Dispersal of Goeppertia marantifolia clonal offspring increases with greater canopy openness and larger plant size

2017 ◽  
Vol 33 (2) ◽  
pp. 107-113 ◽  
Author(s):  
David P. Matlaga ◽  
Rachel K. Snyder ◽  
Carol C. Horvitz
Keyword(s):  
Leaf Area ◽  
Light Availability ◽  
Plant Size ◽  
Dispersal Distance ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Parent Plant ◽  
Analysis Model ◽  
Corcovado National Park ◽  
Positive Effect

Abstract:Many plants within the neotropical understorey produce both seeds and clonal offspring. Plant attributes (i.e. size) and variability in light can influence seed dispersal but it is not known if these factors influence the dispersal of clonal offspring. Our goal was to determine if canopy openness and plant size influence clonal-offspring dispersal of the herb Goeppertia marantifolia, which produces clonal bulbils on above-ground shoots. We monitored plants in permanent plots with varying levels of canopy openness in Corcovado National Park, Costa Rica. We recorded canopy openness, leaf area and the distance clonal offspring travelled from their parent plant (N = 283). Our path analysis model demonstrated that canopy openness had a strong positive effect on dispersal distance, while the association between clonal-offspring dispersal distance and parent plant leaf area was only weakly positive. On average, plants experiencing high canopy openness dispersed their clonal offspring further than plants under low canopy openness (124 cm vs. 79 cm, respectively). Contrary to studies on species that utilize rhizomes and stolons for clonal reproduction, we found that in this bulbil-producing species light availability is positively associated with clonal dispersal distance. Therefore, the influence of resource availability on spatial population dynamics of clonal species may be influenced by the species’ growth-form.

scholarly journals Zero-inflated-censored Weibull and gamma regression models to estimate wild boar population dispersal distance

2021 ◽  
Author(s):  
Eduardo de Freitas Costa ◽  
Silvana Schneider ◽  
Giulia Bagatini Carlotto ◽  
Tainá Cabalheiro ◽  
Mauro Ribeiro de Oliveira Júnior
Keyword(s):  
Wild Boar ◽  
Regression Models ◽  
Likelihood Function ◽  
Complex Structure ◽  
Dispersal Distance ◽  
Wild Boar Population ◽  
Gamma Distributions ◽  
Excess Of Zeros ◽  
Censored Observations ◽  
Positive Effect

AbstractThe dynamics of the wild boar population has become a pressing issue not only for ecological purposes, but also for agricultural and livestock production. The data related to the wild boar dispersal distance can have a complex structure, including excess of zeros and right-censored observations, thus being challenging for modeling. In this sense, we propose two different zero-inflated-right-censored regression models, assuming Weibull and gamma distributions. First, we present the construction of the likelihood function, and then, we apply both models to simulated datasets, demonstrating that both regression models behave well. The simulation results point to the consistency and asymptotic unbiasedness of the developed methods. Afterwards, we adjusted both models to a simulated dataset of wild boar dispersal, including excess of zeros, right-censored observations, and two covariates: age and sex. We showed that the models were useful to extract inferences about the wild boar dispersal, correctly describing the data mimicking a situation where males disperse more than females, and age has a positive effect on the dispersal of the wild boars. These results are useful to overcome some limitations regarding inferences in zero-inflated-right-censored datasets, especially concerning the wild boar’s population. Users will be provided with an R function to run the proposed models.

scholarly journals Quantifying Understory Complexity in Unmanaged Forests Using TLS and Identifying Some of Its Major Drivers

2021 ◽  
Vol 13 (8) ◽  
pp. 1513
Author(s):  
Dominik Seidel ◽  
Peter Annighöfer ◽  
Christian Ammer ◽  
Martin Ehbrecht ◽  
Katharina Willim ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Structural Equation Models ◽  
Light Availability ◽  
Structural Complexity ◽  
Basal Area ◽  
Ecosystem Functions ◽  
Canopy Openness ◽  
Seasonal Precipitation ◽  
Wide Range ◽  
Precipitation And Temperature

The structural complexity of the understory layer of forests or shrub layer vegetation in open shrublands affects many ecosystem functions and services provided by these ecosystems. We investigated how the basal area of the overstory layer, annual and seasonal precipitation, annual mean temperature, as well as light availability affect the structural complexity of the understory layer along a gradient from closed forests to open shrubland with only scattered trees. Using terrestrial laser scanning data and the understory complexity index (UCI), we measured the structural complexity of sites across a wide range of precipitation and temperature, also covering a gradient in light availability and basal area. We found significant relationships between the UCI and tree basal area as well as canopy openness. Structural equation models (SEMs) confirmed significant direct effects of seasonal precipitation on the UCI without mediation through basal area or canopy openness. However, annual precipitation and temperature effects on the UCI are mediated through canopy openness and basal area, respectively. Understory complexity is, despite clear dependencies on the available light and overall stand density, significantly and directly driven by climatic parameters, particularly the amount of precipitation during the driest month.

scholarly journals Similar understorey structure in spite of edaphic and floristic dissimilarity in Amazonian forests

2015 ◽  
Vol 45 (4) ◽  
pp. 393-404 ◽  
Author(s):  
Lassi SUOMINEN ◽  
Kalle RUOKOLAINEN ◽  
Timo PITKÄNEN ◽  
Hanna TUOMISTO
Keyword(s):  
Satellite Imagery ◽  
Forest Structure ◽  
Satellite Image ◽  
Light Availability ◽  
Floristic Composition ◽  
Structural Features ◽  
Canopy Openness ◽  
Understorey Plants ◽  
Amazonian Forests ◽  
Geological Formations

Forest structure determines light availability for understorey plants. The structure of lowland Amazonian forests is known to vary over long edaphic gradients, but whether more subtle edaphic variation also affects forest structure has not beenresolved. In western Amazonia, the majority of non-flooded forests grow on soils derived either from relatively fertile sediments of the Pebas Formation or from poorer sediments of the Nauta Formation. The objective of this study was to compare structure and light availability in the understorey of forests growing on these two geological formations. We measured canopy openness and tree stem densities in three size classes in northeastern Peru in a total of 275 study points in old-growth terra firme forests representing the two geological formations. We also documented variation in floristic composition (ferns, lycophytes and the palm Iriartea deltoidea) and used Landsat TM satellite image information to model the forest structural and floristic features over a larger area. The floristic compositions of forests on the two formations were clearly different, and this could also be modelled with the satellite imagery. In contrast, the field observations of forest structure gave only a weak indication that forests on the Nauta Formation might be denser than those on the Pebas Formation. The modelling of forest structural features with satellite imagery did not support this result. Our results indicate that the structure of forest understorey varies much less than floristic composition does over the studied edaphic difference.

scholarly journals Size-dependent allocation of biomass to ancillary versus flowers of the inflorescences of the epiphyte Tillandsia stricta Soland (Bromeliaceae)

2009 ◽  
Vol 23 (1) ◽  
pp. 130-135 ◽  
Author(s):  
André Mantovani ◽  
Ricardo Rios Iglesias
Keyword(s):  
Leaf Area ◽  
Plant Species ◽  
Vegetative Growth ◽  
Reproductive Investment ◽  
Plant Size ◽  
Reproductive Allocation ◽  
Heterogeneous Environment ◽  
Plant Resources ◽  
Total Leaf Area ◽  
Size Dependent

The amount of resources invested in reproduction is closely correlated to plant size. However, the increase in reproductive investment is not always proportional to the increase in vegetative growth, as the proportion of plant resources allocated to reproduction can increase, decrease or be maintained along different plant sizes. Although comprising thousand of species, epiphytes are poorly studied in relation to reproductive allocation (RA). We describe the variation in the RA of the epiphytic bromeliad Tillandsia stricta Soland with increasing plant sizes. Our goal is not only to evaluate the RA of the whole inflorescence but also quantify the contribution of ancillary structures in the final RA of this plant species. With increasing sizes of T. stricta the reproductive allocation of biomass to the whole inflorescence decreased significantly along plant sizes from 37% to 12%. Reproductive allocation to ancillary and to flowers decreased respectively from 30% to 9% and 10% to 3%. As leaves are the main source of water and nutrients absorption in atmospheric Tillandsia, the total leaf area and area per leaf were used as indicators of foraging capacity, that also increased with plant size. We discuss these results with respect to the capacity of T. stricta to reproduce in the heterogeneous environment of the canopies.

Elevational gradients of bryophyte diversity, life forms, and community assemblage in the southern Appalachian Mountains

2010 ◽  
Vol 40 (11) ◽  
pp. 2164-2174 ◽  
Author(s):  
Sarah E. Stehn ◽  
Christopher R. Webster ◽  
Janice M. Glime ◽  
Michael A. Jenkins
Keyword(s):  
Community Composition ◽  
Elevation Gradient ◽  
Light Availability ◽  
Basal Area ◽  
Life Forms ◽  
High Elevation ◽  
Canopy Openness ◽  
Fine Scale ◽  
Elevational Gradients ◽  
Community Assemblage

We investigated the influence of fine-scale elevational gradients and overstory disturbance on bryophyte distribution, diversity, and community composition. Bryophyte species cover and richness were sampled across 60 randomly selected plots within high-elevation spruce–fir ( Picea – Abies ) forests of Great Smoky Mountains National Park. Ordination and regression analyses revealed a fine-scale elevation gradient (700 m) in bryophyte community composition. Observed changes in bryophyte diversity and community composition were also associated with variation in deciduous basal area and thus litter composition, the prevalence of herbaceous plants, and the degree of canopy openness resulting from balsam woolly adelgid ( Adelges piceae Ratz.) infestation. Although overstory disturbances, such as those caused by the adelgid, create suitable substrate for bryophyte colonization, the corresponding increase in light availability and deciduous basal area may alter bryophyte diversity and community assemblages.

scholarly journals FLAME RETARDANTS EFFECTS ON THE INITIAL GROWTH OF Schizolobium amazonicum HUBER EX DUCKE

2021 ◽  
Vol 45 ◽  
Author(s):  
Elen Silma Oliveira Cruz Ximenes ◽  
Andréa Carvalho da Silva ◽  
Adilson Pacheco de Souza ◽  
Josiane Fernandes Keffer ◽  
Alison Martins dos Anjos ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Leaf Area ◽  
Flame Retardants ◽  
Biomass Accumulation ◽  
Dry Mass ◽  
Initial Growth ◽  
Environmental Implications ◽  
Leaf Dry Mass ◽  
Height Increase ◽  
Positive Effect

ABSTRACT Flame retardants are efficient in fighting wildfire; however, their environmental implications, especially regarding the vegetation, need to be clarified. This work aimed at assessing the effects of flame retardant on the initial growth of Schizolobium amazonicum. Treatments consisted in applying different flame retardant concentrations via substrate and leaf: Phos-Chek WD-881® (0, 3.00, 6.00, 8.00 and 10.00 mL L-1), Hold Fire® (0, 7.00, 9.00, 12.00 and 15.00 mL L-1) and water-retaining polymer Nutrigel® used as alternative retardant (0, 0.25, 0.50, 0.75 and 1.00 g L-1). Growth analyses were carried out to assess the effects of these substances (10 repetitions per treatment). The aliquot of 10.00 mL L-1 of Phos-Chek WD881 applied on the leaves led to an increase of 70% in leaf area and 15% in seedling height. The same Phos-Chek concentration favored height increase (32%) and total dry mass accumulation (33%) throughout time. The concentration of 15 mL L-1 of Hold Fire® applied on leaves, compromised 45% the accumulation of dry biomass in the seedling. Initially, 1.00 g L-1 of Nutrigel® applied via substrate led to an increase of 70% in leaf area, 29% in plant height, and 89% in leaf dry mass. Therefore, Phos-Chek applied on leaves favored shoot growth in S. amazonicum. Hold Fire® applied on leaves impaired biomass accumulation in seedlings. Nutrigel® applied on substrate does not cause long-lasting damage to the initial growth of S. amazonicum. The aliquot of 0.50 g L-1 administered via polymer leave had positive effect on seedling shoot.

scholarly journals TATA KELOLA, KOMPENSASI CEO, KARAKTERISTIK CEO, ACCOUNTING IRREGULARITIES DAN TAX AGGRESSIVENESS

2019 ◽  
Vol 6 (2) ◽  
pp. 285
Author(s):  
Ririn Juliawaty ◽  
Christina Dwi Astuti
Keyword(s):  
Corporate Governance ◽  
Ceo Compensation ◽  
Stock Exchange ◽  
Secondary Data ◽  
Analysis Model ◽  
Tax Aggressiveness ◽  
Ceo Tenure ◽  
Negative Effect ◽  
Independent Variable ◽  
Positive Effect

<p><em>The purpose of this research is</em><em> </em><em>to examine the effect of corporate governance, CEO characteristic, CEO compensation, and accounting irregularities on tax aggressiveness. The dependent variable in this research is tax aggressiveness, while the independent variable in this research are corporate governance, characteristic CEO and CEO compensation</em><em>.</em></p><p><em>This study used secondary data with entire population manufacture companies listed at the Indonesia Stock Exchange (BEI) for 2015 -2017. The research sample are consists of 37 companies. The sampling method used to determine the sample is purposive sampling. The analysis model used in this research is multiple regression of panel data.</em><em></em></p><p><em>Based on analytical results concluded that independent director have a significant and negative effect on tax aggressiveness while accounting irregularities has a significant and positive effect on tax aggressiveness. The board size, CEO compensation, age, and CEO tenure have no significant effect on tax aggressiveness. </em></p>

scholarly journals Edge effects alter the role of fungi and insects in mediating functional composition and diversity of seedling recruits in a fragmented tropical forest

2020 ◽  
Vol 126 (7) ◽  
pp. 1181-1191
Author(s):  
Meghna Krishnadas ◽  
Kavya Agarwal ◽  
Liza S Comita
Keyword(s):  
Tropical Forest ◽  
Functional Diversity ◽  
Seed Size ◽  
Wood Density ◽  
Edge Effects ◽  
Seedling Recruitment ◽  
Light Availability ◽  
Canopy Openness ◽  
Dry Matter Content ◽  
Forest Fragments

Abstract Background and Aims In fragmented forests, proximity to forest edges can favour the establishment of resource-acquisitive species over more resource-conservative species. During seedling recruitment, resource-acquisitive species may benefit from either higher light availability or weaker top-down effects of natural enemies. The relative importance of light and enemies for recruitment has seldom been examined with respect to edge effects. Methods In a human-modified wet tropical forest in India, we first examined how functional traits indicative of resource-acquisitive vs. resource-conservative strategies, i.e. specific leaf area (SLA), leaf dry matter content, wood density and seed size, explained interspecific differences in densities of seedling recruits with distance to the forest edge. Then, we checked whether fungicide and insecticide treatments and canopy openness (proxy for light availability) explained edge effects on trait-mediated changes in seedling density. Finally, we examined whether light availability and natural enemy activity explained edge effects on functional diversity of seedling recruits. Key Results Up to 60 m from edges, recruit densities increased with decreasing seed size, but not at 90–100 m, where recruit densities increased with higher SLA. Trait-mediated variation in recruit densities changed with pesticides only at 90–100 m: compared with control plots, fungicide increased recruit densities for low SLA species and insecticide increased smaller seeded species. For SLA, wood density and seed size, functional diversity of recruits was higher at 90–100 m than at 0–5 m. At 90–100 m, fungicide decreased functional diversity for SLA and insecticide reduced seed size diversity compared with control plots. Canopy openness explained neither variation in recruit density in relation to traits nor functional diversity. Conclusions Altered biotic interactions can mediate local changes to trait composition and functional diversity during seedling recruitment in forest fragments, hinting at downstream effects on the structure and function of human-modified forests.

scholarly journals The effect of light availability on leaf area index, biomass production and plant species composition of park grasslands in Warsaw  

2013 ◽  
Vol 59 (No. 12) ◽  
pp. 543-548 ◽  
Author(s):  
P. Dąbrowski ◽  
B. Pawluśkiewicz ◽  
Kalaji HM ◽  
Baczewska AH
Keyword(s):  
Solar Radiation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Light Availability ◽  
Vegetation Coverage ◽  
Light Conditions ◽  
Area Index ◽  
Sward Height ◽  
Poa Trivialis ◽  
Leaf Density

How light conditions affect development of park grasslands is a question that has not been satisfactory addressed. The aim of this study was therefore determination of the level to which unfavorable light conditions influence grassy parks area and relationships between parameters which determine state of turf grasses. Researches were conducted in two parks in Warsaw, in various light conditions and included measurement of: leaf density, sward height, leaf area index (LAI), and botanical composition of the communities. The leaf density of shaded areas did not exceed 70%. LAI value varied from 0.5 to 0.9-fold lower than in the areas in half-shade and in sun. The participation of basic lawn species at Skaryszewski Park was higher under shade, while at Łazienki Kr&oacute;lewskie was higher in full-sunlight areas. The state of tested grassy areas in limited solar radiation does not satisfy the requirements of recreational and representational functions. The development processes of vegetation coverage were inhibited at the sites of lower solar radiation. LAI was influenced by both leaf coverage and sward height. Agrostis stolonifera and Poa trivialis may be recommended to create grass areas under limited solar radiation.

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