| 1. |
- Abiven, Samuel, et al.
(författare)
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Biochar amendment increases maize root surface areas and branching : a shovelomics study in Zambia
- 2015
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 395:1-2, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- Positive crop yield effects from biochar are likely explained by chemical, physical and/or biological factors. However, studies describing plant allometric changes are scarcer, but may be crucial to understand the biochar effect. The main aim of the present study is to investigate the effect of biochar on root architecture under field conditions in a tropical setting. The presented work describes a shovelomics (i.e., description of root traits in the field) study on the effect of biochar on maize root architecture. Four field experiments we carried out at two different locations in Zambia, exhibiting non-fertile to relatively fertile soils. Roots of maize crop (Zea mays L.) were sampled from treatments with fertilizer (control) and with a combination of fertilizer and 4 t.ha(-1) maize biochar application incorporated in the soil. For the four sites, the average grain yield increase upon biochar addition was 45 +/- 14 % relative to the fertilized control (from 2.1-6.0 to 3.1-9.1 ton ha(-1)). The root biomass was approximately twice as large for biochar-amended plots. More extensive root systems (especially characterized by a larger root opening angle (+14 +/- 11 %) and wider root systems (+20 +/- 15 %)) were observed at all biochar-amended sites. Root systems exhibited significantly higher specific surface areas (+54 +/- 14 %), branching and fine roots: +70 +/- 56 %) in the presence of biochar. Biochar amendment resulted in more developed root systems and larger yields. The more extensive root systems may have contributed to the observed yield increases, e.g., by improving immobile nutrients uptake in soils that are unfertile or in areas with prolonged dry spells.
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| 2. |
- Affholder, Marie-Cecile, et al.
(författare)
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Can Cd content in crops be controlled by Se fertilization? A meta-analysis and outline of Cd sequestration mechanisms
- 2019
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 440, s. 369-380
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Tidskriftsartikel (refereegranskat)abstract
- Aim Cadmium mitigation in crops is a worldwide concern. Selenium application has been suggested as a potential solution to reduce cadmium concentration in plants, but published results were contradictory. We analysed literature data with respect to the effect of selenium addition on cadmium uptake and elucidated processes possibly involved.Method A meta-analysis was performed on data collected from previously published studies presenting cadmium concentration in plants subjected to selenium treatments. Metaregression random models were run to test the impact of different factors. In addition, soil and crop inventory data exemplifying the natural variation of Cd and Se in soil were evaluated.Results The results highlighted a significant reduction of cadmium concentration in crops after selenium addition. The reduction was dose-dependent for crops growing under aerobic, but not for plants cultivated under anoxic conditions such as rice. This suggests that different process can be involved.Conclusion We demonstrated the potential of selenium fertilization to mitigate cadmium uptake and highlighted that for non-rice species, the main process seems to take place in the soil, while mechanisms in roots restricting uptake may be involved for all crops. The inventory data also indicated an impact of natural soil Se on Cd contents in crops.
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| 3. |
- Agback, Peter, et al.
(författare)
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Root morphology and cluster root formation by seabuckthorn (Hippophae rhamnoides L.) in response to nitrogen, phosphorus and iron deficiency
- 2015
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 397, s. 75-91
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Tidskriftsartikel (refereegranskat)abstract
- The aims were to investigate effects of availability of nitrogen (N), phosphorus (P) and iron (Fe) on root properties of seabuckthorn (HippophaA << rhamnoides) and to test the hypothesis that seabuckthorn is able to form cluster roots (CRs).Two sources of seabuckthorn were used: the seabuckthorn cultivar BHi10726 originating from a breeding programme based on H.r. ssp mongolica and carried out in rich agricultural field soil in the black earth (chernozem) region of Russia and the seabuckthorn accession named Pk originating in a natural population of H.r. ssp turkestanica in the mountainous region of northern Pakistan. Three cultivation systems giving different water availabilities were used at two levels each of N, P and Fe. Root morphology of seedlings and clones was characterized and metabolite content in extracts of young and old CRs of Pk was analyzed by proton nuclear magnetic resonance spectroscopy.Availability of N affected growth and distribution of biomass between shoot and root, while P and Fe deficiency modified root system architecture towards more lateral roots. Densely positioned rootlets with a determinate type of growth consistent with the definition of CR were observed under low P and low Fe. Pk formed on average 12 CRs per plant, which was 3 to 4-fold higher compared to BHi10726 also when normalized per root length. Malate and glycine were most abundant of the organic acids and amino acids, respectively, and decreased in old CRs.Seabuckthorn has the ability to form cluster roots especially in Pk and under deficiency of P and Fe. The two sources of seabuckthorn with different histories showed distinctly different root system architectures. The high contents of malate and glycine and their decrease in old CRs may reflect roles in CR metabolism.
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| 4. |
- Bahr, Adam, et al.
(författare)
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Nitrogen leaching and ectomycorrhizal nitrogen retention capacity in a Norway spruce forest fertilized with nitrogen and phosphorus
- 2015
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 390:1-2, s. 323-335
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Tidskriftsartikel (refereegranskat)abstract
- To estimate the production of external ectomycorrhizal mycelia (EMM) in Norway spruce forests with varying nitrogen (N) and phosphorus (P) levels, and to relate this to the N retention capacity of ectomycorrhizal fungi (EMF) and N leaching. Seasonal changes in EMF production (in ingrowth mesh bags) and soil water N (in suction lysimeters) were analyzed after fertilization with N or N combined with P. The EMF N retention capacity was estimated by the addition of isotopically labeled N to the mesh bags. No relationship was found between the seasonal variation in EMF growth and N leakage from the soil. However, in the mesh bags, the total assimilation of N-15 by EMF was almost halved by N fertilization, while twice as much N-15 leached through. We found a high specific N assimilation capacity per unit weight of EMF mycelia. This was unaffected by N fertilization, but the total assimilation of N by EMF was drastically reduced due to reduced production of EMM. However, N-retaining processes other than N assimilation by EMF must be taken into account to explain the losses of N after fertilization.
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| 5. |
- Bahram, Mohammad
(författare)
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The role of arbuscular mycorrhizal fungi in plant invasion trajectory
- 2019
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 441, s. 1-14
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Forskningsöversikt (refereegranskat)abstract
- Background Invasive plant species pose a global threat because they alter ecosystem functioning and biodiversity. The majority of plants form mutualistic mycorrhizal associations with mycorrhizal fungi, which contribute to the nutrient and water supply as well as diversity, competitive ability, and ecosystem productivity. In addition, the role of mycorrhizal interactions in plant invasiveness and the susceptibility or resistance of a habitat to invasion is increasingly recognized. However, the mechanisms by which mycorrhizae contribute to invasion remain unresolved. Scope Here, we provide an overview of the empirical evidence and discuss the prospects for mycorrhizaemediated plant invasion. Overall, mycorrhizal fungi appear to have impacts on plant invasion that depend on the similarities between the mycorrhizal associations of the alien and native plants. We introduce plant mycorrhizal niche space (PMNS) as a plant's ability to exploit and shape the mycorrhizal fungi pool of a habitat based on its dependency on mycorrhizal fungi, traits and priority effects. Conclusions Collectively, the available evidence supports the idea that PMNS is independent of place of origin (invasive status). Understanding the drivers of the PMNS of both native and alien plant species may help to predict the potential invasiveness of plants and the invasibility of a habitat, to elucidate the role of the mycorrhizal fungal community in plant invasion and the impact of plant invasion on the structure of the mycorrhizal fungal community in new habitats (i.e., neighbour effect) and to improve restoration planning. In this regard, we highlight a number of knowledge gaps and discuss future research directions.
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| 6. |
- Bandau, Franziska, et al.
(författare)
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Genotypic variability in Populus tremula L. affects how anthropogenic nitrogen enrichment influences litter decomposition
- 2017
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 410:1-2, s. 467-481
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Tidskriftsartikel (refereegranskat)abstract
- Boreal forests can receive substantial nitrogen (N) enrichment via atmospheric N deposition and industrial forest fertilization. While it is known that N enrichment can impact ecosystem properties, such as litter decomposition, it remains poorly understood how genetic variability within plant species modifies these impacts. We grew replicates of ten Populus tremula L. genotypes (GTs) under 3 N conditions; ambient, and levels representing atmospheric N deposition and industrial forest fertilization. We measured leaf and litter physical and chemical traits, and conducted a litter decomposition assay. Leaf traits varied due to N treatment, GT, and constitutive tannin levels. Leaf traits were in some cases correlated with litter traits, and decomposition was influenced by single and interactive effects of N and GT. Nitrogen addition unexpectedly decelerated decomposition, potentially due to changes in specific leaf area (SLA). Variation in decomposition rates among the GTs was best explained by their differences in SLA, and lignin:N ratio. Nitrogen addition also caused a shift in which traits most strongly influenced decomposition. Our findings highlight that the considerable diversity present in tree species can have a strong influence on ecosystem processes, such as decomposition, and how these processes respond to environmental change.
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| 7. |
- Bengtsson, Fia, et al.
(författare)
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Biochemical determinants of litter quality in 15 species of Sphagnum
- 2018
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 425:1-2, s. 161-176
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims Sphagnum mosses are ecosystem engineers that create and maintain boreal peatlands. With unique biochemistry, waterlogging and acidifying capacities, they build up meters-thick layers of peat, reducing competition and impeding decomposition. We quantify within-genus differences in biochemical composition to make inferences about decay rates, related to hummock-hollow and fen-bog gradients and to phylogeny. Methods We sampled litter from 15 Sphagnum species, abundant over the whole northern hemisphere. We used regression and Principal Components Analysis (PCA) to evaluate general relationships between litter quality parameters and decay rates measured under laboratory and field conditions. Results Both concentrations of the polysaccharide sphagnan and the soluble phenolics were positively correlated with intrinsic decay resistance, however, so were the previously understudied lignin-like phenolics. More resistant litter had more of all the important metabolites; consequently, PC1 scores were related to lab mass loss (R-2 = 0.57). There was no such relationship with field mass loss, which is also affected by the environment. PCA also revealed that metabolites clearly group Sphagnum sections (subgenera). Conclusions We suggest that the commonly stated growth-decomposition trade-off is largely due to litter quality. We show a strong phylogenetic control on Sphagnum metabolites, but their effects on decay are affected by nutrient availability in the habitat.
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| 8. |
- Bohlin, Elisabet, et al.
(författare)
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Phylogenetic or environmental control on the elemental and organo-chemical composition of Sphagnum mosses?
- 2017
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 417, s. 69-85
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Tidskriftsartikel (refereegranskat)abstract
- Plant litter chemistry is a key driver of decomposition in peatlands. This study explored the relative contributions of phylogeny and environment to litter chemistry of peat mosses (Sphagnum), the key peat-forming plants on earth.Fifteen Sphagnum species, representing three taxonomic sections ACUTIFOLIA, CUSPIDATA and SPHAGNUM, were sampled across a wide range of hydro-geochemical conditions. For all species we characterised chemical composition within (i) inorganic elements, (ii) carbohydrate polymers (iii) non-carbohydrates.The variation in carbohydrates was mostly explained by taxonomic section, suggesting phylogenetic conservation of carbohydrate composition. ACUTIFOLIA species invested relatively more in pectins, whereas CUSPIDATA and SPHAGNUM species invested more in hemicellulose. The composition of non-carbohydrates was mainly influenced by environment, except for some constituents for which the variation was more correlated to phylogeny. Finally, the variation in inorganic element concentrations mostly reflected hydro-geochemical conditions within and between peatlands.The separation into an environmentally independent, phylogenetically conserved group of compounds (structural carbohydrates) and an environmentally dependent, variable group of compounds (inorganic elements, non-carbohydrates) has important implications both for understanding patterns in and for upscaling of spatially variable ecosystem processes associated with peat decomposition such as carbon sequestration, nutrient cycling and greenhouse gas emissions.
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| 9. |
- Caruso, Tancredi, et al.
(författare)
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Assessing soil ecosystem processes – biodiversity relationships in a nature reserve in Central Europe
- 2018
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 424:1-2, s. 491-501
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Plant diversity – ecosystem processes relationships are essential to our understanding of ecosystem functioning. We aimed at disentangling the nature of such relationships in a mesotrophic grassland that was highly heterogeneous with regards to nutrient availability. Methods: Rather than targeting primary productivity, like most existing reports do, we focused our study on belowground ecosystem processes. We tested three, largely mutually exclusive, hypotheses of ecosystem processes relationships: the redundancy hypothesis, the insurance hypothesis and the centrifugal model hypothesis. We sampled the grassland twice within a single plant growing season in a spatially explicit way and assayed the soil for nitrification, urease activity, relative bacterial activity and a microbial community profile based on respiration while we simultaneously assessed plant diversity. Results: Results supported the centrifugal model. We justify the lack of support for the other two hypotheses on the basis of having conducted an observational study in an environmentally heterogeneous site. Conclusions: The centrifugal model hypothesis appears to be a very good predictive model for explaining diversity in observational, heterogeneous studies. The specific study represents one of the few observational studies that consider measures of ecosystem functioning other than primary productivity.
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| 10. |
- Colesie, Claudia
(författare)
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Ecophysiological properties of three biological soil crust types and their photoautotrophs from the Succulent Karoo, South Africa
- 2018
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 429, s. 127-146
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Biological soil crusts cover about one third of the terrestrial soil surfaces in drylands, fulfilling highly important ecosystem services. Their relevance to global carbon cycling, however, is still under debate.Methods We utilized CO2 gas exchange measurements to investigate the net photosynthetic response of combined cyanobacteria/cyanolichen-, chlorolichen- and moss-dominated biocrusts and their isolated photoautotrophic components to light, temperature, and water. The results were compared with field studies to evaluate their compatibility.Results Different biocrust types responded similarly, being inhibited by limited and excess water, saturated by increasing light intensities, and having optimum temperatures. Cyanobacteria/cyanolichen-dominated biocrusts reached their water optimum at lowest contents (0.52-0.78 mm H2O), were saturated at highest light intensities, and had a comparably high temperature optimum at 37 degrees C. Chlorolichen-dominated crusts had a medium water optimum (0.75-1.15 mm H2O), medium saturating light intensities and a moderate temperature optimum of 22 degrees C. Moss-dominated biocrusts had the highest water optimum (1.76-2.38 mm H2O), lowest saturating light intensities, and a similar temperature optimum at 22 degrees C. Isolated photoautotrophs responded similar to complete crusts, only isolated moss stems revealed much lower respiration rates compared to complete crusts.Conclusions In addition to their overall functional similarities, cyanobacteria/cyanolichen-dominated biocrusts appeared to be best adapted to predicted climate change of increasing temperatures and smaller precipitation events, followed by chlorolichen-dominated biocrusts. Moss-dominated biocrusts needed by far the largest amounts of water, thus likely being prone to anticipated climate change.
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