| 1. |
- Bahr, Adam, et al.
(författare)
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Long-term changes in vegetation and soil chemistry in a calcareous and sandy semi-natural grassland
- 2012
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Ingår i: Flora: Morphology, Distribution, Functional Ecology of Plants. - : Elsevier BV. - 0367-2530. ; 207:5, s. 379-387
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Tidskriftsartikel (refereegranskat)abstract
- Calcicole plant species are vulnerable to acidification and fertilization, caused by deposition and changes in land use, since they are adapted to nutrient-poor calcareous conditions. In this study we used vegetation data (vascular plants, bryophytes and lichens) from 1964 and 1985 and stored soil samples from 1966 to investigate long-term soil chemistry and vegetation changes in a semi-natural, sandy calcareous grassland in southern Sweden. In the re-investigation in 2008 we found that increased decalcification due to acidification could not be verified. The plant community had changed from stress-tolerant calcareous grassland towards a community promoted by higher nutrient availability. Furthermore, the cover of species indicating calcareous conditions had decreased. A decline in the cover of species adapted to alkaline, phosphorus-poor conditions may be due to increased nutrient availability, but there were also indications that the vegetation had changed due to overgrowth by woody plants. This long-term impoverishment of the plant community highlights the need for appropriate management of calcareous grasslands, in order to limit the nutrients available in the soil and prevent overgrowth by shrubs and trees. (C) 2012 Published by Elsevier GmbH.
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| 2. |
- Lekberg, Ylva, et al.
(författare)
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454-sequencing reveals stochastic local reassembly and high disturbance tolerance within arbuscular mycorrhizal fungal communities
- 2012
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Ingår i: Journal of Ecology. - : Wiley. - 1365-2745 .- 0022-0477. ; 100:1, s. 151-160
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Tidskriftsartikel (refereegranskat)abstract
- 1. Disturbance is assumed to be a major driver of plant community composition, but whether similar processes operate on associated soil microbial communities is less known. Based on the assumed trade-off between disturbance tolerance and competiveness, we hypothesize that a severe disturbance applied within a semi-natural grassland would shift the arbuscular mycorrhizal (AM) fungal community towards disturbance-tolerant fungi that are rare in undisturbed soils.
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| 3. |
- Mårtensson, Linda-Maria, et al.
(författare)
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Allocation of carbon to mycorrhiza in the grasses Koeleria glauca and Corynephorus canescens in sandy grasslands
- 2012
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 54, s. 55-62
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Tidskriftsartikel (refereegranskat)abstract
- By investigating both semi-natural and experimentally implemented pH variation in nutrient-poor sandy grasslands, we examined how soil decalcification may influence the arbuscular mycorrhizal (AM) fungal biomass in plant roots and in the soil, as well as the allocation of carbon (C) to AM fungal biomass. We estimated the amount of AM fungal mycelium, by using the fatty acid 16:1 omega 5, in the roots and in the soil surrounding the roots of two grass species in a pH gradient, and in one grass in an experimental area. We investigated the allocation of C to the AM fungi by using in situ C-13 labelling. Contrary to our expectations, we found a decrease in AM fungal mycelium in the soil with increasing soil pH, and no significant relationship between soil pH and the amount of AM fungi in the roots. We also found that the allocation of C below ground was very small in the grasses investigated: the excess of C-13 in the roots after five days was only between 0.06 and 1.2% of the excess of C-13 in the shoots directly after labelling. The allocation of C to the extraradical AM mycelium also decreased with increasing pH, ranging from not detectable to 1.2 mu g C-13 g(-1) dry soil in the range of soil pH from 5.5 to 8.5. Experimental manipulation of decalcification through soil perturbation further supported the finding that AM fungal density is higher in decalcified areas, although it was not statistically significant in this case. We conclude that the amount of AM fungi is very low in this type of nutrient and drought stressed habitat, and that a high pH in the topsoil does not leads to higher AM fungal biomass. (C) 2012 Elsevier B.V. All rights reserved.
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| 4. |
- Nielsen, Knud Brian, et al.
(författare)
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Colonization of new land by arbuscular mycorrhizal fungi
- 2016
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048. ; 20, s. 22-29
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Tidskriftsartikel (refereegranskat)abstract
- The study describes the primary assembly of arbuscular mycorrhizal communities on a newly constructed island Peberholm between Denmark and Sweden. The AM fungal community on Peberholm was compared with the neighboring natural island Saltholm. The structure of arbuscular mycorrhizal communities was assessed through 454 pyrosequencing. Internal community structure was investigated through fitting the rank-abundance of Operational Taxonomic Units to different models. Heterogeneity of communities within islands was assessed by analysis of group dispersion. The mean OTU richness per sample was significantly lower on the artificial island than on the neighboring natural island, indicating that richness of the colonizing AM fungal community is restricted by limited dispersal. The AM fungal communities colonizing the new island appeared to be a non-random subset of communities on the natural and much older neighboring island, which points to high colonization potential of certain - probably early successional - mycorrhizal fungi, likely assisted by migratory birds.
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| 5. |
- Olsson, Pål Axel, et al.
(författare)
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pH preferences of red-listed gasteromycetes in calcareous sandy grasslands: Implications for conservation and restoration
- 2010
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048. ; 3:4, s. 357-365
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Tidskriftsartikel (refereegranskat)abstract
- Species diversity in sandy grasslands is threatened by decalcification and eutrophication. To determine the most appropriate conditions for red-listed gasteromycete fungi in such grasslands, we investigated their pH preferences in this habitat in southern Sweden. During two winters soil samples were collected from the vicinity of mycelia of these species. Chemical analysis revealed that none of the fungi occurred in sandy habitats with a pH lower than 5, although pH values between 4 and 5 are very common in sandy grasslands in the area. We found niche differentiation within the genus Tulostoma in that two out of four species occurred mainly in soils with high lime content, while one had a broad niche and one occurred mainly in soils low in lime and with a pH below 7.5. Also in the genus Geastrum, some species occurred at high lime content, while most Geastrum as well as two Disciseda species preferred soils with only low amounts of lime. We conclude that many species prefer areas with neutral to slightly acid soil. The results were compared with data for key plant species collected in a previous study of calcareous sandy grasslands and this showed that these in general had a wider pH range than the studied fungi. The results highlight the importance of varying pH levels in protected areas and that the transition zone between lime-containing topsoil and complete decalcification is a preferred environment for many red-listed fungi as well as plants.
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| 6. |
- Schnoor, Tim Krone
(författare)
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Disturbance Effects on Plant and Mycorrhizal Communities in Sandy Grasslands
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many ecosystems have historically been disturbed, either naturally or as part of a cultural management. Due to loss of species as a result of too little disturbance, disturbance must be considered as a potential tool for conservation and restoration in various ecosystems. In this thesis work, disturbance effects on a grassland system were studied. The studied grassland had traditionally been severely disturbed, both by grazing animals and wind erosion, and through agricultural practices. By experimentally disturbing the soil in the dry sandy grassland, disturbance-induced effects on plant and arbuscular mycorrhizal communities in sandy grasslands was studied. Ploughing and harrowing had no effects on soil pH and only small effects on available phosphorous was found. A positive effect on plant species richness and abundance of red-listed annuals in dry calcareous grasslands was found. The plant species richness shifted towards one comprised mainly of early successional species, but during the four years of this study, the succession went towards the pre-disturbance state rather than the restoration target defined for the area. It was found that a functional trait approach to evaluate disturbance effects was not sufficient to fully explain the reasons for the disturbed plots to diverge from the target areas. However, the functional approach showed that disturbance increased the incidence of nitrogen favoured species in the system. By using Sanger sequencing it was shown that ploughing had a negative effect on the abundance and species richness of arbuscular mycorrhiza two years after disturbance. However, in a second experiment, at a different site and using pyrosequencing, small-scale disturbances was not shown to affect either species richness or composition of arbuscular mycorrhizal fungal communities 4.5 months after disturbances. Carbon flows through arbuscular mycorrhizal fungi was negatively affected by disturbance, mainly due to a decreased abundance of arbuscular mycorrhizal fungi and potential host plants. In summary, disturbance was shown to have both positive and negative effects on the studied organisms in dry sandy grasslands. Ploughing and harrowing were not good options for restoring this specific dry calcareous grassland type although some of the wanted annual targets increased in incidence. Mycorrhizal abundance could potentially be decreased following disturbance and with it the potential soil carbon sequestration. Using disturbance for restoration purposes involves complex responses with potentially disparate responses in different organisms within the same community.
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| 7. |
- Schnoor, Tim Krone, et al.
(författare)
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Effects of soil disturbance on plant diversity of calcareous grasslands
- 2010
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 1873-2305 .- 0167-8809. ; 139:4, s. 714-719
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Tidskriftsartikel (refereegranskat)abstract
- A soil disturbance experiment was performed during two seasons in degraded, calcareous sandy grassland in southern Sweden. pH, extractable phosphorus, plant species richness and vegetation composition were analyzed. Mechanical soil disturbance had no effect on pH, and caused only a minor increase in extractable phosphorus. Positive effects compared to control plots were seen on plot scale (360 m2) in species richness and Shannon index 2 years after treatment, while on a smaller scale (1 m2), species richness increased only in rotavated plots. Plant community differences were mainly found between disturbed and control plots, and some positive effects were detected on early establishing species, but the two disturbance techniques favored different species. It is concluded that mechanical soil disturbance, and a variation in techniques and intensities, may be an important measure for preserving diversity in grasslands that have a history of mechanical soil disturbance.
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| 8. |
- Schnoor, Tim Krone, et al.
(författare)
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Mechanical soil disturbance as a determinant of arbuscular mycorrhizal fungal communities in semi-natural grassland.
- 2011
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 1432-1890 .- 0940-6360. ; 21:3, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- While the effect of disturbance on overall abundance and community composition of arbuscular mycorrhizal (AM) fungi has been researched in agricultural fields, less is known about the impact in semi-natural grasslands. We sampled two AM plant species, Festuca brevipila and Plantago lanceolata, from an ongoing grassland restoration experiment that contained replicated plowed and control plots. The AM fungal community in roots was determined using nested PCR and LSU rDNA primers. We identified 38 phylotypes within the Glomeromycota, of which 29 belonged to Glomus A, six to Glomus B, and three to Diversisporaceae. Only three phylotypes were closely related to known morphospecies. Soil disturbance significantly reduced phylotype richness and changed the AM fungal community composition. Most phylotypes, even closely related ones, showed little or no overlap in their distribution and occurred in either the control or disturbed plots. We found no evidence of host preference in this system, except for one phylotype that preferentially seemed to colonize Festuca. Our results show that disturbance imposed a stronger structuring force for AM fungal communities than did host plants in this semi-natural grassland.
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| 9. |
- Schnoor, Tim Krone, et al.
(författare)
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Soil disturbance alters plant community composition and decreases mycorrhizal carbon allocation in a sandy grassland.
- 2011
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 167, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- We have studied how disturbance by ploughing and rotavation affects the carbon (C) flow to arbuscular mycorrhizal (AM) fungi in a dry, semi-natural grassland. AM fungal biomass was estimated using the indicator neutral lipid fatty acid (NLFA) 16:1ω5, and saprotrophic fungal biomass using NLFA 18:2ω6,9. We labeled vegetation plots with (13)CO(2) and studied the C flow to the signature fatty acids as well as uptake and allocation in plants. We found that AM fungal biomass in roots and soil decreased with disturbance, while saprotrophic fungal biomass in soil was not influenced by disturbance. Rotavation decreased the (13)C enrichment in NLFA 16:1ω5 in soil, but (13)C enrichment in the AM fungal indicator NLFA 16:1ω5 in roots or soil was not influenced by any other disturbance. In roots, (13)C enrichment was consistently higher in NLFA 16:1ω5 than in crude root material. Grasses (mainly Festuca brevipila) decreased as a result of disturbance, while non-mycorrhizal annual forbs increased. This decreases the potential for mycorrhizal C sequestration and may have been the main reason for the reduced mycorrhizal C allocation found in disturbed plots. Disturbance decreased the soil ammonium content but did not change the pH, nitrate or phosphate availability. The overall effect of disturbance on C allocation was that more of the C in AM fungal mycelium was directed to the external phase. Furthermore, the functional identity of the plants seemed to play a minor role in the C cycle as no differences were seen between different groups, although annuals contained less AM fungi than the other groups.
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| 10. |
- Schnoor, Tim Krone, et al.
(författare)
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Soil disturbance as a grassland restoration measure-effects on plant species composition and plant functional traits.
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:4
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Tidskriftsartikel (refereegranskat)abstract
- Soil disturbance is recognized as an important driver of biodiversity in dry grasslands, and can therefore be implemented as a restoration measure. However, because community re-assembly following disturbance includes stochastic processes, a focus only on species richness or establishment success of particular species will not inform on how plant communities respond ecologically to disturbance. We therefore evaluated vegetation development following disturbance by quantifying species richness, species composition and functional trait composition. Degraded calcareous sandy grassland was subjected to experimental disturbance treatments (ploughing or rotavation), and the vegetation was surveyed during four subsequent years of succession. Treated plots were compared with control plots representing untreated grassland, as well as nearby plots characterized by plant communities representing the restoration target. Species richness and functional diversity both increased in response to soil disturbance, and rotavation, but not ploughing, had a persistent positive effect on the occurrence of specialist species of calcareous sandy grassland. However, no type of soil disturbance caused the plant species composition to develop towards the target vegetation. The disturbance had an immediate and large impact on the vegetation, but the vegetation developed rapidly back towards the control sites. Plant functional composition analysis indicated that the treatments created habitats different both from control sites and target sites. Community-weighted mean Ellenberg indicator values suggested that the observed plant community response was at least partially due to an increase in nitrogen and water availability following disturbance. This study shows that a mild type of disturbance, such as rotavation, may be most successful in promoting specialist species in calcareous sandy grassland, but that further treatments are needed to reduce nutrient availability. We conclude that a functional trait based analysis provides additional information of the vegetation response and the abiotic conditions created, complementing the information from the species composition.
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