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| 2. |
- 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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| 3. |
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| 4. |
- Brunet, J, et al.
(författare)
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Interannual variability in abundance of field layer species in a south Swedish deciduous wood
- 2000
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Ingår i: Flora: Morphology, Distribution, Functional Ecology of Plants. - 0367-2530. ; 195:2, s. 97-103
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Tidskriftsartikel (refereegranskat)abstract
- Variability in cover of five field layer species was recorded during ten consecutive years in thirty permanent plots within a south Swedish Carpinus betulus forest. The studied species were Oxalis acetosella, Lamium galeobdolon, Stellaria holostea, Hedera helix and Holcus mollis. We observed great interannual variability in cover percentage of all studied species with 76% out of all year-to-year differences being statistically significant (P < 0.05). However, a very high persistence of all species was recorded with very few colonizations or extinctions at the sample plot scale. Regression analyses showed that cover changes of Oxalis, Lamium, Stellaria and Holcus were related to amounts of rainfall. Longer periods of dry weather during early summer of the current year or during late summer of the previous year reduced the abundance of these species. Cover of pairs of species was mostly positively correlated, indicating that interspecific competition was less important in accounting for abundance changes during the study period. Long-term trends were observed in Hedera helix (decrease) and Holcus mollis (increase) and may be explained by current soil acidification in the study area. Our results show that environmental monitoring of permanent plots for the study of long-term vegetation changes must account for interannual variability in species cover.
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| 5. |
- Caron, M. M., et al.
(författare)
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Impacts of warming and changes in precipitation frequency on the regeneration of two Acer species
- 2015
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Ingår i: Flora. - : Elsevier BV. - 0367-2530 .- 1618-0585. ; 214, s. 24-33
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Tidskriftsartikel (refereegranskat)abstract
- Climate projections indicate that temperatures will increase by up to 4.5 degrees C in Europe by the end of this century, and that more extreme rainfall events and longer intervening dry periods will take place. Climate change will likely affect all phases of the life cycle of plants, but plant reproduction has been suggested to be especially sensitive. Here, using a combination of approaches (soil heaters and different provenances along a latitudinal gradient), we analyzed the regeneration from seeds of Acer platanoides and A. pseudoplatanus, two tree species considered, from a management point of view, of secondary relevance. We studied germination, seedling survival and growth in a full-factorial experiment including warming and changes in watering frequency. Both species responded to warming, watering frequency and seed provenance, with stronger (negative) effects of warming and provenance than of watering frequency. In general, the central provenances performed better than the northernmost and southern-most provenances. We also detected interactive effects between warming, watering frequency and/or seed provenance. Based on these results, both species are expected to show dissimilar responses to the changes in the studied climatic factors, but also the impacts of climate change on the different phases of plant regeneration may differ in direction and magnitude. In general increases in the precipitation, frequency will stimulate germination while warming will reduce survival and growth. Moreover, the frequent divergent responses of seedlings along the latitudinal gradient suggest that climate change will likely have heterogeneous impacts across Europe, with stronger impacts in the northern and southern parts of the species' distribution ranges.
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| 6. |
- Dayamba, Sidzabda Djibril, et al.
(författare)
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Effects of aqueous smoke solutions and heat on seed germination of herbaceous species of the Sudanian savanna-woodland in Burkina Faso
- 2010
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Ingår i: Flora. - : Elsevier BV. - 0367-2530 .- 1618-0585. ; 205, s. 319-325
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Tidskriftsartikel (refereegranskat)abstract
- Smoke generated by burning of plant materials has widely been recognized as a germination cue for some species from both fire prone and fire-free ecosystems. It is an important factor for the understanding of vegetation dynamics and could have potential use for ecological management and rehabilitation of disturbed areas. Individual species, however, seem to have a specific requirement for the type and dosage of smoke treatments. In the present study, six different concentrations of smoke solution were tested on 13 herbaceous species by soaking the seeds for 24 h. The germination of a forb species, Borreria scabra, was significantly stimulated (p < 0.05) by the smoke treatment while that of the annual grass species, Euclasta condylotricha, was significantly inhibited (p < 0.05) by 100% smoke solution treatment. Contrary to our expectation that another fire-related cue, heat shock, would break the physical dormancy of the species tested, it was not promotive. For non-dormant seeds of B. scabra and Borreria radiata, high temperatures were lethal while low temperature induced physiological dormancy that was overcome in the former species within 30 days of the germination trial. For some species, responses to smoke did not corroborate with the field-observed response to fire, making ecological interpretation challenging. For responsive species, the smoke treatment could be a simple approach for promoting their re-establishment in areas where it is needed. More investigations are needed to assess the spread of response to smoke. (C) 2010 Elsevier GmbH. All rights reserved.
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| 7. |
- Eckstein, Rolf Lutz, et al.
(författare)
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Evidence for consistent trait-habitat relations in two closely related violets of contiguous habitat types from a fertilisation experiment
- 2004
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Ingår i: Flora. - 0367-2530 .- 1618-0585. ; 199:3, s. 234-246
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Tidskriftsartikel (refereegranskat)abstract
- Most studies on the adaptive significance of plant traits compared species that differed in inherent growth rate or species of habitats at the extremes of environmental gradients. In the present paper, we compared the response of Viola elatior and V. pumila, two closely related and morphologically similar violets to the experimental variation of nitrogen availability. The species occur in adjacent habitat types, viz. alluvial forest fringes (V. elatior) and floodplain meadows (V. pumila), that differ in resource availability and disturbance across a relatively small gradient. We tested the hypotheses that, according to their typical habitat, V. elatior should show more traits of a stress tolerant competitive plant, while V. pumila should exhibit more ruderal traits. We carried out a two-year common garden experiment with two levels of fertiliser addition (N5, 5 g N m(-2) yr(-1); N20, 20 g N m(-2) yr(-1)), and analysed a number of traits related to relative growth rate (RGR), allocation, and nutrient use. We further did an experiment with seeds from the experimental plants to study variation in germination rate. We found considerable ontogenetic drift in the species during two years of growth. In the first year, both species showed similar mass and growth rate but these were achieved through different trait combinations. In the second year, V. elatior had a higher RGR, produced more biomass per unit nutrient and developed more leaf area per unit plant mass than V. pumila, while the latter produced thinner leaves. V. pumila had a higher capacity for nutrient acquisition, but a large proportion of the captured nutrients were used for reproduction. Germination rate was higher in V. pumila than in V. elatior, independent of the nutrient status of the mother plant, while seeds of V. elatior from N20 plants had a significantly higher germination rate (67%) than seeds from N5 plants (35%). Our data suggested that many of the analysed trait differences seem to be consistent with the requirements of the different habitat types.
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| 8. |
- Henriksson, Natalie D., et al.
(författare)
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Topsoil removal enhances plant target species occurrence in sandy calcareous grassland
- 2019
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Ingår i: Flora: Morphology, Distribution, Functional Ecology of Plants. - : Elsevier BV. - 0367-2530. ; 256, s. 7-15
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Tidskriftsartikel (refereegranskat)abstract
- Species-rich sandy calcareous grasslands are threatened by land use change, eutrophication and acidification. Disturbance is vital for the persistence of characteristic sandy calcareous grassland species because it provides habitats with low competition, and can lead to increased pH and decreased nutrient availability, which favour many threatened species. Today many sandy calcareous grasslands lack a proper disturbance regime. The outcome of topsoil removal, applied as restoration measure, was investigated in a multi-site study. Successful restoration was associated with colonisation of plants representing conservation target species, as well as increased pH and reduced amounts of nutrients and organic matter. The impact of topsoil removal on plant species composition and soil properties was examined, with adjacent degraded plots serving as controls. Non-degraded target vegetation was included as reference areas. Restored plots had a significantly higher mean proportion of target species compared to control plots. However, control plots had higher species richness. Topsoil removal increased the pH value and decreased contents of ammonium and organic matter in the newly established topsoil layer, while no effect was seen on nitrate, phosphate and lime. Restored plots had a high cover of bare sand, but in contrast to target plots, a rather low proportion of forbs in relation to graminoids. Control plots had a higher vegetation cover, mainly represented by graminoids, forbs and the dwarf shrub species Calluna vulgaris (L.) Hull. Our study suggests that topsoil removal is an effective restoration measure due to its positive influence on soil characteristics and target species. However, the degraded sandy grasslands that were chosen as controls in this study should also be recognised as important habitats with conservation values due to the high species richness, suggesting that a mosaic pattern of the different successional stages is desirable.
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| 9. |
- Hensgen, Frank, et al.
(författare)
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Distribution of gastropods in floodplain compartments and feeding preferences for river corridor plant species : Is there an effect of gastropod herbivory on the distribution of river corridor plants?
- 2011
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Ingår i: Flora. - : Elsevier. - 0367-2530 .- 1618-0585. ; 206:6, s. 534-543
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Tidskriftsartikel (refereegranskat)abstract
- Herbivory through gastropods has among others been proposed as a potential factor responsible for the river corridor distribution of plant species, which is a well known but poorly understood ecological pattern. Since floodplains are characterised by seasonally changing abiotic conditions, viz, floods during winter and spring and severe summer drought that are unsuitable for gastropods they may present safe habitats for highly palatable plant species. In the present study we compared species composition of gastropods and vegetation of twelve grassland sites situated within three floodplain compartments along the Upper Rhine. Additionally, we studied the palatability of 7 days and 25 days old seedlings of five typical floodplain plant species and five mesic grassland species to the slug Deroceras reticulatum in laboratory experiments. Our results showed that both vegetation and gastropod community composition but not gastropod diversity and abundance differed between floodplain compartments. Owing to omnivory of most gastropods the similarity structure of sites based on plants and gastropods was not significantly correlated. In general, slug herbivory significantly reduced survival and biomass of 7 days old seedlings, but responses were species-specific. In contrast, with the exception of Arabis nemorensis, Viola pumila and Taraxacum sect. Ruderalia biomass of 25 days old seedlings was not significantly affected by slug herbivory. Although the response of floodplain plant species as a group to slug herbivory did not differ from common grassland species, our results suggest that gastropods may potentially influence the distribution pattern of the highly palatable river corridor species Arabis nemorensis and Viola pumila. However, further research is needed to estimate the damage to river corridor plants through gastropod herbivory and its effect on competitive relationships under natural conditions.
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| 10. |
- Karlsson, Laila, et al.
(författare)
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Variation within species and inter-species comparison of seed dormancy and germination of four annual Lamium species
- 2008
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Ingår i: Flora. - : Institutionen för fysik, kemi och biologi. - 0367-2530 .- 1618-0585. ; 203:5, s. 409-420
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Tidskriftsartikel (refereegranskat)abstract
- In an ecological context, knowledge of intra-species variation in dormancy and germination is necessary both for practical and theoretical reasons. We used four or five seed batches (replicates) of four closely related annuals co-occurring in arable fields in Sweden: Lamium amplexicaule, L. confertum, L. hybridum and L. purpureum. Seeds used for experiments stemmed from plants cultivated on two sites, each site harbouring one population of each species, thereby ensuring similar environmental history of seeds. Seeds were tested for germination when fresh and after three different pre-treatments (cold or warm stratification, or dry storage) for up to 24 weeks. Seeds were also sown outdoors. Despite substantial intra-species variation, there were clear differences between species. The general seed dormancy pattern, i.e. which environmental circumstances that affect dormancy, was similar for all species; dormancy reduction occurred during warm stratification or dry storage. Even though the response to warm stratification indicate a winter annual pattern, successful plants in Sweden were mostly spring emerged. Germination in autumn occurred, but plants survived winters poorly. Consequently, as cold stratification did not reduce dormancy, strong dormancy in combination with dormancy reduction during dry periods might explain spring germination. It is hypothesized that local adaptations occur through changes mainly in dormancy strength, i.e. how much effort that is needed to reduce dormancy; strong dormancy restrict the part of each seed batch that germinate during autumn, and thus risk winter mortality, in Sweden.
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