scholarly journals Effects of Mowing Frequency on Soil Nematode Diversity and Community Structure in a Chinese Meadow Steppe

2021 ◽  
Vol 13 (10) ◽  
pp. 5555
Author(s):  
Jinling Zhao ◽  
Jiale Chen ◽  
Honghui Wu ◽  
Linghao Li ◽  
Fengjuan Pan
Keyword(s):  
Community Structure ◽  
Critical Factor ◽  
Terrestrial Ecosystems ◽  
Structure Stability ◽  
Soil Nematode ◽  
Soil Nematodes ◽  
Grassland Ecosystems ◽  
Management Measures ◽  
Nematode Diversity ◽  
The Stability

Soil nematodes are one of the most important components in terrestrial ecosystems and the critical factor driving the belowground process. The grasslands of Northeast China have been subject to mowing for ages, which theoretically should have had substantial effects on the processes associated with soil nematodes. However, relevant studies have barely been conducted to date. This study examined variations in soil nematode abundance, biomass, diversity, and community structure, with respect to varying mowing frequencies. The results showed that a higher mowing frequency significantly reduced the abundance of soil nematodes, biomass, diversity, and community structure stability in the ecosystem, while intermediate mowing frequency enhanced these parameters to different extents. Our findings indicate that the changing patterns of the nematode indices with mowing frequency conform to the intermediate disturbance theory. This study provides a theoretical basis for formulating grassland-related management measures and maintaining the stability of grassland ecosystems.

scholarly journals Effects of Grazing Intensity on Soil Nematode Community Structure and Function in Different Soil Layers in a Meadow Steppe

2021 ◽  
Author(s):  
Fengjuan Pan ◽  
Ruirui Yan ◽  
Jinling Zhao ◽  
Linghao Li ◽  
Yanfeng Hu ◽  
...  
Keyword(s):  
Community Structure ◽  
Soil Layer ◽  
Nematode Community ◽  
Soil Nematode ◽  
Soil Nematodes ◽  
Meadow Steppe ◽  
Soil Layers ◽  
Soil Nematode Community ◽  
Nematode Diversity ◽  
Grazing Intensities

Abstract Aims Grazing is a key driver of plant communities and soil functions in grassland ecosystems. Soil nematodes play a vital role in soil ecological functions. however, few studies have explored how grazing shapes soil nematode community in different soil layers.Methods we investigated the composition, abundance, diversity, metabolic footprint, and food web metrics of soil nematodes over a gradient of grazing in the 0-10 cm and 10-20 cm soil layers in a meadow steppe. The relationships between nematode community structure and biotic and abiotic factors were analyzed by principal component analysis (PCA) and structural equation model (SEM) analysis. Results Light grazing tended to increase the abundance of soil nematodes. Intensive grazing decreased the biomass carbon and metabolic footprints of plant parasites, fungivores, and total soil nematodes in 0-10 cm soils. There was no difference in the biomass carbon and metabolic footprints of soil nematodes among different grazing intensities in the 10-20 cm soil layer. Soil moisture, aboveground biomass, belowground biomass and Shannon diversity of grass contributed more to changes in soil nematode composition in both soil layers. In the 0-10 cm soil layer, grazing directly and indirectly affected soil nematode diversity via soil moisture and aboveground biomass, while grazing directly affected soil nematode diversity in 10-20 cm soil layer. Conclusions Our results indicate that soil depth can weaken the effect of grazing intensities on soil nematode fauna. Grazing affected the soil nematode community structure via different paths in different soil layers.

scholarly journals Distribution of nematodes in wetland soils with difference distance from the Bohai sea 359–366

2008 ◽  
Vol 54 (No. 8) ◽  
pp. 359-366 ◽  
Author(s):  
H.Y. Wu ◽  
X.X. Li ◽  
L.B. Shi ◽  
Z.H. Wang ◽  
F.Y. Ma
Keyword(s):  
Community Structure ◽  
Bohai Sea ◽  
Coastal Wetland ◽  
Yellow River ◽  
Nematode Community ◽  
Soil Nematode ◽  
Soil Nematodes ◽  
Nematode Communities ◽  
Plant Parasitism ◽  
Soil Nematode Communities

In order to elucidate the distribution of soil nematodes in coastal wetlands and the effect of different distance from the sea line on soil nematode communities, we investigated the community structure of soil nematodes in one wetland perpendicularly oriented from Bohai sea coastline. In June 2006, soil samples were collected from the Yellow River Delta wetlands, in Dongying city of Shandong Province, China. Soil nematode communities were analyzed at the depths of 0–10 and 10–20 cm. The results showed that plant parasite nematodes were the most abundant trophic groups in both depths and at four sites. The average relative abundance was 91.33% of the nematode community. Several ecological indices which reflected soil nematode community structure, diversity, maturity and plant parasitism were compared in these four sites. The results indicated that the maturity index (MI) and plant parasitism index (PPI) were more sensitive than the other indices for assessing the response of soil nematode communities to soil of coastal wetland.

scholarly journals Effect of transgenic insect-resistant maize to the community structure of soil nematodes in two field trials

2015 ◽  
Vol 52 (1) ◽  
pp. 41-49
Author(s):  
A. Čerevková ◽  
L Cagáň
Keyword(s):  
Community Structure ◽  
Food Web ◽  
Field Trials ◽  
Soil Nematode ◽  
Soil Nematodes ◽  
Soil Food Web ◽  
Bt Maize ◽  
Maize Hybrid ◽  
Nematode Communities ◽  
Soil Nematode Communities

Summary The aim of this study was to determine the effects of Bt maize hybrid cultivation on soil nematode communities in two field trials, as well as to analyse other factors (fertilisation and moisture) responsible for the community structure of soil nematodes. Nematode communities were studied in maize plots at the locality of Borovce in western Slovakia. During 2012 and 2013, hybrids DK440 and DKC3871 (conventional) or DKC4442YG and DKC3872YG (Bt maize, event MON810) were sown in 10 repetitions each. Nematodes were extracted from soil samples collected at the maize flowering (July 11, 2012 and July 30, 2013). Altogether, 39 nematode species belonged to 35 genera were identified in two maize variants. The dominant taxa in both variants were Acrobeloides nanus, Ce-phalobus persegnis, Aphelenchoides composticola, Aphelenchus avenae, Eudorylaimus carteri and Filenchus vulgaris. Calculation of the maturity index, plant parasitic index, enrichment index and structure index did not confirm any clear influence of year or hybrid type on soil nematode communities. The proportional representation of cp-1, cp-2 and cp-3-5 groups of nematode fauna indicated conditions of low stability and high stress. Faunal profiles representing the structure and enrichment conditions of the soil food web showed an environment with a high C:N ratio and high levels of fungal feeders. Based on the calculation of the metabolic footprint of nematodes in the soil food web, a difference between the isoline maize variant and Bt maize variant in 2012 was found, but this difference was not readily apparent in 2013. The occurrence of nematodes, their abundance, proportion of feeding types and selected ecological indices did not depend on the type of maize hybrid (Bt or non-Bt). Thus, the cultivation of genetically modified maize did not directly influence nematode populations. The application of fertiliser at certain periods does not influence the nematode community. The observed significant higher abundance of nematodes was correlated with soil moisture.

Higher taxa vs. functional guilds vs. trophic groups as indicators of soil nematode diversity and community structure

2014 ◽  
Vol 41 ◽  
pp. 25-29 ◽  
Author(s):  
Daya Ram Bhusal ◽  
Athanasios S. Kallimanis ◽  
Maria A. Tsiafouli ◽  
Stefanos P. Sgardelis
Keyword(s):  
Community Structure ◽  
Soil Nematode ◽  
Trophic Groups ◽  
Functional Guilds ◽  
Higher Taxa ◽  
Nematode Diversity

scholarly journals Nematode diversity, abundance and community structure 50 years after the formation of the volcanic island of Surtsey

2014 ◽  
Vol 11 (10) ◽  
pp. 14239-14267
Author(s):  
K. Ilieva-Makulec ◽  
B. Bjarnadottir ◽  
B. D. Sigurdsson
Keyword(s):  
Community Structure ◽  
Soil Depth ◽  
Plant Cover ◽  
Soil Nematode ◽  
Volcanic Island ◽  
Nutrient Inputs ◽  
Soil C ◽  
Nematode Communities ◽  
Nematode Diversity ◽  
Nematode Abundance

Abstract. The soil nematode fauna can give important insights into soil development and other habitat changes that occur during primary succession. We investigated the generic composition, density, distribution and community structure of nematodes 50 years after the formation of a pristine volcanic island, Surtsey, Iceland. Part of the island has received additional nutrient inputs from seagulls breeding there since 1985, while the reminder has been much less affected and is at present found at a different successional sere. In total, 25 genera of nematodes were identified, of which 14 were reported on Surtsey for the first time. Nematode communities were more diverse in the more infertile area outside the gull colony, where 24 genera were found, compared to 18 inside. The trophic structure of the nematode communities showed relatively higher abundance of fungal feeders in the infertile areas, but relatively more bacterial- and plant-feeders inside the colony. Nematode abundance in surface soil was, however, significantly higher within the gull colony, with 16.7 ind. cm−2 compared to 3.6 ind. cm−2 outside. A multivariate analysis indicated that the nematode abundance and distribution on Surtsey were most strongly related to the soil C : N ratio, soil acidity, plant cover and biomass, soil temperature and soil depth.

scholarly journals Functional Diversity of Soil Nematodes in Relation to the Impact of Agriculture—A Review

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 64
Author(s):  
Stela Lazarova ◽  
Danny Coyne ◽  
Mayra G. G. Rodríguez ◽  
Belkis Peteira ◽  
Aurelio Ciancio
Keyword(s):  
Functional Diversity ◽  
Disease Transmission ◽  
Ecosystem Functioning ◽  
Management Practices ◽  
Experimental Studies ◽  
Detailed Knowledge ◽  
Soil Nematode ◽  
Soil Nematodes ◽  
Nematode Diversity ◽  
The Impact

The analysis of the functional diversity of soil nematodes requires detailed knowledge on theoretical aspects of the biodiversity–ecosystem functioning relationship in natural and managed terrestrial ecosystems. Basic approaches applied are reviewed, focusing on the impact and value of soil nematode diversity in crop production and on the most consistent external drivers affecting their stability. The role of nematode trophic guilds in two intensively cultivated crops are examined in more detail, as representative of agriculture from tropical/subtropical (banana) and temperate (apple) climates. The multiple facets of nematode network analysis, for management of multitrophic interactions and restoration purposes, represent complex tasks that require the integration of different interdisciplinary expertise. Understanding the evolutionary basis of nematode diversity at the field level, and its response to current changes, will help to explain the observed community shifts. Integrating approaches based on evolutionary biology, population genetics and ecology can quantify the contribution of nematode fauna to fundamental soil functions. These include carbon transformation, nutrient cycling, pest control and disease transmission. In conclusion, different facets of nematode diversity such as trophic groups, life history traits, variability in body size and/or taxa identities in combination with DNA-based techniques are needed in order to disclose nematode–soil–ecosystem functioning relationships. Further experimental studies are required to define locally adapted and sustainable management practices, through ecosystem-based approaches and nature-based solutions.

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

scholarly journals Pygidial Glands in Carabidae, an Overview of Morphology and Chemical Secretion

Life ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 562
Author(s):  
Anita Giglio ◽  
Maria Luigia Vommaro ◽  
Pietro Brandmayr ◽  
Federica Talarico
Keyword(s):  
Community Structure ◽  
Carboxylic Acids ◽  
Biological Function ◽  
Terrestrial Ecosystems ◽  
Carabid Beetles ◽  
Diverse Families ◽  
Pygidial Glands ◽  
Predator Community ◽  
Behavioural Adaptations ◽  
Chemical Secretion

Predator community structure is an important selective element shaping the evolution of prey defence traits and strategies. Carabid beetles are one of the most diverse families of Coleoptera, and their success in terrestrial ecosystems is related to considerable morphological, physiological, and behavioural adaptations that provide protection against predators. Their most common form of defence is the chemical secretion from paired abdominal pygidial glands that produce a heterogeneous set of carboxylic acids, quinones, hydrocarbons, phenols, aldehydes, and esters. This review attempts to update and summarise what is known about the pygidial glands, with particular reference to the morphology of the glands and the biological function of the secretions.

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