| 1. |
- Backéus, Ingvar, 1945-, et al.
(författare)
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Var Sellingaffären kulmen på en sekellång botanisk konflikt?
- 2018
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 112:6, s. 380-393
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Tidskriftsartikel (refereegranskat)abstract
- The 1950s saw a series of miscarriages of justice against public persons in Sweden. In one of these, the Royal Swedish Academy of Sciences tried to force Olof Selling from his professorship in paleobotany at the Swedish Museum of Natural History, on the basis of mental illness, but this failed after a long and public calamity. In his book Naturen inför rätta [Nature facing trial], Keith Wijkander (2017) claims that Selling was the victimof a century-long conflict between botanists in Uppsala and Stockholm,and places Selling in the Uppsala camp. We try to give a more balanced picture of the relationships between plant ecology in Uppsala and Stockholm during the early 20th century. R. Sernander, L.-G. Romell and G. E. Du Rietz are among the main actors. The fierce debates between the two camps make this an interesting period in Swedish botany.
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| 2. |
- Eshghi Sahraei, Shadi, et al.
(författare)
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Effects of operational taxonomic unit inference methods on soil microeukaryote community analysis using long‐read metabarcoding
- 2022
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Long amplicon metabarcoding has opened the door for phylogenetic analysis of the largely unknown communities of microeukaryotes in soil. Here, we amplified and sequenced the ITS and LSU regions of the rDNA operon (around 1500 bp) from grassland soils using PacBio SMRT sequencing. We tested how three different methods for generation of operational taxonomic units (OTUs) effected estimated richness and identified taxa, and how well large-scale ecological patterns associated with shifting environmental conditions were recovered in data from the three methods. The field site at Kungsängen Nature Reserve has drawn frequent visitors since Linnaeus's time, and its species rich vegetation includes the largest population of Fritillaria meleagris in Sweden. To test the effect of different OTU generation methods, we sampled soils across an abrupt moisture transition that divides the meadow community into a Carex acuta dominated plant community with low species richness in the wetter part, which is visually distinct from the mesic-dry part that has a species rich grass-dominated plant community including a high frequency of F. meleagris. We used the moisture and plant community transition as a framework to investigate how detected belowground microeukaryotic community composition was influenced by OTU generation methods. Soil communities in both moisture regimes were dominated by protists, a large fraction of which were taxonomically assigned to Ciliophora (Alveolata) while 30%–40% of all reads were assigned to kingdom Fungi. Ecological patterns were consistently recovered irrespective of OTU generation method used. However, different methods strongly affect richness estimates and the taxonomic and phylogenetic resolution of the characterized community with implications for how well members of the microeukaryotic communities can be recognized in the data.
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| 3. |
- Hytteborn, Håkan, et al.
(författare)
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Century-long tree population dynamics in a deciduous forest stand in central Sweden
- 2017
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Ingår i: Journal of Vegetation Science. - : Wiley. - 1100-9233 .- 1654-1103. ; 28:5, s. 1057-1069
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Tidskriftsartikel (refereegranskat)abstract
- Question: We quantify tree dynamics over a century of free development in a small broadleaved forest dominated by Fraxinus excelsior and Ulmus glabra. What are the internal and external factors driving the changes, and how predictable are they? What were the time scale and effects of the spread of Dutch elm disease (DED)? Location: Vårdsätra, eastern central Sweden.Methods: The survival, growth and recruitment of all trees (≥ 12 cm in girth) were monitored in 1912, 1967, 1988 and 2013 (more often for a part of the forest). Woody species in the field and shrub layers were surveyed in permanent plots in 1976 and 2012. We used transition matrix models to project changes in population sizes and species composition within the century and for 2050.Results: The results indicate that the forest was in a successional development during the first period. The species composition had stabilised by 1967, except for an expansion of Acer platanoides and the drastic effect of DED that struck the forest around 2000. It took only a decade to kill virtually all large elms in the forest, leading to strong decrease in stem density and basal area. The evidence for effects of DED is still weak, but there has been an increase in saplings, notably of Fraxinus, Prunus padus, Ulmus, and of shoots of Corylus avellana. Several species that are abundant in the vicinity and as seeds fail to establish (Picea abies, Betula spp., Quercus robur, Populus tremula). Projections for 2050 based on the third period (1988-2013) are probably unrealistic since also Fraxinus may disappear because of the recent arrival of the ash dieback.Conclusions: Slow dynamics in forests that could follow from climate change will locally probably be overruled by unforeseen catastrophes, such as invasions by forest pathogens. These initiate changes with long lag phases difficult to quantify. Still, a dense deciduous forest can resist invasion of colonist species and of regionally dominant conifers; the reason being unfavourable conditions for establishment rather than dispersal limitation
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| 4. |
- Hytteborn, Håkan, et al.
(författare)
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Spatial heterogeneity ensures long-term stability in vegetation and Fritillaria meleagris flowering in Uppsala Kungsäng, a semi-natural meadow
- 2023
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 18:3
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Tidskriftsartikel (refereegranskat)abstract
- Semi-natural grasslands are becoming increasingly rare, and their vegetation may be affected by environmental changes and altered management. At Kungsängen Nature Reserve, a wet to mesic semi-natural meadow near Uppsala, Sweden, we analysed long-term changes in the vegetation using data from 1940, 1982, 1995 and 2016. We also analysed the spatial and temporal dynamics in the Fritillaria meleagris population based on countings of flowering individuals in 1938, 1981–1988 and 2016–2021. Between 1940 and 1982 the wet part of the meadow became wetter, which led to an increased cover of Carex acuta and pushed the main area of flowering of F. meleagris up towards the mesic part. Annual variation in the flowering propensity of F. meleagris (in May) was affected by temperature and precipitation in the phenological phases of growth and bud initiation (June in the previous year), shoot development (September in the previous year) and initiation of flowering (March–April). However, the response to weather was in opposite directions in the wet and mesic parts of the meadow, and the flowering population showed large year-to-year variation but no long-term trend. Variation in management (poorly documented) led to changes in different parts of the meadow, but the overall composition of the vegetation, species richness and diversity changed little after 1982. Species richness and species composition of the meadow vegetation, and the long-term stability of the F. meleagris population are maintained by the variation in wetness, highlighting the importance of spatial heterogeneity as an insurance against biodiversity loss in semi-natural grasslands and nature reserves generally.
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| 5. |
- 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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| 6. |
- Bengtsson, Fia, 1986-, et al.
(författare)
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Environmental drivers of Sphagnum growth in peatlands across the Holarctic region
- 2021
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Ingår i: Journal of Ecology. - : John Wiley & Sons. - 0022-0477 .- 1365-2745. ; 109:1, s. 417-431
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Tidskriftsartikel (refereegranskat)abstract
- The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genusSphagnum-the main peat-former and ecosystem engineer in northern peatlands-remains unclear. We measured length growth and net primary production (NPP) of two abundantSphagnumspecies across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers onSphagnumgrowth. Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denserSphagnum fuscumgrowing on hummocks had weaker responses to climatic variation than the larger and looserSphagnum magellanicumgrowing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth forS. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influencedSphagnumgrowth indirectly by affecting moss shoot density. Synthesis. Our results imply that in a warmer climate,S. magellanicumwill increase length growth as long as precipitation is not reduced, whileS. fuscumis more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species-specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.
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| 7. |
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| 8. |
- Bengtsson, Fia, 1986-
(författare)
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Functional Traits in Sphagnum
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Peat mosses (Sphagnum) are ecosystem engineers that largely govern carbon sequestration in northern hemisphere peatlands. I investigated functional traits in Sphagnum species and addressed the questions: (I) Are growth, photosynthesis and decomposition and the trade-offs between these traits related to habitat or phylogeny?, (II) Which are the determinants of decomposition and are there trade-offs between metabolites that affect decomposition?, (III) How do macro-climate and local environment determine growth in Sphagnum across the Holarctic?, (IV) How does N2 fixation vary among different species and habitats?, (V) How do species from different microtopographic niches avoid or tolerate desiccation, and are leaf and structural traits adaptations to growth high above the water table?Photosynthetic rate and decomposition in laboratory conditions (innate growth and decay resistance) were related to growth and decomposition in their natural habitats. We found support for a trade-off between growth and decay resistance, but innate qualities translated differently to field responses in different species. There were no trade-offs between production of different decay-affecting metabolites. Their production is phylogenetically controlled, but their effects on decay are modified by nutrient availability in the habitat. Modelling growth of two species across the Holarctic realm showed that precipitation, temperature and vascular plant cover are the best predictors of performance, but responses were stronger for the wetter growing species. N2 fixation rates were positively related to moss decomposability, field decomposition and tissue phosphorus concentration. Hence, higher decomposition can lead to more nutrients available to N2-fixing microorganisms, while higher concentrations of decomposition-hampering metabolites may impede N2 fixation. A mesocosm experiment, testing effects of water level drawdown on water content and chlorophyll fluorescence, showed that either slow water loss or high maximum water holding capacity can lead to desiccation avoidance. Furthermore, leaf anatomical traits rather than structural traits affected the water economy.This thesis has advanced the emerging field of trait ecology in Sphagnum by comparing many species and revealing novel mechanisms and an ever more complex picture of Sphagnum ecology. In addition, the species-specific trait measurements of this work offers opportunities for improvements of peatland ecosystem models.
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| 9. |
- Bengtsson, Fia, et al.
(författare)
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Mechanisms behind species-specific water economy responses to water level drawdown in peat mosses
- 2020
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 126:2, s. 219-230
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Tidskriftsartikel (refereegranskat)abstract
- Background and AimsThe ecosystem engineers Sphagnum (peat mosses) are responsible for sequestering a large proportion of carbon in northern peatlands. Species may respond differently to hydrological changes, and water level changes may lead to vegetation shifts in peatlands, causing them to revert from sinks to sources of carbon. We aimed to compare species-specific responses to water level drawdown within Sphagnum, and investigate which traits affect water economy in this genus.MethodsIn a mesocosm experiment, we investigated how water level drawdown affected water content (WC) in the photosynthetically active apex of the moss and maximum quantum yield of photosystem II (i.e. Fv/Fm) of 13 Sphagnum species. Structural traits were measured, and eight anatomical traits were quantified from scanning electron microscopy micrographs.Key ResultsMixed-effects models indicated that at high water level, large leaves were the most influential predictor of high WC, and at low water level WC was higher in species growing drier in the field, with larger hyaline cell pore sizes and total pore areas associated with higher WC. Higher stem and peat bulk density increased WC, while capitulum mass per area and numerical shoot density did not. We observed a clear positive relationship between Fv/Fm and WC in wet-growing species.ConclusionsWhile we found that most hummock species had a relatively high water loss resistance, we propose that some species are able to maintain a high WC at drawdown by storing large amounts of water at a high water level. Our result showing that leaf traits are important warrants further research using advanced morphometric methods. As climate change may lead to more frequent droughts and thereby water level drawdowns in peatlands, a mechanistic understanding of species-specific traits and responses is crucial for predicting future changes in these systems.
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| 10. |
- Campbell, Charles, 1982-
(författare)
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Sphagnum limits : Physiology, morphology and climate
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sphagnum is the most important plant genus in terms of terrestrial carbon cycling. It and the habitats it creates store an equivalent of ~68% of the CO2 in the atmosphere. The genus has little dispersal limitation and the mire habitats are functionally similar at global scales. Sphagnum species are limited by water deficit at local and biogeographic scales, but this alone is not sufficient to explain local and global scale species patterns. As Sphagnum shoots are long-lived they may be limited by stochastic periods of cold temperature. Within Europe, species are associated with climate gradients along north-south (cold-warm) and oceanic-continental (wet-dry) clines. Within mires, species are sorted along a moisture (hummock-hollow) gradient.In this thesis I examined species responses to and recovery from freezing (I). I compared species with different water level niches in traits related to water management of individual shoots and colonies (II). Using distribution modelling of GBIF data, I estimated how different aspects of climate contributed to Sphagnum species distributions in Europe (III). Combining the approaches in papers II and III, I modelled the climatic distributions of the parapatric species S. cuspidatum and S. lindbergii and assessed how traits of water economy varied across the distribution boundary (IV).Species responses to winter stress were largely allied to both their hydrological niche and geographic range. Generally, hollow species managed better than hummock species, but species from intermediate positions were less consistent in their response. Species associated with boreal regions were generally less affected than those from temperate regions. Hardening against low temperature was triggered by shorter days and cold nights. Cold temperatures during late autumn may be more important for Sphagnum limits than the minimum temperature during winter.Water-related traits split the species into two groups; hollows species with large capitula and hummock species with small capitula. However, inter- and intra-specific trait variation and trait trends along the hydrological gradient were not necessarily the same at the shoot and canopy scale. Some trait correlations were common to all species. Canopy traits, which were emergent traits of colonies of shoots, had the strongest trait associations with the species position along the hummock-hollow gradient.At the continental scale the distribution of most Sphagnum species could be successfully modelled by a combination of annual degree days and water balance and the degree of seasonality in these two variables. Individual species distributions were shaped more by the seasonality in degree days than in water balance.Across the distributional border of S. cuspidatum and S. lindbergii divergence in the measured traits was mostly seen in the capitula indicating that limits to Sphagnum species are strongly linked to the functioning of the capitulum. Capitulum mass of both species was lower in sympatry than in allopatry, even though the measured values were similar. Canopy traits most strongly separated the species though did not change across the species boundaries.In summary, Sphagnum species in general are limited by the availability of water. Low temperature, particularly during late autumn are probably decisive for the biogeographic limits and for the distribution of species along the hydrological gradient.
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