نتایج جستجو برای: evenness sheldon index

تعداد نتایج: 398318  

Journal: :IOP conference series 2021

Abstract This research aims to analyze the kelp, diversity, evenness, dominance, food characteristics, habitat and physical chemical parameters of Holothuroidea in Sancang marine preserve. The method used this is descriptive with sampling using purposive sampling, assisted by help lie transects, quadratic transect ecology Holothuroidea. Based on field observations, species exiting Cikabodasan b...

2016
Lin Liu Han Quan Bi-Cheng Dong Xiang-Qi Bu Lin Li Fu-De Liu Guang-Chun Lei Hong-Li Li

Nutrients may affect the invasiveness of alien plants and the invasibility of native plant communities. We performed a greenhouse experiment to investigate the interactive effect of invasion by a clonal herb Hydrocotyle vulgaris and nutrient enrichment on biomass and evenness of native plant communities. We established three types of plant communities (H. vulgaris alone, native plant communitie...

2012
J. Robin Svensson Mats Lindegarth Per R. Jonsson Henrik Pavia

The intermediate disturbance hypothesis (IDH) and the dynamic equilibrium model (DEM) are influential theories in ecology. The IDH predicts large species numbers at intermediate levels of disturbance and the DEM predicts that the effect of disturbance depends on the level of productivity. However, various indices of diversity are considered more commonly than the predicted number of species in ...

2007
Anto Anu Thomas K. Sabu

The diversity of litter ant assemblages in evergreen, deciduous and Shola evergreen (Shola) forest vegetation types of the Wayanad region of the Western Ghats was assessed employing conventional and taxonomic diversity indices. Non-dependence on quantitative data and the ability to relate the phylogenetic structure of assemblages with ecological conditions of the habitat, and to ascertain prior...

2015
Florentin Constancias Sébastien Terrat Nicolas P A Saby Walid Horrigue Jean Villerd Jean-Philippe Guillemin Luc Biju-Duval Virginie Nowak Samuel Dequiedt Lionel Ranjard Nicolas Chemidlin Prévost-Bouré

Despite the relevance of landscape, regarding the spatial patterning of microbial communities and the relative influence of environmental parameters versus human activities, few investigations have been conducted at this scale. Here, we used a systematic grid to characterize the distribution of soil microbial communities at 278 sites across a monitored agricultural landscape of 13 km². Molecula...

Journal: :Ecology letters 2009
Forest I Isbell H Wayne Polley Brian J Wilsey

Theory predicts that the temporal stability of productivity, measured as the ratio of the mean to the standard deviation of community biomass, increases with species richness and evenness. We used experimental species mixtures of grassland plants to test this hypothesis and identified the mechanisms involved. Additionally, we tested whether biodiversity, productivity and temporal stability were...

2017
Carlo Ricotta

The amount of variation in species composition among sampling units or beta diversity has become a primary tool for connecting the spatial structure of species assemblages to ecological processes. Many different measures of beta diversity have been developed. Among them, the total variance in the community composition matrix has been proposed as a single-number estimate of beta diversity. In th...

Knowledge of the relationships between biotic components of rangeland ecosystem i.e. herbivores and plants is important for range managers. In order to study herbivorse grazing intensity on plant species diversity, an experiment was conductef using fuor grazing treatments in darrehshar rangelands, Ilam province in 2015. Plant species data were taken based on a randomized-systematic sampling met...

Journal: :Journal of Pediatrics and Mother Care 2017

2013
Tapas kumar Dutta Bidhan C. Patra

Ponds are natural water sources that are used by man for various purposes. Zooplankton constitutes an important food item for fishes . Zooplankton also play an important role and serve as bioindicators as well as to assess the pollution status of water .In this present study, we tried to asses the zooplankton species richness, diversity and evenness and to state the condition of a freshwater tr...

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