scholarly journals Seed biometry: another functional trait in caatinga

2020 ◽  
Vol 42 ◽  
pp. e51183
Author(s):  
Marcelo da Costa Patrício ◽  
Dilma Maria de Brito Melo Trovão
Keyword(s):  
Functional Trait ◽  
Environmental Stresses ◽  
Pioneer Species ◽  
Environmental Filters ◽  
Essential Condition ◽  
Seed Collection ◽  
Vector Type ◽  
Nutrient Reserve ◽  
Length Width ◽  
Successional Stages

Seed biometrics is an excellent tool for understanding environmental filters, species potential and dispersal, successional stages of communities and the dynamics used by seeds to germinate, establish and develop, thus constituting a functional trait of the species. We aim to understand the relationship between aspects of seed biometrics and other phenological traits, in order to infer contributions about functional strategies in Caatinga. Between September 2017 and January 2019, 10 individuals of Cenostigma pyramidale (Tul.) LP Queiroz, Commiphora lepthophloeos (Mart.) JB Gillett, Jatropha mollissima (Pohl.) Baill., Monteverdia rigida (Mart.) Biral. Pseudobombax marginatum (A.ST.-Hil) A. Robyns, Zizyphus joazeiro Mart. were monitored for the selection of three seed collection matrices. From each matrix 100 seeds were collected, which after screening resulted in 35 intact seeds that were used to measure length, width, thickness and volume. Caatinga seeds are generally small, as a result of the environmental stresses of the Brazilian semiarid. The analyzed variables separated three groups in the PCA. We noticed that these groups evidenced the successional stages in the Caatinga. One group included M. rigida and P. marginatum, which are late secondary. C. pyramidale and C. lepthophloeos formed another group coincident with intermediate successional stages. J. mollissima and Z. joazeiro formed a group of pioneer species in anthropized environments. Another finding was that the area was in secondary succession. The pioneer species presented the largest seeds and this characteristic is associated with the need for nutrient reserve that allows the embryo to germinate and last for a longer period without the need for exogenous nutrients, an essential condition for the Caatinga. With the advancement of ecological succession and the establishment of a more consolidated plant community, competition for resources, the frequent dispersion vector type and the nature of the environmental stresses present, the seeds may be smaller.

scholarly journals PHYSICAL AND CHEMICAL DEFENSES OF Cenostigma pyramidale (FABACEAE): A PIONEER SPECIES IN SUCCESSIONAL CAATINGA AREAS

2021 ◽  
Vol 34 (2) ◽  
pp. 398-409
Author(s):  
IZABELLA MARIA CINTRA RIBEIRO ◽  
EMILIA CRISTINA PEREIRA DE ARRUDA ◽  
ANTONIO FERNANDO MORAIS DE OLIVEIRA ◽  
JARCILENE SILVA DE ALMEIDA
Keyword(s):  
Chemical Defenses ◽  
Total Phenolic ◽  
Pioneer Species ◽  
Secretory Structures ◽  
Successional Stage ◽  
Successional Stages ◽  
The Difference ◽  
Physical And Chemical ◽  
Wax Load ◽  
Phenolics Compounds

ABSTRACT Cenostigma pyramidale, a pioneer species presents in all different successional stage (early, intermediate and late) of fifteen natural regeneration areas of Caatinga after land used changed and abandonment was used to investigates the morphological and physiological attributes that are very important to xeromorphic conditions as against herbivories. Leaf samples were collected to evaluate the percentage of the herbivory and index of sclerophylly. Anatomy, histochemistry, total phenolic content, epicuticular wax load, and n-alkanes profile were also performed. The results showed an inverse relationship between the percentage of herbivory and the index of sclerophylly. The leaves showed typical morphological and anatomical characteristics of xeric environments plants such as uniseriate epidermis and trichomes. Furthermore, it was also noticed a decrease in the overall thickness and the tissues according to the advancement of the successional stages. The histochemical revealed the presence of lipidic substances coating the epidermal layers, phenolics compounds stored in secretory structures, and starch in the mesophyll. The concentration of phenolics compounds indicating the difference from health leaves of plants between different stages of regeneration, but no difference when they were herbivored. The amount of cuticle wax did not change significantly with the successional stage. The profile of n-alkanes was characterized by the predominance of nonacosane (C29) and hentriacontane (C31). The C29 content decreases with the advancement of the successional stage, while the C31 content increases. All those attributes have a role to protect the plants to acclimate to the various environmental conditions of Caatinga.

Fruit and Seed Development of Sorbus pohuashanensis Hedl

2011 ◽  
Vol 393-395 ◽  
pp. 772-775
Author(s):  
Ling Yang ◽  
Yu Hua Li ◽  
Hai Long Shen
Keyword(s):  
Seed Development ◽  
Additional Data ◽  
Developmental Stages ◽  
Dry Weight ◽  
Significant Negative Correlation ◽  
Width Ratio ◽  
Seed Collection ◽  
Embryo Formation ◽  
Length Width ◽  
Embryo Length

Seed development traits of Sorbus pohuashanensis are discussed with special regard to embryo formation. The purpose of this research was to provide additional data for understanding embryo developmental processes and identifying the appropriate developmental stage for seed collection in S. pohuashanensis. A correlation was found between the embryo developmental stages and the time after pollination. The developmental stages cover globular, heart, torpedo and cotyledonary embryo stages within 30 days post-pollination. There were significant differences in embryo length, width and length to width ratio at different development stages. A significant negative correlation between embryo dry weight (DW) and moisture content (MC) was also observed.

scholarly journals Comparing the Influence of Assembly Processes Governing Bacterial Community Succession Based on DNA and RNA Data

2020 ◽  
Vol 8 (6) ◽  
pp. 798 ◽  
Author(s):  
Xiu Jia ◽  
Francisco Dini-Andreote ◽  
Joana Falcão Salles
Keyword(s):  
Variable Selection ◽  
Environmental Variability ◽  
Null Model ◽  
Relative Influence ◽  
Environmental Filters ◽  
Rna Transcripts ◽  
Dna And Rna ◽  
Α Diversity ◽  
Community Outcomes ◽  
Successional Stages

Quantifying which assembly processes structure microbiomes can assist prediction, manipulation, and engineering of community outcomes. However, the relative importance of these processes might depend on whether DNA or RNA are used, as they differ in stability. We hypothesized that RNA-inferred community responses to (a)biotic fluctuations are faster than those inferred by DNA; the relative influence of variable selection is stronger in RNA-inferred communities (environmental factors are spatiotemporally heterogeneous), whereas homogeneous selection largely influences DNA-inferred communities (environmental filters are constant). To test these hypotheses, we characterized soil bacterial communities by sequencing both 16S rRNA amplicons from the extracted DNA and RNA transcripts across distinct stages of soil primary succession and quantified the relative influence of each assembly process using ecological null model analysis. Our results revealed that variations in α-diversity and temporal turnover were higher in RNA- than in DNA-inferred communities across successional stages, albeit there was a similar community composition; in line with our hypotheses, the assembly of RNA-inferred community was more closely associated with environmental variability (variable selection) than using the standard DNA-based approach, which was largely influenced by homogeneous selection. This study illustrates the need for benchmarking approaches to properly elucidate how community assembly processes structure microbial communities.

scholarly journals Spatial and temporal dynamics of growth of woody plant species (birch and willows) on the foreland of a retreating glacier in southern Iceland

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Haley E. Synan ◽  
Mikael A. Melfi ◽  
Lawrence H. Tanner
Keyword(s):  
Plant Species ◽  
Woody Plant ◽  
Temporal Dynamics ◽  
Statistical Significance ◽  
Temporal Distribution ◽  
Conclusive Evidence ◽  
Individual Species ◽  
Environmental Filters ◽  
Woody Plant Species ◽  
Successional Stages

Abstract Background The forelands of retreating glaciers are invaluable natural laboratories in which to explore the processes of primary succession. Numerous studies have been conducted on foreland chronosequences to identify temporal and spatial trends of the successional communities. This study focused on the spatio-temporal distribution of three woody plant species on the foreland of a retreating glacier in southern Iceland where historical observations provide precise age control of the moraines. To evaluate colonization and successional trends, we examined which species increase in abundance with time and tested the role of proximity to a seed source in colonization. Additionally, we quantified the rate at which biomass carbon is added to the landscape. Results The density of stems of Betula pubescens increases with moraine age across the foreland chronosequence while the density of stems of both Salix lanata and Salix phylicifolia decreases. We found low statistical significance to the relationship between the density of B. pubescens and distance from a forested ridge nor did we find a relationship between the lengths of the stems and the moraine ages. Woody biomass increased fastest during early successional stages and reached a maximum of 28.5 g C m− 2 on the oldest moraine. Conclusions Early colonization of moraines was controlled by environmental filters which favored both Salix species. Colonization by B. pubescens followed as environmental factors, e.g., favorable soil properties, improved. We found no conclusive evidence that proximity to a potential source of B. pubescens propagules was a significant factor in controlling colonization. The assumption that the abundance of individuals increased with time through later successional stages proved valid for B. pubescens, but not for either species of Salix. These findings are consistent with the classical spatial successional model of community homogenization. Thus, general successional processes at the landscape scale control the temporal dynamics of individual species.

Direct structure images of 30° partial dislocation cores in silicon

1987 ◽  
Vol 45 ◽  
pp. 242-243
Author(s):  
J. C. Barry ◽  
H. Alexander
Keyword(s):  
Dislocation Core ◽  
Preparation Technique ◽  
Burgers Vector ◽  
Vector Type ◽  
Sample Preparation Technique ◽  
Lattice Images ◽  
Dislocation Core Structure ◽  
Type Lattice ◽  
Direct Inspection

Dislocations in silicon produced by plastic deformation are generally dissociated into partials. 60° dislocations (Burgers vector type 1/2[101]) are dissociated into 30°(Burgers vector type 1/6[211]) and 90°(Burgers vector type 1/6[112]) dislocations. The 30° partials may be either of “glide” or “shuffle” type. Lattice images of the 30° dislocation have been obtained with a JEM 100B, and with a JEM 200Cx. In the aforementioned experiments a reasonable but imperfect match was obtained with calculated images for the “glide” model. In the present experiment direct structure images of 30° dislocation cores have been obtained with a JEOL 4000EX. It is possible to deduce the 30° dislocation core structure by direct inspection of the images. Dislocations were produced by compression of single crystal Si (sample preparation technique described in Alexander et al.).

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

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