scholarly journals Long-Term Changes in Spatial Patterns and Life-Stage Structure in a Population of Senecio umbrosus Waldst. et Kit. Along With the Transformation of Grassland Vegetation

2020 ◽  
Vol 89 (4) ◽  
Author(s):  
Bożenna Czarnecka
Keyword(s):  
Life Stage ◽  
Initial Density ◽  
Floristic Composition ◽  
Stage Structure ◽  
Clustering Coefficient ◽  
Tree Cover ◽  
Island Population ◽  
Litter Cover ◽  
Brachypodium Pinnatum ◽  
Calamagrostis Epigejos

This paper was a part of studies conducted within an island population of the ragwort <em>Senecio umbrosus </em>(White Mt, southeastern Poland), a vulnerable element of xerothermic grasslands. Special attention was paid to the effects of expansive grass encroachment vs. grassland burning episodes on spatiotemporal patterns and life-stage structure of individuals in the population. The population traits were investigated nine times from 1990 to 2010, within three permanent patches differing in soil properties, initial floristic composition, grassland cover (particularly the cover of <em>Brachypodium pinnatum</em>), ragwort cover and density, shrub/tree cover influencing light intensity (full light–shadow), and grassland burning (zero–six episodes). There was a drastic decline in ragwort abundance within all the study patches accompanied by a decrease in the population clustering coefficient and a gradual equalization of the spatial distribution of ramets. The abundance was negatively correlated (PCA analysis) with an increase in <em>B. pinnatum </em>cover and positively correlated with the number of burning episodes, which temporarily delimited persistent litter cover and facilitated recruitment of new individuals. The decrease in ramet abundance ranged from 3.8 times (medium-high, moderately shadowed grassland; six cases of burning) to 8.3 times (high, dense, and shadowed grassland; four cases of burning). The patch of low, loose, sunlit, and never-burned grassland with the greatest initial density of ragwort (a 6.8-fold decrease in abundance) has evolved with time into a high and dense grassland with a greater coverage of <em>B. pinnatum </em>and <em>Calamagrostis epigejos</em>, additionally shaded by shrubs and young trees.

scholarly journals The dynamics of the population of a steppe perennial Senecio macrophyllus M.BIEB. during xerothermic grassland overgrowing

2011 ◽  
Vol 78 (3) ◽  
pp. 247-256 ◽  
Author(s):  
Bożena Czarnecka
Keyword(s):  
Life Stage ◽  
Stage Structure ◽  
Seed Rain ◽  
Island Population ◽  
Reproduction Mode ◽  
Model Object ◽  
Management Regime ◽  
Brachypodium Pinnatum ◽  
The Individual ◽  
Individual Fecundity

The study aimed to determine the long-term changes of the <em>Senecio macrophyllus</em> M.BIEB. population traits: the abundance, reproduction mode, individual fecundity, seed rain and recruitment of new genets in the course of xerothermic grassland overgrowing. The study had also the applied goal: to estimate the chances of "special care" species to survive in the changing environment without management regime for the maintenance of grassland. The model object was the island population of large-leaved ragwort on Biała Góra (the White Mountain) near Tomaszów Lubelski, South-East Poland. To achieve these aims I used the following sets of data: phytosociological relev,s made in plant communities in an interval of 16-18 years; repeated elaboration of the numbers and life-stage structure of the population, both by non-surface and surface method; observation of plants<sup>,</sup> life cycle in 50 labelled genets; population reproduction and seed rain amounts. The area of an open xerothermic grassland decreased due to the process of overgrowing by bushes which was accompanied by the increasing coverage of forest and meadow herbs as well as monocotyledons, mainly <em>Brachypodium pinnatum</em> and <em>Calamagrostis epigejos</em>. The abundance of the <em>S. macrophyllus</em> population noticable diminished. The flowering mode has been changing during years from an oscillation to a chaotic type which caused the significant decreasing of the individual fecundity, population reproduction and seed rain. In last years it was reflected in the interruption of juveniles’ recruitment.

scholarly journals Broadleaved regeneration dynamics in the Pine plantation

2011 ◽  
Vol 57 (No. 10) ◽  
pp. 432-438 ◽  
Author(s):  
K.K. Islam ◽  
S. Patricia ◽  
RinchenY
Keyword(s):  
Vegetation Change ◽  
Pinus Nigra ◽  
Tree Cover ◽  
Pine Plantation ◽  
Explanatory Variables ◽  
Litter Cover ◽  
Significant Difference ◽  
Broadleaved Tree ◽  
Definition Of ◽  
Site Types

&nbsp; In an Island of the Netherlands, Pine (Pinus nigra) was planted to stabilize the dunes and to protect the arable lands from the blowing sand. This research was conducted to understand the most important environmental factors responsible for a vegetation change in the Pine plantation and effect of this change on the rare orchid population: Goodyera repens and Listera cordata. Vegetation sampling was carried out according to the Braun-Blanquet phytosociologic method within the three sites of this Island. Twinspan analysis confirmed the definition of three site types and redundancy analysis showed a significant difference between the pure Pine stands and the plots with regeneration. The results revealed that the most significant explanatory variables were litter cover, broadleaved tree cover, and shrub cover indicating the vegetation change under the Pine plantation. The abundance of Goodyera repens is strongly associated with the Pine forest and negatively related to broadleaved cover. Listera cordata could apparently cope with vegetation change. Controlling the herbaceous layer in the Pine plantation can promote the orchid population but on the contrary, promoting the natural regeneration of broadleaved species might endanger them.

scholarly journals Floristic composition and potential invasiveness of alien herbaceous plant in Western Mexico

2021 ◽  
Vol 69 (3) ◽  
Author(s):  
Isabel Pérez-Postigo ◽  
Heike Vibrans ◽  
Jörg Bendix ◽  
Ramón Cuevas-Guzmán
Keyword(s):  
Invasive Species ◽  
Alien Species ◽  
Floristic Composition ◽  
Tree Cover ◽  
Herbaceous Plant ◽  
World Knowledge ◽  
Importance Value Index ◽  
Alien Plant ◽  
Western Mexico ◽  
Roadside Vegetation

Introduction: Numbers of alien plant species are rising around the globe, but not all of them become invasive. Whereas introductions have been documented for several decades in some regions of the world, knowledge on alien species in Western Mexico is limited. Here, we study roadside vegetation along an elevational gradient, which includes a protected area. Objective: We analysed the floristic composition of herbaceous alien species, their distribution patterns, and their relationship with various environmental factors. A relative importance value index (IVI) identified the most important and, therefore, probably invasive taxa. Methods: During 2017 and 2018, roadside vegetation was documented with 4-6 transects every 300 altitudinal meters, from 0 to 2 100 m, for a total of 37 transects. Each transect consisted of five 1 m² plots. All herbaceous species were registered and alien taxa identified. A cluster analysis distinguished grouping of species based on elevation. The potentially invasive species were identified by their IVI, based on the sum of relative frequency and density values. The influence of environmental variables was analysed with a canonical correspondence analysis. Results: Most alien species were grasses; other families were represented by one or two species. The species were grouped into three main clusters. The first group included rare species, the second consisted of species restricted to higher altitudes, and the third group were tropical taxa with a distribution from sea level to medium altitudes. The most important potentially invasive species were: Urochloa maxima, Melinis repens, Eragrostis ciliaris and Cynodon dactylon, all African grasses introduced for grazing. The IVI of the species was related to tree cover, leaf litter depth and surface stone cover for some species and, for others, to soil compaction, distance to major roads and elevation. Conclusions: The alien ruderal species clustered according to the general climate (temperate vs. tropical). Grasses of African origin are of highest concern as invasive species. Although most introductions are related to human disturbance, each species becomes dominant under certain environmental conditions. Thus, management programs must be specifically adjusted to each individual invasive alien.

AERIAL VIDEOGRAMMETRY FROM A TETHERED AIRSHIP TO ASSESS MANATEE LIFE-STAGE STRUCTURE

2000 ◽  
Vol 16 (3) ◽  
pp. 617-630 ◽  
Author(s):  
Richard O. Flamm ◽  
Edward C. G. Owen ◽  
Caryn F. W. Owen ◽  
Randall S. Wells ◽  
Doug Nowacek
Keyword(s):  
Life Stage ◽  
Stage Structure

scholarly journals Comparative effects of pollen and seed migration on the cytonuclear structure of plant populations. II. Paternal cytoplasmic inheritance.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 253-267
Author(s):  
A Schnabel ◽  
M A Asmussen
Keyword(s):  
Gene Flow ◽  
De Novo ◽  
Life Stage ◽  
Cytoplasmic Inheritance ◽  
Island Population ◽  
Mixed Mating ◽  
Plant Populations ◽  
Seed Migration ◽  
Self Fertilization ◽  
The Relationship

Abstract We continue our study of the effects of pollen and seed migration on the cytonuclear structure of mixed-mating plant populations by analyzing two deterministic continent-island models under the critical assumption of paternal cytoplasmic inheritance. The major results of this study that contrast with our previous conclusions based on maternal cytoplasmic inheritance are (i) pollen gene flow can significantly affect the cytonuclear structure of the island population, and in particular can help to generate cytonuclear disequilibria that greatly exceed the magnitude of those that would be produced by seed migration or mixed mating alone; (ii) with simultaneous pollen and seed migration, nonzero cytonuclear disequilibria will be maintained not only when there is disequilibrium in the immigrant pollen or seeds, but also through a variety of intermigrant admixture effects when the two pools of immigrants differ appropriately in their cytonuclear compositions; (iii) either immigrant pollen or immigrant seeds can generate disequilibria de novo in populations with initially random cytonuclear associations, but pollen migration alone generally produces lower levels of disequilibrium than does comparable seed migration, especially at high levels of self-fertilization when the overall fraction of immigrant pollen is low; (iv) the equilibrium state of the island population will be influenced by the rate of pollen gene flow whenever there is either allelic disequilibrium in the immigrant pollen or simultaneous seed migration coupled with different cytoplasmic or nuclear allele frequencies in immigrant pollen and seeds or nonzero allelic disequilibrium in either immigrant pool. The estimation of pollen migration should therefore be facilitated with paternal cytoplasmic inheritance relative to the case of maternal cytoplasmic inheritance. These basic conclusions hold whether the population is censused as seeds or as adults, but with simultaneous pollen and seed migration, the relationship between census time and the ability to detect nonrandom cytonuclear associations is complex. When migration is through pollen alone, however, the cytonuclear structure of the island population is independent of the life stage censused.

scholarly journals Comparative effects of pollen and seed migration on the cytonuclear structure of plant populations. I. Maternal cytoplasmic inheritance.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 639-654
Author(s):  
M A Asmussen ◽  
A Schnabel
Keyword(s):  
De Novo ◽  
Life Stage ◽  
Random Mating ◽  
Cytoplasmic Inheritance ◽  
Island Population ◽  
Mixed Mating ◽  
Seed Migration ◽  
Self Fertilization ◽  
Basic Behavior ◽  
Special Case

Abstract We explicitly solve and analyze a series of deterministic continent-island models to delimit the effects of pollen and seed migration on cytonuclear frequencies and disequilibria in random-mating, mixed-mating and self-fertilized populations. Given the critical assumption of maternal cytoplasmic inheritance, five major findings are (i) nonzero cytonuclear disequilibria will be maintained in the island population if and only if at least some migration occurs each generation through seeds with nonrandom cytonuclear associations; (ii) immigrant seeds with no cytonuclear disequilibria can strongly affect the genetic structure of the island population by generating significant and long-lasting transient associations; (iii) with all else being equal, substantially greater admixture disequilibria are generally found with higher rates of seed migration into, or higher levels of self-fertilization within, the island population (with the possible exception of the heterozygote disequilibrium); (iv) pollen migration can either enhance or reduce the cytonuclear disequilibria caused by seed migration, or that due to mixed-mating in the absence of seed migration, but the effect is usually small and appears primarily to make a noticeable difference in predominantly outcrossing populations; and (v) pollen migration alone cannot generate even transient disequilibria de novo in populations with completely random associations. This same basic behavior is exhibited as long as there is some random outcrossing in the island population. Self-fertilized populations represent a special case, however, in that they are necessarily closed to pollen migration, and nonzero disequilibria can be maintained even in the absence of seed migration. All of these general results hold whether the population is censused as adults or as seeds, but the ability to detect nonrandom cytonuclear associations can depend strongly on the life stage censused in populations with a significant level of random outcrossing. We suggest how these models might be used for the estimation of seed and pollen migration.

scholarly journals Stochastic Production Frontier Models to Explore Constraints on Household Travel Expenditures Considering Household Income Classes

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Sofyan M. Saleh ◽  
Sugiarto Sugiarto
Keyword(s):  
Household Income ◽  
Life Stage ◽  
Stage Structure ◽  
Professional Activity ◽  
Stochastic Production Frontier ◽  
Production Frontier ◽  
Household Travel Survey ◽  
Stochastic Production ◽  
Equity Policy ◽  
Household Travel

This paper explores the variation of household travel expenditure frontiers (HTEFs) prior to CC reform in Jakarta. This study incorporates the variation of household income classes into the modeling of HTEFs and investigates the degree to which various determinants influence levels of HTEF. The HTEF is defined as an unseen maximum (capacity) amount of money that a certain income class is willing to dedicate to their travel. A stochastic production frontier is applied to model and explore upper bound household travel expenditure (HTE). Using a comprehensive household travel survey (HTS) in Jakarta in 2004, the observed HTE spending in a month is treated as an exogenous variable. The estimation results obtained using three proposed models, for low, medium and high income classes, show that HTEFs are significantly associated with life stage structure attributes, socio-demographics and life environment factors such as professional activity engagements, which is disclosed to be varied across income classes. Finding further reveals that considerable differences in average of HTEFs across models. This finding calls for the formulation of policies that consider the needs to be addressed for low and medium income groups in order to promote more equity policy thereby leading to more acceptable CC reform.

scholarly journals Succession dynamics of vegetation in the Slovak Karst Biosphere Reserve Landscape (Western Carpathians)

2016 ◽  
Vol 35 (1) ◽  
pp. 13-31
Author(s):  
Ivan Vološčuk ◽  
Eva Uhliarová ◽  
Peter Sabo ◽  
Martina Škodová ◽  
Juaj Švajda
Keyword(s):  
Species Abundance ◽  
Biosphere Reserve ◽  
Permanent Plots ◽  
Grassland Vegetation ◽  
Dry Grassland ◽  
Brachypodium Pinnatum ◽  
Calamagrostis Epigejos ◽  
European Method ◽  
Field Plots ◽  
Trees And Shrubs

Abstract The paper presents results acquired by an ecological analysis of vegetation succession on the field of the Slovak Karst in south-east Slovakia over the past 25 years. The data were collected on permanent research plots etsablished in 1983−1985 on the Plešivská Plateau (part of the Slovak Karst National Park and Biosphere Reserve). Changes in mesic and dry grassland vegetation of permanent field plots were evaluated in the same way both times according to the Central European method. Due to cessation of non-forest vegetationmanagement the majority, permanent plots isgradually overgrownby woody plants. Succession of vegetation runs faster on karst plateaux where the trees and shrubs invasion is accompanied by overgrowing of grassland vegetation with Brachypodium pinnatum and Calamagrostis epigejos, which are completly change their species composition. On the steep limestone slopes and karst rocky fields of the lower altitudes the secondary succession is ongoing slower and is subjected mainly to accumulation of soil. Succession of herb layer is firstly reflected in changes of species abundance and later in exchanges of dominant species and plant communities. It was also evaluated succession in two forest habitats. In the community Fagetum typicum was evaluated succession after the artificial spruce wind calamity.

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