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- Bezemer, T. M., et al.
(author)
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Divergent composition but similar function of soil food webs of individual plants: plant species and community effects
- 2010
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In: Ecology. - 0012-9658. ; 91:10, s. 3027-3036
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Journal article (peer-reviewed)abstract
- Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and providers of resources to the soil food web, are of vital importance for the composition, structure, and functioning of soil communities. However, whether natural soil food webs that are completely open to immigration and emigration differ underneath individual plants remains unknown. In a biodiversity restoration experiment we first compared the soil nematode communities of 228 individual plants belonging to eight herbaceous species. We included grass, leguminous, and non-leguminous species. Each individual plant grew intermingled with other species, but all plant species had a different nematode community. Moreover, nematode communities were more similar when plant individuals were growing in the same as compared to different plant communities, and these effects were most apparent for the groups of bacterivorous, carnivorous, and omnivorous nematodes. Subsequently, we analyzed the composition, structure, and functioning of the complete soil food webs of 58 individual plants, belonging to two of the plant species, Lotus corniculatus (Fabaceae) and Plantago lanceolata (Plantaginaceae). We isolated and identified more than 150 taxa/groups of soil organisms. The soil community composition and structure of the entire food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon mineralization or food web stability. Hence, the composition and structure of entire soil food webs vary at the scale of individual plants and are strongly influenced by the species identity of the plant. However, the ecosystem functions these food webs provide are determined by the identity of the entire plant community.
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- Leps, J, et al.
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Long-term effectiveness of sowing high and low diversity seed mixtures to enhance plant community development on ex-arable fields
- 2007
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In: Applied Vegetation Science. - 1402-2001. ; 10:1, s. 97-110
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Journal article (peer-reviewed)abstract
- Questions: How is succession on ex-arable land affected by sowing high and low diversity mixtures of grassland species as compared to natural succession? How long do effects persist? Location: Experimental plots installed in the Czech Republic, The Netherlands, Spain, Sweden and the United Kingdom. Methods: The experiment was established on ex-arable land, with five blocks, each containing three 10 m x 10 m experiment tal plots: natural colonization, a low- (four species) and high-diversity (15 species) seed mixture. Species composition and biomass was followed for eight years. Results: The sown plants considerably affected the whole successional pathway and the effects persisted during the whole eight year period. Whilst the proportion of sown species (characterized by their cover) increased during the study period, the number of sown species started to decrease from the third season onwards. Sowing caused suppression of natural colonizing species, and the sown plots had more biomass. These effects were on average larger in the high diversity mixtures. However, the low diversity replicate sown with the mixture that produced the largest biomass or largest suppression of natural colonizers fell within the range recorded at the five replicates of the high diversity plots. The natural colonization plots usually had the highest total species richness and lowest productivity at the end of the observation period. Conclusions: The effect of sowing demonstrated dispersal limitation as a factor controlling the rate of early secondary succession. Diversity was important primarily for its 'insurance effect': the high diversity mixtures were always able to compensate for the failure of some species.
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- Bukovinszky, Tibor, et al.
(author)
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Combined effects of patch size and plant nutritional quality on local densities of insect herbivores
- 2010
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In: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 11:5, s. 396-405
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Journal article (peer-reviewed)abstract
- Plant-insect interactions occur in spatially heterogeneous habitats. Understanding how such interactions shape density distributions of herbivores requires knowledge on how variation in plant traits (e.g. nutritional quality) affects herbivore abundance through, for example, affecting movement rates and aggregation behaviour. We studied the effects of plant patch size and herbivore-induced differences in plant nutritional quality on local densities of insect herbivores for two Brassica oleracea cultivars, i.e. white cabbage and Brussels sprouts. Early season herbivory as a treatment resulted in measurable differences in glucosinolate concentrations in both cultivars throughout the season. Herbivore induction and patch size both influenced community composition of herbivores in both cultivars, but the effects differed between species. Flea beetles (Phyllotreta spp.) were more abundant in large than in small patches, and this patch response was more pronounced on white cabbage than on Brussels sprouts. Herbivore-induction increased densities in all patches. Thrips tabaci was also more abundant in large patches and densities of this species were higher on Brussels sprouts than on white cabbage. Thrips densities were lower on induced than on control plants of both cultivars and this negative effect of induction tended to be more pronounced in large than in small patches. Densities of the cabbage moth (Mamestra brassicae) were lower on Brussels sprouts than on white cabbage and lower on herbivore-induced than on uninduced plants, with no effect of patch size. No clear effects of patch size and induction were found for aphids. This study shows that constitutive and herbivore-induced differences in plant traits interact with patch responses of insect herbivores.
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- Clerbaux, LA, et al.
(author)
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Factors Modulating COVID-19: A Mechanistic Understanding Based on the Adverse Outcome Pathway Framework
- 2022
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In: Journal of clinical medicine. - : MDPI AG. - 2077-0383. ; 11:15
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Journal article (peer-reviewed)abstract
- Addressing factors modulating COVID-19 is crucial since abundant clinical evidence shows that outcomes are markedly heterogeneous between patients. This requires identifying the factors and understanding how they mechanistically influence COVID-19. Here, we describe how eleven selected factors (age, sex, genetic factors, lipid disorders, heart failure, gut dysbiosis, diet, vitamin D deficiency, air pollution and exposure to chemicals) influence COVID-19 by applying the Adverse Outcome Pathway (AOP), which is well-established in regulatory toxicology. This framework aims to model the sequence of events leading to an adverse health outcome. Several linear AOPs depicting pathways from the binding of the virus to ACE2 up to clinical outcomes observed in COVID-19 have been developed and integrated into a network offering a unique overview of the mechanisms underlying the disease. As SARS-CoV-2 infectibility and ACE2 activity are the major starting points and inflammatory response is central in the development of COVID-19, we evaluated how those eleven intrinsic and extrinsic factors modulate those processes impacting clinical outcomes. Applying this AOP-aligned approach enables the identification of current knowledge gaps orientating for further research and allows to propose biomarkers to identify of high-risk patients. This approach also facilitates expertise synergy from different disciplines to address public health issues.
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- Rasmussen, Pil Uthaug, 1987-
(author)
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Plant-associated soil communities : Patterns, drivers and aboveground consequences
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Soil contains a wealth of diversity – bacteria, fungi, nematodes, arthropods and earthworms are just some of the many organisms found belowground. These organisms play an important role in shaping the soil environment and they strongly influence plant fitness, diversity and community composition. Their impact even cascades up to affect aboveground species interactions. Ultimately, belowground organisms are a vital part of ecosystem functioning. Nevertheless, most of the diversity and ecology of belowground organisms are to this day unknown, and increasing our insights into the role and ecology of soil organisms is of importance for natural and agricultural systems.The main goal of this thesis was to investigate spatial patterns of plant-associated soil communities (I, II), to identify the drivers of such spatial patterns (I, II, III), and to study some of the consequences of belowground spatial patterns for aboveground species interactions (IV). To answer these questions, I used both observational studies and multifactorial experiments in combination with microscopy and metabarcoding. I focused on the plant Plantago lanceolata (ribwort plantain) and its root-associated soil microbes, with a strong emphasis on arbuscular mycorrhizal fungi, an important group of root symbionts.I found that in natural environments arbuscular mycorrhizal fungal communities frequently show high small-scale variation (I). In the following work I showed that the pattern of high small-scale heterogeneity may be due to dispersal limitation (II), abiotic conditions such as pH, soil nutrients and climate (I, III), and biotic conditions, such as interspecific community composition and genetic variation (I, II). The high variation at small spatial scales (I) in combination with genetic variation of plants and insects (IV) may help maintain high local heterogeneity in aboveground plant-associated communities, thereby influencing aboveground diversity and dynamics.The insight gained here has increased our general knowledge on the distribution of soil microbes and the interactions taking place above and belowground. It has furthermore laid a foundation for future work on the world of soil microbes and their implications aboveground.
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