| 1. |
- Asplund, Johan, et al.
(författare)
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Simulated nitrogen deposition influences gastropod grazing in lichens
- 2010
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 17:1, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- Lichens are often important photosynthetic organisms in oligotrophic environments where high-quality fodder plants are rare. A strong herbivore defence and/or low nutritional quality allows the accumulation of a high lichen biomass in such areas. However, it is not known how N deposition influences lichen palatability. This study analyzes possible changes in gastropod grazing preference after 3 months simulated N deposition on 3 foliose (Lobaria scrobiculata, Platismatia glauca, and Xanthoria aureola) and 1 pendulous lichen species (Alectoria sarmentosa). Lichens were daily irrigated in the field with rainwater containing 1.625 mM NH4NO3 from June to September, equivalent to a deposition of 50 kg N·ha-1·y-1. Irrigations applied at night, morning, or noon simulated different C-gain regimes. Afterwards in the lab, we offered 2 common lichen-feeding gastropods the choice between N-fertilized thalli and control thalli irrigated with artificial rainwater. The gastropods clearly preferred the unfertilized thalli of the 3 foliose species. For the pendulous A. sarmentosa, the gastropods preferred N-enriched thalli (irrigated at night) to controls. In conclusion, N-enrichment changes the palatability of lichens in species-specific ways.
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| 2. |
- Chiari, Stefano, et al.
(författare)
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Habitat of an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands
- 2012
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 19, s. 299-307
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Tidskriftsartikel (refereegranskat)abstract
- The habitat of Osmoderma eremita, a European endangered beetle species restricted to tree cavities, was examined in central Italy, at the southernmost limit of its distributional range. The occurrence of adults, larvae, and fragments was investigated in 170 and 151 living hollow trees by pitfall trapping and sampling of wood mould (i.e., loose material) in the hollow, respectively. Overall, O. eremita was present in 22% of the trees, which belonged to 4 different tree species (Ostrya carpinifolia, Quercus suber, Acer obtusatum, and Quercus pubescens). The frequency of presence was higher in cavities with more than 4 L of wood mould, in cavities with dry or half-moist wood mould rather than wet wood mould, and with wood mould with low soil contamination. A comparison with northern regions indicated that the warmer macro-climatic conditions in the south make the species independent of a warm microclimate. As most of the hollow trees contain only a small amount of wood mould (<4 L), the habitat quality is generally poorer than in oak pastures studied in northern Europe.
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| 3. |
- Dahlberg, Anders, et al.
(författare)
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Effects of ecological continuity on species richness and composition in forests and woodlands: A review
- 2014
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 21, s. 34-45
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Forskningsöversikt (refereegranskat)abstract
- Forests and woodlands with a long, uninterrupted presence (continuity) are often associated with high biodiversity and many habitat specialist species. But the mechanisms by which, and the scales in time and space at which, populations are dependent on continuity remain debated. We examine the spatial and temporal scales at which occurrences of plants, fungi, and invertebrates are affected by continuity and consider whether they are restricted by time for colonization (continuity per se) or by habitat formation times. We give improved definitions of landscape and local levels of continuity anti evaluate the empirical literature with respect to these. By critically examining the reported effects of continuity on the occurrence of species in forests and woodlands, we explore the mechanisms behind the patterns at local and landscape scales. We conclude that many species are dispersal-limited in the current fragmented landscapes and occur mainly in landscapes with surplus continuity, meaning that the availability of habitats was greater in the past than it is currently. Our review indicates that local continuity per se is important at least for many forest herbs and for certain species of epiphytic lichens, insects, and land snails, but to a lesser extent for fungi. Several studies show that landscape-level continuity affects the current occurrence of species, in particular for vascular plants, but also for particular lichen, bryophyte, and invertebrate species. For continuity-dependent species, a successful conservation strategy should include both extending the period of habitat duration in relict patches and promoting habitat formation in the immediate surroundings of potential source patches. Conservation strategies need to acknowledge the continuity dependence of many species. Research on how to shorten habitat formation times by forest restoration is an urgent priority.
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| 4. |
- Fransson, Petra, et al.
(författare)
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Host plant-ectomycorrhizal fungus combination drives resource allocation in willow: Evidence for complex species interaction from a simple experiment
- 2013
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 20, s. 112-121
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Tidskriftsartikel (refereegranskat)abstract
- Root-associated mycorrhizal fungi affect plant growth and resource allocation. Our major aim was to explore the plant-internal mechanisms behind the effects of mycorrhizal colonization on leaf chemistry of willow (Salix spp.). Combinations of 2 willow varieties (Loden, Tora) and 2 ectomycorrhizal fungal species (Hebeloma fastibile, Tricholoma cingulatum) were grown under controlled conditions. Host plant variety and fungal species effects on host resource allocation (biomass and leaf chemistry) varied in a complex way. Shoot biomass growth and allocation was mostly affected by host plant variety, whereas leaf and root biomass allocation were strongly affected by mycorrhizal treatment. Leaf biomass production was affected by willow variety, mycorrhizal treatment, and the interaction between them. The results indicate a strong effect of mycorrhizal colonization on host plant biomass allocation, which can mediate mycorrhizal effects on leaf chemistry. For example, leaf biomass allocation was inversely correlated with foliar concentrations of salicylic acid, suggesting a functional link between the two. However, the apparent complexity of the host plant variety-fungal species interaction makes any prediction of their possible outcome very difficult, especially in an ecological context. Still, fungal species identity seems to be more important for the responses of Salix to mycorrhizal colonization than the amount of fungal biomass.
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| 5. |
- Hambäck, Peter A., et al.
(författare)
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Plant trait-mediated interactions between early and late herbivores on common figwort (Scrophularia nodosa) and effects on plant seed set
- 2011
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 18:4, s. 375-381
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the interactive effects of early and late season herbivory on the growth and reproductive output of figwort (Scrophularia nodosa). The early season herbivore is a pentatomid bug that feeds on and kills the apical meristem, while the late season herbivores are 2 weevil species and a sawfly that all feed on leaves and flowers. The direct effect of early season meristem damage on plant reproduction was quite limited, although meristem damage did cause increased branching. This change in plant morphology may entail that early season herbivores have profound indirect effects on plant reproduction by affecting the abundance of and damage caused by late season herbivores. Comparisons of plants with and without early season meristem damage, natural and artificial, also suggest that plants with meristem damage are significantly shorter throughout most of the summer and receive less damage late in season. However, the reduced damage translated to increased flowering but not to increased fruit production, suggesting that the plants were able to compensate for late season damage. In the end, and despite damage, figwort was well able to tolerate the observed meristem and leaf damage.
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| 6. |
- Jurczyk, M., et al.
(författare)
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Utilization of prey-rich patches leads to reproductive advantages for clustered individuals of a web-building spider
- 2012
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 19:2, s. 170-176
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Tidskriftsartikel (refereegranskat)abstract
- The ideal free distribution (IFD) model predicts that consumers match the distribution of resources across habitat patches and that this association should lead to equal individual fitness among individuals in a population. Here we studied to what extent predators utilize different prey groups and if the resulting spatial patterns relate to the reproductive success of individuals in a population of a web-building spider species (Phylloneta impressa, Theridiidae). Web-building spiders, their prey remains, egg sacs, and spiderlings were collected in a wheat field, and coordinates of web sites were recorded for spatial point pattern analysis using pair and mark correlation functions. Spiders were aggregated in the study area, but only post-reproductive females were aggregated over the full range of spatial scales. Web-owners in clusters caught a higher proportion of hemipteran prey than expected by the mean, suggesting that the availability of this prey type contributed to the clustering of individuals and the higher reproductive success of females in clusters. However, 2 abundant prey groups (Syrphidae and Hymenoptera) were not more common than expected by the mean at any distance, and another prey group (Elateridae) was even less common in webs close to each other. At least 2 prey groups (Hemiptera and Elateridae) showed deviations from the assumption of the IFD model that predators in clusters should have similar prey capture success compared to predators that are not located in clusters. Both prey groups include many cereal pest species, and our results suggest that spatially explicit information about prey utilization and predator fitness may contribute to a better understanding of the role of natural enemies in biological control.
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| 7. |
- Lönnberg, Karin, 1975-, et al.
(författare)
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Seed size and recruitment patterns in a gradient from grassland to forest
- 2012
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Ingår i: Ecoscience. - : Informa UK Limited. - 1195-6860. ; 19:2, s. 140-147
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Tidskriftsartikel (refereegranskat)abstract
- Seedlings germinating from large seeds are known to endure hazards such as shading, competition, and litter coverage better than seedlings germinating from small seeds. However, few studies have assessed the relationships between seed size and recruitment comparing plant communities with different structures in order to establish the conditions under which a seed-size advantage prevails. Here, seeds from 20 species varying in seed size from 0.05 to 17.8 mg were sown in 6 different vegetation types, representing a gradient from open grassland to closed canopy coniferous forest. We hypothesized that the effect of seed size on recruitment is generally positive, but that there is a stronger positive effect of seed size in closed than in open communities. Our results provided only limited support for this hypothesis. Firstly, the results varied between years, suggesting that any seed size advantage may depend on factors varying on an annual basis. Secondly, although there were trends of significantly positive relationships between seed size and seedling emergence, seedling survival, and recruitment success, particularly in relatively more closed vegetation types, the strongest positive effects of seed size were found in intermediate (semi-open) habitats along the gradient. We conclude that the filtering of species into the investigated communities is only weakly related to seed size, and that several factors other than canopy probably influence the link between seed size and recruitment.
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| 8. |
- Ranius, Thomas, et al.
(författare)
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How frequent is metapopulation structure among butterflies in grasslands? Occurrence patterns in a forest-dominated landscape in southern Sweden
- 2011
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 18:2, s. 138-144
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Tidskriftsartikel (refereegranskat)abstract
- We determined the proportion of butterfly species that occur as metapopulations with grasslands as the only habitat. We counted all butterflies in 19 semi-natural grassland patches in a forest-dominated landscape in southern Sweden over a 5-y period. Seven of the 44 butterfly species observed exhibited a metapopulation structure. The other species either use grassland mainly for adult feeding but not for breeding (8 species), breed both in grassland and in surrounding habitat types (19 species), or are grassland specialists but their colonization-extinction dynamics are probably not significant, since they were present in nearly all (> 80%) patches (10 species). Occupancy was generally higher in larger patches, and tended to increase with patch connectivity. Among grassland specialists and habitat generalists, the connectivity measure tended to explain more of the variation in occupancy if the shortest dispersal paths avoiding routes over water were considered rather than a measure based on the Euclidian distance between patches. This indicates that lakes, even when they are just a few hundred metres wide, can act as barriers to dispersal for butterflies. We conclude that for many butterflies that occur in semi-natural grasslands in forest-dominated landscapes, intervening habitats are important as breeding sites or as dispersal barriers.
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