameter ◽  
Hierarchical Scheme

Abstract The structure of leaf veins is typically described by a hierarchical scheme (e.g. midrib, 1st order, 2nd order), which is used to predict variation in conduit diameter from one order to another whilst overlooking possible variation within the same order. We examined whether xylem conduit diameter changes within the same vein order, with resulting consequences for resistance to embolism. We measured the hydraulic diameter (Dh), and number of vessels (VN) along the midrib and petioles of leaves of Acer pseudoplatanus, and estimated the leaf area supplied (Aleaf-sup) at different points of the midrib and how variation in anatomical traits affected embolism resistance. We found that Dh scales with distance from the midrib tip (path length, L) with a power of 0.42, and that VN scales with Aleaf-sup with a power of 0.66. Total conductive area scales isometrically with Aleaf-sup. Embolism events along the midrib occurred first in the basipetal part and then at the leaf tip where vessels are narrower. The distance from the midrib tip is a good predictor of the variation in vessel diameter along the 1st order veins in A. pseudoplatanus leaves and this anatomical pattern seems to have an effect on hydraulic integrity since wider vessels at the leaf base embolize first.

Detection of spatial pattern at several scales simultaneously

1975 ◽  
Vol 7 (03) ◽  
pp. 449-450
Author(s):  
Roger Mead
Keyword(s):  
Spatial Pattern ◽  
Plant Communities ◽  
Random Distribution ◽  
Small Sample ◽  
Pattern Detection ◽  
Ecological Research ◽  
Valid Method ◽  
Distributional Properties ◽  
The Individual ◽  
Plant Ecological

Detection of the different scales of pattern in plant communities is an important area of plant ecological research, and various tests of pattern have been devised. The method of pattern detection which is ecologically most meaningful is that due to Greig-Smith (1952) but, until now, this has suffered from the lack of valid tests of significance for the individual scales of pattern, once the overall departure from a random distribution has been established. Various tests which partially or completely overcome this deficiency are discussed and exemplified and their small sample distributional properties examined. It is concluded that a set of tests, based on randomisation arguments, provides a fully valid method of testing simultaneously for pattern at various scales.

Between- and Within-Tree Variation in the Anatomy and Specific Gravity of Wood in Oregon White Oak (Quercus Garryana Dougl.)

IAWA Journal ◽  
1996 ◽  
Vol 17 (4) ◽  
pp. 445-461 ◽  
Author(s):  
Hua Lei ◽  
Michael R. Milota ◽  
Barbara L. Gartner
Keyword(s):  
Specific Gravity ◽  
Pseudotsuga Menziesii ◽  
Fibre Length ◽  
Wood Properties ◽  
Vessel Diameter ◽  
Coast Range ◽  
Quercus Garryana ◽  
White Oak ◽  
Earlywood Vessel ◽  
Oregon White Oak

In order to analyze the variation in wood properties within and between trees of an underutilized tree species, we sampled six Oregon white oak (Quercus garryana Dougl.) trees from an 80-year old mixed stand of Q. garryana and Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in the Coast Range of Western Oregon, USA. Fibre length, earlywood vessel diameter, tissue proportions, and specific gravity were measured on samples across the diameter at two heights. Trees had a slight lean (2-12°), so we sampled separately both radii of a diametric strip that ran from the lower to upper side of lean.

scholarly journals Procedural Predictors for Bioresorbable Vascular Scaffold Thrombosis: Analysis of the Individual Components of the “PSP” Technique

2019 ◽  
Vol 8 (1) ◽  
pp. 93 ◽  
Author(s):  
Zisis Dimitriadis ◽  
Alberto Polimeni ◽  
Remzi Anadol ◽  
Martin Geyer ◽  
Melissa Weissner ◽  
...  
Keyword(s):  
De Novo ◽  
Vessel Diameter ◽  
Expansion Ratio ◽  
Implantation Technique ◽  
Bioresorbable Vascular Scaffold ◽  
Increased Risk ◽  
Scaffold Thrombosis ◽  
Vascular Scaffolds ◽  
The Individual ◽  
The Impact

The technique used at the time of implantation has a central role in determining the risk of thrombosis in bioresorbable vascular scaffolds (BRS). Different definitions of the “optimal” implantation technique exist, however. The impact of individual procedural characteristics on the risk of scaffold thrombosis (ScT) was evaluated in a single-center observational study that enrolled 657 patients (79% males, mean age 63 ± 12 years) with 763 lesions who received a total of 925 BRS for de novo lesions. During a median 1076 (762–1206) days’ follow-up there were 28 cases of thrombosis. Independent predictors of ScT included the use of predilatation balloons bigger than the nominal BRS diameter (hazard ratio (HR) = 0.4 (0.16–0.98), p = 0.04), sizing (implantation in vessels with reference vessel diameter >3.5 mm or <2.5 mm: HR = 5.71 (2.32–14.05), p = 0.0002) and the degree of vessel expansion (ratio of minimum lumen to reference vessel diameter, HR: 0.005 (0.0001–0.23), p = 0.007). In addition, a mild BRS oversizing (final BRS diameter to vessel diameter 1.14–1.28) was associated with a lower thrombosis risk, whereas undersizing and more severe oversizing (final BRS diameter to vessel diameter <1.04 and >1.35, respectively) were associated with an increased risk of ScT (HR = 0.13 (0.02–0.59), p = 0.0007). In conclusion, different components of the “optimal” technique have different impacts on the risk of BRS thrombosis. Besides predilatation with a balloon larger than the BRS diameter, correct vessel size selection and a mild to moderate oversizing appear to be protective.

scholarly journals Longevity of the Brazilian underground tree Jacaranda decurrens Cham.

2013 ◽  
Vol 85 (2) ◽  
pp. 671-678 ◽  
Author(s):  
RUY J.V. ALVES ◽  
NiLBER G. DA SILVA ◽  
ALUiSIO J. FERNANDES JUNIOR ◽  
ALESSANDRA R. GUIMARAES
Keyword(s):  
Endangered Species ◽  
Clonal Growth ◽  
Growth Form ◽  
Branching Pattern ◽  
Brazilian Cerrado ◽  
Crown Diameter ◽  
Clonal Growth Form ◽  
The Mean ◽  
Neotropical Plants ◽  
The Individual

Underground trees are a rare clonal growth form. In this survey we describe the branching pattern and estimate the age of the underground tree Jacaranda decurrens Cham. (Bignoniaceae), an endangered species from the Brazilian Cerrado, with a crown diameter of 22 meters. The mean age calculated for the individual was 3,801 years, making it one of the oldest known living Neotropical plants.

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